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141.
左旋千金藤啶碱D1激动—D2阻滞作用引起伏核双相放电活动的电生理研究 总被引:3,自引:0,他引:3
为确定左旋千金藤啶碱(SPD)对中脑边缘DA神经系统的作用特性,本研究采用细胞外记录的电生理学方法,观察微电泳和尾静脉给药对6-OHDA损毁及未损毁大鼠的伏核(NAc)单位放电的影响。结果显示:SPD累积给药(0.02-2mg/kg,iv)可诱发NAc神经元双相放电特征,即小剂量抑制、大剂量兴奋。预先给予D2受体拮抗剂speperone,SPD则仅产生兴奋效应,并被D1拮抗剂SCH-23390所翻 相似文献
142.
Development of a chromosome-plasmid balanced lethal system for Lactobacillus acidophilus with thyA gene as selective marker 总被引:6,自引:0,他引:6
A chromosome-plasmid balanced lethal gene delivery system for Lactobacillus acidophilus based on the thyA gene was developed. The selected L. acidophilus DOM La strain carries a mutated thyA gene and has an obligate requirement for thymidine. This strain can be used as a host for the constructed shuttle vector pFXL03, lacking antibiotic-resistant markers but having the wild-type thyA gene from L. casei which complements the thyA chromosomal mutation. The vector also contains the replicon region from plasmid pUC19 and that of the Lactococcus plasmid pWV01, which allows the transfer between Escherichia coli, L. casei and L. acidophilus. Eight unique restriction sites (i.e., PstI, HindIII, SphI, SalI, AccI, XbaI, KpnI and SacI) are available for cloning. After 40-time transfers in modified MRS medium, no plasmid loss was observed. The vector pFXL03 is potentially useful as a food-grade vaccine delivery system for L. acidophilus. 相似文献
143.
Fu M Rao M Bouras T Wang C Wu K Zhang X Li Z Yao TP Pestell RG 《The Journal of biological chemistry》2005,280(17):16934-16941
The cyclin D1 gene encodes the labile serum-inducible regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma protein. Overexpression of cyclin D1 promotes cellular proliferation and normal physiological levels of cyclin D1 function to inhibit adipocyte differentiation in vivo. We have previously shown that cyclin D1 inhibits peroxisome proliferator-activated receptor (PPAR)gamma-dependent activity through a cyclin-dependent kinase- and retinoblastoma protein-binding-independent mechanism. In this study, we determined the molecular mechanism by which cyclin D1 regulated PPARgamma function. Herein, murine embryonic fibroblast (MEF) differentiation by PPARgamma ligand was associated with a reduction in histone deacetylase (HDAC1) activity. Cyclin D1-/- MEFs showed an increased propensity to undergo differentiation into adipocytes. Genetic deletion of cyclin D1 reduced HDAC1 activity. Reconstitution of cyclin D1 into the cyclin D1-/- MEFs increased HDAC1 activity and blocked PPARgamma-mediated adipogenesis. PPARgamma activity was enhanced in cyclin D1-/- cells. Reintroduction of cyclin D1 inhibited basal and ligand-induced PPARgamma activity and enhanced HDAC repression of PPARgamma activity. Cyclin D1 bound HDAC in vivo and preferentially physically associated with HDAC1, HDAC2, HDAC3, and HDAC5. Chromatin immunoprecipitation assay demonstrated that cyclin D1 enhanced recruitment of HDAC1 and HDAC3 and histone methyltransferase SUV39H1 to the PPAR response element of the lipoprotein lipase promoter and decreased acetylation of total histone H3 and histone H3 lysine 9. Collectively, these studies suggest an important role of cyclin D1 in regulation of PPARgamma-mediated adipocyte differentiation through recruitment of HDACs to regulate PPAR response element local chromatin structure and PPARgamma function. 相似文献
144.
Wang Shujing Liu Yan Lin Xuesong Fu Xue Xu Jianyong Liu Xinghan 《Frontiers of Biology in China》2007,2(3):276-283
To obtain an anti-tumor peptide of Tumstatin and detect its biological activity, the nucleotide sequence encoding 185–203
amino acids (19peptide) of Tumstatin was synthesized and inserted into the fusion protein vector pTYB2. After identification
by sequencing and restriction endonucleases, the recombined vector was transformed into BL-21 (DE3) E. coli competent cells. Transformed E. coli BL-21 (DE3) were induced by isopropyl-β-thiogalactopyranoside (IPTG), and then expressed. By 1,4-dithiothreitol (DTT) reduction,
the soluble 19peptide was obtained from a chitin affinity chromatograph. The biological activity of 19peptide was determined
by 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenytetrazolium bromide (MTT) assay, cell growth curve, the effect of the ascitic fluid
transfevent H22 hepatoma on mice and via histopathological slices. The purified 19peptide directly inhibited proliferation
and migration of murine B16 melanoma cells, SMMC-7721hepatoma carcinoma cells and human umbilical vein endothelial cells (HUVEC).
