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991.
Namhee Kim Prem K. Goel Madalina E. Tivarus Ashleigh Hillier David Q. Beversdorf 《PloS one》2010,5(8)
L-dopa, which is a precursor for dopamine, acts to amplify strong signals, and dampen weak signals as suggested by previous studies. The effect of L-dopa has been demonstrated in language studies, suggesting restriction of the semantic network. In this study, we aimed to examine the effect of L-dopa on language processing with fMRI using Independent Component Analysis (ICA). Two types of language tasks (phonological and semantic categorization tasks) were tested under two drug conditions (placebo and L-dopa) in 16 healthy subjects. Probabilistic ICA (PICA), part of FSL, was implemented to generate Independent Components (IC) for each subject for the four conditions and the ICs were classified into task-relevant source groups by a correlation threshold criterion. Our key findings include: (i) The highly task-relevant brain regions including the Left Inferior Frontal Gyrus (LIFG), Left Fusiform Gyrus (LFUS), Left Parietal lobe (LPAR) and Superior Temporal Gyrus (STG) were activated with both L-dopa and placebo for both tasks, and (ii) as compared to placebo, L-dopa was associated with increased activity in posterior regions, including the superior temporal area (BA 22), and decreased activity in the thalamus (pulvinar) and inferior frontal gyrus (BA 11/47) for both tasks. These results raise the possibility that L-dopa may exert an indirect effect on posterior regions mediated by the thalamus (pulvinar). 相似文献
992.
A universal reagent 1-O-(4,4'-dimethoxytrityl)-6-aminohexanol (DTAH) is described for the estimation of surface-bound functionalities (epoxy, aldehyde, and carboxyl) required for preparation of oligonucleotide arrays (biochips). The method involves the reaction of universal reagent DTAH with surface-bound functionality under microwaves for 10 min, followed by washings to remove the excess reagent. In the subsequent step, a weighed amount of DTAH-treated surface is exposed to acid to liberate 4,4'-dimethoxytrityl cation, which is measured at 505 nm to determine the functional group loading on the surface. 相似文献
993.
Prosenjit Sen Sanghamitra Sahoo Usha R. Pendurthi L. Vijaya Mohan Rao 《The Journal of biological chemistry》2010,285(26):20410-20420
Zinc is an essential trace element for human nutrition and is critical to the structure, stability, and function of many proteins. Zinc ions were shown to enhance activation of the intrinsic pathway of coagulation but down-regulate the extrinsic pathway of coagulation. The protein C pathway plays a key role in blood coagulation and inflammation. At present there is no information on whether zinc modulates the protein C pathway. In the present study we found that Zn2+ enhanced the binding of protein C/activated protein C (APC) to endothelial cell protein C receptor (EPCR) on endothelial cells. Binding kinetics revealed that Zn2+ increased the binding affinities of protein C/APC to EPCR. Equilibrium dialysis with 65Zn2+ revealed that Zn2+ bound to the Gla domain as well as sites outside of the Gla domain of protein C/APC. Intrinsic fluorescence measurements suggested that Zn2+ binding induces conformational changes in protein C/APC. Zn2+ binding to APC inhibited the amidolytic activity of APC, but the inhibition was reversed by Ca2+. Zn2+ increased the rate of APC generation on endothelial cells in the presence of physiological concentrations of Ca2+ but did not further enhance increased APC generation obtained in the presence of physiological concentrations of Mg2+ with Ca2+. Zn2+ had no effect on the anticoagulant activity of APC. Zn2+ enhanced APC-mediated activation of protease activated receptor 1 and p44/42 MAPK. Overall, our data show that Zn2+ binds to protein C/APC, which results in conformational changes in protein C/APC that favor their binding to EPCR. 相似文献
994.
Bradham CA Foltz KR Beane WS Arnone MI Rizzo F Coffman JA Mushegian A Goel M Morales J Geneviere AM Lapraz F Robertson AJ Kelkar H Loza-Coll M Townley IK Raisch M Roux MM Lepage T Gache C McClay DR Manning G 《Developmental biology》2006,300(1):180-193
This paper reports a preliminary in silico analysis of the sea urchin kinome. The predicted protein kinases in the sea urchin genome were identified, annotated and classified, according to both function and kinase domain taxonomy. The results show that the sea urchin kinome, consisting of 353 protein kinases, is closer to the Drosophila kinome (239) than the human kinome (518) with respect to total kinase number. However, the diversity of sea urchin kinases is surprisingly similar to humans, since the urchin kinome is missing only 4 of 186 human subfamilies, while Drosophila lacks 24. Thus, the sea urchin kinome combines the simplicity of a non-duplicated genome with the diversity of function and signaling previously considered to be vertebrate-specific. More than half of the sea urchin kinases are involved with signal transduction, and approximately 88% of the signaling kinases are expressed in the developing embryo. These results support the strength of this nonchordate deuterostome as a pivotal developmental and evolutionary model organism. 相似文献
995.
