全文获取类型
收费全文 | 2395篇 |
免费 | 336篇 |
国内免费 | 1篇 |
专业分类
2732篇 |
出版年
2022年 | 15篇 |
2021年 | 30篇 |
2020年 | 23篇 |
2019年 | 23篇 |
2018年 | 35篇 |
2017年 | 23篇 |
2016年 | 57篇 |
2015年 | 91篇 |
2014年 | 122篇 |
2013年 | 118篇 |
2012年 | 116篇 |
2011年 | 117篇 |
2010年 | 95篇 |
2009年 | 83篇 |
2008年 | 110篇 |
2007年 | 117篇 |
2006年 | 73篇 |
2005年 | 94篇 |
2004年 | 97篇 |
2003年 | 97篇 |
2002年 | 99篇 |
2001年 | 88篇 |
2000年 | 84篇 |
1999年 | 67篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 37篇 |
1995年 | 35篇 |
1994年 | 37篇 |
1993年 | 31篇 |
1992年 | 66篇 |
1991年 | 59篇 |
1990年 | 45篇 |
1989年 | 54篇 |
1988年 | 40篇 |
1987年 | 26篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 23篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 18篇 |
1975年 | 18篇 |
1974年 | 17篇 |
1973年 | 14篇 |
1972年 | 11篇 |
1968年 | 13篇 |
排序方式: 共有2732条查询结果,搜索用时 15 毫秒
81.
Michele Tinti Lars Kiemer Stefano Costa Martin L. Miller Francesca Sacco Jesper V. Olsen Martina Carducci Serena Paoluzi Francesca Langone Christopher T. Workman Nikolaj Blom Kazuya Machida Christopher M. Thompson Mike Schutkowski Søren Brunak Matthias Mann Bruce J. Mayer Luisa Castagnoli Gianni Cesareni 《Cell reports》2013,3(4):1293-1305
Highlights? The recognition specificity of 70 SH2 domains is probed ? Recognition specificity diverges faster than sequence ? PepspotDB is a database of protein interactions mediated by SH2 domains 相似文献
82.
Simon Glerup Maria Lume Ditte Olsen Jens R. Nyengaard Christian B. Vaegter Camilla Gustafsen Erik I. Christensen Mads Kjolby Anders Hay-Schmidt Dirk Bender Peder Madsen Mart Saarma Anders Nykjaer Claus M. Petersen 《Cell reports》2013,3(1):186-199
Highlights? SorLA is a sorting receptor for GDNF and its signaling receptors GFRa1 and RET ? The SorLA/GFRa1 complex targets GDNF for lysosomal degradation, while GFRa1 is recycled ? SorLA/GFRa1 targets RET for endocytosis and influences GDNF-induced neurotrophic effects ? SorLA knockout mice display altered dopaminergic function and an ADHD-like phenotype 相似文献
83.
Genotype‐environment associations support a mosaic hybrid zone between two tidal marsh birds 下载免费PDF全文
Jennifer Walsh Rebecca J. Rowe Brian J. Olsen W. Gregory Shriver Adrienne I. Kovach 《Ecology and evolution》2016,6(1):279-294
Local environmental features can shape hybrid zone dynamics when hybrids are bounded by ecotones or when patchily distributed habitat types lead to a corresponding mosaic of genotypes. We investigated the role of marsh‐level characteristics in shaping a hybrid zone between two recently diverged avian taxa – Saltmarsh (Ammodramus caudacutus) and Nelson's (A. nelsoni) sparrows. These species occupy different niches where allopatric, with caudacutus restricted to coastal marshes and nelsoni found in a broader array of wetland and grassland habitats and co‐occur in tidal marshes in sympatry. We determined the influence of habitat types on the distribution of pure and hybrid sparrows and assessed the degree of overlap in the ecological niche of each taxon. To do this, we sampled and genotyped 305 sparrows from 34 marshes across the hybrid zone and from adjacent regions. We used linear regression to test for associations between marsh characteristics and the distribution of pure and admixed sparrows. We found a positive correlation between genotype and environmental variables with a patchy distribution of genotypes and habitats across the hybrid zone. Ecological niche models suggest that the hybrid niche was more similar to that of A. nelsoni and habitat suitability was influenced strongly by distance from coastline. Our results support a mosaic model of hybrid zone maintenance, suggesting a role for local environmental features in shaping the distribution and frequency of pure species and hybrids across space. 相似文献
84.
