path stringclasses 189
values | ext stringclasses 1
value | size_bytes int64 569k 327M | mtime stringdate 2025-09-26 17:48:05 2025-09-26 19:10:03 | text stringlengths 40 2k | source stringclasses 1
value |
|---|---|---|---|---|---|
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | where the radiation energy density was high enough for scattering to be significant only within a sphere of radius ~0.1 pc. Nevertheless, if all the electrons are ejected from a massive object, their number density will be higher near the centre, and the amount of scattering will be greater there even if the radiation ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | variations amount to 10 flux units (and this flux cannot come from the halo), it is likely, though not certain, that self-absorption is in fact occurring.
中文
(3) The sense in which the emission rate of the gas in the shell varies as the additional radio energy falls on is must be known.
中文
(4) The relative intens... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | at 21 cm with a long base-line interferometer. Their proposed interpretation of their observations is that the source consists of two components separated by ~0.4 sec of arc, the angular diameter of each component being less than ~0.1 sec. This limit on the angular size of the components is still much greater than the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 为了简化模型,我们假设中心源由于其相对论电子流量的增加而发生变化,但是其角直径和磁场保持不变。如果该射电源极大时在高频的总流量密度增加一倍,那么中心源的流量则必须增加近10倍。因此,自吸收区最高频率v
b
可以由(v
b
/v
a
)2.5
约为10得出,即v
b
约为10,000 H
1/5
兆周/秒。
英文
下面,我们预估各种频率下可能观测到的时变。为了简化,我们假定中心源在高频区域按正弦变化。由于在v
> v
b
的区域不存在自吸收,因此实际观测到的时变应是正弦变化。在频率区间v
b
> v
> v
a
范围内,某频率处的流量密度首先按正弦变化增加,当达到自吸收阈值时就会停止增加,并保持恒定直至在后... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 而且,如果注入粒子速率的突然改变将导致S
(v
)在不同频率时的变化,我们可以预期在高频观测到的变化会比低频出现的早(即使不存在星系间散射[14]
)。
英文
在上文中,我们已经分析,如果核心区域在某频率(比如105
兆周/秒)发射大量的辐射,这些辐射一定主要来自对小于该值的频率范围不透明的某一球体。那么,该球体内频率小于105
兆周/秒的所有射电辐射的总能量密度约为6×10–3
尔格/厘米3
(在模型I中,该值约为10–6
尔格/厘米3
),这么高的密度值表明,逆康普顿散射可能起到了很重要的作用。在该辐射场中,能量为γm0
c
2
的电子的康普顿寿命为8×109
/γ秒。如果流量密度S
(105
)... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 由于自由电子的散射,这些气体对于所有频率的光都将是不透明的。如果变化的流量来自这团气体云中的一小块区域,则这种变化就会变得模糊不清并且难以观察,因此实际观测到的周期为数月的光度起伏会难以解释。如果气体云的密度分布是不均匀的,或具有丝状结构[20]
,则以上困难就会消失。然而,这样就会遇到另一问题,即如何将能量输入气体以平衡其损失。
英文
什克洛夫斯基曾经提出另一种结构[21]
,认为气体分布在一个薄球壳中。下面我们将采纳这一建议,并以射电变化为基础建立一个模型,从而可以同时解释长周期和短周期的光学波段的变化。
英文
不妨令该球壳的半径[21]
为4×1018
厘米,密度约为每立方厘米107
个粒子,总质量约为1... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 周期小于5年的变动则会部分消减,因此相应的起伏幅度会变小。
英文
观测到的光学波段的短周期光度起伏,时间周期为数月,而球壳的半径大约为4光年,因此这种短周期起伏显然不可能是由球壳内部产生的。在模型II中,认为这种短周期起伏是由于逆康普顿效应产生的。上文中已经提到,该模型中康普顿散射可以产生光,那么类似的原理也可以在这儿用于解释短周期起伏。这就要求散射必须发生于一个较小的区域(半径小于数光月)。然而,这种散射并不会集中于类似模型II那么小的区域(在模型II中,辐射能量密度足够高,因此使得散射主要集中在一个半径约为0.1秒差距的球形区域)。不过,如果所有的电子都是由一个大质量天体喷射出来的,靠近中心的粒子数密度自然会很高,那么即使... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | variants of a single character, then illumination of a character similar to any such variant can be made to produce a visual code easily readable by a machine. Gabor's basic idea, with many modifications, is now commonly used in pattern recognition techniques based on holography.
中文
W
AVE-FRONT reconstruction or ho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | be a combination of point-sources, forming a code-word which can be read by a machine. Produce the hologram by combining A
and B
. When A
, or a character sufficiently close to it is presented to the hologram, with the original illumination, the code-word B
will flash out. This means that the hologram can act as a ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | engrams. Fig. 1 shows how this is achieved.
中文
Fig. 1. Apparatus for producing a coding hologram and using it for the read-out.
