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   1775篇
  免费   124篇
  国内免费   15篇
耳鼻咽喉   33篇
儿科学   56篇
妇产科学   12篇
基础医学   253篇
口腔科学   19篇
临床医学   167篇
内科学   317篇
皮肤病学   20篇
神经病学   99篇
特种医学   125篇
外科学   206篇
综合类   22篇
预防医学   183篇
眼科学   111篇
药学   99篇
中国医学   4篇
肿瘤学   188篇
  2023年   9篇
  2021年   23篇
  2020年   14篇
  2019年   22篇
  2018年   21篇
  2017年   26篇
  2016年   23篇
  2015年   31篇
  2014年   46篇
  2013年   65篇
  2012年   91篇
  2011年   76篇
  2010年   69篇
  2009年   54篇
  2008年   91篇
  2007年   92篇
  2006年   89篇
  2005年   83篇
  2004年   75篇
  2003年   82篇
  2002年   75篇
  2001年   61篇
  2000年   60篇
  1999年   63篇
  1998年   41篇
  1997年   32篇
  1996年   34篇
  1995年   20篇
  1994年   25篇
  1993年   15篇
  1992年   21篇
  1991年   41篇
  1990年   28篇
  1989年   32篇
  1988年   29篇
  1987年   19篇
  1986年   30篇
  1985年   32篇
  1984年   12篇
  1983年   10篇
  1982年   11篇
  1980年   8篇
  1979年   12篇
  1978年   15篇
  1977年   11篇
  1976年   9篇
  1975年   14篇
  1967年   7篇
  1966年   7篇
  1965年   8篇
排序方式: 共有1914条查询结果,搜索用时 343 毫秒
31.
BACKGROUND: Resistance to activated protein C (APC) is the most common hereditary defect in patients with venous thrombosis. There are conflicting reports on the prevalence of APC resistance in patients with arterial thrombosis, e.g. coronary arteries, compared to the APC resistance prevalence among the normal population. The prevalence of APC resistance in branch retinal artery occlusion (BRAO) and central retinal artery occlusion (CRAO) is unknown. PATIENTS AND METHODS: 29 consecutive patients with arterial retinal occlusions (BRAO, n = 12; CRAO, n = 17) were included in this prospective study over a 23-months-period. We searched for APC resistance, protein C or S deficiencies, as well as for acquired vascular risk factors. Factor-V-deficient plasma and genetic analysis with a PCR method were employed for APC resistance determination. Protein C and protein S activity were determined with functional tests. RESULTS: APC resistance was found in 3 of 29 patients (10.3%). Two of these patients had BRAO and one patient CRAO. Comparing this prevalence to the APC resistance prevalence within the normal population (9%), the difference was not statistically significant. 27 patients (93.1%) had one or more vascular risk factors (arterial hypertension = 19 [65.5%], hyperlipidaemia = 14 [48.2%], smoking = 7 [24.1%], diabetes mellitus = 5 [17.2%], carotid artery stenosis = 5 [17.2%]). CONCLUSIONS: We could not find an increased prevalence of APC resistance in patients with CRAO or BRAO when compared to the normal population.  相似文献   
32.
Retinal vascular occlusion and deficiencies in the protein C pathway.   总被引:3,自引:0,他引:3  
PURPOSE: To report abnormalities in the protein C pathway and other vascular occlusion risk factors in patients with retinal vascular occlusion. METHODS: In a study, we investigated 76 consecutive patients who had in-patient evaluation of venous or arterial retinal vascular occlusion. All patients underwent comprehensive tests for coagulation disorders including determinations of protein C, protein S, lupus anticoagulants, and resistance to activated protein C and were screened for vascular disease risk factors. Resistance to activated protein C was confirmed by a polymerase chain reaction method to detect the specific factor V R506Q mutation. For comparative purposes, we also screened 209 consecutive inpatients with deep vein thrombosis from the same geographic region for resistance to activated protein C as well as protein C and protein S deficiencies. RESULTS: Ten (29%) of 35 patients with central retinal vein occlusion (CRVO) had factor V R506Q mutation. The factor V R506Q mutation was detected in four (19%) of 21 patients with branch retinal vein occlusion. The higher frequency in factor V R506Q mutation compared with the expected 9% mutation prevalence in a white population was highly significant for the central retinal vein occlusion group but not for the branch retinal vein occlusion group. In all patients with resistance to activated protein C, the factor V R506Q mutation was detected; 16 were heterozygous, one homozygous. No cases of lupus anticoagulants, protein C, or protein S deficiencies were detected. Forty (19%) of 209 patients with deep vein thrombosis were carriers of the factor V R506Q mutation. CONCLUSIONS: The prevalence of the factor V R506Q mutation is similar in patients with central retinal vein occlusion and patients with deep vein thrombosis and represents a relevant risk factor. Screening for this mutation is therefore recommended in all patients with central retinal vein occlusion.  相似文献   
33.
