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131.
132.
F D Finkelman D K Goroff M Fultz S C Morris J M Holmes J J Mond 《Journal of immunology (Baltimore, Md. : 1950)》1990,145(11):3562-3569
Injection of BALB/c mice with an affinity-purified goat antibody to mouse IgD (GaM delta) stimulates T cell-independent B cell activation as well as later T cell activation. Activated T cells then induce polyclonal differentiation of B cells into IgG1-secreting cells, which results in an approximately 100-fold increase in serum IgG1 level. It is not known whether the same B cells that are initially activated by GaM delta are the progenitors of the IgG1-secreting cells. To investigate this issue a system was developed in which CB20 mice, which are congenic to BALB/c mice but express Ig of the beta allotype rather than the BALB/c alpha allotype, were injected with GaM delta and simultaneously or subsequently also received BALB/c B cells. The IgG1 response generated by the donor BALB/c B cells was quantitated by an assay specific for IgG1 of the alpha allotype. Our experiments with this system indicate that: 1) BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta generate a much larger IgG1 response than do BALB/c B cells transferred simultaneously with GaM delta antibody; 2) B cells that express membrane IgD generate the great majority of this response; 3) differences in the magnitudes of the responses of BALB/c B cells transferred at different times after CB20 mice were injected with GaM delta antibody cannot be explained by differences in homing of the donor B cells to the host spleen or by short survival of donor BALB/c B cells after their transfer; and 4) the response made by donor BALB/c B cells transferred 2 days after CB20 mice were injected with GaM delta is proportionate to donor cell representation in the host spleen 1 day after their transfer, whereas the response made by donor cells transferred simultaneously with GaM delta is disproportionately small. These observations suggest that most of the IgG1 antibody made by GaM delta-injected mice is generated by newly produced, mIgD+ B cells that appear approximately 2 days after GaM delta injection, rather than by those B cells that are present in the spleen at the time of GaM delta injection, and support the view that signals that induce B cell secretion of Ig require an interaction with at least partially activated Th cells. 相似文献
133.
Structure and assembly of turnip crinkle virus. VI. Identification of coat protein binding sites on the RNA 总被引:7,自引:0,他引:7
Structural studies of turnip crinkle virus have been extended to include the identification of high-affinity coat protein binding sites on the RNA genome. Virus was dissociated at elevated pH and ionic strength, and a ribonucleoprotein complex (rp-complex) was isolated by chromatography on Sephacryl S-200. Genomic RNA fragments in the rp-complex, resistant to RNase A and RNase T1 digestion and associated with tightly bound coat protein subunits, were isolated using coat-protein-specific antibodies. The identity of the protected fragments was determined by direct RNA sequencing. These approaches allowed us to study the specific RNA-protein interactions in the rp-complex obtained from dissociated virus particles. The location of one protected fragment downstream from the amber terminator codon in the first and largest of the three viral open reading frames suggests that the coat protein may play a role in the regulation of the expression of the polymerase gene. We have also identified an additional cluster of T1-protected fragments in the region of the coat protein gene that may represent further high-affinity sites involved in assembly recognition. 相似文献
134.
Analysis of Chlamydomonas reinhardtii histones and chromatin 总被引:3,自引:0,他引:3
Chromatin spreads made from isolated nuclei of the unicellular green alga Chlamydomonas reinhardtii show the beaded fibers typical of eukaryotic polynucleosomes. Micrococcal nuclease digestions confirmed the presence of nucleosomes with a repeat length of 189 base pairs, essentially the same as typical mammalian cells. Basic nuclear proteins extracted from isolated nuclei or chromatin with 1 M calcium chloride and 0.3 M hydrochloric acid are resolved into seven major components by electrophoresis in the presence of sodium dodecyl sulfate (SDS). These seven components were subjected to qualitative peptide mapping with V8 protease on SDS gels for comparison with the major histone components of calf thymus. Finally, the C. reinhardtii basic nuclear proteins were fractionated by reversed phase high performance liquid chromatography and their amino acid composition determined. From these studies, we conclude that C. reinhardtii has a full complement of the five histones with properties very similar to those of both higher animals and higher plants. 相似文献
135.
136.
Chromosomal localization of ARSB,the gene for human N-acetylgalactosamine-4-sulphatase 总被引:2,自引:0,他引:2
Tom Litjens Elizabeth G. Baker Kerri R. Beckmann C. Phillip Morris John J. Hopwood David F. Callen 《Human genetics》1989,82(1):67-68
Summary A deficiency of N-acetylgalactosamine-4-sulphatase (G4S, gene symbol ARSB), results in the accumulation of undegraded substrate and the lysosomal storage disorder, Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI). In situ hybridization using an 3H-labelled human G4S genomic DNA fragment to human metaphase chromosomes localized ARSB to chromosome 5q13–5q14. This location is consistent with, an refines, previous chromosomal assignments based on the expression of human G4S in somatic cell hybrids. 相似文献
137.
