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51.
烟草愈伤组织器官发生过程中外源激素的作用 总被引:6,自引:0,他引:6
近年来,利用愈伤组织系统在与器官发生有关的形态学、生理学和生物化学研究方面已经取得了一些进展(Thorpe 1980,刘涤 1983)。对烟草愈伤组织系统的研究明确了外源激素对器官发生类型的调节作用(Skoog 1971,Engelke等1973,刘涤等1980)。但是,这些研究仅考虑到外源激素的作用,而对器官发生过程中的其它变化并不了解。最近,Kamada和Harada(1981)比较了胡萝卜体细胞胚发育过程中内源IAA和ABA含量的变化,Noma等(1982)证实形成胚的和不形成胚的细胞间GA_3含 相似文献
52.
The changes of H-D exchange rates upon protein-protein interactions are generally interpreted as a result of the changes of the dynamic properties of the proteins. The effect of trypsin binding on the H-D exchange kinetics of some trypsin inhibitor amide H's was reported (Simon et al., 1984). In this paper the electrostatic potential originating from the trypsin molecule is calculated at the positions of the studied amide H's in the trypsin-trypsin inhibitor complex. We conclude that the observed decrease of the exchange rates is mainly due to the electrostatic field of the trypsin molecule. 相似文献
53.
Y. Mitsui H. Akagawa H. Onishi S. Itoh K. T. Nakamura Y. Iitaka 《Journal of biosciences》1985,8(1-2):481-489
The complex of a bacterial alkaline serine proteinase, subtilisin BPN’, with its proteinaceous inhibitorStreptomyces subtilisin inhibitor is unique in several respects, compared with other similar complexes containing serine proteinases of trypsin family. In addition to the usual antiparallelβ-sheet involving P1-P3 residues of the inhibitor, P4-P6 residues form antiparallelβ-sheet with a previously unnoticed chain segment (the ‘S4-6 site’) of subtilisin. The ‘S4-6 site’ does not exist in serine proteinases of trypsin family, whether of mammalian or microbial origin. Global induced-fit movement seems to occur on the ‘trapped substrate’Streptomyces subtilisin inhibitor: a channel-like structure in SSI remote from the contact region becomes about 2 Å wider upon complexing with subtilisin. Main role of the secondary contact region ofStreptomyces subtilisin inhibitor seems to support the reactive site loop (primary contact region). Steric homology for the two contact regions is so high between the inhibitors ofStreptomyces subtilisin inhibitor family and those of pancreatic secretory trypsin inhibitor-ovomucoid inhibitor family that it seems to favour a divergent evolution and to support the general notion as to the relationship of prokaryotic and eukaryotic genes put forwarded by Doolittle(Nature (London),272, 581, 1978). 相似文献
54.
Kaoru Miyazaki Keisuke Mashima Nobuhiko Yamashita Jinpei Yamashita Takekazu Horio 《In vitro cellular & developmental biology. Plant》1985,21(1):62-66
Summary We have previously reported the transformation by Rous sarcoma virus of a cloned epithelial cell line (BRL) established from
Buffalo rat liver by H. Coon. The nontransformed (BRL) and transformed (RSV-BRL) cells grew at comparable rates in culture,
whereas only the transformed cells were tumorigenic in vivo. We report here on the existence in rat and mouse sera of a growth
inhibitor for the nontransformed BRL cells. The transformed BRL cells (RSV-BRL) were insensitive to this inhibitor. The inhibitory
activity was not prominent in sera from other species of animals tested except for rabbit; this serum inhibited the growth
of RSV-BRL cells more strongly than that of BRL cells. The growth inhibitor was partially purified from rat serum. It is a
protein free of lipid and has a molecular weight of about 220 000. The inhibitor could be separated into three components
of pI 4.6, 5.2 (major) and 5.6 by isoelectric electrophoresis.
