首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   673篇
  免费   120篇
  国内免费   13篇
  2024年   6篇
  2023年   45篇
  2022年   48篇
  2021年   58篇
  2020年   49篇
  2019年   55篇
  2018年   32篇
  2017年   30篇
  2016年   27篇
  2015年   31篇
  2014年   53篇
  2013年   49篇
  2012年   33篇
  2011年   43篇
  2010年   19篇
  2009年   30篇
  2008年   28篇
  2007年   26篇
  2006年   16篇
  2005年   16篇
  2004年   18篇
  2003年   12篇
  2002年   10篇
  2001年   8篇
  2000年   12篇
  1999年   1篇
  1998年   3篇
  1997年   7篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1993年   7篇
  1992年   1篇
  1991年   2篇
  1990年   3篇
  1988年   1篇
  1987年   2篇
  1985年   3篇
  1984年   5篇
  1983年   3篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1978年   1篇
  1977年   2篇
排序方式: 共有806条查询结果,搜索用时 19 毫秒
771.
Missense variants are alterations to protein coding sequences that result in amino acid substitutions. They can be deleterious if the amino acid is required for maintaining structure or/and function, but are likely to be tolerated at other sites. Consequently, missense variation within a healthy population can mirror the effects of negative selection on protein structure and function, such that functional sites on proteins are often depleted of missense variants. Advances in high-throughput sequencing have dramatically increased the sample size of available human variation data, allowing for population-wide analysis of selective pressures. In this study, we developed a convenient set of tools, called 1D-to-3D, for visualizing the positions of missense variants on protein sequences and structures. We used these tools to characterize human homologues of the ARID family of gene regulators. ARID family members are implicated in multiple cancer types, developmental disorders, and immunological diseases but current understanding of their mechanistic roles is incomplete. Combined with phylogenetic and structural analyses, our approach allowed us to characterise sites important for protein-protein interactions, histone modification recognition, and DNA binding by the ARID proteins. We find that comparing missense depletion patterns among paralogs can reveal sub-functionalization at the level of domains. We propose that visualizing missense variants and their depletion on structures can serve as a valuable tool for complementing evolutionary and experimental findings.  相似文献   
772.
773.
《Endocrine practice》2022,28(11):1118-1124
ObjectiveThis study aimed to determine the clinical indicators influencing bone mineral density (BMD) of the lumbar spine and femoral neck in patients with pituitary stalk interruption syndrome (PSIS) who underwent multiple hormone replacement therapy (MHRT).MethodsMale patients with PSIS (n = 51) who underwent MHRT for at least 1 year were enrolled in this study. Their BMD parameters were recorded and compared with age-, weight-, and height-matched control adults. In addition, we performed multiple linear regression analysis to correlate clinical parameters with BMD parameters at 2 different sites.ResultsFifty-one patients with PSIS had a mean age of 30.39 ± 5.50 years. After 36 months of treatment, patients with PSIS who underwent MHRT had slightly lower BMD than those in the control group. Multiple linear regression models revealed a positive association between the Z-score values for the lumbar spine with treatment duration (r = 0.453, P < .001), insulin-like growth factor-1 (IGF-1) standard deviation score (SDS) values (r = 0.248, P = .038), and total testosterone level (r = 0.260, P = .036) and a positive association between the Z-score values for the femoral neck with treatment duration (r = 0.425, P < .001) and IGF-1 SDS values (r = 0.338, P = .009).ConclusionCollectively, long-term MHRT improves bone density in patients with PSIS to the normal range. A combination of recombinant human growth hormone replacement is more beneficial to the BMD than non–recombinant human growth hormone treatment. Moreover, serum IGF-1 contributes to femoral and lumbar mineralization, whereas serum testosterone plays a role in lumbar mineralization.  相似文献   
774.
Superoxide dismutases (SODs) are metalloproteins that protect cells against oxidative stress by controlling the concentration of superoxide (O2) through catalysis of its dismutation. The activity of superoxide dismutases can be mimicked by low-molecular-weight complexes having potential therapeutic applications. This review presents recent strategies for designing efficient SOD mimics, from molecular metal complexes to nanomaterials. Studies of these systems in cells reveal that some SOD mimics, designed to react directly with superoxide, may also indirectly enhance the cellular antioxidant arsenal. Finally, a good understanding of the bioactivity requires information on the cell-penetration, speciation, and subcellular location of the SOD mimics: we will describe recent studies and new techniques that open opportunities for characterizing SOD mimics in biological environments.  相似文献   
775.
P G Goicoechea  R J Petit  A Kremer 《Heredity》2012,109(6):361-371
Genome scans are increasingly used to study ecological speciation, providing a useful genome-wide perspective on divergent selection in the presence of gene flow. Here, we compare current approaches to detect footprints of divergent selection in closely related species. We analyzed 192 individuals from two interfertile European temperate oak species using 30 nuclear microsatellites from eight linkage groups. These markers present little intraspecific differentiation and can be used in combination to assign individual genotypes to species. We first show that different outlier detection tests give somewhat different results, possibly due to model constraints. Second, using linkage information for these markers, we further characterize the signature of divergent selection in the presence of gene flow. In particular, we show that recombination estimates for regions with outlier markers are lower than those for a control region, in line with a prediction from ecological speciation theory. Most importantly, we show that analyses at the haplotype level can distinguish between truly divergent (bi-directional) selection and positive selection in one of the two species, offering a new and improved method for characterizing the speciation process.  相似文献   
776.