J C Randall D C Morris S Zeiger K Masuhara T Tsuda H C Anderson 《The journal of histochemistry and cytochemistry》1989,37(7):1069-1074
The presence and activity of alkaline phosphatase in SAOS-2 and TE-85 human osteosarcoma cells grown in culture were examined at the ultrastructural level. A monoclonal antibody raised against purified human bone osteosarcoma alkaline phosphatase was used to localize the enzyme in cultures of the osteosarcoma cells. Similar cultures were analyzed for alkaline phosphatase activity using an enzyme cytochemical method with cerium as the capture agent. Alkaline phosphatase was immunolocalized at the light microscopic level in an osteogenic sarcoma and ultrastructurally on the SAOS-2 cell membrane and the enclosing membrane of extracellular vesicular structures close to the cells. In contrast, the TE-85 cells were characterized by the absence of all but a few traces of immunolabeling at the cell surface. Enzyme cytochemical studies revealed strong alkaline phosphatase activity on the outer surface of the SAOS-2 cell membrane. Much lower enzyme activity was observed in the TE-85 cells. The results support biochemical data from previous studies and confirm that SAOS-2 cells have a significantly greater concentration of alkaline phosphatase at the plasma membrane. 相似文献
138.
Rapid recovery of Echinococcus granulosus following 'successful' albendazole therapy in a gerbil model 总被引:3,自引:0,他引:3
Peritoneal Echinococcus granulosus in gerbils was treated with albendazole. Both early and late infections were studied; response to albendazole therapy and the ability of the parasite to recover after treatment was found to depend on dose and length of therapy. Even after treatment at 50 mg/kg for 2 months late infections retained the ability to recover over 3 months. 相似文献
139.
Transfusion induces blood donor-specific suppressor cells 总被引:5,自引:0,他引:5
Transfusion with blood from the organ donor before transplantation can prolong the survival of renal allografts in the rat. To determine if the beneficial effect of preoperative blood transfusion was due to the generation of donor-specific suppressor cells, in vivo and in vitro adoptive transfer experiments were performed. Lymphoid cells were harvested from transfused and untreated rats. These cells were then either (1) transferred to lightly irradiated (200 R) syngeneic hosts which were subsequently challenged with a kidney allograft (in vivo assay) or (2) titrated as regulator cells into naive unidirectional MLC such that the regulator and responder populations were syngeneic. In the LEW-RT1 to DA-RT1av1 strain combination, the adoptive transfer of thoracic duct lymph (TDL) or lymph node (LN) cells (5 x 10(7) to 7.5 x 10(7) cells) from DA animals transfused with LEW blood, 7 days previously into syngeneic (DA), lightly irradiated (200 R) hosts resulted in the indefinite survival of LEW kidney allografts. The phenomenon was blood donor-specific and dose-dependent. In contrast the adoptive transfer of spleen cells (10(7) to 10(8] from blood transfused hosts 7 days after transfusion had no effect on renal allograft survival. In vitro the addition of LN or TDL regulator cells, harvested from DA rats transfused with LEW blood, to a unidirectional MLC (DA responders, LEW stimulators) resulted in a significant depression of the proliferative response when compared with the proliferation of these same cells without the addition of these regulator cells or with the addition of LN or TDL regulator cells from a DA rat transfused with third party (PVG-RT1c) blood. The depression of the proliferative response observed in vitro, was blood donor specific. When LN or TDL regulator cells from a DA rat transfused with PVG-RT1c blood were added to a unidirectional MLC between DA responders and PVG stimulators, a significant depression in the proliferative response was observed. These in vitro findings were confirmed in two other strain combinations (LEW-PVG, and DA-PVG). Thus a single blood transfusion results in the induction of donor-specific suppressor cells detectable both in vivo and in vitro 7 days after transfusion in some but not all lymphoid compartments. 相似文献
140.
Immunoaffinity techniques using columns of immobilized antibodies raised against zeatin riboside and isopentenyladenosine were found to be effective in isolating cytoklnins from vegetative, female, and male buds of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The purified cytokinins were separated by reverse phase high performance liquid chromatography and analyzed by radioimmunoassay. Confirmation of cytokinin identities was by gas chromatography-mass spectrometry. Immediately prior to bud burst, all bud types contained three major cytokinins: isopentenyladenosine, zeatin riboside, and a hexose conjugate of zeatin riboside (not zeatin riboside O-glucoside). Zeatin-type cytokinins were present in relatively high concentration in vegetative and female buds. In male buds, however, relatively high levels of isopentenyladenosine were found together with low levels of zeatin-type cytokinins. 相似文献