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   1231篇
  免费   77篇
  国内免费   63篇
耳鼻咽喉   2篇
儿科学   85篇
妇产科学   4篇
基础医学   124篇
口腔科学   26篇
临床医学   157篇
内科学   314篇
皮肤病学   24篇
神经病学   28篇
特种医学   267篇
外科学   63篇
综合类   61篇
预防医学   86篇
眼科学   8篇
药学   99篇
肿瘤学   23篇
  2022年   3篇
  2021年   15篇
  2020年   3篇
  2019年   6篇
  2018年   7篇
  2017年   9篇
  2016年   12篇
  2015年   13篇
  2014年   24篇
  2013年   29篇
  2012年   36篇
  2011年   33篇
  2010年   31篇
  2009年   47篇
  2008年   48篇
  2007年   65篇
  2006年   44篇
  2005年   42篇
  2004年   22篇
  2003年   21篇
  2002年   26篇
  2001年   32篇
  2000年   29篇
  1999年   41篇
  1998年   61篇
  1997年   67篇
  1996年   64篇
  1995年   59篇
  1994年   43篇
  1993年   42篇
  1992年   20篇
  1991年   28篇
  1990年   23篇
  1989年   50篇
  1988年   41篇
  1987年   38篇
  1986年   23篇
  1985年   24篇
  1984年   16篇
  1983年   7篇
  1982年   17篇
  1981年   19篇
  1980年   20篇
  1979年   16篇
  1978年   7篇
  1977年   17篇
  1976年   11篇
  1975年   9篇
  1972年   3篇
  1969年   3篇
排序方式: 共有1371条查询结果,搜索用时 15 毫秒
81.
Most of the counselling in health care targeted at child nutrition is delivered via the parents, but little is known about the effects of such counselling on the nutrition knowledge and dietary habits of the parents. In the Special Turku Coronary Risk Factor Intervention Project for Children (STRIP), we studied how 6.5 years of child-targeted nutrition counselling affected the knowledge, attitudes and dietary habits of the parent mainly responsible for food purchase and preparation. We used a questionnaire and a 24-h recall interview in a time-restricted cohort of 98 families belonging to the intervention group and 89 families belonging to the control group in the STRIP project. After controlling for background variables, the intervention parents had better knowledge than the control parents of causal relationships between food choices and coronary heart disease and of the nutritional composition of foods. Knowledge of nutrition concepts did not differ between the two groups. The quality of fat was better in the diet of the intervention parents, they consumed less salt and they also had more knowledge concerning these subjects compared to the control parents (higher behavioural capability scores). The behavioural capability scores of the total group correlated poorly with their nutrient intakes. Thus, child-targeted nutrition intervention delivered to the parents increased parental nutrition knowledge and improved the quality of the parents' diet. However, as nutrition knowledge of the parents correlated poorly with their nutrient intakes, other factors than knowledge appear to influence parental dietary decisions.  相似文献   
82.

Objective

To more accurately define the annual incidence of cholera in India, believed to be higher than reported to the World Health Organization (WHO).

Methods

We searched the biomedical literature to extract data on the cases of cholera reported in India from 1997 to 2006 and compared the numbers found to those reported annually to WHO over the same period. The latter were obtained from WHO’s annual summaries of reported cholera cases and National health profile 2006, published by India’s Central Bureau of Health Intelligence.

Findings

Of India’s 35 states or union territories, 21 reported cholera cases during at least one year between 1997 and 2006. The state of West Bengal reported cases during all 10 years, while the state of Maharashtra and the union territory of Delhi reported cases during nine, and Orissa during seven. There were 68 outbreaks in 18 states, and 222 038 cases were detected overall. This figure is about six times higher than the number reported to WHO (37 783) over the same period. The states of Orissa, West Bengal, Andaman and Nicobar Islands, Assam and Chhattisgarh accounted for 91% of all outbreak-related cases.

