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   294篇
  免费   21篇
  国内免费   1篇
电工技术   1篇
化学工业   40篇
金属工艺   2篇
机械仪表   3篇
建筑科学   13篇
矿业工程   1篇
能源动力   4篇
轻工业   41篇
水利工程   1篇
无线电   51篇
一般工业技术   55篇
冶金工业   47篇
原子能技术   9篇
自动化技术   48篇
  2024年   1篇
  2023年   4篇
  2022年   3篇
  2021年   2篇
  2020年   5篇
  2019年   4篇
  2018年   6篇
  2017年   15篇
  2016年   4篇
  2015年   8篇
  2014年   12篇
  2013年   17篇
  2012年   17篇
  2011年   18篇
  2010年   14篇
  2009年   14篇
  2008年   18篇
  2007年   9篇
  2006年   13篇
  2005年   12篇
  2004年   11篇
  2003年   15篇
  2002年   9篇
  2001年   7篇
  2000年   4篇
  1999年   4篇
  1998年   15篇
  1997年   7篇
  1996年   7篇
  1995年   5篇
  1994年   4篇
  1993年   6篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1980年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
  1960年   1篇
排序方式: 共有316条查询结果,搜索用时 15 毫秒
11.
The BOAR emulation system is targeted to hardware/software (HW/SW) codevelopment of advanced embedded DSP and telecom systems. The challenge of the BOAR system is efficient customization of programmable hardware, and dedicated partitioning routine to target applications and structures, which allows quite high overall system performance. The system allows multiple configurations for communication between processors and field programmable gate arrays (FPGAs) making the BOAR system an efficient tool for real-time HW/SW coverification. The reprogrammable hardware of the emulation tool is based on four Xilinx 4000-series devices, two Texas TMS320C50 signal processors and one Motorola MC68302 microcontroller. With current devices the BOAR hardware provides approximately 40–70 kgates of logic capacity in DSP applications. The emulation capacity can be expanded by connecting several similar boards in chain. The system has also a versatile internal reprogrammable test environment for test bench development, performance evaluations and design debugging. The logic development environment is based on the Synopsys synthesis tools and an automatic design management software, which performs resource mapping and performance-driven design partitioning between FPGAs. The emulation hardware is currently connected to logic and software development environments via an RS-232C bus. The BOAR emulation system has been found a very efficient platform for real-life prototyping of different types of DSP algorithms and systems, and validating correct functionality of a VHDL macro library.  相似文献   
12.
13.
采用闪急混合工艺使得在最接近流浆箱处向浆料中加入助留剂和施胶化学品等造纸添加剂,并使之迅速和有效地混合。这项多功能混合技术可以做到在同一地点同时将填料、助留剂一起加入到流浆箱中。该工艺操作简单,具有非常短的响应时间,填料留着率更高,纸张性能更优越。由于减少了添加剂在过程中的循环,响应时间非常快速,减少了传统混合过程的水或滤液的量,从而降低了能源消耗,降低了添加剂用量并使工艺过程净化。  相似文献   
14.
The objective of these investigations was to determine the possible effects of the novel selective estrogen receptor modulator, ospemifene, on cytochrome P450 (CYP)-mediated drug metabolism. Ospemifene underwent testing for possible effects on CYP enzyme activity in human liver microsomes and in isolated human hepatocytes. Based on the results obtained in vitro, three Phase 1 crossover pharmacokinetic studies were conducted in healthy postmenopausal women to assess the in vivo effects of ospemifene on CYP-mediated drug metabolism. Ospemifene and its main metabolites 4-hydroxyospemifene and 4′-hydroxyospemifene weakly inhibited a number of CYPs (CYP2B6, CYP2C9, CYP2C19, CYP2C8, and CYP2D6) in vitro. However, only CYP2C9 activity was inhibited by 4-hydroxyospemifene at clinically relevant concentrations. Induction of CYPs by ospemifene in cultured human hepatocytes was 2.4-fold or less. The in vivo studies showed that ospemifene did not have significant effects on the areas under the plasma concentration-time curves of the tested CYP substrates warfarin (CYP2C9), bupropion (CYP2B6) and omeprazole (CYP2C19), demonstrating that pretreatment with ospemifene did not alter their metabolism. Therefore, the risk that ospemifene will affect the pharmacokinetics of drugs that are substrates for CYP enzymes is low.  相似文献   
15.
Department of Intelligent Hydraulics and Automation (IHA) of Tampere University of Technology has been involved in the European Fusion program since 1994 within the ITER reactor maintenance activities. In this paper we discuss the design and development of a six degrees of freedom water hydraulic manipulator with a force feedback for teleoperation tasks. The manipulator is planned to be delivered to Divertor Test Platform 2 (DTP2) during year 2008. The paper also discusses the possibility to improve the fail safe and redundant operation of the manipulator. During the design of the water hydraulic manipulator, special provisions have been made in order to meet the safety requirements such as servo valve block for redundant operation and safety vane brakes for fail safe operation.  相似文献   
16.
