全文获取类型
收费全文 | 552篇 |
免费 | 26篇 |
专业分类
578篇 |
出版年
2022年 | 5篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 26篇 |
2012年 | 38篇 |
2011年 | 25篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 19篇 |
2006年 | 5篇 |
2005年 | 16篇 |
2004年 | 23篇 |
2003年 | 17篇 |
2002年 | 22篇 |
2001年 | 17篇 |
2000年 | 22篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 15篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 17篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1979年 | 11篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 10篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 8篇 |
1968年 | 3篇 |
排序方式: 共有578条查询结果,搜索用时 0 毫秒
571.
The sedimentation coefficient sN of the DNA topoisomer with the linking number N is evaluated as a function of N and chain length on the basis of a (circular) twisted wormlike chain, i.e., a special case of the helical wormlike chain. Evaluation is carried out by an application of the Oseen–Burgers procedure of hydrodynamics to the cylinder model with the preaveraged Oseen tensor. The necessary mean reciprocal distance between two contour points is obtained by a Monte Carlo method. It is shown that sN increases as |ΔN| is increased from 0 in the range of small |ΔN|, where ΔN = N ? N , with N the number of helix turns in the linear DNA chain in the undeformed state. It is found that there is semiquantitative agreement between the Monte Carlo values and the experimental data obtained by Wang for sN. 相似文献
572.
573.
Participation of cytochrome b5 in CMP-N-acetylneuraminic acid hydroxylation in mouse liver cytosol 总被引:1,自引:0,他引:1
The activity of CMP-N-acetylneuraminic acid hydroxylase, that converts CMP-N-acetylneuraminic acid (CMP-NeuAc) to CPM-N-glycolylneuraminic acid (CMP-NeuGc), in mouse liver was determined by a newly developed HPLC method using non-radioactive CMP-NeuAc as a substrate. The activity was detected in the cytosol fraction but not in the microsomal fraction. Either NADH or NADPH was used as an electron donor by the cytosol enzyme, but NADH was much more efficiently used than NADPH. An antibody against cytochrome b5 markedly reduced the CMP-NeuAc hydroxylase activity when added to incubation mixture containing either NADH or NADPH as an electron donor. These data led us to postulate the following electron transport system, which is involved in the CMP-NeuAc hydroxylation in mouse liver cytosol: (formula; see text) where X, Y, and Z are components supposedly involved. 相似文献
574.
575.
576.
577.
The authors made an immunocytochemical examination of the germinal centers (GCs) of (1) lymph follicles in physiological lymph nodes and (2) extra-nodal tissues of divergent diseases including thyroid disorders, rheumatoid arthritis, Warthin's tumor and Kimura's disease (Eosinophilic lymphfolliculoid granuloma). In these germinal centers, the presence of immunoglobulins (IgG and IgM), early acting complement components (C1q, C4, C3c, C3d), receptors for C3b and C3d and dendritic reticulum cell-1 was demonstrated in lace-like network patterns which were proven electron-microscopically to coincide with the surface of follicular dendritic cells. IgE was distributed in a lace-like pattern in the GCs of proliferating follicles of Kimura's disease, in which the lysis of follicles was frequently observed. This lysis appeared to be related to the presence of complement components. In the germinal centers of extra-nodal tissues, including the thyroid tissues accompanying the lymph follicles, rheumatoid arthritis synovial tissues as well as Warthin's tumors, thyroglobulin, rheumatoid factor and salivary amylase were detected as specific antigens, occurring in lace-like patterns. It is possible that follicular dendritic cells may play a role in the genesis of GCs and be responsible for the immune response through C3 receptors. 相似文献
578.