BACKGROUND. This article describes the evaluation of a media-based weight loss and nutrition program. METHODS. Fifteen broadcasts were aired on a Chicago television news program over a three-week period in November of 1986. Some participants (n = 37) received the television program and an accompanying manual, and some (n = 37) received, in addition to the television and media interventions, encouragement to attend self-help groups dealing with obesity. RESULTS. Repeated measures analysis of variance tests were performed, and planned comparisons were conducted only if main effects were significant. At posttesting, those participants attending the self-help groups lost an average of more than nine pounds, whereas those provided only the television program and manual had decreased by less than a pound. Those attending the groups had significantly decreased their percent of dietary fat intake, significantly increased aerobic exercise, and had significantly more hopefulness, motivation, and stimulus control. DISCUSSION. The findings suggest that short-term mass media programs by themselves were probably not very effective, but when supplemented by a self-help manual and support groups may be able to produce significant short-term weight loss.  相似文献   
34.
35.
BACKGROUND: To evaluate the efficacy and toxicity of cisplatin/etoposide continuous infusion chemotherapy for cancer of unknown primary site in Taiwan, a region with a high prevalence of endemic viral infections. METHOD: Between April 1994 and February 1996, 20 patients with a diagnosis of CUPS were treated, including 15 males and five females, of average age 63.3 years (range 41-83 years). Continuous intravenous infusion of etoposide 80 mg/m2 and cisplatin 25 mg/m2 was given for 3 days every 3 weeks. Pretreatment tumor marker and viral serology studies were performed for baseline evaluation. Nearly two-thirds of the patients had poorly differentiated carcinoma. The average number of metastatic sites was 2.65 (range 1-4), with liver and lymph node involvement predominating. RESULTS: The overall response rate was 25% (95% CI 17.7-32.3%); 30.7% for poorly differentiated cancers and 25% for well differentiated cancers. Median survival was 4 months (range 1-12 months), 4.8 months for patients attaining partial response. Toxicity was moderate, grade 3 and 4 neutropenia occurred in 55% and grade 3 and 4 thrombocytopenia in 40%; other toxicities were mild. CA125 and CA199 were elevated in more than 50% of patients. Viral serology studies were not significantly different from those of the indigenous population. CONCLUSION: Etoposide and cisplatin combination chemotherapy has modest activity in patients with extensive CUPS and, at the schedule and dosage given, it is associated with moderate toxicity.   相似文献   
36.
The aim of this survey study was to derive the societal values of the general public for the EuroQol EQ-5D. Using the same protocol as previously used in the United Kingdom, we compared the German values with the British. In face-to-face interviews a sample of 339 individuals in northern Germany valued 15 different health states from a sample of 36 states. Values were derived using the York MVH protocol for time trade-off (TTO) and a visual analogue scale (VAS). Values for all 243 health states of the EQ-5D were estimated by a regression model. The VAS values revealed close a resemblance to the British VAS results. German TTO values were higher than the British. This was especially the case for the worse health states. The results suggest that the TTO values are more related to national variables than values derived by VAS. The use of the TTO values of this investigation makes it possible to anticipate these cultural differences in studies carried out in Germany.  相似文献   
37.
38.
39.
40.
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