Chiung-Kuei Huang Yoshifumi Iwagami Arihiro Aihara Waihong Chung Suzanne de la Monte John-Michael Thomas Mark Olsen Rolf Carlson Tunan Yu Xiaoqun Dong Jack Wands 《PloS one》2016,11(3)
Cholangiocarcinoma (CCA) has a poor prognosis due to widespread intrahepatic spread. Aspartate β-hydroxylase (ASPH) is a transmembrane protein and catalyzes the hydroxylation of aspartyl and asparaginyl residues in calcium binding epidermal growth factor (cbEGF)-like domains of various proteins, including Notch receptors and ligands. ASPH is highly overexpressed (>95%) in human CCA tumors. We explored the molecular mechanisms by which ASPH mediated the CCA malignant phenotype and evaluated the potential of ASPH as a therapeutic target for CCA. The importance of expression and enzymatic activity of ASPH for CCA growth and progression was examined using shRNA “knockdown” and a mutant construct that reduced its catalytic activity. Second generation small molecule inhibitors (SMIs) of β-hydroxylase activity were developed and used to target ASPH in vitro and in vivo. Subcutaneous and intrahepatic xenograft rodent models were employed to determine anti-tumor effects on CCA growth and development. It was found that the enzymatic activity of ASPH was critical for mediating CCA progression, as well as inhibiting apoptosis. Mechanistically, ASPH overexpression promoted Notch activation and modulated CCA progression through a Notch1-dependent cyclin D1 pathway. Targeting ASPH with shRNAs or a SMI significantly suppressed CCA growth in vivo. 相似文献
85.
Yakovlev Igor A. Carneros Elena Lee YeonKyeong Olsen Jorunn E. Fossdal Carl Gunnar 《Planta》2016,243(5):1237-1249
Planta - A significant number of epigenetic regulators were differentially expressed during embryogenesis at different epitype-inducing conditions. Our results support that methylation of DNA and... 相似文献
86.
Grace C. Lee Ronald G. Hall Natalie K. Boyd Steven D. Dallas Liem C. Du Lucina B. Treviño Sylvia B. Treviño Chad Retzloff Kenneth A. Lawson James Wilson Randall J. Olsen Yufeng Wang Christopher R. Frei 《Annals of clinical microbiology and antimicrobials》2016,15(1):58
Background
The incidence of outpatient visits for skin and soft tissue infections (SSTIs) has substantially increased over the last decade. The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has made the management of S. aureus SSTIs complex and challenging. The objective of this study was to identify risk factors contributing to treatment failures associated with community-associated S. aureus skin and soft tissue infections SSTIs.Methods
This was a prospective, observational study among 14 primary care clinics within the South Texas Ambulatory Research Network. The primary outcome was treatment failure within 90 days of the initial visit. Univariate associations between the explanatory variables and treatment failure were examined. A generalized linear mixed-effect model was developed to identify independent risk factors associated with treatment failure.Results
Overall, 21% (22/106) patients with S. aureus SSTIs experienced treatment failure. The occurrence of treatment failure was similar among patients with methicillin-resistant S. aureus and those with methicillin-susceptible S. aureus SSTIs (19 vs. 24%; p = 0.70). Independent predictors of treatment failure among cases with S. aureus SSTIs was a duration of infection of ≥7 days prior to initial visit [aOR, 6.02 (95% CI 1.74–19.61)] and a lesion diameter size ≥5 cm [5.25 (1.58–17.20)].Conclusions
Predictors for treatment failure included a duration of infection for ≥7 days prior to the initial visit and a wound diameter of ≥5 cm. A heightened awareness of these risk factors could help direct targeted interventions in high-risk populations.87.
