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161.
E. Brad Thompson Rheem D. Medh Feng Zhou Sylvette Ayala-Torres Naseem Ansari Weiping Zhang Betty H. Johnson 《The Journal of steroid biochemistry and molecular biology》1999,69(1-6)
In clones of the CEM human acute lyumphoblastic leukemic cell line, glucocorticoids, oxysterols and activators of the cAMP pathway acting synergistically with glucocorticoids, each can cause apoptotic cell death. Morphologically and kinetically, these deaths resemble one another. The kinetics are striking: in each case, after addition of the lethal compound(s), an interval of approximately 24 h follows, during which cell growth continues unabated. During this “prodromal” period, removal of the apoptotic agent leaves the cells fully viable. We hypothesize that a sequence of biochemical events occurs during the prodrome which eventually results in the triggering of the full apoptotic response as evidenced by the activation of caspases and DNA fragmentation. At some point, the process is irreversible and proceeds relatively rapidly to cell death. Suppression of c-Myc seems a universal early event evoked by each of these lethal compounds or combinations, and we conclude that the negative regulation of this proto-oncogene is an important aspect of the critical pre-apoptotic events in these cells. 相似文献
162.
UNC-11, a Caenorhabditis elegans AP180 Homologue, Regulates the Size and Protein Composition of Synaptic Vesicles 下载免费PDF全文
Michael L. Nonet Andrea M. Holgado Faraha Brewer Craig J. Serpe Betty A. Norbeck Julianne Holleran Liping Wei Erika Hartwieg Erik M. Jorgensen Aixa Alfonso 《Molecular biology of the cell》1999,10(7):2343-2360
The unc-11 gene of Caenorhabditis elegans encodes multiple isoforms of a protein homologous to the mammalian brain-specific clathrin-adaptor protein AP180. The UNC-11 protein is expressed at high levels in the nervous system and at lower levels in other tissues. In neurons, UNC-11 is enriched at presynaptic terminals but is also present in cell bodies. unc-11 mutants are defective in two aspects of synaptic vesicle biogenesis. First, the SNARE protein synaptobrevin is mislocalized, no longer being exclusively localized to synaptic vesicles. The reduction of synaptobrevin at synaptic vesicles is the probable cause of the reduced neurotransmitter release observed in these mutants. Second, unc-11 mutants accumulate large vesicles at synapses. We propose that the UNC-11 protein mediates two functions during synaptic vesicle biogenesis: it recruits synaptobrevin to synaptic vesicle membranes and it regulates the size of the budded vesicle during clathrin coat assembly. 相似文献
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Cottyn B Acher F Ramassamy B Alvey L Lepoivre M Frapart Y Stuehr D Mansuy D Boucher JL Vichard D 《Bioorganic & medicinal chemistry》2008,16(11):5962-5973
A series of new 7-monosubstituted and 3,7-disubstituted indazoles have been prepared and evaluated as inhibitors of nitric oxide synthases (NOS). 1H-indazole-7-carbonitrile (6) was found equipotent to 7-nitro-1H-indazole (1) and demonstrated preference for constitutive NOS over inducible NOS. By contrast, 1H-indazole-7-carboxamide (8) was slightly less potent but demonstrated a surprising selectivity for the neuronal NOS. Further substitution of 6 by a Br-atom at carbon-3 of the heterocycle enhanced 10-fold the inhibitory effects. Inhibition of NO formation by 6 appeared to be competitive versus both substrate and the cofactor (6R)-5,6,7,8-tetrahydro-l-biopterin (H(4)B). In close analogies with 1, compound 6 strongly inhibited the NADPH oxidase activity of nNOS and induced a spin state transition of the heme-Fe(III). Our results are explained with the help of the X-ray structures that identified key-features for binding of 1 at the active site of NOS. 相似文献
166.
Tropical hardwood hammocks, among the rarest and most threatened vegetative communities in the United States, occur throughout the 225-km Florida Keys archipelago as it extends toward the Caribbean from the southeast tip of peninsular Florida. Compounding their critical conservation status, tropical hardwood hammocks and the dynamics that support their peculiar species diversity in the region are poorly understood. The goal of this study was to explore the dynamics of the species compositional gradient of the hammocks along the Florida Keys, and to identify significant ecological units within the gradient. The primary data for this research were assembled from the Institute for Regional Conservation's floristic database of South Florida. We were able to extract presence/absence data for 295 species from comprehensive surveys of 23 study sites. Nonmetric multidimensional scaling was used to deconstruct the compositional trends into a reduced ordination space. Cluster analysis was subsequently used to identify discrete ecological units. Additionally, we used vector fitting to interpret the significant correlated ancillary variables. Our main results were three well-fitted nonmetric multidimensional scaling axes with three nonoverlapping ecological units. Of the ancillary variables, latitude, longitude, percent composition from biogeographical regions, richness, and area were correlated to the nonmetric multidimensional scaling results. These results increase our understanding of the community structure of the hammocks along the Florida Keys, and can contribute to increasing our ability to adequately protect and restore tropical hardwood hammocks and other similar tropical dry forest communities throughout the Caribbean. 相似文献
167.
Ethidium monoazide bromide (EMA) treatment of pure culture and environmental waters at low concentrations (1.0–7.5 μg/ml)
indicated effective enumeration of viable and viable but nonculturable Escherichia coli in pure cultures, creek waters, and secondary activated sludge effluent samples by quantitative polymerase chain reaction
(qPCR) amplification of the uidA and fliC gene targets at turbidity values <10 NTU. However, EMA treatment was not effective in primary clarifier and secondary trickling
filter effluents where turbidities were ≥10 NTU. In viable pure cultures, rapidly dividing and senescent cells were most affected
by increasing EMA concentrations. Amplification of heat-killed pure bacterial cultures decreased 4 to 6 logs depending on
EMA concentration and culture age. The greatest difference was observed in 5-h cultures using 7.5 μg/ml EMA. Turbidity (≥100
NTU) in environmental samples inhibited EMA effectiveness on viability discrimination. Enumeration of E. coli in certain wastewaters using EMA-qPCR was similar to culture suggesting that EMA treatment could be incorporated into qPCR
assays for the quantification of viable bacteria increasing assay time no more than 30 min. Our results indicate that EMA
can be used in routine qPCR assays, but optimum conditions for exposure must be identified for each sample type due to sample
matrix effects such as turbidity. 相似文献
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Frederic Dalle Betty Wchtler Coralie L'Ollivier Gudrun Holland Norbert Bannert Duncan Wilson Catherine Labrure Alain Bonnin Bernhard Hube 《Cellular microbiology》2010,12(2):248-271
The human pathogenic fungus Candida albicans can cause systemic infections by invading epithelial barriers to gain access to the bloodstream. One of the main reservoirs of C. albicans is the gastrointestinal tract and systemic infections predominantly originate from this niche. In this study, we used scanning electron and fluorescence microscopy, adhesion, invasion and damage assays, fungal mutants and a set of fungal and host cell inhibitors to investigate the interactions of C. albicans with oral epithelial cells and enterocytes. Our data demonstrate that adhesion, invasion and damage by C. albicans depend not only on fungal morphology and activity, but also on the epithelial cell type and the differentiation stage of the epithelial cells, indicating that epithelial cells differ in their susceptibility to the fungus. C. albicans can invade epithelial cells by induced endocytosis and/or active penetration. However, depending on the host cell faced by the fungus, these routes are exploited to a different extent. While invasion into oral cells occurs via both routes, invasion into intestinal cells occurs only via active penetration. 相似文献