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861.
862.
Arginase expression in peritoneal macrophages and increase in circulating polyamine levels in mice infected with Schistosoma mansoni 总被引:5,自引:0,他引:5
Abdallahi OM Bensalem H Augier R Diagana M De Reggi M Gharib B 《Cellular and molecular life sciences : CMLS》2001,58(9):1350-1357
We investigated the nitric oxide (NO) synthase and arginase pathways in resident peritoneal macrophages of mice infected
with the tropical parasite Schistosoma mansoni. The two enzymes may have opposite effects, insofar as NO may be involved in the killing of the parasite whereas arginase
may stimulate parasite growth via polyamine synthesis. We determined the effects of the infection on the expression and activity
of the two enzymes in macrophages, before and after cytokine activation. Cells from infected mice expressed the hepatic type
I arginase, whereas in control cells, the enzyme was expressed only after cytokine activation, as were NO synthase II and
type II arginase in both groups of cells. Moreover, we found that in infected mice, arginase expression in macrophages was
associated with a ten fold increase in the concentration of circulating ornithine-derived polyamines. This may be of pathological
importance, since parasitic helminths are though to be dependent on their hosts for the uptake and interconversion of polyamines.
Received 13 March 2001; received after revision 4 May 2001; accepted 7 June 2001 相似文献
863.
Recombinant expression of perchloric acid-soluble protein reduces cell proliferation 总被引:3,自引:0,他引:3
Kanouchi H Tachibana H Oka T Yamada K 《Cellular and molecular life sciences : CMLS》2001,58(9):1340-1343
Perchloric acid-soluble protein (PSP) may play an important role in the regulation of cellular physiological functions because
it has been highly conserved throughout evolution; however, this role has not been well elucidated. In previous reports, we
suggested that PSP regulates cell proliferation. In this study, we examined the effect of PSP expression on proliferation
of the normal rat kidney cell line NRK-52E, the rat hepatocyte cell line RLN-10, and the rat hepatoma cell line dRLh-84. Cells
transfected with pcDNA-sense-PSP (pcDNA-S-PSP) over-expressed PSP mRNA and protein, and cell proliferation of the transfected
cells was suppressed compared with that of cells transfected with pcDNA-empty (pcDNA-E). Cell viability of pcDNA-S-PSP-transfected
cells was similar to that of pcDNA-E-transfected cells. Thus, over-expression of PSP suppresses cell proliferation without
any influence on cell viability. These findings are the first to report an inhibitory activity of PSP on cell proliferation.
Received 27 April 2001; received after revision 8 June 2001; accepted 8 June 2001 相似文献
864.
High frequency of homoplasmic mitochondrial DNA mutations in human tumors can be explained without selection 总被引:17,自引:0,他引:17
Coller HA Khrapko K Bodyak ND Nekhaeva E Herrero-Jimenez P Thilly WG 《Nature genetics》2001,28(2):147-150
Researchers in several laboratories have reported a high frequency of homoplasmic mitochondrial DNA (mtDNA) mutations in human tumors. This observation has been interpreted to reflect a replicative advantage for mutated mtDNA copies, a growth advantage for a cell containing certain mtDNA mutations, and/or tumorigenic properties of mtDNA mutations. We consider another possibility-that the observed homoplasmy arose entirely by chance in tumor progenitor cells, without any physiological advantage or tumorigenic requirement. Through extensive computer modeling, we demonstrate that there is sufficient opportunity for a tumor progenitor cell to achieve homoplasmy through unbiased mtDNA replication and sorting during cell division. To test our model in vivo, we analyzed mtDNA homoplasmy in healthy human epithelial tissues and discovered that the model correctly predicts the considerable observed frequency of homoplasmic cells. Based on the available data on mitochondrial mutant fractions and cell division kinetics, we show that the predicted frequency of homoplasmy in tumor progenitor cells in the absence of selection is similar to the reported frequency of homoplasmic mutations in tumors. Although a role for other mechanisms is not excluded, random processes are sufficient to explain the incidence of homoplasmic mtDNA mutations in human tumors. 相似文献
865.
