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   2660篇
  免费   200篇
  国内免费   14篇
耳鼻咽喉   23篇
儿科学   142篇
妇产科学   41篇
基础医学   317篇
口腔科学   77篇
临床医学   289篇
内科学   606篇
皮肤病学   66篇
神经病学   120篇
特种医学   292篇
外科学   292篇
综合类   68篇
一般理论   1篇
预防医学   202篇
眼科学   42篇
药学   150篇
中国医学   16篇
肿瘤学   130篇
  2022年   17篇
  2021年   46篇
  2020年   24篇
  2019年   45篇
  2018年   53篇
  2017年   41篇
  2016年   34篇
  2015年   63篇
  2014年   94篇
  2013年   132篇
  2012年   110篇
  2011年   125篇
  2010年   88篇
  2009年   109篇
  2008年   109篇
  2007年   128篇
  2006年   113篇
  2005年   111篇
  2004年   85篇
  2003年   71篇
  2002年   68篇
  2001年   61篇
  2000年   72篇
  1999年   71篇
  1998年   93篇
  1997年   70篇
  1996年   80篇
  1995年   61篇
  1994年   65篇
  1993年   51篇
  1992年   37篇
  1991年   26篇
  1990年   32篇
  1989年   65篇
  1988年   45篇
  1987年   40篇
  1986年   45篇
  1985年   38篇
  1984年   26篇
  1983年   22篇
  1982年   19篇
  1981年   26篇
  1980年   17篇
  1979年   17篇
  1978年   14篇
  1977年   16篇
  1976年   10篇
  1975年   15篇
  1974年   11篇
  1973年   12篇
排序方式: 共有2874条查询结果,搜索用时 31 毫秒
1.
2.
3.
Objectives: To determine interobserver agreement between radiologists for computed tomography (CT) angiography and venography. CT venography of the lower extremities combined with standard CT angiography of the chest may result in an increased overall diagnosis rate of venous thromboembolism (pulmonary embolism or deep venous thrombosis).
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography.  相似文献   
4.
Lymphocytes were cultured from cardiac biopsies following heart transplantation using interleukin-2-conditioned medium. Using the technique of limiting dilution analysis the frequency of donor specific cytotoxic T lymphocytes was measured in cells cultured from biopsies and compared with that in peripheral blood lymphocytes taken at the same time as the biopsy. The graft cell population showed a considerably higher frequency of donor-specific CTL when compared with the PBL. CTL frequencies in the graft cells were always higher against the donor than against third-party cells. These data demonstrate that there was either selective sequestration or selective expansion of donor-reactive T cells in the heart following cardiac transplantation. These results emphasize the need to investigate more closely the events occurring in the heart, and may explain the lack of specificity and sensitivity in immune monitoring (IM) or cytoimmune monitoring (CIM) seen in many centers.  相似文献   
5.
目的 探讨创伤后迟发性脑肿胀的临床特点、发病机制与治疗。方法 回顾性分析1998年1月~2005年6月年收治的17例迟发性脑肿胀患者的临床特点和救治情况。结果 所有颅脑损伤患者采用保守治疗后均有好转,但于伤后5-10d出现恶化,CT复查有脑肿胀,经加强综合脱水等治疗后16例治愈,1例死亡。结论 迟发性脑肿胀好发于对冲性额、颞叶挫裂伤伴明显蛛网膜下腔出血、硬膜下薄层血肿及早期CT有脑肿胀者。其发病机制可能与创伤后的迟发性脑血管痉挛、微循环障碍、静脉回流障碍及甘露醇作用下降等因素有关。此类患者病情隐蔽性强,应加强观察、积极行CT复查,如能早期明确诊断,保守治疗多数效果良好。  相似文献   
6.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  相似文献   
7.
8.
9.
10.
采用间接ELISA检测23名肾移植受者血清巨细胞病毒(CMV)抗体,共检出18名(78%)活动性CMV感染,其中10名(44%)为原发性感染。结果证实CMV-IgE和-IgA具有较好的血清学诊断价值,优于CMV-IgM。  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