全文获取类型
收费全文 | 1044篇 |
免费 | 74篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 32篇 |
2020年 | 18篇 |
2019年 | 8篇 |
2018年 | 25篇 |
2017年 | 14篇 |
2016年 | 28篇 |
2015年 | 42篇 |
2014年 | 48篇 |
2013年 | 63篇 |
2012年 | 87篇 |
2011年 | 74篇 |
2010年 | 49篇 |
2009年 | 35篇 |
2008年 | 60篇 |
2007年 | 42篇 |
2006年 | 36篇 |
2005年 | 40篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 18篇 |
2001年 | 32篇 |
2000年 | 16篇 |
1999年 | 17篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 4篇 |
1973年 | 13篇 |
1972年 | 11篇 |
1971年 | 9篇 |
1970年 | 6篇 |
1966年 | 3篇 |
排序方式: 共有1118条查询结果,搜索用时 15 毫秒
861.
Ponnulakshmi Rajagopal Selvaraj Jayaraman Shazia Fathima JH Saravanan Radhakrishnan Patil Ashlesh Laxman Vijaya Prakash Krishnan Muthaiah Satyendra Chandra Tripathi TS Gugapriya Aaditya Madhusudan Tarnekar Gayatri Girish Muthiyan Vishwajit Ravindra Deshmukh Bharat Ramrao Sontakke Kirubhanand Chandrashekar 《Bioinformation》2021,17(11):928
862.
863.
864.
C L Hoppel D Grinblatt H C Kwok P K Arora M P Singh L M Sayre D Greenblatt 《Biochemical and biophysical research communications》1987,148(2):684-693
In order to clarify the structural requirements associated with the inhibition of mitochondrial respiration by MPP+, the neurotoxic metabolites of the Parkinsonian agent MPTP, ten sets of pyridine/N-methylpyridinium pairs and a few miscellaneous compounds were evaluated on rat liver intact mitochondria (Mw) and on submitochondrial particles (SMP). The pyridinium partners were much more potent inhibitors on Mw than on SMP, indicating that they are concentrated inside mitochondria by the energy-dependent process previously reported for MPP+, probably as a consequence of non-specific passive transport across the mitochondrial inner membrane in response to the transmembrane potential. In the SMP assay, the neutral pyridines were stronger inhibitors than were the pyridinium cations, and the inhibitory potency varied little with structural changes. The N-methylated forms of beta-carbolines may act as endogenous MPP+-like agents. 相似文献
865.
Anthrax toxin lethal factor contains a zinc metalloprotease consensus sequence which is required for lethal toxin activity 总被引:17,自引:2,他引:15
Comparison of the anthrax toxin lethal factor (LF) amino acid sequence with sequences in the Swiss protein database revealed short regions of similarity with the consensus zinc-binding site, HEXXH, that is characteristic of metalloproteases. Several protease inhibitors, including bestatin and captopril, prevented intoxication of macrophages by lethal toxin. LF was fully inactivated by site-directed mutagenesis that substituted Ala for either of the residues (H-686 and H-690) implicated in zinc binding. Similarly, LF was inactivated by substitution of Cys for E-687, which is thought to be an essential part of the catalytic site. In contrast, replacement of E-720 and E-721 with Ala had no effect on LF activity. LF bound 65Zn both in solution and on protein blots. The 65Zn binding was reduced for several of the LF mutants. These data suggest that anthrax toxin LF is a zinc metallopeptidase, the catalytic function of which is responsible for the lethal activity observed in cultured cells and in animals. 相似文献
866.
Structure and assembly of beta-barrel membrane proteins. 总被引:5,自引:0,他引:5
867.
The microsecond motions of spin-labeled lipids associated with the Na(+)/K(+)-transporting ATP hydrolase (Na,K-ATPase) in native and tryptically shaved membranes from Squalus acanthias have been studied by progressive saturation electron spin resonance (ESR). This includes both the segmental mobility of the lipid chains and the exchange dynamics of the lipids interacting directly with the protein. The lipids at the protein interface display a temperature-dependent chain mobility on the submicrosecond time scale. Exchange of these lipids with those in the bulk bilayer regions of the membrane takes place on the time scale of the nitroxide spin-lattice relaxation, i.e., in the microsecond regime. The off-rates for exchange directly reflect the specificity of ionized fatty acids relative to protonated fatty acids for interaction with the Na,K-ATPase. These essential features of the lipid dynamics at the intramembranous protein surface, namely, a temperature-dependent exchange on the microsecond time scale that reflects the lipid selectivity, are preserved on removing the extramembranous parts of the Na,K-ATPase by extensive trypsinization. 相似文献
868.
Liposomes are non-toxic, biodegradable and feebly immunogenic lipid vesicles made from natural and synthetic lipids. They are known to act as immunopotentiating agents and can be used to formulate sustained release preparation by encapsulation. In the present study, liposome entrapped allergen and free allergen were used to inject in Balb/C mice at different time intervals and their immune response in terms of specific IgG and specific IgE levels was quantitated by ELISA (Enzyme Linked Immuno sorbent Assay). The results indicated that specific IgE response was significantly higher in mice injected free allergen as compared to that of mice given liposome entrapped allergen. However, the specific IgG response was not statistically significant. Experiments carried out with liposome entrapped allergen and liposome coupled allergen showed no statistically significant difference in specific IgE and specific IgG titre between the two groups of mice. This type of immunomodulatory effect of liposomes in reducing IgE levels and without affecting IgG levels may be useful in Type I allergic disorders. 相似文献
869.
Biodiesel production using heterogeneous catalysts 总被引:3,自引:0,他引:3
The production and use of biodiesel has seen a quantum jump in the recent past due to benefits associated with its ability to mitigate greenhouse gas (GHG). There are large number of commercial plants producing biodiesel by transesterification of vegetable oils and fats based on base catalyzed (caustic) homogeneous transesterification of oils. However, homogeneous process needs steps of glycerol separation, washings, very stringent and extremely low limits of Na, K, glycerides and moisture limits in biodiesel. Heterogeneous catalyzed production of biodiesel has emerged as a preferred route as it is environmentally benign needs no water washing and product separation is much easier. The present report is review of the progress made in development of heterogeneous catalysts suitable for biodiesel production. This review shall help in selection of suitable catalysts and the optimum conditions for biodiesel production. 相似文献
870.