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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 | translated, as revealed by immunohistological stainings of the injected embryos for Bcd protein (data not shown). The reporter DNA might enter the nuclei during the rapid syncytial nuclear divisions and the hb-CAT fusion gene is transcribed under the control of the Bcd protein10. About 3 h after injection, at the onset... | 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 yeast strain used in these experiments is derived from GGY1 (ura3, leu2, his3, Δgal4, Δgal80) (ref. 46) by integrating at the URA3 locus a modified GAL1–lacZ fusion gene. The plasmid pMA630R, which was used to generate GGY1:: MA630R, was constructed by inserting the HindIII–MluI fragment from the plasmid hbCAT-298 ... | 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 β-gal activity expressed from the third transfected plasmid pPAclacZ (ref. 10). For the assays in yeast and Schneider cells, synthesis of the various Bcd proteins was tested by immunoblotting analysis (Fig. 1). For Drosophila embryos, mRNAs coding for Bcd protein or its deletion derivatives were transcribed in vitr... | 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 | cells. However, the results are obscured somewhat by our lack of knowledge of protein levels in the three test systems but, when taken with the results of the following section, indicate a correlation between the ability of a Bcd derivative to activate transcription in the embryo and its biological function as a morpho... | 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 | cells (see Table 2). The sizes of Mr markers (from BioRad) are (Mr×10–3): 130, 75, 50, 39, 27 and 17.
Methods. Procedures of preparing proteins from yeast and Schneider cells were as previously described10,51. For the yeast proteins in a, the yeast cells were grown in 10 ml synthetic minimal medium (lacking leucine) wi... | 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 | used was GGY1:: MA630R. The assays were done in quadruplicate and the standard error was normally <20%. 中文
Morphogenetic Activities
We tested the morphogenetic activity of the Bcd deletion derivatives by injecting small mounts of corresponding in vitro-synthesized mRNAs into the anterior tip of embryos obtained from bc... | 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 | completely rescue bcd– embryos. We now show that Bcd (1–246), a derivative that activates transcription poorly in all three systems, can rescue bcd– mutant embryos when fused to heterologous acidic activating sequences. 中文
Table 3a. Rescue of bcd– embryos by Bcd and its deletion derivatives
中文
Table 3b. Rescue of bc... | 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 | identifiable structures are the third or fourth abdominal denticle belt. Usually the cuticles have a large hole at the anterior end, though in some cases (as shown) the anterior end is closed. c, Partial rescue with open anterior ends (class 4).The embryos develop, with a high variability, one to three thoracic denticl... | 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. See legends to Table 1 and Table 2 for a description of the expression vectors used in our study. The mRNAs, synthesized in vitro by Sp6 RNA polymerase50, were extracted with phenol-chloroform and chloroform, precipitated with ethanol, washed with 70% ethanol, and diluted in diethyl-pyrocarbonate-treated water... | 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 yeast cells more efficiently than does the N-terminal fragment of Bcd alone (Table 2). 中文
We tested the morphogenetic activity of the Bcd fusion proteins by injecting the respective mRNAs synthesized in vitro into the anterior tip of embryos obtained from mutant females homozygous for bcdE1. Three of t... | 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 | anterior to the thorax (class 4). The latter phenotype can be explained by a Bcd protein gradient with a much higher overall concentration throughout the embryo than that of the wild-type Bcd protein gradient. As Bcd protein determines positions along the anterio–posterior axis in a concentration-dependent manner5, ove... | 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 | assayed in all systems, compared with wild-type Bcd protein, and can only partially rescue bcd– mutant embryos. However, when fused to certain acidic activating sequences—peptides known to confer transcriptional activation in many eukaryotes—Bcd (1–246) fully rescues bcd– mutant embryos. 中文
Our results with Bcd deletio... | 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 | development, but when there are eight copies of the bcd gene in the female, the abdominal segmentation frequently is abnormal and the embryos may die (refs 4 and 5; T. Berleth and W.D., unpublished results). The “posteriorward” shift of position on the fate map with increased concentrations seems to be largely independ... | 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 | * Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Spemannstrasse 35/III, D-7400 Tübingen, FRG
† Department of Biochemistry and Molecular Biology, Harvard University, 7 Divinity Avenue, Cambridge, Massachusetts 02138, USA
Received 3 May; accepted 5 September 1989.
References:
Frohnhöfer, H. G. & Nüssl... | 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 | Kakidani, H. & Ptashne, M. Cell 52, 161-167 (1988).
Webster, N., Jin, J. R., Green, S., Hollis, M. & Chambon, P. Cell 52, 169-178 (1988).
Fisher, J., Giniger, E., Ptashne, M. & Maniatis, T. Nature 332, 853-856 (1988).
Ma, J., Przibilla, E., Hu, J., Bogorad, L. & Ptashne, M. Nature 334, 631-633 (1988).
