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   1655篇
  免费   14篇
电工技术   2篇
综合类   1篇
化学工业   26篇
机械仪表   4篇
建筑科学   5篇
能源动力   3篇
轻工业   39篇
水利工程   6篇
无线电   14篇
一般工业技术   9篇
冶金工业   1549篇
自动化技术   11篇
  2021年   4篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   2篇
  2014年   5篇
  2013年   4篇
  2012年   2篇
  2011年   2篇
  2010年   13篇
  2009年   5篇
  2008年   3篇
  2007年   6篇
  2006年   2篇
  2005年   5篇
  2004年   7篇
  2003年   4篇
  2002年   5篇
  2001年   5篇
  2000年   3篇
  1999年   44篇
  1998年   494篇
  1997年   266篇
  1996年   183篇
  1995年   88篇
  1994年   77篇
  1993年   94篇
  1992年   14篇
  1991年   13篇
  1990年   21篇
  1989年   15篇
  1988年   16篇
  1987年   14篇
  1986年   14篇
  1985年   15篇
  1984年   1篇
  1982年   5篇
  1981年   10篇
  1980年   22篇
  1979年   1篇
  1978年   11篇
  1977年   50篇
  1976年   99篇
  1975年   5篇
  1974年   1篇
  1964年   2篇
  1961年   1篇
  1960年   1篇
  1955年   2篇
  1954年   1篇
排序方式: 共有1669条查询结果,搜索用时 15 毫秒
31.
32.
针对当前大型互联网站提升用户体验的需求,本研究创造性地提出基于本体的用户行为分析引擎的思想,它通过上下文感知技术,实时获取用户访问页面时的上下文信息(以下也称为动态行为),基于本体对用户行为建模,建立基于规则的上下文推理算法,对监测到的动态用户行为进行实时推理,及时反馈结果信息给用户。实验表明:本研究理论上独辟蹊径,设计实现上结合了云存储技术,能够一定程度改善用户体验效果。  相似文献   
33.
34.
This paper presents a full reconstruction process of magnetic resonance images. The first step is to bring the acquired data from the frequency domain, using a Fast Fourier Transform algorithm. A Tomographic Image Interpolation is then used to transform a sequence of tomographic slices in an isotropic volume data set, a process also called 3D Reconstruction. This work describes an automatic method whose interpolation stage is based on a previous matching stage using Delaunay Triangulation. The reconstruction approach uses an extrapolation procedure that permits appropriate treatment of the boundaries of the object under analysis.  相似文献   
35.
The five- to six-year all-cause mortality is analysed in 1323 newly diagnosed diabetic patients aged 40 years or over. The median age at diagnosis is lower for males (63.6 years) than for females (67.5 years), but more males (24.7%) than females (20.0%) have died (p = 0.04). This male excess mortality can mainly be attributed to the 60-79-year old males. With increasing diabetes duration both male and female diabetic patients exhibit an increasing excess mortality in comparison with the Danish population. For males this excess mortality becomes statistically significant four years after diagnosis for the 40-59 year-olds and after six years for the 60-79 year-olds. For females and very old males no statistically significant excess mortality is observed, but after two to four years there is a tendency for the survival curve of 40-79-year old females to separate from that of the Danish female population to show an excess mortality. In this population-based study the disadvantageous mortality experience of even newly-diagnosed diabetic patients is clearly demonstrated.  相似文献   
36.
Diagnosis and management may present difficult problems in patients with colovesical fistulas. Symptoms in the urinary tract are most common, and cystoscopy, and cystography are the most valuable diagnostic procedures. It may not always be possible to demonstrate the fistula by diagnostic tests, and a high index of suspicion should be maintained in patients with inflammatory or neoplastic disease of the rectosigmoid area or bladder with recurrent cystitis. Definitive treatment should include resection of the fistula and diseased segment of the intestine. Both one stage and multistage procedures have their place in the treatment of this condition. There are specific criteria for success for a one stage procedure.  相似文献   
37.
Dramatic advances in replantation and microsurgery have somewhat altered the criteria we use in selecting patients to be candidates for upper extremity replantation surgery. We suggest that contraindications for such replantation are: presence of associated life-threatening injuries; serious anesthetic risk; preexisting medical or psychiatric problems; previous injury or disease of the amputated part; warm ischemic time greater than 6-8 hours for extremities or greater than 10-12 hours for digits; and single-digit amputations (except thumb, for grasp). Replantation is feasible when: amputated part is properly preserved; injury type is sharp amputation, mild to moderate crush, or selected avulsion, and amputation is proximal to the DIP joint. Careful preservation of the amputated part, not in dry ice, is mandatory. On an individual basis, the decision to attempt replantation rests on the prediction that the patient may have better function with such surgery than with a prosthesis.  相似文献   
38.
The design of a control package for industrial use on small-scale processes is discussed. A modular system is described, made up of intelligent satellite and peripheral controllers plus various cards to provide communication with the industrial plant itself. The design is intended for operators who have little or no experience of computing. It is based on a language called paracode, an interpretive language structured to provide a number of control sequences which can run independently of each other or in parallel. Two applications of the design—a clean-in-place system and a beer-fermentation controller—are used as illustrations.  相似文献   
39.
This paper discusses two cases of bilateral subcapital fracture of the proximal femur as a complication of myelography with Conray 60. The literature is reviewed.  相似文献   
40.
BACKGROUND: Diagnostic classes (derived from CATEGO) can be correlated with regional brain metabolism in patients with major psychiatric disorders. METHOD: Seventeen patients with schizophrenia, 15 with mania, 10 with depression and 10 healthy Volunteers were examined with positron emission tomography (PET) and 18F-labelled fluorodeoxyglucose, as a marker for glucose metabolism. The number of possible comparisons of regions of interest was reduced by principal-components analysis, and differences in factor scores were determined between diagnostic groups. RESULTS: Four independent factors, representing distributed brain systems, emerged: an anterior-posterior (1), a left-right temporal (2), a temporofrontal (3), and a mediofrontal (4) system, of which (1), (2) and (3) were abnormal in schizophrenia, (1) and (2) in mania, and (1) in depression. CONCLUSIONS: Abnormal patterns of metabolism could be detected, in decreasing order, in schizophrenia, mania and depression. Some of these abnormalities are likely to be due to medication, but others will be associated with structural or functional abnormalities of the frontolimbic system in the diagnostic groups.  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