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991.
Pseudomonas sp. strain TXG6-1, a chitinolytic gram-negative bacterium, was isolated from a vegetable field in Taixing city, Jiangsu Province, China. In this study, a Pseudomonas chitinase C gene (PsChiC) was isolated from the chromosomal DNA of this bacterium using a pair of specific primers. The PsChiC gene consisted of an open reading frame of 1443 nucleotides and encoded 480 amino acid residues with a calculated molecular mass of 51.66 kDa. The deduced PsChiC amino acid sequence lacked a signal sequence and consisted of a glycoside hydrolase family 18 catalytic domain responsible for chitinase activity, a fibronectin type III-like domain (FLD) and a C-terminal chitin-binding domain (ChBD). The amino acid sequence of PsChiCshowed high sequence homology (> 95%) with chitinase C from Serratia marcescens. SDS-PAGE showed that the molecular mass of chitinase PsChiC was 52 kDa. Chitinase assays revealed that the chitobiosidase and endochitinase activities of PsChiCwere 51.6- and 84.1-fold higher than those of pET30a, respectively. Although PsChiC showed little insecticidal activity towards Spodoptera litura larvae, an insecticidal assay indicated that PsChiC increased the insecticidal toxicity of SpltNPV by 1.78-fold at 192 h and hastened death. These results suggest that PsChiC from Pseudomonas sp. could be useful in improving the pathogenicity of baculoviruses. 相似文献
992.
Canying Liu Huajun Zheng Minjun Yang Zhuofei Xu Xiangru Wang Liuya Wei Biao Tang Feng Liu Yanyan Zhang Yi Ding Xibiao Tang Bin Wu Timothy J. Johnson Huanchun Chen Chen Tan 《BMC genomics》2015,16(1)
Background
Strains of extraintestinal pathogenic Escherichia coli (ExPEC) can invade and colonize extraintestinal sites and cause a wide range of infections. Genomic analysis of ExPEC has mainly focused on isolates of human and avian origins, with porcine ExPEC isolates yet to be sequenced. To better understand the genomic attributes underlying the pathogenicity of porcine ExPEC, we isolated two E. coli strains PCN033 and PCN061 from pigs, assessed their in vivo virulence, and completed and compared their genomes.Results
Animal experiments demonstrated that strain PCN033, but not PCN061, was pathogenic in a pig model. The chromosome of PCN033 was 384 kb larger than that of PCN061. Among the PCN033-specific sequences, genes encoding adhesins, unique lipopolysaccharide, unique capsular polysaccharide, iron acquisition and transport systems, and metabolism were identified. Additionally, a large plasmid PCN033p3 harboring many typical ExPEC virulence factors was identified in PCN033. Based on the genetic variation between PCN033 and PCN061, corresponding phenotypic differences in flagellum-dependent swarming motility and metabolism were verified. Furthermore, the comparative genomic analyses showed that the PCN033 genome shared many similarities with genomic sequences of human ExPEC strains. Additionally, comparison of PCN033 genome with other nine characteristic E. coli genomes revealed 425 PCN033-special coding sequences. Genes of this subset included those encoding type I restriction-modification (R-M) system, type VI secretion system (T6SS) and membrane-associated proteins.Conclusions
The genetic and phenotypic differences between PCN033 and PCN061 could partially explain their differences in virulence, and also provide insight towards the molecular mechanisms of porcine ExPEC infections. Additionally, the similarities between the genomes of PCN033 and human ExPEC strains suggest that some connections between porcine and human ExPEC strains exist. The first completed genomic sequence for porcine ExPEC and the genomic differences identified by comparative analyses provide a baseline understanding of porcine ExPEC genetics and lay the foundation for their further study.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1890-9) contains supplementary material, which is available to authorized users. 相似文献993.
994.
Yan-Fang Liu Rong-Zhen Liao Wan-Jian Ding Jian-Guo Yu Ruo-Zhuang Liu 《Journal of biological inorganic chemistry》2011,16(5):745-752
The reaction mechanism of the hydration of acetylene to acetaldehyde catalyzed by [WIVO(mnt)2]2− (where mnt2− is 1,2-dicyanoethylenedithiolate) is studied using density functional theory. Both the uncatalyzed and the catalyzed reaction
are considered to find out the origin of the catalysis. Three different models are investigated, in which an aquo, a hydroxo,
or an oxo coordinates to the tungsten center. A first-shell mechanism is suggested, similarly to recent calculations on tungsten-dependent
acetylene hydratase. The acetylene substrate first coordinates to the tungsten center in an η2 fashion. Then, the tungsten-bound hydroxide activates a water molecule to perform a nucleophilic attack on the acetylene,
resulting in the formation of a vinyl anion and a tungsten-bound water molecule. This is followed by proton transfer from
the tungsten-bound water molecule to the newly formed vinyl anion intermediate. Tungsten is directly involved in the reaction
by binding and activating acetylene and providing electrostatic stabilization to the transition states and intermediates.
Three other mechanisms are also considered, but the associated energetic barriers were found to be very high, ruling out those
possibilities. 相似文献
995.
