全文获取类型
收费全文 | 7687篇 |
免费 | 78篇 |
国内免费 | 54篇 |
专业分类
系统科学 | 41篇 |
丛书文集 | 90篇 |
教育与普及 | 13篇 |
理论与方法论 | 17篇 |
现状及发展 | 3347篇 |
研究方法 | 410篇 |
综合类 | 3818篇 |
自然研究 | 83篇 |
出版年
2016年 | 48篇 |
2012年 | 106篇 |
2011年 | 206篇 |
2010年 | 56篇 |
2009年 | 53篇 |
2008年 | 153篇 |
2007年 | 177篇 |
2006年 | 134篇 |
2005年 | 139篇 |
2004年 | 240篇 |
2003年 | 125篇 |
2002年 | 132篇 |
2001年 | 296篇 |
2000年 | 293篇 |
1999年 | 214篇 |
1992年 | 118篇 |
1991年 | 123篇 |
1990年 | 106篇 |
1989年 | 99篇 |
1988年 | 106篇 |
1987年 | 120篇 |
1986年 | 114篇 |
1985年 | 158篇 |
1984年 | 121篇 |
1983年 | 98篇 |
1982年 | 84篇 |
1981年 | 116篇 |
1980年 | 109篇 |
1979年 | 251篇 |
1978年 | 198篇 |
1977年 | 183篇 |
1976年 | 137篇 |
1975年 | 158篇 |
1974年 | 209篇 |
1973年 | 173篇 |
1972年 | 193篇 |
1971年 | 212篇 |
1970年 | 273篇 |
1969年 | 209篇 |
1968年 | 188篇 |
1967年 | 210篇 |
1966年 | 181篇 |
1965年 | 144篇 |
1959年 | 53篇 |
1958年 | 104篇 |
1957年 | 76篇 |
1956年 | 73篇 |
1955年 | 52篇 |
1954年 | 74篇 |
1948年 | 49篇 |
排序方式: 共有7819条查询结果,搜索用时 15 毫秒
41.
Summary The binding of coumarin to serum proteins of the rat has been demonstrated. Of the total bound coumarin (37% of injected dose), 36% was bound to the slow and fast 1 globulins, 11% to the post albumins, 10% to globulin and 9% to albumin. 相似文献
42.
R. K. Raina D. Njoroge J. N. Ng'ang'a B. V. Telang 《Cellular and molecular life sciences : CMLS》1977,33(11):1499-1500
Summary
Naja mossambica pallida venom administered i.v. (300 /kg) produces an initial brief fall in blood pressure, due to a direct myocardial depressant effect, and a sustained fall due to central depressant effect.This study was supported by University of Nairobi research grants (670–376). We also thank Mr E. Njogu for photographic assistance. 相似文献
43.
I. J. Miller N. K. McCallum C. M. Kirk B. M. Peake 《Cellular and molecular life sciences : CMLS》1982,38(2):230-231
Summary The free radical oxidation of 1 and 6-tetrahydrocannabinol has been examined by spin trapping techniques and intermediates that would lead to cannabinol have been trapped. The 1st step in the oxidation of 1-THC involves the removal of 3-H, while for 6-THC, either 2-H or 5-H. Intermediates were isolated which could be pyrolysed to the diene and cannabinol. 相似文献
44.
Summary Leydig cell nuclear area and
5-3-hydroxysteroid dehydrogenase activity were increased in the testis ofBufo melanostictus 2 days after a single short-term cold exposure. Both parameters returned to normal values 4 days later. 相似文献
45.
C Radanyi G Redeuilh E Eigenmann M C Lebeau N Massol C Secco E E Baulieu H Richard-Foy 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1979,288(2):255-258
The antibodies against estrogen receptor were obtained after injecting Rabbits with a cytoplasmic receptor fraction isolated from Calf uterus. The estrogen receptor was partially proteolysed by the action of trypsin and subsequently purified by affinity chromatography (purification 4,000 to 10,000 fold, to a purity of 5-20%). The affinity of the antibody for the proteolysed receptor is KD approximately 1 nM and serum titres have reached values of approximately 50 nM. The values remained constant after the third injection. Preliminary results indicate that the antibody has approximately the same affinity for "native" cytoplasmic estrogen receptor from Calf uterus, as well as for the "trypsinized" forms of estrogen receptor isolated from Calf uterine cytosol and Hen oviduct nuclei. 相似文献
46.
S André N Farjaudon C Pareyre E Séguin 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1979,288(14):1095-1097
Comparing cytotoxicity of tubulosine and of six newly synthesized pseudo-tubulosines in the Allium test, we have characterized all the current features of protein inhibition. Nevertheless cytotoxicity of the six pseudotubulosines is much weaker. Furthermore, "floating poles anaphasis", a disturbance characteristic of the action of tubulosine, has been found with a lesser intensity with the other compounds. 相似文献
47.
Field stimulation of isolated, spirally-cut cervix from day-22 pregnant rats produced contractions which could be inhibited by tetrodotoxin or hyoscine and potentiated by propranolol. The rat cervix would appear to receive both cholinergic and noradrenergic innervations whose transmitters activate muscarinic cholinoceptors and beta-adrenoceptors respectively. 相似文献
48.
Suppressor cell induction can be demonstrated during antigen specific blastogenesis by using the same methods which have shown induction of suppressor cells by Con A. Since suppressor cells are rapidly generated during antigen specific blastogenesis, they must regulate the final level of blastogenesis induced during the seven day in vitro incubation. 相似文献
49.
Summary Viable cerebellar perikarya of mixed cell type obtained from 7–9-day-old rats were maintained in monolayer culture for up to 12 days. During this time extensive neurite formation and outgrowth occurred. The large majority of the cells developing in culture were tentatively identified as granule neurons. This identification was based on the large number isolated from the starting tissue, and the cells general morphological features in culture such as perikaryal and nuclear size, the bipolar nature of neurite extension, and their migratory behaviour.D.N. Currie was supported by a grant from Hoechst Pharmaceuticals, Ld, U.K.J.C. was supported by an S.R.C. Grant to S.P.R. RoseThe authors would like to thank Kathleen Tear for excellent technical assistance and members of the Brain Research Group for helpful discussions. 相似文献
50.
H. Goldman R. Fischer N. Nicolov S. Murphy 《Cellular and molecular life sciences : CMLS》1975,31(3):328-330
Zusammenfassung Die i.v. Verabreichung von LSD an Ratten steigert den Blutkreislauf im Hirnstamm sowie im frontalen und parietalen Cortex selektiv. Es wurden durch 6-Nor-LSD, 2-Methyl-LSD und
8, 9-LSD weder wahrnehmbare Verhaltensänderungen noch Änderungen des regionalen Blutkreislaufs verursacht. 相似文献