Failure to confirm NOTCH4 association with schizophrenia in a large population-based sample from Scotland 总被引:1,自引:0,他引:1
McGinnis RE Fox H Yates P Cameron LA Barnes MR Gray IC Spurr NK Hurko O St Clair D 《Nature genetics》2001,28(2):128-129
The NOTCH4 gene was recently reported to be associated with schizophrenia based on TDT analysis of 80 British trios. The strongest evidence for association derived from two microsatellites. We genotyped both loci in a large sample of unrelated Scottish schizophrenics and controls, but failed to replicate the reported association, finding instead that each putative schizophrenia-associated allele had a somewhat lower frequency in schizophrenics than in controls. 相似文献
866.
A radiation hybrid map of mouse genes 总被引:13,自引:0,他引:13
Hudson TJ Church DM Greenaway S Nguyen H Cook A Steen RG Van Etten WJ Castle AB Strivens MA Trickett P Heuston C Davison C Southwell A Hardisty R Varela-Carver A Haynes AR Rodriguez-Tome P Doi H Ko MS Pontius J Schriml L Wagner L Maglott D Brown SD Lander ES Schuler G Denny P 《Nature genetics》2001,29(2):201-205
A comprehensive gene-based map of a genome is a powerful tool for genetic studies and is especially useful for the positional cloning and positional candidate approaches. The availability of gene maps for multiple organisms provides the foundation for detailed conserved-orthology maps showing the correspondence between conserved genomic segments. These maps make it possible to use cross-species information in gene hunts and shed light on the evolutionary forces that shape the genome. Here we report a radiation hybrid map of mouse genes, a combined project of the Whitehead Institute/Massachusetts Institute of Technology Center for Genome Research, the Medical Research Council UK Mouse Genome Centre, and the National Center for Biotechnology Information. The map contains 11,109 genes, screened against the T31 RH panel and positioned relative to a reference map containing 2,280 mouse genetic markers. It includes 3,658 genes homologous to the human genome sequence and provides a framework for overlaying the human genome sequence to the mouse and for sequencing the mouse genome. 相似文献
867.
868.
Grimm DR Colter MB Braunschweig M Alexander LJ Neame PJ Kim HK 《Cellular and molecular life sciences : CMLS》2001,58(1):148-159
Factor V is a plasma protein essential for blood coagulation. This protein is involved in activated protein C resistance,
the most common inherited thrombotic disorder known. We utilized the polymerase chain reaction to clone the porcine factor
V gene by generating overlapping clones amplified with primers chosen by comparison with known nucleotide sequences. The porcine
factor V cDNA contig encodes a predicted 2258-amino acid protein, making it the largest in comparison to the bovine, human,
and murine proteins. Porcine factor V has the highest level of homology with bovine factor V, but also has high levels of
conservation of important residues with all the species. Radiation hybrid mapping assigned the porcine factor V gene to chromosome
4. Three-dimensional models of factor V were generated and used to analyze membrane-binding sites in terms of conserved, and
therefore likely important residues.
Received 3 October 2000; revised 23 November 2000; accepted 6 December 2000 相似文献
869.
The electrical and optical properties of conjugated polymers have received considerable attention in the context of potentially low-cost replacements for conventional metals and inorganic semiconductors. Charge transport in these organic materials has been characterized in both the doped-metallic and the semiconducting state, but superconductivity has not hitherto been observed in these polymers. Here we report a distinct metal-insulator transition and metallic levels of conductivity in a polymer field-effect transistor. The active material is solution-cast regioregular poly(3-hexylthiophene), which forms relatively well ordered films owing to self-organization, and which yields a high charge carrier mobility (0.05-0.1 cm2 V(-1) s(-1)) at room temperature. At temperatures below approximately 2.35 K with sheet carrier densities exceeding 2.5 x 10(14) cm(-2), the polythiophene film becomes superconducting. The appearance of superconductivity seems to be closely related to the self-assembly properties of the polymer, as the introduction of additional disorder is found to suppress superconductivity. Our findings therefore demonstrate the feasibility of tuning the electrical properties of conjugated polymers over the largest range possible-from insulating to superconducting. 相似文献
870.