EDITOR'S STATEMENT Although compelling theoretical arguments sometimes can be made for the likely existence of growth-inhibitory
substances of physical relevance in the control of cell proliferation, experiments aimed at identifying and studying such
factors often are difficult to design and interpret, and little strong data exists to suggest that growth-inhibitory substances
are important regulatorsin vivo. The information presented in this paper represents a start toward developing a useful system for studying growth-inhibitory
factor. David W. Barnes 相似文献
55.
Dov Borovsky 《Archives of insect biochemistry and physiology》1985,2(2):145-159
Proteolytic enzymes were characterized in the midgut and the excreta of the stable fly Stomoxys calcitrans (L) with proteins, synthetic substrates, and inhibitors. Inhibition studies suggested trypsinlike activity in sugar-fed fly midguts, whereas excreta and blood-fed fly guts exhibited other proteases. Trypsinlike activity in midguts removed 20 and 30 h after a blood meal increased from 20% to 50% of the total proteolytic enzymes present. Trypsinlike activity was inhibited with human sera, trypsin-specific inhibitors, and a protein isolated from the stable fly thorax. When human albumin and globulin fractions were incubated with trypsinlike enzymes isolated from the midgut and excreta, the albumin fraction was less inhibitory than the globulin fractions and was readily hydrolyzed by the proteolytic enzymes. These results may indicate that the proteolytic enzymes produce an abortive complex with the globulin fractions of the sera. Such a complex may explain the temporary inhibition of proteolysis by the blood meal. Soybean trypsin inhibitor fed to stable flies caused 50% inhibition in proteolytic activity in the midguts of sugar-fed stable flies and 25% inhibition in the midguts of blood-fed stable flies. Complete inhibition of proteolytic enzyme activity was achieved only in vitro. pH profiles of proteolytic enzyme activity isolated from the excreta of blood-fed stable flies indicated that several proteolytic enzymes were excreted. 相似文献
56.
Cholesterol Synthesis and Nerve Regeneration 总被引:1,自引:1,他引:0
Anne M. Heacock Paul D. Klinger Edward B. Seguin Bernard W. Agranoff 《Journal of neurochemistry》1984,42(4):987-993
Abstract: In this report, we examine the requirement of cholesterol biosynthesis and its axonal transport for goldfish optic nerve regeneration. Cholesterol, labeled by intraocular injection of [3 H]mevalonolactone. exhibited a delayed appearance in the optic tectum. Squalene and other minor components were labeled but not transported. Following optic nerve crush, the amount of labeled cholesterol transport was elevated, while retinal labeling was not altered relative to control fish. A requirement for cholesterol biosynthesis is inferred from the inhibition of neurite outgrowth in retinal explants caused by the cholesterol synthesis inhibitor, 20, 25-diazacholes-terol. The inhibition of growth could be overcome by addition of mevalonolactone, but not cholesterol, to the medium. Intraperitoneal administration of 200 nmol of dia-zacholesterol resulted in 92-98% inhibition of retinal cholesterol synthesis and accumulation of labeled des-mosterol and other lipids in fish retina and brain which persisted for 2 weeks. Diazacholesterol-treated fish showed no reduction in the amount of lipid-soluble radioactivity transported following intraocular injection of [3 H]mevalonolactone, but there were alterations in the chromatographic pattern of the transported labeled lipids. In contrast to its effects on neurite outgrowth in vitro , diazacholesterol did not inhibit optic nerve regeneration in vivo , as measured both by arrival of labeled rapidly transported protein at the tectum and by time required for the return of visual function. 相似文献
57.
Insulin (100 U/ml) stimulated protein synthesis and PGF2 release in isolated rabbit muscle, but had little effect on the rate of protein degradation. The effect of insulin persisted for at least 5 h after removal of the hormone. Indomethacin, added at the start of the incubation, inhibited the stimulatory effect of insulin on protein synthesis and PGF2 release, but did not block the binding of iodinated insulin. When added 2 h after insulin, indomethacin did not inhibit the stimulation of protein synthesis but completely inhibited the increase in PGF2 release. The results suggest that the stimulation of protein synthesis by insulin is mediated by metabolites of membrane phospholipids but that these changes are involved during the phase of response that immediately follows the binding of insulin to its receptor. 相似文献
58.
