全文获取类型
收费全文 | 8282篇 |
免费 | 178篇 |
国内免费 | 322篇 |
专业分类
系统科学 | 204篇 |
丛书文集 | 202篇 |
教育与普及 | 105篇 |
理论与方法论 | 23篇 |
现状及发展 | 2011篇 |
研究方法 | 225篇 |
综合类 | 5994篇 |
自然研究 | 18篇 |
出版年
2022年 | 86篇 |
2021年 | 102篇 |
2020年 | 93篇 |
2018年 | 86篇 |
2017年 | 86篇 |
2016年 | 96篇 |
2015年 | 198篇 |
2014年 | 274篇 |
2013年 | 288篇 |
2012年 | 394篇 |
2011年 | 396篇 |
2010年 | 357篇 |
2009年 | 386篇 |
2008年 | 419篇 |
2007年 | 403篇 |
2006年 | 356篇 |
2005年 | 315篇 |
2004年 | 261篇 |
2003年 | 188篇 |
2002年 | 202篇 |
2001年 | 297篇 |
2000年 | 267篇 |
1999年 | 193篇 |
1992年 | 105篇 |
1991年 | 95篇 |
1990年 | 96篇 |
1989年 | 78篇 |
1988年 | 85篇 |
1987年 | 83篇 |
1986年 | 62篇 |
1985年 | 98篇 |
1984年 | 81篇 |
1983年 | 62篇 |
1982年 | 65篇 |
1981年 | 59篇 |
1980年 | 76篇 |
1979年 | 146篇 |
1978年 | 134篇 |
1977年 | 107篇 |
1976年 | 79篇 |
1975年 | 74篇 |
1974年 | 98篇 |
1973年 | 103篇 |
1972年 | 89篇 |
1971年 | 111篇 |
1970年 | 100篇 |
1969年 | 96篇 |
1968年 | 95篇 |
1967年 | 87篇 |
1966年 | 86篇 |
排序方式: 共有8782条查询结果,搜索用时 15 毫秒
951.
952.
It was found that cell-free extracts of Saccharomyces cerevisiae contain thiaminase II which hydrolyzes thiamine and thiamine analogs. The possible involvement of this enzyme and thiamine-synthesizing enzymes in thiamine production from thiamine antagonists is discussed. 相似文献
953.
Protein kinase C injection into hippocampal pyramidal cells elicits features of long term potentiation 总被引:9,自引:0,他引:9
G Y Hu O Hvalby S I Walaas K A Albert P Skjeflo P Andersen P Greengard 《Nature》1987,328(6129):426-429
Long-term potentiation (LTP) in the hippocampus is an interesting example of synaptic plasticity because of its induction by physiological discharge rates and its long duration. Of the possible biochemical mechanisms that regulate prolonged changes in cell function, protein phosphorylation is a particularly attractive candidate. We have therefore examined the effect of intracellular injection of calcium/diacylglycerol-dependent protein kinase (protein kinase C (PKC] in CA1 pyramidal neurones in hippocampal slices. Injection of the active enzyme elicited long-lasting enhancement of synaptic transmission, similar to LTP, whereas inactivated kinase failed to do so. The observed changes included an increased amplitude of the excitatory post-synaptic potential (e.p.s.p.) and an increased probability of firing and a reduced latency of the associated actin potential. 相似文献
954.
M Recasens Y Aoki P Mandel 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(15):1437-1439
Chloroiodoquine has been implied in numerous cases of myeloneuropathy in Japan, while in other countries although equally frequently used, only a few cases have been reported after treatment with this drug. Studies on the effect of chloroiodoquine in mice of various inbred strains or from crossings between sensitive and insensitive strains demonstrated a genetic predisposition of sensitivity to chloroiodoquine. 相似文献
955.
956.
957.
958.
959.
Summary Corticotropin1–24 and [Gly1]corticotropin1–18 amide increased the fluorescence of 1-anilinonaphthalene-8-sulfonate which bound to the bovine adrenocortical membranes. The two ACTH fragments interacted with the protein of the membranes and increased the net positive charge of the membranes.We thank Prof. Dr.M. Kikuno for his stimulating criticism. This work was partly supported by a grant from Keio University School of Medicine. 相似文献
960.
J Marchelidon E Fontaine-Bertrand R Salesse J Garnier E Burzawa-Gérard Y A Fontaine 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1978,287(4):301-304
Purified gonadotropin subunits of a teleost Fish, the Carp, reassociated in vitro, according to a second order rate reaction. The rate constant was temperature dependent. Compared to ovine LH, the Q10 was about three times less and the rate constant much greater (160 times for instance at 20 degrees C). The possible physiological significance of these differences is underlined. 相似文献