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   148061篇
  免费   32079篇
  国内免费   2388篇
耳鼻咽喉   5153篇
儿科学   5329篇
妇产科学   2365篇
基础医学   2882篇
口腔科学   1462篇
临床医学   26491篇
内科学   46848篇
皮肤病学   7414篇
神经病学   14622篇
特种医学   6294篇
外科学   40701篇
综合类   227篇
现状与发展   72篇
预防医学   6922篇
眼科学   3312篇
药学   840篇
中国医学   6篇
肿瘤学   11588篇
  2024年   684篇
  2023年   4776篇
  2022年   1170篇
  2021年   3043篇
  2020年   6003篇
  2019年   2120篇
  2018年   7335篇
  2017年   7300篇
  2016年   8369篇
  2015年   8357篇
  2014年   15421篇
  2013年   15524篇
  2012年   5320篇
  2011年   5322篇
  2010年   10264篇
  2009年   14162篇
  2008年   5654篇
  2007年   3877篇
  2006年   6351篇
  2005年   3640篇
  2004年   2916篇
  2003年   1895篇
  2002年   1989篇
  2001年   3770篇
  2000年   2983篇
  1999年   3187篇
  1998年   3627篇
  1997年   3448篇
  1996年   3350篇
  1995年   3200篇
  1994年   1934篇
  1993年   1557篇
  1992年   1367篇
  1991年   1400篇
  1990年   1052篇
  1989年   1172篇
  1988年   1011篇
  1987年   846篇
  1986年   880篇
  1985年   710篇
  1984年   543篇
  1983年   517篇
  1982年   511篇
  1981年   398篇
  1980年   358篇
  1979年   306篇
  1978年   328篇
  1977年   396篇
  1975年   277篇
  1972年   302篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
95.
BACKGROUND AND PURPOSE: Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. METHODS: To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH < or =2 cm was estimated, using the number of dotHSs and risk factors for stroke. RESULTS: The number of dotHSs associated with the diameter < or =2 cm was 9.2 +/- 11.5, significantly larger than that with the diameter > or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). CONCLUSION: Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH.  相似文献   
96.
97.
Lymphocyte-predominant Hodgkin’s lymphoma (LPHL) differs in histologic and clinical presentation from classical Hodgkin’s lymphoma (cHL). Treatment of LPHL patients using standard Hodgkin’s lymphoma protocols leads to complete remission in more than 95% of patients. Survival and freedom from treatment failure are substantially worse in advanced-stage patients than for early-stage patients. Thus, patients in advanced stages and those in early stages with unfavorable risk factors should be treated similar to those with cHL. In contrast, patients with early-stage LPHL without risk factors might be sufficiently treated with reduced-intensity programs having less severe adverse effects. As a result, treatment of early LPHL is rather heterogeneous, including radiotherapy using extended-fleld technique, involved-fleld radiotherapy (IF-RT), combined-modality treatment, and, more recently, monoclonal antibodies. Watch-and-wait strategy plays an important role in pediatric oncology, to avoid adverse effects associated with therapy. IF-RT seems to be emerging as a treatment of choice for patients with stage IA LPHL; most larger study groups, such as the German Hodgkin Study Group and the European Organisation for Research and Treatment of Cancer, have adopted IF-RT as the treatment of choice for these patients.  相似文献   
98.
99.
Anxiety disorders and anxiety symptoms are highly prevalent in the general population and more so in the medically ill. They have a number of negative consequences for these patients and may worsen the outcome of the medical illness and increase health care utilization. In the evaluation of these patients, it is of paramount importance to identify the etiology of the anxiety and, in particular, to differentiate primary from secondary anxiety. Management includes medications (especially benzodiazepines and selective serotonin reuptake inhibitors) and psychotherapy (particularly cognitive-behavioral therapy).  相似文献   
100.
OBJECTIVE: The application of intensity thresholds for embolus detection with transcranial Doppler (TCD) can exclude from analysis an unrecognized proportion of high-intensity transient signals (HITS))whose intensities are below the threshold. The lack of consistent threshold criteria between clinical trials may explain part of the discrepancy in the reported HITS counts. We investigated the effect of choosing different thresholds on the sensitivity and specificity of detecting HITS during cardiopulmonary bypass (CPB). METHODS: Two observers independently analyzed TCD recordings from 8 patients under CPB. Doppler signals were classified as true HITS, equivocal HITS, artifacts, and Doppler speckles according to preestablished criteria. The relative intensity of Doppler signals was measured by two different methods (TCD software vs manual). Receiver Operating Characteristic curves determined the optimal threshold for each of the two intensity methods. RESULTS: Reviewers achieved agreement in 96% of 2190 Doppler signals (kappa = 0.90). Relative intensities calculated with the TCD-software method were 3 dB (95% CI: 3.0-3.4) higher than the manual method. The optimal threshold was found at 10 dB (sensitivity: 99%; specificity: 90.8%) with the software method and at 7 dB with the manual method (sensitivity: 96%; specificity: 83%). The use of an intensity threshold 2 dB higher than the optimal increased the rejection of true HITS by 8% and 14%, respectively. CONCLUSIONS: Using intensity thresholds higher than the optimal for embolus detection decreases HITS counts. Choosing a threshold depends on the type of method used for measuring the signal intensity. Uniform threshold criteria and comparative studies between different Doppler devices are necessary for making clinical trials more comparable.  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