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C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | (1) Factors for fruit mass were found on six chromosomes (1, 4, 6, 7, 9 and 11). In each case, CL alleles decrease fruit mass (by 3.5 to 6.0 g), adding to a total reduction of 28.1 g inferred for back-cross progeny carrying a CL allele at all six loci. This accounts for about half of the approximately 60 g difference b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The numbers of QTLs reported for each trait must be considered a minimum estimate. Because an extremely stringent threshold was used to avoid any false positives, some sub-threshold effects probably represent real QTLs. For example, the regions near TG19 on chromosome 1, CD41 on chromosome 5 and TG68 on chromosome 12 m... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The region near sp on chromosome 6 has the largest effects on soluble solids and pH, as well as a substantial effect on fruit mass. The sp gene affects plant-growth habit: the dominant CL allele causes continuous apical growth (indeterminate habit), whereas the recessive E allele causes termination in an inflorescence ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | effects in the last of these three regions only (which, interestingly, failed to show effects on soluble solids in a single-environment test by Tanksley and Hewitt13). Moreover, we detected QTLs affecting soluble-solids concentration in regions that did not seem to be retained. Unfortunately, the results of the two exp... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The general approach of QTL mapping is broadly applicable to a wide range of biological endeavours. In agriculture, it might be desirable to transfer to domestic strains many quantitative traits harboured in wild species, including resistance to diseases and pests, tolerance to drought, heat, cold and other adverse con... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | We thank Janice Chen, Mark Daly, Gerald Dickinson and Mitzi Aguirre for technical assistance. We thank our colleagues and the referees for comments on the manuscript. This work was supported in part by grants from the NSF (to E.S.L. and to S.D.T.), from the System Development Foundation (to E.S.L.), and from the US Dep... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Simmonds, N. W. Principles of Crop Improvement, 82-85 (Longman, New York, 1981).
Lande, R. Heredity 50, 47-65 (1983).
Shrimpton, A. E. & Robertson, A. Genetics 11, 445-459 (1988).
Yeager, A. F. J. Hered. 18, 263-265 (1927).
Emery, G. C. & Munger, H. M. J. Am. Soc. Hort. Sci. 95, 410-412 (1966).
Zamir, D. & Tadmor, Y. B... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 限制性酶切片段长度多态性(RFLPs)[10]的应用使得这一研究成为可能,至少在理论上此方法是可行的。在此,我们首次在番茄的种间回交实验中用完整的RFLP连锁图谱将数量性状分解为孟德尔遗传因子来研究。采用这种新的分析方法,我们鉴定出了六个控制果实质量的QTL、四个控制可溶性固形物含量的QTL以及五个控制果实pH的QTL。此方法也可广泛地应用于其他高等动植物的生理学特征、形态学特征和行为学特征数量性状的遗传学研究中。 英文
回交品种的亲本是驯养品种番茄Lycopersicon esculentum cv.UC82B(标注为E)和野生的南美绿果番茄L. chmielewskii[11] accession LA1028(标注为CL)。... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
图2.根据遗传标记的基因型和它们之间的相对距离,评估轮回亲本E基因型在237株回交子代中所占百分比的分布情况。对于检测遗传标记基因型的方法如前所述[13]。在计算轮回亲本基因组所占比例时采用了近期新研发的计算机程序—HyperGene TM (扬、佩特森和坦克斯利未发表结果)。尽管对整个回交子代来讲所计算百分比的平均值与孟德尔遗传规律所期望的75%很接近,但是对个体的植株来说此百分比则介于59%至90%以上。轮回亲本基因组在子代中所占百分比的分布情况与数学期望一致[35,36]。携带有超过90%亲本E基因组的个体似乎只携带了五个来自CL的片段(在长度上介于9到47染色体图距单位),这些个体通过两代(每代不超过100株植株)的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 此方法在数量性状位点图谱绘制上的发展在参考文献16中有更充分的展示。 英文
我们再回到最初的问题上,如何定位果实质量、可溶性固形物含量和pH值这三个连续变异背后的孟德尔遗传因子呢?最大似然法和对数优势比通常被用于人的遗传连锁分析[17],最近这些方法也被用于数量性状位点(QTL)的区间作图[16]。在基因组的每一个位置计算出QTL影响性状的“最大可能”表型效应(此效应将所观测到数据的似然最大化)和优势比(数据来自与此效应相关的QTL的概率除以与此效应无关的QTL概率的比值)。对数优势比定义为以10为底优势比的对数值,它代表了在某一位置存在与表型效应相关的QTL的证据的强度,假如对数优势比超过了预设的阈值,则认为存在QTL。作为定位... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 尽管现有的数据还不足以区分单个基因的多效性和紧密连锁的多个基因座各自独立的效应,但是同一位置的QTL时常影响着不同的遗传性状,说明可能至少某些效应是基因多效性造成的。 英文
6号染色体上接近sp基因的区域对可溶性固形物和pH值能够造成最显著的影响,对果实质量也能产生巨大的影响。sp基因能够影响植物的生长习性,其显性CL等位基因能够导致连续性的顶端生长(无限生长习性),而隐性E等位基因会终止花序的顶端生长(有限生长或自修剪习性)[21]。尽管之前的研究认为无限生长能够提高L. esculentum品种中果实的质量和可溶性固形物的含量,但是我们发现它与E×CL杂交品种和其他一些种间杂交品种(E×L. cheesmanii杂交品种;佩特森... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 作为遗传学和分子生物学的基本工具,等基因系可用于QTL的研究,包括基因互补作用、显性和上位效应、等基因系之间生理生化特性差异的鉴定、利用基因突变对其他等位基因的分离(至少是在良好的体系中的突变)以及最终对这些决定数量性状的遗传因子进行物理定位和分子克隆。 英文
在此,我们要感谢贾尼丝·陈、马克·戴利、杰拉尔德·迪金森和米蒂兹·阿吉雷在技术上的帮助。还要感谢我们的同事和审稿人对稿件提出的宝贵意见。本工作得到了美国国家科学基金会、系统发育基金和农业部的部分资助。 英文
(周晓明 翻译;方向东 审稿)
