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   2487篇
  免费   251篇
  国内免费   17篇
耳鼻咽喉   16篇
儿科学   53篇
妇产科学   43篇
基础医学   381篇
口腔科学   19篇
临床医学   395篇
内科学   611篇
皮肤病学   20篇
神经病学   263篇
特种医学   49篇
外科学   268篇
综合类   17篇
一般理论   3篇
预防医学   290篇
眼科学   15篇
药学   145篇
中国医学   7篇
肿瘤学   160篇
  2023年   17篇
  2022年   40篇
  2021年   89篇
  2020年   45篇
  2019年   70篇
  2018年   60篇
  2017年   66篇
  2016年   67篇
  2015年   65篇
  2014年   94篇
  2013年   147篇
  2012年   247篇
  2011年   219篇
  2010年   102篇
  2009年   94篇
  2008年   149篇
  2007年   143篇
  2006年   139篇
  2005年   127篇
  2004年   107篇
  2003年   104篇
  2002年   83篇
  2001年   37篇
  2000年   49篇
  1999年   45篇
  1998年   17篇
  1997年   13篇
  1996年   10篇
  1995年   5篇
  1994年   11篇
  1993年   8篇
  1992年   24篇
  1991年   29篇
  1990年   24篇
  1989年   24篇
  1988年   26篇
  1987年   20篇
  1986年   13篇
  1985年   7篇
  1984年   15篇
  1983年   11篇
  1982年   10篇
  1981年   18篇
  1980年   10篇
  1979年   11篇
  1977年   5篇
  1975年   5篇
  1971年   7篇
  1969年   4篇
  1967年   4篇
排序方式: 共有2755条查询结果,搜索用时 31 毫秒
1.
We present the case of 7‐year‐old African American girl with loose anagen syndrome. Although this is a common cause of hair loss in Caucasian children, and there have been reports of cases occurring in dark‐skinned children of North African and Middle Eastern descent, to our knowledge there have been no cases reported in black children of sub‐Saharan African ancestry. We present this case to broaden the differential diagnosis of hair loss in African Americans.  相似文献   
2.
Previous research has demonstrated heterogeneity of the simple phobia diagnostic category. As a further test of the notion of heterogeneity of the DSM-III-R simple phobia diagnostic category, mode of onset was examined in a sample of simple phobic outpatients. Patients were separated into one of four subtypes: animal or insect, blood and injury, situational, and choking-vomit phobias. Careful study yielded five distinct mode-of-onset categories. Two researchers independently determined the mode of onset for the patients studied: direct trauma, spontaneous, vicarious learning, gradual, and lifelong. Significant mode of onset differences were observed across groups. Situational phobics reported a preponderance of spontaneous onsets as compared to the other groups studied. These results offer further evidence of the heterogeneity of the simple phobia diagnostic category and also support the contention that situational simple phobias are closely related to agoraphobia.  相似文献   
3.
OBJECTIVES: The purpose of this study was to determine quality of life (QOL) and exercise performance (EP) in patients with persistent atrial fibrillation (AF) converted to sinus rhythm (SR) compared with those remaining in or reverting to AF. BACKGROUND: Restoration of SR in patients with AF improving QOL and EP remains controversial. METHODS: Patients with persistent AF were randomized double-blind to amiodarone, sotalol, or placebo. Those not achieving SR at day 28 were cardioverted and classified into SR or AF groups at 8 weeks (n = 624) and 1 year (n = 556). The QOL (SF-36), symptom checklist (SCL), specific activity scale (SAS), AF severity scale (AFSS), and EP were assessed. RESULTS: Favorable changes were seen in SR patients at 8 weeks in physical functioning (p < 0.001), physical role limitations (p = 0.03), general health (p = 0.002), and vitality (p < 0.001), and at 1 year in general health (p = 0.007) and social functioning (p = 0.02). Changes in the scores for SCL severity (p = 0.01), functional capacity (p = 0.003), and AFSS symptom burden (p < 0.001) at 8 weeks and in SCL severity (p < 0.01) and AF symptom burden (p < 0.001) at 1 year showed significant improvements in SR versus AF. Symptomatic patients were more likely to have improvement. The EP in SR versus AF was greater from baseline to 8 weeks (p = 0.01) and to 1 year (p = 0.02). The EP correlated with physical functioning and functional capacity except in the AF group at 1 year. CONCLUSIONS: In patients with persistent AF, restoration and maintenance of SR was associated with improvements in QOL measures and EP. There was a strong correlation between QOL measures and EP.  相似文献   
4.
