全文获取类型
收费全文 | 1300篇 |
免费 | 97篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 50篇 |
2020年 | 24篇 |
2019年 | 31篇 |
2018年 | 29篇 |
2017年 | 15篇 |
2016年 | 37篇 |
2015年 | 60篇 |
2014年 | 59篇 |
2013年 | 79篇 |
2012年 | 102篇 |
2011年 | 92篇 |
2010年 | 53篇 |
2009年 | 57篇 |
2008年 | 69篇 |
2007年 | 56篇 |
2006年 | 64篇 |
2005年 | 47篇 |
2004年 | 51篇 |
2003年 | 46篇 |
2002年 | 38篇 |
2001年 | 34篇 |
2000年 | 32篇 |
1999年 | 30篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 23篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1970年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有1397条查询结果,搜索用时 62 毫秒
71.
The influence of surface wettability on the adhesion strength of settled spores of the green alga enteromorpha and the diatom amphora 总被引:1,自引:0,他引:1
Finlay JA Callow ME Ista LK Lopez GP Callow JA 《Integrative and comparative biology》2002,42(6):1116-1122
In this paper we report on the effect of surface wettabilityon surface selection and adhesion properties of settled (adhered)spores of the biofouling marine alga Enteromorpha and cellsof the diatom Amphora, through the use of patterned self-assembledmonolayers (SAMs). The SAMs were formed from alkanethiols terminatedwith methyl (CH3) or hydroxyl (OH) groups, or mixtures of thetwo, creating a discontinuous gradient of wettability as measuredby advancing water contact angle. In the case of Enteromorpha,primary adhesion, as measured by the transition from a motilespore to a settled, sessile organism, is strongly promoted bythe hydrophobic surfaces. On the other hand, adhesion strengthof the settled spores, as measured by resistance to detachmentin a turbulent flow cell, is greatest on a hydrophilic surface.In the case of Amphora, there is little influence of surfacewettability on the primary adhesion of this organism, but motilityis inhibited at contact angles 相似文献
72.
Steele-Mortimer O Brumell JH Knodler LA Méresse S Lopez A Finlay BB 《Cellular microbiology》2002,4(1):43-54
Type III secretion systems (TTSS) are used by Gram-negative pathogens to translocate proteins into eukaryotic host cells. Salmonella enterica serovar Typhimurium (S. Typhimurium) has two of these specialized systems, which are encoded on separate Salmonella pathogenicity islands (SPI-1 and SPI-2) and translocate unique sets of effectors. The specific roles of these systems in Salmonella pathogenesis remain undefined, although SPI-1 is required for bacterial invasion of epithelial cells and SPI-2 for survival/replication in phagocytic cells. However, because SPI-1 TTSS mutants are invasion-incompetent, the role of this TTSS in post-invasion processes has not been investigated. In this study, we have used two distinct methods to internalize a non-invasive SPI-1 TTSS mutant (invA) into cultured epithelial cells: (i) co-internalization with wild-type S. Typhimurium (SPI-1-dependent) and (ii) complementation with the Yersinia pseudotuberculosis invasin (inv) gene (SPI-1-independent). In both cases, internalized invA mutants were unable to replicate intracellularly, indicating that SPI-1 effectors are essential for this process and cannot be complemented by wild-type bacteria in the same cell. Analysis of the biogenesis of SCVs showed that vacuoles containing mutant bacteria displayed abnormal maturation that was dependent on the mechanism of entry. Manipulation of Salmonella-containing vacuole (SCV) biogenesis by pharmacologically perturbing membrane trafficking in the host cell increased intracellular replication of wild-type but not mutant S. Typhimurium This demonstrates a previously unknown role for SPI-1 in vacuole biogenesis and intracellular survival in non-phagocytic cells. 相似文献
73.