中文
The light of a laser issues from a point L
, and a beam splitter consisting of a spherical mirror and a semi-reflecting mirror produces of this two images L′
and L′′
. The first o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In the making of the master hologram all engrams in one layer are marked, that is to say, exposed simultaneously, with one distinctive code-word, which is selected by a mask. But as each code-word illuminates the whole area of the hologram, a further mask must be used near the plane of the photographic plate, which cut... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | A method of reading the code-words is to sum up all the light which appears in one zone, corresponding to one position in the code, and guide it to a separate photoelectric detector. Each detector is fitted with a level discriminator, so as to reject spurious signals below a certain level. This method is simple; but it... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | code-word, which, however, is washed out by intermodulation with the character, and is useless for recognition. But the useful quarter is concentrated in extremely small solid angles. For example, if four or six identical engrams are spaced out by about 25mm, the solid angle in which the major part of the light corresp... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 激光器的发明在很大程度上推动了全息术的复苏,因为它使利用量级为10,000的干涉产生全息图成为可能,这样也可以充分利用细粒照相干板上的信息容量。
英文
我要说明的是,现在利用全息术有望解决计算机和其他数据处理装置中最为紧迫的问题之一——对具有多种变形字符的识别。
英文
波前重建包含了一个尚未被充分应用的原理。通常表现为:两束相干波同时照射在一张照相干板上,其中一束来自物体A
,另一束来自物体B
。如果全息图单独用A
照明,B
也会出现,反之亦然,全息图就是通过这样的方式将它们联系在一起的。至今,这个原理已经通过下述方式加以利用:若A
是被关注的物体,B
是光源(通常是简单的一个单个的光源),在重建中,全息图用... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
照相干板经M
·N
次连续曝光后,增至一个适合介质的光密度,再通过处理和洗印就制成了主全息图,总伽玛值最好为2,并将照片放回原始位置。在读取过程中使用了照明光的所有点源,而整个编码板是被遮盖住的。透镜3用于观测,它产生了一个编码板的实像。这时如果记录介质被拖过窗口,只要有字符或其变形在其中出现,其编码字便会立刻显现出来。在像平面放置一个掩模是有好处的,这个掩模是编码板的复制品,具有很细的孔,因此可以排除信号光外的所有光。这类掩模也能通过照相而制得。
英文
读取编码字的方法是:将与编码中某一位置相对应的一个带中出现的所有的光相加,并将它导入一个单独的光电探测器。每个探测器与一水平鉴别器相配,以排除低于一定水平的乱真信... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | chlorpromazine.
中文
S
INCE Friedhoff and van Winkle1
reported that they had isolated the compound 3,4-dimethoxyphenyl-ethylamine (DMPE)—the “pink spot”—from the urine of 15 out of 19 schizophrenics whereas they found it was absent in 14 mentally normal people, other workers have carried out similar investigations. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | : A survey of mentally normal individuals some of whom were apparently healthy in every way and some of whom were in-patients in the wards of two general hospitals.
中文
Exp. I.
The urines of 101 mental hospital in-patients, all “possible schizophrenics”, were tested with the primary object of finding the incidence o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The urine sample was, whenever possible, collected over 20h, though in some cases shorter periods of collection proved more practicable. The extraction and the paper chromatography were carried out as described by Friedhoff and van Winkle1
and this is referred to here as Method 1. Where there was marked interference b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | and did not interview the patients personally as did the psychiatrist in Exp. I. He divided the cases into four groups: (a
) “non-paranoid” schizophrenics; (b
) “paranoid” schizophrenics; (c
) schizophreniform syndromes (where although some features of schizophrenia were present it was uncertain whether or not the p... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The results of Exp. II are given in Table 4 and the statistical analysis in Table 5. The controls are 310 mentally normal individuals (tested by Method 2) one of whom had the pink spot. The results for the schizophrenform syndrome class have not been analysed because the group was probably very heterogeneous.
中文
Tab... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Table 6. Comparison of Method 1 and Method 2 in Investigation of the Pink Spot
中文
Though there is a significant correlation, P
= 1.06×10–10
, between the results given by the two methods, there are discrepancies.
中文
There are several reasons which might account for this non-concordance: (1) Method 2 may be les... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The second experiment using a different method for detecting the pink spot again shows the very strong association between the presence of the pink spot and “non-paranoid” schizophrenia. The lower frequency of the pink spot may be due to any of the four reasons mentioned above and/or to the cases being loss florid than... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ultra-violet absorption and it is difficult to obtain patients (particularly acute cases) who are not on drug therapy.
