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   798篇
  免费   45篇
  国内免费   17篇
耳鼻咽喉   8篇
儿科学   31篇
妇产科学   6篇
基础医学   76篇
口腔科学   14篇
临床医学   102篇
内科学   196篇
皮肤病学   4篇
神经病学   66篇
特种医学   93篇
外科学   61篇
综合类   17篇
一般理论   2篇
预防医学   96篇
眼科学   9篇
药学   37篇
中国医学   1篇
肿瘤学   41篇
  2022年   7篇
  2021年   9篇
  2020年   6篇
  2019年   13篇
  2018年   12篇
  2017年   9篇
  2016年   5篇
  2015年   13篇
  2014年   18篇
  2013年   35篇
  2012年   39篇
  2011年   27篇
  2010年   33篇
  2009年   47篇
  2008年   21篇
  2007年   31篇
  2006年   42篇
  2005年   35篇
  2004年   44篇
  2003年   27篇
  2002年   22篇
  2001年   5篇
  2000年   23篇
  1999年   14篇
  1998年   35篇
  1997年   30篇
  1996年   21篇
  1995年   14篇
  1994年   19篇
  1993年   7篇
  1992年   12篇
  1991年   16篇
  1990年   11篇
  1989年   9篇
  1988年   15篇
  1987年   13篇
  1986年   17篇
  1985年   14篇
  1984年   10篇
  1983年   7篇
  1982年   16篇
  1981年   4篇
  1980年   6篇
  1978年   4篇
  1977年   5篇
  1975年   3篇
  1974年   5篇
  1968年   3篇
  1936年   2篇
  1930年   2篇
排序方式: 共有860条查询结果,搜索用时 15 毫秒
41.
Background We examined the link between functioning and psychological status among persons with chronic obstructive pulmonary disease (COPD), using measures of both general functional status and performance of life activities.Methods 334 persons with COPD were interviewed by telephone. Functioning was assessed with two measures of difficulty with specific types of activities (self-care, recreational activities/hobbies) and a general measure of functional status (SF-12 Physical Component Score (PCS)).Results About 16.2% of the sample had SF-12 Mental Component Score (MCS) scores indicative of psychological distress (MCS < 35). In separate regression models, difficulty with self-care and recreational activities was associated with an increased likelihood of distress (self-care: OR=2.9, 95%CI 1.3, 6.6; recreation: OR=7.5 [2.4, 23.7]), while PCS scores were not. In a model including all three predictors, difficulty with recreation was strongly associated with distress (OR=7.7 [2.1, 29.2]), difficulty with self-care was less strongly associated with distress (OR=2.1 [0.8, 5.5]), and PCS did not contribute significantly to the predictive ability of the model. However, low functioning as measured by the PCS was a significant risk factor for difficulty performing activities.Conclusions Measures of activity difficulty were independent predictors of psychological distress, while general physical function was not. Poor general physical function was a risk factor for activity difficulties, suggesting an indirect relationship between low PCS and psychological distress, with activity difficulties as the intermediate variable.  相似文献   
42.
We conducted a study among healthcare workers (HCWs) exposed to patients with severe acute respiratory syndrome (SARS) before infection control measures were instituted. Of all exposed HCWs, 7.5% had asymptomatic SARS-positive cases. Asymptomatic SARS was associated with lower SARS antibody titers and higher use of masks when compared to pneumonic SARS.  相似文献   
43.
OBJECTIVE: As opposed to traditional food based delivery we examined the efficacy of ingesting encapsulated phytosterol esters on indices of lipid health in hypercholesterolemic adults. METHODS: We performed a randomized, double-blinded, parallel-group, placebo-controlled, clinical intervention examining 54 men and women (20-70 y of age) with a low-density lipoprotein cholesterol (LDL-C) level > or =3.33 mmol/L. Participants were not taking cholesterol-lowering medications. Treatment consisted of ingesting 2.6 g of encapsulated phytosterol esters (n = 25) or a matching placebo (n = 29) for 12 wk. RESULTS: Total cholesterol (TC) levels at baseline (mean +/- SD) were 6.29 +/- 0.7 mmol/L in the phytosterol group and 6.00 +/- 0.7 mmol/L in the placebo group. Baseline LDL-C levels were 4.27 +/- 0.7 mmol/L in the treatment group and 4.00 +/- 0.8 mmol/L in the placebo group. Analysis of variance and Tukey's least significant difference post hoc analyses revealed a significant within-group reduction in TC (-0.23 +/- 0.4 mmol/L, P < 0.05) and LDL-C (-0.22 +/- 0.5 mmol/L, P < 0.05) for the phytosterol treatment group. Mean reductions in TC and LDL-C were greater than placebo (P < 0.05). Percentages of change from baseline for TC were -3.52% (95% confidence interval -6.44 to -0.40) for phytosterol treatment and 2.64% (95% confidence interval 0.30-5.60) for placebo. Those for LDL-C were -5.00% (95% confidence interval -9.92 to -0.08) for phytosterol and 4.89 (95% confidence interval 0.24-9.5) for placebo. No other significant effects were observed. CONCLUSION: Encapsulated phytosterol ester ingestion appears to positively modulate LDL-C. Given that the reduction in LDL-C was not as extensive as in food-based trials, future investigations should examine potential timing and dose issues relative to encapsulated delivery.  相似文献   
44.
