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991.
microRNAs(又称miRNAs或miRs)是一类长度为19-24个核苷酸的单链非编码RNA分子。miRNA通过与其靶向的mRNA分子序列特异性互补配对,调节mRNA表达水平,抑制转录后的蛋白翻译。miRNA在肿瘤中既可作为致癌因子也可作为抑癌因。本研究前期已报道miR-26b在前列腺癌细胞系中低表达,并且抑制细胞自噬。本研究进一步全面揭示miR-26b对前列腺肿瘤细胞的作用。我们发现过表达miR-26b能够在体外抑制前列腺癌细胞的增殖和侵袭,并抑制裸鼠体内原位异种前列腺肿瘤的生长。为了探究miR-26b对前列腺癌细胞增殖和侵袭的潜在调控机制,我们进行了表达谱芯片鉴定miR-26b调控基因。表达谱芯片分析表明,在前列腺癌细胞系PC-3中过表达miR-26b后,显著上调的基因57个,显著下调的基因55个(变化倍数均大于2,且P值小于0.05)。差异基因的功能多与细胞增殖、凋亡调控、蛋白磷酸化和泛素化修饰调控过程相关,并且富集在多种信号通路中,例如TNF和TGF-β信号通路。在这些筛选出的基因中,CEACAM6表达水平下调2.17倍;序列分析及实验验证表明,CEACAM6的3’UTR区存在miR-26b的互补序列,是miR-26b的直接靶标。本研究证明了miR-26b能够靶向结合抑制CEACAM6的表达,从而抑制前列腺癌细胞在体外和体内的细胞增殖和侵袭活性,miR-26b是前列腺癌中的抑癌microRNA。 相似文献
992.
Binding of fluphenazine with human serum albumin in the presence of rutin and quercetin: An evaluation of food‐drug interaction by spectroscopic techniques 下载免费PDF全文
Jiao‐Jiao Jing Bin Liu Xin Wang Xin Wang Ling‐Ling He Xue‐Yuan Guo Ming‐Ling Xu Qian‐Yu Li Bo Gao Bo‐Yang Dong 《Luminescence》2017,32(6):1056-1065
The interactions between human serum albumin (HSA) and fluphenazine (FPZ) in the presence or absence of rutin or quercetin were studied by fluorescence, absorption and circular dichroism (CD) spectroscopy and molecular modeling. The results showed that the fluorescence quenching mechanism was static quenching by the formation of an HSA–FPZ complex. Entropy change (ΔS 0) and enthalpy change (ΔH 0) values were 68.42 J/(mol? K) and ?4.637 kJ/mol, respectively, which indicated that hydrophobic interactions and hydrogen bonds played major roles in the acting forces. The interaction process was spontaneous because the Gibbs free energy change (ΔG 0) values were negative. The results of competitive experiments demonstrated that FPZ was mainly located within HSA site I (sub‐domain IIA). Molecular docking results were in agreement with the experimental conclusions of the thermodynamic parameters and competition experiments. Competitive binding to HSA between flavonoids and FPZ decreased the association constants and increased the binding distances of FPZ binding to HSA. The results of absorption, synchronous fluorescence, three‐dimensional fluorescence, and CD spectra showed that the binding of FPZ to HSA caused conformational changes in HSA and simultaneous effects of FPZ and flavonoids induced further HSA conformational changes. 相似文献
993.
994.
Ri Wei Xia Xue Mei Yin Wei Yun Qin Guo Qiang Zhu Sheng Long Wu Wen Bin Bao 《Genes & genomics.》2017,39(11):1285-1295
Enterogenic Escherichia coli (ETEC) F18 strains are the main pathogenic bacteria causing severe diarrhea in humans and domestic animals. However, the information about synonymous codon usage pattern of ETEC F18 genome remains unclear. We conducted a genome-wide analysis of synonymous codon usage patterns in the ETEC F18 strain SRA: SAMN02471895. After filtering of the complete genome sequence, 4327 coding sequences were analyzed using multivariate statistical methods to calculate synonymous codon usage patterns and to evaluate the influence of various factors in shaping the codon usage. The mean GC content was 51.38%, with a slight preference for G/C-ending codons. Twenty-two codons were determined as ‘‘optimal codons”. ENC plots showed some of the genes were on or close to the expected curve, while only points with low-ENC values were below the curve. PR2 analysis showed that GC and AT were not used proportionally, suggesting major roles for mutational pressure and natural selection in shaping usage. Neutrality plots showed a significant correlation between GC12 and GC3, suggesting that mutational pressure is responsible for nucleotide composition in shaping the strength of codon usage. Translational selection was the main factor shaping the codon usage pattern of ETEC F18 genome, while other factors such as protein length, GRAVY and ARO values also influenced codon usage to some extent. We analyzed the codon usage pattern systematically and identified the factors shaping codon usage bias in the ETEC F18 genome. Such information further elucidates the mechanisms of synonymous codon usage bias and provides the basis of molecular genetic engineering and evolutionary studies. 相似文献
995.
