全文获取类型
收费全文 | 24539篇 |
免费 | 60篇 |
国内免费 | 103篇 |
专业分类
系统科学 | 82篇 |
丛书文集 | 219篇 |
教育与普及 | 91篇 |
理论与方法论 | 71篇 |
现状及发展 | 10840篇 |
研究方法 | 984篇 |
综合类 | 12097篇 |
自然研究 | 318篇 |
出版年
2012年 | 303篇 |
2011年 | 604篇 |
2009年 | 144篇 |
2008年 | 382篇 |
2007年 | 440篇 |
2006年 | 406篇 |
2005年 | 436篇 |
2004年 | 475篇 |
2003年 | 431篇 |
2002年 | 424篇 |
2001年 | 766篇 |
2000年 | 775篇 |
1999年 | 536篇 |
1994年 | 326篇 |
1992年 | 460篇 |
1991年 | 379篇 |
1990年 | 442篇 |
1989年 | 397篇 |
1988年 | 396篇 |
1987年 | 424篇 |
1986年 | 428篇 |
1985年 | 526篇 |
1984年 | 390篇 |
1983年 | 372篇 |
1982年 | 314篇 |
1981年 | 314篇 |
1980年 | 366篇 |
1979年 | 758篇 |
1978年 | 642篇 |
1977年 | 566篇 |
1976年 | 475篇 |
1975年 | 531篇 |
1974年 | 648篇 |
1973年 | 562篇 |
1972年 | 599篇 |
1971年 | 768篇 |
1970年 | 853篇 |
1969年 | 714篇 |
1968年 | 733篇 |
1967年 | 631篇 |
1966年 | 594篇 |
1965年 | 427篇 |
1964年 | 158篇 |
1959年 | 233篇 |
1958年 | 427篇 |
1957年 | 320篇 |
1956年 | 250篇 |
1955年 | 246篇 |
1954年 | 245篇 |
1948年 | 218篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
J. Kędziora M. Soszyński G. Bartosz H. Witas W. Leyko 《Cellular and molecular life sciences : CMLS》1980,36(8):926-927
Summary A statistically significant decrease of prealbumin and statistically significant increases of alpha2-macroglobulin and IgA were found in blood plasma of patients with Down's syndrome using quantitative crossed immunoelectrophoresis.We are indebted to Prof. T.C. Bøg-Hansen, University of Copenhagen, for the helpful discussion of our results. 相似文献
172.
W. D. MacRae G. F. Q. Chan Chi-Kit Wat G. H. N. Towers J. Lam 《Cellular and molecular life sciences : CMLS》1980,36(9):1096-1097
Summary -Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither -terthienyl nor phenylheptatriyne induced chromosome aberrations.The authors wish to thank the National Science and Engineering Research Council for financial support of this research. 相似文献
173.
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
174.
D. V. Amin R. B. Doctor A. O. Girdhar U. H. Shah 《Cellular and molecular life sciences : CMLS》1980,36(12):1410-1411
Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms. 相似文献
175.
Summary The C-terminal amino acid sequences of human and of porcine antithrombin III have been determined as Gly-Arg-Val-Ala-Asn-Pro-Cys-Val-Lys and Gly-Arg-Val-Ala-Asn-Pro-Cys, respectively. These sequences are highly homologous with the C-terminal sequence of human -1-proteinase inhibitor. 相似文献
176.
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
177.
Summary Contrary to Srdi and Gloor's report, we find crystal cells (cc) in the lymph glands ofD. melanogaster larvae; the size and number of inclusions in the cc cannot be used to distinguish the 2 sibling species,D. melanogaster andD. simulans; cc in the hemocoel are not phagocytic cells; the surface properties of the lamellocytes are consistent with their derivation from plasmatocytes and not cc.Supported by grant No. CA16619 awarded by the National Cancer Institute, DHEW, USPHS. 相似文献
178.
H. Watanabe J. A. Menzies J. C. K. Loo 《Cellular and molecular life sciences : CMLS》1981,37(8):883-884
Summary Isonicotinic acid hydrazide (isoniazid) was shown to react readily with 17-ethinyl-17-hydroxyestr-4-en-3-one (norethindrone) to form the isonicotinyl hydrazone of the steroid under conditions likely to exist in the stomach. The hydrazone was detected in guinea-pig, but not rat, plasma following its oral administration. Rat liver tissue metabolized the compound more rapidly than guinea-pig liver in vitro which probably accounts for the failure to detect the hydrazone in rat plasma. 相似文献
179.
T. Kuroiwa S. Nishibayashi S. Kawano T. Suzuki 《Cellular and molecular life sciences : CMLS》1981,37(9):969-971
Summary DNA-containing areas in various phages (T4, , T7 and 29) could be observed at the light microscopic level using ethidium bromide epi-fluorescent microscopy. The fluorescent intensity per phage was in linear proportion to the DNA content in each phage.Acknowledgements. This work was supported in part by the grant No. 521708 and No. 511212 from the Japan Ministry of Education, Science and Culture. 相似文献
180.
Y. Kakiuchi G. M. Hughes T. Arai M. Horimoto Y. Kikuchi T. Koyama 《Cellular and molecular life sciences : CMLS》1981,37(4):376-377
Summary A needle type of colloid osmometer has been devised with special attachments which made it useable with 3-l samples. It has been used in oncometry of fresh water teleosts to give the following results: 5.1±1.0 mm Hg for goldfish, 5.2±0.71 mm Hg for carp, and 14.3±0.75 mm Hg for eel.This study was supported in part by Research Grant 387036 from the Ministry of Education of Japan.invited to National Institute of Physiological Sciences, Okazaki, Japan. 相似文献