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   2312篇
  免费   143篇
  国内免费   5篇
耳鼻咽喉   14篇
儿科学   137篇
妇产科学   38篇
基础医学   241篇
口腔科学   21篇
临床医学   185篇
内科学   886篇
皮肤病学   31篇
神经病学   97篇
特种医学   68篇
外科学   281篇
综合类   38篇
一般理论   1篇
预防医学   81篇
眼科学   34篇
药学   193篇
中国医学   12篇
肿瘤学   102篇
  2023年   13篇
  2022年   27篇
  2021年   67篇
  2020年   34篇
  2019年   33篇
  2018年   45篇
  2017年   35篇
  2016年   32篇
  2015年   35篇
  2014年   52篇
  2013年   64篇
  2012年   110篇
  2011年   101篇
  2010年   80篇
  2009年   58篇
  2008年   99篇
  2007年   104篇
  2006年   86篇
  2005年   98篇
  2004年   115篇
  2003年   70篇
  2002年   76篇
  2001年   86篇
  2000年   111篇
  1999年   72篇
  1998年   25篇
  1997年   24篇
  1996年   22篇
  1995年   23篇
  1994年   14篇
  1993年   17篇
  1992年   66篇
  1991年   49篇
  1990年   40篇
  1989年   47篇
  1988年   39篇
  1987年   42篇
  1986年   42篇
  1985年   55篇
  1984年   39篇
  1983年   26篇
  1981年   12篇
  1980年   11篇
  1979年   21篇
  1978年   11篇
  1975年   12篇
  1974年   15篇
  1973年   13篇
  1971年   11篇
  1968年   10篇
排序方式: 共有2460条查询结果,搜索用时 15 毫秒
51.
The sensitivity of ST-segment depression on the electrocardiogram during exercise is influenced by the level of effort. Whether such is the case with thallium-201 imaging (initial defect or redistribution) has not been established. Accordingly, the prevalence of these parameters was evaluated in 288 patients (age 59 +/- 10 years, 88% men) with coronary artery disease who underwent both exercise thallium-201 imaging and coronary angiography within 3 months of each other: 159 had a prior myocardial infarction, 72 had 1-vessel, and 216 had multivessel disease. The degree of effort was evaluated by 3 criteria: (1) percentage of maximal predicted heart rate (less than or equal to 65, greater than 65 to 85, greater than 85%); (2) workload during exercise (less than or equal to 4, greater than 4 to 8, greater than 8 METs); and (3) duration of exercise (less than or equal to 3, greater than 3 to 6, greater than 6 minutes). The prevalence of defects on initial images was higher than both redistribution on delayed images and ST-segment depression on the electrocardiogram (p less than 0.01). The overall prevalence of initial defects remained the same for all levels of effort and was not influenced by the presence or absence of a prior infarction. However, it decreased in patients with 1-vessel disease who exercised to higher workloads. The prevalence of redistribution on delayed thallium-201 images was higher than that of ST-segment depression on the electrocardiogram (p less than 0.01), except at higher levels of effort where they were similar.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
52.
Intracoronary stents are traditionally considered to be contraindicated in presence of thrombus. However recent advances in stent deployment technique have reduced the risk of stent thrombosis. We report the placement of a stent in a thrombus laden saphenous vein graft to the posterior descending artery. Three months later the stent site was patent with severe stenosis with thrombus in another graft which was also stented. Intracoronary stents should be considered in patients with complex lesion even in presence of intraluminal thrombus.  相似文献   
53.