Observation of Cold Nuclear Fusion in Condensed Matter
S. E. Jones e... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | fusion rate is exceedingly slow, about 10–74 per D2 molecule per second1. 中文
By replacing the electron in a hydrogen molecular ion with a more massive charged particle, the fusion rate is greatly increased. In muon-catalysed fusion, the internuclear separation is reduced by a factor of ~200 (the ratio of the muon to el... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | To estimate a possible rate of fusion in the Earth, we assume a simple, steady-state model in which the known flux of 3He out of the mantle, 2×1019 3He atoms per second7, arises from p–d fusion occurring uniformly in the mantle water reservoir, taken as ~1.4×1024 g (R. Poreda, personal communication). Note that if the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Further evidence for cold nuclear fusion in condensed matter comes from studies of 3He and 4He in metals. There have been several reports of high 3He concentrations in metal crucibles and foils (H. Craig, R. Poreda, A. Nier, personal communications), consistent with in situ formation by cold fusion. In particular, Mamy... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | information. As their energy decreases, the neutrons are scavenged by 6Li nuclei, and the reaction n + 6Li→t + 4He results in scintillations in the glass. Pulse shapes and amplitudes from the two scintillators differ; the two distinct signals are registered by two photomultiplier tubes, whose signals are summed. A coin... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | neutrons are anticipated. By comparing energy spectra from γ-ray and neutron sources we have determined that approximately one-fourth of the observed background events arise from accidental coincidences of γ-rays and three-fourths from ambient neutrons. The γ-ray background comes mainly from radioactive radium and pota... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | During the search for suitable catalytic materials, the following (unoptimized) prescription for the electrolytic cells evolved. It began with salts typical of volcanic hot springs and included electrode-metal ions. The electrolyte is typically a mixture of ~160 g D2O plus various metal salts in ~0.1 g amounts each: Fe... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Figure 2 shows the energy spectrum obtained under the conditions described above, juxtaposed with the (scaled) background spectrum. We acquired about twice as much background data as foreground data. Assuming conservatively that all deviations from background are statistical fluctuations, we scale the background counts... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | It is instructive to examine the fourteen individual runs which enter into the combined data discussed above. These runs were performed over the period 31 December 1988 to 6 March 1989. Figure 4 displays, for each run, the ratio of foreground count rate in the 2.5-MeV energy region to the background rate obtained for e... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | test run because materials plate out of solution; the solution pH also changes significantly during a run. These 14 runs represent two choices of electrode material plus various operating currents. These variations may account for the fluctuations in the signal level that are evident in Fig. 4. As these runs represent ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 1, is based on the assumption that nearly all tetrahedral sites in the titanium lattice are occupied, forming the γ-TiD2 hydride. Then the estimated cold nuclear fusion rate for the neutron-production branch, by equation (4), is λf ≈ 10–23 fusions per deuteron pair per second. If most fusions take place near the surfac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The correlation of ideas regarding cold piezonuclear fusion1 with observations of excess 3He in metals and in geothermal areas of the Earth led to our experimental studies of fusion in electrochemical cells, which began in May 1986. Our electrolyte compositions evolved from geochemical considerations, and changed as re... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Craig, H., Lupton, J. E., Welhan, J. A. & Poreda, R. Geophys. Res. Lett. 5, 897-900 (1978).
Lupton, J. E. & Craig, H. Science 214, 13-18 (1981).
Mamyrin, B. A. & Tolstikhin, L. N. Helium Isotopes in Nature (Elsevier, Amsterdam, 1984).
