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   1344篇
  免费   57篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   24篇
妇产科学   5篇
基础医学   59篇
口腔科学   18篇
临床医学   91篇
内科学   416篇
皮肤病学   5篇
神经病学   64篇
特种医学   101篇
外科学   140篇
综合类   37篇
预防医学   130篇
眼科学   229篇
药学   41篇
肿瘤学   47篇
  2022年   5篇
  2021年   15篇
  2020年   8篇
  2019年   12篇
  2018年   16篇
  2017年   15篇
  2016年   13篇
  2015年   23篇
  2014年   23篇
  2013年   61篇
  2012年   64篇
  2011年   65篇
  2010年   60篇
  2009年   45篇
  2008年   63篇
  2007年   68篇
  2006年   74篇
  2005年   79篇
  2004年   52篇
  2003年   42篇
  2002年   59篇
  2001年   47篇
  2000年   46篇
  1999年   38篇
  1998年   30篇
  1997年   23篇
  1996年   22篇
  1995年   15篇
  1994年   27篇
  1993年   17篇
  1992年   22篇
  1991年   19篇
  1990年   30篇
  1989年   24篇
  1988年   14篇
  1987年   16篇
  1986年   12篇
  1985年   12篇
  1984年   11篇
  1982年   5篇
  1981年   6篇
  1980年   11篇
  1978年   8篇
  1977年   6篇
  1975年   5篇
  1973年   7篇
  1971年   7篇
  1968年   5篇
  1965年   4篇
  1947年   5篇
排序方式: 共有1408条查询结果,搜索用时 10 毫秒
61.
BACKGROUND: Ring melanoma of the ciliary body is a rare variant of uveal melanoma that has a poor prognosis. Only isolated cases have been reported in the literature. METHODS: A retrospective review of the clinical features, management, histopathology, and prognosis of 23 consecutive patients with ring melanoma of the ciliary body was performed. RESULTS: Of 8,800 patients with uveal melanoma treated on the Oncology Service at Wills Eye Hospital over a 25-year period, only 23 patients (0.3%) were found to have ring melanoma of the ciliary body. The mean patient age was 59 years (median, 63 years; range, 8-81 years). The only visual symptom was blurred vision in 17 patients (74%), and the other six patients (26%) were asymptomatic. At the initial presentation elsewhere, melanoma was recognized in 13 cases (57%). In the remaining 10 cases (43%), the initial clinical diagnosis was glaucoma in three (13%), iris nevus in three (13%), cataract in two (9%), ciliary body detachment in one (4%), and iridocyclitis in one (4%). The patients were observed elsewhere for a mean of 3 months before the diagnosis of melanoma was suspected and referral to Oncology Service was made. On examination, the tumor involved a mean of eight clock hours of the ciliary body. Seven patients (30%) had complete circumferential (360 degrees) involvement of the ciliary body, and 16 (70%) had incomplete (180-360 degrees) ring involvement. The mean tumor thickness was 8 mm. Associated findings included neovascularization of the iris in one case (4%), shallow anterior chamber in 11 (48%), anterior chamber inflammation in five (22%), cataract in nine (39%), lens indentation in eight (35%), and lens subluxation in three (13%). A prominent episcleral (sentinel) vessel (17 cases, 74%), multilobulation of the mass (19 cases, 83%), blockage of light on transillumination (23 cases, 100%), and ultrasonographic hollowness with intrinsic pulsations (23 cases, 100%) were important features differentiating this tumor from simulating conditions. The tumor was managed with enucleation in all 23 patients. Histopathologic studies revealed epithelioid cell-type melanoma in two patients (9%), mixed cell-type in 17 (74%), and spindle cell-type in four (17%). Extraocular extension was present in eight patients (35%). Metastasis developed in 12 of 23 patients (52%) after a mean follow-up of 55 months. CONCLUSIONS: Ring melanoma of the ciliary body is a rare tumor that can remain hidden from ophthalmoscopic examination. Certain features, such as prominent episcleral sentinel vessels, multilobulation of the mass, light blockage on transillumination, and ultrasonographic hollowness with intrinsic vascular pulsations, suggest the diagnosis. The life prognosis is poor.  相似文献   
62.
