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31.
Signal transduction and cellular radiation responses 总被引:13,自引:0,他引:13
32.
Zhuo Wang Stephanie Brandt Alexandra Medeiros Soujuan Wang Hao Wu Alexander Dent C. Henrique Serezani 《PloS one》2015,10(2)
Macrophages dictate both initiation and resolution of inflammation. During acute inflammation classically activated macrophages (M1) predominate, and during the resolution phase alternative macrophages (M2) are dominant. The molecular mechanisms involved in macrophage polarization are understudied. MicroRNAs are differentially expressed in M1 and M2 macrophages that influence macrophage polarization. We identified a role of miR-21 in macrophage polarization, and found that cross-talk between miR-21 and the lipid mediator prostaglandin E2 (PGE2) is a determining factor in macrophage polarization. miR-21 inhibition impairs expression of M2 signature genes but not M1 genes. PGE2 and its downstream effectors PKA and Epac inhibit miR-21 expression and enhance expression of M2 genes, and this effect is more pronounced in miR-21-/- cells. Among potential targets involved in macrophage polarization, we found that STAT3 and SOCS1 were enhanced in miR-21-/- cells and further enhanced by PGE2. We found that STAT3 was a direct target of miR-21 in macrophages. Silencing the STAT3 gene abolished PGE2-mediated expression of M2 genes in miR-21-/- macrophages. These data shed light on the molecular brakes involved in homeostatic macrophage polarization and suggest new therapeutic strategies to prevent inflammatory responses. 相似文献
33.
34.
Dent A. Earl Kristina D. Louie Carolyne Bardeleben Camm C. Swift David K. Jacobs 《Conservation Genetics》2010,11(1):103-114
The federally endangered tidewater goby, Eucyclogobius newberryi, is the most locally differentiated vertebrate with marine dispersal on the California Coast. It inhabits seasonally closed
estuaries along the California coast; a habitat heavily impacted by anthropogenic filling and artificial opening, and exhibits
varied metapopulation behavior as a consequence of hydrologic variation and anthropogenic impact. We describe 19 taxon-specific
microsatellite loci, and assess genetic variation across the taxon range relative to genetic subdivision. A highly divergent
southern clade, with reduced genetic variation, now confined to Northern San Diego County, appears to merit status as a separate
species. The mid-coast is subdivided into regional groups with overall similarity to, and minor differences from previous
mitochondrial sequence based clades. The northernmost region, although locally differentiated, forms a star phylogeny with
limited geographic structure which we attribute to dispersal during Pleistocene/Holocene sea-level rise followed by increasing
isolation during the Holocene. Bottleneck/founder events are evident in some habitats thought to have experienced (anthropogenic)
extirpation. Further work with more, and larger, samples will be required to assess local and regional differences. Analytical
methods employed include Analysis of Molecular Variance (AMOVA), Neighbor-Joining, Bayesian/STRUCTURE analysis and Principle
Components Analysis (PCA). 相似文献
35.
Arthur R. Grossman Steven J. Karpowicz Mark Heinnickel David Dewez Blaise Hamel Rachel Dent Krishna K. Niyogi Xenie Johnson Jean Alric Francis-André Wollman Huiying Li Sabeeha S. Merchant 《Photosynthesis research》2010,106(1-2):3-17
Chlamydomonas reinhardtii, a unicellular green alga, has been exploited as a reference organism for identifying proteins and activities associated with the photosynthetic apparatus and the functioning of chloroplasts. Recently, the full genome sequence of Chlamydomonas was generated and a set of gene models, representing all genes on the genome, was developed. Using these gene models, and gene models developed for the genomes of other organisms, a phylogenomic, comparative analysis was performed to identify proteins encoded on the Chlamydomonas genome which were likely involved in chloroplast functions (or specifically associated with the green algal lineage); this set of proteins has been designated the GreenCut. Further analyses of those GreenCut proteins with uncharacterized functions and the generation of mutant strains aberrant for these proteins are beginning to unmask new layers of functionality/regulation that are integrated into the workings of the photosynthetic apparatus. 相似文献
36.