Craig, H. & Lupton, J. E. in The Sea Vol. 7 (ed. Emiliani, C.) Ch. 11 (Wiley, New Yor... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 在μ子催化聚变中,核间距会缩小约200倍(即μ子与电子质量之比),相应地核聚变率也会提升约80个数量级。μ子催化聚变已经被证实为能够在氢同位素低温混合物中迅速引起聚变反应的一个有效途径[2,3]。 英文
一个假定的比电子大几倍的准粒子会将冷核聚变率增加到易于测量到的水平,即每秒钟每个氘核对中约10–20次聚变[1]。本文报告的结果表明,在特定条件下将氢同位素原子核注入到金属中,可以实现原子核间波函数相应的变化。我们已经发现了一种在既不要求高温也不使用放射性μ子的情况下实现核聚变的方法。 英文
间接证据
对地球上自然产生的3He的观测,为我们在实验室条件下研究凝聚态物质中的核聚变指明了新的方向。3He在下列聚变反应中产生:
p + d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 观测到的能谱比较宽,这意味着2.45 MeV中子应该出现在多道分析器的第45到第150道之间。通过对锎–252广谱源裂变中子计数率的多次测量,检验了探测系统的稳定性。 英文
我们已做了大量的测试证实,在这种脉冲高度范围内,中子谱仪不会对像热中子这样的其他辐射源优先响应。特别是,我们企图通过使用多种γ射线、中子源和开/关辅助设备来产生赝2.5 MeV中子“信号”的努力都失败了。在所有的信号和本底运行中,我们关闭了像范德格拉夫加速器这样的中子产生装置。 英文
许多本底运行是用含标准电极和电解质的正在运行的电解池(下文将介绍)完成的,只是将其中的D2O换成了H2O;而其他的本底运行是用新的和之前用过的包含D2O和平常电解质的无电流标准电解... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 高斯拟合后,有一个峰,其中心在101道附近,其标准偏差是28个通道,幅度为23.2±4.5个计数。根据光谱仪校准,该特征峰的位置和宽度对应于2.5 MeV中子的期望值。在本底之上出现的显著信号对应的能量恰为d–d聚变的中子能量(约2.5 MeV),这一事实为电解质催化电解池中存在反应率很低的核聚变提供了强有力的证据。 英文
图3.通过从信号中减去定标的本底得到的差分谱图。图中给出每8个通道的统计误差(±1σ)。 英文
测定聚变率
对列入上文讨论的综合数据中的那14次运行分别进行考查是有益的。这些运行是在1988年12月31日至1989年3月6日期间完成的。图4给出了每一次运行在2.5 MeV的能量区域内的信号计数率与本底计数率之... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
通过改变诸如压强、温度和电磁场等外部参数,或许可以影响聚变的有效率,但是这种影响被看作是冷核聚变的另一种形式,即μ子催化聚变[13]。 英文
结论
关于冷压核聚变[1]的有关想法以及对存在于金属和地球地热区中的过量3He的观测,促使我们对电解池中的聚变进行了实验研究,该研究始于1986年5月。我们的电解质成分演变发端于地球化学的考虑,并且随着观测到结果而逐渐加以改变。虽然产生率波动很大,但聚变中子信号的出现一再被重现出来。既然我们的探索性研究已经揭露了一个小的压核聚变效应,接下来就要弄清影响聚变率的各种因素。 英文
我们的数据清楚地表明了需要远离平衡态条件的要求,并且该要求提示那些不同于电化学的方法也许同样可行。我们已经开始探... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | and conclude, therefore, first that the 2.22-MeV γ-ray confirms that the fusion process (2) is occurring, and second that a neutron production rate of the order of 4×104 neutrons s–1 is derivable from their γ-ray signal rate. They further state that most of the heat generation occurs not through process (2), but throug... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | obtained from Utah News Clips, Inc., Utah. As far as we can tell, all spectra are identical to that of Fig. 1b.) This spectrum was obtained in the course of the Fleischmann et al. experiments (M. Hawkins, personal communication). Their spectrometer system consisted of a Nuclear Data ND-6 portable analyser with a 3 in. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Here ΔE is the full width at half maximum (FWHM) of the line, E is the energy of the photon and R(En) is the measured “reference” resolution at energy En. R(En) can be accurately determined using a 60Co source (that is, the 60Co line at 1.33 MeV), or it can be fairly well approximated by the 40K decay line at 1.46 MeV.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | MeV) (R. Hoffman, personal communication). But we know from Table 1 that the spectrometer used by Fleischmann et al. has a resolution that is at best comparable to our own for the entire region from 1.46 to 2.61 MeV (see also Fig.1), so it is inconsistent that their linewidth at 2.22 MeV is a factor of two below the pr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | We also point out that in our (Pu/Be) neutron-capture experiments, a conspicuous e+–e– annihilation single-escape peak exists at 1.71 MeV (Fig. 3), as well as a double-escape peak at 1.20 MeV. (The full spectrum from the Pu/Be experiment, as well as the background spectrum, can be found in ref. 5.) Such features unambi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | factor of 200 rather than 50.) While differences in rates of a factor of two might possibly be explained by geometrical considerations, a factor of 50 is inexplicable. 中文
A further point concerning the identification of the signal line is the precise value of the energy at which the peak occurred. From Fig. 2, the back... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | R. D. Petrasso, X. Chen, K. W. Wenzel, R. R. Parker, C. K. Li and C. Fiore
Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
References:
Fleischmann, M., Pons, S. & Hawkins, M. J. electroanalyt. Chem. 261, 301-308 (1989); and errata.
