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   104892篇
  免费   29952篇
  国内免费   1080篇
耳鼻咽喉   2488篇
儿科学   2871篇
妇产科学   2440篇
基础医学   3501篇
口腔科学   5134篇
临床医学   26995篇
内科学   25661篇
皮肤病学   3362篇
神经病学   13154篇
特种医学   3840篇
外国民族医学   1篇
外科学   18565篇
综合类   289篇
现状与发展   40篇
一般理论   18篇
预防医学   14522篇
眼科学   2333篇
药学   1446篇
中国医学   20篇
肿瘤学   9244篇
  2024年   750篇
  2023年   5077篇
  2022年   1172篇
  2021年   2893篇
  2020年   5428篇
  2019年   2196篇
  2018年   7041篇
  2017年   7457篇
  2016年   8017篇
  2015年   8106篇
  2014年   10570篇
  2013年   12292篇
  2012年   4140篇
  2011年   3844篇
  2010年   6954篇
  2009年   9218篇
  2008年   3753篇
  2007年   2697篇
  2006年   3828篇
  2005年   2403篇
  2004年   1808篇
  2003年   1499篇
  2002年   1313篇
  2001年   2021篇
  2000年   1352篇
  1999年   1857篇
  1998年   2159篇
  1997年   1979篇
  1996年   2003篇
  1995年   1802篇
  1994年   1233篇
  1993年   1035篇
  1992年   937篇
  1991年   794篇
  1990年   644篇
  1989年   676篇
  1988年   644篇
  1987年   487篇
  1986年   463篇
  1985年   405篇
  1984年   341篇
  1983年   384篇
  1982年   286篇
  1981年   228篇
  1980年   163篇
  1979年   141篇
  1978年   171篇
  1977年   168篇
  1974年   124篇
  1972年   128篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Background: Vitamin B12 deficiency after gastric surgery for obesity is due to a failure of separation of vitamin B12 from protein foodstuffs and to a failure of absorption of crystalline vitamin B12 in the presence of intrinsic factor. The purpose of this study was to determine which of four oral doses of crystalline vitamin B12 was most effective in treating vitamin B12 deficiency in 102 patients. Methods and Results: At time of entry into the study, the patients had a serum vitamin B12 < 100 pmol L −1, were 29.9 ± 21.7 months post-op, were 37 ± 8 years old and had a body mass index of 30 ± 6 kg m−2. Eight (8%) had had a vertical banded gastroplasty and 94 (92%) a gastric bypass. For the first 3 months all patients received 350 μg per day of crystalline vitamin B12 and all increased their serum vitamin B12 levels to over 100 pmol L−1. The patients were then assigned to receive for a further 3 month period one of four oral doses of crystalline vitamin B12-100 μg, 250 μg, 350 μg and 600 μg. Serum vitamin B12 levels were greater than 150 pmol L−1 after 6 months in 83.3% of patients who received 100 μg; 92.3% of patients who received 250 μg; 94.7% after 350 μg and 95.2% after 600 μg (p%0.525). Conclusion: At least 350 μg per day is the appropriate oral dose of crystalline vitamin B12 after gastric surgery for obesity to correct low serum vitamin B12 levels in 95% of patients.  相似文献   
992.
Nutrient Intake following Vertical Banded Gastroplasty or Gastric Bypass   总被引:3,自引:3,他引:0  
Background: This study explored eating habits, nutrient intake, and blood vitamin and mineral levels to determine whether severely obese subjects (BMI 40-50 kg m−2) post-vertical banded gastroplasty (VBG) or gastric bypass Roux-en-Y (GBR) are at risk of developing compounded under-nutrition. Methods: A dietary follow-up of 36 VBG and 19 GBR was maintained for 18 months via 7-day food intake diaries and 24-h recalls. Food intake was analysed for energy and nutrient composition and for its relative amount to recommended dietary allowances (RDA). Results: Weight loss was greatest during the first 6 months, continued at a slower rate for the next 6 months, nearly ceasing thereafter. The results following GBR were not substantially different from those following VBG 18 months postoperatively. The median weight loss at 1 year postoperatively was 48, 46, 48 and 36 kg; expressed as residual excess body weight: 0.2, 16, 13 and 22% for GBR Men, Women, VBG Men, Women, respectively. According to the classification proposed by Reinhold, all subjects achieved excellent treatment outcomes 18 months postoperatively. Despite the relatively low reported energy intake (20-50% below RDA), no correlation was found between rate of weight loss and energy intake at 6 months postoperatively. The intake of most vitamins and minerals was below 50% of RDA during the 18 months follow-up. The increase in energy intake did not improve the level of the nonenergy-contributing nutrients. Compliance to multivitamin and mineral supplement intake deteriorated with time. Conclusion: The low to within-normal range of blood vitamin and mineral levels 12 months postoperatively suggests the slow development of subclinical nutritional deficiency which could jeopardize the subjects' long-term health status.  相似文献   
993.
This study was undertaken to determine the effects of a partner-support, incentive-baed educational program on breast feeding knowledge, attitudes and support and to examine the relationship between feeding intentions and feeding behavior among low-income women. Women who expressed a willingness to participate in the intervention were randomly assigned to intervention and usual breast feeding (control) groups. Sixty-eight primipara women, with expected due dates between May and December, 1992, volunteered to participate in the study. Of these, 34 were randomly assigned to each of the two groups. Approximately 81 percent of the women completed the study, leaving n=29 in the control group and n-26 in the intervention group. The intervention consisted of special incentives (prizes) for women and their partners to participate in several breast feeding education and promotion activities. Intervention group women and their partners experienced positive changes in breast feeding knowledge and attitudes. Furthermore, the intervention seemed to have influenced more women in the treatment group to breast feed despite their prenatal feeding intentions. In addition, the partners of intervention group women were perceived to be more supportive of, breast feeding than control group partners. These findings suggest that incentives, such as donated prizes, can be used to attract lower socioeconomic group women and their partners to breast feeding promotion interventions. Participation in such interventions can produce positive changes in breast feeding knowledge, attitudes, and support, and can have a dramatic effect in promoting breast feeding.This study was supported through contract no. 59-3198-1-050 from the Food and Nutrition Service, U.S. Department of Agriculture.  相似文献   
994.
Moore JD  Burns J 《Modern healthcare》1995,25(22):26-8, 30, 32
Frustrated by layoffs and new rules, healthcare workers are striking back. Nurses, such as those rallying in Seattle, are leading the charge. Interest in unions is rising. Specifically, unions have made inroads in efforts to organize nursing home workers, p. 28.  相似文献   
995.
996.
997.
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