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71.
72.
73.
Phorbol ester-stimulated superoxide production by murine bone marrow-derived macrophages requires preexposure to cytokines 总被引:2,自引:0,他引:2
Murine resident peritoneal macrophages (RPM) generate superoxide (O2-) in response to stimulation with PMA or zymosan. Murine bone marrow-derived macrophages (BMM) generate O2- in response to zymosan but not PMA. However, the ability to generate O2- in response to PMA could be induced in BMM by pre-exposing the cells to certain cytokines, including granulocyte-macrophage CSF (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), IFN-gamma, and, to a lesser extent, IL-1 alpha. Bacterial LPS also induced the ability to respond to PMA. These same agents were also shown to prime RPM for enhanced PMA-induced respiratory burst. In contrast to GM-CSF, CSF-1 did not enhance the ability of BMM or RPM to generate O2- in response to PMA. Pretreatment with GM-CSF or TNF-alpha did not significantly affect the zymosan-induced release of O2- by BMM. These results suggest that unprimed BMM have a deficiency in the PMA-dependent signaling pathway that is corrected by exposure to selected cytokines. The results also raise the possibility that the basal ability of tissue macrophages to generate a respiratory burst in response to PMA may be a reflection of in vivo exposure to cytokines. 相似文献
74.
F Velge-Roussel C Verwaerde J M Grzych A Auriault A Capron 《Journal of immunology (Baltimore, Md. : 1950)》1989,142(7):2527-2532
A rat IgE mAb specific for larval Ag (26 kDa, 56 kDa) has been shown to protect rats against Schistosoma mansoni infection. Immunizations of Lou/M rats performed with this IgE (Ab1) induced the production of antiidiotypic antibodies (Ab2). Moreover, after this Ab2 production, anti-antiidiotypic antibodies (Ab3) were revealed. The screening of Ab3 isotypes showed the presence of IgG Ab3 and more interestingly of IgE Ab3, i.e., the same isotype as Ab1. These IgE and IgG antibodies recognized predominantly the 26-kDa Ag and were cytotoxic for schistosomula in the presence of platelets for IgE Ab3 and eosinophils for IgG Ab3. Both IgE and IgG Ab3 conferred by passive transfer protective immunity to infected rats (up to 50%). Thus the immunization with an IgE mAb led in part to the production of Ab3 of the same isotype as Ab1. In conclusion, these results suggest that the isotype selection of the antibodies of the third generation (Ab3) might be influenced by the Ab1. The respective role of the idiotope and isotype of Ab1 in isotype regulation is discussed. 相似文献
75.
Serum samples of Meishan (13 animals) and Meishan x Wild Boar crosses (361 animals) were analysed by means of two-dimensional electrophoresis. Some new variants in protease inhibitor systems PO1A, PO1B and PI2 are reported. 相似文献
76.
S. Kleinle U. Wiesmann A. Superti-Furga S. Krähenbühl E. Boltshauser J. Reichen S. Liechti-Gallati 《Human genetics》1997,100(5-6):643-650
We used a strategy based on long PCR (polymerase chain reaction) for detection and characterization of mitochondrial DNA (mtDNA)
rearrangements in two patients with clinical signs suggesting Pearson syndrome and Kearns-Sayre syndrome (KSS), respectively,
and one patient with myopathic symptoms of unidentified origin. Mitochondrial DNA rearrangements were detected by amplification
of the complete mitochondrial genome (16.6 kb) using long PCR with primers located in essential regions of the mitochondrial
genome and quantified by three-primer PCR. Long PCR with deletion-specific primers was used for identification and quantitative
estimation of the different forms of rearranged molecules, such as deletions and duplications. We detected significant amounts
of a common 7.4-kb deletion flanked by a 12-bp direct repeat in all tissues tested from the patient with Pearson syndrome.
In skeletal muscle from the patient with clinical signs of KSS we found significant amounts of a novel 3.7-kb rearrangement
flanked by a 4-bp inverted repeat that was present in the form of deletions as well as duplications. In the patient suffering
from myopathic symptoms of unidentified origin we did not detect rearranged mtDNA in blood but found low levels of two rearranged
mtDNA populations in skeletal muscle, a previously described 7-kb deletion flanked by a 7-bp direct repeat and a novel 6.6-kb
deletion with no repeat. These two populations, however, were unlikely to be the cause of the myopathic symptoms as they were
present at low levels (10–40 ppm). Using a strategy based on screening with long PCR we were able to detect and characterize
high as well as low levels of mtDNA rearrangements in three patients.