Hamermesh, B. & Culp, R. J. Phys. Rev... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 这一质疑引发了人们对冷核聚变的报告中存在欺诈的首次怀疑,而不仅仅只是对简陋实验的质疑。 英文
弗莱施曼、庞斯和霍金斯[1]最近宣称在他们的冷核聚变实验中观察到了明显的放热现象,他们将这一结果归因于大量的聚变反应。作为核聚变发生的强有力的证据,他们在报道中说发现了2.22 MeV的γ射线,该射线源于氢原子核对中子的捕获[2,3]
n + p → d + γ(2.22 MeV)
(1)
(其中d代表一个氘核。)他们认为反应(1)中的中子产生于下述反应
d + d → n + 3He
(2)
由此得出如下结论:首先,2.22 MeV的γ射线证实了核聚变过程(2)的发生;其次,量级为每秒4×104个中子的中子产生速率可以由他们的γ射线信号的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 放射出具有一定能量的α粒子,α粒子与铍通过(α,n)反应产生中子(参考文献4、9)。中子在水中达到热平衡,我们通过我们的γ谱仪对产生的中子捕获γ射线进行观测。测量的分辨率在2.22 MeV处约为5%(表1a),这一分辨率可以通过方程(3)合理地预测出来。因而,这立即引出了弗莱施曼等人的信号线作为γ射线峰的验证问题。具体来说,图2表明信号线具有2.5%的分辨率。这是在从40K的衰变谱峰(1.46 MeV)或者60Co源(1.33 MeV)获知的分辨率(表1b)的基础上根据方程(3)计算出的分辨率的二分之一(霍夫曼,个人交流)。但是我们从表1知道,弗莱施曼等人使用的γ谱仪分辨率在1.46 MeV到2.61 MeV的整个范围内至多与我们的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 因此,我们质疑图2中γ谱的谱峰可能位于2.5 MeV处而不是在2.22 MeV处。 英文
对弗莱施曼等人声称的特征峰进行正确分辨的重要性再怎么强调都不为过。然而,非常遗憾的是在他们发表的图1a中仅展示了1.9 ~2.3 MeV的能量范围,却没有提供40K(1.46 MeV)和208Tl(2.61 MeV)的特征峰作为支持的证据,而为了证实他们的观点是正确的,这些峰本应出现在他们的谱图中。 英文
因此,尽管弗莱施曼等人可能在他们的γ射线光谱中观察到了某种由探测器位置改变所造成的变化,但正如之前人们所提出的那样[11],我们认为那与2.22 MeV的中子捕获γ射线并无关联,也与本底的谱线(2.20 MeV;图1a)无关。除了认为可能是仪... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | More than 3,000 RFLPs have been identified to date, including some 100 highly polymorphic loci at which dozens of variant alleles are present in the population. By using RFLPs to trace the inheritance of chromosomal regions in families afflicted with genetic disorders, human geneticists have been able to pinpoint the l... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | DNA diagnostics requires simply identifying whether each parent has passed to a child the RFLP pattern inherited from his or her mother or father. Because the four discrete patterns are known in advance, these investigations have built-in consistency checks which guard against many errors and artefacts. 中文
DNA fingerpr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | homogeneously mixed populations, without significant subgroups, even when considering loci at which most alleles are relatively young from the perspectives of population genetics. 中文
Yet despite such fundamental uncertainties, forensic labaratories blithely cite breathtaking frequencies: a recent report based on the st... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | On 5 February 1987, Vilma Ponce and her 2-year-old daughter were stabbed to death in their Bronx apartment. Acting on a tip, police interrogated a neighbourhood handyman, Jose Castro. Detectives noticed a small bloodstain on Castro’s watch, which was sent for analysis to Lifecodes. Company scientists extracted about 0.... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Fig. 1. Hybridization of probe 29C1 for the locus DXYS14 to Pst1-digested DNA from deceased mother (M), blood speck from defendant’s watch (W) and deceased daughter (D), performed by Lifecodes in New York v. Castro. Although the autoradiogram shows three bands in lane M, five bands in lane W and one band in lane D, Lif... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Lifecodes’ discounting of the two non-matching bands in the watch lane suggests that its identification of bands may have been influenced by making direct comparisons between lanes containing different DNA samples, rather than by considering each lane in its own right. Additional support for this hypothesis is provided... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | D2S44 and D17S79: declaring a match. To obtain objective measurements of a band’s position, Lifecodes uses a computer-digitizing apparatus3-5. The approach is reported to be highly accurate: when identical fragments are electrophoresed in different lanes, the difference between their positions is reported to show a sta... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Why then was a match declared? Lifecodes stated that it did not actually use the objective threshold of 3 s.d.s. for declaring a forensic match: its decisions were based on subjective visual comparison. Agreeing that the explicit statements in the forensic report implied that the objective criterion had been used, Bair... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | (3) Baird then explained the absence of a positive signal in the now-male control lane by telling the court that the male scientist has a “short” Y chromosome which “does not react with this repeat sequence”, a condition which is “fairly rare, but it does happen”. In conventional genetic terminology, the individual was... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | D2S44: Analysis of degraded DNA. Based on seeing only a single band in the watch DNA, the sample was reported to be homozygous for a 10.25-kilobase (kb) band at the D2S44 locus. Although the conclusion may seem reasonable at face value, there is a serious problem: the small quantity of DNA on the watch was clearly degr... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Probe contamination. To explain various artefacts, Lifecodes invoked four separate instances of probe contamination: human probes were said to be contaminated with bacterial sequences, and bacterial and plasmid probes were said to be contaminated with human sequences. Moreover, Baird testified that the company continue... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | ■ To declare a forensic match with a given band, Lifecodes’ published matching rule calls for examining a range of ±3 s.d.s around the band. Obviously, the chance of a match arising at random is just the proportion of bands in this range. 中文
■ To calculate the probability of a matching band occurring by chance, however... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | the true chance of a forensic match occurring at random, as it takes no account of the actual threshold used for declaring matches. 中文
Heterogeneity within the Hispanic population. To justify applying the classical formulas of population genetics in the Castro case, the Hispanic population must be in Hardy–Weinberg equ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | In fact, Lifecodes’ population study5 is scientifically valuable. From an evolutionary point of view, highly polymorphic loci contain many young alleles which may not be uniformly distributed within the Caucasian, Black or Hispanic populations. Studies of RFLP frequencies can reveal the detailed substructure of the hum... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | DXYS14; (2) declaring a match between bands at D2S44 and D17S79 whose measured positions differed by more than Lifecodes’ announced threshold of 3 s.d.s; and (3) using a less-strict matching rule when declaring forensic matches than when searching the population database. (Baird was unable to attend the experts’ meetin... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | In the end, the prosecution’s rebuttal case consisted only of the contention that the DYZ1 sex-test hybridization had actually worked correctly—based on the fact that Lifecodes had located another experiment done on the same day which showed a male-specific band in a rape suspect. (This would be an adequate, if unortho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Fig. 2. Hybridization of probe pAC256 for the locus D17S79 to Pst1-digested DNA from defendant (D) and semen sample (S), performed by Lifecodes in Georgia v. Caldwell. 中文
Although the hearing had been expected to last only a week, prosecutors asked for a month-long delay to prepare their rebuttal. Observers speculated... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | In New York v. McNamara in November 1988, another Bronx defendant sought to prove his innocence with DNA fingerprinting. Assistant district attorney Renee Myatt opposed the request, telling the court, “the office policy in dealing with a particular agency that does testing with respect to DNA [is] that their testing ha... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | As it happens, the woman later gave birth to a full-term baby girl on October 24—conceived on about January 29, according to sonograms carried out by her obstetrician. In view of the apparent contradiction, Cellmark last week invited a group of outside scientists to reanalyse remaining DNA samples from the baby. 中文
Set... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Cooke, H. Nature 317, 687-692 (1985).
