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21.
Yuzuru Matsuda Nobuo Nakanishi Geneva Dickens Gordon Guroff 《Journal of neurochemistry》1986,47(6):1728-1734
Soluble extracts from nerve growth factor (NGF)-stimulated PC12 cells prepared by alkaline lysis show a two- to 10-fold greater ability to phosphorylate the 40S ribosomal protein S6 than do extracts from control cells. The alkaline lysis method yields a preparation of much higher specific activity than does sonication. Half-maximal incorporation of 32P from [32P]ATP into S6 occurred after 4-7 min of NGF treatment. The partially purified NGF-sensitive S6 kinase has a molecular weight of 45,000. It is not inhibited by NaCl, chlorpromazine, or the specific inhibitor of cyclic AMP (cAMP)-dependent protein kinase, nor is it activated by addition of diolein plus phosphatidylserine. Trypsin treatment of either crude extracts or partially purified S6 kinase from control or NGF-treated cells was without effect. These data suggest that the S6 kinase stimulated by NGF is neither cAMP-dependent protein kinase or protein kinase C nor the result of tryptic activation of an inactive proenzyme. Treatment of intact cells with dibutyryl cAMP or 5'-N-ethylcarboxamideadenosine also increases the subsequent cell-free phosphorylation of S6. This observation suggests that cAMP-dependent protein kinase may be involved in the phosphorylation of S6 kinase. 相似文献
22.
Y Ueno T Miyawaki H Seki A Matsuda K Taga H Sato N Taniguchi 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(1):180-184
Ontogenic development and the lymphokine responsiveness of human NK cell activity against K562 target cells in peripheral blood lymphocytes were evaluated in fetuses, premature infants, and term neonates by using a 4-hr 51Cr-release assay. Basal NK activity and NK boosting by lymphokines were comparatively assayed after an 18-hr incubation with medium alone, recombinant human IFN-gamma (1000 U/ml), and recombinant human IL 2 (25 U/ml), respectively. Lymphocytes from 20-wk-old fetuses lacked NK cell activity even after the pretreatment with IFN-gamma. Low, but significant levels of NK activity and NK boosting by IFN-gamma were observed in premature infants after 27 wk of gestation, with a progressive intrauterine maturation of these activities. Both basal NK activity and NK boosting by IFN-gamma in term neonates were still lower than those of adult controls. The grade of NK boosting by IFN-gamma appeared to depend on the development of basal NK activity. Contrary to IFN-gamma, IL 2 could induce marked NK activity even in 20-wk-old fetuses who lacked both basal and IFN-gamma inducible NK activities. NK boosting by IL 2 was much more efficient than that by IFN-gamma at any period of human life. The facts that IL 2-induced NK boosting could occur without any appreciable production of IFN-gamma in neonatal lymphocytes, and that ample neutralizing doses of anti-IFN-gamma antibody hardly suppressed IL 2-mediated NK boosting even in adult lymphocytes, indicated that the effect of IL 2 on NK boosting might be independent of IFN-gamma production. On the basis of the ontogenic differences in the development of the lymphokine responsiveness of NK cell activity and on the different NK boosting mechanisms of these lymphokines it was suggested that so-called human "pre-NK cells" might be divided into IFN-gamma sensitive and IL 2-sensitive cells. Whether these cell populations belong to different cell lineages or different maturation stages of the same cell line, however, remains unsettled. 相似文献
23.
The xyloglucan present in the 24% KOH extract of the cell wallsof suspension-cultured rice cells was characterized by fragmentationanalysis with Trichoderma viride cellulase and Aspergillus oryzaeß-D-glucosidase. The xyloglucan is composed mainlyof the following oligosaccharide units: Results showed that the xyloglucan of suspension-cultured ricecells is more extensively branched than is that of rice seedlings.Another structural characteristic of the former xyloglucan isthe presence of D-galactosyl-D-xylosyl side chains that arenot found in the latter. (Received June 15, 1984; Accepted January 11, 1985) 相似文献
24.
Amino acid sequences of the two kinds of regulatory light chains of adductor smooth muscle myosin from Patinopecten yessoensis 总被引:1,自引:0,他引:1
Smooth muscle myosin from scallop (Patinopecten yessoensis) adductor muscle contains two kinds of regulatory light chains (regulatory light chains a and b), and myosin having regulatory light chain a is suggested to be suitable for inducing "catch contraction" rather than myosin having regulatory light chain b (Kondo, S. & Morita, F. (1981) J. Biochem. 90, 673-681). The amino acid sequences of these two light chains were determined and compared. Regulatory light chain a consists of 161 amino acid residues, while regulatory light chain b consist of 156 amino acid residues. Amino acid substitutions and insertions were found only in the N-terminal regions of the sequences. The structural difference between the two light chains may contribute to the functional difference between myosins having regulatory light chains a and b. 相似文献
25.
