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   1024篇
  免费   50篇
  国内免费   34篇
耳鼻咽喉   6篇
儿科学   71篇
妇产科学   3篇
基础医学   117篇
口腔科学   33篇
临床医学   129篇
内科学   203篇
皮肤病学   25篇
神经病学   26篇
特种医学   195篇
外科学   71篇
综合类   24篇
预防医学   51篇
眼科学   29篇
药学   45篇
中国医学   1篇
肿瘤学   79篇
  2024年   3篇
  2022年   6篇
  2021年   14篇
  2020年   7篇
  2019年   13篇
  2018年   25篇
  2017年   14篇
  2016年   18篇
  2015年   29篇
  2014年   14篇
  2013年   43篇
  2012年   32篇
  2011年   24篇
  2010年   48篇
  2009年   42篇
  2008年   25篇
  2007年   32篇
  2006年   25篇
  2005年   45篇
  2004年   22篇
  2003年   16篇
  2002年   14篇
  2001年   29篇
  2000年   20篇
  1999年   26篇
  1998年   50篇
  1997年   49篇
  1996年   49篇
  1995年   35篇
  1994年   41篇
  1993年   35篇
  1992年   18篇
  1991年   22篇
  1990年   9篇
  1989年   25篇
  1988年   47篇
  1987年   20篇
  1986年   18篇
  1985年   31篇
  1984年   7篇
  1983年   2篇
  1982年   6篇
  1981年   8篇
  1980年   8篇
  1979年   8篇
  1978年   5篇
  1977年   6篇
  1976年   12篇
  1975年   5篇
  1971年   2篇
排序方式: 共有1108条查询结果,搜索用时 31 毫秒
71.
从平贝母茎叶中分离的平贝啶甙的结构   总被引:2,自引:0,他引:2  
本文报道自平贝母(Fritillaria ussuriensis Maxim)的地上茎叶中分得一种新的甾体生物碱甙,定名为平贝啶甙(pingbeidinoside),mp 242~243.2℃[a]D25+6.9°(c 0.145,MeOH)。经IR,MS,1HNMR和13CNMR谱解析,推定其结构为3β,16α,20-三羟基-Δ5-22,26-缩亚胺胆甾烷-25-O-α-D-葡萄糖甙。  相似文献   
72.
Fifteen allograft transplant recipients acquired lymphoproliferative disorders after immunosuppressive therapy with cyclosporine and steroids. Many of these lymphoproliferative disorders regressed or disappeared completely after reduction of cyclosporine dose. This disease has several aspects that distinguish it from usual posttransplantation lymphomas that occur with regimens that do not contain cyclosporine. The time course from transplantation to onset of lymphoma is relatively short, with an average of approximately 8 months. Organs show a wide spectrum of abnormalities typical of other immunosuppression-associated lymphomas, but there is unique sparing of the central nervous system. The tumor is also unique in that it responds to a decrease in the cyclosporine dose.  相似文献   
73.
The changing pattern of renal tuberculosis   总被引:1,自引:0,他引:1  
The authors present a series of 2,173 patients with renal tuberculosis seen between 1950 and 1979. This is group 1, serving only to show the incidence of renal tuberculosis during the antibiotic era. The fact is that the incidence of renal tuberculosis is going down slightly but constantly in the last years because the resistance of patients is increasing and the virulence of the TB bacillus is decreasing. The second group consists of 128 patients completely examined and the conclusion is that certain forms of very active TB have disappeared; high fever, very active forms of renal TB with deep and limited ulcerations in the kidney do not occur anymore. The third group is formed of 208 patients reviewed in order to demonstrate the residues after long antituberculotic treatment. It has been found that certain residual changes in the parenchyma are minimal but present as the remnants of antibiotic treatment indicating that probably the bilateral forms of renal TB are more common than we supposed before, in full agreement with Cibert's claim.  相似文献   
74.
本文建立了体液中右旋儿茶素的RP-HPLC测定方法。采用C_(18)键合相硅胶为填料的固相提取柱进行样品预处理,右旋儿茶素的提取回收率为79.8%.应用二极管阵列检测器对色谱峰纯度进行鉴定。该法精密度好,方法回收率近100%,日内、日间的变异系数为2.4~5.6%,血浓69.6~1160 ng/ml范围内呈线性关系,r=0.9993。家兔静注右旋儿茶素18mg/kg,其药代动力学过程符合二室模型,分布相半衰期为0.129 h,消除相半衰期为1.19h。  相似文献   
75.
Isthmic spondylolysis of the lumbar spine: MR imaging at 1.5 T   总被引:4,自引:0,他引:4  
The appearance on magnetic resonance (MR) images of the normal pars interarticularis in 13 patients was reviewed and contrasted with that of the pars in eight patients with spondylolysis. The pars defect usually had an intermediate signal intensity with all pulse sequences; however, this intensity was somewhat variable depending on the exact ratio of cartilage, fat, and fluid within each bone defect. The pars defect was best seen with spin-echo 600/20 (repetition time msec/echo time msec) images. In three cases, out-of-phase images showed the spondylolysis best, because of extension of fat to the borders of the defect. The sagittal view allowed one to separate spondylolysis from the joint space of posterior facets since the orientation of the defects is perpendicular to the facets; thus, a common pitfall encountered with cross-sectional axial imaging techniques is avoided. MR imaging poorly delineated bone fragments around the defect, which may produce nerve root impingement, but revealed other numerous complications that occur with spondylolysis, including spondylolisthesis and herniation of the disk above.  相似文献   
76.
Patients with chromosome 22q11 deletion syndrome exhibit significant phenotypic variability. Epidemiologic data suggest a higher incidence in Hispanics, but limited clinical information is available from Latin-American patients. We describe the clinical features of Chilean patients with 22q11 deletion syndrome and compare their findings with those reported in large European, Japanese and US series. Data were obtained from 208 patients from five medical centers. Mean age at diagnosis was 5.2 years, with a median of 2.3 years. Congenital heart defects were present in 59.6%, lower than other large series that averaged 75.8%. Palate abnormalities were present in 79%, higher than previous reports averaging 56%. Patients with congenital heart disease were diagnosed earlier (median 0.3 years of age) than those without heart defects (median 5.6 years) and had greater mortality attributable to the syndrome (9.8% vs 2.4%, respectively). The differences in frequencies of major anomalies may be due to growing awareness of more subtle manifestations of the syndrome, differences in clinical ascertainment or the presence of modifier factors. These observations provide additional data useful for patient counseling and for the proposal of health care guidelines.  相似文献   
77.
78.
79.
80.
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