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   1039篇
  免费   52篇
  国内免费   36篇
耳鼻咽喉   4篇
儿科学   55篇
妇产科学   18篇
基础医学   101篇
口腔科学   19篇
临床医学   113篇
内科学   202篇
皮肤病学   8篇
神经病学   38篇
特种医学   201篇
外科学   66篇
综合类   14篇
一般理论   1篇
预防医学   32篇
眼科学   16篇
药学   90篇
中国医学   5篇
肿瘤学   144篇
  2021年   7篇
  2020年   6篇
  2019年   7篇
  2018年   13篇
  2017年   8篇
  2016年   4篇
  2015年   7篇
  2014年   17篇
  2013年   19篇
  2012年   17篇
  2011年   24篇
  2010年   45篇
  2009年   45篇
  2008年   31篇
  2007年   43篇
  2006年   19篇
  2005年   26篇
  2004年   14篇
  2003年   8篇
  2002年   27篇
  2001年   19篇
  2000年   22篇
  1999年   23篇
  1998年   55篇
  1997年   56篇
  1996年   55篇
  1995年   49篇
  1994年   47篇
  1993年   31篇
  1992年   19篇
  1991年   20篇
  1990年   22篇
  1989年   45篇
  1988年   34篇
  1987年   24篇
  1986年   25篇
  1985年   18篇
  1984年   14篇
  1983年   7篇
  1982年   14篇
  1981年   14篇
  1980年   18篇
  1979年   18篇
  1978年   11篇
  1977年   17篇
  1976年   10篇
  1975年   12篇
  1974年   6篇
  1973年   6篇
  1972年   9篇
排序方式: 共有1127条查询结果,搜索用时 15 毫秒
101.
102.
Increased patients' serum anticholinergic activity (SAA) is described as a marker of cognitive dysfunction and can be influenced by different exogenous and endogenous factors. The role of cortisol in relation to SAA and cognition in perioperative conditions has not been investigated so far. In 30 men scheduled for urological surgery, the authors determined SAA and cortisol levels in blood and CSF and conducted neuropsychological testing in two subgroups with comparable pre- and intraoperative characteristics, one group with low SAA (mean=2.4 [SD=0.9], n=23) and the other with high SAA (mean=5.1 [SD=2.4], n=7) values. Increased SAA was associated with two times the number of anticholinergic medications but not with patients' age, medical history or impaired cognition. A significant linear correlation was detected between anticholinergic activities and cortisol levels. Thus, endogenous factors such as patients' stress levels should be taken into account for interpretation of the role of SAA.  相似文献   
103.
The C‐variant of a T‐13910C polymorphism (rs4988235; NT_022135.15:g.25316568G > A) upstream of the lactase phlorizin hydrolase (LPH) gene causes lactose intolerance. Association studies with differences in bone parameters and fracture risk have been inconclusive. The objective of this study was to examine the association of LPH rs4988235 with body height and bone parameters and calcium homeostasis in two elderly populations of Dutch Caucasians and assess interaction with vitamin D receptor (VDR) polymorphisms. Genotyping of LPH and VDR polymorphisms was performed in 6367 individuals from the Rotterdam Study and 844 from the Longitudinal Aging Study Amsterdam (LASA). Associations with age, height, weight, bone mineral density (BMD), skeletal morphometric parameters and serum vitamin D and calcium levels, and dietary calcium intake were assessed using ANOVA or analysis of covariance, and allele dose effect was assessed using linear regression analysis. Fracture risk was analyzed using Cox's proportional hazard regression analysis. Associations with body height (p = 2.7 × 10?8) and vertebral area (p = .048) found in the Rotterdam Study were explained by population stratification, as assessed by principal‐component analyses, and disappeared after additional adjustments. No associations with femoral neck or lumbar spine BMD or with fracture risk were detected. Calcium intake and serum ionized serum calcium were significantly lower in C‐homozygotes (p = 9.2 × 10?7, p = .02, respectively). For none of the parameters studied was interaction between the T‐13910C polymorphism and VDR block 5 haplotype 1 observed. We show that the C allele of the T‐13910C polymorphism causing lactose intolerance is associated with lower dietary calcium intake and serum calcium levels but not with BMD or fractures. The associations observed with height and vertebral area were the result of population stratification. This demonstrates the impact of population stratification and urges researchers to carefully take this into account in genetic associations, in particular, in dietary intake–related phenotypes, of which LPH and lactose intolerance are a strong example. © 2010 American Society for Bone and Mineral Research  相似文献   
104.