Antibody was prepared against the 25,000-dalton tryptic fragment of subfragment-1 from skeletal muscle myosin. The antibody was found to inhibit the Mg2+-ATPase activity and the initial P1-burst of the ATPase. The antibody suppressed the ATP-induced fluorescence enhancement of S-1, though it did not suppress the binding of ATP to S-1. The acto-S-1 ATPase activity was also inhibited by the antibody. These results suggest that there is a site in the 25K fragment region responsible for the transition of the myosin-ATP complex to another high energy complex. 相似文献
26.
Rabbit factor H, a control protein of the alternative complement pathway, was isolated from rabbit serum by polyethylene glycol precipitation, DEAE-Sephacel chromatography, and gel chromatography on Sephadex G200. The protein migrated as a single-chain polypeptide with a molecular weight of 160,000 on sodium dodecyl sulfate-gel electrophoresis with Laemmli's buffer system, but hardly migrated into the gel with Fairbanks' buffer system. Physical and chemical properties of rabbit H were similar to those of human H, except that fragments produced by limited tryptic digestion from rabbit H had different molecular sizes from those produced from human H. Significant species-specificity was observed in the functional activity of factor H; activation of the alternative complement pathway was inhibited more efficiently with homologous H than with heterologous H. In contrast, factor H inhibited the hemolysis of homologous erythrocytes less than that of heterologous erythrocytes. 相似文献
27.
28.
Y Wada A Hayashi F Masanori I Katakuse T Ichihara H Nakabushi T Matsuo T Sakurai H Matsuda 《Biochimica et biophysica acta》1983,749(3):244-248
Molecular secondary ion mass spectrometry has characterized the structure of a new fetal hemoglobin variant, Hb F Izumi, without separation of peptides or amino acid analysis. First, the mass spectrum of a tryptic digest of the abnormal gamma globin revealed a decreased by 72 mass units in the molecular mass of peptide T-1,2, indicating the presence of a Glu leads to Gly substitution. Next, the analysis of the digest produced by the addition of staphylococcal protease, which specifically cleaves glutamyl peptide bonds, determined the site of substitution at 6th glutamic acid residue in peptide T-1,2 which contains two glutamic acid residues. Since this mass spectrometric approach provides digitalized data on peptide analysis, we call it 'digit printing'. The high sensitivity of this technique is especially promising for the analysis of molecular abnormality in various genetic disorders. 相似文献
29.
Inhibition of neuronal sodium and potassium ion activated adenosinetriphosphatase by pyrithiamin 总被引:1,自引:0,他引:1
Since one of the electrophysiological effects of pyrithiamin, an antimetabolite of thiamin, suggested an interference with sodium pump mechanisms, the effect of pyrithiamin on Na+,K+-ATPase was investigated. We found that whereas preincubation of the antimetabolite with nonneuronal preparations of Na+,K+-ATPase produced only minimal inhibition, the enzyme derived from brain preparations was markedly inhibited. This inhibition could be prevented by thiamin but not reversed. The kinetic study showed that pyrithiamin acts in a noncompetitive manner with respect to the activation of the enzyme by ATP, Na+, and K+. Pyrithiamin inhibited Na+-dependent phosphorylation and K+-stimulated phosphatase as well as ouabain binding, and these inhibitions were parallel with that of the overall Na+,K+-ATPase reaction. In addition, the antimetabolite caused a significant change in the turbidity of the enzyme suspension. The results suggest that pyrithiamin may induce a structural change of the enzyme complex. 相似文献
30.
System for the Investigation of the Bacteriophage-directed Synthesis of Diphtherial Toxin 总被引:11,自引:1,他引:10 下载免费PDF全文
Lytic corynebacteriophage betahv64(tox+) has been characterized, and methods for studying the expression of its tox(+) gene in nontoxinogenic Corynebacterium diphtheriae strain C7(s)(-)(tox-) described. During one cycle of viral growth there was a 1 million-fold increase in extracellular toxin. Both the conditions of the experiment and the use of purified phage, free from toxin, support the conclusion that all of the toxin was newly formed. This toxin was immunochemically indistinguishable from standard toxin produced by the PW8(r)(Pdi)(tox+) strain. Chloramphenicol was found to be an effective agent for synchronizing the initiation of viral growth. Once chloramphenicol was removed, intracellular toxin appeared and continued to increase throughout the latent period. Proflavine, added early in the latent period, blocked phage maturation without similarly affecting yields of toxin. Iron exerted a limited inhibitory effect on final toxin levels attained. 相似文献