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   12478篇
  免费   1255篇
  国内免费   34篇
耳鼻咽喉   197篇
儿科学   410篇
妇产科学   448篇
基础医学   1463篇
口腔科学   254篇
临床医学   1403篇
内科学   2394篇
皮肤病学   186篇
神经病学   1374篇
特种医学   583篇
外科学   1364篇
综合类   353篇
一般理论   6篇
预防医学   1441篇
眼科学   152篇
药学   987篇
中国医学   13篇
肿瘤学   739篇
  2023年   91篇
  2022年   91篇
  2021年   182篇
  2020年   160篇
  2019年   183篇
  2018年   232篇
  2017年   205篇
  2016年   233篇
  2015年   239篇
  2014年   393篇
  2013年   497篇
  2012年   580篇
  2011年   618篇
  2010年   358篇
  2009年   319篇
  2008年   541篇
  2007年   551篇
  2006年   506篇
  2005年   490篇
  2004年   463篇
  2003年   423篇
  2002年   422篇
  2001年   390篇
  2000年   409篇
  1999年   356篇
  1998年   185篇
  1997年   213篇
  1996年   189篇
  1995年   156篇
  1994年   153篇
  1993年   137篇
  1992年   228篇
  1991年   241篇
  1990年   292篇
  1989年   250篇
  1988年   218篇
  1987年   236篇
  1986年   212篇
  1985年   242篇
  1984年   167篇
  1983年   121篇
  1982年   99篇
  1981年   99篇
  1980年   86篇
  1979年   118篇
  1978年   105篇
  1975年   83篇
  1974年   103篇
  1973年   89篇
  1972年   86篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Summary The efficacy of cimetidine as a treatment that could reduce smoking in heavily dependent smokers has been determined. In a randomised, double-blind, double-crossover experiment, 43 heavy smokers were divided into two groups, one receiving cimetidine 400 mg orally three times a day, and the other receiving placebo for two weeks followed by the alternative treatment (placebo or cimetidine).No significant difference in the mean alveolar carbon monoxide, nicotine or cotinine levels was found between the two treatment groups compared to baseline. Since the alveolar carbon monoxide level reflects the intensity of smoking behaviour, the results suggest that no change in smoking behaviour occurred in the subjects.Contrary to our previous findings that cimetidine decreased the total body clearance of nicotine by 30% in a population of non-smokers, in the heavily dependent smokers, cimetidine did not appear to alter nicotine elimination. One possible explanation for the discrepancy is that tobacco smoking is known to induce nicotine metabolism and the induction might have offset any effect of cimetidine on nicotine elimination.Cimetidine does not appear to be a useful treatment leading to a reduction or cessation of cigarette smoking.  相似文献   
32.
33.
Background : A patient with a solitary pulmonary metastasis who had breast cancer in the past may benefit from pulmonary resection. Methods : Between 1984 and 1996, 17 patients underwent metastatectomy for metastatic breast cancer. There were 15 females and two males whose average age was 59 (range: 40–74 years). The median tumour-free interval after the primary breast-cancer operation was 5.1 years (range: 8 months-18.2 years). Sixteen patients had complete resections, which included six lobectomies and 10 lesser resections. Results : The postoperative mortality was nil and the morbidity rate was 6%. Follow-up was complete in all patients. Recurrent disease developed in four patients and two patients died of their disease. The 5-year survival was 62%. Conclusion : An aggressive surgical approach is warranted in patients with isolated resectable pulmonary metastases from breast cancer.  相似文献   
34.
During an exposure monitoring study, 78 saw maintenance tradesmen were randomly assigned to be interviewed about their exposures using one of two questionnaire formats: open-ended and partly prompted questions about five categories of materials; and detailed prompting about 75 agents. The more open-ended questionnaire elicited fewer exposure responses overall, but more responses about agents not included on the detailed questionnaire. Composite materials and trade name products were more frequently cited as exposures than individual metals or compounds. Validity of responses was ascertained using air measurements (individual metals) or observations of the employees (composite materials). Sums of sensitivities and specificities were very low (near 1.0) for most of the metals for both types of questionnaire. For composite materials, validity improved substantially. Sensitivities with the partly prompted format (0.44–0.85) were always lower than with detailed prompting (0.80–1.00). Specificities were usually, but not always, higher with partial prompting (0.66–0.92) than with detailed prompting (0.18–0.86). Selection of questionnaire format for an epidemiologic study would depend on the likely prevalence of exposure in controls and the effects of trade-offs in sensitivity and specificity.  相似文献   
35.
36.
37.
Holter technology has endured for more than 40 years, and proven to be a valuable adjunctive noninvasive diagnostic technology to record the ambulatory or long‐term electrocardiogram in the study of living creatures. During this span of time, many scientists, physicians, and innovators contributed to the development and evolution of Holter technology. This essay seeks to document a view of the history and evolution of the technology during that time, and concomitantly give recognition to the scientists, physicians, and engineers who contributed so greatly.  相似文献   
38.
39.
Plasma levels of cannabidiol (CBD) were ascertained weekly in 14 Huntington's disease patients undergoing a double-blind, placebo-controlled, crossover trial of oral CBD (10 mg/kg/day = about 700 mg/day) for 6 weeks. The assay procedure involved trimethylsilyl (TMS) derivatization of CBD and the internal standard delta-6-tetrahydrocannabinol (THC), capillary column gas chromatography, ion trap mass spectroscopy in positive ion chemical ionization mode using isobutane, and calculations of CBD levels based on peak ion intensity of the 387 M + H peak of delta-6-THC-TMS and the 459 M + H peak of CBD-2TMS. The sensitivity of the assay was about 500 pg/ml, and the precision was about 10-15%. Mean plasma levels of CBD ranged from 5.9-11.2 ng/ml over the 6 weeks of CBD administration. CBD levels averaged 1.5 ng/ml one week after CBD was discontinued, and were virtually undetectable thereafter. The elimination half-life of CBD was estimated to be about 2-5 days, and there were no differences between genders for half-life or CBD levels. Additionally, no plasma delta-1-THC, the major psychoactive cannabinoid of marijuana, was detected in any subject.  相似文献   
40.
T Khansur  A Kennedy 《Cancer》1991,67(8):2030-2032
Seven patients with advanced locoregional or metastatic squamous cell carcinoma of the skin were treated with cis-daimminedichloroplatin (cisplatin) and 5-fluorouracil (5-FU). Responses were seen in six of seven patients (three partial responses [PR] and three complete responses [CR]). One patient is alive and disease-free at 2 years. These results indicate that cisplatin and 5-FU is an effective combination regimen that should be used in future clinical trials in squamous cell carcinoma of the skin.  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