全文获取类型
收费全文 | 7808篇 |
免费 | 36篇 |
国内免费 | 24篇 |
专业分类
系统科学 | 57篇 |
丛书文集 | 18篇 |
教育与普及 | 4篇 |
理论与方法论 | 57篇 |
现状及发展 | 3864篇 |
研究方法 | 461篇 |
综合类 | 3320篇 |
自然研究 | 87篇 |
出版年
2018年 | 57篇 |
2017年 | 55篇 |
2016年 | 62篇 |
2014年 | 50篇 |
2013年 | 90篇 |
2012年 | 200篇 |
2011年 | 275篇 |
2010年 | 87篇 |
2008年 | 180篇 |
2007年 | 192篇 |
2006年 | 194篇 |
2005年 | 197篇 |
2004年 | 208篇 |
2003年 | 156篇 |
2002年 | 160篇 |
2001年 | 224篇 |
2000年 | 179篇 |
1999年 | 148篇 |
1992年 | 132篇 |
1991年 | 90篇 |
1990年 | 101篇 |
1989年 | 80篇 |
1988年 | 82篇 |
1987年 | 108篇 |
1986年 | 74篇 |
1985年 | 123篇 |
1984年 | 115篇 |
1983年 | 89篇 |
1982年 | 86篇 |
1981年 | 72篇 |
1980年 | 96篇 |
1979年 | 249篇 |
1978年 | 205篇 |
1977年 | 196篇 |
1976年 | 135篇 |
1975年 | 157篇 |
1974年 | 240篇 |
1973年 | 199篇 |
1972年 | 218篇 |
1971年 | 220篇 |
1970年 | 284篇 |
1969年 | 237篇 |
1968年 | 212篇 |
1967年 | 212篇 |
1966年 | 212篇 |
1965年 | 160篇 |
1964年 | 57篇 |
1958年 | 76篇 |
1957年 | 52篇 |
1954年 | 52篇 |
排序方式: 共有7868条查询结果,搜索用时 220 毫秒
891.
Summary Female rats fed 0, 25, 2500 and 10,000 IU vitamin E/kg diet for 3 months were examined for reproductive performance. On 10,000 IU vitamin E/kg diet, the fertility of inseminated rats was significantly reduced as compared to rats given normal or nutritional levels of vitamin E.This work was supported by research grants from the National Research Council of Canada and the Research Committee of The University of British Columbia. We thank Mrs Virginia Green for her help in statistical analysis. Reprint requests should be addressed to Dr I. D. Desai, Professor of Nutrition. 相似文献
892.
893.
In contrary to the wild strain, a monocaryotic mutant of Coprinus cinereus (basidiomycete) does not contain hydrosoluble, complex-bound sterols. Under nystatine-treatment, however, the mutant is induced to produce this kind of stereols in abundance. Furthermore, nystatine highly increases sporulation of the mutant and decreases sporulation of the wild strain. 相似文献
894.
A Guélin I E Michoustina S A Goulevskaya N V Petchnikov L A Ledova 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(21):2171-2174
Marine microvibrios, predators of E. coli, have been detected worldwide, from equatorial waters to the polar regions. The morphology and behavior of two microvibrios have been studied. Their multiplication and aggressiveness in regard to their bacterial prevy are not impeded by dialysis membranes and manifest themselves, away from all direct contact between the predator and its prey. 相似文献
895.
896.
Mechanosensitivity of mammalian auditory hair cells in vitro 总被引:1,自引:0,他引:1
Intracellular responses recorded in vitro from the cochleas of anaesthetized mammals have shown that the mechanoreceptive inner and outer hair cells are sharply tuned, accounting for many of the properties of the afferent fibres in the auditory nerve. However, in vivo it has not been possible to measure directly the excitatory mechanical input to these cells (the displacement of their mechanosensitive stereocilia) and thus to determine the relationship between the receptor potentials and displacement of their stereocilia. As a means of circumventing this technical difficulty, we have developed an organ culture of the mouse cochlea and here we describe the receptor potentials generated by the hair cells in response to direct displacement of their stereocilia. 相似文献
897.
T. V. Darnule V. Likhite A. T. Darnule G. M. Turino I. Mandl 《Cellular and molecular life sciences : CMLS》1980,36(5):606-607
Summary When guinea pigs instead of rabbits were used as the host animals, 8–16 times higher antibody titers against human lung elastin peptides were produced with only 1/20 the amount of antigen per unit body weight. This corresponds to a 200-fold enhancement of the immune response.Presented at the 6th Colloquium of the Federation of European Connective Tissue Clubs, Paris, August 28–30, 1978. The data form part of the Ph.D. thesis submitted by T.V. Darnule to the Department of Biology, New York University. Supported in part by NIH Program Project Grant HL15832 and by a Parker B. Francis Fellowship to T.V. Darnule. 相似文献
898.
Summary By repeated administration of tetrachloromethane, cirrhosis of the liver was evoked in dogs. In the course of the experiment one bitch had five litters, in all of which lesions of hepatic cells were found. In one group of animals, a diffuse steatosis of the liver was present; in the other group zonal necrosis was found. Malformations or fibrotic changes were not observed. 相似文献
899.
900.