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   4496篇
  免费   335篇
  国内免费   42篇
耳鼻咽喉   35篇
儿科学   161篇
妇产科学   97篇
基础医学   566篇
口腔科学   84篇
临床医学   578篇
内科学   936篇
皮肤病学   41篇
神经病学   473篇
特种医学   273篇
外科学   547篇
综合类   90篇
一般理论   1篇
预防医学   353篇
眼科学   82篇
药学   332篇
中国医学   18篇
肿瘤学   206篇
  2023年   18篇
  2022年   28篇
  2021年   55篇
  2020年   36篇
  2019年   60篇
  2018年   72篇
  2017年   47篇
  2016年   63篇
  2015年   69篇
  2014年   122篇
  2013年   165篇
  2012年   231篇
  2011年   218篇
  2010年   155篇
  2009年   137篇
  2008年   227篇
  2007年   225篇
  2006年   205篇
  2005年   194篇
  2004年   179篇
  2003年   191篇
  2002年   186篇
  2001年   172篇
  2000年   159篇
  1999年   122篇
  1998年   87篇
  1997年   81篇
  1996年   78篇
  1995年   70篇
  1994年   61篇
  1993年   58篇
  1992年   75篇
  1991年   86篇
  1990年   97篇
  1989年   106篇
  1988年   92篇
  1987年   76篇
  1986年   80篇
  1985年   63篇
  1984年   43篇
  1983年   44篇
  1982年   21篇
  1981年   31篇
  1980年   25篇
  1979年   32篇
  1978年   29篇
  1977年   20篇
  1976年   28篇
  1973年   23篇
  1971年   17篇
排序方式: 共有4873条查询结果,搜索用时 15 毫秒
71.
RATIONALE AND OBJECTIVES: Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. MATERIALS AND METHODS: By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. RESULTS: The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. CONCLUSION: The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.  相似文献   
72.
73.
74.
BACKGROUND: Depressive symptoms have been associated with increased cardiac morbidity and mortality rates, but the pathophysiologic mechanism linking depressive symptoms to cardiovascular outcome has yet to be fully understood. Lower heart rate variability has also been associated with increased risk of cardiac events in healthy individuals and in patients with coronary artery disease. Findings regarding a relationship between depressive symptoms and heart rate variability that could explain increased cardiovascular risk have been inconsistent across studies. METHODS: As an ancillary study to the Women's Health Initiative Observational Study, 3372 postmenopausal women aged 50 to 83 years were enrolled for further evaluation using 24-hour ambulatory electrocardiographic monitoring. A shortened version of the Center for Epidemiological Studies Depression Scale and the Diagnostic Interview Schedule were administered. Women with adequate electrocardiographic data and depressive symptom information and without coronary artery disease were analyzed (n = 2627). RESULTS: Two hundred sixty-nine women (10.2%) had depressive symptoms as measured using the 2 instruments. Women with depressive symptoms had a higher mean +/- SD heart rate (77.4 +/- 9.6 vs 75.5 +/- 8.5 beats/min) and lower heart rate variability than women without depressive symptoms. All differences remained significant after adjusting for age (P<.01). CONCLUSIONS: Women with depressive symptoms had significant reductions in heart rate variability and higher heart rates, suggestive of increased sympathetic tone. These findings may contribute to the increased cardiac morbidity and mortality rates associated with depression in other studies.  相似文献   
75.

Background  

Although bacterial cholangitis is frequently mentioned as a cause of secondary sclerosing cholangitis, it appears to be extremely rare, with only one documented case ever reported.  相似文献   
76.
We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.  相似文献   
77.
AIM: Because very little is known about the parenting of drug-abusing men, this study was designed to document ways that drug abuse contributes to compromise of responsible fathering. DESIGN, SETTING, PARTICIPANTS: Generalized linear models and data representing different dimensions of responsible fathering were used to clarify ways that the fathering of 106 men receiving methadone maintenance treatment differed from that of 118 men living in the same community with no history of alcohol or drug abuse. MEASUREMENT: Men who enrolled in the study completed two structured interviews and a battery of five self-report measures selected to document current and historical dimensions of responsible fathering. FINDINGS: When the opioid-dependent fathers were compared to the other fathers, there were significant differences in: (i) economic resources to support family formation; (ii) patterns of pair-bonding; (iii) patterns of procreation; and (iv) parenting behavior. When fathering of the youngest biological child was examined, the opioid-dependent fathers confirmed few differences in historical dimensions of fathering, but they reported significant differences in current dimensions reflecting: (i) constricted personal definitions of the fathering role; (ii) poorer relationships with biological mothers; (iii) less frequent residence with the child; (iv) less frequent provision of financial support; (v) less involvement in positive parenting; (vi) poorer appraisal of self as a father; and (vii) less satisfaction as a father. CONCLUSIONS: The findings highlight ways that drug abuse contributes to compromise of responsible fathering, and they raise questions about ways that the drug abuse treatment system might better address parenting as a treatment issue for men.  相似文献   
78.
79.
Plasma values of C reactive protein, alpha 1 proteinase inhibitor, alpha 2 macroglobulin, and complexed alpha 2 macroglobulin have been determined in serial samples from 27 patients with acute pancreatitis. Complexed alpha 2 macroglobulin was measured by a novel enzyme linked immunosorbent assay with a monoclonal antibody specific for the complexed form. Patients with severe illness had lower concentrations of total alpha 2 macroglobulin and higher concentrations of complexed alpha 2 macroglobulin than those with mild illness, and in the majority of severe attacks the abnormal amounts of complexed alpha 2 macroglobulin were present throughout the eight days of the study. The proportion of total alpha 2 macroglobulin in the uncomplexed form, however, was generally greater than 90%, and in 26% of the mild cases completely normal concentrations of uncomplexed alpha 2 macroglobulin (greater than 99% of total) were found throughout the eight days of the study. This suggests that exhaustion of alpha 2 macroglobulin in plasma is unlikely to be a major factor in the pathogenesis of acute pancreatitis.  相似文献   
80.
This study examined the relationships between lifetime years of cocaine, alcohol, and marijuana use prior to entry into residential treatment for primary cocaine dependence and (a) intake depression levels, and (b) levels of cocaine use in the six months after completing treatment. Years of education, age, and lifetime years of cocaine and alcohol use contributed significantly to predicting depression levels. Lifetime years of alcohol use alone predicted cocaine use during the six months post-treatment.  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