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红腹锦鸡和白腹锦鸡卵壳的超微结构 总被引:16,自引:2,他引:16
本文报道了锦鸡属——白腹锦鸡和红腹锦鸡卵壳的气孔、外壳膜、锥体层、木栅层的超微结构。并对两者的卵壳进行了比较。 相似文献
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Ran Luo Xiongwei Wang Yuanxun Dong Lei Wang Chunlei Tian 《Journal of biomedical science》2014,21(1):25
Background
The pathogenesis of glioma is unclear. The disturbance of the apoptosis process plays a critical role in glioma growth. Factors regulating the apoptosis process are to be further understood. This study aims to investigate the role of protease activated receptor-2 (PAR2) in regulation the apoptosis process in glioma cells.Results
The results showed that U87 cells and human glioma tissue expressed PAR2. Exposure to tryptase, or the PAR2 active peptide, increased STAT3 phosphorylation in the radiated U87 cells, reduced U87 cell apoptosis, suppressed the expression of p53 in U87 cells.Conclusions
Activation of PAR2 can reduce the radiated U87 cell apoptosis via modulating the expression of p53. The results implicate that PAR2 may be a novel therapeutic target in the treatment of glioma. 相似文献68.
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Extracellular phosphatase can be produced by phytoplankton to utilize organic phosphorus under phosphorus (P) deficiency.
However, there is a controversy about its use as an indicator of P deficiency in natural phytoplankton community inferred
by such an “induction–repression” mechanism. Size-fractionation of alkaline phosphatase activity (APA), soluble reactive phosphorus
(SRP) concentration, algal density, and composition were determined in six Chinese shallow lakes ranking in gradient of trophic
status, where a positive relationship between SRP concentration and algal density was observed. Enzyme-labeled fluorescence
(ELF) method was used to localize phosphatase on cell membrane of algae. The so-called algal APA that associated with coarser
particle (>3.0 μm) accounted for the largest part of total APA. Within a lake with lower SRP concentration, the “induction–repression”
mechanism held true. Contrastingly, both algal and total APA were positively related to SRP concentration based on the data
across all study lakes with statistical significance, which may be explained firstly by algal composition. The lakes with
higher SRP concentration were dominated by diatoms and green algae, while they easily produced extracellular phosphatases
as evidenced by ELFA labeling. In parallel, the lakes with lower SRP concentration were dominated by cyanobacteria, while
it was never ELFA-positive; secondly, ELFA-positive dots or structures suggested that, in lakes with higher trophic status,
attached bacteria or heterotrophic microorganisms could substantially contribute to extracellular phosphatases for hydrolyzing
organophosphoric compounds but probably utilizing the organic moiety as an organic carbon source. This process simultaneously
produces inorganic P, leading to the co-occurrence of high phosphate concentration and APA. So, the contributor of APA are
complex, which may produce extracellular phosphatase species-specific or not exclusively for P nutrient and consequently make
it difficult to normalize APA with the exact biomass estimators. Therefore, it is not reasonable to use APA, normalized or
not, as a general indicator for describing P deficiency of phytoplankton in shallow lakes especially eutrophic ones. 相似文献
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