全文获取类型
收费全文 | 3042篇 |
免费 | 192篇 |
专业分类
3234篇 |
出版年
2023年 | 22篇 |
2022年 | 41篇 |
2021年 | 76篇 |
2020年 | 47篇 |
2019年 | 68篇 |
2018年 | 84篇 |
2017年 | 63篇 |
2016年 | 99篇 |
2015年 | 156篇 |
2014年 | 185篇 |
2013年 | 183篇 |
2012年 | 243篇 |
2011年 | 204篇 |
2010年 | 140篇 |
2009年 | 108篇 |
2008年 | 151篇 |
2007年 | 154篇 |
2006年 | 133篇 |
2005年 | 120篇 |
2004年 | 118篇 |
2003年 | 113篇 |
2002年 | 106篇 |
2001年 | 27篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 34篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 25篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1976年 | 9篇 |
1974年 | 8篇 |
1973年 | 15篇 |
1971年 | 9篇 |
1966年 | 8篇 |
排序方式: 共有3234条查询结果,搜索用时 15 毫秒
71.
Integrated requirement of non‐specific and sequence‐specific DNA binding in Myc‐driven transcription
72.
73.
74.
75.
Mário S. Diniz Hugo M. Santos Pedro M. Costa Isabel Peres Maria H. Costa José L. Capelo 《Biomarkers》2013,18(6):589-598
The main objective of this work was to evaluate arsenic effects on metallothionein (MT) induction by exposing a freshwater Asiatic clam (Corbicula fluminea) to different concentrations of this metalloid. The presence of MT-like proteins was detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis and compared with a standard rabbit MT. In addition, the polarographic response showed good correspondence between standard MT and MT-like curves from C. fluminea, allowing MT quantification. The results show that clams exposed to different concentrations of arsenic are able to induce significant levels of MTs. Although variability was found in MT induction, significant differences in MT levels were found after 28 days of exposure in all treatments in comparison with the controls, suggesting that exposure to arsenic induced MT-like proteins in C. fluminea. 相似文献
76.
Hugo Mélida Jose V. Sandoval-Sierra Javier Diéguez-Uribeondo Vincent Bulone 《Eukaryotic cell》2013,12(2):194-203
Some of the most devastating plant and animal pathogens belong to the oomycete class. The cell walls of these microorganisms represent an excellent target for disease control, but their carbohydrate composition is elusive. We have undertaken a detailed cell wall analysis in 10 species from 2 major oomycete orders, the Peronosporales and the Saprolegniales, thereby unveiling the existence of 3 clearly different cell wall types: type I is devoid of N-acetylglucosamine (GlcNAc) but contains glucuronic acid and mannose; type II contains up to 5% GlcNAc and residues indicative of cross-links between cellulose and 1,3-β-glucans; type III is characterized by the highest GlcNAc content (>5%) and the occurrence of unusual carbohydrates that consist of 1,6-linked GlcNAc residues. These 3 cell wall types are also distinguishable by their cellulose content and the fine structure of their 1,3-β-glucans. We propose a cell wall paradigm for oomycetes that can serve as a basis for the establishment of cell wall architectural models and the further identification of cell wall subtypes. This paradigm is complementary to morphological and molecular criteria for taxonomic grouping and provides useful information for unraveling poorly understood cell wall carbohydrate biosynthetic pathways through the identification and characterization of the corresponding enzymes. 相似文献
77.
Per E. Gustafsson Miguel San Sebastian Urban Janlert T?res Theorell Hugo Westerlund Anne Hammarstr?m 《PloS one》2013,8(11)
Background
Numerous cross-sectional studies have examined neighborhood effects on health. Residential selection in adulthood has been stressed as an important cause of selection bias but has received little empirical attention, particularly its determinants from the earlier life course. The present study aims to examine whether neighborhood, family, school, health behaviors and health in adolescence are related to socioeconomic disadvantage of one''s neighborhood of residence in adulthood.Methods
Based on the prospective Northern Swedish Cohort (analytical N = 971, 90.6% retention rate), information was collected at age 16 years concerning family circumstances, school adjustment, health behaviors and mental and physical health. Neighborhood register data was linked to the cohort and used to operationalize aggregated measures of neighborhood disadvantage (ND) at age 16 and 42. Data was analyzed with linear mixed models, with ND in adulthood regressed on adolescent predictors and neighborhood of residence in adolescence as the level-2 unit.Results
Neighborhood disadvantage in adulthood was clustered by neighborhood of residence in adolescence (ICC = 8.6%). The clustering was completely explained by ND in adolescence. Of the adolescent predictors, ND (b = .14 (95% credible interval = .07–.22)), final school marks (b = −.18 (−.26–−.10)), socioeconomic disadvantage (b = .07 (.01–.14)), and, with borderline significance, school peer problems (b = .07 (−.00–.13)), were independently related to adulthood ND in the final adjusted model. In sex-stratified analyses, the most important predictors were school marks (b = −.21 (−.32–−.09)) in women, and neighborhood of residence (ICC = 15.5%) and ND (b = .20 (.09–.31)) in men.Conclusions
These findings show that factors from adolescence – which also may impact on adult health – could influence the neighborhood context in which one will live in adulthood. This indicates that residential selection bias in neighborhood effects on health research may have its sources in early life. 相似文献78.
Hugo R. Henriques Eline V. Rampazo Antonio J. S. Gon?alves Elaine C. M. Vicentin Jaime H. Amorim Raquel H. Panatieri Kelly N. S. Amorim Marcio M. Yamamoto Luís C. S. Ferreira Ada M. B. Alves Silvia B. Boscardin 《PLoS neglected tropical diseases》2013,7(7)
Dengue is the most prevalent arboviral infection, affecting millions of people every year. Attempts to control such infection are being made, and the development of a vaccine is a World Health Organization priority. Among the proteins being tested as vaccine candidates in preclinical settings is the non-structural protein 1 (NS1). In the present study, we tested the immune responses generated by targeting the NS1 protein to two different dendritic cell populations. Dendritic cells (DCs) are important antigen presenting cells, and targeting proteins to maturing DCs has proved to be an efficient means of immunization. Antigen targeting is accomplished by the use of a monoclonal antibody (mAb) directed against a DC cell surface receptor fused to the protein of interest. We used two mAbs (αDEC205 and αDCIR2) to target two distinct DC populations, expressing either DEC205 or DCIR2 endocytic receptors, respectively, in mice. The fusion mAbs were successfully produced, bound to their respective receptors, and were used to immunize BALB/c mice in the presence of polyriboinosinic: polyribocytidylic acid (poly (I:C)), as a DC maturation stimulus. We observed induction of strong anti-NS1 antibody responses and similar antigen binding affinity irrespectively of the DC population targeted. Nevertheless, the IgG1/IgG2a ratios were different between mouse groups immunized with αDEC-NS1 and αDCIR2-NS1 mAbs. When we tested the induction of cellular immune responses, the number of IFN-γ producing cells was higher in αDEC-NS1 immunized animals. In addition, mice immunized with the αDEC-NS1 mAb were significantly protected from a lethal intracranial challenge with the DENV2 NGC strain when compared to mice immunized with αDCIR2-NS1 mAb. Protection was partially mediated by CD4+ and CD8+ T cells as depletion of these populations reduced both survival and morbidity signs. We conclude that targeting the NS1 protein to the DEC205+ DC population with poly (I:C) opens perspectives for dengue vaccine development. 相似文献
79.
80.