Two patients had undergone double-plate Molteno shunt implantation. Both patients required surgical revision, the first at 41 months and the second at 8 months postoperatively, because of a failure of previously functioning tube shunts caused by blockage of the external ostium and intraluminal invasion of the tube by fibrous tissue. At the time of surgical revision, fibrous tissue extended down the lumen of the tube, occluding its external ostium. After excision of this tissue, both shunts became fully functional. When functioning aqueous shunts fail and there is no evidence of a bleb over the shunt reservoir or blockage of the internal ostium, ingrowth of fibrous tissue into the external ostium should be considered as a potential cause, especially if a ripcord or Latina suture has been left in place.  相似文献   
63.
PURPOSE: To report a clinicopathologic correlation of an unusual benign lymphocytic iris mass in a patient who had no systemic lymphoproliferative disease. METHODS: Case report. RESULTS: A 49-year-old man developed a circumscribed, tan lesion in his left iris. The lesion was suspected clinically to be an atypical iris melanoma. Histopathologic studies of the resected mass revealed a solid tumor that was comprised of lymphocytes and histiocytes. Immunohistochemical studies identified that most of the cells were T lymphocytes. The histopathologic diagnosis was atypical lymphoid infiltrate. Workup for systemic lymphoma and Epstein-Barr virus infection was negative. CONCLUSION: Lymphoid infiltrate can manifest as a solitary mass that can simulate an iris melanoma.  相似文献   
64.
We assessed patients' health-related quality of life after myocardial infarction and identified related variables. Clinical data were obtained retrospectively from medical records of consecutive patients admitted to a Midwestern university-affiliated medical center with diagnosis of myocardial infarction from July 1999-July 2000. Telephone interviews 7 months after discharge were made to administer the Short Form-12 (SF-12) and obtain patient, disease, drug, and intervention data. Complete information was obtained from 200 patients (mean age 63.4 +/- 13.1 yrs, 68% men). The mean Physical Component Summary (PCS)-12 score was 40.6 +/- 12.0, and the mean Mental Component Summary (MCS)-12 score was 52.1 +/- 10.0. Based on univariate analyses, low PCS-12 scores were associated with women; non-Q-wave infarctions; greater number of illnesses; history of myocardial infarction, chronic heart failure (CHF), transient ischemic attack (TIA), renal disease, peripheral vascular disease, or percutaneous coronary intervention (PCI); rehospitalization during the interim period; and unscheduled PCI since index myocardial infarction. Low MCS-12 scores were associated with age below 65 years, low overall self-reported drug therapy compliance, low self-reported compliance with angiotensin-converting enzyme inhibitor and lipid-lowering therapy, no history of coronary artery bypass graft, and no stress test since index myocardial infarction. A multivariate regression model for PCS-12 kept the following variables: greater number of illnesses, history of CHF or TIA, and rehospitalization since index myocardial infarction. The MCS-12 model contained age below 65 years, low overall compliance, and low compliance with lipid-lowering therapy. Further work is necessary to determine noncardiovascular predictors of quality of life and whether interventions for these patients will result in improved quality of life.  相似文献   
65.
66.
67.
