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141.
142.
143.
Servais P Martinez J Billen G Vives-Rego J 《Applied and environmental microbiology》1987,53(8):1977-1979
Determination of [H] thymidine incorporation into bacterial DNA versus other macromolecules is usually achieved by NaOH and hot trichloroacetic acid hydrolysis. This procedure was found not to be specific enough. An alternative method founded on DNase treatment is proposed. Under the new method, the fraction of thymidine incorporated into DNA ranged from 10 to 83%. 相似文献
144.
Cytochrome-c oxidase. Subunit structure and proton pumping 总被引:5,自引:0,他引:5
M Brunori G Antonini F Malatesta P Sarti M T Wilson 《European journal of biochemistry》1987,169(1):1-8
This article reviews the significance of the subunit structure of cytochrome-c oxidase in proton pumping and in particular summarizes available evidences for or against a role of subunit III in the control of this important function of the enzyme. 相似文献
145.
146.
Endosymbiotic origin and codon bias of the nuclear gene for chloroplast glyceraldehyde-3-phosphate dehydrogenase from maize 总被引:19,自引:0,他引:19
Henner Brinkmann Pascal Martinez Françoise Quigley William Martin Rüdiger Cerff 《Journal of molecular evolution》1987,26(4):320-328
Summary The nuclei of plant cells harbor genes for two types of glyceraldehyde-3-phosphate dehydrogenases (GAPDH) displaying a sequence divergence corresponding to the prokaryote/eukaryote separation. This strongly supports the endosymbiotic theory of chloroplast evolution and in particular the gene transfer hypothesis suggesting that the gene for the chloroplast enzyme, initially located in the genome of the endosymbiotic chloroplast progenitor, was transferred during the course of evolution into the nuclear genome of the endosymbiotic host. Codon usage in the gene for chloroplast GAPDH of maize is radically different from that employed by present-day chloroplasts and from that of the cytosolic (glycolytic) enzyme from the same cell. This reveals the presence of subcellular selective pressures which appear to be involved in the optimization of gene expression in the economically important graminaceous monocots. 相似文献
147.
The rate of hydrolysis of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [a]pyrene (BPDE) to tetrahydroxy derivatives (tetrols) in the presence of various subcellular fractions of rat liver was investigated. Microsomes and nuclei increased the half-life of BPDE in a concentration-dependent manner whereas cytosol had no such effect. The presence of 1 mg microsomal protein/ml increased the half-life of BPDE from 4 to 60 min at 22 degrees C and from 1.5 to 20 min at 37 degrees C. Nuclei equivalent of 500 micrograms DNA/ml increased the half-life from 1.9 to 3.6 min at 37 degrees C. Liposomes prepared from microsomal lipids mimicked the effect of microsomes indicating that BPDE is stabilized primarily by interacting with lipids. The significance of these interactions for the stability of BPDE in an intact cell system was evaluated by using isolated hepatocytes. In these cells the half-life of BPDE was substantially shorter (1 min at 5 X 10(6) cells/ml) than in buffer (3 min). However, hydrolysis of BPDE to tetrols was a minor reaction (less than or equal to 3% of added BPDE at a cell density greater than or equal to 5 X 10(6) cells/ml) and the main route of elimination (greater than or equal to 75%) was through conjugation with glutathione. 相似文献
148.
J. Ruiz-Herrera J. P. Martinez M. Casanova M. L. Gil R. Sentandreu 《Archives of microbiology》1987,149(2):156-162
Cells from the slime variant of Neurospora crassa were broken in isotonic conditions by use of triethanolamine buffer plus EDTA. After removal of large membranous structures by low-speed centrifugation, chitosomes and secretory vesicles were separated by means of gel filtration, precipitation of membranous contaminants with Concanavalin A, and centrifugation in sucrose or glycerol gradients. Polypeptidic composition of fractions enriched in secretory vesicles or chitosomes was found to be distinct. By these criteria we concluded that chitosomes and secretory vesicles represent different populations of microvesicles. Both microvesicular populations appeared free of endoplasmic reticulum and vacuolar contaminants as demonstrated by determination of appropriate enzymatic markers.Abbreviations ER
Endoplasmic reticulum
- UDP-GlcNAc
uridine-5-diphosphate N-acetyl glucosamine
- GlcNAc
N-acetyl glucosamine
- SDS
sodium dodecyl sulfate
- PMSF
phenyl methyl sulfonyl fluoride
- EDTA
ethylene diamino tetraacetic acid
Investigador Nacional de Mexico. On leave from the Centro de Investigacion y Estudios Avanzados (IPN), and the Universidad de Guanajuato, Gto., Mexico 相似文献
149.
Gianfranco Canti Laura Ricci Ornella Marelli Paola Franco Angelo Nicolin 《Cancer immunology, immunotherapy : CII》1987,24(1):64-67
Summary New antigenic specificities, not detectable on parental cells, have been induced by many investigators in mouse lymphomas by treatment with the antitumor agent 5(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC). The antigens are transmissible, after withdrawal of the drug treatment, as an inheritable character. The mechanism of induction, the molecular nature, and the number of the new antigenic specificities have not been completely elucidated. Four clones from murine leukemia L1210 isolated and expanded in vitro were treated in vivo with DTIC and the new sublines were studied in detail. The four drug-treated sublines studied exhibited strong immunogenicity since they were rejected by syngeneic animals. Immunosuppressed animals challenged with 107 A/DTIC or P/DTIC cells were reciprocally protected by the adoptive transfer of spleen cells from donors that had rejected a lethal challenge of A/DTIC or P/DTIC clones. In a similar fashion, the adoptive transfer of spleen cells obtained from animals that had rejected the Q/DTIC or the R/DTIC clones protected immunosuppressed mice challenged with Q/DTIC or R/DTIC cells. No antitumor activity was observed in cross-protective schedules other than those indicated. It was been concluded that (a) the L1210 leukemia line does not have antigenic cells, (b) four DTIC-treated clone sublines were rejected by compatible hosts, and (c) two mutually exclusive sets of antigens were expressed in four antigenic clone sublines.Research supported in part by P.F.O. Contract Grant from C. N. R., Rome, Italy 相似文献