Conclusion

The reporting of cholera cases in India is incomplete and the methods used to keep statistics on cholera incidence are inadequate. Although the data are sparse and heterogeneous, cholera notification in India is highly deficient.  相似文献   
83.
为摸清我省儿童1型糖尿病的发病情况,按WHO儿童糖尿病多国研究计划方案,我们在自贡市(四区,两县)对1989~1996年儿童1型糖尿病发病率进行了调查研究。1 材料与方法1.1 病例来源 第一来源:自贡市30个县区级有1型糖尿病诊断能力的医院。第二来...  相似文献   
84.
目的和方法目前尚不清楚,摄入非水溶性钙盐的钙吸收是否比摄入水溶性差的钙盐钙吸收更好;另外也不清楚,牛奶制品的钙吸收是否比钙盐钙吸收更好。作者采用一种单次服用就能精确测定钙的净吸收率的方法,给8例健康空腹受试者服用含500mg钙的5种不同水溶性的钙盐和牛奶,服用顺序是随机的。结果按钙盐的水溶性递减次序排列,以平均钙的净吸收率±标准误表示:醋酸钙(32±4)%,乳酸钙(32±4)%,葡萄糖酸钙(27±3)%,柠檬酸钙(30±3)%;碳酸钙(39±3)%。按方差分析,钙盐和牛奶的钙吸收率差异无统计学意义…  相似文献   
85.
Associations among serum lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides) and levels of serum zinc (S-Zn), serum copper (S-Cu), and their ratio were analyzed in 3373 3-, 6-, 9-, 12-, 15-, and 18-year-old Finnish girls and boys. S-Zn was positively related to total cholesterol, HDL-cholesterol, and LDL-cholesterol; S-Cu related negatively to HDL-cholesterol. Obesity did not affect these relationships. The few exceptionally high lipid levels found were not associated with very low or high S-Zn or S-Cu. S-Zn and S-Cu were related to serum lipids; causality between the variables, however, remains to be studied.  相似文献   
86.
OBJECTIVES: To study the effect of vitamin D supplementation and the impact of summer season on serum 25-hydroxyvitamin D (S-25(OH)D) in Finnish 9-15-y-old girls. DESIGN: Three-year follow-up study with vitamin D(2) supplementation using D(2) 10 microg daily from October to January for the first and from October to February for the second winter as well as 20 microg daily from October to March for the third winter. SETTING: Paavo Nurmi Centre, University of Turku, Turku, Finland. SUBJECTS: A total of 171 female volunteers aged 9-15 y. METHODS: Vitamin D and calcium intakes were estimated by a semi-quantitative food frequency questionnaire (FFQ). S-25(OH)D was measured by radioimmunoassay. RESULTS: The median daily dietary intakes of vitamin D and calcium were 3.8 microg (interquartile range (IQR) 2.7-5.0) and 1451 mg (IQR 1196-1812), respectively, over 3 y. The prevalence of severe hypovitaminosis D (S-25(OH)D<20 nmol/l) was 14% and of moderate hypovitaminosis D (20 nmol/l < or = S-25(OH)D < or = 37.5 nmol/l) 75% at baseline in winter. None of the participants had severe hypovitaminosis D in summer. The effect of 10 microg of D(2) daily was insufficient to raise S-25(OH)D from baseline. The daily supplementation of 20 microg of D(2) increased S-25(OH)D significantly in wintertime compared with the non-supplement users (to 45.5 vs 31.8 nmol/l; P<0.001). None of the subjects with vitamin D(2) supplementation approximately 20 microg daily had severe hypovitaminosis D; however, 38% of those participants had moderate hypovitaminosis D at 36 months. Sun exposure in summer raised mean S-25(OH)D to 62.0 nmol/l. Both the daily supplementation of approximately 20 microg of D(2) and summer sunlight exposure had more effect on those who had severe hypovitaminosis than those who had a normal vitamin D status (increase of 24.2 vs 0.9 nmol/l (P<0.001), and 38.8 vs 18.2 nmol/l (P<0.001), respectively). CONCLUSION: Vitamin D supplementation daily with 20 microg is needed to prevent hypovitaminosis D in peripubertal Finnish girls in winter. Sunlight exposure in summer is more effective than approximately 20 microg of D(2) supplementation daily in winter to raise S-25(OH)D. Both the daily supplementation with 20 microg of D(2) and summertime sunlight exposure had more effect on those who had severe hypovitaminosis D than those who had a normal vitamin D status. SPONSORSHIP: Supported by the Yrj? Jahnsson Foundation and the Medical Research Foundation of the Turku University Central Hospital.  相似文献   
87.
88.
89.
90.
Original Gianturco expandable stents and their modifications were used to create an experimental intrahepatic portacaval anastomosis (EIPCA) in 30 young domestic swine without portal hypertension. The study focused on the design of a suitable stent, the technique of its application, and the evaluation of short-term patency of the EIPCA. A stent with a 2.5-cm-long body and wire skirts on both ends was most suitable for EIPCA creation. Well-positioned stents shunted most of the portal blood in the inferior vena cava circulation and remained patent for 4-6 weeks. Ingrowth of liver parenchyma and abundant proliferation of the intima and connective tissue inside the stent lumen in these rapidly growing animals gradually decreased EIPCA patency, and thrombus formation with diminished blood flow closed them completely.  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