Courey, A. & Tjia... | 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 | 德国生物学家沃尔夫冈·德里费尔和克里斯蒂安娜·福尔哈德早前已经揭示转录因子Bicoid(Bcd)在果蝇胚胎中以浓度梯度的形式存在,此梯度反过来影响其他身体形态建成相关基因的表达模式。本文中他们与分子生物学家马克·普塔什尼和马俊合作研究Bcd在形态发生方面的特性。缺失bicoid(bcd)基因的突变体发育出重复的后部结构但是缺少头部和胸部。但是这些胚胎可以通过注射某种信使RNA获得拯救,这种信使RNA编码一种融合蛋白,这种蛋白包含酸性转录激活序列(在许多真核生物中启动转录的多肽)和bicoid的DNA结合域。 英文
母体基因bicoid(bcd)决定果蝇胚胎前半部的发育模式。本文报道,将融合蛋白的信使RNA(mRNA)注入bcd–突... | 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 | 果蝇施耐德细胞中Bcd衍生物的活性是通过将细胞与一个报告基因质粒和一个效应基因质粒共同转染测定的,报告基因质粒中氯霉素乙酰转移酶(CAT)与hb基因融合,而效应基因质粒表达Bcd蛋白或它的一个衍生物。在胚胎实验中编码Bcd蛋白或其衍生物的mRNA在体外合成。然后与含报告基因hb-298CAT的质粒共同显微注射到bcdE1雌性纯合子的前极细胞期胚胎的前半部,bcdE1是bcd一个大片段缺失的强等位基因[1,4,22]。在注射过的胚胎中用胚胎免疫组织学染色检测Bcd蛋白(数据未显示),结果显示注射的mRNA被有效地翻译了。报告基因的DNA可能在快速合胞体核分裂期间进入核中,并且hb-CAT融合基因在Bcd蛋白控制下转录[10]。注射约3... | 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 | Bcd蛋白缺失C末端83个残基产生一个1~396个残基的衍生物,Bcd(1~396),它在酵母中激活转录的效率只有野生型Bcd蛋白的10%,但在施耐德细胞和果蝇胚胎中的效率为野生型蛋白的80%。衍生物Bcd(1~338)在施耐德细胞中丢失了大部分转录激活功能,但在果蝇胚胎中的转录激活效率为野生型Bcd的50%。衍生物(1~246)在三种体系中只能微弱地激活转录,Bcd(1~111)只包含三分之一的同源异型结构域,无活性。图1显示了在酵母和施耐德细胞中预期大小的蛋白的合成。然而,由于我们缺乏这三个检测系统的蛋白质水平的知识,这些结果有些不明朗,但当此结果与随后的部分结合,则表明一种Bcd衍生物在胚胎中激活转录的能力与它作为形态发生素的... | 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 | 在缺失衍生物中Bcd(1~396)和Bcd(1~348)也可以完全拯救突变表型。相反,Bcd(1~111)不能在任何方面拯救bcd–突变表型。衍生物Bcd(1~246)只能部分修复野生型模式:它抑制后部结构在前部的形成,高频率地诱导胸部结构发生,但很少出现头、唇、上颌或下颌的体节结构。但即使以高浓度注射(5 μg·μ1–1;表3a)衍生物Bcd(1~246)的mRNA,胚胎也从不孵化(见图2d)。用片段Bcd(1~246)mRNA注射的胚胎类似于两个含纯合的弱bcd等位基因bcdE5和bcd111(参考文献1)的雌性产生的胚胎,它们分别由259位氨基酸和257位氨基酸的琥珀型突变引起[22]。因此,我们的数据表明这个蛋白靠近C末端的... | 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 | A1–A8,腹侧腹齿带;ap,肛板;cs,头咽骨;DBr,背桥;DA,背腕;eps,额唇骨片;fk,filzkörper;LG,lateralgräte;lr,上唇;mh,口钩;ppw,后咽壁到腹腕;T1–T3,胸齿带;VA,腹腕;VP,垂直面[52]。 英文
Bcd融合蛋白
我们将Bcd片段(1~246)结合到(1)疱疹病毒重要的激活子VP16的酸性激活序列(411~491位残基)[40,41];(2)GAL4的酸性激活域II(768~881位残基)[28];(3)GAL4激活域II的一部分(851~881位残基)[28];(4)源于大肠杆菌的酸性激活序列B6、B17和B42(参考文献29)(图1)。与预期相同,在酵母细胞中这些... | 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 | 这些观察结果与以前的遗传学数据相符:母体含6拷贝bcd基因时产生的胚胎发育正常,但母体含8拷贝bcd基因时其胚胎腹部体节往往不正常并且胚胎会死亡。(参考文献4和5;T. Berleth和沃尔夫冈·德里费尔,未发表结果)。浓度升高导致囊胚发育图上的位置后移似乎与激活子强度没多大关系,因为弱激活子Bcd(1~246)也产生这个效果(数据未显示)。 英文
第二,Bcd衍生物的活性也可在一个特定范围内变化,并使胚胎发育为正常幼虫。例如,Bcd(1~348)和野生型Bcd蛋白,虽然它们的转录激活活性有2倍的差异(表1),如在果蝇胚胎中确定的,但它们都可完全拯救bcd–突变表型。 英文
我们的研究证明了Bcd蛋白在酵母细胞中通过hb上游元件激活... | 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 | component for this loss. 中文
MEASUREMENTS from the past few years have shown that stratospheric ozone decreases substantially over Antarctica during September and October and that these decreases have intensified dramatically during the past decade. The intensification has been attributed to man’s release of certain ch... | 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 | that it was not just a local phenomenon3. Measurements obtained from balloons provided snapshots of the vertical distribution of ozone at a few Antarctic locations and presented striking accounts of large ozone decreases when comparing profiles from August with those from October4,5. But the changes observed were not s... | 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 | a deviation from conservative behaviour that can be interpreted as a chemically induced change not within the standard gas-phase photochemistry. The formulations presented are first applied outside the region usually referred to as chemically perturbed. Then the analysis is used in a different manner, but this time bot... | 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 | Danielsen and Houben9 give heuristic arguments for wintertime diabatic cooling over Antarctica persisting into early spring, carrying ozone-rich mid-latitude air downward and poleward into the polar vortex. Proffitt et al.10 have presented supporting evidence from AAOE indicating a slow progression of diabatically cool... | 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 | quite restricted, extending only from the southern tip of South America to the region over or near the Antarctic Peninsula. Also, data were collected during the transit flights between Moffett Field, California (37° N) and Punta Arenas, Chile (53° S), where the twelve ER-2 Antarctic flights originated. 中文
Lower Limit f... | 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 | Southern Hemisphere balloon data taken by Galbally et al.14 up to 30 km have the same characteristic. This persistent linear relationship and lack of curvature results from a balance of photochemistry, transport and mixing. The N2O intercept and slope are probably determined in the tropics where upper tropospheric and ... | 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 | tropics where, at 20 km, stratospheric air is apparently encountered that had recent O3 production without the equivalent NOy production required for the usual ratio found at mid-latitudes. Other latitude surveys of ER-2 data taken during the Stratosphere Troposphere Exchange Project in January and February 1987 from 4... | 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 | underestimate the O3 losses that have occurred. 中文
Ozone Losses
