全文获取类型
收费全文 | 26866篇 |
免费 | 80篇 |
国内免费 | 112篇 |
专业分类
系统科学 | 139篇 |
丛书文集 | 140篇 |
教育与普及 | 74篇 |
理论与方法论 | 113篇 |
现状及发展 | 11194篇 |
研究方法 | 1169篇 |
综合类 | 13771篇 |
自然研究 | 458篇 |
出版年
2013年 | 204篇 |
2012年 | 398篇 |
2011年 | 858篇 |
2010年 | 171篇 |
2008年 | 476篇 |
2007年 | 543篇 |
2006年 | 541篇 |
2005年 | 557篇 |
2004年 | 562篇 |
2003年 | 521篇 |
2002年 | 482篇 |
2001年 | 868篇 |
2000年 | 866篇 |
1999年 | 538篇 |
1994年 | 354篇 |
1992年 | 530篇 |
1991年 | 393篇 |
1990年 | 461篇 |
1989年 | 422篇 |
1988年 | 392篇 |
1987年 | 457篇 |
1986年 | 444篇 |
1985年 | 583篇 |
1984年 | 427篇 |
1983年 | 373篇 |
1982年 | 334篇 |
1981年 | 320篇 |
1980年 | 337篇 |
1979年 | 862篇 |
1978年 | 645篇 |
1977年 | 595篇 |
1976年 | 538篇 |
1975年 | 560篇 |
1974年 | 695篇 |
1973年 | 622篇 |
1972年 | 566篇 |
1971年 | 708篇 |
1970年 | 981篇 |
1969年 | 716篇 |
1968年 | 719篇 |
1967年 | 690篇 |
1966年 | 697篇 |
1965年 | 488篇 |
1959年 | 245篇 |
1958年 | 433篇 |
1957年 | 259篇 |
1956年 | 264篇 |
1955年 | 231篇 |
1954年 | 214篇 |
1948年 | 241篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
261.
K. R. Middleton F. W. Schaefer H. J. Saz 《Cellular and molecular life sciences : CMLS》1979,35(2):243-244
Summary 4-Isothiocyanato-4-nitrodiphenylamine possessed anthelmintic activity againstNippostrongylus dubius andHymenolepis nana in mice andH. diminuta in rats as determined by both egg counts and recovery of parasites at autopsy. No activity was detected against the cestode,Spirometra mansonoides, in cats.This investigation was supported in part by grants AI-10512 and AI-09483 from the National Institutes of Health. The authors are indebted to Dr P.P. Weinstein for providing animals infected withSpirometra mansonoides. 相似文献
262.
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
263.
A. Borowska S. Sierakowski J. Maćkowiak K. Wiśniewski 《Cellular and molecular life sciences : CMLS》1979,35(10):1368-1370
Summary A correlation between the postirradiation increase of the small intestine motility and the prostaglandin-like activity in this organ during gastrointestinal syndrome was observed. Indomethacin decreased the elevated motility of intestine and reduced the prostaglandin-like activity in this syndrome.Acknowledgments. The work was supported by the Polish Academy of Sciences. 相似文献
264.
Summary Physostigmine in a dose of 0.1 mg/kg i.v. expressly stimulated the oxygen uptake in the rat cerebral cortex. This effect was blocked by propranolol and seems be mediated by catecholamines. Since atropine also antagonized the stimulant effect of physostigmine, it appears that the action of physostigmine is primarily cholinergic and that the adrenergic effect is a secondary phenomenon. The higher dose of physostigmine (0.4 mg/kg i.v.) caused a depression of rat brain oxygen uptake.This work was supported by a grant from Serbian Republic Scientific Fund (ZMNU SR Srbija), Belgrade (Yugoslavia).The authors wish to acknowledge the skilful technical assistance of Lj. Krsti. 相似文献
265.
A. Matsuo H. Nozaki H. Kataoka M. Nakayama S. Hayashi 《Cellular and molecular life sciences : CMLS》1979,35(10):1279-1280
Summary A new enantiomeric sesquiterpene alcohol named (–)-maalian-5-ol was isolated from the liverwort, and the structure and absolute configuration was determined to be the stereostructureI by chemical and spectral evidence.The authors express their gratitude to Dr H. Inoue, National Science Museum, for identification of the liverwort, and Prof. T. Tokoroyama, Osaka City University, for sending of the data of (–)--maaliene and (+)-selina-5,11-diene. Thanks are also due to the Ministry of Education for financial support of this work. 相似文献
266.
267.
B. Goldberg A. Stern J. Peisach W. E. Blumberg 《Cellular and molecular life sciences : CMLS》1979,35(4):488-489
Summary The low temperature EPR spectrum of a quickly reacted mixture of oxyhemoglobin and phenylhydrazine was studied. With the use of a computer, the spectral contribution of methemoglobin in the region of g=2 was subtracted. The remaining spectrum was that of an axial free radical (g=2.00, g=2.06) having the magnetic parameters of superoxide anion. In the presence of superoxide dismutase, this axial radical was not seen, confirming that superoxide anion is indeed generated by the reaction.The portion of this investigation carried out at the Albert Einstein College of Medicine was supported in part by US Public Health Service Research Grant HL-93399 from the Heart and Lung Institute and by National Institute Contract Nol-CP-55606 to J.P. This is communication No. 378 from the Joan and Lester Avnet Institute of Molecular Biology.Predoctoral fellow in the Medical Scientist Training Program (United States Public Health Service Grant 5-TO-5-GM 01669-12) at the New York University School of Medicine.Recipient of a grant-in-aid from the New York Heart Association. 相似文献
268.
P. J. Müller P. Masner Maria Kälin W. S. Bowers 《Cellular and molecular life sciences : CMLS》1979,35(5):704-705
Summary Corpora allata fromOncopeltus fasciatus incubated in vitro in medium containing 10–5.35 M (1 g/ml) of precocene II lose their ability to secrete juvenile hormone when reimplanted into last instar larvae.Acknowledgments. We thank Mr K. Dorn, Mrs L. Dolezal, Mrs V. Nötzli-Graf, Mr K.H. Trautmann and Mr A. Schuler for technical help, Dr W. Vogel and Dr A. Dübendorfer for valuable discussions. 相似文献
269.
High-frequency generalised transduction by bacteriophage T4 总被引:30,自引:0,他引:30
270.