全文获取类型
收费全文 | 2819篇 |
免费 | 115篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 25篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 27篇 |
2017年 | 32篇 |
2016年 | 36篇 |
2015年 | 99篇 |
2014年 | 87篇 |
2013年 | 129篇 |
2012年 | 181篇 |
2011年 | 182篇 |
2010年 | 99篇 |
2009年 | 88篇 |
2008年 | 149篇 |
2007年 | 138篇 |
2006年 | 130篇 |
2005年 | 159篇 |
2004年 | 144篇 |
2003年 | 128篇 |
2002年 | 143篇 |
2001年 | 60篇 |
2000年 | 65篇 |
1999年 | 65篇 |
1998年 | 30篇 |
1997年 | 35篇 |
1996年 | 21篇 |
1995年 | 33篇 |
1994年 | 27篇 |
1993年 | 32篇 |
1992年 | 60篇 |
1991年 | 45篇 |
1990年 | 48篇 |
1989年 | 42篇 |
1988年 | 32篇 |
1987年 | 34篇 |
1986年 | 31篇 |
1985年 | 31篇 |
1984年 | 25篇 |
1983年 | 23篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 24篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1967年 | 8篇 |
排序方式: 共有2934条查询结果,搜索用时 546 毫秒
71.
An NADPH-hepatoredoxin reductase was purified from mitochondria of rabbit hepatocytes. The optical absorption spectrum showed a typical flavoprotein. The NADPH-hepatoredoxin reductase has an FAD as a coenzyme and the molecular weight of the NADPH-hepatoredoxin reductase was estimated to be 51000 by SDS-polyacrylamide gel electrophoresis. The NADPH-hepatoredoxin reductase was immunochemically similar to NADPH-adrenodoxin reductase of bovine and pig adrenocortical mitochondria, but not NADPH-cytochrome P-450 reductase of rabbit liver microsomes. The NADPH-cytochrome c reductase activity of the NADPH-hepatoredoxin reductase and hepatoredoxin complex, unlike NADPH-cytochrome P-450 reductase, was decreased by increasing ionic strength. 相似文献
72.
A cofactor protein required for actin activation of myosin Mg2+ATPase activity in leukemic myeloblasts 总被引:2,自引:0,他引:2
The Mg2+ATPase activity of the myosin of a myeloid leukemia cell line (Ml) was not activated by purified Ml actin or by muscle actin alone. Activation required the presence of a cellular fraction as a cofactor in addition to the actin, when Mg2+ATPase was stimulated as much as 20-fold. The cofactor was partially purified and characterized. 1) Its molecular weight was estimated as 45,000 to 55,000 daltons by gel filtration and as 45,000 daltons by SDS polyacrylamide gel electrophoresis. 2) The cofactor was a light chain kinase that phosphorylated both the L1 and L2 light chains of the Ml cell myosin, but not the L3 or heavy chain. 相似文献
73.
Tomoyuki Ichikawa 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1980,135(2):183-189
Summary Extracts of the carp urophysis elicit a marked decrease in urine flow in the anaesthetized hydrated rat. Reproducible dose-dependent responses are obtained within the range of 2 to 16 g of acetonedried carp urophysis per 100 gBW of the rat. The carp urophysial antidiuretic substance is peptidic, and is different from the neurohypophysial peptides. The bulk of antidiuretic activity is located in the electrondense granules in the carp urophysis. The antidiuretic substance, probably urotensin I, is found generally in teleost urophyses. The activity per mg of acetonedried urophysis is higher in freshwater teleost species than in seawater species.Abbreviations
AVP
arginine vasopressin
-
AVT
arginine vasotocin
-
LVP
lysine vasopressin
-
US
carp urophysial standard preparation 相似文献
74.
A seroepidemiological survey of varicella was made in the Nagoya area by the neutralization (NT) test. Of 1,473 recorded cases of varicella, 81.4% were under 6 years old and 9.6% were under one year old; of the 168 recorded cases under one year old, about 30% were under 5 months old. Examination of 11 pairs of mother and cord sera and 13 pairs of mother and infant sera showed that transfer of NT antibody was in general good, even in babies that were small for their age or smnall at birth after 28 weeks gestation. The transferred maternal antibody decreased rapidly, becoming undetectable in babies of 4 months old. Then with increase in age the percentgage of seropositive children gradually increased, being 53.3% at 4 to 5 years old, and 100% in those of over 9 years old, with a temporary decrease in young adults in their twenties. 相似文献
75.
76.
77.
