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921.
A vast repertoire of Dscam binding specificities arises from modular interactions of variable Ig domains 总被引:1,自引:0,他引:1
Dscam encodes a family of cell surface proteins required for establishing neural circuits in Drosophila. Alternative splicing of Drosophila Dscam can generate 19,008 distinct extracellular domains containing different combinations of three variable immunoglobulin domains. To test the binding properties of many Dscam isoforms, we developed a high-throughput ELISA-based binding assay. We provide evidence that 95% (>18,000) of Dscam isoforms exhibit striking isoform-specific homophilic binding. We demonstrate that each of the three variable domains binds to the same variable domain in an opposing isoform and identify the structural elements that mediate this self-binding of each domain. These studies demonstrate that self-binding domains can assemble in different combinations to generate an enormous family of homophilic binding proteins. We propose that this vast repertoire of Dscam recognition molecules is sufficient to provide each neuron with a unique identity and homotypic binding specificity, thereby allowing neuronal processes to distinguish between self and nonself. 相似文献
922.
923.
Sun P Zhang X Zang X Zhou X Chen Y Arunakumara KK Liang B 《Biotechnology letters》2007,29(7):1013-1018
Oral delivery of salmon calcitonin (sCT) to rats via a recombinant Saccharomyces cerevisiae was assessed. A synthetic sCT gene was cloned and expressed in S. cerevisiae yAGA2-sCT. Recombinant salmon calcitonin (rsCT) expression was detected by flow cytometry. The resorption activity of osteoclasts
was inhibited by 3 × 10−6 M rsCT. Oral administration of 5 g lyophilized yAGA2-sCT/kg to hypercalcemic rats decreased serum calcium from 2.8 ± 0.02–2.7 ± 0.02 mM. 相似文献
924.
Two novel cobalt(III) mixed-polypyridyl complexes [Co(phen)(2)(dpta)](3+) and [Co(phen)(2)(amtp)](3+) (phen=1,10-phenanthroline, dpta=dipyrido-[3,2-a;2',3'-c]- thien-[3,4-c]azine, amtp=3-amino-1,2,4-triazino[5,6-f]1,10-phenanthroline) have been synthesized and characterized. The interaction of these complexes with calf thymus DNA was investigated by spectroscopic, cyclic voltammetry, and viscosity measurements. Results suggest that the two complexes bind to DNA via an intercalative mode. Moreover, these Co(III) complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365nm. The mechanism studies reveal that hydroxyl radical (OH()) is likely to be the reactive species responsible for the cleavage of plasmid DNA by [Co(phen)(2)(dpta)](3+) and superoxide anion radical (O(2)(-)) acts as the key role in the cleavage reaction of plasmid DNA by [Co(phen)(2)(amtp)](3+). 相似文献
925.
Cell growth, flavonoids biosynthesis and L-phenylalanine ammonia-lyase (PAL) activity were studied in callus cultures of Saussurea medusa Maxim. under different types of spectral radiance. After 21 days, red light significantly improved the callus growth, but
inhibited the biosynthesis of flavonoids in callus cultures. However, blue light was found to enhance the biosynthesis of
flavonoids, although callus growth under this spectrum was comparable with that under white and other coloured spectra, such
as green and yellow. The accumulation of flavonoids in callus cultures was related to the PAL activity, which was found to
be stimulated by the spectral composition of irradiation. 相似文献
926.
Jinchuan Deng Bin Liao Mai Ye Dongmei Deng Chongyu Lan Wensheng Shu 《Plant and Soil》2007,297(1-2):83-92
The genetic diversity and population structure of seven populations of Sedum alfredii growing in lead/zinc (Pb/Zn) mine spoils or in uncontaminated soils from eastern and southern China were investigated using
random amplified polymorphic DNA (RAPD) technology. Four of the sampled sites were heavily contaminated with heavy metals
(Zn, Cd, Pb), and extremely high concentrations of Zn, Cd, and Pb were found among these corresponding populations. A significant
reduction of genetic diversity was detected in the mining populations. The reduction of genetic diversity could be derived
from a bottleneck effect and might also be attributed to the prevalence of vegetative reproduction of the mining populations.
Analysis of molecular variance (AMOVA) and the unweighted pair group method with arithmetic mean (UPGMA) tree derived from
genetic distances further corroborated that the genetic differentiation between mine populations and uncontaminated populations
was significant. Polymorphism with the heavy metal accumulation capability of S. alfredii probably due to the genetic variation among populations and heavy metal contamination could have more impact on the genetic
diversity and population structure of S. alfredii populations than geographic distance. 相似文献
927.
The SQUA family (AP1/FUL family) of MADS-box genes plays an important role in the transition from the vegetative to the reproductive development of
angiosperms, and its origin might be concurrent with fixation of floral structure in angiosperms. Here, we isolated two Phalaenopsis MADS-box genes designated ORAP11 and ORAP13, both of which belong to the monocot FUL-like clade of the SQUA family. RT-PCR showed that both genes are strongly expressed in the floral bud, and also detected in the vegetative organs.
During later stages, ORAP11 was only detected in the column, but ORAP13 signal was absent from all of the floral organs. In-situ hybridization experiments detected both genes in the tips and margins
of developing petals and lips, the developing column, and ovule. Over-expression of both genes in tobacco induced early flowering
and changed plant architecture. Our results suggest that in Phalaenopsis, both genes might share partly redundant activities and play important roles in the process of floral transition and morphological
architecture.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
928.
929.
Increased sequence diversity coverage improves detection of HIV-specific T cell responses 总被引:2,自引:0,他引:2
Frahm N Kaufmann DE Yusim K Muldoon M Kesmir C Linde CH Fischer W Allen TM Li B McMahon BH Faircloth KL Hewitt HS Mackey EW Miura T Khatri A Wolinsky S McMichael A Funkhouser RK Walker BD Brander C Korber BT 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(10):6638-6650
The accurate identification of HIV-specific T cell responses is important for determining the relationship between immune response, viral control, and disease progression. HIV-specific immune responses are usually measured using peptide sets based on consensus sequences, which frequently miss responses to regions where test set and infecting virus differ. In this study, we report the design of a peptide test set with significantly increased coverage of HIV sequence diversity by including alternative amino acids at variable positions during the peptide synthesis step. In an IFN-gamma ELISpot assay, these "toggled" peptides detected HIV-specific CD4(+) and CD8(+) T cell responses of significantly higher breadth and magnitude than matched consensus peptides. The observed increases were explained by a closer match of the toggled peptides to the autologous viral sequence. Toggled peptides therefore afford a cost-effective and significantly more complete view of the host immune response to HIV and are directly applicable to other variable pathogens. 相似文献
930.