On 17 August between 54°S and 63°S (Fig. 2a), there was a significant difference between the expected O3/NOy ratio (inequality (2)) and its measured value. As NOy was not perturbed and O3/NOy is less than our reference level of 270, an O3 loss is indicated... | 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 abrupt increase south of the boundary is due to the high degree of denitrification within the highly chemically perturbed region13 and provides little information on the O3 loss. We deal below with this region in a different way. However, outside the boundary where the NOy is known to be unperturbed relative to N2O... | 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 isentropic temporal changes in O3 outside the boundary during this one-month period are small in comparison with those inside, and in general are not significantly different from zero18. As discussed in the introduction, losses of O3 in a parcel of air undergoing diabatic descent will not be represented accurately ... | 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 | There is more uncertainty in applying inequality (3) inside the boundary where N2O<140 p.p.b.v. (see Fig. 1), stemming from our lack of information to support equation (1) and inequality (2) at these more southerly latitudes. Outside the boundary, equation (1) was used to test where NOy was perturbed, then inequality (... | 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 | b. The loss outside the boundary is typically 20–25% at 425 K for the first 5° with a maximum value indicated of ~30%. From Fig. 3 we obtained a maximum value of 30% O3 loss outside the boundary, which is virtually identical to the loss shown in Fig. 4c, although the analysis of Fig. 3 includes only seven of the ten fl... | 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 | mechanism for the chemical loss outside the boundary cannot be inferred from this approach, there is evidence of a temporal column O3 decrease over the past decade in this region, therefore indicating that the chemical loss that we report has an anthropogenic component. In particular, ref. 26 shows, by comparing satell... | 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 | sunlight the formation of polar stratospheric clouds (PSCs) outside the boundary can perturb chlorine and nitrogen chemistry, initiating catalytic destruction cycles. Observed temperatures are above the frost point on average, but low enough for PSCs to form that contain nitric acid, a component of NOy13,29. The NOy me... | 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 have analysed winter-time high-latitude O3 changes in a region where O3 is considered under dynamical control and standard gas-phase photochemistry is extremely slow. We have estimated a reference state for O3 in this region from other conserved trace species and compared this with measured values to determine a min... | 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 | Proffitt, M. H. et al. J. Geophys. Res. 94, 11437-11448 (1989).
Danielsen, E. F. & Houben, H. Anthropogene Beeinflüssung der Ozonschicht, 191-242 (DECHEMA, Frankfurt am Main, 1988).
Proffitt, M. H. et al. J. Geophys. Res. (in the press).
Tuck, A. F. J. Geophys. Res. 94, 11687-11737 (1989).
Kelly, K. K. et al. J. Geophy... | 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 | 在本文发表之前,对于由人类排放氯氟烃(CFCs)所引起的平流层臭氧破坏的观测仅限于极地地区,因为该区域的大气条件有利于观测。但本文中,科罗拉多州博尔德的迈克尔·普罗菲特及其合作者描述了在南极“臭氧洞”范围之外进行的臭氧亏损观测,这项观测于1987年在智利的一个观测站进行。他们并未确切给出氯氟烃或某些自然过程是否与这一地区的臭氧亏损有关,但是他们指出,这种亏损是由化学过程,而不是简单的由来自南极的臭氧含量稀少的空气稀释引起。这些发现表明,臭氧的耗损并不仅仅局限于无人居住的极地地区。 英文
本文利用1987年在智利蓬塔阿雷纳斯地区进行的南极臭氧空中实验中获得的数据,证明从8月中旬直到9月底任务完成时,在南极臭氧洞范围以外的高纬地区存在... | 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 | 普罗菲特等已证明,当极夜急流达峰值风速时,该边界略向极地偏移,这与利用卫星测得的臭氧柱总量在纬向上向极地急剧减少是一致的。此外,臭氧沿等熵面随时间减少(臭氧洞)的边缘至少在一个纬度(约111 km)以内。 英文
丹尼尔森和霍本[9]提出的观点具有启发意义,他们认为,冬季南极上空的非绝热冷却过程可持续至早春,并将富含臭氧的中纬度大气向下和向极地输送,进入极地涡旋。普罗菲特等[10]也从AAOE的实验数据中获得了支持这一论点的证据,即非绝热冷却过程非常缓慢,并且,当下行的平流层低层大气穿过极地急流进入臭氧洞时会向极地作平流螺旋运动。该观点与塔克[11]的观点有些类似,塔克也认为穿过极涡存在一个重要的质量流,但他认为起重要作用的是极涡内外... | 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 | 最南部纬度的值较低,并且在35°N附近有多个值低于300,这两点是两种航测的主要区别所在。两组数据均限于18 km到21 km之间的气压高度,并且都未包含边界以内的数据。两图中在大约55°S以北的所有纬度上O3/NOy都大于300,只有10月3日在加利福尼亚上空的航测中出现了几次较低值,低至260。在热带地区两种航测也都表现为比值的增大,因为在热带地区20 km高空上,显然会遭遇平流层大气,而其中O3刚刚形成,又没有相应量的NOy生成,达不到通常在中纬度地区见到的比例所要求的量。也有学者对1987年1月和2月的平流层对流层交换项目期间在40°N~30°S之间利用ER-2型飞机航测得到的数据作了分析(墨菲等,初稿准备中),结果表明,对... | 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 | 倘若认可这一结果(即,在上述位温条件下,一直存在着非绝热冷却过程并且很少发生向外混合作用)以及不等式(2),那么,从北侧向边界接近时,O3/NOy比值逐渐降低的现象不可能是由大气的垂直或水平输送与混合作用引起的,而必定是由这些高度上高化学扰动区外起作用的某些化学机制造成的。 英文
在这一个月内边界外O3沿等熵面随时间的变化小于边界内部,且一般位于零附近[18]。正如在引言中所说,在恒定位温下计算出的时间趋势无法精确地表示处于非绝热冷却状态的单个气团中O3的亏损量,因为臭氧的亏损可能会被O3的垂直梯度所遮蔽。所以,边界外缺乏明显等熵时间趋势绝不代表那里没有发生O3亏损。 英文
为了将我们的分析扩展至臭氧洞,从而检验两种方法的一致性,现... | 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
讨论与结论
臭氧洞最早于1985年发现,人们一直认为它是春季时期的一种循环事件,在近10年到15年的时间里其强度近于单调增加[25]。本文给出了早在8月中旬O3就显著亏损的有力证据,高化学扰动区内外都有,并指出该亏损的成因是化学作用而非大气动力作用的结果。虽然边界外亏损的化学机制无法根据此方法推断出,但有证据表明该区过去十年中O3柱总量是随时间降低的,这就说明我们所报道的化学亏损有一定的人为因素的影响。特别地,根据参考文献26,通过比较1979~1980年和1986~1987年的卫星资料,可以发现8月到9月里60°S至66°S之间O3柱浓度的下降值在这9年间从6%变到了18%。该区在AAOE实验期间位于边界附近,但平均来说是... | 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)