BACKGROUND: Although increasing age has been associated with greater risk of mortality for patients undergoing mitral valve replacement, it is less clear whether this elevated risk is related to age-related differences in comorbidity or other clinical characteristics. METHODS: A population of 31,688 patients from The Society of Thoracic Surgeons National Cardiac Database undergoing mitral valve replacement either alone or in combination with coronary artery bypass grafting or tricuspid surgical procedures from 1997 to 2000 was examined to assess age-related variation in clinical features, morbidity, and mortality. Multivariable logistic regression was used to determine the effect of age after adjusting for other known risk factors. A classification tree was used to identify low-risk elderly (> or = 75 years) patients. RESULTS: Operative mortality increased four-fold from 4.1% in patients aged less than 50 years up to 17.0% in patients aged 80 years or more. Similarly, major operative complications (stroke, prolonged ventilation, reoperation for bleeding, renal failure, and sternal infection) also increased with age, rising from 13.5% (age < 50 years) to 35.5% (age > or = 80 years). Multivariable adjustment attenuated the odds of operative mortality, but age remained a significant risk factor. After adjusting for other patient risk factors, age accounted for 13% and 10% of the explainable risk for mortality and morbidity, respectively. Among the elderly, four variables (hemodynamic instability, New York Heart Association class IV, renal failure, and concomitant coronary artery bypass grafting) were identified to distinguish levels of risk, from operative mortality rates exceeding 31% to those with 7.7% mortality. CONCLUSIONS: Operative mortality and morbidity rise with increasing age of patients undergoing mitral valve replacement. Although this excess risk is partially a result of increased comorbid burden and other operative factors, age remains an independent powerful risk factor for operative risk for mitral valve replacement. Understanding the relationship of age with other risk factors for mitral valve replacement can help stratify risk, enabling physicians to identify lower risk patients.  相似文献   
68.
69.
Context  Quality of care of patients with acute myocardial infarction (AMI) has received intense attention. However, it is unknown if a structured initiative for improving care of patients with AMI can be effectively implemented at a wide variety of hospitals. Objective  To measure the effects of a quality improvement project on adherence to evidence-based therapies for patients with AMI. Design and Setting  The Guidelines Applied in Practice (GAP) quality improvement project, which consisted of baseline measurement, implementation of improvement strategies, and remeasurement, in 10 acute-care hospitals in southeast Michigan. Patients  A random sample of Medicare and non-Medicare patients at baseline (July 1998–June 1999; n = 735) and following intervention (September 1–December 15, 2000; n = 914) admitted at the 10 study centers for treatment of confirmed AMI. A random sample of Medicare patients at baseline (January–December 1998; n = 513) and at remeasurement (March–August 2001; n = 388) admitted to 11 hospitals that volunteered, but were not selected, served as a control group. Intervention  The GAP project consisted of a kickoff presentation; creation of customized, guideline-oriented tools designed to facilitate adherence to key quality indicators; identification and assignment of local physician and nurse opinion leaders; grand rounds site visits; and premeasurement and postmeasurement of quality indicators. Main Outcome Measures  Differences in adherence to quality indicators (use of aspirin, -blockers, and angiotensin-converting enzyme [ACE] inhibitors at discharge; time to reperfusion; smoking cessation and diet counseling; and cholesterol assessment and treatment) in ideal patients, compared between baseline and postintervention samples and among Medicare patients in GAP hospitals and the control group. Results  Increases in adherence to key treatments were seen in the administration of aspirin (81% vs 87%; P = .02) and -blockers (65% vs 74%; P = .04) on admission and use of aspirin (84% vs 92%; P = .002) and smoking cessation counseling (53% vs 65%; P = .02) at discharge. For most of the other indicators, nonsignificant but favorable trends toward improvement in adherence to treatment goals were observed. Compared with the control group, Medicare patients in GAP hospitals showed a significant increase in the use of aspirin at discharge (5% vs 10%; P<.001). Use of aspirin on admission, ACE inhibitors at discharge, and documentation of smoking cessation also showed a trend for greater improvement among GAP hospitals compared with control hospitals, although none of these were statistically significant. Evidence of tool use noted during chart review was associated with a very high level of adherence to most quality indicators. Conclusions  Implementation of guideline-based tools for AMI may facilitate quality improvement among a variety of institutions, patients, and caregivers. This initial project provides a foundation for future initiatives aimed at quality improvement.   相似文献   
70.
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