全文获取类型
收费全文 | 2120篇 |
免费 | 171篇 |
出版年
2023年 | 16篇 |
2022年 | 43篇 |
2021年 | 88篇 |
2020年 | 40篇 |
2019年 | 47篇 |
2018年 | 49篇 |
2017年 | 48篇 |
2016年 | 80篇 |
2015年 | 116篇 |
2014年 | 122篇 |
2013年 | 155篇 |
2012年 | 193篇 |
2011年 | 169篇 |
2010年 | 109篇 |
2009年 | 89篇 |
2008年 | 116篇 |
2007年 | 115篇 |
2006年 | 131篇 |
2005年 | 99篇 |
2004年 | 86篇 |
2003年 | 60篇 |
2002年 | 58篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1986年 | 10篇 |
1985年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1973年 | 5篇 |
1971年 | 7篇 |
1968年 | 3篇 |
1963年 | 3篇 |
1932年 | 2篇 |
1924年 | 2篇 |
排序方式: 共有2291条查询结果,搜索用时 390 毫秒
81.
Xolalpa W Vallecillo AJ Lara M Mendoza-Hernandez G Comini M Spallek R Singh M Espitia C 《Proteomics》2007,7(18):3332-3341
Binding and activation of human plasminogen (Plg) to generate the proteolytic enzyme plasmin (Plm) have been associated with the invasive potential of certain bacteria. In this work, proteomic analysis together with ligand blotting assays identified several major Plg-binding spots in Mycobacterium tuberculosis soluble extracts (SEs) and culture filtrate proteins. The identity of 15 different proteins was deduced by N-terminal and/or MS and corresponded to DnaK, GroES, GlnA1, Ag85 complex, Mpt51, Mpt64, PrcB, MetK, SahH, Lpd, Icl, Fba, and EF-Tu. Binding of Plg to recombinant M. tuberculosis DnaK, GlnA1, and Ag85B was further confirmed by ELISA and ligand blotting assays. The binding was inhibited by epsilon-aminocaproic acid, indicating that the interaction involved lysine residues. Plg bound to recombinant mycobacterial proteins was activated to Plm by tissue-type Plg activator. In contrast with recombinant proteins, M. tuberculosis SE enhanced several times the Plg activation mediated by the activator. Interestingly, GlnA1 was able to bind the extracellular matrix (ECM) protein fibronectin. Together these results show that M. tuberculosis posses several Plg receptors suggesting that bound Plg to bacteria surface, can be activated to Plm, endowing bacteria with the ability to break down ECM and basal membranes proteins contributing to tissue injury in tuberculosis. 相似文献
82.
Draisci R Montesissa C Santamaria B D'Ambrosio C Ferretti G Merlanti R Ferranti C De Liguoro M Cartoni C Pistarino E Ferrara L Tiso M Scaloni A Cosulich ME 《Proteomics》2007,7(17):3184-3193
Surveillance of illegal use of steroids hormones in cattle breeding is a key issue to preserve human health. To this purpose, an integrated approach has been developed for the analysis of plasma and urine from calves treated orally with a single dose of a combination of the androgenic steroids boldenone and boldione. A quantitative estimation of steroid hormones was obtained by LC-APCI-Q-MS/MS analysis of plasma and urine samples obtained at various times up to 36 and 24 h after treatment, respectively. These experiments demonstrated that boldione was never found, while boldenone alpha- and beta-epimers were detected in plasma and urine only within 2 and 24 h after drug administration, respectively. Parallel proteomic analysis of plasma samples was obtained by combined 2-DE, MALDI-TOF-MS and muLC-ESI-IT-MS/MS procedures. A specific protein, poorly represented in normal plasma samples collected before treatment, was found upregulated even 36 h after hormone treatment. Extensive mass mapping experiments proved this component as an N-terminal truncated form of apolipoprotein A1 (ApoA1), a protein involved in cholesterol transport. The expression profile of ApoA1 analysed by Western blot analysis confirmed a significant and time dependent increase of this ApoA1 fragment. Then, provided that further experiments performed with a growth-promoting schedule will confirm these preliminary findings, truncated ApoA1 may be proposed as a candidate biomarker for steroid boldenone and possibly other anabolic androgens misuse in cattle veal calves, when no traces of hormones are detectable in plasma or urine. 相似文献
83.
We studied the composition, species richness, and relative abundance of bat assemblages in the Colombian dry forests of Chicamocha and Patía. In Chicamocha, 11 bats of the family Phyllostomidae were captured with mist-nets, corresponding to 85–100% of the potential phyllostomids species in the area. Two bats of the family Vespertilionidae were also captured in Chicamocha. In Patía, 12 species were captured with mist-nets, all Phyllostomidae, representing 72–100% of the estimated total number of species in the zone. Minor differences in number of species and composition were detected among sampling periods in Chicamocha. The most common species in this dry forest were Glossophaga longirostris and Sturnira lilium. In Patía, notable differences in the number of species and composition were observed among sampling periods, and the most common species were Artibeus jamaicensis, Carollia perspicillata and Phyllostomus discolor. Arid-zone dwelling bats were absent in Patía and we suggest that this absence may be associated with the isolation of Patía from other northern dry zones of Colombia since Quaternary times. There was also low abundance of bats in Patía, which appears to be related to human disturbance. The most abundant phyllostomid bat species in the two dry forests studied are those that include fruit and/or nectar-pollen from columnar cacti as an important proportion of their diets. 相似文献
84.
