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   428篇
  免费   14篇
电工技术   2篇
综合类   4篇
化学工业   42篇
机械仪表   8篇
建筑科学   29篇
矿业工程   1篇
能源动力   10篇
轻工业   19篇
水利工程   1篇
石油天然气   1篇
无线电   33篇
一般工业技术   74篇
冶金工业   133篇
原子能技术   9篇
自动化技术   76篇
  2023年   2篇
  2022年   5篇
  2021年   8篇
  2020年   3篇
  2019年   4篇
  2018年   13篇
  2017年   11篇
  2016年   4篇
  2015年   9篇
  2014年   13篇
  2013年   23篇
  2012年   11篇
  2011年   27篇
  2010年   10篇
  2009年   12篇
  2008年   23篇
  2007年   19篇
  2006年   7篇
  2005年   12篇
  2004年   7篇
  2003年   9篇
  2002年   7篇
  2001年   6篇
  2000年   9篇
  1999年   9篇
  1998年   22篇
  1997年   19篇
  1996年   18篇
  1995年   10篇
  1994年   10篇
  1993年   12篇
  1992年   7篇
  1991年   4篇
  1990年   6篇
  1989年   6篇
  1988年   7篇
  1987年   5篇
  1985年   2篇
  1984年   7篇
  1981年   2篇
  1979年   5篇
  1978年   7篇
  1977年   3篇
  1976年   9篇
  1975年   3篇
  1972年   2篇
  1967年   3篇
  1964年   2篇
  1963年   1篇
  1959年   1篇
排序方式: 共有442条查询结果,搜索用时 11 毫秒
201.
The wafer scale integration of carbon nanotubes (CNT) remains a challenge for electronic and electromechanical applications. We propose a novel CNT integration process relying on the combination of controlled capillary assembly and buried electrode dielectrophoresis (DEP). This process enables us to monitor the precise spatial localization of a high density of CNTs and their alignment in a pre-defined direction. Large arrays of independent and low resistivity (4.4 × 10(-5) Ω m) interconnections were achieved using this hybrid assembly with double-walled carbon nanotubes (DWNT). Finally, arrays of suspended individual CNT carpets are realized and we demonstrate their potential use as functional devices by monitoring their resonance frequencies (ranging between 1.7 and 10.5 MHz) using a Fabry-Perot interferometer.  相似文献   
202.
The goal of this paper is to provide an analysis of the “toolkit” method used in the numerical approximation of the time-dependent Schrödinger equation. The “toolkit” method is based on precomputation of elementary propagators and was seen to be very efficient in the optimal control framework. Our analysis shows that this method provides better results than the second order Strang operator splitting. In addition, we present two improvements of the method in the limit of low and large intensity control fields.  相似文献   
203.
In businesses such as the software industry, which uses knowledge as a resource, activities are knowledge intensive, requiring constant adoption of new technologies and practices. Another feature of this environment is that the industry is particularly susceptible to failure; with this in mind, the objective of this research is to analyze the integration of Knowledge Management techniques into the activity of risk management as it applies to software development projects of micro and small Brazilian incubated technology-based firms. Research methods chosen were the Multiple Case Study. The main risk factor for managers and developers is that scope or goals are often unclear or misinterpreted. For risk management, firms have found that Knowledge Management techniques of conversion “combination” would be the most applicable for use; however, those most commonly used refer to the conversion mode as “internalization.”  相似文献   
204.
This article reviews four decades of deinstitutionalisation policies in three Australian states, New South Wales, Victoria and Queensland. It seeks to understand the factors influencing the slow and haphazard progression of the movement and its more contested outcomes such as the redevelopment of some institutions and their replacement with other congregate or cluster housing models that are at odds with the original visions of community care and normalisation. The article highlights the consistent and effective opposition to deinstitutionalisation from some families of institution residents, and the shifting policy frameworks and ideologies—from ‘normalisation’ to ‘choice’—in which it progressed. In particular, the article highlights the intersections between deinstitutionalisation and urban policy. The article is based on a review of existing scholarly literature, policy documents, inquiry reports and media sources.  相似文献   
205.