Multimodal function optimization, where the aim is to locate more than one solution, has attracted growing interest especially in the evolutionary computing research community. To evaluate experimentally the strengths and weaknesses of multimodal optimization algorithms, it is important to use test functions representing different characteristics and various levels of difficulty. The available selection of multimodal test problems is, however, rather limited and no general framework exists. This paper describes an attempt to construct a software framework which includes a variety of easily tunable test functions. The aim is to provide a general and easily expandable environment for testing different methods of multimodal optimization. Several function families with different characteristics are included. The framework implements new parameterizable function families for generating desired landscapes. Additionally the framework implements a selection of well known test functions from the literature, which can be rotated and stretched. The software module can easily be imported to any optimization algorithm implementation compatible with the C programming language. As an application example, 8 optimization approaches are compared by their ability to locate several global optima over a set of 16 functions with different properties generated by the proposed module. The effects of function regularity, dimensionality and number of local optima on the performance of different algorithms are studied.  相似文献   
17.
Employees continuously observe their work environment and the actions of their fellow workers and superiors, and they use such observations as a basis for the creation of cognitive models associated with safety. These models regulate their actions in the workplace and thus have an influence on safety. This study attempts to define the structure of the safety climate as perceived by workers and the correlations between the safety climate, on the one hand, and the safety practices of the company, the safety level of the work environment and occupational accidents on the other. The variables used in this study were the same as those employed in two previous Finnish safety climate studies carried out in the plywood industry, shipyards, the forestry industry, building construction and stevedoring. The safety climate was measured by means of a questionnaire. Workers from four sawmills, two plywood factories and two parquet plants participated. The total number of participants was 508 in 1990 and 548 in 1993. The variables formed four factors, whose contents and reliabilities closely resembled the results obtained in the earlier studies. These results indicate that the structure of the safety climate among Finnish workers is quite stable. The safety climate correlated both with the safety level of the work environment and with the safety practices of the company, but the correlation between the safety climate and the safety of the work environment was stronger. This result differs from those of the previous studies, in which the safety climate was defined specifically in terms of an individual’s perceptions of the safety practices of the company and of the behavior of other employees. The two safety climate factors that described a company’s attitudes to safety and its safety precautions correlated with the accident rates. The better the safety climate of the company was, the lower was the accident rate. Four companies with an accident rate below the average for the wood-processing industry had a better safety climate than four similar companies with an accident rate above the average.  相似文献   
18.
This paper reports a novel process sequence for fabricating micromechanical devices on silicon-on-insulator (SOI) wafers. Among the merits of the described process are its improved immunity to stiction and elimination of conductor metal endurance problems during sacrificial etching in hydrofluoric acid. With this novel process one can controllably embed vacuum cavities within SOI substrates. Further processing of such cavity wafers enables realization of a wide variety of micromechanical devices based on single crystalline silicon or even integrated read-out circuitry.K. Järvi and T. Häkkinen are gratefully acknowledged for the device fabrication. The Finnish National Technology Agency, Okmetic, VTI Technologies, and Micro Analog Systems participated in funding this work. The ultrasonic devices were fabricated in collaboration with Autotank, Oras, Suunto, Vaisala, and Enermet.  相似文献   
19.
Good reliability of Caco-2 permeability studies requires competent sampling and analytical methods to ensure the comparability of day-to-day experiments. In this work, two n-in-one LC/MS/MS methods based on two different ionization techniques were developed and validated for a group of reference compounds; eight of them are recommended by the Food and Drug Administration (FDA) for the evaluation of oral drug permeability. The performance of a new ionization technique, atmospheric pressure photoionization (APPI), as an interface for quantitative LC/MS analysis was evaluated in comparison to the electrospray ionization (ESI). Generally, the validation parameters, including sensitivity, accuracy, and repeatability, were comparable for the APPI and ESI methods. The main difference was that the linear quantitative range of APPI was 3-4 orders of magnitude (r(2) >/= 0.998) whereas in ESI it was typically 2-3 orders of magnitude (r(2) >/= 0.990). By the APPI and ESI methods, the simultaneous analysis of nine highly heterogeneous compounds was achieved within 5.5-7 min, which leads to significant savings in time and cost of the analyses. The successful validation data indicate the usefulness of both the methods for the rapid and sensitive (LOD values typically 相似文献   
20.
A double approach method for versatile detection of similar objects from the real environment is introduced. By searching both the shape and textural data from the video image, it is possible to solve a generalized location problem without a loss in overall reliability in near–real time. A forest forwarder is used as a proof-of-concept application for the technique.  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