Upper Bounds on “Cold Fusion” in Electrolytic Cells
D. E. Williams et al.
Editor’s note
When electrochemists Martin Fleischmann and Stanley Pons claimed to have found evidence of “cold” nuclear fusion happening in a small flask of salty heavy water undergoing electrolysis, conflicting reports of ver... | 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 | understand in the context of the known interstitial-site separations (~3 Å), even more so when it is realized that this rate is a severe underestimate because of incomplete deuterium loading in titanium (see Materials characterization section). The reaction rates reported in ref. 1 are even more difficult to understand... | 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 used three types of calorimeter. First, we built calorimeters of size and design similar to those used by Fleischmann et al. (ref. 1 and M. Fleischmann, personal communication) (Fig. 1). We found these to be inaccurate instruments with some very subtle sources of error which it is necessary to appreciate and analyse... | 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. As well as the Fleischmann, Pons and Hawkins (FPH) type, we used10 two other calorimeter types—an improved heat-flow calorimeter (IHF) and an isothermal calorimeter. The IHF calorimeters differed from the FPH type in three important ways. First, they were larger: a 500-ml-capacity cylindrical vessel constitute... | 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 FPH cells we also used screened electrode contacts, but this had no effect on the results obtained. The IHF cells contained a Pd wire electrode insulated to the very tip, which was positioned about three-quarters of the way up the cell. This was used to define the internal liquid level during filling, or refilling,... | 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 | Materials Management, Las Vegas, Nevada, June 1988) comprises three concentric aluminium cylinders each separated by a heat transfer medium with a relatively low thermal conductivity. The cylinder temperatures are maintained by electrical heaters wound as helical coils around each cylinder. Temperature control is achie... | 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 | atmospheric pressure, F is the Faraday constant and I is the current (assumes ideal gases). 中文
Fig. 2. a, Raw data from FPH-type calorimeter containing a 4-mm Pd rod (1.5 cm long, Johnson Matthey “specpure”, drawn from sintered stock) in LiOH elctrolyte. Line 1 represents the output power calculated from the thermisto... | 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 | kc ≈ κA2/l = κA2/(l0 + IVmδt/(2Fπri2)) ≈ kc,0(1–αδt)
(Pin is the Joule input power, k is the calorimeter constant, ksb and kc are the contributions to the calorimeter constant of radiative losses through the vacuum jacket and conduction up the glass inner wall respectively, σ is the Stefan–Boltzmann constant, A1 is 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 | similar cell varied during the first part of a run. Because of this effect, we excluded the first 10,000 minutes of data from each cell when calculating the statistics. Table 1a shows the mean absolute power deviation for each cell and the standard deviation in this value. The standard deviation for all of the H2O cell... | 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 | g Specially produced material supplied by JM—prepared from cast Pd stock that was argon-arc melted into rod form using a gravity casting process. The rods were subsequently sliced and bent to decrease the loading time required (maximum distance from bulk to surface ~1 mm). The sample was cleaned using acetone, 10% HCl ... | 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 | of the H2O cells. If, however, the mean power deviation (Table 1a) for all eight of the D2O cells (+9.91±0.47% or 0.021±0.004 W; mean Joule input 0.96 W) is tested against that for all eight of the H2O cells (–2.46±0.72% or –0.018±0.004 W, mean Joule input 0.81 W for LiOH cells and 0.61 W for NaOH cells), it is clearly... | 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 other two types of calorimeters used in this study are described in Fig. 1 legend and results are given in Table 1b. We explored a range of different preparations of palladium and of current density, up to nearly 600 mA cm–2. With the improved heat-flow calorimeters (IHF), the sign and magnitude of the power excess... | 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 | arrangements) and any signal to be counted virtually simultaneously. In operation the cells were exchanged every 5 min, and the data from the 5 rings were recorded separately. Data from a typical run are shown in Fig. 3 as differences in the count rate between the powered and unpowered cell. Although in the particular ... | 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 | m Arc remelted twice; electrolytically charged for 1 month in 0.1 M LiOD then frozen in liquid nitrogen, dipped in concentrated Na2S solution and transferred to n-counting cell.