996.
Apoptosis Induced by Infection of Primary Brain Cultures with Diverse Human Immunodeficiency Virus Type 1 Isolates: Evidence for a Role of the Envelope 总被引:5,自引:3,他引:5 下载免费PDF全文
Asa Ohagen Sajal Ghosh Jianglin He Karen Huang Youzhi Chen Menglan Yuan Rapin Osathanondh Suzanne Gartner Bin Shi George Shaw Dana Gabuzda 《Journal of virology》1999,73(2):897-906
Apoptosis of neurons and astrocytes is induced by human immunodeficiency type 1 (HIV-1) infection in vitro and has been demonstrated in brain tissue from patients with AIDS. We analyzed a panel of diverse HIV-1 primary isolates for the ability to replicate and induce neuronal and astrocyte apoptosis in primary human brain cultures. Apoptosis was induced three- to eightfold by infection with the blood-derived HIV-1 isolates 89.6, SG3, and ADA. In contrast, the brain-derived HIV-1 isolates YU2, JRFL, DS-br, RC-br, and KJ-br did not induce significant levels of apoptosis. The ability of HIV-1 isolates to induce apoptosis was independent of their replication capacity. Studies of recombinant chimeras between the SG3 and YU2 viruses showed that replacement of the YU2 Env with the SG3 Env was sufficient to confer the ability to induce apoptosis to the YU2 virus. Replacement of the Env V3 regions alone largely conferred the phenotypes of the parental clones. The SG3 Env used CXCR4 and CCR3 as coreceptors for virus entry, whereas YU2 used CCR5 and CCR3. The V3 regions of SG3 and YU2 conferred the ability to use CXCR4 and CCR5, respectively. In contrast, the 3′ region of Env, particularly the C3V4 region, was required in conjunction with the V3 region for efficient use of CCR3. These results provide evidence that Env is a major determinant of neurodegenerative mechanisms associated with HIV-1 infection in vitro and raise the possibility that blood-derived viruses which emerge during the late stages of disease may affect disease progression in the central nervous system. 相似文献
997.
普通小麦-中间偃麦草TAI-27中附加染色体的显微切割及特异性探针的筛选 总被引:1,自引:0,他引:1
试验以长穗偃麦草基因组DNA为探针 ,与普通小麦 中间偃麦草TAI 2 7进行染色体原位杂交 ,表明有 4条与长穗偃麦草同源的染色体 ;以P .stipifolia (St)基因组DNA为探针 ,有 4条与St同源的染色体 .这说明TAI 2 7中有 4条St染色体 .TAI 2 7是异代换 附加系 .对TAI 2 7中附加的中间偃麦草染色体进行显微切割 ,并建立其微克隆库 ,从中筛选获得了中间偃麦草的特异性探针 ,同源性分析表明该序列为一新序列 .这为进一步筛选抗病、抗逆和优质基因打下基础 . 相似文献
998.
999.
土壤氮库对生态系统的养分循环至关重要。目前多数研究主要关注氮沉降对土壤总氮的影响, 而对土壤不同有机质组分的氮库对氮沉降响应的研究较为缺乏。该研究基于内蒙古典型草地的长期多水平施氮(0、8、32、64 g·m-2·a-1)实验平台, 利用土壤密度分级方法, 探究氮添加处理13年后典型草地中两种土壤有机质组分(颗粒态有机质(POM), 矿质结合态有机质(MAOM))氮含量的变化及调控机制。结果显示: 土壤总碳含量、POM和MAOM的碳含量在施氮处理间均没有显著差异。土壤总氮含量则随着施氮水平增加呈显著增加的趋势, 同时施氮处理下POM的氮含量显著上升, 而MAOM的氮含量没有变化。进一步分析发现, 施氮促进植物地上生物量积累, 增加了凋落物量及其氮含量, 从而导致POM的氮含量增加。由于MAOM主要通过黏土矿物等吸附土壤中小分子有机质形成, 其氮含量受土壤中黏粒与粉粒含量影响, 而与氮添加水平无显著相关关系。该研究结果表明长期氮添加促进土壤氮库积累, 但增加的氮主要分布在稳定性较低的POM中, 受干扰后容易从生态系统中流失。为了更准确地评估和预测氮沉降对陆地生态系统的氮循环过程的影响, 应考虑土壤中不同有机质组分的差异响应。 相似文献
1000.