中文
We thank Dr. B. Finkleman, Prof. F. J. Fish, Dr. A. V. de P. Kelly, Dr. I. Leveson, and Dr. B. Ward for allowing us to examine and test their patients, and the staffs of the hospitals concerned f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
自从弗里德霍夫和范温克尔[1]
报道他们从19名精神分裂症患者中的15个人的尿液中分离出化合物3,4–二甲氧基苯基乙胺(DMPE)——“粉红色斑点”——而在14名精神正常的人中没有发现这一物质之后,其他工作者也开始进行类似的研究。其中,森和麦克吉尔[2]
、屈尔等人[3]
以及霍威特[4]
的研究证实了这一结果,而佩里等人[5]
以及福尔拜和平德[6]
的研究没有得到这种结果,武贞等人[7]
发现在他们近一半的对照样品中也存在该化合物。在这一系列实验中,被测个体的数目少,而且他们中没有一个是在忽视诊断的前提下进行检测的。过去,在精神分裂症患者中发现过很多代谢异常现象,但之后没有一种被证明与该病有根本上的关系。因... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 他把患者分为4组:(a
)“非妄想症”精神分裂症;(b
)“妄想症”精神分裂症;(c
)精神分裂症样综合征(尽管有一些精神分裂症的特征,但最初诊断不能确定是否是精神分裂症);(d
)非精神分裂征,包括躁狂抑郁症、器官性痴呆和心理缺陷。
英文
因为病例是由不同的精神病专家根据病历中的诊断结果进行评判的,所以这些分类可能没有实验I那样严格。
英文
纸层析过程也是按照弗里德霍夫和范温克尔[1]
所述的方法(我们称为“方法1”)进行的,但使用的萃取过程是不同的,是按照我们定义的方法2进行的。使用2摩尔/升的氢氧化钠溶液将过夜16小时的体积为300毫升~500毫升尿样的pH值调至9.0。然后用100毫升1,2–二氯乙烷萃... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 然而按照施奈德的方法,没有足够的证据显示施奈德阳性“非妄想症”组与粉红色斑点之间有明确关系,尽管数据强烈地倾向于这一方向。
英文
两个实验给出的证据表明粉红色斑点与精神分裂症高度相关,而在其他的精神障碍类型、近亲属或对照组中并不经常出现。此外,根据我们的调查,日常饮食和日常生活不大可能对粉红色斑点的产生起到非常重要的作用。异常代谢物是先于疾病产生还是由疾病引起,这是一个重要的问题。家族数据指向后者,但粉红色斑点可能只在精神障碍发生前短暂地显现,而且许多精细技术可以验证出近亲属中的斑点。密切注意处于康复期的粉红色斑点呈阳性的妄想症型精神分裂症患者将很有趣,因为这些数据可能暗示疾病的严重程度是否与粉红色斑点的数量有关。如果真是这样... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | A Morphogenetic Hormone
The juvenile hormone is a morphogenetic hormone—one of the most outstanding morphogenetic hormones known. The existence of a hormone responsible for maintaining larval characters was first revealed by the fact that decapitation in young Rhodnius
larvae causes premature metamorphosis1
. Parabio... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Experiments by many authors have shown that the juvenile hormone controls metamorphosis in insects of all kinds. In holometabolous insects, which have a pupal stage between the larva and the adult, the juvenile hormone again controls the morphogenetic change; a large amount of the hormone ensures retention or re-develo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . Indeed, there are a number of polymorphic changes in which there is evidence that the level of juvenile hormone activity may itself be involved, notably (i) the change over from the “solitary” to the “gregarious” form in locusts9
; (ii) the switch from apterous to alate forms among parthenogenesis aphids10
; (iii) ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In general it can be said that in most adult tissues it is not possible to induce any reversal of metamorphosis. But there are certain undoubted examples of such reversal: in the abdominal cuticle of Rhodnius
17
and of Oncopeltus
18
, in the thoracic cuticle of the earwig Auisolabis
, where the “ecdysial line” chara... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | within 24 h after moulting to the adult. This is a response to some hormonal factor in the newly moulted adult. But if the gland has been exposed to juvenile hormone during the pre-moulting period, it does not respond in this way and fails to undergo autolysis24
. (The breakdown of certain muscles after metamorphosis ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The precise nature of the gonadotrophic effect of the juvenile hormone is uncertain. The position is complicated by the fact that in some insects the secretion from the neuro-secretory cells in the brain seems to be more important than the juvenile hormone in ensuring yolk production. In the case of Rhodnius
, G. C. C... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | the juvenile hormone acts on the central nervous system and causes continuous activity. After allatectomy the insect continues to feed normally but it becomes inactive; consequently reserves pile up. The accumulation of reserves is not a feed-back effect from the gonads; the same effects are seen in males with or witho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ; the juvenile hormone seems specifically to induce the synthesis of yolk proteins in the fat body of Rhodnius
29
; as Gilbert38
has recently shown, the juvenile hormone will induce the fat body of the cockroach Leucophaea
to synthesize ovarian lipids. But these, and many similar effects, are elements in a pattern o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . It is particularly effective if its stability is increased by blocking the alcohol end of the molecule in the form of an ether (for example, farnesyl methyl ether) or as the farnesyl acetone41
.
中文
In the form of the methyl ether, a 0.06 percent solution of the active trans-trans
isomer is far more effective tha... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | as described here with half the earlier dose, that is, with about 2.5 μg of the active isomer of farnesyl methyl ether per gram of body-weight.) At the present time farnesol derivatives are the only compounds of known chemical composition with juvenile hormone activity. They were identified as the substance with juveni... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Ozeki, K., Sci. Papers Coll. Gen. Educ. Univ. Tokyo
, 11
, 102 (1961).
Piepho, H., Naturwiss.
, 27
, 301 (1939).
Piepho, H., and Meyer, H., Biol. Zbl.
, 70
, 252 (1951).
Gilbert, L. I., and Schneiderman, H. A., Trans. Amer. Micro. Soc.
, 79
, 38 (1960).
Wigglesworth, V. B., J. Insect Physiol.
