全文获取类型
收费全文 | 7410篇 |
免费 | 534篇 |
国内免费 | 1篇 |
出版年
2021年 | 86篇 |
2020年 | 42篇 |
2019年 | 85篇 |
2018年 | 112篇 |
2017年 | 83篇 |
2016年 | 123篇 |
2015年 | 200篇 |
2014年 | 270篇 |
2013年 | 400篇 |
2012年 | 425篇 |
2011年 | 436篇 |
2010年 | 273篇 |
2009年 | 235篇 |
2008年 | 414篇 |
2007年 | 406篇 |
2006年 | 403篇 |
2005年 | 400篇 |
2004年 | 401篇 |
2003年 | 422篇 |
2002年 | 360篇 |
2001年 | 187篇 |
2000年 | 238篇 |
1999年 | 190篇 |
1998年 | 115篇 |
1997年 | 93篇 |
1996年 | 89篇 |
1995年 | 96篇 |
1994年 | 74篇 |
1993年 | 54篇 |
1992年 | 126篇 |
1991年 | 108篇 |
1990年 | 109篇 |
1989年 | 95篇 |
1988年 | 77篇 |
1987年 | 63篇 |
1986年 | 68篇 |
1985年 | 48篇 |
1984年 | 68篇 |
1983年 | 48篇 |
1982年 | 30篇 |
1981年 | 23篇 |
1980年 | 36篇 |
1979年 | 35篇 |
1978年 | 29篇 |
1977年 | 28篇 |
1976年 | 24篇 |
1975年 | 23篇 |
1974年 | 28篇 |
1973年 | 27篇 |
1972年 | 22篇 |
排序方式: 共有7945条查询结果,搜索用时 265 毫秒
91.
92.
Takashi Yamaguchi Katsuzo Wakabayashi Toshio Mitsui 《Biochimica et Biophysica Acta (BBA)/General Subjects》1974,372(2):450-463
X-ray diffraction studies have been made on the cross-sectional structure of the normal Salmonella flagella. Two approaches have been made: one based upon small-angle equatorial scatterings (2θ 3°) and the other upon moderate-angle angle equatorial diffractions (3° 2θ 10°).Analysis of small-angle scattering data gives the radius of gyration of the flagella as 68 Å. Cylindrically averaged electron density of the cross-section of the flagella is obtained by means of the Fourier-Bessel transformation method. The average radius of the flagella is about 65 Å.In the investigation of the moderate-angle diffraction pattern, validity is examined of the model that a flagellum consits annularly arranged strands, of which each has a cylindrically symmetric structure. Features of the pattern observed in the range of 3° < 2θ < 10° can be interpreted fairly well by this model. Average radii of the flagella obtained for the 11 and 13 strands models are close to that obtained by the analysis of the small-angle scattering data. 相似文献
93.
94.
95.
96.
Yasuhiro Noguchi Ineko Tawara Kaio Kondo Hideo Nigi Toshio Tanaka 《Primates; journal of primatology》1969,10(3-4):273-283
The electrocardiograms of 157 healthy Japanese monkeys (Macaca fuscata), covering a wide range of ages in both sexes, were recorded under light pentobarbital (Nembutal) anesthesia. Although results were generally similar to those reported for other macaque species, some quantitative differences were observed.The heart rate was about 160 per minute in all monkeys examined; the P-Q interval was 0.11±0.06 sec.; the duration of QRS was 0.04±0.01 sec.; the Q-T interval was 0.24±0.06 sec. The mean axis of QRS was +59° and the pattern of the QRS complex was qR type in most cases.The comparison with the human electrocardiogram shows that the heart rate ofM. fuscata is about twice that of man, while the P-Q, QRS, and Q-T intervals were about one-half of those found in human subjects. In the monkey, however, the P wave was sharp and the T wave flat.In order to estimate the effect of anesthesia on the electrocardiogram, the records of several monkeys before, during, and after intravenous administration of barbiturates were compared. Although some animals showed extrasystoles after barbiturate was administered, generally no essential changes were noted in the records, except for the retardation of the rate and proportional prolongation of intervals.This work was presented at the 10th Annual Meeting of the Primate Research Association held in Inuyama, March 13, 1966. 相似文献
97.
Masashi Yamaguchi Theodore Yanos Tomoko Yamaguchi Abel Lajtha 《Developmental neurobiology》1969,1(4):419-433
When rat sciatic nerves were incubated with C14l-lysine, l- or d-glutamate, or d-l γ-aminoisobutyrate, the labeled compounds penetrated the nerve, and the level of lysine and leucine after 1 hr was higher in the nerve than in the medium. The level increased with time, and at 24 hr glutamate levels also were higher in the nerve than in the medium. Lowering the temperature strongly inhibited uptake, while other conditions such as absence of glucose, absence of sodium, or the presence of cyanide inhibited uptake by nerve less than uptake by brain slices. The uptake against a concentration gradient, and inhibitions of this uptake by metabolic inhibitors and by structural analogs, were interpreted as showing the presence of transport processes for amino acids in peripheral nerves with characteristics similar to such transport processes in the central nervous system. 相似文献
98.
99.