Antibiotics are widely useful in medicine, agriculture, and industrial fermentations. However, increasing problems with resistant strains call for restrained use and alternative strategies. Antisense peptide nucleic acids (PNAs) show potent bactericidal effects when targeted against the essential Escherichia coli acpP gene. Aside from attractive antimicrobial therapeutic possibilities for such antisense PNAs, we considered that they could be used as a substitute for antibiotics in bacterial strain selection. Here, treatment of a mixture of E. coli wild-type cells and cells carrying a binding-site altered copy of acpP (acpP-1) with anti-acpP PNA completely killed wild-type cells within 2 h, whereas cells carrying acpP-1 proliferated. Furthermore, electrotransformation of E. coli cells with the plasmid carrying acpP-1 followed by PNA selection gave rise to only true transformants. Unlike previous antibiotic-free selection strategies, this procedure does not require special growth environments or special host strains. Also, the PNA-selected cells grow at a near normal rate. The results open possibilities to use antisense PNAs for strain selection and construction in research and industrial application. 相似文献
74.
Antisense peptide nucleic acids (PNA) can inhibit bacterial gene expression with gene and sequence specificity. Using attached carrier peptides that aid cell permeation, the antisense effects when targeting essential genes are sufficient to prevent growth and even kill bacteria. However, many design uncertainties remain, including the difficult question of target sequence selection. In this study, we synthesized 90 antisense peptide-PNAs to target sequences in a head to tail manner across the entire length of the mRNA encoding beta-lactamase. The results from this scan pointed to the start codon region as most sensitive to inhibition. To confirm and refine the result, a higher-resolution scan was conducted over the start codon region of the beta-lactamase gene and the essential Escherichia coli acpP gene. For both genes, the start codon region, including the Shine-Dalgarno motif, was sensitive, whereas antisense agents targeted outside of this region were largely ineffective. These results are in accord with natural antisense mechanisms, which typically hinder the start codon region, and the sensitivity of this region should hold true for most bacterial genes as well as for other RNase H-independent antisense agents that rely on a steric blocking mechanism. Therefore, although other design parameters are also important, the start codon region in E. coli mRNA is the most reliable target site for antisense PNAs. 相似文献
75.
Virulence factors of the human opportunistic pathogen Serratia marcescens identified by in vivo screening 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kurz CL Chauvet S Andrès E Aurouze M Vallet I Michel GP Uh M Celli J Filloux A De Bentzmann S Steinmetz I Hoffmann JA Finlay BB Gorvel JP Ferrandon D Ewbank JJ 《The EMBO journal》2003,22(7):1451-1460
The human opportunistic pathogen Serratia marcescens is a bacterium with a broad host range, and represents a growing problem for public health. Serratia marcescens kills Caenorhabditis elegans after colonizing the nematode's intestine. We used C.elegans to screen a bank of transposon-induced S.marcescens mutants and isolated 23 clones with an attenuated virulence. Nine of the selected bacterial clones also showed a reduced virulence in an insect model of infection. Of these, three exhibited a reduced cytotoxicity in vitro, and among them one was also markedly attenuated in its virulence in a murine lung infection model. For 21 of the 23 mutants, the transposon insertion site was identified. This revealed that among the genes necessary for full in vivo virulence are those that function in lipopolysaccharide (LPS) biosynthesis, iron uptake and hemolysin production. Using this system we also identified novel conserved virulence factors required for Pseudomonas aeruginosa pathogenicity. This study extends the utility of C.elegans as an in vivo model for the study of bacterial virulence and advances the molecular understanding of S.marcescens pathogenicity. 相似文献
76.