Baird, M. et al. Am. J. Hum. Genet. 39, 489-501 (1986).
Baird, M. et al. Adv. forens. Haemogenet. 2, 396-402 (1988).
Balasz, I., Baird, M., Clyne, M. & Meade, E. Am. J. Hum. Genet. 44, 182-190 (1989).
Cavalli-Sforza, L. L. & Bodmer, W. F. The Genetics of Human Populations (Sinauer,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
冒昧地说,法院的这个做法太草率了。虽然DNA指纹图谱技术作为法医学工具有着巨大的潜力,但是法院的仓促决定忽视了非常关键的两点:第一,DNA指纹图谱的技术要求比DNA诊断要高得多;第二,科学界尚未就如何确保该证据的可靠性达成统一的标准。 英文
DNA诊断只需要简单的鉴定父母双亲是否将他们从自己父母那里继承的RFLP图谱遗传给他们的子女。由于四个独立的样本图谱已经预先得知,这些检查可以通过一致性检验来防止许多可能的错误和假象。 英文
相反地,DNA指纹图谱技术更像是分析生物化学。它必须要确定两个完全未知的样品是否一模一样。由于高度变异的RFLP位点通常与50~100个等位基因相关,这些等位基因产生的限制性酶切片段长度非常相似,准确... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 在生命密码公司亲子关系与法医学部门负责人迈克尔·贝尔德的证词中,他承认手表上的血迹样品的泳道中多出了两条没有匹配的条带,但他坚称这些多出的条带是“一种我们无法鉴定的非人类来源的污染物”因而不予考虑。 英文
图1.纽约卡斯特罗案中已故的母亲(M),被告手表上的血迹(W)和已故的女儿(D)的DNA在Pst1消化后所得片段与检测DXYS14位点的探针29C1杂交的结果。实验由生命密码公司完成。尽管放射性自显影照片显示M泳道有3条条带,W泳道有5条条带,D泳道有1条条带,生命密码公司却记录说在三条泳道的同一位置都有三条条带。放射性自显影照片曝光过夜;后续没有用该探针进行其他杂交或曝光实验。 英文
我认为,除非证明这些多余的条带在使用未被... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
那为什么还要宣称这些条带是匹配的呢?生命密码公司陈述说他们实际上并不是用3个标准差这一客观阈值来确定条带是否在法医学上匹配:他们的结果是基于主观的肉眼比较来决定的。法医学报告中明确的陈述暗示客观标准已被使用,贝尔德同意这一观点,同时他承认那份陈述“可能不是”公司实际操作的“最好解释”。就我看来,不管是在公司的科学文献还是法医学报告中,都没有提到过用肉眼识别匹配。很明显,人们对生命密码公司使用的匹配原则存在着非常明显的误解。 英文
鉴于以下原因,我认为肉眼识别匹配对DNA指纹图谱技术是不适合的:(1)许多等位基因的大小非常相似;(2)测量过程的精确性是已知的;(3)没有对匹配的客观定义,就没有有意义的方法来计算所谓的匹配偶然发生... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
尽管在一些类型的实验中允许使用被污染的探针,然而在我看来,这样做在DNA法医学中是不合适的。因为样品的来源未知并且经常被污染,(使用污染过的探针)很可能导致假匹配并且很难被识别出来。 英文
群体遗传学。在宣布一个法医学上的匹配以后,测试的实验室会计算该匹配在人群中偶然发生的概率,该程序分三个步骤:(1)对每对检测的等位基因,都要计算匹配条带在已统计的人口样本(在卡斯特罗案中,生命密码公司使用了一个美国西班牙裔数据库[5])中的发生频率;(2)对每个位点,都通过经典的哈迪–温伯格方程计算观测到匹配的基因型的概率[5,6]。该方程基于人群是自由混合并且没有异质性亚群这一假设;(3)根据位点基因型的连锁平衡(无关联)假设,对于完整的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
专家声明
四月底出庭作证后的第二天,我参加了在冷泉港举行的关于基因组作图的会议。会议的组织者之一——理查德·罗伯茨曾在二月中旬卡斯特罗案开始时出任检方的首席证人。罗伯茨解释说,他出庭作证只是想向法庭提供一种用于DNA分析的引物。考虑到已经暴露出来的问题,罗伯茨提出了一个新的计划:召开一个由控辩双方专家共同参加的联合科学会议来审查证据。 英文
在5月11日举行的会议上,专家们达成共识并发表声明,宣布“本案中DNA数据在科学上的可信度不足以支持这些样品匹配与否的论断。如果这些数据被提交至一份同行评审的刊物用以支持某个结论,它们是不会被接受的,而是会被要求进一步实验”。声明中特别引出了如下的不恰当之处:(1)未将DXYS14中多出的... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 法官拒绝撤销保释,被告在不离开本市的情况下依然无罪,并要求获取第三份血样。亚列姆科在向生命密码公司施压后说,该公司承认的确犯了个错误。内史密斯由于错误的DNA检测结果而险些失去自由,在其血液和精液样品被送至细胞标记诊断公司,证实了最初内史密斯的嫌疑被排除的结论后,他最终被判定无罪。(生命密码公司上周拒绝就此次事件做出评论。即使评论,也很可能就是些将样品搞混了之类的每个临床实验室都可能发生的事情。然而,鉴于许多陪审员都认为DNA指纹图谱是绝对可靠的,样品处理流程应该需要更严格的规定。) 英文
在1988年11月的纽约麦克纳马拉案中,另一位布朗克斯区的被告试图通过DNA指纹图谱技术来证明自己的清白。地区助理检察官勒妮·米亚特反对该请求,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | happen there—less extensively, but much closer to regions of dense population. Here atmospheric scientist David Hofmann and co-workers report the first confirmation of that, from observations made the previous winter. Arctic ozone depletion was regularly seen in subsequent years. 中文
Stratospheric clouds, believed to b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | towards Scandinavia on 24 January which was eventually followed by a major stratospheric warming on about 10 February (K. Labitzke, personal communication). Before the major warming, however, temperatures as low as –92°C were observed on 1 February at 30 hPa over southern Scandinavia. Temperatures below –85°C in the 20... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | At a pressure of 30 hPa and for a typical stratospheric water-vapour mixing ratio of 5 p.p.m.v., a temperature of ~ –87.5°C is required to condense the vapour and form ice clouds (the “frost point” temperature). However, studies of the nitric acid trihydrate (NAT) solid in the laboratory3 indicate that this crystalline... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The data were obtained with University of Wyoming balloon-borne particle counters as used on many occasions in Antarctica7. The optical counter has an air-sample flow rate of ~200 cm3 s–1, capable of resolving low concentrations (~10–3 cm–3) as associated with ice-crystal formation. The instrument measured in seven siz... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | minimum of –82.7°C at ~25 km. 中文
