全文获取类型
收费全文 | 32284篇 |
免费 | 132篇 |
国内免费 | 297篇 |
专业分类
系统科学 | 431篇 |
丛书文集 | 538篇 |
教育与普及 | 130篇 |
理论与方法论 | 105篇 |
现状及发展 | 13042篇 |
研究方法 | 1178篇 |
综合类 | 16636篇 |
自然研究 | 653篇 |
出版年
2013年 | 353篇 |
2012年 | 615篇 |
2011年 | 1261篇 |
2010年 | 433篇 |
2009年 | 420篇 |
2008年 | 730篇 |
2007年 | 831篇 |
2006年 | 815篇 |
2005年 | 749篇 |
2004年 | 661篇 |
2003年 | 542篇 |
2002年 | 545篇 |
2001年 | 858篇 |
2000年 | 923篇 |
1999年 | 638篇 |
1994年 | 341篇 |
1992年 | 490篇 |
1991年 | 419篇 |
1990年 | 472篇 |
1989年 | 439篇 |
1988年 | 429篇 |
1987年 | 462篇 |
1986年 | 449篇 |
1985年 | 542篇 |
1984年 | 435篇 |
1983年 | 381篇 |
1982年 | 354篇 |
1981年 | 342篇 |
1980年 | 405篇 |
1979年 | 879篇 |
1978年 | 721篇 |
1977年 | 700篇 |
1976年 | 533篇 |
1975年 | 659篇 |
1974年 | 844篇 |
1973年 | 737篇 |
1972年 | 734篇 |
1971年 | 910篇 |
1970年 | 1027篇 |
1969年 | 886篇 |
1968年 | 881篇 |
1967年 | 848篇 |
1966年 | 755篇 |
1965年 | 551篇 |
1959年 | 304篇 |
1958年 | 524篇 |
1957年 | 407篇 |
1956年 | 321篇 |
1955年 | 335篇 |
1954年 | 313篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
H. Takeuchi T. Morimasa M. Matsumoto 《Cellular and molecular life sciences : CMLS》1977,33(7):938-939
Summary Several peptides were separated from-chymotrypsin-treated physalaemin by high voltage paper electrophoresis, and inhibition of the excitability of a molluscan giant neurone (tonically autoactive neurone) by the tripeptide, Lys-Phe-Tyr, was demonstrated.We thank Dr Sadaaki Iwanaga of Osaka University and Dr Atsuo Inoue of Daiichi Pharmaceutical CO for their helpful advice and the donation of the tripeptide (Lys-Phe-Tyr). 相似文献
113.
For the identification of a peptidyl principle inducing sexual agglutination in the yeast, 2 supposed hexapeptides (1a, b) were synthesized by the conventional method. The 1a (H-Arg-Gly-Pro-Phe-Pro-Ile-OH) revealed complete identity with the natural peptide in TLC, MS and biological property on agglutination. The 1b showed the sexual agglutinability in the same degree as 1a, though distinct differences were observed in the chemical data. Both 1a and 1b had a strong bitter taste. 相似文献
114.
In vivo studies indicated that the primary effects of E. coli endotoxin on hepatic clearance of sulfobromophthalein were at the excretory level. Newborns were more sensitive to the LPS than older animals. 相似文献
115.
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
116.
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
117.
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
118.
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
119.
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
120.
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