Human values and personality have been shown to share genetic variance in twin studies. However, there is a lack of evidence about the genetic components of this association. This study examined the interplay between genes, values and personality in the case of neuroticism, because polygenic scores were available for this personality trait. First, we replicated prior evidence of a positive association between the polygenic neuroticism score (PNS) and neuroticism. Second, we found that the PNS was significantly associated with the whole human value space in a sinusoidal waveform that was consistent with Schwartz's circular model of human values. These results suggest that it is useful to consider human values in the analyses of genetic contributions to personality traits. They also pave the way for an investigation of the biological mechanisms contributing to human value orientations.  相似文献   
777.
《Endocrine practice》2022,28(11):1152-1158
ObjectiveTo evaluate the effects of diabetes and hyperglycemia on in-hospital mortality in critically ill patients older than 75 years.MethodsThis was a single-center retrospective cohort study of patients older than 75 years in the first intensive care unit stay. The patients were divided into the following 4 groups: time-weighted average glucose (TWAG) <140 mg/dL without diabetes (group 1), TWAG ≥140 mg/dL without diabetes (group 2), TWAG <180 mg/dL with diabetes (group 3), and TWAG ≥180 mg/dL with diabetes (group 4). Clinical and laboratory data were analyzed.ResultsA total of 6760 patients over 75 years of age were included, including 2089 patients previously diagnosed with diabetes. The patients in group 2 had the highest in-hospital mortality (27.4%). In the fully adjusted regression model, the risk of in-hospital mortality increased by 76% (odds ratio = 1.76, 95% CI: 1.49-2.08) in group 2 as compared with group 1. Those from groups 3 and 4 exhibited risks equivalent to the risks of those in group 1; similar results were observed in the subgroup analysis. A J-shaped curve relationship and threshold effect were observed in patients without diabetes. For those with diabetes, a flatter curve pattern with a small slope was observed.ConclusionStress hyperglycemia was more detrimental to short-term prognosis than diabetes status in these patients. Looser glucose control may be suitable for patients older than 75 years with diabetes but unnecessary for those without diabetes. Patients with diabetes may be more resistant to the detrimental effects of glucose variations.  相似文献   
778.
《Endocrine practice》2021,27(3):245-253
ObjectiveTo examine risk factors that might be associated with thyroid eye disease (TED) in patients with Graves’ disease (GD), which may guide physicians in the prevention and management of TED.MethodsMedline and Embase were searched for articles discussing risk factors of TED. Comparisons were made between GD patients with and without TED, and between active and inactive TED GD patients. Weighted mean differences (WMDs) and odds ratios (ORs) were determined for continuous and dichotomous outcomes, respectively. Results were pooled with random effects using the DerSimonian and Laird model.ResultsFifty-six articles were included in the analysis. Smoking, inclusive of current and previous smoking status, was a significant risk factor for TED (OR: 2.401; CI: 1.958-2.945; P < .001). Statistical significance was found upon meta-regression between male sex and the odds of smoking and TED (β = 1.195; SE = 0.436; P = .013). Other risk factors were also examined, and patients with TED were significantly older than those without TED (WMD: 1.350; CI: 0.328-2.372; P = .010). While both age (WMD: 5.546; CI: 3.075-8.017; P < .001) and male sex (OR: 1.819; CI: 1.178-2.808; P = .007) were found to be significant risk factors for active TED patients compared to inactive TED patients, no statistical significance was found for family history, thyroid status, cholesterol levels, or body mass index.ConclusionFactors such as smoking, sex, and age predispose GD patients to TED, and TED patients to active TED. A targeted approach in the management of GD and TED is required to reduce the modifiable risk factor of smoking.  相似文献   
779.
Summary : Often clinical studies periodically record information on disease progression as well as results from laboratory studies that are believed to reflect the progressing stages of the disease. A primary aim of such a study is to determine the relationship between the lab measurements and a disease progression. If there were no missing or censored data, these analyses would be straightforward. However, often patients miss visits, and return after their disease has progressed. In this case, not only is their progression time interval censored, but their lab test series is also incomplete. In this article, we propose a simple test for the association between a longitudinal marker and an event time from incomplete data. We derive the test using a very intuitive technique of calculating the expected complete data score conditional on the observed incomplete data (conditional expected score test, CEST). The problem was motivated by data from an observational study of patients with diabetes.  相似文献   
780.
Abstract

Purpose

To validate the IABP-SHOCK II risk score in a Danish cohort and assess the association between the IABP-SHOCK II risk score and admission concentration of biomarkers reflecting neurohormonal – (Copeptin, Pro-atrial natriuretic peptide (proANP), Mid-regional pro-adrenomedullin (MRproADM)) and inflammatory (ST2) activation in patients with CS complicating ST segment elevation myocardial infarction (STEMI).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号