Nobuo Aoki 《Journal of Protein Chemistry》1986,5(4):269-277
Fibrinolytic system is one of the major proteolytic pathways in vivo and primarily responsible for dissolution of thrombi. Two enzymes are primarily involved in this proteolytic system; plasminogen activator (PA) and plasmin. Plasmin is formed by a limited proteolysis of plasminogen by PA, which is mainly synthesized by and secreted from vascular endothelial cells. This proteolytic process proceeds physiologically only on the surface of fibrin. Thus, initiation and progression of the fibrinolytic process depend on the function of endothelial cells and fibrin formation. Endothelial cells may also synthesize and excrete PA inhibitor (PAI) which inhibits immediately, PA once released. The rates of synthesis and excretion of PA and PAI by endothelial cells are regulated by various factors. Among them, thrombin stimulates the release of PA whereas activated protein C may decrease the release of PAI. Thus, both enzymes enhance fibrinolytic potential. PA which has escaped from inhibition by PAI binds to fibrin. 2-Plasmin inhibitor (2PI) inhibits the binding of plasminogen to fibrin, thereby suppressing this fibrin-associated plasminogen activation. A part of 2PI is cross-linked to fibrin by activated factor XIII when fibrin is formed, and the 2PI thus cross-linked to fibrin inhibits in situ plasmin formed on fibrin. Thus, 2PI as well as PAI plays a central role in inhibition of fibrinolysis. 相似文献
59.
Arthur I. Aronson 《FEMS microbiology letters》1986,33(1):47-50
Abstract Conversion of Bacillus subtilis to protoplasts resulted in the release of 70–80% of the total protease inhibitor activity. Inhibitor fractions contained a polypeptide of approx. 15 kDa which reacted with inhibitor antibody. There was no release of protease inhibitor into the medium by sporulating cells, by osmotic shock of cells nor by washing with high concentrations of salt. The release of inhibitor activity was selective in that only 10–20% of the total protein, and < 10% of the glutamine synthetase activity was found in the protoplast supernatant. The inhibitor could be localized near the cell surface and function in cell protection. 相似文献
60.
Selective expression of a probable amylase/protease inhibitor in barley aleurone cells: Comparison to the barley amylase/subtilisin inhibitor 总被引:5,自引:0,他引:5
We have cloned and sequenced a 650-nucleotide cDNA from barley (Hordeum vulgare L.) aleurone layers encoding a protein that is closely related to a known -amylase inhibitor from Indian finger millet (Eleusine coracana Gaertn.), and that has homologies to certain plant trypsin inhibitors. mRNA for this probable amylase/protease inhibitor (PAPI) is expressed primarily in aleurone tissue during late development of the grain, as compared to that for the amylase/subtilisin inhibitor, which is expressed in endosperm during the peak of storage-protein synthesis. PAPI mRNA is present at high levels in aleurone tissue of desiccated, mature grain, and in incubated aleurone layers prepared from rehydrated mature seeds. Its expression in those layers is not affected by either abscisic acid or gibberellic acid, hormones that, respectively, increase and decrease the abundance of mRNA for the amylase/subtilisin inhibitor. PAPI mRNA is almost as abundant in gibberellic acid-treated aleurone layers as that for -amylase, and PAPI protein is synthesized in that tissue at levels that are comparable to -amylase. PAPI protein is secreted from aleurone layers into the incubation medium.Abbreviations ABA
abscisic acid
- ASI
barley amylase/subtilisin inhibitor
- bp
nucleotide base pairs
- Da
dalton
- dpa
days post anthesis
- GA3
gibberellic acid
- PAPI
probable amylase/protease inhibitor
- poly(A)RNA
polyadenylated RNA
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis 相似文献