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   708787篇
  免费   50117篇
  国内免费   1319篇
耳鼻咽喉   9189篇
儿科学   23557篇
妇产科学   17651篇
基础医学   110878篇
口腔科学   20090篇
临床医学   64007篇
内科学   134908篇
皮肤病学   16383篇
神经病学   49653篇
特种医学   25817篇
外国民族医学   76篇
外科学   105149篇
综合类   14892篇
现状与发展   2篇
一般理论   162篇
预防医学   51511篇
眼科学   16538篇
药学   54435篇
  4篇
中国医学   2376篇
肿瘤学   42945篇
  2021年   5591篇
  2018年   7960篇
  2017年   6174篇
  2016年   6936篇
  2015年   7697篇
  2014年   10443篇
  2013年   15625篇
  2012年   20849篇
  2011年   21863篇
  2010年   12919篇
  2009年   12087篇
  2008年   20289篇
  2007年   21789篇
  2006年   22152篇
  2005年   20705篇
  2004年   20265篇
  2003年   19167篇
  2002年   18629篇
  2001年   36377篇
  2000年   36935篇
  1999年   30422篇
  1998年   7935篇
  1997年   6691篇
  1996年   6992篇
  1995年   6652篇
  1994年   6116篇
  1993年   5610篇
  1992年   22994篇
  1991年   22948篇
  1990年   22334篇
  1989年   22099篇
  1988年   20042篇
  1987年   19432篇
  1986年   18478篇
  1985年   17316篇
  1984年   12710篇
  1983年   10746篇
  1982年   5937篇
  1979年   11529篇
  1978年   8146篇
  1977年   6843篇
  1976年   6602篇
  1975年   7273篇
  1974年   8503篇
  1973年   8142篇
  1972年   7660篇
  1971年   7128篇
  1970年   6878篇
  1969年   6306篇
  1968年   5782篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
In the United States, renal cell carcinoma (RCC) incidence and the prevalence of obesity, an established risk factor for RCC, have been increasing for several decades. RCC is more common among older individuals. We sought to quantify the contribution of excess adiposity to the rising incidence of RCC among individuals 60 years or older. National Institutes of Health-American Association of Retired Persons Diet and Health Study data (n = 453 859 participants, enrolled in 1995-1996, age at enrollment 50-71 years) were used to estimate multivariable-adjusted hazard ratios (HRs) for RCC across body mass index categories and HRs associated with smoking. Population attributable fractions (PAFs) were calculated using estimated HRs and annual overweight/obesity prevalence from the National Health Interview Survey (1985-2008). PAF estimates were combined with RCC incidence from Surveillance, Epidemiology and End Results-13 to calculate annual percent changes in RCC incidence attributable (and unrelated) to overweight/obesity. We found that between 1995 and 2018, among individuals aged 60 years and older, PAF for overweight/obesity increased from 18% to 29% for all RCCs. In comparison, the PAF for smoking declined from 12% to 9%. RCC incidence increased 1.8% per year (95% confidence interval [CI] 1.5%-2.1%) overall, while RCC incidence attributable to overweight/obesity increased 3.8% per year (95%CI 3.5%-4.2%) and RCC incidence unrelated to overweight/obesity increased 1.2% per year (95% CI 0.9%-1.4%). In conclusion, overweight/obesity appears to have contributed importantly to the rising incidence of RCC in the United States since the mid-1990s. Public health interventions focused on reducing overweight and obesity could help substantially in curbing this trend.  相似文献   
56.
57.
58.

Objective

Successful weight loss interventions for African-Americans adolescents are lacking. Cognitive-behavioral interventions seek to develop weight loss skills (e.g., counting calories, goal setting, managing one's environment). Little is known about how well adolescents implement such skills in their daily lives. Study aims were to (1) examine weight loss skills utilization at midpoint and end of a 6-month cognitive-behavioral/motivational interviewing weight loss sequential multiple assignment randomized trial (SMART), and (2) determine if greater skill utilization predicted weight loss at treatment end and 3 months post-treatment.

Method

One hundred and eighty six African-Americans adolescents with obesity and their caregiver were first randomly assigned to complete 3 months of cognitive-behavioral and motivational interviewing family-based weight loss treatment in their home or in the research office (Phase 1). Nonresponders (i.e., those who lost < 3% of initial weight, n?=?161) were rerandomized to 3 months of continued skills training (n?=?83) or contingency management (n?=?78) for Phase 2; responders were allocated to 3 months of relapse prevention (n?=?20). Adolescents’ frequency of weight loss skills utilization was assessed via questionnaire at treatment midpoint and end.

Results

Higher treatment attendance was associated with better skill utilization. Higher skill utilization was associated with more weight loss at treatment end, whereas higher baseline confidence was associated with more weight loss at follow-up.

Conclusions

This study indicates the importance of attending weight loss intervention sessions to develop and strengthen weight loss skills in African-American adolescents with obesity, and strengthening confidence to use such skills for continued weight loss.  相似文献   
59.
Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future.  相似文献   
60.
Neuroscience and Behavioral Physiology - Objective. To determine the frequency, structure, and severity of cognitive impairments in patients with bipolar affective disorder (BAD) in remission....  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