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排序方式: 共有213条查询结果,搜索用时 828 毫秒
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Tilburgs T Roelen DL van der Mast BJ de Groot-Swings GM Kleijburg C Scherjon SA Claas FH 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(8):5737-5745
During pregnancy, the maternal immune system has to tolerate the persistence of fetal alloantigens. Many mechanisms contribute to the prevention of a destructive immune response mediated by maternal alloreactive lymphocytes directed against the allogeneic fetus. Murine studies suggest that CD4(+)CD25(+) T cells provide mechanisms of specific immune tolerance to fetal alloantigens during pregnancy. Previous studies by our group demonstrate that a significantly higher percentage of activated T cells and CD4(+)CD25(bright) T cells are present in decidual tissue in comparison with maternal peripheral blood in human pregnancy. In this study, we examined the phenotypic and functional properties of CD4(+)CD25(bright) T cells derived from maternal peripheral blood and decidual tissue. Depletion of CD4(+)CD25(bright) T cells from maternal peripheral blood demonstrates regulation to third party umbilical cord blood cells comparable to nonpregnant controls, whereas the suppressive capacity to umbilical cord blood cells of her own child is absent. Furthermore, maternal peripheral blood shows a reduced percentage of CD4(+)CD25(bright)FOXP3(+) and CD4(+)CD25(bright)HLA-DR(+) cells compared with peripheral blood of nonpregnant controls. In contrast, decidual lymphocyte isolates contain high percentages of CD4(+)CD25(bright) T cells with a regulatory phenotype that is able to down-regulate fetus-specific and fetus-nonspecific immune responses. These data suggest a preferential recruitment of fetus-specific regulatory T cells from maternal peripheral blood to the fetal-maternal interface, where they may contribute to the local regulation of fetus-specific responses. 相似文献
34.
J Holms K Mast P Marcotte I Elmore J Li L Pease K Glaser D Morgan M Michaelides S Davidsen 《Bioorganic & medicinal chemistry letters》2001,11(22):2907-2910
Modification of the P(1)' substituent of macrocyclic matrix metalloproteinase (MMP) inhibitors provided compounds that are selective for inhibition of tumor necrosis factor-alpha converting enzyme (TACE) over MMP-1 and MMP-2. Several analogues potently inhibited the release of TNF-alpha in a THP-1 cellular assay. Compounds containing a trimethoxyphenyl group in the P(1)' substituent demonstrated TACE selectivity across several series of hydroxamate-based inhibitors. 相似文献
35.
Laurel Mast 《Bioethics》2020,34(3):264-271
Significant criticisms have been raised regarding the ethical and psychological basis of living wills. Various solutions to address these criticisms have been advanced, such as the use of surrogate decision makers alone or data science-driven algorithms. These proposals share a fundamental weakness: they focus on resolving the problems of living wills, and, in the process, lose sight of the underlying ethical principle of advance care planning, autonomy. By suggesting that the same sweeping solutions, without opportunities for choice, be applied to all, individual patients are treated as population-level groups—as a theoretical patient who represents a population, not the specific patient crafting his or her individualized future care plans. Instead, advance care planning can be improved through a multimodal approach that both mitigates cognitive biases and allows for customization of the decision-making process by allowing for the incorporation of a variety of methods of advance care planning. 相似文献
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Disturbance and climatic influences on age structure of ponderosa pine at the pine/grassland ecotone, Colorado Front Range 总被引:1,自引:0,他引:1
Abstract. In the Colorado Front Range, disturbances and climatic variation influence stand structure of ponderosa pine (Pinus ponderosa) along the lower timberline ecotone. Over the past 100 years there has been a shift to a greater density and extent of ponderosa pine at the forest-grassland boundaries. Ponderosa pine regeneration at lower timberline appears to be influenced by fires in the 1860s and decreased grazing pressure in the 1970s–1980s. Climatic variation may also have influenced age structure, even though analyses of age structure at a 10-year class scale prevented the detection of climatic influences occurring at a finer scale. These changes in disturbance regimes, possibly together with moister springs/early summers, created favourable conditions for the increase in density and extent of ponderosa pine at lower timberline ecotone. 相似文献
38.
Margaret L. Rodgers U. Sandy Tretbar Alexander Dehaven Amir A. Alwan George Luo Hannah M. Mast Aaron A. Hoskins 《RNA (New York, N.Y.)》2016,22(2):225-236
The spliceosome undergoes dramatic changes in both small nuclear RNA (snRNA) composition and structure during assembly and pre-mRNA splicing. It has been previously proposed that the U2 snRNA adopts two conformations within the stem II region: stem IIa or stem IIc. Dynamic rearrangement of stem IIa into IIc and vice versa is necessary for proper progression of the spliceosome through assembly and catalysis. How this conformational transition is regulated is unclear; although, proteins such as Cus2p and the helicase Prp5p have been implicated in this process. We have used single-molecule Förster resonance energy transfer (smFRET) to study U2 stem II toggling between stem IIa and IIc. Structural interconversion of the RNA was spontaneous and did not require the presence of a helicase; however, both Mg2+ and Cus2p promote formation of stem IIa. Destabilization of stem IIa by a G53A mutation in the RNA promotes stem IIc formation and inhibits conformational switching of the RNA by both Mg2+ and Cus2p. Transitioning to stem IIa can be restored using Cus2p mutations that suppress G53A phenotypes in vivo. We propose that during spliceosome assembly, Cus2p and Mg2+ may work together to promote stem IIa formation. During catalysis the spliceosome could then toggle stem II with the aid of Mg2+ or with the use of functionally equivalent protein interactions. As noted in previous studies, the Mg2+ toggling we observe parallels previous observations of U2/U6 and Prp8p RNase H domain Mg2+-dependent conformational changes. Together these data suggest that multiple components of the spliceosome may have evolved to switch between conformations corresponding to open or closed active sites with the aid of metal and protein cofactors. 相似文献
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Lactic acid bacteria as reducing and capping agent for the fast and efficient production of silver nanoparticles 总被引:1,自引:0,他引:1
Liesje Sintubin Wim De Windt Jan Dick Jan Mast David van der Ha Willy Verstraete Nico Boon 《Applied microbiology and biotechnology》2009,84(4):741-749
There is a growing demand for silver-based biocides, including both ionic silver forms and metallic nanosilver. The use of
metallic nanosilver, typically chemically produced, faces challenges including particle agglomeration, high costs, and upscaling
difficulties . Additionally, there exists a need for the development of a more eco-friendly production of nanosilver. In this
study, Gram-positive and Gram-negative bacteria were utilized in the non-enzymatic production of silver nanoparticles via
the interaction of silver ions and organic compounds present on the bacterial cell. Only lactic acid bacteria, Lactobacillus spp., Pediococcus pentosaceus, Enterococcus faecium, and Lactococcus garvieae, were able to reduce silver. The nanoparticles of the five best producing Lactobacillus spp. were examined more into detail with transmission electron microscopy. Particle localization inside the cell, the mean
particle size, and size distribution were species dependent, with Lactobacillus fermentum having the smallest mean particle size of 11.2 nm, the most narrow size distribution, and most nanoparticles associated with
the outside of the cells. Furthermore, influence of pH on the reduction process was investigated. With increasing pH, silver
recovery increased as well as the reduction rate as indicated by UV–VIS analyses. This study demonstrated that Lactobacillus spp. can be used for a rapid and efficient production of silver nanoparticles. 相似文献