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   133757篇
  免费   8272篇
  国内免费   1244篇
耳鼻咽喉   2059篇
儿科学   2133篇
妇产科学   2051篇
基础医学   21368篇
口腔科学   3190篇
临床医学   12448篇
内科学   24163篇
皮肤病学   4291篇
神经病学   10896篇
特种医学   7559篇
外科学   17721篇
综合类   604篇
现状与发展   3篇
一般理论   28篇
预防医学   6980篇
眼科学   3426篇
药学   12016篇
中国医学   1519篇
肿瘤学   10818篇
  2023年   698篇
  2022年   2206篇
  2021年   4651篇
  2020年   2270篇
  2019年   3143篇
  2018年   3916篇
  2017年   3201篇
  2016年   4181篇
  2015年   5796篇
  2014年   6885篇
  2013年   8031篇
  2012年   11942篇
  2011年   11435篇
  2010年   6594篇
  2009年   5692篇
  2008年   8046篇
  2007年   7602篇
  2006年   6884篇
  2005年   6358篇
  2004年   5554篇
  2003年   4846篇
  2002年   4189篇
  2001年   3200篇
  2000年   2960篇
  1999年   2271篇
  1998年   964篇
  1997年   729篇
  1996年   548篇
  1995年   481篇
  1994年   407篇
  1993年   355篇
  1992年   783篇
  1991年   749篇
  1990年   669篇
  1989年   596篇
  1988年   512篇
  1987年   499篇
  1986年   355篇
  1985年   388篇
  1984年   276篇
  1983年   214篇
  1982年   142篇
  1981年   176篇
  1980年   144篇
  1979年   247篇
  1978年   185篇
  1977年   143篇
  1976年   144篇
  1974年   150篇
  1973年   130篇
排序方式: 共有10000条查询结果,搜索用时 157 毫秒
71.
72.
73.
74.
75.
76.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  相似文献   
77.
Objective: This study investigated the effect of regular swimming exercise according to the duration-intensity on neurocognitive function in a cerebral infarction rat model.

Methods: Forty male Sprague–Dawley 10-week-old rats, weighing 300 ± 50 g, were subjected to photothrombotic cerebral infarction. The remaining 36 rats were randomly divided into four groups (n = 9 per group: non-exercise (group A); swimming exercise of short duration-intensity (5 min/day, group B); swimming exercise of moderate duration-intensity (10 min/day, group C); and swimming exercise of long duration-intensity (20 min/day, group D). Exercise was performed five times a week for 4 weeks, beginning the day after cerebral infarction. Neurocognitive function was evaluated with the Morris water maze test. Immunohistochemistry and western blot analysis examined brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) at 4 weeks postinfarction.

Results: At 4 weeks postinfarction, escape latency was found to be shorter in group C than in any of groups A, B, or D. Immunohistochemistry revealed the most significant immunoreactivity for BDNF and VEGF in group C. Western blot analysis demonstrated that BDNF and VEGF proteins were markedly expressed in group C.

Conclusions: Regular swimming exercise of moderate duration-intensity may be the most effective exercise protocol for the recovery of neurocognitive function in cerebral infarction rat model.  相似文献   

78.
Young children enter kindergarten with varying levels of readiness and abilities to learn. One factor that contributes to lower levels of school readiness is poverty. One timely, cost-effective, and feasible strategy to boost school readiness, regardless of exposure to high-quality preschool is to leverage the summer months prior to kindergarten entry and provide comprehensive, evidence-based programming immediately before the school year begins. The current study implemented a community-based summer programme targeted at improving school readiness for 25 four- and five-year-old children in a low-income community. Across the 9-week study, children participated in two types of early literacy activities and the Incredible Years social/emotional learning curriculum. Results indicate that participants demonstrated significant growth across three early literacy skills and were rated as overall stable regarding their behaviour across the summer. These results are discussed along with implications and future directions in this line of research.  相似文献   
79.
80.
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