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   30609篇
  免费   2242篇
  国内免费   2427篇
耳鼻咽喉   90篇
儿科学   325篇
妇产科学   1240篇
基础医学   1770篇
口腔科学   619篇
临床医学   2683篇
内科学   7870篇
皮肤病学   1438篇
神经病学   4064篇
特种医学   878篇
外科学   7040篇
综合类   293篇
预防医学   4823篇
眼科学   161篇
药学   841篇
中国医学   9篇
肿瘤学   1134篇
  2018年   279篇
  2017年   424篇
  2016年   1058篇
  2015年   1037篇
  2014年   1288篇
  2013年   2178篇
  2012年   487篇
  2011年   630篇
  2010年   1034篇
  2009年   1487篇
  2008年   598篇
  2007年   573篇
  2006年   1099篇
  2005年   922篇
  2004年   737篇
  2003年   845篇
  2002年   830篇
  2001年   956篇
  2000年   721篇
  1999年   828篇
  1998年   827篇
  1997年   816篇
  1996年   1002篇
  1995年   1147篇
  1994年   963篇
  1993年   843篇
  1992年   882篇
  1991年   777篇
  1990年   642篇
  1989年   619篇
  1988年   588篇
  1987年   629篇
  1986年   507篇
  1985年   614篇
  1984年   538篇
  1983年   453篇
  1982年   463篇
  1981年   431篇
  1980年   406篇
  1979年   387篇
  1978年   355篇
  1977年   348篇
  1976年   276篇
  1975年   229篇
  1974年   217篇
  1973年   182篇
  1972年   147篇
  1968年   151篇
  1967年   164篇
  1966年   131篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
Iron Fortification of Flours in Venezuela   总被引:1,自引:0,他引:1  
This paper reviews a conference about the impact of the iron fortification program in Venezuela; it was presented at the Pan American Health Organization regional technical meeting: "Iron Fortification: Where Are We in Terms of Iron Compounds," held in Washington January 10–12, 2001. Some of the data presented were published in the American Journal of Clinical Nutrition , including stimulating results about the impact of fortification of precooked corn and white wheat flours, as well as the prevalence of anemia and iron deficiency in the Venezuelan population. This article reports results from three surveys carried out in 1997, 1998, and 1999 on the same age and socioeconomic group that had been evaluated in 1990, 1992, and 1994. This article also shows the impact of iron fortification programs and the influence of other factors on the prevalence of iron deficiency and anemia during the last 7 years.  相似文献   
6.
Background.Computers that collect data from patients and provide both patients and practitioners with printed feedback on a range of health risks are a tool for assisting general practitioners with preventive care. This study assessed the impact of computer-generated printed feedback on cervical screening among women who were underscreened for cervical cancer.Method.Female attenders at two Australian general practices were randomly allocated to Experimental or Control groups. Women in both groups completed a health risk survey on a touch screen computer prior to their consultation. Those in the Experimental group received printed pages summarizing their results, including their eligibility for cervical screening and last Pap test, for themselves and their doctor. The number and proportion of underscreened women who had a Pap test in the 6 months after completing the computer survey, as determined by pathology records, were examined.Results.Of the 679 participants, 139 were classified as underscreened on the basis of self-report (74 Experimental, 65 Control) and 272 on the basis of their pathology records (148 Experimental, 124 Control). Overall about one-third of women had a test in the 6-month period, and the differences between the groups were not significant for women overall (18–70 years) or for women 18–49 years. Among women 50–70 who were underscreened based on self-report, those receiving the printout were more likely to have a Pap test in the next 6 months (P< 0.05). This pattern was also evident, but did not reach statistical significance, for older women who were underscreened based on pathology records.Conclusions.We are unable to draw conclusions regarding the effectiveness of the computer system due to the modest proportions of women screened, the small numbers, and the fact that the computer survey may have created an intervention effect in the Control group. As the study suggests the computer system is acceptable to women and may be effective for encouraging screening among older women, further exploration of the system is desirable.  相似文献   
7.
8.
Ethanol account for a significant fraction of the energy intake of persons consuming even moderate amounts of alcohol. A recent study has shown that although alcohol does not reveal itself as a layer floating at the top of a drink, metabolically it behaves more like oil than sugar.  相似文献   
9.
10.
Study Objective . To characterize cytochrome P450 (CYP) 3A4 activity in premenopausal and postmenopausal women by evaluating the urinary 6-β-hydroxycortisokcortisol ratio. Design . Prospective study. Subjects . Thirteen premenopausal and 13 postmenopausal women who were healthy and not receiving drugs known to affect CYP3A4 activity. Interventions . Beginning on day 2 of menses, premenopausal women collected first morning urine samples every other day for a complete menstrual cycle. Postmenopausal women collected first morning urine every other day for 28 days. Measurements and Main Results . Mean weekly 6-β-hydroxycortisol:cortisol ratios did not differ during the phase (week) of the menstrual cycle. Daily ratios did not differ in postmenopausal women. No difference between premenopausal and postmenopausal women was found on comparing overall median ratios. Conclusion . Cytochrome P450 3A4 activity as measured by 6-β-hydroxy cortisol:cortisol ratio did not differ by week of menstrual cycle, suggesting no menstrual cycle-related changes. Menopause does not appear to be associated with differences in CYP3A4 activity, compared with premenopause.  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