全文获取类型
收费全文 | 390篇 |
免费 | 46篇 |
专业分类
436篇 |
出版年
2021年 | 5篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2016年 | 7篇 |
2015年 | 15篇 |
2014年 | 12篇 |
2013年 | 12篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 15篇 |
2009年 | 16篇 |
2008年 | 25篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 20篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有436条查询结果,搜索用时 0 毫秒
431.
Catechol oxidase was purified 330 × from chloroplasts of Clairette grapes. The MW of the enzyme is 80 000 and its Cu content is half an atom per molecule. The amino acid composition of the enzyme is also described. 相似文献
432.
433.
Primary human immunodeficiency virus (HIV) infection is characterized by an initial exponential increase of viral load in peripheral blood reaching a peak, followed by a rapid decline to the viral setpoint. Although the target-cell-limited model can account for part of the viral kinetics observed early in infection [Phillips, 1996. Reduction of HIV concentration during acute infection: independence from a specific immune response. Science 271 (5248), 497-499], it frequently predicts highly oscillatory kinetics after peak viremia, which is not typically observed in clinical data. Furthermore, the target-cell-limited model is unable to predict long-term viral kinetics, unless a delayed immune effect is assumed [Stafford et al., 2000. Modeling plasma virus concentration during primary HIV infection. J. Theor. Biol. 203 (3), 285-301]. We show here that extending the target-cell-limited model, by implementing a saturation term for HIV-infected cell loss dependent upon infected cell levels, is able to reproduce the diverse observed viral kinetic patterns without the assumption of a delayed immune response. Our results suggest that the immune response may have significant effect on the control of the virus during primary infection and may support experimental observations that an anti-HIV immune response is already functional during peak viremia. 相似文献
434.
435.
The conversion of 2-ketoglutarate-[14C] to 5-aminolevulinic acid-[14C] (ALA) by a cell-free system from maize leaves is described. Optimal conversion was achieved at pH 6.2 using a 20 000 g supernatant after gel filtration through Sephadex G-25. The formation of ALA required Mg2+, an amino donor (alanine or glutamate), pyridoxal phosphate and NADH. NADPH was somewhat less effective. 相似文献
436.
A gene (dexS) coding for a Streptococcus suis capsular type 2 dextranase (DexS) was detected in a recombinant gene library constructed in phage λZapII, and its nucleotide sequence was determined. Sequence comparison showed that the dexS gene product had significant similarities with enzymes which hydrolyze glucose polymers. Moreover, conserved amino acids that are suggested to be part of the active site of the glucosidases are also found in DexS. The dexS gene, adjacent to the gene encoding a S. suis IgG-binding protein, encoded a protein of approximately 62 kDa which exhibited DexS activity. 相似文献