Thin sections of the spore of Bacillus thiaminolyticus Matsukawa and Misawa show a characteristic surface structure with five ridges, and a series of three district layers. The outer layer of the spore coat was peeled off by SDS sonic treatment, and than the middle layer was solubilized by alkali extraction of the SDS sonic-treated spore. The spores subjected to these treatments were still refractile, heat resistant, and contained dipicolinic acid, but lost their resistance to mechanical shock. 相似文献
78.
Lawrence W. Adler Tomio Ichikawa Syed M. Hasan Tomofusa Tsuchiya Barry P. Rosen 《Journal of cellular biochemistry》1977,7(1):15-27
Membrane vesicles of Escherichia coli can be produced by 2 different methods: lysis of intact cells by passage through a French pressure cell or by osmotic rupturing of spheroplasts. The membrane of vesicles produced by the former method is everted relative to the orientation of the inner membrane in vivo. Using NADH, D-lactate, reduced phenazine methosulfate, or ATP these vesicles produce protonmotive forces, acid and positive inside, as determined using flow dialysis to measured the distribution of the weak base methylamine and the lipophilic anion thiocyanate. The vesicles accumulate calcium using the same energy sources, most likely by a calcium/proton antiport. Calcium accumulation, therefore, is presumably indicative of a proton gradient, acid inside. The latter type of vesicle, on the other hand, exhibits D-lactate-dependent proline transport but does not accumulate calcium with D-lactate as an energy source. NADH oxidation or ATP hydrolysis, however, will drive the transport of calcium but not proline in these vesicles. Oxidation of NADH or hydrolysis of ATP simultaneous with oxidation of D-lactate does not result in either calcium or proline transport. These results suggest that the vesicles are a patchwork or mosiac, in which certain enzyme complexes have an orientation opposite to that found in vivo, resulting in the formation of electrochemical proton gradients with an orientation opposite to that found in the intact cell. Other complexes retain their original orientation, making it possible to set up simultaneous proton fluxes in both directions, causing an apparent uncoupling of energy-linked processes. That the vesicles are capable of generating protonmotive forces of the opposite polarity was demonstrated by measurements of the distribution of acetate and methylamine (to measure the ΔpH) and thiocyanate (to measure the Δψ). 相似文献
79.
Relationship between phosphate content and immunochemical properties of subfractions of bakers'' yeast mannan. 总被引:3,自引:3,他引:0 下载免费PDF全文
The mannan of bakers' yeast (Saccharomyces cerevisiae) was fractionated on a column of diethylaminoethyl-Sephadex into five subfractions. Phosphate content of these mannan subfractions was proportional to the concentration of NaCl solutions used in the chromatographic separation. Quantitative precipitin reactions showed that the serological reactivities of the subfractions were proportional to the content of phosphate. The result of acetolysis study showed that the amounts of mannotetraose and phosphate-containing oligosaccharide fractions increased proportionally to the acidity, whereas the amount of mannose decreased inversely. The results from quantitative precipitin reaction tests and acetolysis study demonstrated that both phosphate contents and multiplicity of branching moieties of mannan subfractions increased proportionally, i.e., micro-heterogeneity concerning the acidity comprised in the parent bulk mannan is not attributable merely to the coexistence of molecular species containing different amounts of phosphate but also to the presence of more of the branching moieties. 相似文献
80.
Pig NADPH-adrenodoxin reductase was crystallized from pig adrenocortical mitochondria and its physicochemical properties were investigated. Pig NADPH-adrenodoxin reductase is a typical flavoprotein. Its optical absorption spectrum showed peaks at 272, 377, and 450 nm in the oxidized form. The adrenodoxin reductase contained one FAD per mol. The molecular weight was 49,000. The isoelectric points of the adrenodoxin reductase and its complex with adrenodoxin were 5.3 and 4.6, respectively. Pig NADPH-adrenodoxin reductase, unlike bovine NADPH-adrenodoxin reductase, was found to be free of carbohydrate. The fluorescences of tryptophanyl residues and FAD of the adrenodoxin reductase were quenched by holo- and apo-adrenodoxins. The NADPH-binding site of the adrenodoxin reductase was examined by photooxidation and selective chemical modifications with diethyl pyrocarbonate and sulfhydryl reagents. The results indicate that a histidyl and a cysteinyl residue of the adrenodoxin reductase are essential for the NADPH-binding site. The circular dichroism spectrum of the adrenodoxin reductase showed negative ellipticity in the visible region. Spur formation was observed between pig and bovine NADPH-adrenodoxin reductases against the antibody to bovine NADPH-adrenodoxin reductase in Ouchterlony double-diffusion agar plates. The antibody did not interact with spinach ferredoxin-NADP+ reductase. 相似文献