88.
Even Moland Stephanie M. Carlson David Villegas‐Ríos Jrgen Ree Wiig Esben Moland Olsen 《Ecology and evolution》2019,9(11):6480-6491
Harvesting can have profound impacts on the ecology and evolution of marine populations. However, little is known about the strength and direction of fisheries‐induced selection acting on multiple traits in the wild. Here, we used acoustic telemetry to directly monitor individual behavior and fate in an intensively harvested species, the European lobster (Homarus gammarus, n = 100), in southern Norway. Overall, 24% of the tracked lobsters survived the two‐month harvest season within the study area. Our results indicated that local survival was not random with respect to phenotype. We found no clear support for fisheries‐induced selection acting directly on body size. However, lobsters with large crusher claws relative to their body size, typical of socially dominant individuals, appeared at higher risk of being captured in the conventional trap fishery. We also detected a fine‐scale spatial gradient in survival. After accounting for this gradient, individuals displaying larger home ranges were more likely to survive the harvest season. Finally, we found significant repeatabilities for lobster behavior on a monthly timescale, indicating that individual behavioral attributes tended to persist and may reflect personality. Our study therefore provides empirical support for the need to consider an evolutionary enlightened approach to fisheries management that considers the influence of harvest on multiple traits of target species. 相似文献
89.
Objective: Our aim was to examine whether secular trends in childhood overweight and obesity during five decades could be explained by economic growth. Research Methods and Procedures: Annual measurements of height and weight were available for all children born between 1930 and 1983 attending primary school in the Copenhagen Municipality: 165,389 boys and 163,609 girls from the age of 7 through 13 years. After computerization, we calculated BMI (kg/m2) and estimated the prevalence of overweight and obesity, according to international age‐ and gender‐specific criteria, by year of birth and of measurement, and separately by each age group and gender. Economic growth was indicated by the Gross National Product and the overall consumption per capita, adjusted for inflation. Results: The prevalence of overweight occurred in phases: an increase from 1930 until the 1950s, followed by a plateau period between the 1950s and the 1960s and a steep increase thereafter. This pattern was apparent across all age groups and in both genders. Obesity trends showed a similar phase pattern; the prevalence remained relatively stable from 1930 until the 1940s, increased until the mid‐1950s, followed by a plateau until 1965, and thereafter a second steep increase. Obesity trends were similar among boys across all age groups, although only among girls from 11 to 13 years of age. In both genders, increments were most pronounced in the upper BMI percentiles. After stagnation until 1947, the economic growth indicators showed a steady increase; i.e., after the first increase started in overweight and obesity, whether analyzed by year of birth or year of measurement, there were no indications of phases in the rise thereafter. Discussion: Prevalence of overweight and obesity among Danish children rose in phases, which were not paralleled by trends in economic growth. The macroeconomic growth indicators seem inappropriate as proxies for the environmental exposures that have elicited the obesity epidemic. 相似文献
90.
Synaptic vesicles dock to the plasma membrane at synapses to facilitate rapid exocytosis. Docking was originally proposed to require the soluble N-ethylmaleimide–sensitive fusion attachment protein receptor (SNARE) proteins; however, perturbation studies suggested that docking was independent of the SNARE proteins. We now find that the SNARE protein syntaxin is required for docking of all vesicles at synapses in the nematode Caenorhabditis elegans . The active zone protein UNC-13, which interacts with syntaxin, is also required for docking in the active zone. The docking defects in unc-13 mutants can be fully rescued by overexpressing a constitutively open form of syntaxin, but not by wild-type syntaxin. These experiments support a model for docking in which UNC-13 converts syntaxin from the closed to the open state, and open syntaxin acts directly in docking vesicles to the plasma membrane. These data provide a molecular basis for synaptic vesicle docking. 相似文献