Received: 10 March 1997 / Accepted: 20 May 1997 相似文献
77.
Norma L. Pucheu Norma L. Kerber Emilio A. Rivas Néstor Cortez Augusto F. Garcia 《Current microbiology》1997,34(3):155-161
Membranes from in vivo labeled cells of Rhodobacter
capsulatus U43[pTX35] grown photosynthetically carried 60% of
the [32P]-Pi in the “heavy” fraction (HM) after
sucrose gradient sedimentation. Metal-chelating chromatography of either
“heavy” or “light” (LM) membrane fractions rendered
similar Bchl-protein complex profiles after octyl-glucoside treatment,
including most of the radioactivity in the same corresponding elution
fraction (F II). Similar labeling distribution of pigment-protein complexes
was obtained for membranes of dark-grown cells induced by lowering oxygen
tension. Fractions derived from HM showed highly labeled LHIα, whereas the
same complex from LM was essentially [32P]-Pi-free, as revealed
by SDS-PAGE followed by autoradiography. Phospholipid analysis showed a
similar pattern for membranes isolated from cells photosynthetically or
semiaerobically grown, being the most abundant: phosphatidylglycerol,
phosphatidylethanolamine, cardiolipin, and phosphatidylcholine. Part of the
phospholipids from HM comigrated with LHIα during SDS-PAGE and dissociated
from the complexes only after solvent extraction and hydrophobic
chromatography. However, a small amount remained always attached to LHIα,
indicating an unusual strong interaction. These results suggest the existence
of two operationally defined membrane regions carrying LHIα complexes
differing in phosphorylation status and protein-phospholipid interaction.
Received: 10 August 1996 / Accepted: 10 September 1996 相似文献
78.
A. Ugolini B. Tiribilli C. Castellini 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,182(1):43-50
Experiments on compass orientation under artificial light were conducted with adult individuals of Talitrus saltator. The aim was to reproduce in the laboratory an orientation based on the sun compass corresponding to that recorded in conditions
of the true sun and sky. This was obtained by the creation within an opaque Plexiglas dome of a scenario that permitted variation
of the brightness of the artificial sky and sun. The results show that it is possible to obtain sun compass orientation corresponding
to the natural situation even in an artificial environment. It can be concluded that sandhoppers identify an artificial light
source as the sun if the artificial sky is also illuminated and if the intensities of the artificial sun and sky exceed certain
threshold values (1.13 and 10 μW cm−2, respectively). The results of other experiments under the natural blue sky with an artificial sun and with the real sun
attenuated are discussed.
Accepted: 23 May 1997 相似文献
79.
80.
Spectrophotometric quantification of lactic bacteria in alginate and control of cell release with chitosan coating 总被引:3,自引:0,他引:3
Y. Zhou E. Martins A. Groboillot C. P. Champagne & R. J. Neufeld 《Journal of applied microbiology》1998,84(3):342-348
Lactococcus lactis ssp. cremoris was entrapped within a Ca-alginate matrix, and an in situ spectrophotometric method for monitoring cell population in calcium alginate beads described. The intracapsular cell population can be estimated by measuring the optical density of beads containing cells, using cell-free beads as reference, or by measuring absorbance of a liquified bead suspension. Alginate beads, and beads coated with chitosan type I, II, and I and II mixtures, were examined for cell release. Lower viscosity chitosan (type I) coatings reduced cell release by a factor of 100 from105 cfu ml−1 to 103 cfu ml−1 after 6 h of fermentation. Reuse of chitosan I coated alginate beads also showed a reduction in cell release by a factor of 100. Cell loading and initial cell growth within the beads greatly affected cell release. Reducing the initial cell release would lower the overall levels of cell release throughout the fermentation. Compared to non-immobilized cultures, a 20–40% reduction in the lactic acid production rate was observed for alginate beads and chitosan I coated alginate beads, respectively. This reduction can be compensated for by increasing the intracapsular cell loading during immobilization, or before the onset of fermentation. 相似文献