Knodler LA Vallance BA Hensel M Jäckel D Finlay BB Steele-Mortimer O 《Molecular microbiology》2003,49(3):685-704
The intracellular pathogen, Salmonella enterica, translocates type III effectors across its vacuolar membrane into host cells. Herein we describe a new Salmonella effector, PipB2, which has sequence similarity to another type III effector, PipB. In phagocytic cells, PipB2 localizes to the Salmonella-containing vacuole (SCV) and tubular extensions from the SCV, Salmonella-induced filaments (Sifs). We used the specific targeting of PipB2 in macrophages to characterize Sifs in phagocytic cells for the first time. In epithelial cells, PipB2 has a unique localization pattern, localizing to SCVs and Sifs and additionally to vesicles at the periphery of infected cells. We further show that the N-terminal 225-amino-acid residues of PipB2 are sufficient for type III translocation and association with SCVs and Sifs, but not peripheral vesicles. Subcellular fractionation demonstrated that both PipB and PipB2 associate with host cell membranes and resist extraction by high salt, high pH and to a significant extent, non-ionic detergent. Furthermore, PipB and PipB2 are enriched in detergent-resistant microdomains (DRMs), also known as lipid rafts, present on membranes of SCVs and Sifs. The enrichment of Salmonella effectors in DRMs on these intracellular membranes probably permits specific interactions with host cell molecules that are concentrated in these signalling platforms. 相似文献
77.
Scott MG Rosenberger CM Gold MR Finlay BB Hancock RE 《Journal of immunology (Baltimore, Md. : 1950)》2000,165(6):3358-3365
78.
Finlay BB Brumell JH 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2000,355(1397):623-631
Salmonellosis (diseases caused by Salmonella species) have several clinical manifestations, ranging from gastroenteritis (food poisoning) to typhoid (enteric) fever and bacteraemia. Salmonella species (especially Salmonella typhimurium) also represent organisms that can be readily used to investigate the complex interplay that occurs between a pathogen and its host, both in vitro and in vivo. The ease with which S. typhimurium can be cultivated and genetically manipulated, in combination with the availability of tissue culture models and animal models, has made S. typhimurium a desirable organism for such studies. In this review, we focus on Salmonella interactions with its host cells, both in tissue culture (in vitro) and in relevant animal models (in vivo), and compare results obtained using these different models. The recent advent of sophisticated imaging and molecular genetic tools has facilitated studying the events that occur in disease, thereby confirming tissue culture results, yet identifying new questions that need to be addressed in relevant disease settings. 相似文献
79.
80.
Eric W. Ainscough Andrew M. Brodie William A. Denny Graeme J. Finlay John D. Ranford 《Journal of inorganic biochemistry》1998,70(3-4):175-185
The preparation of N-, S- and O-donor ligand adducts with CuX+(HX=6-methyl-2-formylpyridinethiosemicarbazone (6HL); 2-formylpyridine-2′-methylthiosemicarbazone (2′L); 2-formylpyridine-4′-methylthiosemicarbazone (4′HL)) is described. The N-donors, 2,2′-bipyridyl (bipy), 4-dimethylaminopyridine (dmap) give the complexes [Cu(6L)(bipy)]PF6, [Cu(6L)(bipy)]Cl·5H2O, [Cu(4′L)(bipy)]PF6, [Cu(6L)(dmap)2]PF6·2.5 H2O and [Cu(4′L)(dmap)2]PF6·H2O which have been characterized by physical and spectroscopic techniques. Pentafluorothiophenolate (pftp) gives S-donor complexes [CuX(pftp)] (X=6L and 4′L) and thiolato co-ordination is proposed on the basis of spectroscopic evidence. Paratritylphenolate (ptp) and HPO2−4 give O-donor complexes [Cu(6L)(ptp)], [Cu(4′L)(ptp)], [{Cu(6L)}2HPO4]·4H2O, and [{Cu(4′L)}2HPO4]·5H2O which have been characterized by physical and spectroscopic techniques, as have the precursor complexes [Cu(6L)(CH3COO)]·H2O, [Cu(4′L)(CH3COO)], Cu(6HL)(CF3COO)](CF3COO)·0.5H2O, [Cu(4′HL)(CF3COO)](CF3COO), [Cu(2′L)Cl2] and [Cu(2′L)(NO3)2]. Protonation constants for the ligands and some of their complexes have been determined. 2-Formylpyridinethiosemicarbazone (HL) complexes of silver, gold, zinc, mercury, cadmium and lead are also discussed. Cytotoxicity against the human tumor cell line HCT-8 and antiviral data for selected compounds are presented. 相似文献