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61.
Root treatments of barley (Hordeum distichum L.) plants with 10-7 to 10-4 M abscisic acid (ABA) caused an increase in proline content, especially at higher concentrations, within 2–3 h. Even 3 h after the removal of ABA from the medium the plants continued to accumulate proline. The higher the concentration of the ABA, the higher was the proline level at 6 h. When the highest ABA concentration, 10-4 M, was tested with polyethylene glycol (PEG) (-5.0 bars) in the medium, the ABA treatment resulted in a higher proline content than in control plants. The treatments PEG alone and PEG + ABA resulted in heavy accumulation of proline, especially, 3 h after releasing the plants from the stress. The proline content in PEG+ABA-treated plants was always higher than plants treated with PGE or ABA alone. In peas (Pisum sativum L. cv Alaska) the same trend occurred although to a lesser degree. These findings indicate an influence of ABA on proline accumulation in water-stressed plants.Abbreviations ABA
abscisic acid
- PEG
polyethylene glycol
- RWC
relative water content 相似文献
62.
Niels H. Andersen Shoji Imamoto Donald H. Picker 《Prostaglandins & other lipid mediators》1977,14(1):61-101
With the report given herein all diastereomers of PGF2, PGE2, and PGD2 which bear the naturally recognized 15-S hydroxylated center, whether in the natural or -prostanoic acid skeleton, have been prepared by a route involving initial introduction of the carboxyl (α) chain (1). A major advantage of the initial α-ylation+ route is the facile reduction of the 13,14-en-15-one system with methanolic NaBH4 which proceeds without competing 1,4-reduction. The products are thus free of 13,14-dihydro-PG2 contaminants (2). The initial pharmaco logical evaluation of these diastereomers will be submitted for publication in this journal (3). 相似文献
63.
In a previous experiment, rabbits and goats were immunized with boiled and ethanol precipitated (BE) bovine kidney antigen, and the specificity of the antibodies produced was compared (Andersen 1975). The caprine sera were species specific while the rabbit sera, however, cross-reacted with BE antigens from other ruminant species. Sera from 2 rabbit littermates differed somewhat in that 1 serum seemed to be mainly species specific giving only weak reactions against BE antigens from kidney and spleen from other ruminants, whilst the other serum was more organ specific and reacted equally with homologous and heterologous kidney antigens. 相似文献
64.
Thirteen strains of mycobacteria isolated from deer and various species of wild birds were analysed by gas chromatography (GG) for cellular fatty acids and by thin-layer chromatography (TLG) for polar lipids. These strains were compared to reference strains of Mycobacterium avium, M. para tuberculosis and M. mal-moense. All the examined strains exhibited a generally similar fatty acid pattern characterized by relatively large amounts of hexadenca-noate (16:0), octadecenoate (18:1), octadecanoate (18:0) and 10-me-thyl-octadecanoate (tuberculostearic acid, 10-Me-18:0). Several additional acids were also generally present but in smaller amounts. By means of small but distinct differences in fatty acid composition, the wild animal isolates could be distinguished from both M. paratuber-culosis and M. malmoense but not from M. avium. The TLG polar lipid patterns on the other hand separated the wild animal isolates into 2 distinct groups of complex and simple polar lipid composition which corresponded to the morphologically smooth and rough types, respectively. The complex patterns of the smooth strains were comparable to those of the M. avium serovars whereas both the rough wild animal isolates and all the M. paratuber-culosis strains showed a simple pattern of polar lipids. Both fatty acid profiles and TLG polar lipid patterns support allocation of the wild animal isolates to the MAIS complex. Moreover, the 2 chemical techniques, particularly the GC procedure, are very useful for a more rapid and precise identification of the slow-growing wild animal mycobacterial isolates which have hitherto been characterized on basis of vague criteria. 相似文献
65.
J A Gingrich P H Andersen M Tiberi S el Mestikawy P N Jorgensen R T Fremeau M G Caron 《FEBS letters》1992,312(2-3):115-122
During the course of large scale purification of the D1 dopamine receptor from rat brain, a protein of approximately 87,000 daltons (p87) was observed to copurify with the D1 receptor through four chromatographic steps. To characterize the nature of this protein, bovine and rat cDNA clones were isolated and sequenced. The bovine and rat clones were highly conserved (98.5% identity). Each clone possessed an open reading frame of 2226 base pairs encoding a protein of 742 amino acids (calculated MW of 82,500), containing three stretches of peptide sequence obtained from p87 sequence analysis. Comparison of the deduced peptide sequence of this protein with those found in available databanks revealed that it was a novel protein related to the family of nutrient transport proteins from eukaryotes and bacteria, including, the mammalian facilitated glucose transporters, the yeast transporters for maltose, lactose, and glucose, and the proton-driven bacterial transporters for arabinose, xylose, and citrate. In addition p87 also shares with these transporters a similar hydropathicity profile that suggests the presence of 12 transmembrane segments. The mRNA for p87 appears to be localized primarily, if not exclusively, to the central nervous system. Northern blot analysis reveals a message of approximately 4.8 kb in cortex, hippocampus, brain stem, and cerebellum, but no detectable signal in peripheral tissues such as spleen, liver, kidney, lung, heart, or skeletal muscle. Evidence form Western blot analysis and immunohistochemistry suggests that this protein may be expressed in intracellular organelles or the membrane of synaptosomes rather than plasma membrane. Based on its structure and properties, p87 appears to define a new class of transporter-like proteins. 相似文献
66.