Recombinant BCG vaccine candidates 总被引:1,自引:0,他引:1
Given the variable protective efficacy provided by Mycobacterium bovis BCG (Bacillus Calmette-Guérin), there is a concerted effort worldwide to develop better vaccines that could be used to reduce the burden of tuberculosis. Recombinant BCG (rBCG) are vaccine candidates that offer some potential in this area. In this paper, we will discuss the molecular methods used to generate rBCG, and the results obtained with some of these new vaccines as compared with the conventional BCG vaccine in diverse animal models. Tuberculosis vaccine candidates based on rBCG are promising candidates, and some of them are now being tested in clinical trials. 相似文献
85.
Andrea-Anneliese Keller Berith Scheiding Reinhard Breitling Andreas Licht Peter Hemmerich Stefan Lorkowski Siegmund Reissmann 《Journal of cellular biochemistry》2019,120(1):14-27
Cell-penetrating peptides (CPPs) are used to internalize different cargoes, including DNA, into live mammalian and plant cells. Despite many cells being easily transfected with this approach, other cells are rather “difficult” or “hard to transfect,” including protist cells of the genus Leishmania. Based on our previous results in successfully internalizing proteins into Leishmania tarentolae cells, we used single CPPs and three different DNA-binding proteins to form protein-like complexes with plasmids covered with CPPs. We attempted magnetofection, electroporation, and transfection using a number of commercially available detergents. While complex formation with negatively charged DNA required substantially higher amounts of CPPs than those necessary for mostly neutral proteins, the cytotoxicity of the required amounts of CPPs and auxiliaries was thoroughly studied. We found that Leishmania cells were indeed susceptible to high concentrations of some CPPs and auxiliaries, although in a different manner compared with that for mammalian cells. The lack of successful transfections implies the necessity to accept certain general limitations regarding DNA internalization into difficult-to-transfect cells. Only electroporation allowed reproducible internalization of large and rigid plasmid DNA molecules through electrically disturbed extended membrane areas, known as permeable membrane macrodomains. 相似文献
86.
87.
Clara R. Burgert-Brucker Molly W. Adams Pia Mingkwan Rebecca Flueckiger Jeremiah M. Ngondi Anthony W. Solomon Emma M. Harding-Esch 《PLoS neglected tropical diseases》2022,16(4)
BackgroundTrachoma is targeted for global elimination as a public health problem by 2030. Understanding individual, household, or community-associated factors that may lead to continued transmission or risk of recrudescence in areas where elimination has previously been achieved, is essential in reaching and maintaining trachoma elimination. We aimed to identify climatic, demographic, environmental, infrastructural, and socioeconomic factors associated in the literature with trachoma at community-level and assess the strength of their association with trachoma. Because of the potential power of geospatial analysis to delineate the variables most strongly associated with differences in trachoma prevalence, we then looked in detail at geospatial analysis methods used in previous trachoma studies.MethodsWe conducted a systematic literature review using five databases: Medline, Embase, Global Health, Dissertations & Theses Global, and Web of Science, including publications from January 1950 to January 2021. The review protocol was prospectively registered with PROSPERO (CRD42020191718).ResultsOf 35 eligible studies, 29 included 59 different trachoma-associated factors, with eight studies also including spatial analysis methods. Six studies included spatial analysis methods only. Higher trachomatous inflammation—follicular (TF) prevalence was associated with areas that: had lower mean annual precipitation, lower mean annual temperatures, and lower altitudes; were rural, were less accessible, had fewer medical services, had fewer schools; and had lower access to water and sanitation. Higher trachomatous trichiasis (TT) prevalence was associated with higher aridity index and increased distance to stable nightlights. Of the 14 studies that included spatial methods, 11 used exploratory spatial data analysis methods, three used interpolation methods, and seven used spatial modelling methods.ConclusionResearchers and decision-makers should consider the inclusion and potential influence of trachoma-associated factors as part of both research activities and programmatic priorities. The use of geospatial methods in trachoma studies remains limited but offers the potential to define disease hotspots and areas of potential recrudescence to inform local, national, and global programmatic needs. 相似文献
88.
89.
Chronic granulomatous disease (CGD) is a rare inherited disorder in which phagocytes lack NADPH oxidase activity. The most common form is caused by mutations in the CYBB gene encoding gp91phox protein, the heavy chain of cytochrome b558, which is the redox element of NADPH oxidase. In some rare cases, the mutated gp91phox is normally expressed but no NADPH oxidase can be detected. This type of CGD is called X91+ CGD. We have previously reported an X+ CGD case with a double-missense mutation in gp91phox. Transgenic PLB-985 cells have now been made to study the impact of each single mutation on oxidase activity and assembly to rule out a possible new polymorphism in the CYBB gene. The His303Asn/Pro304Arg gp91phox transgenic PLB-985 cells exactly mimic the phenotype of the neutrophils of the X+ CGD patient. The His303Asn mutation is sufficient to inhibit oxidase activity in intact cells and in a broken cell system, whereas in the Pro304Arg mutant, residual activity suggests that the Pro304Arg substitution is less devastating to oxidase activity than the His303Asn mutation. The study of NADPH oxidase assembly following the in vitro and in vivo translocation of cytosolic factors p47phox and p67phox has demonstrated that, in the double mutant and in the His303Asn mutant, NADPH oxidase assembly is abolished, although the translocation is only attenuated in Pro304Arg mutant cells. Thus, even though the His303Asn mutation has a more severe inhibitory effect on NADPH oxidase activity and assembly than the Pro304Arg mutation, neither mutation can be considered as a polymorphism.Clara Bionda and Xing Jun Li contributed equally to this work 相似文献
90.
Marcello Tonelli Brenda Hemmelgarn Braden Manns George Pylypchuk Clara Bohm Karen Yeates Sita Gourishankar John S. Gill 《CMAJ》2004,171(6):577-582