Fig. 2. Temperature and aerosol (r≥0.20 μm) profiles measured during balloon ascent at Kiruna, Sweden on 23 January (full lines) and 30 January (dashed lines) 1989. 中文
The aerosol profiles in Fig. 2 indicate a normal sulphate layer between ~10 and 18 km with concentrations similar to ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | the PEL (Physics and Engineering Laboratory, Lauder, New Zealand) group at the Swedish Institute of Space Physics Observatory in Kiruna during the measurement period. These low values are essential for the chlorine chemistry detailed in ref. 3 to occur. The second flight on 30 January, at somewhat warmer temperatures, ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | total ozone by the PEL group at Kiruna indicate a value of 330±25 DU on 23 January. The total ozone mapping spectrometer (TOMS) satellite instrument gave values of ~270 DU and 235 DU near Kiruna on the two days (A. Krueger, personal communication). 23 January was the first day for which TOMS had sufficient sunlight to ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | are compared in Fig. 4. The descent temperature profile has less structure because of the rapid descent rate in the stratosphere. Small fluctuations in the sulphate layer at 14 km, reproduced in the descent profile, further suggest little differential motion of the balloon and the 15–20-km stratospheric air mass. The d... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 1988 (ref. 15), a very high degree of supersaturation would have had to exist. It is quite likely that neither of these conclusions is correct by itself but that this air parcel had been somewhat denitrified and that the cold layer at 21 km was caused by a recent rapid cooling. 中文
To address this issue further, we may ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | N0, σ and r0 are respectively the total number concentration, the distribution width and the mode radius of a log-normal size distribution.
† HNO3 vapour mass from assumed nitric acid trihydrate composition, density=1.62 g cm–3. 中文
We now turn to the issue of possible ozone depletion in the 22–26-km region, where the m... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | As mentioned earlier, although stratospheric sunlight in late January is insufficient for the photochemistry required for ozone depletion over much of the Arctic, this is not the case at Kiruna, near the Arctic circle, especially if slightly non-zonal flow increases the time air parcels spend in sunlight, as was the ca... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | several degrees higher in the sky at local noon at Kiruna than at McMurdo whereas the daily increase of sunlight hours is slightly faster at McMurdo than at Kiruna. 中文
Figure 5 shows ozone partial pressure and mixing-ratio profiles covering this period at McMurdo in 1986, 1987 and 1988. McMurdo was in a favourable posi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | The amount of the apparent ozone deficit observed in the Arctic is very small. If the mixing-ratio curve on 23 January is filled in so that the depression between 22 and 26 km does not exist, and the total ozone is then calculated, a value only 10 DU, or ~3%, higher is obtained. In more normal, relatively cloud-free ye... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Toon, O. B., Hamill, P., Turco, R. P. & Pinto, J. Geophys. Res. Lett. 13, 1284-1287 (1986).
Crutzen, P. J. & Arnold, F. Nature 324, 651-655 (1986).
Fahey, D. W. et al. J. Geophys. Res. 94, 11299-11315(1989).
Hofmann, D. J., Rosen, J. M., Harder, J. W. & Hereford, J. V. J. geophys. Rev. 94, 11253-11269(1989).
