全文获取类型
收费全文 | 24586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 | 12144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 | 426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 2 毫秒
151.
J. Kapitola H. Dlouhá Dr. J. Křeček J. Zicha 《Cellular and molecular life sciences : CMLS》1977,33(12):1615-1616
Summary Neurohypophyseal blood flow increases in water-deprived rats. This increase is independent of vasopressin release, since it occurs even in rats with hereditary defect of hypothalamic vasopressin synthesis.Acknowledgment. The technical assistance of D. Vilimovská is acknowledged. 相似文献
152.
H Meves Y Pichon 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(14):1325-1328
Most of the effects of 4-aminopyridine on the potassium conductance of the giant axon of the Squid can be explained in terms of a simple model based on the physicochemical properties of the molecule and what is known about the structure of the potassium "channels". 相似文献
153.
Summary The binding of coumarin to serum proteins of the rat has been demonstrated. Of the total bound coumarin (37% of injected dose), 36% was bound to the slow and fast 1 globulins, 11% to the post albumins, 10% to globulin and 9% to albumin. 相似文献
154.
A. R. Jones Carole Murcott D. H. Milton Jennifer Flynn 《Cellular and molecular life sciences : CMLS》1977,33(7):934-935
Summary The male antifertility agent 1-amino-3-chloropropan-2-ol (ACP,I) has been shown to be metabolized to-chlorohydrin (III) and metabolites of-chlorohydrin. This accounts for the similar antifertility and renal toxicity effects of both compounds. 相似文献
155.
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
156.
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
157.
Transposable genetic elements as agents of gene instability and chromosomal rearrangements. 总被引:31,自引:0,他引:31
Transposable genetic elements in prokaryotes and eukaryotes, when inserted at a given locus, can control expression of the locus and cause large scale rearrangements of adjacent DNA sequences. Striking similarities in genetic behaviour between the two groups of elements have led to the proposal of a molecular model of eukaryotic controlling elements, and to suggestions about the part such elements may play in evolution and differentiation. 相似文献
158.
Immune response (Ir) genes are linked to the species histocompatibility complex and define as yet uncharacterised phenotypic products which control the immune response to thymus dependent antigens. Antibody formation and antigen induced T lymphocyte proliferation are two examples of immune phenomena which, in vivo and in vitro, operate under Ir gene influence. To clarify their mechanism of action and cellular location, we have examined the contribution of antigen structure (amino acid sequence and conformation to Ir gene control of antigen recognition by T lymphocytes) as well as to the critical role played by the antigen presenting macrophage in expression of that control. We report that immune response gene control of antigen recognition operates at least in part at the level of the macrophage. 相似文献
159.
160.
Summary Daily evening injections of isoproterenol extended the period of high pineal N-acetyltransferase activity and retarded the growth of testes, seminal vesicles and prostate in rats treated neonatally with testosterone propionate.The authors are grateful to Mrs Marie Svobodová for her skillful technical assistance. 相似文献