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   1863篇
  免费   134篇
  国内免费   30篇
耳鼻咽喉   10篇
儿科学   44篇
妇产科学   23篇
基础医学   204篇
口腔科学   49篇
临床医学   201篇
内科学   322篇
皮肤病学   16篇
神经病学   222篇
特种医学   150篇
外科学   220篇
综合类   36篇
一般理论   1篇
预防医学   229篇
眼科学   9篇
药学   130篇
中国医学   21篇
肿瘤学   140篇
  2021年   14篇
  2020年   16篇
  2019年   27篇
  2018年   27篇
  2017年   22篇
  2016年   22篇
  2015年   26篇
  2014年   36篇
  2013年   74篇
  2012年   85篇
  2011年   79篇
  2010年   54篇
  2009年   50篇
  2008年   77篇
  2007年   86篇
  2006年   83篇
  2005年   85篇
  2004年   66篇
  2003年   64篇
  2002年   56篇
  2001年   53篇
  2000年   62篇
  1999年   49篇
  1998年   34篇
  1997年   38篇
  1996年   36篇
  1995年   21篇
  1994年   32篇
  1993年   36篇
  1992年   43篇
  1991年   32篇
  1990年   28篇
  1989年   64篇
  1988年   32篇
  1987年   49篇
  1986年   35篇
  1985年   41篇
  1984年   37篇
  1983年   20篇
  1982年   20篇
  1981年   24篇
  1980年   13篇
  1979年   20篇
  1978年   17篇
  1977年   15篇
  1976年   16篇
  1975年   21篇
  1974年   14篇
  1973年   10篇
  1968年   8篇
排序方式: 共有2027条查询结果,搜索用时 15 毫秒
1.
2.
3.
Fifty-one patients with deep-seated soft tissue sarcoma of the extremities and trunk wall were examined with contrast-enhanced CT for presence of nonenhanced tumor areas (CT necrosis). After a median follow-up time of 3 years, 19 of the 41 patients with CT necrosis had developed metastases, compared to none of the 10 patients who had tumors without CT necrosis. Tumors with CT necrosis were larger than tumors without, but in tumors of similar size, absence of CT necrosis was a favorable prognostic sign.  相似文献   
4.
A technique for transperineal high-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI-guided transperineal prostate biopsies were obtained followed by placement of 14-15 hollow transperineal catheters for HDR brachytherapy. Mean needle-placement accuracy was 2.1 mm, 95% of needle-placement errors were less than 4.0 mm, and the maximum needle-placement error was 4.4 mm. In addition to guiding the placement of biopsy needles and brachytherapy catheters, MR images were also used for brachytherapy treatment planning and optimization. Because 1.5 T MR images are directly acquired during the interventional procedure, dependence on deformable registration is reduced and online image quality is maximized.  相似文献   
5.
6.
以18-甲基-17β-羟基-17α-乙炔基-雌甾-4-烯-3-酮(18-甲基炔诺酮),17β-羟基-17α-乙缺基-雌甾-4-烯-3-酮(炔诺酮),17β-羟基-17α-乙炔基-雄甾-4-烯-3-酮(妊娠素)和17a-羟基孕甾-4-烯-3,20二酮(17α-羟基黄体酮)为原料,经NaBH,还原、脱水、双键转位和酯化等反应合成一系列3,5-甾二烯化合物,用1HNMR和MS证明了它们的结构。动物筛选结果表明,17β-丙酰氧基-17α-乙炔基-雌甾-3,5-二烯(IVb2有明显的抗早孕活性。中断早期妊娠的作用似与其雌激素活性有关。  相似文献   
7.
Bile duct calculi in patients with primary sclerosing cholangitis   总被引:1,自引:0,他引:1  
  相似文献   
8.
9.
We analysed 256 patients with primary soft-tissue sarcoma of the extremities diagnosed between 1970 and 1990 to see if tumour-related and host-related prognostic factors influenced both the selection of operation and the margin of clearance obtained at surgery. Amputation was more often performed in young patients, in those with distal tumours, and in those with deep-seated tumours. Inadequate surgical margins (those with a high risk of local recurrence) were more common in patients with deep-seated and large tumours than in patients with superficial and small tumours. These features of the tumour and the host, which have been shown to be prognostic for survival, also influenced the choice and performance of surgical procedures.  相似文献   
10.
Fractures after Stroke   总被引:6,自引:0,他引:6  
Fractures are a serious complication after stroke. Among patients with femoral neck fractures, a large subgroup have had a previous stroke. This study aimed to investigate the incidence of fractures after stroke. Included in the study were 1139 patients consecutively admitted for acute stroke. Fractures occurring from stroke onset until the end of the study or death were registered retrospectively. Hip fracture incidence was compared with corresponding rates from the general population. Patients were followed up for a total of 4132 patient-years (median 2.9 years). There were 154 fractures in 120 patients and median time between the onset of stroke and the first fracture was 24 months. Women had significantly more fractures than men (χ2 = 15.6; p < 0.001). In patients with paresis most of the fractures affected the paretic side (χ2 = 22.5; p < 0.001) and 84% of the fractures were cause by falls. Hip fracture was the most frequent fracture and the incidence was 2–4 times higher in stroke patients compared with the reference population. Fractures are thus a common complication after stroke. They are usually caused by falls and affect the paretic side. It is necessary to focus on the prevention of post-stroke fractures, including the prevention of both falls and osteoporosis.  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