n Four 1–2-mm-thick discs of different types of Pd (Johnson-Matthey) spot welded to Pd wires plus strained Pd Wire.
o Electrolyte reused after... | 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 | aa For the present measurements, the system was calibrated with a set of standard γ-ray sources and a 238Pu/13C (α, nγ) source emitting 6,129-keV γ-rays. The cells were positioned such that their cathodes were as close as possible to the detector crystal, and the detection efficiencies were calculated by integrating 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 | rings, and because of the 135-μs-mean time to capture, neutrons emitted simultaneously from a source as a burst are counted separately (as seen with the 252Cf source, for example). The pre-amplifiers, high voltage components and insulators are all contained within a desiccated electrically screened box, and we eliminat... | 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 | promote deuterium loading into the cathode13 (see Fig. 3). As discussed later, we have not expressed the results in terms of the number of deuterium pairs within metal lattices. 中文
Because the net count rates given in Table 2 are differences between much larger background rates, runs were undertaken with a calibrated 2... | 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 | assumed that the ribbon would have had a high density of grain boundaries, dislocations and other lattice defects. Because the “on” and “off” periods were several times the characteristic diffusion time for the ribbon, it is assumed that the composition was cycling in the β-phase region between the fully loaded conditi... | 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 | stringent limit on the cold fusion process than do the neutron measurements. The interpretation of the results from some of these cells was complicated by the dissolution of gold anodes and the consequent gold deposition onto the cathode: this also would have affected the original work2. 中文
Tritium Enrichment
Fleischma... | 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 | where the total solution volume is maintained constant by the addition of fresh D2O (containing a mole fraction X0 of tritium, directly proportional to the disintegration rate), the ratio of the sampling rate of the solution to the electrolysis rate is α and γ denotes the ratio of the rate of evaporation of the solutio... | 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 | δS ≈ 0.02 would suffice. 中文
The applicability of equation (1) was confirmed experimentally, on both platinum and palladium cathodes, in conjunction with calorimetric and neutron-counting experiments (see Fig. 5 legend) using D2O with an initial tritium content of 13 kBq ml–1 (efficiency corrected). The fit of this equa... | 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 | With 125-μm palladium foils, hydrogen loadings (determined10 by hot-extraction mass spectrometry of specimens frozen in liquid nitrogen, and independently by electrochemical extraction) of H/Pd = 0.95 ± 0.05 were achieved in ~1 h at 100 mA cm–2 in 0.1 M LiOH solution with a platinum anode. The limit of deuterium loadin... | 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 | that microfissures, or rifts, develop in palladium to release the mechanical strains resulting from the heavy loading of hydrogen, together with the assumption that any such effect would depend on the stress state of the metal surface and its microstructure. 中文
Lithium was present in the surface layer on cathodes 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 | sample—(1–10)×1011 atom g–1. We found no 3He or 4He. The expected level, if fusion had been occurring at the rate reported in ref. 1, was ~1016 atom g–1. 中文
Evolution of hydrogen at a titanium cathode resulted, as is well known13, in a dense network of hydride precipitates, observable by standard metallographic methods... | 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 have attempted to minimize, by the shuttle procedure, uncertainty about background and counter variability and about error calculation. Given some of the more spectacular claims that have been made, we note that further caution is advisable because of the notorious sensitivity of 10BF3 and 3He proportional counters ... | 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 | experiment in the isothermal calorimeter a high current density was maintained for a considerable period (Table 1). Trace deposition of platinum on the cathode, supposedly causing a lowering of the overpotential for deuterium evolution and hence a lowering of the attainable deuterium level in the cathode, has also been... | 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 has been argued that the neutron branch of the d-d reaction might be completely suppressed in favour of the (t + p) branch and it has been further argued (S. Pons, personal communication) that the tritium produced as a result of a nuclear process inside the electrode need not necessarily exchange with the electrolyt... | 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 | Electrochemical Society Meeting, Los Angeles, May 1989). In discussing the claims in ref. 1, we prefer to focus on characteristics of the “simple” Fleischman, Pons and Hawkins (FPH) calorimeters, because we have only observed small effects (at the level of the inherent uncertainties), which might mistakenly be claimed ... | 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 | markedly with increasing temperature, the baseline slope would increase with increasing temperature and the effects of this sort of error would become correspondingly more marked: the claimed effects were indeed greatest in the cells run at the highest input power. Second, these calorimeters are nonlinear (equation (3)... | 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 feel that our work has served to establish clear bounds for the non-observance of cold fusion in electrolysis cells, under carefully controlled and well understood experimental conditions and using well characterized materials. Further details are given in ref. 10. Claims of observations of cold fusion ought now 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 | Kaufmann, S. & Libby, W. F. Phys. Rev. 93, 1334-1337 (1954).
von Buttlar, H., Vielstich, W. & Barth, H. Ber. Bunsenges phys. Chem. 67, 650-657 (1963).
