全文获取类型
收费全文 | 9507篇 |
免费 | 759篇 |
出版年
2021年 | 93篇 |
2020年 | 42篇 |
2019年 | 75篇 |
2018年 | 94篇 |
2017年 | 109篇 |
2016年 | 136篇 |
2015年 | 214篇 |
2014年 | 282篇 |
2013年 | 634篇 |
2012年 | 390篇 |
2011年 | 404篇 |
2010年 | 260篇 |
2009年 | 247篇 |
2008年 | 419篇 |
2007年 | 437篇 |
2006年 | 388篇 |
2005年 | 424篇 |
2004年 | 422篇 |
2003年 | 428篇 |
2002年 | 340篇 |
2001年 | 376篇 |
2000年 | 394篇 |
1999年 | 334篇 |
1998年 | 107篇 |
1997年 | 114篇 |
1996年 | 99篇 |
1995年 | 111篇 |
1994年 | 90篇 |
1993年 | 94篇 |
1992年 | 237篇 |
1991年 | 221篇 |
1990年 | 239篇 |
1989年 | 198篇 |
1988年 | 185篇 |
1987年 | 172篇 |
1986年 | 152篇 |
1985年 | 146篇 |
1984年 | 124篇 |
1983年 | 106篇 |
1982年 | 87篇 |
1981年 | 68篇 |
1980年 | 57篇 |
1979年 | 86篇 |
1978年 | 85篇 |
1977年 | 71篇 |
1976年 | 45篇 |
1975年 | 39篇 |
1974年 | 49篇 |
1973年 | 40篇 |
1972年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
T Oku H Kukidome Y Yamamoto 《Biochemical and biophysical research communications》1983,116(3):803-808
Treatment of platelets or red cells with small amounts of phospholipase C from Clostridium welchii enables both cells, prior to the onset of lysis, to stimulate prothrombin conversion by coagulation factor Xa and Va in the presence of calcium. Phospholipase C treatment of both cells also exposes significant amounts of phosphatidylserine at the outer surface. The level of phosphatidic acid formed from diglycerides produced by phospholipase C action, is similar to that formed in activated platelets upon triggering the phosphatidylinositol cycle. A possible involvement of this cycle to activate platelets to become more procoagulant is discussed. 相似文献
132.
Sequence of heat-labile enterotoxin of Escherichia coli pathogenic for humans. 总被引:20,自引:2,他引:18
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We determined the complete nucleotide sequence of the toxB gene (375 base pairs in length), which encodes the B subunit of heat-labile enterotoxin produced from Escherichia coli pathogenic for humans (hLT). The amino acid sequence of the B subunit of hLT was deduced from the nucleotide sequence. Consequently, it has become possible to study the homology between the B subunits of three similar toxins: hLT, LT produced from E. coli pathogenic for piglets (pLT), and cholera toxin (the latter two sequences have been reported by others). The three B subunits are all 103 amino acids in length. A comparison of the toxB gene and the eltB gene, which encodes the B subunit of pLT, showed a 98% homology at the nucleotide level and a 95% homology at the amino acid (of a precursor) level, indicating the possibility that the two genes share a common ancestor. With respect to the B-subunit sequences, the homologies between hLT and pLT, between hLT and cholera toxin, and between pLT and cholera toxin were 96, 81, and 79%, respectively. Several large common sequences are conserved by the three peptides. In contrast, no sequences are present in both pLT and cholera toxin but missing in hLT. 相似文献
133.
S Yamamoto 《The International journal of biochemistry》1983,15(10):1279-1282
Some differences between the effects of oxalate and oxamate were observed. The oxalate formed the stable tetramers and some aggregates, while the oxamate formed the mixture of dimers, tetramers, octamers and aggregates. The ratios between these molecular forms were different as the oxamate concentration was changed. In the coexistence of inhibitors and pyruvate, pyruvate may act to decrease the molecular weight and to increase the amount of aggregates. The lower molecular weight may be caused by the existence of the active complex, Ed N S1. The effect of the exchange between pyruvate and oxamate bound with enzyme complexes may be expected. 相似文献
134.
Amino acid sequences of two trypsin inhibitors from winged bean seeds (Psophocarpus tetragonolobus (L)DC.) 总被引:1,自引:0,他引:1
The trypsin inhibitor (WTI-1) purified from winged bean seeds is a Kunitz type protease inhibitor having a molecular weight of 19,200. WTI-1 inhibits bovine trypsin stoichiometrically, but not bovine alpha-chymotrypsin. The approximate Ki value for the trypsin-inhibitor complex is 2.5 X 10(-9) M. The complete amino acid sequence of WTI-1 was determined by conventional methods. Comparison of the sequence with that of soybean trypsin inhibitor (STI) indicated that the sequence of WTI-1 had 50% homology with that of STI. WTI-1 was separated into 2 homologous inhibitors, WTI-1A and WTI-1B, by isoelectric focusing. The isoelectric points of WTI-1A and WTI-1B were 8.5 and 9.4, respectively, and their sequences were presumed from their amino acid compositions. 相似文献
135.