, 9
, 105 (1963)... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
形态发生激素
保幼激素是一种形态发生激素——是已知最重要的形态发生激素之一。这种负责保持幼虫特性的激素的发现源于切除红猎蝽幼小的幼虫头部引起了过早的变态发育[1]
。异种共生实验显示这种激素在血液中自由循环;通过逐渐延长异种共生实验中昆虫头部前段的切除范围,发现这种激素不是来源于大脑,而是来源于咽侧体——外胚层的一种内分泌器官,位于口器的底部,正好在脑后[1]
。将幼小的幼虫(第三龄或第四龄)的咽侧体移植到第五龄的幼虫后,发现这些第五龄的幼虫并没有蜕变为成虫,而是成为巨型第六龄幼虫[2]
,此发现进一步证实了这个结论。
英文
保幼激素直接作用于负责在蜕皮阶段产生外皮的表皮细胞;限制激素的局部应用会使受限部分的幼虫... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 激素施用得太早,效率会降低——大概是因为在它起作用之前就在代谢过程中分解了[22,23]
。
英文
但是,早在激素效应出现之前,在细胞中就已诱导出一些效应。对刚喂完食的第五龄的红猎蝽幼虫施用很小剂量的保幼激素,不会对表皮类型产生影响:腹部产生了正常的成虫表皮。但是它确保毛原细胞(在变态过程中毛原细胞几乎会全部脱落,并从腹部的背面消失)全部继续存在,因此在成虫的腹部出现了多余的绒毛[23]
。
英文
保幼激素对于胸腺的继续存在也具有类似的作用。正常情况下,在红猎蝽蜕变为成虫后的24小时内胸腺(蜕皮激素的来源)自溶。这个过程是新蜕变的成虫中的某些激素因子作用的结果。但是如果在蜕变前这一时期,胸腺暴露在保幼激素中,就不会发... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
保幼激素的化学属性
保幼激素在惜古比天蚕蛾成虫中的大量积聚为含激素活性的提取物提供了来源。雄性飞蛾腹部的乙醚提取物是橙色油状物,富有保幼激素活性[28]
。这种物质可以用于发展化验方法[3,22]
,也可以用于发展通过逆流分离浓缩活性物质的方法[22]
。很多原始材料的提取物适用这些过程,并且显示出在动植物中广泛存在具有大致相同分离特性和保幼激素活性的材料:如在无脊椎动物和脊椎动物的组织中,在高等植物、部分细菌和部分酵母中。
英文
施麦阿来克对从其中两种原始材料(即拟步行虫幼虫的排泄物和酵母)提取出的物质进行了化学检验[39]
;分离出活性物质,结果显示是反–反–法呢醇及其乙醛法呢醛混合物。这就提出了一个问题,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 中文
T
esting a newly developed chemical reaction, we found the virus of hepatitis to consist of pure deoxyribonucleic acid without proteins, contrary to other known forms. This was investigated and confirmed as follows: by treatment with alcohol the virus can be precipitated like the nucleic acids and can be dissolved... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The hepatitis virus can be propagated on the chicken embryo by the following technique: (1) Treating the chorio-allantoic membrane with hyaluronidase just before inoculation; this loosens the tissue and thereafter the virus can passively permeate into the tissue; (2) the cytotoxic effect, especially from sera, can be r... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The virus was propagated from 144 cases of acute and chronic hepatitis epidemica, from serum hepatitis and from a series of normal blood donors. The virus was found in sewage as well as in blood and in faeces. All 144 virus stems tested were identical in electron micrographs and by immunological tests.
中文
For prepar... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | The hepatitis virus was more resistant to ultra-violet radiation. Irradiation of 0.5 ml. solutions in Petri dishes at a distance of 10 cm, using a mercury vapour lamp giving 2,540 Å emission, produced an area of inactivation of 8.5 cm diameter after 6 min.
中文
Since it was not possible to inoculate man with the virus... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
以下几个方面也表明肝炎病毒中的核酸是脱氧核糖核酸(DNA):(1)肝炎病毒能被DNA酶完全灭活,却不被RNA酶灭活;(2)在体内实验中,5–碘–2′–脱氧尿苷能抑制肝炎病毒的繁殖,然而影响RNA代谢的物质,如8–氮鸟嘌呤、2–硫尿嘧啶和5–氟尿嘧啶对其繁殖则没有影响;(3)在体内实验和体外实验中,放线菌素都能使肝炎病毒失活,而一般认为放线菌素在体外实验中抑制了DNA而不是RNA;(4)采用施密特和汤恩豪瑟[5]
的方法进行的推测证实了肝炎病毒是DNA型病毒。
英文
通过如下方法可以在鸡胚中成功繁殖肝炎病毒:(1)接种前用透明质酸酶处理绒毛尿囊膜,这样可以使组织松弛,之后病毒被动进入组织中;(2)通过稀释能够消除细胞毒... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
(彭丽霞 翻译;金侠 审稿)
Three Haemoglobins K: Woolwich, an Abnormal, Cameroon and Ibadan, Two Unusual Variants of Human Haemoglobin A
N. Allan et al.
Editor's Note
Here, biologist Hermann Lehmann from Cambridge University and colleagues, continue their catalogue of haemoglobin variants, describing and characterising thre... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | this haemoglobin K could be shown to be a β-chain variant. Unlike haemoglobin K Woolwich, the proportion of this haemoglobin K to haemoglobin S was 3 : 1, similar to that of haemoglobin A in the sickle-cell trait (A + S). There was no haemoglobinopathy. Indeed, the carrier of this K + S combination was found in the cou... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . Others may be considered as merely unusual, and they can be recognized by being found in equal proportion to haemoglobin A. The combination A + S (A > S) is an example of the first, abnormal type, and that for A + G Accra (A = G) represents the second unusual type. On two occasions a combination of unusual haemoglobi... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | TpVI that is usually present in peptide maps of haemoglobin A. An extended electrophoretogram (Fig. 5) showed these differences more clearly. βTpXIII represents residues 121-132 of the β-chain and βTpXIV residues 133-144.
