全文获取类型
收费全文 | 627483篇 |
免费 | 70182篇 |
国内免费 | 536篇 |
专业分类
698201篇 |
出版年
2016年 | 6228篇 |
2015年 | 9057篇 |
2014年 | 10400篇 |
2013年 | 15386篇 |
2012年 | 16832篇 |
2011年 | 17102篇 |
2010年 | 11400篇 |
2009年 | 10647篇 |
2008年 | 15400篇 |
2007年 | 15917篇 |
2006年 | 15215篇 |
2005年 | 14698篇 |
2004年 | 14577篇 |
2003年 | 13980篇 |
2002年 | 13790篇 |
2001年 | 27627篇 |
2000年 | 28154篇 |
1999年 | 22355篇 |
1998年 | 7767篇 |
1997年 | 8225篇 |
1996年 | 7767篇 |
1995年 | 7205篇 |
1994年 | 7103篇 |
1993年 | 7169篇 |
1992年 | 18403篇 |
1991年 | 17913篇 |
1990年 | 17422篇 |
1989年 | 17034篇 |
1988年 | 15937篇 |
1987年 | 15282篇 |
1986年 | 14341篇 |
1985年 | 14499篇 |
1984年 | 12029篇 |
1983年 | 10321篇 |
1982年 | 8204篇 |
1981年 | 7594篇 |
1980年 | 6999篇 |
1979年 | 11750篇 |
1978年 | 9368篇 |
1977年 | 8754篇 |
1976年 | 8219篇 |
1975年 | 9112篇 |
1974年 | 10108篇 |
1973年 | 9966篇 |
1972年 | 9113篇 |
1971年 | 8400篇 |
1970年 | 7406篇 |
1969年 | 7233篇 |
1968年 | 6638篇 |
1967年 | 5644篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
H. Ronald Pulliam 《Human ecology: an interdisciplinary journal》1982,10(3):353-363
Patterns of conflict and cooperation both within and between societies may be related to the degree of cultural similarity within and between the same societies. A simple model of social learning is used to predict patterns of conflict and cooperation in hypothetical societies that differ in the roles of relatives and nonrelatives in the enculturation of children. The model is illustrated by comparing its predictions to known differences in the patterns of conflict between males inpatrilocal and matrilocal societies. 相似文献
202.
203.
M J Ronis I Johansson K Hultenby J Lagercrantz H Glaumann M Ingelman-Sundberg 《European journal of biochemistry》1991,198(2):383-389
The regulation of CYP2E1 and 2B1 was studied by following mRNA levels, catalytic activities and the subcellular distribution of the apoproteins in rat liver 0, 6, 12, 24, 48 and 96 h after a single intragastric dose of acetone. No changes were observed in hepatic CYP2E1 mRNA levels at any time after acetone treatment, whereas rapid rises were observed in the microsomal amount of CYP2E1 protein and CYP2E1-catalyzed 4-nitrophenol hydroxylase and carbon-tetrachloride-initiated lipid-peroxidation activities. However, CYP2E1-dependent catalytic activities declined much faster than the immunodetectable CYP2E1 protein, suggesting that this cytochrome P-450 is inactivated prior to degradation. Similar results were seen in primary hepatocyte cultures. By contrast, concomitant changes in levels of CYP2B1 and CYP2B1-dependent O-depentylation of pentoxyresorufin were observed in the same microsomal preparations. Investigation of the degradative mechanism of both CYP2E1 and CYP2B1 by immunoquantitation of the proteins in lysosomes and by immunohistochemistry indicated their degradation via an autophagic-lysosomal pathway. The data suggest that CYP2E1 is acutely inactivated in the endoplasmic reticulum and that degradation of this isozyme occurs, at least in part, by the lysosomal route. By contrast, CYP2B1 is principally controlled at the level of synthesis. 相似文献
204.
205.
A Rauch R A Pfeiffer G Leipold H Singer M Tigges M Hofbeck 《American journal of human genetics》1999,64(2):659-666
206.
Ia I Serkiz A I Lipskaia L B Pinchuk V V Trishin Iu F Kataevski? G N Koval' 《Radiobiologiia》1991,31(5):629-634
Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy. 相似文献
207.
V Ia Gotlib I I Pelevina E F Konoplia A A Al'ferovich A A Konradov 《Radiobiologiia》1991,31(3):318-325
On the basis of their own data and the literature the authors have analyzed the mechanism of biological action of low-level radiation on cells. In studying the harmful effect of gamma-radiation (10-40 cGy) on HeLa cells it was shown that damages occurred in 12 postirradiation generations. Analysis of cell distribution within the colonies has demonstrated that the share of colonies with low cell content and the number of giant cell increase. These data indicate that low-level radiation causes reproductive cell death that can occur not immediately but in later generations. 相似文献
208.
209.
An adaptation of the Sols and Ponz method for the study of glucose intestinal absorption was developed by considering the special conditions of our line research. The glucose absorption was studied in proximal jejunum, distal ileum and distal colon in Wistar rat. The main adaptations in the method for successive absorptions with intestinal perfusions in vivo were the length of the intestinal segment and the change of the pumping system. The results are very similar to those obtained with the original method. 相似文献
210.