BACKGROUND: We performed a case-control study to estimate lipid-cholesterol fractions in patients with coronary heart disease and compared them with population-based controls. METHODS AND RESULTS: A total of 635 newly diagnosed patients with coronary heart disease (518 males and 117 females) and 632 subjects (346 males and 286 females) obtained from an ongoing urban coronary heart disease risk factor epidemiological study were evaluated. Age-specific lipid values (total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides, and total:high-density lipoprotein cholesterol ratio) were compared using the t-test. Age-adjusted prevalence of dyslipidemia as defined by the US National Cholesterol Education Program was compared using the Chi-square test. In all the age groups, and in both males and females, levels of total and low-density lipoprotein cholesterol were not significantly different. In males, the high-density lipoprotein cholesterol (mg/dl) was significantly lower in patients with coronary heart disease as compared to controls in the age groups 30-39 years (35.1+/-11 v. 43.7+/-9), 40-49 years (39.0+/-10 v. 47.1+/-8), 50-59 years (38.9+/-11 v. 43.8+/-9) and 60-69 years (38.6+/-11, v. 42.8+/-7) (p<0.05). In females, high-density lipoprotein cholesterol was less in the age groups 30-39 years (30.2+/-9 v. 40.7+/-9), 50-59 years (39.7+/-12 v. 44.7+/-8) and 60-69 years (35.6+/-11 v. 42.2+/-9). The level of triglycerides was significantly higher in male patients in the age groups 40-49 years (195.3+/-96 v. 152.8+/-78), 50-59 years (176.7+/-76 v. 162.9+/-97), 60-69 years (175.5+/-93 v. 148.1+/-65) and >70 years (159.8+/-62 v. 100.0+/-22); and in female patients in the age group 30-39 years (170.8+/-20 v. 149.9+/-9) (p<0.05). The total:high-density lipoprotein cholesterol ratio was significantly higher in all age groups in male as well as female patients with coronary heart disease (p<0.05). CONCLUSIONS: An age-adjusted case-control comparison showed that the prevalence of hypertension, diabetes, high total cholesterol (> or =200 mg/dl) (males 48.8% v. 20.2%; females 59.8% v. 33.4%) and high low-density lipoprotein cholesterol (> or =130 mg/dl) (males 42.1% v. 15.0%; females 52.1% v. 31.0%) was significantly more in cases than in controls. The prevalence of low high-density lipoprotein cholesterol (<35 mg/dl) (males 39.6% v. 6.2%; females 39.3% iv 9.5%), high total:high-density lipoprotein ratio (> or = 5.0) and high triglycerides (> or =200 mg/ dl: males 39.6%, v. 10.2%; females 17.1% v. 11.9%) was also significantly higher in cases (p<0.05).  相似文献   
54.
Clinical manifestations of aortoarteritis (Takayasu's arteritis) are varied, depending on the involved segment of the aorta and its branches. A case of a young Indian woman with aortoarteritis presenting primarily with hypoparathyroidism is reported. Aortogram showed total occlusion of the arch arteries. To the best of our knowledge, the occurrence of hypoparathyroidism in aortoarteritis has not been reported. Possible mechanisms of such an involvement are discussed.  相似文献   
55.
56.
The current clinical practice of stent implantation has changed over the last few years. We analysed the incidence and time course of stent thrombosis in patients undergoing successful coronary angioplasty and stenting over the last three years. All the patients were treated with aspirin and ticlopidine. A total of 13 patients experienced stent thrombosis. The mean age was 52+/-12 years; 12 were smokers and 10 had a recent history of myocardial infarction. None of these patients had received abciximab. The median time from stent implantation to stent thrombosis was 10 hours, with all the stent occlusions occurring within 18 hours of stent implantation procedure. All the patients underwent a repeat intervention at a median time of 30 minutes after the clinical suspicion of stent occlusion. On follow-up of 1 to 24 months, three patients developed reocclusion. In the present era of coronary angioplasty and stenting, when interventional procedures are not pre-planned and patients are treated with aspirin and ticlopidine or clopidogrel at the time of stent implantation, the incidence of stent thrombosis is low; it is seen mainly in patients with recent myocardial infarction, majority of them being smokers, and occurs within 18 hours in all the patients.  相似文献   
57.
58.
59.
A filariasis survey carried out about eight years after achieving zero microfilaria (mf) rates following administration of diethylcarbamazine (DEC) medicated salt in the Kani hill tribe settlements in Quilon and Thiruvananthapuram districts of Kerala State revealed that there was no reappearance of Brugia malayi infection in the experimental areas. Mf rates were maintained at zero level in the experimental villages, while in the control villages, 2.9 per cent mf positives were observed. Mansonia (Mansonioides) uniformis dissected did not reveal filarial infection. It is concluded that DEC medicated salt regime in the experimental areas of Kani hill tribe settlements has been successful in effectively interrupting B. malayi transmission. Pilot studies in other B. malayi endemic areas of India using DEC medicated salt regime with the objective of eliminating B. malayi transmission are advocated, since the parasite has a restricted distribution in India and is already showing a declining trend.  相似文献   
60.
Real-time PCR testing for blaKPC, blaNDM, blaVIM, blaIMP, and blaCTX-M was performed on rectal swabs obtained from residents of two long-term acute-care facilities. While blaKPC was detected in 69/102 swabs (67.6%), testing for four other targets increased the positivity rate for a broad-spectrum β-lactamase to 73.5% (McNemar''s P = 0.03).  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