中文
中文
Fig. 3. Peptide map of haemoglobin K Woolwich. Note that at 1 βA
TpXIII (positive for... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | are Lys→Gln, Lys→Asn, Lys→Thr and Lys→Met. The amino-acid analysis of the new peptide is given in Table 1. It will be seen that all the residues of βTpXIII and βTpXIV are present except for one lysine residue, and that one additional residue of glutamic acid was found. Glutamine is hydrolysed to glutamic acid when pept... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | electrophoretogram (Fig. 5). The increase in negative charge of βTpXIII is compatible with a haemoglobin K which differs from haemoglobin A by an additional negative charge per half-molecule. This, in βTpXIII, could only be the substitution of a neutral amino-acid residue by Glu or Asp. The absence of the incidental ch... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | TpV is missing at 1, and a new peptide can be seen at 2, with the electrophoretic mobility of βA
TpIII(3). The starred peptide is the incidental chymotryptic β131-132 from βA
TpXIII which is missing in Figs.3 and 4
中文
Fig. 7. Paper electrophoresis (90 min at p
H 6.4) of methionine containing peptides from haemog... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | TpV had the same electrophoretic mobility, whereas of the two negatively charged peptides, that from haemoglobin K had a greater mobility. If the amino-acid substitution Gly→Glu in haemoglobin K Ibadan had been at β56 no positively charged peptide would have resulted from the cleavage of the methionyl bond at β55. Both... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ) is abnormal. It is remarkable that the β132 lysine residue, which is substituted by one of glutamine in haemoglobin K Woolwich, is one of the most immutable residues in the evolution of haemoglobin. It is also found in myoglobin, and indeed no haemoglobin has as yet been described in which this β132 lysyl is not pres... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
以前曾经讨论过,当一些血红蛋白变体与血红蛋白A组合时,若血红蛋白变体占血红蛋白总量的一半以下时,即可被当作“异常”变体[4]
;但若它们与血红蛋白A含量相等,则只被认为是稀有变体。A+S(A>S)组合是第一种异常类型的例子。而A+G阿克拉(A=G)代表第二种稀有类型。还观察到以下两种情况是稀有血红蛋白与血红蛋白S的组合。血红蛋白S所占比例较少,就像在镰刀形红细胞性状携带者的血红蛋白A(A>S)组合中所发现的情况那样。血红蛋白J巴尔的摩[5]
和血红蛋白D伊巴丹[6]
是两种稀有血红蛋白,它们与血红蛋白S结合时构成总色素的大部分。在这两个例子中,含有组合血红蛋白的携带者没有镰刀形红细胞疾病,但他们是镰刀形红细胞性状的携带... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 可以看到通常靠近βTpVI的小点缺失了。已知这个小点代表二肽β131-132(Gln-Lys),它是胰蛋白酶消化时,胰凝乳蛋白酶附带裂解βTpXIII产生的。还可以注意到βTpXIII向正极有很小的偏移。延长的电泳图确认了βTpXIII电泳迁移率的这一变化(图5)。βTpXIII负电荷的增加与血红蛋白K一致,因为血红蛋白K与血红蛋白A的不同之处在于血红蛋白K每半个分子增加了一个负电荷。在βTpXIII中,这只可能是一个中性氨基酸残基被Glu或Asp(天冬氨酸)所取代。来自βTpXIII的附带的胰凝乳蛋白酶裂解肽缺失,提示β130酪氨酰肽键被附带胰凝乳蛋白酶裂解的作用受到抑制。这种抑制作用的产生,可能是因为β129的中性残基Ala(丙... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 这是第一次在人血红蛋白中观察到Gly→Glu的突变,虽然以前已经见到过Glu→Gly突变的发生[10]
。
英文
表3.血红蛋白A和血红蛋白K伊巴丹
用溴化氰裂解βTpV(β41~59)β55甲硫酰胺处得到的肽的氨基酸分析(摩尔比)
英文
这表明血红蛋白K喀麦隆(β130 Ala→Asp或Glu?)和血红蛋白K伊巴丹(α2
β2
46Glu
)是稀有血红蛋白,而血红蛋白K伍力奇(α2
β2
132Gln
)是异常血红蛋白。值得注意的是在血红蛋白K伍力奇中,被谷氨酰胺取代的β132赖氨酸残基是在血红蛋白演化过程中最稳定的残基之一。在肌红蛋白中也发现了这种情况,但在此之前却没有关于血红蛋白中不存在这个β132赖氨... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | the nucleus of which is a pentagonal dipyramid of seven spheres.
中文
Fig. 1. A layer of hard spheres based on a packing sequence of concentric pentagons.
