全文获取类型
收费全文 | 7623篇 |
免费 | 636篇 |
国内免费 | 4篇 |
专业分类
系统科学 | 1120篇 |
丛书文集 | 2篇 |
理论与方法论 | 291篇 |
现状及发展 | 2236篇 |
研究方法 | 95篇 |
综合类 | 4438篇 |
自然研究 | 81篇 |
出版年
2018年 | 746篇 |
2017年 | 747篇 |
2016年 | 468篇 |
2015年 | 63篇 |
2014年 | 24篇 |
2013年 | 31篇 |
2012年 | 321篇 |
2011年 | 1053篇 |
2010年 | 849篇 |
2009年 | 473篇 |
2008年 | 563篇 |
2007年 | 812篇 |
2006年 | 65篇 |
2005年 | 116篇 |
2004年 | 179篇 |
2003年 | 216篇 |
2002年 | 108篇 |
2001年 | 42篇 |
2000年 | 33篇 |
1999年 | 26篇 |
1992年 | 21篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1985年 | 20篇 |
1984年 | 30篇 |
1983年 | 17篇 |
1982年 | 20篇 |
1981年 | 24篇 |
1980年 | 19篇 |
1979年 | 37篇 |
1978年 | 34篇 |
1977年 | 47篇 |
1976年 | 40篇 |
1975年 | 30篇 |
1974年 | 41篇 |
1973年 | 51篇 |
1972年 | 51篇 |
1971年 | 48篇 |
1970年 | 71篇 |
1969年 | 60篇 |
1968年 | 88篇 |
1967年 | 77篇 |
1966年 | 57篇 |
1965年 | 49篇 |
1964年 | 47篇 |
1963年 | 24篇 |
1962年 | 24篇 |
1961年 | 18篇 |
1959年 | 16篇 |
1957年 | 15篇 |
排序方式: 共有8263条查询结果,搜索用时 31 毫秒
991.
992.
A. Juhász-Nagy 《Cellular and molecular life sciences : CMLS》1973,29(5):563-565
Zusammenfassung Nachweis eines latenten reflektorischen Blutdruckabfalls bein Kaninchen in Pentobarbital-Narkose nach der Denervation des Karotis Sinus und des Aortenbogens. Die Reflexauslösung erfolgt durch Steigerung des venösen Drucks im Sinus coronarius. 相似文献
993.
994.
V. Jiráček I. Macháčková J. Koštíř 《Cellular and molecular life sciences : CMLS》1972,28(10):1164-1165
Summary Fifteen-day-old green pea seedlings were intoxicated 48 h by 1% gaseous sulphur dioxide and in their individual organs the activity of glutamate-oxalacetate (l-aspartate: 2-ketoglutarate-aminotransferase) and aspartate-pyruvate (l-alanine: oxalacetate-aminotransferase) transaminases estimated. The activity of glutamate-oxalacetate transaminase in the intoxicated seedlings was lowered in shoots by 77.8% and in roots by 78,9% as compared with the control plants. The activity of aspartate-pyruvate transaminase was lowered in shoots by 33.5%, in roots by 76% and in cotyledons by 54.5% in comparison with the control plants. 相似文献
995.
T. Várkonyi J. Polgár Ö. T. Zoltán B. Csillik M. Földi 《Cellular and molecular life sciences : CMLS》1970,26(1):67-68
Zusammenfassung Verschluss der zervikalen Lymphbahnen führt zu einer lymphostatischen, retinalen Hämangiopathie mit Verdickung und Strukturveränderung der Basalmembranen. 相似文献
996.
A dissociation between inhibition of RNA synthesis and cell lysis was observed when thymocytes of adrenalectomized rats were incubated with high concentrations of pregn-4-ene-11 beta-ol-3,20-dione and pregna-1,4-diene-11 beta-ol-3,20-dione. In contrast, no dissociation of these effects was found with the typical glucocorticoids cortisol and corticosterone, nor with their 1,4-diene analogs under the same conditions. 相似文献
997.
5-Azacytosine, 1-methyl-5-azacytosine and 5-azacytidine administered to rats with a ligated pylorus block gastric secretion, gastric acidity, the extent of hemorrhage and the number and size of gastric defects. The same drugs also depress the development of experimental acute pancreatitis mediated in rats by interstitial administration of 7.5% natrium cholate into the pancreas in vivo. The drugs affected the amount of abdominal fluid and 6 h after the treatment the pathological changes were significantly decreased. 相似文献
998.
A. Velázquez H. Andreu N. Xamena A. Creus R. Marcos 《Cellular and molecular life sciences : CMLS》1987,43(10):1122-1123
Summary Viability tests were performed on second and third chromosomes from lines ofDrosophila melanogaster selected for increased resistance to the organophosphorus insecticides dichlorvos and malathion, in order to evaluate the accumulation of drastic alleles. Our results show that malathion reduces significantly the relative viability of chromosome 3 and also increases the frequency of drastic alleles in this chromosome, while dichlorvos increases significnatly the frequency of drastic alleles in chromosome 2.Work supported in part by the Spanish Ministry of Education and Science (Grant No. 0577/84 CAICYT).—We are grateful to Productos Cruz Verde S.A. and Agrocrós S.A. for generously supplying the insecticides dichlorvos and malathion, respectively. 相似文献
999.
L. Selmeci E. Pósch Julia Mosonyi L. Hársing 《Cellular and molecular life sciences : CMLS》1981,37(1):24-25
Summary Unilateral ureteral obstruction in rats, resulted in considerable alterations of polyamine levels in the obstructed kidney during a 72-h observation period, as compared with respective values for the contralateral control kidney.This work was supported in part by the Ministry of Health, Hungary (1-04-0301-03-02/H). The skilful technical assistance of Ms G. Mayer and Mrs I. Harmos is highly appreciated. 相似文献
1000.