全文获取类型
收费全文 | 553086篇 |
免费 | 69444篇 |
国内免费 | 186篇 |
出版年
2016年 | 6061篇 |
2015年 | 8594篇 |
2014年 | 10306篇 |
2013年 | 14530篇 |
2012年 | 16207篇 |
2011年 | 16353篇 |
2010年 | 10758篇 |
2009年 | 10195篇 |
2008年 | 14582篇 |
2007年 | 15427篇 |
2006年 | 14383篇 |
2005年 | 14087篇 |
2004年 | 13924篇 |
2003年 | 13506篇 |
2002年 | 12994篇 |
2001年 | 23028篇 |
2000年 | 23393篇 |
1999年 | 18894篇 |
1998年 | 7022篇 |
1997年 | 7310篇 |
1996年 | 7123篇 |
1995年 | 6805篇 |
1994年 | 6807篇 |
1993年 | 6715篇 |
1992年 | 16477篇 |
1991年 | 16333篇 |
1990年 | 16018篇 |
1989年 | 15560篇 |
1988年 | 14571篇 |
1987年 | 14003篇 |
1986年 | 13090篇 |
1985年 | 13309篇 |
1984年 | 11282篇 |
1983年 | 9956篇 |
1982年 | 7783篇 |
1981年 | 7375篇 |
1980年 | 6946篇 |
1979年 | 11179篇 |
1978年 | 8740篇 |
1977年 | 8082篇 |
1976年 | 7679篇 |
1975年 | 8415篇 |
1974年 | 8759篇 |
1973年 | 8565篇 |
1972年 | 8057篇 |
1971年 | 7007篇 |
1970年 | 6187篇 |
1969年 | 5821篇 |
1968年 | 5320篇 |
1967年 | 4611篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
341.
Two forms of a carbon monoxide-binding cytochrome were found to exist in CaCl2-precipitated microsomal subfractions of human placental homogenates at term. These exhibited absorption maxima at wavelengths of 450 nm and 421–432 nm. Conversion of P-450 to the degradation product could be prevented by resuspension of the microsomes in buffered solutions containing 20% glycerol and 10?4M dithiothreitol. Solubilization of such resuspended microsomes with sodium cholate could be effected with minimal degradation. The solubilized pigment then could be partially purified by differential fractionation with ammonium sulfate. The partially purified cytochromes did not appear to bind desmethylimpramine but did bind aniline and nicotinamide to yield atypical type II difference spectra with maxima at 435 nm and minima at 416 nm. A type I difference spectrum could be elicited with androstenedione and a spectral dissociation constant (KS) of 4.7×10?8M was obtained. Androstenedione also appeared to effectively prevent the binding of carbon monoxide to the cytochrome. 相似文献
342.
343.
344.
The hippocampus and behavioral maturation 总被引:3,自引:0,他引:3
345.
346.
347.
348.
Sieve element pores in Nicotiana pith culture 总被引:3,自引:0,他引:3
349.
350.
The effects of mammalian gonadotropins, methyltestosterone and partially purified salmon gonadotropin on spermiation and oocyte maturation were studied in adult grey mullet. Methyltestosterone was a potent spermiating agent in both prespawning and spawning trials. The most effective dose was 5 mg/100 g body weight. Human chorionic gonadotropin (HCG) was moderately effective at a dose rate of 20 IU/100 g body weight. Both hormones blocked resorption of milt in captive animals. The HCG, FSH/LH combination, Synahorin+mullet pituitary homogenate, and partially purified salmon gonadotropin were equally effective, at the doses used, in inducing oocyte maturation and preventing onset of atrophy before completion of vitellogenesis. Atrophy occurred in all experimental fish at mean oocyte diameter of 750 μ. The significance of this finding is discussed. (Oceanic Institute Contribution No. 98). 相似文献