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   2306篇
  免费   155篇
  国内免费   3篇
耳鼻咽喉   5篇
儿科学   77篇
妇产科学   47篇
基础医学   353篇
口腔科学   43篇
临床医学   341篇
内科学   510篇
皮肤病学   39篇
神经病学   266篇
特种医学   38篇
外科学   172篇
综合类   14篇
一般理论   1篇
预防医学   225篇
眼科学   43篇
药学   124篇
中国医学   6篇
肿瘤学   160篇
  2023年   12篇
  2022年   13篇
  2021年   42篇
  2020年   31篇
  2019年   44篇
  2018年   54篇
  2017年   43篇
  2016年   48篇
  2015年   80篇
  2014年   106篇
  2013年   117篇
  2012年   171篇
  2011年   168篇
  2010年   80篇
  2009年   87篇
  2008年   158篇
  2007年   154篇
  2006年   147篇
  2005年   140篇
  2004年   173篇
  2003年   148篇
  2002年   151篇
  2001年   18篇
  2000年   18篇
  1999年   12篇
  1998年   33篇
  1997年   32篇
  1996年   14篇
  1995年   20篇
  1994年   16篇
  1993年   17篇
  1992年   10篇
  1991年   6篇
  1990年   9篇
  1989年   8篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   8篇
  1984年   9篇
  1983年   5篇
  1982年   6篇
  1981年   6篇
  1980年   6篇
  1979年   3篇
  1978年   6篇
  1974年   5篇
  1972年   3篇
  1965年   1篇
  1913年   2篇
排序方式: 共有2464条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
The use of livers from anti-hepatitis B core (HBc) positive donors can alleviate donor shortage. Nineteen of 367 (6%) adults receiving anti-HBc positive allografts [three were hepatitis B antigen (HBsAg) negative, hepatitis B antibody (HBsAb) positive; four were HBsAg positive and 12 were not exposed to hepatitis B viral (HBV) infection] were retrospectively reviewed. In HBsAg negative recipients, immunoprophylaxis (IP) was guided by viral serology and immunohistochemistry (IH) of day 0 and day 7 liver biopsies. If IH was negative, IP was stopped. None of three HBsAg negative, HBsAb positive recipients infected; one (replicating) of four HBsAg positive recipients reinfected and seven of eight (87.5%) HBsAg, HBsAb negative recipients, who did not receive long-term IP, infected after a median time of 2 years (range 1-5); one patient died of liver failure. Four HBsAg, HBsAb negative recipients, receiving life-long IP, remained infection free. Anti-HBc positive donor livers must be directed selectively first to HBsAg positive recipients, next to recipients having HBV antibodies and finally to HBV-naive recipients. Identification of both donor and recipient risk factors for HBV infection before transplantation allows indiscriminate use of antiviral prophylaxis. The necessity for IP therapy should be guided by HBV-DNA testing of donor liver tissue and serum. IH of early liver biopsies is an unreliable marker for predicting antiviral treatment requirements.  相似文献   
7.
The purpose of our study was to determine the prevalence of protein-calorie malnutrition (PCM), ocular diseases, and vitamin A deficiency in preschool children selected at random in a rural zone of the groundnut belt of Senegal. The prevalence of PCM was 37.1% (95% CI 33.8-40.2%) according to the Waterlow classification, with a majority of stunting, and prevalence of hypovitaminosis A was estimated to be 11.4% (95% CI 9.3-13.5%) by using impression cytology. Furthermore, 19.4% (95% CI 15.8-22.0%) of the children might be defined at risk of deficiency. The prevalence of Bitot's spots was equal to 0.2% (95% CI 0.03-0.9%). A problem of PCM associated with a health-endangering vitamin A deficiency existed.  相似文献   
8.
Objective: To determine if uncooked cornstarch, as part of the evening snack, can avert nocturnal hypoglycemia in type 1 diabetes. Research Design and Methods: Fifty-one campers and counselors at the American Diabetes Association Camp in San Bernardino, CA were randomly assigned to receive 5 g of uncooked cornstarch as part of the 21:00 evening snack vs. a standard snack of equivalent carbohydrate content. Each snack was given for five nights and the participants and medical personnel were blinded as to assignment. Midnight and 07:00 finger stick blood glucose levels were compared with values <60 mg/dl defined as hypoglycemia and values >250 mg/dl defined as hyperglycemia. Results: There were 218 midnight and 222 07:00 values for comparison. There were six episodes of hypoglycemia at midnight and nine episodes of hypoglycemia at 07:00 for the cornstarch snack nights vs. 30 hypoglycemia episodes at midnight and 21 at 07:00 for the standard snack nights (P < 0.001 and < 0.05, respectively). There was no difference in the number of hyperglycemic events at midnight or 07:00 for the cornstarch vs. standard snack nights. At midnight, 12% of campers had hypoglycemia after the cornstarch snack vs. 46% after the standard snack (P < 0.001), and at 07:00, 16% had hypoglycemia after cornstarch vs. 26% after the standard snack (P = 0.327). Conclusions: These data suggest that uncooked cornstarch, as part of the evening snack, can diminish the nighttime and morning hypoglycemia associated with type 1 diabetes, without causing hyperglycemia.  相似文献   
9.
BACKGROUND: Emerging evidence suggests that type 2 diabetes may be related to diminished cognition, but little data are available directly regarding the role of insulin levels. OBJECTIVE: The objective of this prospective cohort study was to examine the relation of insulin secretion to cognitive function among men without diabetes. SETTING: The study setting was the Physicians' Health Study-U.S. male physicians. PARTICIPANTS: Three hundred sixty-seven men who provided blood samples in 1982, when they had no lifetime history of diabetes and ranged in age from 47-65 years (mean age: 57 years). MEASUREMENTS: The authors assayed plasma C-peptide, reflecting insulin secretion, in the stored blood samples. Beginning in 2001, an average 18 years after blood collection, the authors administered telephone interviews, including tests of general cognition (Telephone Interview of Cognitive Status [TICS]), verbal memory, and category fluency. The authors used regression models to estimate mean differences in cognitive performance across levels of C-peptide controlling for a wide variety of potential confounding factors. RESULTS: On the TICS, men in the top tertile of C-peptide performed significantly worse than those in the bottom (multivariable-adjusted mean difference: -1.01 points, 95% confidence interval: -1.78 to -0.24); this apparent impact of C-peptide on cognition was equivalent to the cognitive differences the authors observed between men 6 years apart in age. Performance on the global score (combining results from all the individual tests) and verbal memory score (combining results from four tests of verbal memory) appeared lower among men in the highest C-peptide tertile, but results were not statistically significant. CONCLUSION: Higher midlife insulin secretion may be related to decreased later-life cognitive function, even among men without diabetes.  相似文献   
10.
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