全文获取类型
收费全文 | 780篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
802篇 |
出版年
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 2篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 39篇 |
2013年 | 45篇 |
2012年 | 36篇 |
2011年 | 36篇 |
2010年 | 35篇 |
2009年 | 29篇 |
2008年 | 33篇 |
2007年 | 57篇 |
2006年 | 39篇 |
2005年 | 35篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 1篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 25篇 |
1984年 | 40篇 |
1983年 | 34篇 |
1982年 | 46篇 |
1981年 | 44篇 |
1980年 | 34篇 |
1979年 | 26篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1972年 | 1篇 |
排序方式: 共有802条查询结果,搜索用时 3 毫秒
31.
The treatment of 6-phosphogluconate dehydrogenase from Candida utilis with dansyl chloride causes the modification of one amino acid residue per enzyme subunit and the inactivation of the enzyme. Either a cysteine or a tyrosine residue can be modified, depending on the pH of the reaction mixture. The dansyl residue can be transferred from one residue to the other suggesting that the two amino acid residues are close in the tridimensional structure of the active site of the enzyme. 相似文献
32.
33.
34.
Active transport of inorganic phosphate into whole cells of a strain (AB3311) derived from K12 was found to be partially resistant to 50 μM carbonyl cyanide -chlorophenyl hydrazone (CCCP), a powerful uncoupler of oxidative phosphorylation. The presence of 10 mM dithiothreitol (DTT) before the addition of CCCP completely prevented the inhibition of phosphate uptake caused by the uncoupler. The addition of DTT to the CCCP-inhibited system restored phosphate uptake to the control rate even when added 5 min after the phosphate transport assay was started. This uncoupler resistant transport is insensitive to anaerobiosis, or the addition of 10 mM KCN which reduces oxygen consumption to less than 1% that of aerobic controls. Additional studies of transport in a mutant (CBT302) deficient in membranebound Ca2+-, Mg2+-ATPase activity also demonstrated the retention of appreciable inorganic phosphate uptake under anaerobic conditions. 相似文献
35.
We report here a convenient and inexpensive method of attaching enzymes to solid supports which contain diols. Dextran coated porous glass, Sepharose and glass coated with a glyceryl silane were oxidized with NaIO4. Trypsin, carboxypeptidase A, and carboxypeptidase B were bound to the oxidized supports by treatment with NaBH4. The pH dependence of the coupling reaction and loss of lysine in bound trypsin indicate that the immobilization occurs via reductive alkylation. The bound enzymes display good catalytic activity against synthetic substrates and proteins. 相似文献
36.
37.
Abstract The effect of cadmium (Cd) on methane formation from methanol and/or H2 –CO2 by Methanosarcina barkeri was examined in a defined growth medium and in a simplified buffer system containing 50 mM Tes with or without 2 mM dithiothreitol (DTT). No inhibition of methanogenesis by high concentrations of cadmium was observed in growth medium. Similarly, little inhibition of methanogenesis by whole cells in the Tes buffer system was observed in the presence of 430 μM Cd or 370 μM mercury (Hg) with 2 mM DTT. When the concentration of DTT was reduced to 0.4 mM, almost complete inhibition of methanogenesis from H2 –CO2 and methanol by 600 μM Cd was observed. In the absence of DTT, 150 μM Cd inhibited methanogenesis from H2 –CO2 completely and from methanol by 97%. Methanogenesis from H2 –CO2 was more sensitive to Cd than that from methanol. 相似文献
38.
The model conjugates phycocyanin-allophycocyanin (C-PC-APC) and phycoerythrocyanin-phycocyanin-allophycocyanin (PEC-C-PC-APC)
were synthesized by using a heterobifunctional coupling reagent N-succinimidyl-3-(2-pyridyldithio)propionate. The rod-core
complex (αβ)6
PCLRC
27(αβ)3
APCLC
8.9 and phycobilisomes were separated from Anabaena variabilis. Energy transfer features for the conjugates and the complexes
were compared. The absorption and fluorescence emission spectra indicated that the linker-peptides mediate interaction of
phycobiliproteins and prompt energy transfer. The energy transfer in the conjugates was detected by fluorescence emission
spectra and confirmed by the addition of dithiothreitol. The conjugates may be used as models for studying the energy transfer
mechanism in phycobilisomes.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
39.
Thioredoxin h (TRX h) functions as a reducing protein and is present in all organisms. As a new approach for inducing the endoplasmic reticulum (ER) stress, TRX h (OsTRX23) was expressed as a secretory protein using the endosperm-specific glutelin GluB-1 promoter and a signal peptide. In transgenic rice seeds, the majority of the recombinant TRX h accumulated in the ER but some was also localized to the protein body IIs (PB-IIs). The rice grain quality was dependent on the TRX h accumulation level. Increased TRX h expression resulted in aberrant phenotypes, such as chalky and shriveled features, lower seed weight and lower seed protein content. Furthermore, the accumulation of some seed storage proteins (SSPs) was significantly suppressed and the morphology of the protein bodies (PB-Is and PB-IIs) changed according to the level of TRX h. SSPs, such as 13 kDa prolamin and GluA, were specifically modified via the reducing action of TRX h. These changes led to the activation of the ER stress response, which was accompanied by the expression of several chaperone proteins. Specifically, the ER stress markers BiP4 and BiP5 were significantly up-regulated by an increase in the level of TRX h. These results suggest that changes in the conformation of certain SSPs via the action of recombinant TRX h lead to an induced ER stress response in transgenic rice seeds. 相似文献
40.