Smith, D. P. Hydrogen in Metals (University of Chicago Press, 1948).
Carpenter, J. M. Nature 338, 711 (1989).
Gittus, J. & Bockris, J. Nature 339, 105 (1989).
Kreysa, G.... | 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 | 根据氘(即d)分子的核间距(0.74 Å)计算出的核聚变速率约为3×10–64 s–1(参考文献3),所以在已知间隙位间距(约为3 Å)的情况下,很难理解参考文献2报道的反应速率(每对氘核每秒约产生10–23次聚变效应),如果考虑到氘在钛中并未完全充满(参见材料表征部分),这一速率(约为3×10–64 s–1)还是被大大低估了,参考文献2中的速率就更不易理解了。而参考文献1中报道的反应速率甚至更难理解[4],尽管有强大的反对意见(如参考文献5),他们还是假定存在一种未知的机理,可以使反应速率异常增加,并抑制正常的核反应通道。 英文
第一批电解冷核聚变效应的报道指出,该效应并非自始至终都是可重复的,它耗时少许才出现并可能随后消失。因为... | 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 | IHF电解池中更大的电解液体积(300 ml)意味着重复添加仅需要偶尔进行,但是较大的热质则意味着响应会比较慢(时间常数约为12 小时):因此他们对热量的少量释放并不敏感。我们用置于填满油的玻璃管中的镍铬合金丝加热器对热流量热计进行了标定,该玻璃管与电解池的内容物相接触。标定的过程包括运行加热器,不施加电解电流或者施加显著小于(0.2~0.4倍)通常电解所需的电流,直到体系获得一个稳态的温度。对于FPH电解池,使用较小的电解电流旨在确保持续搅拌的同时减小由于基线漂移带来的误差;在每次单独的标定之前电解池都要再添加一次电解液。利用方程P = a–b(logR) + c(logR)2将得到的热敏电阻的阻值R在应用的功率P的范围内对P进行... | 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 | 倾斜的基线“简易的”FPH型量热计的响应可以模型化为[10]
Pin = kΔT=(ksb+kc)ΔT
(3)
其中[9]
ksb = σA1[Ti4–T04]/ΔT≈4σA1T03[1 + 3ΔT/(2T0)] = ksb,0(1 + 3ΔT/(2T0))
(4)
同时[10]
kc ≈ κA2/l = κA2/(l0 + IVmδt/(2Fπri2)) ≈ kc,0(1–αδt)
(其中Pin是焦耳输入功率,k是量热计常数,ksb和kc分别为通过杜瓦瓶内的真空夹层的辐射损失和沿玻璃内壁的传导对量热计常数的贡献,σ为斯特凡—波尔兹曼常数,A1为溶液与电解池壁的接触面积,T0为水浴温度,Ti为电解池的温度,ΔT = Ti – T0,... | 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 | 所有电解池都没有两个或者更多的连续数据点处于±2σ之外,D2O电解池实验中超出控制界限的数据点的数目与H2O电解池实验并无不同。因此,我们得出结论,在实验误差范围内,D2O电解池的特性与H2O电解池相比没有明显的异常。然而,如果根据表1a,将所有8个D2O电解池(+9.91%±0.47%或者0.021±0.004 W;平均焦耳输入0.96 W)与所有8个H2O电解池的平均功率偏差(–2.46%±0.72%或者–0.018±0.004 W,LiOH电解池的平均焦耳输入为0.81 W而NaOH电解池的为0.61 W)进行对比的话,其差别是十分明显的。因为没有一系列的独立数据点处于上述的控制界限之外,我们认为有另外一个未知的误差来源,与输... | 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 | 使用后分析了氢和氘——结果:H/Pd为0.02,D/Pd为0.83。
j 使用之前将箔浸入Na2S(浓溶液)中。使用后分析了氢和氘——结果:H/Pd为0.05,D/Pd为0.80。
k 将阴极切掉一半,使用后分析了氢和氘——结果:H/Pd为0.02、0.02,D/Pd为0.85、0.78。
l 熔体快淬带,由庄信万丰工程中心提供。
m 电弧熔化两次;在0.1 M LiOD溶液中电化学充氘一个月,然后在液氮中冷冻,浸入浓的Na2S溶液并转移到中子计数电解池。
n 包括点焊在钯丝上的四个厚度为1~2mm、不同型号的圆形钯片(庄信万丰公司)以及受到应力的钯丝。
o 之前实验的电解液重复使用,使用钛阴极和铂阳极。
p 使用之前将材料加热到9... | 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 | 如果我们假设发射至多持续了一个小时的时间,那么限值为,钯:7×10–2 n·s–1·g–1或4×10–2 n·s–1·cm–2,钛:8×10–3 n·s–1·g–1或2×10–2 n·s–1·cm–2(比用小颗粒的实验小得多)。中子发射速率限值比参考文献1报告的约104 s–1低数个数量级,比参考文献2报告的约0.4 s–1低一个数量级。值得注意的是,我们研究的限值也可以在那些冷核聚变可能会增强的电解池中得到,尤其是使用钛阴极,以大质量(40 g)的多孔颗粒来提高反应体积和表面积,而且特意选择能够促使氘吸附到阴极的电解液[13](见图3)。正如后面讨论的,我们没有展示氘在金属晶格中数目的结果。 英文
由于表2给出的纯计数率是大得多的... | 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 | 因此只有考虑这个已知的可变电解富集因素才能对弗莱施曼等人的宣称作出评估。令人惊异的是,弗莱施曼等人[1]宣称他们的铂电解池中没有电解富集。 英文
如果氢同位素的电解过程速率表述如下
其中r代表电解反应速率,S为氚–氘分配系数,X为氚(T)在溶液中的摩尔分数,那么氚的累积可以表示为[10]
其中通过添加新的重水(包含一定量摩尔分数为X0的氚,与衰变速率成正比)保持溶液总体积不变,溶液取样速率与电解速率之比为α,γ代表溶液蒸发的速率与电解速率之比——需要进行一个小的纠正,可以假设从电解池中溢出的电解气体在水蒸气中是饱和的。在目标时间尺度上,S的变化可以给出富集情况的变化
如果溶液被大气中吸附而来的氢污染了,那么如果Sobs代表由方... | 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 | 该层在螺旋状阴极的外侧要比内侧更容易观察到,而且在D2O中极化过的阴极上也比在H2O中极化过的阴极上更容易观察到(这可能与相同含量情况下Pd–D体系有更高的平衡气压有关),而且在不同来源的材料上其外观也不相同。这一发现可以用已有的理论[17]给予解释:由于充氢率很高,钯中将出现微裂缝和裂缝以释放掉由此而来的机械应力,同时也有假说认为这种效应依赖于金属表面的应力状态和它的微结构。 英文
在LiOD中使用的阴极表面层含有锂,通过二次离子质谱(SIMS)分析表明锂的浓度分布已经深入金属内1 μm。SIMS图像显示锂并不是规则分布的,而是看起来像被捕获在表面层中的微裂缝里。 英文
表面分析表明有一定数目的其他元素位于表面层之上或者其中,有极... | 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 | 在我们的中子计数实验中,新形成的位错是通过塑性形变产生的,一些计数实验是在高达1 A·cm–2的电流密度下进行的(表2),在使用等温量热计的一个实验中,其高电流密度保持了相当长的一段时间(表1)。痕量的铂在阴极上沉积,假设这会导致氘析出的过电压降低,从而降低阴极中氘可达到的浓度水平,也被认为是对不可重复性的一种解释(弗莱施曼,个人交流)。当我们在我们的中子计数实验中使用钯阳极时,并没有观测到任何效应。 英文
