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   971839篇
  免费   70295篇
  国内免费   1435篇
耳鼻咽喉   13349篇
儿科学   25430篇
妇产科学   24223篇
基础医学   138706篇
口腔科学   29150篇
临床医学   85666篇
内科学   190388篇
皮肤病学   19687篇
神经病学   76021篇
特种医学   38269篇
外国民族医学   135篇
外科学   157064篇
综合类   18913篇
现状与发展   1篇
一般理论   275篇
预防医学   66419篇
眼科学   22338篇
药学   75477篇
  3篇
中国医学   2183篇
肿瘤学   59872篇
  2018年   9596篇
  2017年   7518篇
  2016年   8298篇
  2015年   9415篇
  2014年   12845篇
  2013年   18851篇
  2012年   25853篇
  2011年   26851篇
  2010年   15901篇
  2009年   15231篇
  2008年   26353篇
  2007年   27442篇
  2006年   28245篇
  2005年   27156篇
  2004年   26293篇
  2003年   25137篇
  2002年   24665篇
  2001年   55882篇
  2000年   57809篇
  1999年   48056篇
  1998年   11256篇
  1997年   9917篇
  1996年   9984篇
  1995年   9334篇
  1994年   8649篇
  1993年   7937篇
  1992年   36343篇
  1991年   34807篇
  1990年   33578篇
  1989年   32687篇
  1988年   29826篇
  1987年   28970篇
  1986年   26988篇
  1985年   25832篇
  1984年   18398篇
  1983年   15626篇
  1982年   8126篇
  1981年   7080篇
  1979年   16318篇
  1978年   11046篇
  1977年   9431篇
  1976年   8215篇
  1975年   8955篇
  1974年   10853篇
  1973年   10237篇
  1972年   9691篇
  1971年   9148篇
  1970年   8710篇
  1969年   8194篇
  1968年   7501篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
This study qualitatively examined factors that influenced contraceptive choices in a sample of young, HIV-infected women. Individual qualitative interviews were conducted among 30 vertically and horizontally HIV-infected women (= 26 African American) from the ages of 14 to 24 years (Mean age = 20.9 years). We recruited sample groups with the following characteristics: (a) current contraceptive/condom use with ≥1 child (= 11); (b) current contraceptive/condom use with no children (= 12); and (c) no current contraceptive/condom use with no children (= 7). A semi-structured interview guide was used to ask participants about factors influencing past and current contraceptive choices. Individual interviews were digitally recorded and transcribed verbatim; analyses to identify core themes were informed by the Grounded Theoretical approach. Young, HIV-infected women did not identify their HIV serostatus or disease-related concerns as influential in their contraceptive decisions. However, they reported that recommendations from health-care providers and input from family and friends influenced their contraceptive choices. They also considered a particular method’s advantages (e.g., menstrual cycle improvements) and disadvantages (e.g., increased pill burden) when selecting a method. Findings suggested that HIV-infected young women’s contraceptive decisions were influenced by factors other than those related to their infection.  相似文献   
75.
76.
77.
78.
Vitamin D is responsible for multiple metabolic functions in humans. Rickets are the most common disease caused by vitamin D deficiency. It is caused by poor calcium intake resulting in poor serum-ionized calcium. The purpose of this study is to develop a rapid, sensitive, and feasible method to determine the 25-hydroxy-vitamin D3 (25(OH)D3) levels in blood samples for clinical assessment. In this study, gas chromatography coupled mass spectrometry with trimethylsilyl derivatization (TMS-GC-MS) is the most suitable protocol for quantitative analyses of 25(OH)D3. Performance of method was evaluated and compared with liquid chromatography and immunoassay. Method validation has been carried out with plasma specimens. The limit of quantitation of TMS-GC-MS method is 1.5 ppb with good linear correlation. Furthermore, the dietary intake and nutritional status of vegetarian and non-vegetarians in Taiwan were assessed by our validated method. As a result, this vitamin D nutrition survey demonstrates that most Taiwanese people have insufficient vitamin D. Due to dietary habits; the male vegans may have the highest risk of vitamin D deficiency.  相似文献   
79.
80.

Background

One daily dose of tacrolimus (QDT) improves adherence in kidney transplant (KT) recipients. A switch from twice-daily tacrolimus (BDT) to QDT showed similar efficacy and safety.

Methods

The aim of our study was to demonstrate the long-term efficacy and safety of switching from BDT to QDT in KT recipients. Preliminary results have already been published. Forty-one patients (34 men and 7 women), mean age at KT of 43.9 ± 12.7 years, underwent a 1:1 dose switch from BDT to QDT; the mean time from KT to switch was 36.6 ± 16.1 months. In our study population, 4 patients received a living donor KT and 2 received a second allograft.

Results

The mean follow-up was 86.8 ± 13 months from the switch and 126.2 ± 22.3 months from KT. Graft and patient survival rates were 90.2% and 95.1%, respectively. All patients maintained stable renal function during follow-up. During the first 3 months after the switch we observed a significant decrease in tacrolimus blood level (P = .0001). No significant differences were observed regarding tacrolimus dose before and after QDT introduction (P = not significant [NS]). Fourteen patients who stopped steroids under BDT treatment and 16 patients who stopped steroids after the switch are currently steroid-free.

Conclusion

Our study showed safety and efficacy in switching from BDT to QDT. After early (<1 year) dose adjustment, tacrolimus blood levels remained stable throughout follow-up. Moreover, QDT represented a valid alternative for patients showing steroid side effects.  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