Ding Ding Huang Peng Pan Ying-Qiu Chen Shu-Qing 《World journal of microbiology & biotechnology》2011,27(12):2957-2967
In China, staphylococcin injection has been commonly used in the combined treatment of cancer to enhance the systemic immune
response and reduce the toxicities associated with chemotherapy and radiation therapy. It is claimed that the main active
component in the injection is staphylococcal enterotoxin C2 (SEC2). To determine whether other serological types of staphylococcal
enterotoxins (SEs) could also be present in the injection products, in this study, the distribution of se genes (from sea to see, from seg to seu) in the one and only production strain of Staphylococcus aureus from one manufacturing company was analyzed by PCR method. In addition, sek and seq genes were cloned from the strain and the corresponding recombinant proteins, rSEK and rSEQ, were expressed in Escherichia coli and purified by affinity chromatography and anion-exchange chromatography. The superantigenic properties of the two recombinant
proteins were then measured by MTT method. The PCR results showed that seven se genes are harbored by the production strain. However, sec2 gene was not detected. The results of MTT assay showed that rSEK and rSEQ could elicit strong stimulatory effects on proliferation
and cytotoxicity of murine splenocytes in vitro. Overall, the results in this study indicated that one or a plurality of the
seven SEs may be present in the related products, and that the two recombinant SEs are promising candidates as immunomodulatory
agents for cancer therapy. 相似文献
996.
Most of the DNA logic gates employ fluorescent or colorometric signals as their outputs, which were limited by the cumbersome handling procedures, lack of portability and lower sensitivity. To the best of our knowledge, the logic gates with electrochemiluminescent (ECL) signal as their outputs have not been reported. In response, we report here the construction of DNA molecular logic gates that produce ECL signals as their outputs, having the advantages of versatility, low background and simplified optical setup. The logic gates are based on the T-rich or C-rich oligonucleotides for the selective analysis of Hg(2+) and Ag(+) ions using energy or electron transfer-quenching path. Efficient and stable quenching of ECL of Ru bis(2,2'-bipyridine) (2,2'-bipyridine-4,4'-dicarboxylic acid) N-hydroxysuccinimide ester by oxidizing ferrocene at the Au electrode enabled us to use Hg(2+) and Ag(+) ions as inputs that activate logic gates, and to execute ECL of Ru(II) as readout signals for logic gate operations. 相似文献
997.
Ding L Zhu J Zheng C Sheng C Qi J Liu X Han G Zhao J Lv J Zhou Y 《Bioorganic & medicinal chemistry letters》2011,21(22):6674-6677
A series of new substituted 4-amino-N-(diaminomethylene) benzenesulfonamides were synthesized and their in vitro acrosin inhibitory activities were evaluated. Most of the compounds showed potent acrosin inhibitory activities with compounds 4o and 4p being significantly more potent than the control compound N-alpha-tosyl-l-lysyl-chloromethyl-ketone (TLCK). The compounds provide a new scaffold for the development of acrosin inhibitory agents. 相似文献
998.
三种接种物启动Anammox-EGSB反应器的性能 总被引:2,自引:0,他引:2
为了优选接种物和加速Anammox反应器启动,分别以厌氧产甲烷污泥 (Anaerobic methanogenic sludge,AMS)、新鲜厌氧氨氧化污泥 (Fresh Anammox sludge,FAS) 和储藏厌氧氨氧化污泥 (Stored Anammox sludge,SAS) 作为接种物,研究了厌氧氨氧化膨胀颗粒污泥床 (Anammox-EGSB) 反应器 (R1、R2和R3) 的启动性能。结果表明:3种接种物均能成功启动Anammox-EGSB反应器,启动性能的优劣次序为:R2 (接种物为 相似文献
999.
1000.
Wang X Zhang S Sun C Yuan ZG Wu X Wang D Ding Z Hu R 《Journal of microbiology and biotechnology》2011,21(4):366-373
We characterized the proteomes of murine N2a cells following infection with three rabies virus (RV) strains, characterized by distinct virulence phenotypes (i.e., virulent BD06, fixed CVS-11, and attenuated SRV9 strains), and identified 35 changes to protein expression using two-dimensional gel electrophoresis in whole-cell lysates. The annotated functions of these proteins are involved in various cytoskeletal, signal transduction, stress response, and metabolic processes. Specifically, a-enolase, prx-4, vimentin, cytokine-induced apoptosis inhibitor 1 (CIAPIN1) and prx-6 were significantly up-regulated, whereas Trx like-1 and galectin-1 were down-regulated following infection of N2a cells with all three rabies virus strains. However, comparing expressions of all 35 proteins affected between BD06-, CVS-11-, and SRV9-infected cells, specific changes in expression were also observed. The up-regulation of vimentin, CIAPIN1, prx-4, and 14-3-3 theta/delta, and downregulation of NDPK-B and HSP-1 with CVS and SRV9 infection were ≥ 2 times greater than with BD06. Meanwhile, Zfp12 protein, splicing factor, and arginine/serine-rich 1 were unaltered in the cells infected with BD06 and CVS- 11, but were up-regulated in the group infected with SRV9. The proteomic alterations described here may suggest that these changes to protein expression correlate with the rabies virus' adaptability and virulence in N2a cells, and hence provides new clues as to the response of N2a host cells to rabies virus infections, and may also aid in uncovering new pathways in these cells that are involved in rabies infections. Further characterization of the functions of the affected proteins may contribute to our understanding of the mechanisms of RV infection and pathogenesis. 相似文献