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   878篇
  免费   47篇
  国内免费   48篇
耳鼻咽喉   2篇
儿科学   47篇
妇产科学   27篇
基础医学   84篇
口腔科学   38篇
临床医学   95篇
内科学   211篇
皮肤病学   16篇
神经病学   31篇
特种医学   116篇
外科学   118篇
综合类   10篇
一般理论   1篇
预防医学   63篇
眼科学   3篇
药学   59篇
  1篇
中国医学   1篇
肿瘤学   50篇
  2023年   8篇
  2022年   11篇
  2021年   8篇
  2019年   10篇
  2018年   15篇
  2017年   13篇
  2016年   15篇
  2015年   23篇
  2014年   23篇
  2013年   42篇
  2012年   23篇
  2011年   25篇
  2010年   24篇
  2009年   23篇
  2008年   15篇
  2007年   46篇
  2006年   25篇
  2005年   18篇
  2004年   10篇
  2003年   15篇
  2002年   15篇
  2001年   15篇
  2000年   17篇
  1999年   20篇
  1998年   48篇
  1997年   52篇
  1996年   62篇
  1995年   47篇
  1994年   30篇
  1993年   33篇
  1992年   8篇
  1991年   16篇
  1990年   11篇
  1989年   19篇
  1988年   29篇
  1987年   26篇
  1986年   15篇
  1985年   18篇
  1984年   8篇
  1983年   9篇
  1982年   10篇
  1981年   9篇
  1980年   11篇
  1978年   5篇
  1977年   8篇
  1975年   5篇
  1971年   4篇
  1968年   7篇
  1967年   4篇
  1966年   4篇
排序方式: 共有973条查询结果,搜索用时 0 毫秒
61.
62.
PURPOSE: In this report, we retrospectively evaluate the effect of a laparoscopic approach in the diagnosis and treatment of acute abdominal pain in patients with suspected peritonitis. PATIENTS AND METHODS: We evaluated the clinical records of patients admitted to our institution between January 1995 and July 2001 with a diagnosis of acute abdomen and suspected peritonitis. RESULTS: Ninety four of 229 patients underwent diagnostic laparoscopy. In this series, 83 (88.3%) of the cases were successfully treated by emergent laparoscopy for an acute abdomen. Eleven (11.7%) required conversion to an open laparotomy procedure. Overall, the preoperative diagnosis was confirmed by laparoscopy in 67 (71.27%) of the cases. It was not confirmed in 27 (28.73%). Postoperative mortality was 4.25%. Morbidity was 8.5%. DISCUSSION: Data reported in the literature establish that laparoscopy offers adequate visualization of the entire abdomen and pelvic cavity in the diagnosis of an abdomen acute secondary to peritonitis. In this series, laparoscopy confirmed the diagnosis in 97.8% of the patients, and minimally invasive treatment was achieved in 88.3% of the cases. Female patients with gynecologic disease particularly benefitted from a laparoscopic approach, which permitted the correct evaluation of this condition and may have prevented unnecessary laparotomy. We believe that laparoscopy is an accurate modality for the diagnosis and treatment of patients with an acute abdomen and suspected peritonitis when the diagnosis cannot be clearly made by physical examination and noninvasive methods.  相似文献   
63.
64.
65.
Understanding diet and energy balance as risk factors for breast, colon, and other cancers requires information on the contribution of each factor and of interactions among factors to cancer risk. Rodent models for breast cancer provide extensive data on effects of dietary fat and calories, energy balance, body weight gain, and physical activity on tumor development. Analyses of the combined data from many studies have shown clearly that quality and quantity of dietary fat and energy balance contribute independently to increased mammary gland tumorigenesis. These findings were seen in female rats fed diets high in fat (35-40% of calories) compared to rats fed control diets, with approximately 10% of calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46, 215-223). The methods used permit comparison of experimental and epidemiological data, and they may be useful in extrapolating between species and developing public health recommendations. In addition to the contributions of lifetime-diet composition, intake, energy balance, and physical activity to cancer risk, there are questions about the timing and duration of alterations in these factors and about the "dose-response" characteristics of cancer risk to the factors. Endocrine mechanisms may be significant in mammary gland tumor risk, but experimental and epidemiological data indicate that cancers at other sites, such as colon and liver, also are influenced by the factors listed. Other diet and lifestyle factors that influence energy, or specifically fat, metabolism may also affect risk for cancers that are promoted by increased intake of fat and calories. Studies of separate and interactive effects of dietary fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using adjustment of carcinogenesis endpoints for body weight, tumor burden, and latency, they were found to be related to weight gain within treatment groups in 2 of 3 experiments.   相似文献   
66.

Background

Postal questionnaires are an economical and simple method of data collection for research purposes but are subject to non-response bias. Several studies have explored the effect of monetary and non-monetary incentives on response. Recent meta-analyses conclude that financial incentives are an effective way of increasing response rates. However, large surveys rarely have the resources to reward individual participants. Three previous papers report on the effectiveness of lottery incentives with contradictory results. This study aimed to determine the effect of including a lottery-style incentive on response rates to a postal health survey.

Methods

Randomised controlled trial. Setting: North and West Birmingham. 8,645 patients aged 18 or over randomly selected from registers of eight general practices (family physician practices). Intervention: Inclusion of a flyer and letter with a health questionnaire informing patients that returned questionnaires would be entered into a lottery-style draw for £100 of gift vouchers. Control: Health questionnaire accompanied only by standard letter of explanation. Main outcome measures: Response rate and completion rate to questionnaire.

Results

5,209 individuals responded with identical rates in both groups (62.1%). Practice, patient age, sex and Townsend score (a postcode based deprivation measure) were identified as predictive of response, with higher response related to older age, being female and living in an area with a lower Townsend score (less deprived).

Conclusion

This RCT, using a large community based sample, found that the offer of entry into a lottery style draw for £100 of High Street vouchers has no effect on response rates to a postal health questionnaire.  相似文献   
67.
68.
69.
70.
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