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   1624篇
  免费   5篇
电工技术   3篇
化学工业   45篇
金属工艺   10篇
机械仪表   14篇
建筑科学   11篇
能源动力   9篇
轻工业   54篇
水利工程   2篇
无线电   30篇
一般工业技术   77篇
冶金工业   1343篇
原子能技术   1篇
自动化技术   30篇
  2022年   2篇
  2021年   3篇
  2020年   2篇
  2019年   4篇
  2017年   2篇
  2016年   4篇
  2015年   2篇
  2014年   2篇
  2013年   15篇
  2012年   12篇
  2011年   16篇
  2010年   15篇
  2009年   10篇
  2008年   16篇
  2007年   9篇
  2006年   16篇
  2005年   9篇
  2003年   11篇
  2002年   8篇
  2001年   12篇
  2000年   6篇
  1999年   41篇
  1998年   436篇
  1997年   217篇
  1996年   136篇
  1995年   95篇
  1994年   73篇
  1993年   85篇
  1992年   14篇
  1991年   19篇
  1990年   18篇
  1989年   29篇
  1988年   18篇
  1987年   27篇
  1986年   22篇
  1985年   16篇
  1984年   7篇
  1983年   10篇
  1982年   11篇
  1981年   11篇
  1980年   21篇
  1979年   6篇
  1978年   5篇
  1977年   40篇
  1976年   67篇
  1975年   6篇
  1974年   3篇
  1972年   5篇
  1971年   4篇
  1970年   2篇
排序方式: 共有1629条查询结果,搜索用时 15 毫秒
1.
With liquefied natural gas becoming increasingly prevalent as a flexible source of energy, the design and optimization of industrial refrigeration cycles becomes even more important. In this article, we propose an integrated surrogate modeling and optimization framework to model and optimize the complex CryoMan Cascade refrigeration cycle. Dimensionality reduction techniques are used to reduce the large number of process decision variables which are subsequently supplied to an array of Gaussian processes, modeling both the process objective as well as feasibility constraints. Through iterative resampling of the rigorous model, this data-driven surrogate is continually refined and subsequently optimized. This approach was not only able to improve on the results of directly optimizing the process flow sheet but also located the set of optimal operating conditions in only 2 h as opposed to the original 3 weeks, facilitating its use in the operational optimization and enhanced process design of large-scale industrial chemical systems.  相似文献   
2.
3.
Thoracic infection by anaerobes are uncommon diseases and often presents difficulty in diagnosis. We report a case of thoracic infection due to Fusobacterium Nucleatum. A 60-year old man presented a lesion infiltrating from the lung to the thoracic wall. Fusobacterium Nucleatum was isolated on pus collected. Treatment by penicillin, metronidazole combined with surgical drainage was highly effective.  相似文献   
4.
The finite-element method (FEM) exhibits a reduced convergence rate when used for the analysis of geometries containing sharp edges where the electromagnetic field is singular. The convergence of the method can be-improved by introducing singular elements that model analytically predicted singular behavior. A number of authors have developed singular elements that are compatible with the scalar FEM. In this paper, we propose a new singular element that is compatible with edge-based vector finite elements and can cope with any order of singularity while preserving the sparsity of the FEM equations. Edge-based singular elements more correctly model singular fields and thus require fewer unknowns, while avoiding the introduction of spurious modes in the numerical solution. Numerical results verify that the convergence of the FEM is significantly improved  相似文献   
5.
6.
7.
8.
9.
The effects of antiepileptic drugs on cognitive function in 48 healthy volunteers were assessed using event-related potentials (ERP) and the Attention Index included in the Wechsler Memory Scale, revised edition (WMS-R). The study was conducted over 1 week, using a double-blind design. Four drugs, carbamazepine (CBZ), phenytoin (PHT), valproate (VPA) and zonisamide (ZNS) were tested. Using an auditory oddball task, ERP measurements were made under two conditions with different tone intensities: Condition 1 used 70 db SPL; and Condition 2 used 30 db SPL. Results showed that CBZ prolonged target N1 and P3 latencies in Condition 1, and reduced frequent N1 amplitude in Condition 2, which suggests that CBZ may cause a change in sensory memory and prolong stimulus evaluation time. It is suggested that under a low stimulus intensity level, the sensory function itself was affected. Phenytoin was found to prolong target N1 latency in Condition 2, which also indicates a change in the sensory memory function. However, VPA did not significantly affect ERP components, except for the shortened frequent N1 latency, which could not be explained due to the limited information. It was found that ZNS augmented P3 amplitude in Condition 2, and reduced scores on the Attention Index. It is suggested that the augmentation of P3 amplitude was caused by the reduction of processing negativity as a result of the detrimental effect of ZNS on subjects' attention. However, the apparent difference between the ERP and behavioral indices suggests that caution should be exercised in assessing the results obtained only from ERP measurements.  相似文献   
10.
The senior authors' initial experience with primary hybrid hip replacement in patients with osteoarthritis was studied to evaluate the efficacy of the procedure. Hybrid total hip arthroplasty (uncemented Harris-Galante acetabular component and cemented Iowa precoated femoral component) was performed in 131 consecutive, nonselected hips in 118 patients with the diagnosis of primary osteoarthritis. Followup was performed at 8 to 9 years after the procedure. The average age at the time of the procedure was 68 years (range, 45-87 years). There were 50 men (55 hips) and 68 women (76 hips). At final followup 19 patients (22 hips) had died. The femoral component had been revised for aseptic loosening in 8 hips (6.1%). One additional hip showed definite radiographic loosening. Hence, the prevalence of radiographic femoral failure was 6.9% (9 hips). No acetabular component had been revised for aseptic loosening and no acetabular component had migrated. The senior author continues to perform hybrid total hip arthroplasty in all patients with primary osteoarthritis. However, design modifications have been made in the femoral component that is used.  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