Objectives

The aim of the study was to describe growth and body composition changes in HIV‐positive children after they had initiated or changed antiretroviral therapy (ART) and to correlate these with viral, immune and treatment parameters.

Methods

Ninety‐seven prepubertal HIV‐positive children were observed over 48 weeks upon beginning or changing ART. Anthropometry and bioelectrical impedance analysis results were compared with results from the National Health and Nutrition Examination Survey 1999–2002 (NHANES) to generate z‐scores and with results for HIV‐exposed, uninfected children from the Women and Infants Transmission Study (WITS). Multivariate analysis was used to evaluate associations between growth and body composition and disease parameters.

Results

All baseline lean and fat mass measures were below those of controls from NHANES. Weight, height and fat free mass (FFM) index (FFM/height2) z‐scores increased over time (P=0.004, 0.037 and 0.027, respectively) and the waist:height ratio z‐score decreased (P=0.045), but body mass index and per cent body fat z‐scores did not change. Measures did not increase more than in uninfected WITS controls. In multivariate analysis, baseline height, mid‐thigh circumference and FFM z‐scores related to CD4 percentage (P=0.029, P=0.008 and 0.020, respectively) and change in FFM and FFM index z‐scores to CD4 percentage increase (P=0.010 and 0.011, respectively). Compared with WITS controls, baseline differences in height and mid‐thigh muscle circumference were also associated with CD4 percentage. Case–control differences in change in both subscapular skinfold (SSF) thickness and the SSF:triceps skinfold ratio were inversely associated with viral suppression. No measures related to ART class(es) at baseline or over time.

Conclusions

In these HIV‐positive children, beginning or changing ART was associated with improved growth and lean body mass (LBM), as indicated by FFM index. Height and LBM related to CD4 percentage at baseline and over time. Altered fat distribution and greater central adiposity were associated with detectable virus but not ART class(es) received.  相似文献   
105.
106.
107.
Mattern M 《Der Nervenarzt》2007,78(9):1062; author reply 1062-1062; author reply 1064
  相似文献   
108.

Background  

Mental health problems have become more common among young people over the last twenty years, especially in certain countries. The reasons for this have remained unclear. The hypothesis tested in this study is that national trends in young people's mental health are associated with national trends in young people's labour market.  相似文献   
109.
Glucocorticoids have been widely used as cotreatment for patients with cancer due to potent pro-apoptotic properties in lymphoid cells, reduction of nausea and diminishing acute toxicity on normal tissue. There are now data from preclinical and, to some extent, clinical studies, demonstrating that these medicaments are highly suspicious to induce therapy resistance in the majority of malignant solid tumors-irrespective of tumor origin and the nature of specific anticancer drugs or irradiation used for treatment. Despite these huge amounts of data, the underlying mechanisms of cell type-specific signaling by these steroid hormones are just beginning to be described. This review summarizes our present understanding of a relationship between glucocorticoid-induced reversible cell cycle arrest and therapy resistance in solid tumors. We give a summary of our current knowledge of decreased proliferation rates in response to glucocorticoid pre and combination treatment which are suspicious to be involved not only in protection of normal tissues, but also in protection of solid tumors from cytotoxic effects of anticancer agents. The inhibition of cell cycle progression by pretreatment with GCs may be crucially involved in switching the balance of several interacting pathways to survival upon treatment with GCs.  相似文献   
110.
High-throughput screening for inhibitors of the human metalloprotease, methionine aminopeptidase-2 (MetAP2), identified a potent class of 3-anilino-5-benzylthio-1,2,4-triazole compounds. Efficient array and interative synthesis of triazoles led to rapid SAR development around the aniline, benzylthio, and triazole moeities. Evaluation of these analogs in a human MetAP2 enzyme assay led to the identification of several inhibitors with potencies in the 50-100 picomolar range. The deleterious effects on inhibitor potency by methylation of the anilino-triazole nitrogens, as well as the X-ray crystal structure of triazole 102 bound in the active site of MetAP2, confirm the key interactions between the triazole nitrogens, the active site cobalt atoms, and the His-231 side-chain. The structure has also provided a rationale for interpreting SAR within the triazole series. Key aniline (2-isopropylphenyl) and sulfur substituents (furanylmethyl) identified in the SAR studies led to the identification of potent inhibitors (103 and 104) of endothelial cell proliferation. Triazoles 103 and 104 also exhibited dose-dependent activity in an aortic ring tissue model of angiogenesis highlighting the potential utility of MetAP2 inhibitors as anticancer agents.  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