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   309篇
  免费   29篇
  国内免费   1篇
儿科学   4篇
妇产科学   3篇
基础医学   60篇
口腔科学   1篇
临床医学   26篇
内科学   73篇
皮肤病学   21篇
神经病学   29篇
特种医学   29篇
外科学   20篇
综合类   1篇
预防医学   22篇
眼科学   10篇
药学   30篇
肿瘤学   10篇
  2021年   4篇
  2019年   3篇
  2018年   2篇
  2017年   4篇
  2016年   6篇
  2015年   8篇
  2014年   7篇
  2013年   10篇
  2012年   10篇
  2011年   12篇
  2010年   14篇
  2009年   9篇
  2008年   13篇
  2007年   16篇
  2006年   9篇
  2005年   14篇
  2004年   23篇
  2003年   11篇
  2002年   14篇
  2001年   13篇
  2000年   6篇
  1999年   13篇
  1998年   4篇
  1996年   1篇
  1995年   4篇
  1994年   3篇
  1992年   4篇
  1991年   11篇
  1990年   6篇
  1989年   7篇
  1988年   3篇
  1987年   6篇
  1986年   8篇
  1985年   9篇
  1984年   5篇
  1983年   6篇
  1982年   4篇
  1981年   4篇
  1979年   4篇
  1978年   3篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1974年   1篇
  1972年   2篇
  1971年   2篇
  1970年   3篇
  1968年   1篇
  1967年   3篇
  1966年   2篇
排序方式: 共有339条查询结果,搜索用时 31 毫秒
1.
We assessed in 1662 consecutive diabetic patients systolic arm-ankle indexes by a Doppler ultrasonic method. In those patients with indexes greater than or equal to 1.3 directional Doppler sonometry and mercury strain gauge plethysmography were performed. In some instancies electronic oscillography, duplex sonography and vital microscopy were additionally done. In 4.45% of the patients functional findings of a mediasclerosis could be encountered. Location of arterial mediacalcinosis was documented by x-ray examinations. Sensitivity of none invasive methods was merely 100%, specificity ranged from 96% (Dopplersonometry) to 80% (Duplexsonometry). In 18.9% an occlusive arterial disease could additionally be found. Mediasclerosis preferentially was encountered in Type II diabetics of older age. In this group painful distal neuropathy in many instances existed mimicking claudication, retinopathy and nephropathy was as frequent as in other diabetics. Normal or elevated Doppler indexes did not exclude occlusive arterial disease whereas diabetics with mediasclerosis and ulcero-gangreneous lesions or amputations in most of the cases did not have occlusive arterial disease.  相似文献   
2.
Degenerative spondylolisthesis is characterized by the slippage of one vertebral body over the one below, with association of intervertebral disc degeneration and degenerative arthritis of the facet joints, which cause spinal stenosis. The aim of this study was to evaluate the clinical and radiographic results of 22 patients with symptomatic degenerative spondylolisthesis, operated on by decompressive laminectomy and instrumented posterolateral fusion associated with interbody fusion (PLIF). Mean age at surgery was 64 years (range, 57–72). Clinical results were evaluated on a questionnaire at the last follow-up visit concerning postoperative low back and leg pain, restriction of daily life activities, and resumption of sports activity. Lumbar spine radiographs were used to evaluate the status of fixation devices, the reduction of the spondylolisthesis, the lumbar sagittal balance and the presence of spinal fusion. No intraoperative or postoperative complications were encountered. There were no superficial or deep infections, fixation device loosening, or hardware removal. Mean follow-up time was 4 years (range, 3–6 years). Clinical outcome was excellent or good in 19 patients and fair in 3 patients. Preoperatively, mean forward vertebral slipping on neutral lateral radiographs was 5 mm, while postoperatively it decreased to 3 mm. Preoperatively, mean sagittal motion was 3 mm and angular motion was 8°, while postoperatively these values decreased to 1 mm and 1°, respectively. This study demonstrated that spinal decompression followed by transpedicular instrumentation associated with PLIF technique is a valid surgical option for the treatment of degenerative spondylolisthesis with symptomatic spinal stenosis. Clinical outcome, intended as relief of pain and resumption of activity, was improved significantly and fusion rate was high.  相似文献   
3.
4.