The fungal cyanide hydratases form a functionally specialized subset of the nitrilases which catalyze the hydrolysis of cyanide
to formamide with high specificity. These hold great promise for the bioremediation of cyanide wastes. The low resolution
(3.0 nm) three-dimensional reconstruction of negatively stained recombinant cyanide hydratase fibers from the saprophytic
fungus Neurospora crassa by iterative helical real space reconstruction reveals that enzyme fibers display left-handed D1 S5.4 symmetry with a helical rise of 1.36 nm. This arrangement differs from previously characterized microbial nitrilases which
demonstrate a structure built along similar principles but with a reduced helical twist. The cyanide hydratase assembly is
stabilized by two dyadic interactions between dimers across the one-start helical groove. Docking of a homology-derived atomic
model into the experimentally determined negative stain envelope suggests the location of charged residues which may form
salt bridges and stabilize the helix. 相似文献
37.
Evolutionary dynamics of the kinetochore network in eukaryotes as revealed by comparative genomics 下载免费PDF全文
Jolien JE van Hooff Eelco Tromer Leny M van Wijk Berend Snel Geert JPL Kops 《EMBO reports》2017,18(9):1559-1571
During eukaryotic cell division, the sister chromatids of duplicated chromosomes are pulled apart by microtubules, which connect via kinetochores. The kinetochore is a multiprotein structure that links centromeres to microtubules, and that emits molecular signals in order to safeguard the equal distribution of duplicated chromosomes over daughter cells. Although microtubule‐mediated chromosome segregation is evolutionary conserved, kinetochore compositions seem to have diverged. To systematically inventory kinetochore diversity and to reconstruct its evolution, we determined orthologs of 70 kinetochore proteins in 90 phylogenetically diverse eukaryotes. The resulting ortholog sets imply that the last eukaryotic common ancestor (LECA) possessed a complex kinetochore and highlight that current‐day kinetochores differ substantially. These kinetochores diverged through gene loss, duplication, and, less frequently, invention and displacement. Various kinetochore components co‐evolved with one another, albeit in different manners. These co‐evolutionary patterns improve our understanding of kinetochore function and evolution, which we illustrated with the RZZ complex, TRIP13, the MCC, and some nuclear pore proteins. The extensive diversity of kinetochore compositions in eukaryotes poses numerous questions regarding evolutionary flexibility of essential cellular functions. 相似文献
38.
Radioligand binding of antagonists of platelet-activating factor to intact human platelets 总被引:1,自引:0,他引:1
Two new antagonists of platelet-activating factor (PAF), the pyrrolothiazole derivative 52770 RP and the triazolodiazepine WEB 2086, have been studied as radioligands in intact human platelets. [3H]52770 RP and [3H]WEB 2086 bound specifically to high-affinity sites with dissociation constants (Kd) of 14.8 and 6.1 nM, respectively. The maximal number of sites for [3H]52770 RP binding was approx. 15-fold higher than for [3H]PAF and [3H]WEB 2086. In addition, C16-PAF, lyso-PAF, WEB 2086 and 52770 RP had Ki values which were nearly identical for both [3H]PAF and [3H]WEB 2086, whereas only 52770 RP competed for [3H]52770 RP-binding sites. These results demonstrate that in human platelets the sites of [3H]WEB 2086 binding are identical to [3H]PAF-binding sites, whereas those of [3H]52770 RP are not. [3H]WEB 2086 appears, therefore, to be a suitable antagonist radioligand for labelling PAF receptors. 相似文献
39.
Clones of human ribosomal DNA containing the complete 18 S-rRNA and 28 S-rRNA genes. Characterization, a detailed map of the human ribosomal transcription unit and diversity among clones. 总被引:12,自引:1,他引:12 下载免费PDF全文
B E Maden C L Dent T E Farrell J Garde F S McCallum J A Wakeman 《The Biochemical journal》1987,246(2):519-527
40.
Oxygenic photosynthesis by algae and plants supports much of life on Earth. Several model organisms are used to study this vital process, but the unicellular green alga Chlamydomonas reinhardtii offers significant advantages for the genetic dissection of photosynthesis. Recent experiments with Chlamydomonas have substantially advanced our understanding of several aspects of photosynthesis, including chloroplast biogenesis, structure-function relationships in photosynthetic complexes, and environmental regulation. Chlamydomonas is therefore the organism of choice for elucidating detailed functions of the hundreds of genes involved in plant photosynthesis. 相似文献