The interaction of CO2 with potassium-covered Re(001) has been investigated. This system has been studied by means of work function (Δϕ), optical second harmonic generation (SHG), and temperature-programmed desorption (TPD) measurements. Strong electronic interaction between carbon dioxide and potassium is observed upon adsorption at 90 K. This is indicated by a rapid quenching of the SHG signal of K following postadsorption of CO2, with a quenching cross section of 70 Å2. Work function change measurements are consistent with such interaction, evidenced by an undepolarization effect, namely, further decrease of the work function upon CO2 adsorption, below the minimum obtained by pure potassium. In the presence of potassium, the dissociation probability of 0.5 ML adsorbed carbon dioxide increases from 0.5 on the clean metal surface to 0.85 on 1 ML potassium-covered Re(001), information obtained from TPD measurements following heating to 1250 K. It is concluded that a K–CO2 surface compound is formed upon adsorption at 95 K on the potassium-covered surface.  相似文献   
206.
This paper concerns the construction of the so-called augmented product codes and augmented product lattices. These are obtained by augmenting product codes or product lattices from certain classes thus obtaining higher dimensional codes or lattices from the same class, respectively. Certain properties of the augmented product construction are derived, and specific construction examples are given. In particular, it is shown that the Reed-Muller codes, the Golay code, the Barnes-Wall lattices, as well as the Leech lattice all have various augmented product constructions.  相似文献   
207.
The author examined whether respiratory sinus arrhythmia (RSA) responses to stress predicted resting RSA approximately 3 years later in children and adolescents. A total of 149 children and adolescents (49% girls and women, 44% African Americans) participated in 2 laboratory protocols approximately 3 years apart. RSA reactivity during tasks was consistent within participants across tasks during each session. Resting RSA at Visit 1 explained 17% of the variance in resting RSA at Visit 2 when body mass index, duration between visits, race, gender, and age were controlled for. Visit 1 RSA reactivity explained an additional 5% of the variance in resting RSA at Visit 2. The positive relationship between Visit 1 reactivity and Visit 2 resting levels suggests that larger decreases in RSA during stress predicted lower resting RSA. Conversely, increases in RSA during stress were associated with higher resting RSA an average of 3 years later. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
208.
The purpose of this study was to evaluate the surgical outcomes of the 1.5-mm LactoSorb plating system (Walter Lorenz Surgical, Inc., Jacksonville, FL, U.S.A.) used to stabilize the osteotomized calvarial bone in pediatric patients who have undergone craniofacial surgery. The records of 33 consecutive pediatric patients who underwent craniofacial surgery from January 1997 through December 1997 were reviewed. There were 18 male and 15 female patients, and the age ranged from 4 months to 12 years. Patients were followed-up at 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. For those patients reviewed, the following information is included: age, sex, diagnosis, surgical procedures, number and size of LactoSorb plates and screws used in each patient, operative difficulty of the screws and the heat pack, and postoperative complications, including wound healing, palpability, and infection. The LactoSorb plating system was used to stabilize the osteotomized calvarial bones in 33 patients who were diagnosed with: 1) craniosynostosis, 2) hydrocephalus, 3) fibrous dysplasia, or 4) cranial deformation. Orbital rim advancement and anterior cranial vault reshaping were performed in 17 patients. Posterior cranial vault reshaping, orbital rim advancement, and anterior cranial vault reshaping were performed in eight patients. Posterior cranial vault reshaping only was performed in seven patients. Excision of fibrous dysplasia from temporal bone was performed in one patient. One patient had a postoperative wound infection, and LactoSorb plates were palpable postoperatively in four patients. The LactoSorb plating system provided adequate rigidity for stabilizing the osteotomized calvarial bone during surgery and maintained adequate rigidity after surgery during the bone healing period before absorption. This plating system showed satisfactory results in pediatric craniofacial surgery patients.  相似文献   
209.
Conventional tests of behavioral phenotyping frequently have difficulties differentiating certain genotypes and replicating these differences across laboratories and protocol conditions. This study explores the hypothesis that automated tests can be designed to quantify ethologically relevant behavior patterns that more readily characterize heritable and replicable phenotypes. It used SEE (Strategy for the Exploration of Exploration) to phenotype the locomotor behavior of the C57BL/6 and DBA/2 mouse inbred strains across 3 laboratories. The 2 genotypes differed in 15 different measures of behavior, none of which had a significant genotype-laboratory interaction. Within the same laboratory, most of these differences were replicated in additional experiments despite the test photoperiod phase being changed and saline being injected. Results suggest that well-designed tests may considerably enhance replicability across laboratories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
210.
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