Human poly (C) avid serum ribonuclease (RNase) differs in physico-chemical, electrophoretic, and catalytic properties from ribonuclease activity encountered in liver preparations. The first is reported as "secretory type", the latter, because it is undetectable in body fluids, as "nonsecretory type". We determined RNase activity in 11 hepatoma patients. A statistical difference from a normal control of corresponding age was encountered in both age groups investigated (51-60 years, P less than 0.05; 61-70 years, P less than 0.01). The circumstances mentioned above make the tumor itself unlikely to be the source of RNase elevation. Besides a diminished synthesis of RNase inhibitor by hepatoma cells, tumor-derived polyamines could contribute to enhanced RNase activity. The influence of polyamines on RNase activity has already been demonstrated by in vitro experiments. Simultaneous estimation of polyamines and RNase is required to elucidate in vivo circumstances.  相似文献   
5.
Dicationic 2,4-bis(4-amidinophenyl)furans 5-10 and 2, 4-bis(4-amidinophenyl)-3,5-dimethylfurans 14 and 15 have been synthesized. Thermal melting studies revealed high binding affinity of the compounds to poly(dA-dT) and to the duplex oligomer d(CGCGAATTCGCG)2. All of the new compounds were effective against Pneumocystis carinii pneumonia in the immunosuppressed rat model with up to 200-fold increase in activity compared to the control compound pentamidine. No toxicity was noted for 5, 7-10 at the dose of 10 micromol/kg/d; however, the isopropyl analogue 7 showed toxicity comparable to pentamidine at the dosage of 20 micromol/kg/d. Dimethylation of the parent compound on the furan ring resulted in reduced activity and increased toxicity.  相似文献   
6.
Summary The authors, based on their own experience in this field suggest their own therapeutical view which can be described as follows: a much more frequent use of plastic procedures using sliding flaps from the cheek, associated usually with chondromucosal free grafts from the septum, will give not only much better aesthetic results but also a better guarantee against neoplastic recurrence due to the possibility of being able to carry out a much larger ablation.  相似文献   
7.
Hippocampal slices from guinea-pigs were used to examine the long-term potentiation (LTP) of the N-methyl-d-aspartate (NMDA)-mediated excitatory postsynaptic potential (EPSP). Intracellular recordings were performed from CA1 pyramidal neurons in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 - 10 microM) and picrotoxin (50 microM). In these experimental conditions test stimuli applied at low frequency (0.1 Hz) to the Schaffer collateral - commissural pathway evoked a prolonged EPSP (150 - 200 ms). To obtain this CNQX-resistant EPSP, stimulus intensities had to be raised above the level required to evoke an EPSP of comparable amplitude in physiological solution. Tetanic stimulation (two trains of 100 Hz, 1 s every 20 s) led to a potentiation of the CNQX-resistant EPSP, and this potentiated response was abolished with d-(-)-2-amino-5-phosphonovaleric acid (50 microM). The potentiation of the NMDA receptor-mediated EPSP was more pronounced for strong than for weak test stimuli, and was suppressed when test EPSPs were evoked during membrane hyperpolarization. These results suggest that NMDA receptor-mediated responses can undergo LTP, and hence can contribute to the maintenance of LTP.  相似文献   
8.
9.
The effect of Silymarin, a natural flavonoid, on biliary lipid composition, was studied in rats and humans. Bile flow, biliary cholesterol, phospholipid and total bile salt concentrations were measured in 23 control rats and in 27 rats treated with Silibinin, the active component of Silymarin, at the dose of 100 mg/kg body weight i.p. (n = 21) or 50 mg/kg body weight i.p. (n = 6) for 7 days. Biliary cholesterol and phospholipid concentrations were significantly reduced after the higher Silibinin dose (60.9 and 72.9% of the control values), whereas bile flow and biliary total bile salt concentration were unchanged. After the lower Silibinin dose all parameters remained unchanged. Total liver cholesterol content was not affected by Silibinin. On the other hand, in vitro determination of rat liver microsomal 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity showed a significant dose-dependent inhibition by Silibinin (0.5-8 mg/kg). Biliary lipid composition was also assayed in four gallstone and in 15 cholecystectomized patients before and after Silymarin (420 mg per day for 30 days) or placebo administration. In both groups, biliary cholesterol concentrations were reduced after Silymarin treatment and the bile saturation index significantly decreased accordingly. These data suggest that Silibinin-induced reduction of biliary cholesterol concentration both in humans and in rats might be, at least in part, due to a decreased synthesis of liver cholesterol.  相似文献   
10.
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