中文
Following the foregoing packing sequence with polygons other than the pentagon results in other, well-known structures. The same sequence with squares yields... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | =1.0515. Thus this pentagonal structure has a density independent of position of 0.72357. This density is slightly lower than that for close packing (0.74048), but higher than body-centred cubic (0.68017) or icosahedral shell packing (0.68818) (ref. 2). The co-ordination is 10 at a distance of 1.000 and 2 at a distance... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | whiskers. On the other hand, it appears that the formation of a pentagonal dipyramid nucleus and its subsequent growth is a more probable and simpler mechanism for the formation of this structure. Furthermore, if a twinning mechanism were responsible for the five-fold symmetry one would expect [110] to be an observed w... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 根据几何学原理,晶体不能具有五重对称性:做五边形堆积而不产生空隙是不可能的。1984年人们发现一种金属合金具有明显的十重对称性,这一发现似乎是对上述观点的挑战,但是后来发现这个所谓的准晶体缺乏真正的晶体性质。巴格利的这篇文章发表于此前20年,文中他介绍了另外一种利用无限外延密堆积小球而构建出五重对称结构的方法。然而,这种堆积在三维空间中不具有周期性,但是却具有一个明确的中心。第二年,人们在病毒粒子中发现了一个巴格利方案的实例。巴格利还引用了德斯蒙德·贝尔纳提出的、存在于简单液体中的五重对称性团簇结构,而后来这被认为是初期准晶体的晶核。
英文
假定如此构建一个硬球的平面,使若干硬球形成许多同心五边形,且每个五边形边上的硬球数为奇... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
还应注意到,本文所述结构的五边形核与由贝尔纳[9,10]
提出的液体结构的重要组态之一具有相同的形式。从上述讨论中我们可以明显得出,这类组态在生长的过程中能够产生结晶。
英文
我要感谢弗兰克教授、史密斯教授和特恩布尔教授提供的意见,同时也感谢施乐公司提供的科研经费。这项研究的部分工作得到了海军研究办公室(合同为Nonr
1866(50))以及哈佛大学工程与应用物理学院的支持。
英文
(沈乃澂 翻译;赵见高 审稿)
Antimatter and Tree Rings
V. S. Venkatavaradan
Editor's Note
Physicists attempting to explain th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | increase of 1 percent in the year 1909, leading them to the conclusion that probably 1/7th of the energy release in the Tunguska meteorite impact came from antimatter annihilation.
中文
It is the purpose of this communication to point out that the probability of such an interesting conclusion is unfortunately very muc... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 然而在本文中,孟买塔塔基础研究所的印度物理学家文卡塔瓦拉丹指出,这种同位素比例的变化同样与太阳黑子的活动有关,因此上述证据不足以支持这个反物质的猜测。今天,科学家都认为通古斯事件是由于一块巨大的陨石撞击地球引起的。
英文
最近,考恩等人[1]
讨论了有趣的通古斯陨石撞击事件——他们主要根据撞击时释放出的极高能量(约1024
尔格)对该事件及其起因进行了讨论。讨论内容涉及关于事件起因的各种理论以及能量来源的性质(例如,小行星起源,能量来自于撞击还是核反应)。最后他们认为,没有一种理论能够圆满地解释撞击时所释放出的巨大能量。他们提出了反物质的假设,而且作为其假设的实验证据,他们还计算了陨石降落后大气中碳-14与碳-12比值增加... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | HEN I chose the present subject, I hoped that before I presented it the new report of the Interdepartmental Committee on Drug Addiction would have been published. However, it is still in the printer's hands, so I can say nothing about that now. When the report appears, however, as I hope it will soon, I believe it will... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Reviewing these facts, we made the following observations “To explain this trend in medication directed at the central nervous system, we have found no single answer. In part it must be due to the vigorous advertising of these drugs and their preparations by the pharmaceutical industry, both to the medical profession a... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | questions which should be considered not only by doctors, but by all concerned with social welfare.”
中文
These are certainly difficult questions, and I do not propose to try to answer them all now. What I shall try to do instead is to clarify them, to look at their implications, and to suggest ways in which we may ho... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | At least one valuable thing has emerged from the philosophy of the present century—its emphasis on the importance of words. So let us begin by asking what the word “drug” means, and why it means what it does. Webster's Dictionary
defines “drug” as “any substance used as a medicine, or in the composition of medicine, f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Drugs.
中文
This pejorative meaning of the word “drug” is relevant to this article, for the subject of drug-dependence is a highly emotional one. “Drug addiction” hits the headlines frequently in the Press, and is the subject of plays and broadcasts. As a social problem, it excites an interest out of all proportion to... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | This is no exaggeration. The drug addict in this narrower sense is indeed a pathetic figure and a potentially dangerous one, too, if he or she becomes a source of infection to others. But, as the World Health Organization Committee recognizes, these drug addicts, though creating special problems, are only part of the b... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Tobacco and alcohol may both be drugs of dependence. Their action is pharmacological, and in extreme cases the addict attempting to give them up suffers deprivation symptoms, which may be so severe that he is unable to do without them. The fact that they are both drugs which you prescribe and obtain for yourself, inste... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | with a patient of mine who once said: “Alcohol has been a very good friend to me”. This is a point to which I shall return.
中文
What are we to think of this steadily rising consumption of barbiturates and tranquillizers? Before we can answer this question, which is a very complex one, we need a great deal of informat... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | black market. In any event, I think it is clear that prescription figures are likely to be a very misleading guide to actual consumption.