Hofmann, D... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 北极并不存在如此稳定的极涡,然而有人怀疑臭氧亏损仍可能发生在那里——范围更小,但更接近于人口密集的区域。本文中大气科学家戴维·霍夫曼和他的同事们通过前一个冬季的观测结果首次证实了北极臭氧亏损。在随后几年中,北极臭氧亏损定期出现。 英文
平流层云被认为是春季极地臭氧亏损发生的必要条件,1989年1月我们利用气球运载的探测仪探测了瑞典基律纳地区的平流层云,这个1月是至少25年来北极平流层最冷的1月份。对比南极地区麦克默多站上过去三年的春季臭氧廓线与云层所在区域的臭氧廓线,我们认为臭氧亏损的起点位于海拔22~26 km处。 英文
在南极地区,平流层云在春季臭氧亏损中的作用已经得到公认,但到目前为止,它在北极地区的作用仍尚未明确。本文中... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 该设备测量了7个尺寸范围:粒径r≥0.20 μm、0.25 μm、0.30 μm、1.0 μm、2.0 μm、3.0 μm和5.0 μm的球形粒子或等效体积的略呈非球形的粒子。在1月30日进行的第二次飞行中增加了凝结核探测器,它可以探测到粒径r≥0.01 μm的粒子,以获取总气溶胶浓度廓线,并确定云粒子生长过程中凝结核所占的比例。 英文
图2给出了两次飞行中气球上升期间获得的温度及r≥0.20 μm的气溶胶廓线。1月23日探测到,海拔18.5~27 km的温度低于–80°C,20.2~21.3 km温度低于–85°C,在23~25 km温度也几次达到–85°C。由于气球所处的温度极低,因此其上升速度也比较缓慢(1~2 m·s–1),... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 根据过去在南极麦克默多的经验,9月初,在受到阳光照射的第一天,TOMS的观测值要比臭氧无线电探测仪数据计算出的值低10%左右,之后会接近到百分之几以内[13]。12~18 km处臭氧的大幅波动类似于观测到的准水平平流,这些平流可能来自于其他纬度[14]。然而,从1月23日到1月30日,22~26 km处的臭氧减少量由25%左右下降到了10%左右,这似乎有些异常。这种明显的臭氧亏损与南极9月初臭氧亏损的起始阶段极为相似,下文将进行讨论。 英文
图3.1989年1月23日(a)和1月30日(b)在瑞典基律纳测得的臭氧分压与混合比廓线。 英文
讨论
假设云层粒子是由NAT组成,那么脱氮作用的问题可通过云层粒子观测结果来回答,该作用是臭... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 鉴于这一高度上极涡的强度和组成性质,我们认为不存在其他纬度地区的贫臭氧空气的输送。尽管在南极地区,当8月末臭氧开始亏损之前并未观测到类似低值,但并不能排除低值是北极臭氧分布的永久性特征的可能性。1月30日出现的臭氧减少有可能是20 km和26 km之间主要的垂直运动的结果,因为该区臭氧的混合比相对比较稳定;但温度廓线看上去并不是如预期那样在该高度段上呈绝热变化的。另一方面,1月23日在21~24 km处的臭氧混合比例随高度升高而降低,表明该段是一个天然臭氧吸收汇。臭氧出现亏损的高度与1月23日观测到的小粒子大幅度增加的高度并不完全一致,但与在1月23日和30日都曾观测到的低浓度的、大的、可能老化的粒子所在区域却是一致的。1月23日观... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 英文
(齐红艳 翻译;安俊岭 审稿)
A Membrane-Targeting Signal in the Amino Terminus of the Neuronal Protein GAP-43
M. X. Zuber et al.
Editor’s Note
Growth-associated protein 43 (GAP-43) is a neuronal protein expressed in high levels in growth cones, specialized structures found at the end of growing nerve fibres that help guide them... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | found that the cysteines in the N-terminus are fatty-acylated and that this post-translational modification correlates with membrane-binding ability. We investigated the binding of GAP-43 to the growth-cone membrane by mutational analysis and by laser-scanning confocal microscopy of fusion proteins that included region... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | association in brain14. Thus, the N-terminus of GAP-43, especially its N-terminal cysteine residues, seem to be necessary for the binding of GAP-43 to membranes. 中文
Fig. 1. GAP-43 N-terminal mutations prevent membrane association. COS cells were transfected with the expression vector pGAP (GAP) or with plasmids contai... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | To determine whether the N-terminus is sufficient to confer on GAP-43 the ability to bind to membranes, we made constructs that encoded differing amounts of the GAP-43 N-terminus fused to a reporter peptide, and expressed them in COS and PC12 cells. We chose chloramphenicol acetyltransferase (CAT) as the reporter pepti... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | indicated by the asterisks. b. Membrane association of GAP and GAP40CAT in PC12 cells. Stably transfected PC12 cells expressing CAT, GAP40CAT or GAP were selected as described below. Immunoblots of membrane (M)-and cytosolic (C) fractions were stained with anti-CAT antibodies (left panel) or anti-GAP (right panel) anti... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | During selection of PC12 cells, 400 μg ml–1 of active Geneticin (GIBCO) were used. Transient transfection of PC12 cells was by electroporation with the BioRad electroporation system using 300 V and 960 μF. After 8 h the medium was changed. Twenty-four hours after electroporation the cells were plated on poly-D-lysine-c... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | electrophoretically transferred to nitrocellulose and excess sites were blocked with 4% BSA. Membranes were then incubated for 24 h at 4°C with 40 μg ml–1 affinity-purified anti-GAP, or a 1:1,000 dilution of anti-CAT antibodies. Bound antibody was detected using anti-rabbit horseradish-peroxidase method (Vectastain) ac... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 10 amino acids (GAP10CAT) were fused to CAT, the immunofluorescent distribution resembled that for GAP-43, including enrichment in growth cones. All cells were treated with NGF for 24 h before fixation. Anti-CAT antibody was used for a, c, and d, whereas anti-GAP-43 antibody was used for b. Control PC12 cells of this v... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Methods. For high resolution confocal microscopy, the cells were fixed with freshly made 4% paraformaldehyde and 0.5% glutaraldehyde, which was essential to preserve the fine structure of the filopodia, and then with 0.1% Triton X-100 for 3 min and 2 mg ml–1 sodium borohydrate in PBS for 10 min. Confocal analysis used ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | similar or identical binding sites must be present in other cells types. However, because GAP-43 is neuron-specific, these sites would presumably be targets for different proteins in non-neuronal cells. Sorting and selective transport, however, are as likely to account for growth-cone accumulation31 as is the existence... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Karns, L. R., Ng, S.-C., Freeman, J. A. & Fishman, M. C. Science 236, 597-600 (1987).