The tumor inhibition rate of mice ascitic fluid transfevent H22 hepatoma was 48.46%. Histopathological slices showed that
it could promote tumor tissue necrosis and decrease the density of blood vessels. With higher anti-tumor activity, 19peptide
has the potential to become a novel, potent anti-tumor agent.
Translated from Chinese Journal of Biochemistry and Molecular Biology, 2005, 21(3): 322–328 [译自: 中国生物化学与分子生物学学报] 相似文献
145.
Wenzheng Zhang Sheng Fu Xuefeng Liu Xuelian Zhao Wenchi Zhang Wei Peng Congying Wu Yuanyuan Li Xuemei Li Mark Bartlam Zong-Hao Zeng Qimin Zhan Zihe Rao 《蛋白质与细胞》2011,2(10):814
The human Gadd45 protein family plays critical roles in DNA repair, negative growth control, genomic stability, cell cycle checkpoints and apoptosis. Here we report the crystal structure of human Gadd45, revealing a unique dimer formed via a bundle of four parallel helices, involving the most conserved residues among the Gadd45 isoforms. Mutational analysis of human Gadd45 identified a conserved, highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen (PCNA), p21 and cdc2, suggesting that the parallel dimer is the active form for the interaction. Cellular assays indicate that: (1) dimerization of Gadd45 is necessary for apoptosis as well as growth inhibition, and that cell growth inhibition is caused by both cell cycle arrest and apoptosis; (2) a conserved and highly acidic patch on the dimer surface, including the important residues Glu87 and Asp89, is a putative interface for binding proteins related to the cell cycle, DNA repair and apoptosis. These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function. 相似文献
146.
A male sterility-associated cytotoxic protein ORF288 in Brassica juncea causes aborted pollen development 总被引:1,自引:0,他引:1
Jing B Heng S Tong D Wan Z Fu T Tu J Ma C Yi B Wen J Shen J 《Journal of experimental botany》2012,63(3):1285-1295
Cytoplasmic male sterility (CMS) is a widespread phenomenon in higher plants, and several studies have established that this maternally inherited defect is often associated with a mitochondrial mutant. Approximately 10 chimeric genes have been identified as being associated with corresponding CMS systems in the family Brassicaceae, but there is little direct evidence that these genes cause male sterility. In this study, a novel chimeric gene (named orf288) was found to be located downstream of the atp6 gene and co-transcribed with this gene in the hau CMS sterile line. Western blotting analysis showed that this predicted open reading frame (ORF) was translated in the mitochondria of male-sterile plants. Furthermore, the growth of Escherichia coli was significantly repressed in the presence of ORF288, which indicated that this protein is toxic to the E. coli host cells. To confirm further the function of orf288 in male sterility, the gene was fused to a mitochondrial-targeting pre-sequence under the control of the Arabidopsis APETALA3 promoter and introduced into Arabidopsis thaliana. Almost 80% of transgenic plants with orf288 failed to develop anthers. It was also found that the independent expression of orf288 caused male sterility in transgenic plants, even without the transit pre-sequence. Furthermore, transient expression of orf288 and green fluorescent protein (GFP) as a fused protein in A. thaliana protoplasts showed that ORF288 was able to anchor to mitochondria even without the external mitochondrial-targeting peptide. These observations provide important evidence that orf288 is responsible for the male sterility of hau CMS in Brassica juncea. 相似文献
147.
Lung cancer is among the most lethal malignancies with a high metastasis and recurrence rate. Recent studies indicate that tumors contain a subset of stem-like cancer cells that possess certain stem cell properties. Herein, we used Hoechst 33342 dye efflux assay and flow cytometry to isolate and characterize the side population (SP) cells from human lung cancer cell line NCI-H460 (H460). We show that the H460 SP cells harbor stem-like cells as they can readily form anchorage-independent floating spheres, possess great proliferative potential, and exhibit enhanced tumorigenicity. Importantly, the H460 SP cells were able to self-renew both in vitro and in vivo. Finally, we show that the H460 SP cells preferentially express ABCG2 as well as SMO, a critical mediator of the Hedgehog (HH) signaling, which seems to play an important role in H460 lung cancer cells as its blockage using Cyclopamine greatly inhibits cell-cycle progression. Collectively, our results lend further support to the existence of lung cancer stem cells and also implicate HH signaling in regulating large-cell lung cancer (stem) cells. 相似文献
148.
149.
150.
Cheng Du Baosheng Ge Zhongfeng Liu Kai Fu Wing C Chan Timothy W McKeithan 《BMC biotechnology》2006,6(1):28-11