INTRODUCTION: Farming is a dangerous occupation and results in injuries not only to farm workers, but also to families living on farms. Children raised on a farm are at particular risk because the farm is a place where they live, play, and work. Farming is the main Amish occupation, and because Amish farming techniques differ from those used on other us farms, it is important that health care providers recognize the causes of injuries that may occur on Amish farms. However, little is documented about farm-related injuries in Amish children, so we decided to document the incidence and nature of these injuries in Pennsylvania. METHODS: This study was done by reviewing the die botschaft, a weekly newspaper written by the Amish. All references to farm-related injuries among children in Pennsylvania were recorded. RESULTS: During a 5-month period, a total of 89 injuries, including 5 fatalities, were found: male children sustained 64 injuries, and female children sustained 25 injuries. Falls were the most commonly reported mechanism of injury, followed by incidents involving livestock. Both types of events most often resulted in an orthopedic injury. DISCUSSION: Injury to children in the Amish community is a significant problem that needs to be addressed and evaluated by the Amish themselves and in coordination with other health care providers, including emergency nurses. With the information obtained in this study, injury prevention strategies tailored to the Amish way of farming could be developed and implemented.  相似文献   
5.
6.
Educational technologies have changed the paradigm of the teacher-student relationship in nursing education. Nursing students expect to use and to learn from cutting edge technology during their academic careers. Varied technology, from specified software programs (Tegrity and Blackboard) to the use of the Internet as a research medium, can enhance student learning. The authors provide an overview of current cutting edge technologies in nursing classroom instruction and its impact on future nursing practice.  相似文献   
7.
Current models hold that CD4+ depletion occurs as a result of direct and indirect effects of HIV, which both kill peripheral CD4+ cells and prevent adequate regeneration. Although age-associated involution diminishes thymic reserve and HIV is clearly thymotoxic, clinical trials have nonetheless shown that large proportions of patients who sustain adequate control of viral replication with highly active antiretroviral therapy (HAART) will demonstrate some evidence for thymic-dependent immune reconstitution, which is associated with improved immune competence. Furthermore, patients with insufficient or absent immune reconstitution following HAART generally lack evidence for thymopoiesis. Current studies are focused on improving our understanding of the causes for thymic failure in HIV infection. Recent work has demonstrated that some HIV strains, especially those that are CXCR4 trophic, are more thymotoxic and may contribute to irreversible thymic damage in this population.  相似文献   
8.
Current models hold that CD4+ depletion occurs as a result of direct and indirect effects of HIV, which both kill peripheral CD4+ cells and prevent adequate regeneration. Although age-associated involution diminishes thymic reserve and HIV is clearly thymotoxic, clinical trials have nonetheless shown that large proportions of patients who sustain adequate control of viral replication with highly active antiretroviral therapy (HAART) will demonstrate some evidence for thymic-dependent immune reconstitution, which is associated with improved immune competence. Furthermore, patients with insufficient or absent immune reconstitution following HAART generally lack evidence for thymopoiesis. Current studies are focused on improving our understanding of the causes for thymic failure in HIV infection. Recent work has demonstrated that some HIV strains, especially those that are CXCR4 trophic, are more thymotoxic and may contribute to irreversible thymic damage in this population.  相似文献   
9.
10.
Continuous renal replacement therapy (CRRT), such as continuous venovenous hemofiltration, has theoretical advantages over intermittent hemodialysis (IHD) that are related to cardiorespiratory stability, metabolic control, and fluid balance allowing nutritional supplementation. However, retrospective and controlled studies fail to show these advantages because of comorbidity associated with triage to CRRT. To compare outcomes using IHD versus CRRT, we applied published risk stratification models (Cleveland Clinic Foundation, Lohr index, and APACHE II) to the 349 patients with acute renal failure requiring renal replacement therapy at University of Michigan over the 2 year period including 1995 and 1996. The Cleveland Clinic Foundation model best predicted overall mortality, but our CRRT patients had excess, unpredicted mortality that was particularly prominent in the lower risk categories. The Lohr clinical score predicted mortality less accurately but also was associated with higher, unpredicted mortality at lower risk scores among the CRRT patients. APACHE II scores did not predict mortality very well among IHD, CRRT, or the combined group of patients. We conclude that the need for CRRT itself predicts mortality over and above that included in published risk models. Either CRRT is associated with some unidentified morbidity (e.g., treatment associated infection) or, more likely, triage to CRRT is associated with as yet unspecified comorbidity not detected in existing risk stratification schemes. It will be important to address these issues in any future studies evaluating outcome or comparing renal replacement therapy modalities among patients with severe acute renal failure.  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