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 31 毫秒
41.
K. Nielsen J. Sheppard W. Holmes I. Tizard 《Cellular and molecular life sciences : CMLS》1978,34(1):118-119
Summary Rats infected withTrypanosoma lewisi or decomplemented by injection of cobra venom factor or complement activating factor of trypanosomes were found to be more susceptible to infection withSalmonella typhimurium. Decomplemented rats subsequently infected withT. lewisi developed higher blood parasitemia than did normalT. lewisi infected rats.This project is supported by the National Research Council of Canada grant A 0068 and a grant from the International Development Research Center. 相似文献
42.
Summary A 2-dimensional thin-layer method has been developed for the separation on cellulose of adenine and guanine derivatives. Using incubated rat cerebral cortex slices it was shown that noradrenaline and acetylcholine stirnulated cAMP and cGMP production respectively but glutamate and -aminobutyric acid stimulated production of both cyclic nucleotides. 相似文献
43.
Summary The effects of selected -agonists and -antagonists on theophylline-induced lipolysis were investigate in isolated hamster white fat cells 2-Agonists (tramazoline, clonidine) inhibited theophylline-induced lipolysis while an 2-agonist (methoxamine) was without any effect. The inhibitory effect of 2-agonists was suppressed by yohimbine (2-antagonist), whereas 2-antagonists were inefficient. This result implies that the -adrenergic receptor of hamster fat cells is of the 2-type, although located postsynaptically.Acknowledgments. This work was supported by grants from CNRS (ERA 412) and DGRST (grant No. 787 1078). We thank M. Dauzats for excellent technical assistance. We thank Prof. H. Schmitt for tramazoline and AR-C 239 and for helpful discussion. 相似文献
44.
Summary
-adrenoceptor stimulation by isoprenaline increases the potassium efflux in beating guinea-pig atria. This effect is not mimicked by 8-bromo-cyclic AMP, a cyclic AMP analogue which exerts a positive inotropic effect in this preparation. 相似文献
45.
T. Stojanovié B. M. Djuričić B. B. Mršulja 《Cellular and molecular life sciences : CMLS》1980,36(12):1348-1350
Summary The activity of (Na++K+)-ATPase and acetylcholine esterase were folloed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na++K+)-ATPase was found in caudate. where the highest activity of acetylcholine esterase is found.These studies were supported by a grant from the Union of Science of Republic Serbia, No. 40404-14. 相似文献
46.
D. Sabourault Françoise Bauché Y. Giudicelli J. Nordmann R. Nordmann 《Cellular and molecular life sciences : CMLS》1981,37(3):227-229
Summary After 3 weeks of continuous ethanol intoxication by inhalation, the maximal number and affinity of the -and -receptors of rat heart were unchanged. These data indicate that adrenergic receptor disturbances are not involved in the mechanism of chronic ethanol-induced triglyceride deposition in the heart.Acknowledgments. This work was supported by grants from the Institut National de la Santé et de la Recherche Médicale. We wish to thank Mr M. Clément for skilled technical assistance in performing chronic ethanol inhalation treatments. 相似文献
47.
R. Lenzhofer C. Cerni I. Fröhlich J. Prager H. Pointner 《Cellular and molecular life sciences : CMLS》1981,37(9):1015-1017
Summary The influence of somatostatin on tumor cell growth was studied in vivo in mice (sarcoma 180 ascites tumor and Lewis lung tumor) and in vitro on nontransformed and polyoma-transformed cell lines. 4 or 20 g/100 g of cyclic somatostatin and 4 g/100 g of linear protamin Zn-bound somatostatin were injected s.c. twice daily in the in vivo study. Cyclic somatostatin (1, 4 or 10 g/ml) was added twice daily to the cell cultures. Somatostatin administration influenced neither the survival of animals nor the growth rate of cultured cell lines. *** DIRECT SUPPORT *** A2025117 00011 相似文献
48.
Summary Food ingestion of male guinea-pigs was restricted to 10 g/day. Total carnitine content of liver of the underfed animals fell to 3.75 moles per liver (46.1% of control). Serum level of total carnitine was 35.0 nmoles/ml (64.4%) in the underfed animals while they developed high ketonemia, 384.2 nmoles/ml (555.2%). In restricted animals the carnitine levels also decreased in the muscles. 相似文献
49.
50.
S. Bečka J. Bílek J. Slaba J. Škarda I. Mikuláš 《Cellular and molecular life sciences : CMLS》1977,33(6):771-772
Summary Goat placental lactogen was partially purified from a medium collected after placental tissue incubation. The data obtained by disc electrophoresis and isoelectric focusing experiments, as well as by means of radioreceptor assay methods, provide evidence of the similarity between the goat and ovine placental lactogen.The careful technical assistance of L. Tichovská is gratefuly acknowledged. 相似文献