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   2674篇
  免费   385篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   102篇
妇产科学   39篇
基础医学   85篇
口腔科学   69篇
临床医学   114篇
内科学   322篇
皮肤病学   14篇
神经病学   41篇
特种医学   146篇
外科学   125篇
综合类   13篇
预防医学   1875篇
眼科学   8篇
药学   18篇
肿瘤学   89篇
  2023年   31篇
  2022年   51篇
  2021年   26篇
  2020年   88篇
  2019年   26篇
  2018年   94篇
  2017年   99篇
  2016年   99篇
  2015年   91篇
  2014年   92篇
  2013年   159篇
  2012年   36篇
  2011年   35篇
  2010年   112篇
  2009年   129篇
  2008年   61篇
  2007年   60篇
  2006年   77篇
  2005年   51篇
  2004年   46篇
  2003年   25篇
  2002年   83篇
  2001年   93篇
  2000年   57篇
  1999年   135篇
  1998年   157篇
  1997年   195篇
  1996年   206篇
  1995年   129篇
  1994年   56篇
  1993年   121篇
  1992年   19篇
  1991年   10篇
  1990年   17篇
  1989年   30篇
  1988年   33篇
  1987年   25篇
  1986年   30篇
  1985年   23篇
  1984年   11篇
  1983年   16篇
  1982年   16篇
  1981年   15篇
  1980年   12篇
  1979年   9篇
  1978年   8篇
  1977年   9篇
  1976年   17篇
  1975年   7篇
  1974年   5篇
排序方式: 共有3063条查询结果,搜索用时 31 毫秒
991.
The Healthy Eating Asians Remain Together (HEART) study was carried out to investigate the relationship between 24‐hour urine nutritional biomarkers and cardiometabolic risks in India. A total of 168 participants underwent health examination to assess body mass index, blood pressure, and 24‐hour urine samples. The participants were divided into normotensive and hypertensive. The average blood pressure, weight, and body mass index were significantly high in patients considered to be hypertensive, and 24‐hour urine biomarkers showed significant differences in sodium and magnesium/creatinine ratios in patients aged 40 and older. High sodium intake and reduction in magnesium consumption are associated with increased blood pressure in patients from India.  相似文献   
992.
Polymorphic variability in the enzymes involved in biotransformation of tobacco‐related pro‐carcinogens plays an important role in modulating oral cancer susceptibility. CYP1A1*2A, CYP1A1*2C, GSTM1 and GSTT1 polymorphisms were determined in 122 oral carcinoma cases and 127 controls from Gujarat, West India using PCR‐based methods. The results revealed that the polymorphic variants of CYP1A1 gene did not show association towards oral cancer risk. The GSTM1 and GSTT1 null genotypes were found to be over‐represented in patients than controls, suggesting a moderate increase in risk of oral cancer. The oral cancer risk was significantly increased in the patients having either alone or concurrent deletion of GSTM1 and GSTT1. The results also suggested significant association between tobacco habits, especially chewing, variant genotypes of CYP1A1, GSTM1 and GSTT1 and oral cancer risk. Our data have provided evidence that GST polymorphism modified the susceptibility to oral cancer and individuals with variant genotypes of the three genes with tobacco habits are at significant risk of developing oral cancer.  相似文献   
993.
994.
995.
996.
997.
Objective To describe the process and results of diet standardization, diet validation, and monitoring of diet composition, which were key components of protocol 1 of Dietary Effects on Lipoproteins and Thrombogenic Activity (DELTA-1), the initial protocol in a program of multicenter human feeding studies designed to evaluate the effects of amount and type of fat on lipoproteins and hemostasis parameters in various demographic groups.Design DELTA-1 was based on a randomized, blinded, crossover experimental design. Three diets were fed for 8 weeks to 103 healthy men and women aged 22 to 67 years at 4 field centers. Diet A, an average American diet, was designed to provide 37% of energy from fat, 16% of energy from saturated fatty acids (SFAs); diet B (step 1 diet) was designed to provide 30% of energy from fat, 9% of energy from SFA; and diet C (low SFA diet) was designed to provide 26% of energy from fat, 5% of energy from SFA. Key features of diet standardization included central procurement of fat-containing foods, inclusion of standard ingredients, precision weighing of foods—especially sources of fat and cholesterol—and use of standardized written procedures.Setting For menu validation, a set of 12 menus for each diet was prepared in duplicate and chemically assayed. For monitoring of diet composition during the study, an 8-day diet cycle (6 weekday and 2 weekend menus) was sampled by every field center twice during each of 3 feeding periods.Statistical analyses Means (±standard error) were calculated and compared with target nutrient specifications.Results DELTA-1 was able to provide a standardized diet that met nutrient specifications across 4 field centers over 24 weeks of participant feeding spanning a total of 8 months.Applications Prestudy chemical validation of menus and continuous sampling and assay of diets throughout the study are essential to standardize experimental diets and to ensure that nutrient target goals are met and maintained throughout a controlled multicenter feeding study. J Am Diet Assoc. 1998;98:766–776.  相似文献   
998.
999.
1000.
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