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   6473篇
  免费   391篇
  国内免费   47篇
耳鼻咽喉   30篇
儿科学   156篇
妇产科学   184篇
基础医学   1049篇
口腔科学   79篇
临床医学   529篇
内科学   1709篇
皮肤病学   287篇
神经病学   608篇
特种医学   160篇
外科学   496篇
综合类   11篇
一般理论   3篇
预防医学   385篇
眼科学   36篇
药学   422篇
中国医学   26篇
肿瘤学   741篇
  2024年   6篇
  2023年   59篇
  2022年   152篇
  2021年   215篇
  2020年   121篇
  2019年   182篇
  2018年   208篇
  2017年   138篇
  2016年   159篇
  2015年   216篇
  2014年   269篇
  2013年   329篇
  2012年   498篇
  2011年   545篇
  2010年   298篇
  2009年   248篇
  2008年   411篇
  2007年   403篇
  2006年   445篇
  2005年   393篇
  2004年   373篇
  2003年   317篇
  2002年   304篇
  2001年   47篇
  2000年   34篇
  1999年   46篇
  1998年   57篇
  1997年   61篇
  1996年   53篇
  1995年   48篇
  1994年   33篇
  1993年   31篇
  1992年   20篇
  1991年   21篇
  1990年   19篇
  1989年   21篇
  1988年   20篇
  1987年   18篇
  1986年   14篇
  1985年   7篇
  1984年   12篇
  1983年   4篇
  1981年   7篇
  1980年   4篇
  1979年   5篇
  1977年   8篇
  1974年   5篇
  1970年   6篇
  1967年   5篇
  1932年   2篇
排序方式: 共有6911条查询结果,搜索用时 15 毫秒
991.
992.
The Frog Embryo Teratogenesis Assay Xenopus (FETAX), is a screening assay using embryos at gastrula stage of the anuran Xenopus laevis to identify substances that may pose a developmental hazard in humans. The FETAX assay evaluates three parameters, i.e. mortality, delayed growth and embryo malformation. In the present investigation, the FETAX protocol was applied to the marine toxin okadaic acid (OA) and the experiments show that OA affects the above parameters in a dose-correlated manner. The morpho-functional modifications induced in embryo organs by OA were also studied. The nervous system, tail skeletal musculature, intestine and kidney appeared particularly damaged, with the former being the most sensitive. On the whole, various advantages emerge from using the FETAX assay: different parameters can be tested simultaneously, the indication of the presence of a potentially dangerous substance is rapid and the assay is a valid alternative to mammalian systems.  相似文献   
993.
BACKGROUND: The pedicled TRAM (pTRAM) flap is one of the best options for autologous breast reconstruction, but vascular complications reported in the standard versions are about 30%. To reduce complication rate, especially in high-risk patients, surgical delay has been suggested.Individual precise preoperative location and evaluation of perforating vessels and of variations of the diameter of the deep superior epigastric artery (DSEA) are highly desirable for improving surgical strategy. Previous reports using color duplex scanning, although generally confirming the validity of the delay maneuver, have showed several pitfalls. The aim of this report was to demonstrate the usefulness of multidetector computed tomography angiography (MDCTA) for preoperative planning in patients undergoing pTRAM flap breast reconstruction after selective vascular delay. METHODS: Three patients were considered for breast reconstruction with the pTRAM flap. An MDCTA was performed before and after selective delay to locate the muscle perforators and to show increase in DSEA diameter. Axial images, multiplanar reconstruction, and 3D volume images were analyzed. RESULTS: Accurate identification of the main perforators was achieved. Location, course, and anatomic variations of DSEA were reported. The average increase in diameter of the DSEA was 29.3%. CONCLUSION: Preoperative planning of pTRAM flap with MDCTA allows surgeons to visualize and locate the dominant perforators and to select the best DSEA. Consequently, the choice between the homolateral or contralateral rectus muscle is facilitated. The high sensitivity and specificity and the ease of interpreting data have made MDCTA a highly promising diagnostic tool for planning a pTRAM flap.  相似文献   
994.
OBJECTIVES: This prospective, multicentre, randomised study compared the safety and success rate of tension-free vaginal tape (TVT) and transobturator tape (TOT) in treatment of female stress urinary incontinence. METHODS: Of 148 women, 73 were randomised to TVT and 75 to TOT. Preoperative workups included case history, clinical examination, Urogenital Distress Inventory and Impact Incontinence Quality of life questionnaires, 1-h pad test, pelvic ultrasound, and urodynamics. Intra- and postoperative complications were the primary end point; subjective and objective changes in SUI, and postoperative voiding dysfunctions were secondary end points. Patients were classified into two main categories: dry (no leakage during clinical and/or stress test and/or reported by patients) versus wet. Patients who referred being wet were separated into "improved" or "failure" on subjective analysis. Other outcome variables were quality of life questionnaires and VAS scale. Clinical checkups were conducted at 3, 6, 12 mo, and then annually. RESULTS: Both techniques are safe and no significant differences emerged in intra- and postoperative complications. At a mean follow-up of 31 mo, the overall objective cure (dry) was 71.4% for TVT and 77.3% for TOT (p=ns). When one considered "dry" plus "wet but improved," these values increased to 90% and 90.6%, respectively (p=ns). Median satisfaction rate was 9 (range: 1-10) for both procedures. Postoperative storage symptoms are a controversial issue; they persisted in 44% of patients in TVT group versus 24% in TOT group (p<0.053). CONCLUSIONS: TOT appears as safe and effective as TVT in surgery for female SUI, with minimal complications at mean follow-up of 31 mo.  相似文献   
995.
Although more advanced techniques such as intensity-modulated radiotherapy are rapidly spreading, 3D conformal radiotherapy (3D-CRT) remains the standard of treatment for many diseases. The authors outline essential indications to guarantee the quality of 3D-CRT treatments. Criteria for clinical indications and potential clinical advantages and disadvantages of 3D-CRT technology are presented. After briefly listing human and technological resources requirements, procedures for 3D-CRT and physical aspects peculiar to 3D-CRT are described. Medical physics support activities are also considered, including suggestions concerning quality control protocols. Difficulties in the application of correct quality procedures, particularly related to human and technological resources, procedures for patient positioning, imaging, contouring, treatment planning, in vivo dosimetry, set-up verification, follow-up, dose delivery are then discussed.  相似文献   
996.

Background  

In recent years, rotavirus genotyping by RT-PCR has provided valuable information about the diversity of rotaviruses (RV) circulating throughout the world.  相似文献   
997.
998.
Widespread plaque inflammation has been demonstrated in acute coronary syndromes (ACS). We evaluated signs of plaque inflammation in carotid arteries of patients with ACS by contrast-enhanced magnetic resonance imaging (MRI). Carotid MRI was performed in 13 patients with ACS and in 9 controls having at least 1 carotid plaque with a stenosis > or =40%. MRI criteria of plaque inflammation were: increased T2 signal >50% of the plaque areas (tissue oedema) and/or enhancement after gadolinium injection (neo-vascularization). MRI signs of inflammation were found in 95% and in 33% of patients with ACS and controls, respectively (p<0.001). Carotid artery MRI may serve as a window to the entire cardiovascular system, to identify "vulnerable" patients.  相似文献   
999.
1000.
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