全文获取类型
收费全文 | 27631篇 |
免费 | 95篇 |
国内免费 | 112篇 |
专业分类
系统科学 | 123篇 |
丛书文集 | 451篇 |
教育与普及 | 36篇 |
理论与方法论 | 90篇 |
现状及发展 | 12120篇 |
研究方法 | 1262篇 |
综合类 | 13284篇 |
自然研究 | 472篇 |
出版年
2013年 | 214篇 |
2012年 | 425篇 |
2011年 | 894篇 |
2010年 | 172篇 |
2008年 | 489篇 |
2007年 | 598篇 |
2006年 | 532篇 |
2005年 | 568篇 |
2004年 | 616篇 |
2003年 | 498篇 |
2002年 | 531篇 |
2001年 | 860篇 |
2000年 | 825篇 |
1999年 | 589篇 |
1992年 | 556篇 |
1991年 | 386篇 |
1990年 | 422篇 |
1989年 | 406篇 |
1988年 | 404篇 |
1987年 | 415篇 |
1986年 | 455篇 |
1985年 | 581篇 |
1984年 | 403篇 |
1983年 | 333篇 |
1982年 | 294篇 |
1981年 | 319篇 |
1980年 | 372篇 |
1979年 | 871篇 |
1978年 | 681篇 |
1977年 | 655篇 |
1976年 | 523篇 |
1975年 | 516篇 |
1974年 | 776篇 |
1973年 | 639篇 |
1972年 | 706篇 |
1971年 | 765篇 |
1970年 | 1073篇 |
1969年 | 842篇 |
1968年 | 725篇 |
1967年 | 747篇 |
1966年 | 711篇 |
1965年 | 531篇 |
1964年 | 180篇 |
1959年 | 267篇 |
1958年 | 525篇 |
1957年 | 361篇 |
1956年 | 279篇 |
1955年 | 255篇 |
1954年 | 297篇 |
1948年 | 186篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
952.
LexA protein inhibits transcription of the E. coli uvrA gene in vitro 总被引:19,自引:0,他引:19
953.
954.
955.
Dorothy Chase W. C. Ullrick K. A. Dasse D. J. Burke A. H. Goldberg 《Cellular and molecular life sciences : CMLS》1981,37(12):1300-1301
Summary Results of unilateral achilles tenotomy on older (350–410 g) male rats, showed that the general width of Z-lines in the tenotomized muscles was not significantly altered by this procedure. Streaming of the Z-lines and rod formations was still present, as in younger rats.This investigation was supported in part by NIH grants 1-RO1-NS-14033 and 1-T32-07224. 相似文献
956.
A Sobel T Heidmann J P Changeux 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,285(14):1255-1258
A protein is purified by differential centrifugation from membrane fragments rich in acetylcholine receptor prepared from Torpedo marmorata electric organ after dissolution by a mixture of non denaturing detergents. After polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate and Coomassie blue staining the purified protein yields a single band of apparent molecular weight 43,000. Spectroscopic experiments carried out in the absence of Ca++ and detergents reveal that the 43 K protein interacts with the fluorescent local anesthetic quinacrine and with the frog toxin histrionicotoxin (apparent KD : 7 X 10(-7) M) but not with carbamylcholine and the alpha toxin from N. nigricollis. 相似文献
957.
A Friggi A M Chevalier-Cholat J Torresani 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(18):1835-1837
During intravenous infusion of propranolol (0.3--0.8 mg/kg) in the Rabbit, systolic arterial pressure is decreased (-6.5 +/- 4.2 mmHg) and electrical activity recorded from central end of the renal nerve is reduced significantly (-8.7 +/- 14.-%) with regard to the activity obtained, at the same pressure levels, by hemorrhage (+7.9 +/- 6.4%; p less than 0.25) or by intravenous infusion of the peripheral vasodilator sodium nitroprusside (+14.1 +/- 9.9%; p less than 0.01). 相似文献
958.
B. Csillik Elizabeth Knyihár A. A. Elshiekh 《Cellular and molecular life sciences : CMLS》1977,33(5):656-657
Summary Perineural colchicine- or vinblastine-treatment results in disappearance of non-lysosomal acid phosphatase activity, characterizing axon terminals in the Rolando substance of the normal spinal cord. Ultrastructural alterations are identical with those seen in the course of degenerative atrophy.Supported by research grant No. 4-01-0303-01-1 from the Hungarian Ministry of Health. 相似文献
959.
The structure of the combining site of the DNP binding IgA mouse myeloma protein MOPC 315 has been determined by a combination of high resolution nuclear magnetic resonance, electron spin resonance, model building and chemical modifications. This approach yields that general dimensions of the site, its polarity and asymmetry features, the assignment of the DNP-contact residues and their three-dimensional coordinates. 相似文献
960.
A Dautigny I Bernier J Jollès J Colombani P Jollès 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,285(16):1535-1536
Two serologically active urinary glycoproteins (HLA-A 9 and HLA-B 12) were isolated from urine provided by a patient suffering from tubular proteinuria. Their N-terminal sequences were automatically determined. The latter were identical with the sequence of another urinary glycoprotein (protein HC). The relationship between protein HC and the serological activity is discussed. 相似文献