全文获取类型
收费全文 | 1262篇 |
免费 | 171篇 |
出版年
2021年 | 11篇 |
2018年 | 10篇 |
2016年 | 17篇 |
2015年 | 28篇 |
2014年 | 35篇 |
2013年 | 40篇 |
2012年 | 61篇 |
2011年 | 54篇 |
2010年 | 43篇 |
2009年 | 33篇 |
2008年 | 57篇 |
2007年 | 49篇 |
2006年 | 46篇 |
2005年 | 34篇 |
2004年 | 41篇 |
2003年 | 53篇 |
2002年 | 47篇 |
2001年 | 39篇 |
2000年 | 38篇 |
1999年 | 31篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 18篇 |
1992年 | 18篇 |
1991年 | 24篇 |
1990年 | 16篇 |
1989年 | 34篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 21篇 |
1985年 | 25篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 27篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 20篇 |
1978年 | 16篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1975年 | 14篇 |
1974年 | 21篇 |
1973年 | 12篇 |
1968年 | 7篇 |
1935年 | 8篇 |
1930年 | 7篇 |
1929年 | 11篇 |
排序方式: 共有1433条查询结果,搜索用时 15 毫秒
1.
2.
3.
Direct evidence is presented for a proline cycle using a cell-free experimental system which sequentially transfers 3H from [1-3H]glucose to NADP+ to Δ1-pyrroline-5-carboxylate and yields [3H]proline. The formation of [3H]proline depends on the presence of NADP, Δ1-pyrroline-5-carboxylate, and the enzymes glucose-6-phosphate dehydrogenase and Δ1-pyrroline-5-carboxylate reductase. The production of [3H]proline from unlabeled proline in the presence of mitochondria provides direct evidence for one complete turn of a proline cycle which transfers reducing equivalents produced by glucose oxidation in the pentose pathway into mitochondria. In this cycle, proline is oxidized to Δ1-pyrroline-5-carboxylate by mitochondrial proline oxidase. Δ1-pyrroline-5-carboxylate is released from mitochondria and is recycled back to proline by Δ1-pyrroline-5-carboxylate reductase with concomitant oxidation of NADPH. At the maximal rate observed, 60% of Δ1-pyrroline-5-carboxylate produced is recycled back to proline. This cycle provides a mechanism for transferring reducing equivalents from NADPH into mitochondria and is linked to glucose oxidation in the pentose pathway by NADPH turnover. 相似文献
4.
Curt Herbst 《Development genes and evolution》1906,22(4):473-497
Ohne Zusammenfassung 相似文献
5.
The application of porous graphitic carbon as adsorbing phase for direct separation of enantiomeric acids and amines using chiral ion-pair chromatography is described. The enantiomeric amines were separated as diastereomeric ion pairs with N-benzyloxycarbonylglycyl-L -proline, N-benzyloxycarbonylglycylglycyl-L -proline, or captopril as the chiral counterion. High enantioselectivities were obtained for amines having a hydrogen bonding function in the vicinity of the asymmetrical carbon atom. Quinine was the chiral counterion used to separate the enantiomeric acids. The strongly UV-absorbing quinine improved detection of solutes having low UV-absorbing properties, e.g., (R,S)-2-chloropropionic acid, by “indirect detection.” Retention and stereoselectivity of enanticmeric acids were regulated by the quinine concentration and by the addition of carboxylic acids as well as polar modifiers, e.g., methanol and 2-propanol, to the mobile phase. © 1992 Wiley-Liss, Inc. 相似文献
6.
Curt Koßwig 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1932,4(1):22-32
Ohne Zusammenfassung 相似文献
7.
Liver alcohol dehydrogenase 总被引:3,自引:0,他引:3
G Pettersson 《CRC critical reviews in biochemistry》1987,21(4):349-389
The article deals with the structure and function of liver alcohol dehydrogenase and reviews mainly literature published after 1979, i.e., summarizes progress made in the field since Klinman presented her review on alcohol dehydrogenases. The emphasis will be on high-resolution crystallographic data, results obtained with metal-substituted enzyme derivatives, and on the mechanism and pH dependence of the catalytic reaction. 相似文献
8.
Promoters and processing sites within the transforming region of bovine papillomavirus type 1. 总被引:15,自引:9,他引:6
The mRNAs present in bovine papillomavirus type 1 (BPV-1)-transformed C127 cells were studied by primer extension. The results show that two internal promoters are present in the E region of BPV-1 in addition to the previously identified promoter at coordinate 1 (H. Ahola, A. Stenlund, J. Moreno-López, and U. Pettersson, Nucleic Acids Res. 11:2639-2650, 1983). One, located at coordinate 31, generated a set of mRNAs with heterogeneous 5' ends, which may encode the major transforming protein of BPV-1, the E5 protein. The second promoter, which is located at coordinate 39, generates colinear mRNAs which encode either the E4 protein or a truncated form of the E2 protein. Unlike the cottontail rabbit papillomavirus (O. Danos, E. Georges, G. Orth, and M. Yaniv, J. Virol. 53:735-741, 1985), BPV-1 appears to lack a separate promoter for expression of the E7 protein. The major splice sites in the transforming region (E region) of the BPV-1 genome were also identified by nucleotide sequence analysis. 相似文献
9.
1. A simple model based on rapid-equilibrium assumptions is derived which relates the steady-state activity of the Calvin cycle for photosynthetic carbohydrate formation in C3 plants to the kinetic properties of a single cycle enzyme (fructose bisphosphatase) and of the phosphate translocator which accounts for the export of photosynthate from the chloroplast. Depending on the kinetic interplay of these two catalysts, the model system may exhibit a single or two distinct modes of steady-state operation, or may be unable to reach a steady state. 2. The predictions of the model are analysed with regard to the effect of external orthophosphate on the steady-state rate of photosynthesis in isolated chloroplasts under conditions of saturating light and CO2. Due to the possible existence of two distinct steady states, the model may account for the stimulatory as well as the inhibitory effects of external phosphate observed in experiments with intact chloroplasts. Stability arguments indicate, however, that only the steady-state case corresponding to phosphate inhibition of the rate of photosynthesis could be of physiological interest. 3. It is concluded that chloroplasts under physiological conditions most likely operate in a high-velocity steady state characterized by a negative Calvin cycle flux control coefficient for the phosphate translocator. This means that any factor enhancing the export capacity of the phosphate translocator can be anticipated to decrease the actual steady-state rate of photosynthate export due to a decreased steady-state rate of cyclic photosynthate production. 相似文献
10.