Energy transfer between fluorescent dyes attached to Ca2+,Mg2+-ATPase in the sarcoplasmic reticulum 总被引:1,自引:0,他引:1
Sarcoplasmic reticulum (SR) isolated from rabbit skeletal muscle was solubilized with a nonionic detergent, dodecyl octaethyleneglycol monoether (C12E8), at a weight ratio of detergent to protein of greater than 10, so that the Ca2+, Mg2+ dependent ATPase existed mainly in a monomeric form (7). The solubilized ATPase was reacted with 10 microM N-1-P or 5 microM DACM in the presence of 5 mM CaCl2, 0.4 M KCl, 20% glycerol and 50 mM TES at pH 7.5 and 20 degrees C. Under these conditions, about 1 mol of N-1-P was incorporated into 10(5) g SR protein on 10 min incubation and 1 mol of DACM was incorporated into the same amount of SR on 5 min incubation. Analysis of the tryptic digest of the N-1-P- or DACM-labeled. ATPase on SDS polyacrylamide gel revealed that almost all the fluorescence was associated with the 30K m.w. subfragment of the ATPase protein. Even when the amount of the probe incorporated into SR-ATPase was increased from 1 to 3 mol per 10(5) g SR protein, all was incorporated into the 30K subfragment. Both the activities of formation and decomposition of the phosphorylated intermediate (EP) were unaffected by these modifications. When the separately labeled ATPases were mixed together in the presence of C12E8 and the detergent was removed by incubation with Bio-Beads SM-2, a significant amount of fluorescence energy transfer was observed between N-1-P and DACM. However, energy transfer did not occur when the labeled ATPases were mixed after removal of C12E8.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
136.
Among several intracellular protease tested, cathepsin H transformed leukotriene D4 to E4 with a release of glycine in a stoichiometric quantity. Under the optimal conditions the rate of leukotriene D4 transformation by cathepsin H was about 3% of the hydrolysis rate of alpha-N-benzoyl-DL-arginine-2-naphthylamide which is commonly utilized as a very efficient substrate to test the peptidase activity of the enzyme. Leukotriene C4 was not transformed to leukotriene D4 by cathepsin H. Neither cathepsin B nor C was active with leukotrienes C4 and D4. 相似文献
137.
K Yamamoto I Maeyama H Kishimoto Y Morio Y Harada K Ishitobi J Ishikawa 《Endocrinologia japonica》1983,30(5):651-656
A 12-year-old Japanese girl with polyostotic fibrous dysplasia and endocrine concomitants, was treated with elcatonin, a synthetic eel calcitonin analogue, 10 MRC unit/twice a week given by intramuscular injection. Significant decreases in 24 hr urinary content of hydroxyproline and other amino acids from bone collagen were observed during the course of treatment over 5 months. This biochemical result suggests that the synthetic eel calcitonin analogue exhibits the therapeutic effect in patients with polyostotic fibrous dysplasia by inhibiting bone resorption. 相似文献
138.
S Yamamoto 《The International journal of biochemistry》1983,15(2):185-190
1. Low enzymatic activities in low pyruvate concentrations and high Km were observed in sodium chloride solutions. 2. The pyruvate inhibition shown by the % activity at 1 mM pyruvate was lower sodium chloride than in 0.1 M sodium phosphate. 3. At 40 degrees C, as compared with results at 20 degrees C, less pyruvate inhibition was observed in phosphate buffer and in sodium chloride solutions. 4. By using the equilibrium constants between dimer and tetramer, a theoretical explanation is proposed for the pyruvate inhibition. In this explanation, it is suggested that the quaternary complex which is composed of tetrameric enzyme, coenzyme and two kinds of pyruvates was the main cause of the pyruvate inhibition. 相似文献
139.
Effects of high osmotic media on the shape and deformability of RBC were examined for determining increasing factors of blood viscosity. Dog blood and Urographin (a hypertonic contrast medium) were used; the plasma osmolality was changed by Urografin suspended in blood. The viscosity was measured for normal RBC and glutaraldehyde-treated RBC suspensions with a cell volume concentration. The RBC deformability was evaluated from the difference in viscosity between the two suspensions. It was shown that normal RBC suspension increased the viscosity with increase in osmolality at high shear rate; hardened RBC suspension decreased the viscosity with increase in osmolality. It was concluded that the RBC deformability decreased with increasing osmolality. 相似文献
140.
Effects of hemolysis, hematocrit, RBC swelling, and flow rate on light scattering by blood in a 0.26 cm ID transparent tube 总被引:1,自引:0,他引:1
The intensity of light scattering by blood in a tube of diameter 0.26 cm was measured with an apparatus devised by us at different angles on an incident cross-sectional plane. Changes in angular distribution of light intensity associated with hemolysis, and changes in hematocrit (Ht), red blood cell (RBC) swelling, and flow rate were plotted on polar coordinates. The dyssymmetry index, defined as the ratio of the intensity of light at 45 degrees to that at 135 degrees, was used to characterize the shape of the diagrams of light scattering. The index decreased with Ht, flow rate, but increased with RBC swelling. It is concluded that light scattering by blood requires intactness of the RBC membrane. Even when the cell membrane is intact, light scattering is subject to changes with the flow rate of blood, presumably due to RBC aggregation. 相似文献