充氢和充氘的时间与预期的扩散时间一致(x2/D,其中扩散系数D = 10–7 cm–2·s–1,x为样品的半径或其厚度的一半)[10],并且核计数和量热实验进行的时间也总是远大于这一时间尺度。此外,在钯的电解充氘(氢)过程中,显... | 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 | 如果一个微分量热计常数通过输入功率来导出,计算出的输出功率应该为(来自图2的图注中的,方程(3))
Papp = kdΔT = (ksb,0 + kc) ΔT + 3(ksb,0/T0) (ΔT)2
与正确的输出功率(方程(3))进行比较,则有
Papp – P = 3ksb,0(ΔT)2/2T0
如果与电解功率相比,施加在加热器上的功率很大,那么这个误差会更大。从参考文献1给出的数据进行反演计算表明,声称的效应在焦耳输入功率为6 W的数量级时最大。对我们的FPH型量热计而言,这将得出ΔT≈50~60 °C。因此,如果这些电解池经过这种方法进行标定,将能观察到0.8~1 W量级的表观过热。我们的标定方法(见图1的图注)显著地减小了这... | 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 | mean temperature of up to 0.4 °C over periods of thirty years or more (see ref. 2, Fig. 1). Here we show how the ocean may produce low-frequency climate variability by passive modulation of natural forcing, to produce substantial trends in global mean temperature on the century timescale. Simulations with a simple clim... | 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 | magnitude of this low-frequency variability. 中文
Global mean temperature changes (ΔT(t)) in response to forcing ΔQ(t) can be modelled using an energy-balance model of the form9,10
In equation (1), φ (≈0.7) is a factor accounting for land/sea differences in heat capacity10, ρ is the density and c the specific heat capac... | 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 high-frequency response is therefore independent of the feedback parameter (and hence the climate sensitivity). This means that the response of the climate system to high-frequency forcings such as volcanic eruptions and the seasonal insolation cycle must be virtually independent of the sensitivity. High-frequency ... | 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 | Our aim is to determine the magnitude of the decadal to century timescale variations in global mean temperature under the constraint that they are compatible with the observed high-frequency variations. The model is therefore forced with random interannual variations in ΔQ; specifically, global mean gaussian white-nois... | 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 | of the parameters that control model output. 中文
The low-frequency character of the simulated global mean temperature variations that is of particular interest here is that around the century timescale, as this is particularly pertinent to the issue of greenhouse-gas forcing. This is in the frequency region in which 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 | autoregressive process described the temperature variations (as assumed, for example, in ref. 21), pointing to the importance of higher-order effects (see ref. 22). The 100-year trend confidence limits, although substantial, are much less than the observed trend of 0.5 °C over the past 100 years. In the sense that pass... | 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 | Table 1 also shows that the variability for a mixed-layer-only ocean (K = 0, W = 0) is appreciably greater than for non-zero K (as can also be seen from equation (4)). Simulations by Robock1 and Hansen et al.2, which are based on mixed-layer ocean formulations, have therefore probably overestimated the degree of low-fr... | 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 | T. M. L. Wigley and S. C. B. Raper
Climatic Research Unit, University of East Anglia, Norwich NR4 7TJ, UK
Received 4 January; accepted 9 February 1990.
