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   4768篇
  免费   294篇
  国内免费   36篇
耳鼻咽喉   64篇
儿科学   122篇
妇产科学   111篇
基础医学   736篇
口腔科学   107篇
临床医学   630篇
内科学   837篇
皮肤病学   93篇
神经病学   621篇
特种医学   195篇
外科学   418篇
综合类   28篇
一般理论   4篇
预防医学   375篇
眼科学   90篇
药学   264篇
中国医学   13篇
肿瘤学   390篇
  2024年   10篇
  2023年   40篇
  2022年   66篇
  2021年   158篇
  2020年   91篇
  2019年   134篇
  2018年   164篇
  2017年   121篇
  2016年   144篇
  2015年   170篇
  2014年   206篇
  2013年   240篇
  2012年   361篇
  2011年   357篇
  2010年   254篇
  2009年   197篇
  2008年   286篇
  2007年   327篇
  2006年   268篇
  2005年   256篇
  2004年   254篇
  2003年   200篇
  2002年   238篇
  2001年   36篇
  2000年   46篇
  1999年   55篇
  1998年   42篇
  1997年   36篇
  1996年   32篇
  1995年   31篇
  1994年   30篇
  1993年   16篇
  1992年   12篇
  1991年   12篇
  1990年   16篇
  1989年   20篇
  1988年   17篇
  1987年   13篇
  1986年   14篇
  1984年   5篇
  1983年   10篇
  1982年   8篇
  1981年   8篇
  1980年   5篇
  1979年   11篇
  1978年   7篇
  1977年   5篇
  1972年   6篇
  1971年   7篇
  1965年   7篇
排序方式: 共有5098条查询结果,搜索用时 15 毫秒
41.
42.
Hypovitaminosis D is prevalent worldwide, and especially in South-Asia. According to the Institute of Medicine (IOM), 25(OH)D levels below 30 nmol/L are defined as vitamin D deficiency (VDD) and levels between 30–50 nmol/L as insufficiency (VDI). Besides its role in calcium homeostasis, it has been postulated that vitamin D is involved in metabolic syndrome. Given the scarcity of data on vitamin D status in Nepal, we aimed to examine the prevalence of VDD and VDI, as well as the determinants and association with metabolic parameters (lipids, HbA1c), in a cohort of women in rural Nepal. Altogether, 733 women 48.5 ± 11.7 years of age were included. VDD and VDI were observed in 6.3 and 42.4% of the participants, respectively, and the prevalence increased by age. Women reporting intake of milk and eggs > 2 times weekly had higher 25(OH)D levels than those reporting intake < 2 times weekly. Women with vitamin D levels < 50 nmol/L displayed higher levels of cholesterol, LDL-cholesterol, triglycerides, and HbA1c. Additionally, a regression analysis showed a significant association between hypovitaminosis D, dyslipidemia, and HbA1c elevation. In conclusion, VDI was prevalent and increased with age. Milk and egg intake > 2 times weekly seemed to decrease the risk of VDI. Moreover, hypovitaminosis D was associated with an adverse metabolic profile.  相似文献   
43.
44.
45.
46.
BRAF V600E is an emerging drug target in lung cancer, but the clinical significance of non-V600 BRAF mutations in lung cancer and other malignancies is less clear. Here, we report the case of a patient with metastatic lung adenocarcinoma with BRAF G469L mutation refractory to vemurafenib. We calculated a structure model of this very rare type of mutated BRAF kinase to explain the molecular mechanism of drug resistance. This information may help to develop effective targeted therapies for cancers with non-V600 BRAF mutations.  相似文献   
47.
In an attempt to identify common disease susceptibility alleles for breast cancer, we performed a combined analysis of three genome-wide association studies (GWAS), involving 2,702 women of European ancestry with invasive breast cancer and 5,726 controls. Tests for association were performed for 285,984 SNPs. Evidence for association with SNPs in genes in specific pathways was assessed using a permutation-based approach. We confirmed associations with loci reported by previous GWAS on 1p11.2, 2q35, 3p, 5p12, 8q24, 10q23.13, 14q24.1 and 16q. Six SNPs with the strongest signals of association with breast cancer, and which have not been reported previously, were typed in two further studies; however, none of the associations could be confirmed. Suggestive evidence for an excess of associations was found for genes involved in the regulation of actin cytoskeleton, glycan degradation, alpha-linolenic acid metabolism, circadian rhythm, hematopoietic cell lineage and drug metabolism. Androgen and oestrogen metabolism, a pathway previously found to be associated with the development of postmenopausal breast cancer, was marginally significant (P = 0.051 [unadjusted]). These results suggest that further analysis of SNPs in these pathways may identify associations that would be difficult to detect through agnostic single SNP analyses. More effort focused in these aspects of oncology can potentially open up promising avenues for the understanding of breast cancer and its prevention.  相似文献   
48.

Background  

To analyze whether epidermal growth factor (EGF) exerts regulatory effects on proliferation and differentiation in ARPE19 cells after different incubation periods (24 vs. 48 h) for obtaining ideal conditions for feasible rejuvenation and autologous transplantation of retinal pigment epithelial cells (RPE cells).  相似文献   
49.
Methods. Three-month-old female Wistar rats were fed with 20% alcohol in their drinking fluid over 6–17 mo using an interrupted feeding regimen. At different times, pancreatic acini were isolated by mild collagenase digestion. The concentrations of inositol-1,4,5-trisphosphate (1,4,5-IP3) were determined by a specific radioreceptor assay, before and at different times after stimulation with varying concentrations of CCK-8. CCK-induced dynamics of cytoplasmic calcium ([Ca2+]c) was investigated in acinar cells by confocal laser raster microscopy. Acinar α-amylase (Aml) secretion was measured as enzyme activity in the medium compared to the total activity in the suspension. Results. In 12–13-mo-old rats, the CCK-stimulated 1,4,5-IP3 formation in acini was found to be decreased compared to young rats (age 4 mo). In rats of the same age fed with ethanol from the age of 3 mo on, 1,4,5-IP3 concentrations in acini were higher and reached values comparable to those in young rats. Corre-spondingly, the CCK-induced [Ca2+]c dynamics in acini isolated from 9-mo-old rats was impaired compared to that of young rats but normal in aged, chronically alcohol-fed rats. Aml secretion under CCK stimulation, however, which was decreased in aged rats, was additionally impaired after alcohol feeding.  相似文献   
50.
Respiratory chain deficiencies have long been regarded as rare neuromuscular diseases mostly originating from mutations in the mitochondrial genome. Research in the last years has created quite a different picture. The clinical spectrum has expanded to multiorgan disease manifestation, with an estimated minimum incidence in children of 1:11,000. Mutations in the nuclear genome have been discovered in recent years, thereby adding mendelian genetics to the broadened spectrum of mitochondrial disease. This review summarizes recent advances in mitochondrial disorders with a special focus on childhood presentation and therapeutic approaches that may prove useful in the future.  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