Site-specific mutagenesis was used to analyse the role of the residue, Glu309, in the function of the Ca(2+)-ATPase of frog skeletal muscle sarcoplasmic reticulum by substitution with Ala or Lys. At pH 6.0, 100 microM Ca2+ was unable to prevent phosphorylation from Pi, consistent with previous observations on the Ca(2+)-ATPase of rabbit fast twitch muscle [Clarke, D.M., Loo, T.W, Inesi, G. and MacLennan, D.H. (1989) Nature 339, 476-478]. At neutral pH, however, micromolar concentrations of Ca2+ were sufficient to inhibit phosphorylation of the Glu309----Lys mutant from inorganic phosphate, suggesting that at least one high-affinity Ca2+ site was relatively intact in this mutant. The Glu309----Lys mutant was unable to form a phosphoenzyme from ATP at all Ca2+ concentrations studied (up to 12.5 mM), whereas phosphorylation of the Glu309----Ala mutant occurred at 12.5 mM Ca2+, but not at Ca2+ concentrations in the submillimolar range. Kinetic studies demonstrated a reduced rate of dephosphorylation of the E2P intermediate in the Glu309----Lys mutant. A less pronounced stabilization of E2P was observed with the Glu309----Ala mutant, suggesting a possible role of the charge at the position of Glu309 in phosphoenzyme hydrolysis. 相似文献
67.
68.
Site-specific mutagenesis was used to replace Glu309, Glu771, and Asp800 in the Ca(2+)-ATPase of rabbit fast twitch muscle sarcoplasmic reticulum with their corresponding amides. These residues are predicted to lie in the transmembrane domain and have been suggested as oxygen ligands for Ca2+ binding at high affinity sites (Clarke, D. M., Loo, T. W., Inesi, G., and MacLennan, D. H. (1989) Nature 339, 476-478). The Glu309----Gln and Asp800----Asn mutants were unable to form a phosphoenzyme from ATP at the Ca2+ concentrations examined (up to 12.5 mM), whereas the Glu771----Gln mutant phosphorylated from ATP at 2.5 mM Ca2+. In all three mutants, Ca2+ at concentrations well below 12.5 mM prevented or inhibited phosphorylation with Pi, suggesting that at least one calcium-binding site was functioning in each mutant. In the mutants Glu309----Gln and Glu771----Gln, the ADP-insensitive phosphoenzyme intermediate was unusually stable, as indicated by a very low rate of dephosphorylation observed in kinetic experiments and by an increased apparent affinity for Pi determined in equilibrium phosphorylation experiments. These data indicate a central role of Glu309 and Glu771 in the energy-transducing conformational changes and/or in the activation of phosphoenzyme hydrolysis. 相似文献
69.
Site-specific mutagenesis was used to replace Gly310, Gly770, and Gly801, located in the transmembrane domain of the sarcoplasmic reticulum Ca(2+)-ATPase, with either alanine or valine. In addition, Gly310 was substituted with proline. In the Gly310----Ala mutant, the Vmax for Ca2+ transport and ATPase activity was reduced to about 40% of the wild type activity, but the apparent Ca2+ affinity was close to normal. The Gly310----Val and Gly310----Pro mutants were devoid of Ca2+ transport or ATPase activity and displayed more than a 20-fold reduction in the apparent Ca2+ affinities measured in the phosphorylation assays with either ATP or Pi. In these mutants, the rate of phosphoenzyme hydrolysis was reduced, and the ADP-insensitive phosphoenzyme intermediate accumulated. The apparent affinity for Pi was increased in the absence, but not in the presence, of dimethyl sulfoxide. The properties of this new class of Ca(2+)-ATPase mutants ("E2/E2P" type) are consistent with a conformational state in which the protein-phosphate interaction is stabilized and the Ca(2+)-protein interaction is destabilized. The Gly770----Ala mutant transported Ca2+ with a Vmax close to that of the wild type, but displayed more than a 20-fold reduction of apparent Ca2+ affinity. The Gly770----Val mutant was not phosphorylated from either ATP or Pi. The Gly801----Ala mutant transported Ca2+ with a Vmax of 126% that of the wild type, hydrolyzed ATP at the same Vmax as the wild type in the presence of calcium ionophore, and displayed a 3-fold reduction in apparent Ca2+ affinity. The Gly801----Val mutant was unable to transport Ca2+ and to be phosphorylated from ATP, even at a Ca2+ concentration of 1 mM, but Ca2+ in the micromolar range inhibited phosphorylation from Pi. The ability to bind ATP with normal affinity was retained. The properties of this mutant are consistent with a disruption of one of the two Ca2+ binding sites required for phosphorylation with ATP. 相似文献
70.
Summary The flagella of the pigmented algaEpipyxis pulchra (Chrysophyceae) were observed with image enhanced video microscopy to play an active role in gathering, physically seizing and selecting prey prior to phagocytosis. Vegetative unicells of this sessile, freshwater species possess two structurally and functionally distinct flagella, both active in feeding. During prey gathering the long flagellum, which is adorned with stiff hairs, beats rapidly to direct a strong water current towards the cell while the short, smooth flagellum moves very little. When a potential food particle is drawn by the current to contact the flagellar surfaces, the long flagellum stops beating and positions itself, in concert with the short flagellum, to seize the prey between them. Both flagella then briefly rotate the prey before selecting or rejecting it. If rejected, the particle is discarded by the coordinated activity of both flagella. If selected as food, the prey is held in place until a complex collecting cup emanates out from a position near the basal bodies and engulfs it. The cup plus enclosed food particle, now a food vacuole, is then retracted back to the cell proper. 相似文献