References:
Robock, A. J. Atmos. Sci. 35, 1111-1122 (1978).
Hansen, J. et al. J. Geophys. Res. 93, 9341-9364 (1988).
Jones, P. D., Wigley, T. M. L. & Wright, P. B. Na... | 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 | 他们计算全球能量平衡时考虑了大洋环流的周期性模态,结果表明这些模态可以引起气温百年尺度的显著变化,但还不足以解释所有观测到的变暖幅度。 英文
全球平均温度的变化体现在多种时间尺度上。变化的原因通常可以分为外部原因和内部原因两种[1],而变化本身则可以分为低频变化(时间尺度年)和高频变化(时间尺度年)。事实上,对于内部原因所导致的低频变率,无论是其机理还是幅度,我们都一无所知。然而,从模式研究获得的证据表明,这种变率可能相当大[1,2],在30年或更长的时间范围中引起全球平均气温波动达0.4°C(见参考文献2,图1)。本文我们将展示海洋如何在自然强迫下被动调制并产生低频气候变率,从而产生世纪时间尺度的增温趋势的。我们还利用简单气候模... | 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 | 本文我们采用了一种抽象的地球气候模式,将地球分为南、北半球上的陆地和海洋“箱体”(见参见文献17)。为了便于与温室研究相比较,我们规定气候敏感度为大气CO2浓度加倍时大气的平衡温度,即ΔT2x为1.5~4.5°C,它与λ有关:
λ–1 = ΔT2x/ΔQ2x
(9)
其中,ΔQ2x取4.39 W·m–2(见参考文献18、19)。同时假定海洋中的垂直热传输为典型的涌升—扩散过程。 英文
我们的目的是要确定出,在与观测到的高频变率幅度相符的约束条件下,十年到百年尺度上的全球平均温度的变率大小。因此,本模式中给了一个随机的年际变率ΔQ,具体地说就是全球平均的高斯白噪音强迫。 英文
输入模式的强迫信号的总方差,需要与观测到的温度的高频方差(... | 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 | ‡ 90%的概率位于此界限内。 英文
从表1还可看出,在仅有混合层的海洋中(K = 0,W = 0),其温度的变化比K不为零时的值要大得多(从方程(4)中亦可看出)。因此,罗伯克[1]和汉森等[2]根据混合层海洋模式得到的模拟结果很可能高估了低频变化的程度,因为这种内部机制也会引起低频变化。 英文
上述结果与气候敏感度参数(即ΔT2x或λ)的值有直接关系,因此,也与检测温室效应对气候的影响问题有关。吉利兰和施奈德 [23]以及威格利和雷珀 [17]早就指出,倘若把观测到的气温变暖仅仅解释为温室效应的信号,将意味着气候的敏感性非常低,ΔT2x=1.3~2.0°C(该范围是由模式其他参数的不确定性造成的)。倘若将被动内变率考虑进来,则Δ... | 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 | from any of the cold-fusion cells over a period of 67 hours. 中文
PONS and Fleischmann1 claim to have achieved “cold fusion” of deuterium nuclei in electrolytic cells containing palladium cathodes and D2O (with 0.1 M LiOD) electrolyte, which produced excess heat of the order of a few watts. Their claim was based on 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 | Fig. 1. Side view of the geometry of the electrolytic cells and NaI detector, and top view of the cells with neutron-detecting sandwiches in place (thickline segments). Cells 2-1, 2-5 and 2-7 have palladium cathodes with diameters/lengths (in cm) respectively of 0.4/1.25, 0.4/10.0 and 0.1/10.0; cell 2-3 has a platinum ... | 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 | Spectral data accumulated by a pulse-height analyser were downloaded to a microcomputer every 0.5 or 1 h (live time) continuously over the five-week observation period, thereby minimizing the effect of integrated background on transient signals. The system’s gain was set so that γ-rays in the energy interval 0.1–25.5 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 | anomalous signals of duration <10–50 h would then appear in the residual spectra as positive excesses amidst Poisson fluctuations about zero. Signals of longer duration were searched for with even greater sensitivity by performing a similar operation on the collection of aggregate spectra. 中文
To correct for temporal va... | 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 | brought into the laboratory by other personnel. 中文
Fig. 3. Estimated rates for the four d + d fusion reactions. For each of the 1,114 γ-ray spectra obtained from data-collection episodes lasting 0.5–1 h, a residual spectrum was obtained by subtracting an averaged background spectrum from the signal. A fit was then mad... | 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 | Pd exposed to a beam of 3.02-MeV protons from a Van de Graaf accelerator (W. Schier, personal communication). Peaks at 0.37, 0.43 and 0.51 MeV are observed with their expected strengths. 中文
Table 1. Radiation yields of 3-MeV protons in palladium electrodes
中文
Fig. 4. Electric-quadrupole (E2) γ-ray lines from the iso... | 400套付费套装书 |
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