全文获取类型
收费全文 | 15824篇 |
免费 | 922篇 |
国内免费 | 7篇 |
出版年
2023年 | 94篇 |
2022年 | 81篇 |
2021年 | 204篇 |
2020年 | 147篇 |
2019年 | 178篇 |
2018年 | 451篇 |
2017年 | 390篇 |
2016年 | 519篇 |
2015年 | 514篇 |
2014年 | 633篇 |
2013年 | 978篇 |
2012年 | 1261篇 |
2011年 | 1348篇 |
2010年 | 844篇 |
2009年 | 493篇 |
2008年 | 861篇 |
2007年 | 828篇 |
2006年 | 722篇 |
2005年 | 631篇 |
2004年 | 544篇 |
2003年 | 525篇 |
2002年 | 431篇 |
2001年 | 211篇 |
2000年 | 320篇 |
1999年 | 270篇 |
1998年 | 200篇 |
1997年 | 121篇 |
1996年 | 116篇 |
1995年 | 133篇 |
1994年 | 125篇 |
1993年 | 102篇 |
1992年 | 121篇 |
1991年 | 109篇 |
1990年 | 79篇 |
1989年 | 100篇 |
1988年 | 82篇 |
1987年 | 111篇 |
1986年 | 73篇 |
1985年 | 118篇 |
1984年 | 106篇 |
1983年 | 91篇 |
1982年 | 101篇 |
1981年 | 96篇 |
1980年 | 100篇 |
1979年 | 96篇 |
1978年 | 74篇 |
1977年 | 97篇 |
1976年 | 72篇 |
1975年 | 75篇 |
1974年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
101.
Glucose inhibits the inducible synthesis of β-D-glucosidase inStreptomyces granaticolor. Neither cAMP nor cGMP influence the inhibitory effect of glucose. Glucose also inhibits the inducible synthesis of the cellobiose
uptake system but has no effect on its activity. This may be the mechanism underlying glucose inhibition of induction of β-D-glucosidase inS.granaticolor. 相似文献
102.
103.
The regional distribution of L-homocysteine (Hcy) was determined in brains from mouse, rat, guinea pig, and rabbit, using a sensitive radioenzymatic assay. Large interspecies variations in the Hcy content in various parts of the brain were observed, but cerebellum contained the highest amount in all species investigated. In the rat the amount of Hcy in cerebellum (6.4 nmol/g) was about sixfold higher than in most other parts of the brain, whereas in the mouse and guinea pig the amount in cerebellum (about 1 nmol/g) was only twofold higher than in the other brain regions. There was a remarkably high level of Hcy in all regions of the rabbit brain (4-10 nmol/g); the highest concentration was found in the cerebellar white matter. In this species the amount of Hcy in all brain regions examined exceeded that in the liver. 相似文献
104.
105.
106.
107.
Jan Kopecký Josef Houštěk Eva Szarska Zdeněk Drahota 《Journal of bioenergetics and biomembranes》1986,18(6):507-519
The proteolipid subunit of H+-ATPase was labeled by [14C]N,N-dicyclohexylcarbodiimide in bovine heart mitochondria. The radioactive labeling was followed using various systems of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). When using discontinuous SDS-PAGE (Laemmli, U.K., 1970,Nature (London)227, 680–685) a monomeric (Mr 7600±1500) and a dimeric form (Mr 17,800±1200) of the proteolipid were detected, while only the monomeric form was found on urea (8 M) containing gels (SDS-PAGE according to Laemmli; or Swank, R. T., and Munkers, K. D., 1971,Anal. Biochem.
39, 462–477). When using SDS-PAGE with Na-Pi buffer (Weber, K., and Osborn, M., 1969,J. Biol. Chem.
244, 4406–4442), only a dimeric form of the proteolipid (Mr 15,000±1000) was detected. Experimental data indicate that the different patterns of proteolipid separation are related to the presence of the two distinct proteolipid conformations in the SDS solution. 相似文献
108.
Lj. Vitale M. Renko B. Lenarčič V. Turk M. Pokorny 《Applied microbiology and biotechnology》1986,23(6):449-455
Summary A leucine aminopeptidase was purified to homogeneity fromStreptomyces rimosus culture filtrates, which are waste broth of oxytetracycline bioproduction process. Purification procedure includes ultrafiltration
and chromatography on CM-Sephadex, AH-Sepharose and FPLC Mono S column.
The enzyme is a monomer with molecular weight of 27,500 Daltons and pI of 7.3, stable in broad pH range and up to 70°C. It
is a metallo enzyme dependent on Ca2+ ions for its full activity. By its specificity it is a true aminopeptidase active on amino acid amide, arylamide, peptide
and ester bonds. The hydrolysing activity shows preference for leucine at the N-terminal position of substrates, also acts
on aromatic acids and methionine, but does not release glycine, proline, acidic amino acids orD-amino acid residues. 相似文献
109.
Cellulose- and xylan-degrading enzymes of Trichoderma reesei QM 9414 induced by, sophorose, xylobiose, cellulose and xylan were analyzed by isoelectric focusing. The sophorose-induced enzyme system contained two types of endo-1,4--glucanases (EC 3.2.1.4), one specific for cellulose and the other non-specific, hydrolyzing both cellulose and xylan, and exo-1,4--glucanases (cellobiohydrolases I, EC 3.2.1.91), i.e. all types of glucanases that are produced during growth on cellulose. Specific endo-1,4--xylanases (EC 3.2.1.8) present in the cellulose-containing medium were less abundant in the sophorose-induced enzyme system. Xylobiose and xylan induced only specific endo-1,4--xylanases. It is concluded that syntheses of cellulases and -xylanases in T. reesei QM 9414 are under separate control and that the non-specific endo-1,4--glucanases are constituents of the cellulose-degrading enzyme system. 相似文献
110.
Incomplete ischemia of the spinal cord was produced in dogs by 40 min occlusion of the abdominal aorta that was followed by 5–40 min of recirculation. Amino acid incorporation into ribosomes in vitro in the presence of venous blood sera was estimated. The most significant reduction in incorporation was produced by sera of the dogs following a short recirculation period (5–10 min). No significant changes were observed at the end of the ischemic period nor at longer periods of recirculation. The decrease in incorporation might be the consequence of inactivation or absence of a substance stimulating polypeptide synthesis in vitro, normally present in blood sera of intact dogs, that temporarily loses its activity during recirculation. 相似文献