中文
Nevertheless, let us assume—and experience shows that this is a reasonable assumption—that there are patients who are drug-dependent on barbiturates, not in the sense that they... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | depression by the antidepressant drugs. The authors of a recent monograph on the subject summarized the results of these forms of treatment as follows: “In general, these psychopharmacological agents have facilitated the control of mood and behavioural disturbances. In the mental hospital setting, they have induced a m... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | schizophrenia or depression purely in psychological terms, nor, for that matter, can we at present give a physiological explanation for them. It often appears easier to give a psychological explanation of the minor neurotic disorders from which many people suffer; but that does not exclude the probability that they, to... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | nerve cells and synapses, their groupings and interactions, their disorders and the effect of drugs on them. As a result, correlating in this way psychology, physiology, biochemistry and pharmacology, we shall have not only a more comprehensive armamentarium of drugs, but much more precision and individualization in th... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 本文是神经学家沃尔特·罗素·布雷恩在药学院的就职演说,他围绕药物依赖和滥用问题进行了讨论。他认为越来越多的含有镇静剂、兴奋剂和安定药的处方应当引起关注,但是其益处不能被忽视。拿安定药来讲,它确实可以让精神分裂症患者重新回归社会,减少对休克疗法的需求。他主张对药物处方和消耗模式进行一些研究,希望拿出一个可以影响未来药物设计的综合方案。同时,他补充道:“还有许多要说的是,我们的理想状态是在没有药物帮助的情况下,只是借助某种赋予生命一定意义的人生观,依靠身体自身与疾病作斗争。”
英文
在我选择这个题目时,我希望在我演讲之前药物成瘾跨部门委员会的新报告就已经公布了。但是现在仍然在印刷中,因此关于那份报告我现在不能说任何事情。在这份报告... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 因此让我们先看看“药物”这个词的含义,以及为什么它会有这种含义。《韦氏字典》对“药物”的定义是“作为药品或者药品成分的任何物质,内服或者外用”,接着它继续写道“一种特定的物质能否被包含在药物术语的范畴内取决于它售卖(与销售者有关)或者使用(与购买者有关)的目的”。因此有可能同一种物质有时候是药物而有时候不是。当我们开始使用其动词形式“给药”时,一个新的含义产生了,《韦氏字典》给出了三个定义:“(1)用药物或者其成分影响或者调节,尤其是用麻醉药麻醉;(2)用刺激性或者损伤性的东西使略受影响;(3)服用过量的或等量的药物”。因此一个不好的注解已经出现了:尽管我们说药物是药品的任何成分,但是普通人在听到某人被“给药”后不会认为他是服用了青... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 英文
我提到的烟草和酒精成瘾不仅因为它们固有的重要性(虽然是值得考虑的),也是为了提出更具有普遍意义的一点。世界卫生组织委员会指出,药物依赖的典型特征是继续服药的强烈欲望或需求。暂且不说慢性嗜酒者,即那些由于消耗大量的酒精而导致心理或身体上的副作用以至于需要医学治疗的人,还有许多习惯于饮用大于适量酒精的人声称因为饮酒他们感觉良好,如果因为某种原因他们无法获得酒精的话也会非常想念。他们会同意我的一位患者曾经说过的:“酒精已经是我的一个非常好的朋友。”这是我要说的一点。
英文
我们对巴比妥类药物和安定药消耗量的稳定增长怎么看呢?在回答这个非常复杂的问题之前,我们需要很多现在尚未获得的信息。正如第一届药物成瘾委员会在报告里说的:“... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 思维和躯体形成一个复杂的整体,当我们处理心理紊乱时,我们常常需要尽可能地把目前已知的心理和生理两方面的解释考虑进来。恰恰是由于我已经提到的这类原因,患者会不加选择地接受镇静剂的处方。但是还不能说他们持续服用这些药物是药物滥用。我再一次引用第一届药物成瘾委员会的报告:“当药物能够让他们过上更幸福更有益的生活时,不是我们来决定他们偶尔或者定期地服用这些药物是否合理”。如果你是把酒精当成朋友的人,你当然认同在适宜的病例中定期服用镇静剂。
英文
但是,在我看来,对这些药物可能的最佳用途的真正限制源自我们的无知。我想通过展望未来来结束这次演讲。我预知有一天我们能够比现在更加了解大脑和思维之间的关系。一方面我们会有能够对人格作出准确的心理... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | that the multiplication of virus RNA proceeds via a replicating form. This form is readily differentiated from the RNA which is present in the complete virus particles by its considerably slower rate of sedimentation in sucrose, lower buoyant density in caesium sulphate and resistance to degradation by ribonuclease. It... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | is a double-stranded molecule which has gaps between adjoining segments of the residual plus strands. It is questionable whether such a molecule would be stable to relatively high concentrations of ribonuclease, for example, 50 μg/ml.9
.
中文
A model for the replicating form which accounts for these experimental find... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | virus-induced RNA has the same base composition as RNA extracted from purified virus10,11
. Recycling of the individual fractions showed, however, that peak A
was not homogeneous but consisted of a spectrum of fractions which differed in their sedimentation coefficients (Fig. 2B
, C
, D
). In contrast, different f... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | We have also examined the structure of the ribonuclease-resistant RNA obtained by two successive centrifugations in sucrose gradients of virus-induced RNA which had been treated with 0.01 μg RNase/ml. This has a base composition which is in agreement with its being a duplex structure consisting of a plus and a minus st... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | cell RNA was added to each sample before centrifuging to serve as an internal marker Fig. 3. Sedimentation in sucrose gradients of RNA from purified 32
P-labelled FMD
virus. (A
), Total RNA; (B
), fraction 3 from first sedimentation recycled in second gradient; (C
), recycled fraction 5; (D
), recycled fraction 6... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | This cyclic replicating form is consistent with the evidence available at present. On ribonuclease treatment the side chain will be removed and the ring probably opened at the growing point to yield a complete double strand. The hypothesis also explains the presence of virus-like RNA in virus-infected cells that has lo... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 负链具有感染性的可能性极小,因此这一感染性应该来源于正链。在目前较为认可的复制模式中,耐核糖核酸酶的RNA中的正链并不是完整的病毒RNA链,而是一组RNA分子,其每个分子的长度都比病毒RNA的长度短。到目前为止,许多实验室积累的证据表明,完整的病毒RNA分子对于感染是必需的[7,8]
