全文获取类型
收费全文 | 24593篇 |
免费 | 53篇 |
国内免费 | 70篇 |
专业分类
系统科学 | 173篇 |
丛书文集 | 205篇 |
教育与普及 | 72篇 |
理论与方法论 | 140篇 |
现状及发展 | 9872篇 |
研究方法 | 1114篇 |
综合类 | 12608篇 |
自然研究 | 532篇 |
出版年
2013年 | 178篇 |
2012年 | 396篇 |
2011年 | 946篇 |
2010年 | 165篇 |
2008年 | 469篇 |
2007年 | 480篇 |
2006年 | 493篇 |
2005年 | 508篇 |
2004年 | 546篇 |
2003年 | 466篇 |
2002年 | 442篇 |
2001年 | 681篇 |
2000年 | 683篇 |
1999年 | 473篇 |
1992年 | 434篇 |
1991年 | 325篇 |
1990年 | 355篇 |
1989年 | 361篇 |
1988年 | 367篇 |
1987年 | 380篇 |
1986年 | 343篇 |
1985年 | 490篇 |
1984年 | 374篇 |
1983年 | 277篇 |
1982年 | 258篇 |
1981年 | 253篇 |
1980年 | 295篇 |
1979年 | 696篇 |
1978年 | 524篇 |
1977年 | 515篇 |
1976年 | 478篇 |
1975年 | 516篇 |
1974年 | 638篇 |
1973年 | 591篇 |
1972年 | 566篇 |
1971年 | 716篇 |
1970年 | 956篇 |
1969年 | 742篇 |
1968年 | 720篇 |
1967年 | 703篇 |
1966年 | 688篇 |
1965年 | 474篇 |
1964年 | 175篇 |
1959年 | 266篇 |
1958年 | 480篇 |
1957年 | 301篇 |
1956年 | 292篇 |
1955年 | 237篇 |
1954年 | 257篇 |
1948年 | 242篇 |
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
171.
M. D. Adams J. T. Earnhardt B. R. Martin L. S. Harris W. L. Dewey R. K. Razdan 《Cellular and molecular life sciences : CMLS》1977,33(9):1204-1205
Summary Abnormal-8-tetrahydrocannabidiol (ABN-8-THC) failed to elicit central nervous system and cardiovascular effects in laboratory animals. Abnormal-cannabidiol (ABN-CBD) was also devoid of overt behavioral effects but produced marked hypotension with only slight bradycardia in anesthesized dogs.Acknowledgment. This work was supported by NIDA (grant No. DA-00574-01 and DA-00490) and Virginia Heart Society (grant No. RR-05697) 相似文献
172.
H. -J. Hess J. S. Bindra J. W. Constantine W. Elger O. Loge E. Schillinger W. Losert 《Cellular and molecular life sciences : CMLS》1977,33(8):1076-1077
Summary N-methanesulfonyl 16-phenoxy--tetranor PGE2 is a prostaglandin analog which is markedly more tissue selective than PGE2. This compound is 10–30 times more potent than PGE2 in animal models which are considered relevant to antifertility effects in humans. In pharmacological tests which are believed to be predictive for side effects in humans, the compound has potency either equal to or less than that of PGE2. 相似文献
173.
174.
175.
176.
177.
G. D. Ledney H. M. Gelston Jr S. R. Weinberg E. D. Exum 《Cellular and molecular life sciences : CMLS》1982,38(10):1228-1230
Summary Wound trauma-induced survival from radiation may be related to increased mitosis in hematopoietic cells. This is supported by the cell cycle-dependent drug hydroxyurea, which 1. blocked survival of wounded mice injected 2 or 3 days after 900 rad and 2. reduced the number of endogenous CFU-s in wounded mice injected shortly before 700 rad.Supported by the Armed Forces Radiobiology Research Institute, Defense Nuclear Agency, under Research Work Unit MJ00018. Views presented in this paper are those of the authors; no endorsement by the Defense Nuclear Agency has been given or should be inferred.Research was conducted according to the principles enunciated in the Guide for the Care and Use of Laboratory Animals prepared by the Institute of Laboratory Research, National Research Council. 相似文献
178.
G. Zamboni E. Perez P. L. Parmeggiani 《Cellular and molecular life sciences : CMLS》1982,38(10):1188-1189
Summary In rats adapted to a 1212 h light-dark (LD) schedule, cyclic AMP concentration in the preoptic region showed a L minimum and D maximum. No significant fluctuations were observed in the parietal cortex.Supported by grant No. 79.01946.04 awarded by the National Research Council (CNR), Rome, Italy. 相似文献
179.
Captopril (SQ 14,225): In vitro and in vivo influence on the proliferative response of rat lymphocytes 总被引:1,自引:0,他引:1
Lise Binderup E. Bramm E. Arrigoni-Martelli 《Cellular and molecular life sciences : CMLS》1982,38(3):399-401
Summary Captopril in vitro (50–500 g/ml) increased3H-TdR incorporation in unstimulated and mitogen-stimulated cultures of rat lymphocytes. Unseparated spleen and lymph node cells of rats orally treated with captopril (50 mg/kg/day×4) showed decreased basal and mitogen stimulated3H-TdR incorporation. The removal of macrophages abrogated this inhibitory effect. Leucine aminopeptidase activity of macrophages was reduced — in vivo and in vitro — by captopril.Acknowledgments. The authors thank the Squibb Institute for Medical Research for the gift of Captopril. The excellent technical assistance of Ms B. Hasselriis, Ms B. Rumler and Ms E. Greve Petersen is gratefully acknowledged. 相似文献
180.
Summary The defense secretion of soldiers ofReticulitermes lucifugus has been shown to contain, predominantly, (R)-(–)-(E,E)-geranyllinalool together with germacrene A and -farnesene.This report covers part of a collaborative study with J.-L. Clément, Lab. d'Evolution, Université P. et M. Curie, Paris, to whom we are grateful for supplies of material and discussions. We also thank Dr O.T. Jones for collections ofReticulitermes lucifugus. 相似文献