The extent of health effects and exposure to environmental contaminants among workers and residents indirectly affected by the September 11, 2001, attack on the World Trade Center (WTC) is unknown. The objective of this study was to evaluate concerns related to health effects and occupational exposures three months after the WTC disaster among a population of employees working in a building close to the disaster site. A cross-sectional questionnaire survey was performed of Federal employees working near the WTC site in New York City (NYC) and a comparison group of Federal employees in Dallas, Texas. An industrial hygiene evaluation of the NYC workplace was conducted. Constitutional and mental health symptoms were reported more frequently among workers in NYC compared to those in Dallas; level of social support was inversely related to prevalence of mental health symptoms. Post-September 11th counseling services were utilized to a greater degree among workers in NYC, while utilization of other types of medical services did not differ significantly between the groups. No occupational exposures to substances at concentrations that would explain the reported constitutional symptoms were found; however, we were unable to assess potential occupational exposures in the time immediately after the WTC disaster. There is no evidence of ongoing hazardous exposure to airborne contaminants among the workers surveyed. Specific causes of reported constitutional health symptoms have not been determined. Health care providers and management and employee groups should be aware of the need to address mental health issues as well as constitutional symptoms among the large number of workers in the NYC area who have been indirectly affected by the WTC disaster.  相似文献   
45.
Dysphagia as the Sole Manifestation of Bilateral Strokes   总被引:2,自引:0,他引:2  
Dysphagia can be caused by a host of factors, most of which are structural or functional. However, despite extensive evaluations, a certain number of patients have unexplained dysphagia. We present an extremely unusual case whereby a patient with an acute left hemispheric cerebral vascular accident presents with dysphagia as his sole complaint and after extensive neurological, gastroenterological, and radiographic examinations is found to have cricopharyngeal dysfunction. The etiology of this defect was not at all clinically apparent and, ultimately, magnetic resonance imaging (MRI) was performed which revealed a chronic infarction of the right frontal lobe and a smaller acute infarction in the same location of the left. This case demonstrates that swallowing disorders may be the sole presentation of stroke and that, if extensive evaluations of such patients fail to yield an etiology, one must strongly consider MRI as a tool for diagnosis, even if a CT scan is negative.  相似文献   
46.
The potential spread of the bacteria in aerosols emphasizes the familiar triad--gloves, masks and eyewear--for all operative procedures.  相似文献   
47.
48.
49.
Therapeutic embolization angiography for extra-axial lesions in the head   总被引:1,自引:0,他引:1  
Percutaneous transcatheter arterial embolization has played an increasingly important role in the management of vascular lesions in the head. Embolization can promote thrombosis within vascular tumors and malformations, reduce bleeding and decrease the need for transfusion intraoperatively, and facilitate surgical approaches to otherwise unresectable lesions. It is important for the clinician to be aware of this interventional technique because many of the patients who are considered for embolization are triaged through several different clinical areas, and much can be gained from the collaboration of the clinician, the surgeon, and the angiographer. We performed 31 therapeutic particulate embolization procedures for extra-axial head lesions in 23 patients by using flow-directed techniques. Of these procedures, 11 resulted in vascular occlusion and 15 resulted in 80 to 95% obstruction, as demonstrated by angiography. In 14 patients, embolization was performed preoperatively both to decrease blood loss and to occlude inaccessible or unresectable portions of a lesion. In nine patients, embolization was the sole means of treatment for occluding an abnormal vascular shunt. Two patients (9%) experienced a minor transient neurologic change after the procedure.  相似文献   
50.
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