。其次,如图1b
所示的模型中的耐核糖核酸酶RNA是一个双链的分子,其邻接的正链片段之间都有缺口。这样的分子在较高浓度的核糖核酸酶下(比如50微克/毫升[9]
)能否保持稳定是值得怀疑的。
英文
要想解释这些实验结果,病毒RNA复制形式的模型应该包含一个类似于耐核糖核酸酶的RNA部分结构的完整双链。在检测感染了口蹄疫病毒的幼仓鼠肾细胞中RN... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | (A
)总RNA;(B
)第一次沉降后的第2组分进行二次沉降的结果;(C
)第4组分二次沉降的结果;(D
)第6组分二次沉降的结果。在4°C下,将RNA在斯宾诺超速离心机的SW
25转子上以每分钟20,000转离心16小时。以离心前加入未标记的幼仓鼠肾细胞RNA的样品作为内参。
图3. 纯化的32
P标记的口蹄疫病毒中的RNA进行蔗糖梯度沉降的情况。(A
)总RNA;(B
)第一次沉降后的第3组分进行二次沉降的结果;(C
)第5组分进行二次沉降的结果;(D
)第6组分进行二次沉降的结果。以离心前加入未标记的幼仓鼠肾细胞RNA的样品作为内参。
英文
图4.耐核糖核酸酶的RNA和病毒RNA在10–2
摩尔/... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | OR many years now, we have been working on the epidemiology of Down's syndrome (mongolism) in the State of Victoria, Australia, and have charted its occurrences during 1942-64. Peaks of incidence, of 2-year duration have been recorded at 5-7 year intervals from 1942 until 1957 and, as a result of this, a further peak o... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | incidences of mongols, per 100,000 live births, and those of infective hepatitis, per million of population, was 0.81, significant at the level of P
<0.01.
中文
Fig. 1. Annual incidence of Infective hepatitis in Melbourne, and of mongol births 9 months later for the period 1952 to 1964
中文
We would, in fact, postu... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | 我们之所以提出这一假说,不仅由于我们研究团队中的一员斯托勒发现先天愚型患儿的出生和产妇在受孕前感染肝炎可能在临床上有联系;而且流行病学的研究发现先天愚型的发病在时间和地点上具有明显的群发性,即每年城市发病高峰的病例都比农村发病高峰的病例多(接触率更高),在城市发病高峰一年后,农村才出现发病高峰(表明传染病从高接触率的城市地区慢慢传播到农村地区)。在最近的一项调查中,我们试图将1952年~1964年间墨尔本地区每年先天愚型的发病情况和每年呈报的传染性疾病的发病情况联系起来。1952年维多利亚州开始呈现传染性肝炎。在所有的传染性疾病中,只有传染性肝炎与先天愚型的发病情况具有一致性(图1),如图中所示,传染性肝炎的发病时间比先天愚型早9个... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | LLOW me to take you on a ride on the treacherous wings of analogy, starting with an excursion into genetics. Creativity is a concept notoriously difficult to define; and it is sometimes useful to approach a difficult subject by way of contrast. The opposite of the creative individual is the pedant, the slave of habit, ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | One line of escape from the maze is indicated by a phenomenon known to students of evolution by the ugly name of paedomorphism, a term coined by Garstang2
some forty years ago. The existence of the phenomenon is well established; but there is little mention of it in the text-books, perhaps because it runs against the ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | Let me give an example, which will make clearer what I am driving at. There is now strong evidence in favour of the theory, proposed by Garstang2
in 1922, that the chordates, and thus we, the vertebrates, descended from the larval state of some primitive echinoderm, perhaps rather like the sea-urchin or sea-cucumber. ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | apes and other mammals, is only found in the embryonic stage. The same applies to the angle between the uro-genital canal and the backbone, which accounts for the singularity of the human way of mating. Other embryonic—or, to use Bolk's5
term, foetalized—features are the absence of brow-ridges, scantness of body-hair,... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | It can be shown, I think, that these two types of progress—the emergence of biological novelties and the creation of mental novelties—are analogous processes on different levels of the developmental hierarchy. But to demonstrate the connexion we must proceed stepwise from lower to higher organisms. One of the fundament... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | . But that is all the individual needs in order to regain its normal adaptive balance in a static environment (assuming that the traumatizing disturbance was only a momentary one). Phylogenetic “self-repair”, on the other hand, implies changes in the genotype to restore the adaptive balance in a changing environment.
... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | , the inexhaustible variations of the archetype of death and resurrection, dark night and spiritual rebirth, all revolve around this basic paradigm—Joseph in the well, Jesus in the tomb, Buddha in the desert, Jonah in the belly of the whale.
中文
There is no sharp dividing line between self-repair and self-realization... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | In the history of art, this cyclic process is even more obvious: periods of cumulative progress within a given school and technique end inevitably in stagnation, mannerism or decadence, until the crisis is resolved by a revolutionary shift in sensibility, emphasis, style.
中文
Every revolution has a destructive and a ... | 400套付费套装书 |
C:\Users\yuan\Documents\400套付费套装书\04-100套\epub\0306. 《自然》百年科学经典(英汉对照版)(第四卷)(1946-1965).epub | .epub | 35,511,682 | 2025-09-26T19:07:57.651603 | ideation which normally operate in the twilight below the level of focal awareness. Such intervention of unconscious processes in the creative act is now generally, if sometimes reluctantly, accepted even by behaviourists with a strong positivist bias. Allow me, therefore, to take it for granted that in the period of i... | 400套付费套装书 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.