The genome sequence of the purple sea urchin Strongylocentrotus purpuratus recently became available. We report the results of functional annotation and initial analysis of more than 2300 proteins predicted to be involved in metabolite transport and enzymatic conversion in sea urchin. The comparison of various reconstructed biosynthetic and catabolic pathways in sea urchin to those known in other genomes suggests the overall similarity of the sea urchin metabolism to that of the vertebrates, with relatively small but non-trivial differences from both vertebrates and protostomes. There are several examples of two parallel, non-orthologous solutions for the same molecular function in sea urchin, in contrast with the other completely sequenced metazoans that tend to contain just one version of the same function. There are also genes that appear to be close phylogenetic neighbors of plant or bacterial homologs, as opposed to homologs in other Metazoa. The evolutionary and functional significance of these variations is discussed. 相似文献
996.
A. K. Goel A. K. Tamrakar V. Nema D. V. Kamboj L. Singh 《World journal of microbiology & biotechnology》2005,21(6-7):973-976
Summary Environmental monitoring is important to enable effective resource management and public health protection as well as rapid
and accurate identification of Vibrio cholerae in drinking-water sources. Traditional methods employed in identification are laborious, time-consuming and practically not
viable for screening of a large number of samples. In this study, a direct cell duplex PCR assay for the detection of viable
toxigenic V. cholerae in environmental water samples was developed. In the PCR assay, two gene sequences were amplified together, one of outer membrane
protein (ompW), which is species-specific and another of cholera toxin (ctxAB). The detection limit of duplex PCR was 5 × 104 V. cholerae/reaction. Different environmental water samples were artificially spiked with V. cholerae O1 cells and filtered through a 0.22 μm membrane, and the filters enriched in alkaline peptone water for 6 h and then used directly in the duplex PCR assay. The
PCR procedure coupled with enrichment could detect as few as 1.2 c.f.u./ml in ground water, 1.2 × 102 c.f.u. ml−1 in sewer water and 1.2 × 103c.f.u. ml−1 in tap water. The assay was successfully applied directly for screening of environmental potable water samples collected
from a cholera-affected area. The proposed method is simple and can be used for environmental monitoring of toxigenic as well
as non-toxigenic V. cholerae. 相似文献
997.
Usha Natraj 《Journal of biosciences》1989,14(2):101-109
The role of gonadotropins and estrogen on the regulation of ovarian ornithine decarboxylase was studied during follicular
differentiation/maturation. In intact immature rats follicular differentiation/maturation was initiated with sequential administration
of estrogen and follicle stimulating hormone. Ornithine decarboxylase activity in response to human chorionic gonadotropin
was markedly enhanced (2-fold) in rats with preovulatory antral follicles when compared to rats with non-ovulatory follicles.
This increase could be attributed to the alteration in the turnover of the enzyme. Following follicle maturation the half
life of the human chorionic gonadotropin stimulated ornithine decarboxylase was increased from 18 to 62 min. This increase
in half life was associated with differentition of follicles. In the estrogen treated group (which does not induce follicular
differentiation), the half life of the enzyme remained unaltered. The regulation of ornithine decarboxylase through the formation
of protein inhibitor antizyme induced by diamino hexane, was unaltered during follicular differentiation. 相似文献
998.
A detailed study of the in vitro interaction between Zn2+ and α-amylases from different origins has shown that under physiological conditions 相似文献
999.
A stochastic model for the firing of a neuron with refractory properties is treated analytically. Refractory behavior is modeled by a threshold function θ(t) which is infinite immediately after the neuron fires, as well as during the absolute refractory period, and then decreases monotonically to the quiescent threshold level, θ∞, during the relative refractory period. Using Wald's identity, input-output relations are derived analytically for the exponential threshold which has a time constant equal to the membrane time constant. A method for computing these relations for a general threshold is presented and is explicitly used for the general exponential threshold and the Hagiwara threshold, θ(t) = θ∞eα/t, where a is a constant. 相似文献
1000.
A comparison of the tryptic peptide maps of serine hydroxymethyltransferase from sheep, human, ox livers and Escherichia coli revealed that the mammalian enzymes were similar, while the bacterial enzyme exhibited differences in the primary structure. N-terminus of the reduced carboxymethylated sheep liver enzyme was acetylated. Serine hydroxymethyltransferase was hydrolyzed with trypsin and fragments of peptides were separated by high performance liquid chromatography using a combination of gel permeation, reverse phase and ion-pair chromatography. The peptides were sequenced manually using the 4-N,N'-dimethyl aminoazobenzene-4'-isothiocyanate/phenyl isothiocyanate double coupling method. The tryptic peptides with 80% homology or above were aligned on the rabbit liver enzyme sequence. 相似文献