Cimler, B. M., Andreasen, T. J., Andreasen, K. I. & Storm, D. R. J. Biol. Chem. 260, 10784-10788 (1985).
Perrone-Bizzozero, N. I., Weiner, D., Hauser, G. & Benowitz, L. I. J. Neurosci. Res. 20, 346-350 (1988).
Oestreicher, A. B., Van ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | Acknowledgements. We thank D. Goodman and L. Karns for help with plasmid construction, D. Rosenzweig and A. Pack for technical assistance, J. Garriga, R. Horvitz, P. Matsudaira and M. Shafel from MIT and J. White from the MRC for assistance with and access to confocal microscopy , and J. Jackson for preparation of the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 来自大鼠大脑(BR)的细胞膜粗提取物显示,有一条带的免疫染色与GAP转染COS细胞的条带具有相同的相对分子量(Mr)。星号指明了蛋白分子量标记的迁移位置,分子量分别为116K、84K、58K、48.5K、36.5K和26.6K。
方法。GAP-43中的点突变产生于pGAP制造的单链DNA,并用来将半胱氨酸转化为苏氨酸。寡核苷酸链GGCATGCTGACCTGTATG、ATGCTGTGCACTATGAGA和GCAGGCATGCTGACCACTATG-AGAAGAACC被分别用来使第3位半胱氨酸突变为苏氨酸,使第4位半胱氨酸突变为苏氨酸,以及使第3位和第4位半胱氨酸突变为苏氨酸。突变形成后,一个含有突变的长200碱基对(bp)的片段被亚克... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 电穿孔24小时后,将细胞置于多聚赖氨酸包被的盖玻片上,培养液中NGF浓度为50 ng·ml–1,并在24小时后分析。为了进行免疫组化实验,用包含大鼠GAP-43的氨基酸残基1~24、35~53、53~69以及212~228的4个肽段免疫兔子,以制备兔源抗GAP-43抗体。在GAP肽琼脂糖上亲和纯化抗GAP-43抗体。通过溴化氰方法使含有10 mg·ml–1的每一多肽的树脂与琼脂糖耦联,再使抗GAP抗体结合到这一树脂,并在pH 3.5的条件下洗脱抗体。从5 Prime-3 Prime公司获得兔源抗CAT抗体。从欧加农泰尼克,杰克逊免疫学和载体实验室获得二级抗体。为了提取细胞各种组分,从长满细胞的直径100 mm培养皿上刮下COS或PC... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | 两幅图的比较显示,特别是丝状伪足被染色。类似的结果也见于GAP10CAT(数据未展示)。比例尺为5 μm。
方法。为进行高分辨率共聚焦显微分析,用新鲜配制的4%多聚甲醛和0.5%戊二醛固定细胞,后者对于保存丝状伪足的精细结构来说是必需的,然后用0.1% Triton X-100处理3分钟,并用含2 mg·ml–1硼氢化钠的PBS溶液处理10分钟。使用BioRad MRC-500扫描共聚焦成像系统和蔡司Axioplan 显微镜做共聚焦分析。 英文
因此,GAP-43的前10个氨基酸足以指导它在细胞中的分布。虽然至少有一个在生长锥膜中积累的非整合蛋白,SCG10(参考文献17)有两个邻近的半胱氨酸(在位置22和24),但我们没有发现含... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | transcription in many eukaryotes—and the bicoid DNA-binding domain. 中文
The maternal gene bicoid (bcd) determines pattern in the anterior half of the Drosophila embryo. It is reported here that the injection of bcd– mutant embryos with messenger RNAs that encode proteins consisting of heterologous acidic transcriptiona... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | is a repeat that is found in the paired gene product3; this repeat is a sequence of~30 amino acids, rich in histidine and proline, which is also present in other gene products in Drosophila. The function of this repeat, however, is unknown. The C-terminal part of the Bcd protein contains an acidic region (residues 347–... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0305. 《自然》百年科学经典(英汉对照版)(第七卷)(1985-1992).epub | .epub | 41,865,664 | 2025-09-26T19:07:39.767346 | gene31-34. Other classes of activating sequences have been described35,36; none of these, to our knowledge, has been shown to function in many different eukaryotic cells as do the acidic sequences, and some of them have been shown to work only in restricted cell types36. 中文
Here we describe experiments that show that t... | 400套付费套装书 |
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