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   511篇
  免费   27篇
  国内免费   1篇
电工技术   6篇
化学工业   150篇
金属工艺   10篇
机械仪表   6篇
建筑科学   19篇
能源动力   19篇
轻工业   83篇
水利工程   2篇
无线电   30篇
一般工业技术   101篇
冶金工业   52篇
原子能技术   2篇
自动化技术   59篇
  2024年   4篇
  2023年   8篇
  2022年   15篇
  2021年   16篇
  2020年   12篇
  2019年   10篇
  2018年   19篇
  2017年   21篇
  2016年   10篇
  2015年   15篇
  2014年   15篇
  2013年   35篇
  2012年   27篇
  2011年   38篇
  2010年   25篇
  2009年   28篇
  2008年   19篇
  2007年   36篇
  2006年   28篇
  2005年   14篇
  2004年   12篇
  2003年   6篇
  2002年   9篇
  2001年   4篇
  2000年   6篇
  1999年   3篇
  1998年   21篇
  1997年   9篇
  1996年   8篇
  1995年   8篇
  1994年   7篇
  1993年   5篇
  1992年   2篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   5篇
  1987年   2篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1976年   3篇
  1975年   2篇
  1974年   1篇
  1971年   2篇
  1960年   1篇
排序方式: 共有539条查询结果,搜索用时 0 毫秒
51.
Single-phase sintered ceramic materials (ZrO2)1?x {(Y2O3) y (RE2O3)1-y x }x (RE=Nd, Ce, Dy, Er), were synthesized and electrical conductivity and transport number measurements were made as a function of temperature between 500 and 1200° C. The activation energies of conduction were determined, and it was found that the charge carriers in these solid solutions are oxygen ions. The fabricated electrolyte discs were used in cells of the type \(P_{O_2 }\) , Pt/zirconia solid solution/ \(P_{\mathop O\limits^{'} _2 }\) , platinum where \(P_{O_2 }\) =air (0.21 atm) and \(P_{\mathop O\limits^{'} _2 }\) =1 atm or argon-O2 mixtures. Below 700° C, the e.m.f. deviated from the theoretical values for completely ionic conduction; good agreement was observed above this temperature.  相似文献   
52.
In this letter, we propose a voltage-source inverter control working in the open loop of an induction motor measuring the stator current and using an artificial neural network. This technique has the mission to estimate the speed and torque of the rotor without using sensors. With this, a simple and cheap method of control is obtained, with as much precision and robustness as other more complex ones  相似文献   
53.
The authors describe PARSEC, a system developed to automate processing, perform endpoint signal analysis, and monitor wafer movement within the plasma area. The system provides automatic downloading of process recipes, detection of defined process problems by the automated analysis of endpoint signals, automatic archiving of these signals, and automated data logging for increased lot-tracking efficiency. The system hardware, software, support tools, implementation, performance and results are described  相似文献   
54.
55.
Quantifying Software Validity by Sampling   总被引:1,自引:0,他引:1  
The point of all validation techniques is to raise assurance about the program under study, but no current methods can be realistically thought to give 100% assurance that a validated program will perform correctly. There are currently no useful ways for quantifying how 'well-validated' a program is. One measure of program correctness is the proportion of elements in the program's input domain for which it fails to execute correctly, since the proportion is zero i.f.f. the program is correct. This proportion can be estimated statistically from the results of program tests and from prior subjective assessments of the program's correctness. Three examples are presented of methods for determining s-confidence bounds on the failure proportion. It is shown that there are reasonable conditions (for programs with a finite number of paths) for which ensuring the testing of all paths does not give better assurance of program correctness.  相似文献   
56.
Results that illustrate the determination of the parameters of a beta prior distribution when either the mean and one percentile or two percentiles are given are presented. Further results show how sensitive the parameters of the beta prior are to errors in the given values. The sensitivity of the probability distribution of the reliability of a system to errors in either the given mean and percentile or the given percentiles of the component beta priors is studied. Included in the study are several systems, ranging from simple ones that occur as subsystems of real systems up to a real type of system consisting of 74 components  相似文献   
57.
This study reports the psychometric properties of a 45-item diabetes-specific questionnaire, the Questionnaire on Stress in Patients with Diabetes—Revised (QSD-R), a modified and shortened version of the QSD (G. Duran et al; see record 1996-18805-001). The QSD-R was filled out by 1,930 individuals with insulin-dependent diabetes mellitus and noninsulin-dependent diabetes mellitus. Eight consistent scales were identified (values of Cronbach's α: .69–.81). The test-retest reliability for the total score after a 5-week interval was rtt?=?.63. The results provide evidence for the reliability and validity of this instrument. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
58.
Wind energy is assessed thermodynamically, from resource and technology perspectives. The thermodynamic characteristics of wind are considered. Wind speed is affected by air temperature and pressure and has an effect on wind turbine performance, based on wind chill effect and Bernoulli's equation. The wind chill effect leads to temperature differences that suggest enthalpy and entropy components must be considered in a thermodynamic analysis. The wind pressure effect based on Bernoulli's equation affects the entropy of wind. These components have not previously been considered in evaluations of wind turbine efficiency for electricity generation. A new efficiency formula for wind energy systems is described, which provides important information about the system. It is seen that average differences between energy and exergy efficiencies are approximately 40% at low wind speeds and up to approximately 55% at high wind speeds. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
59.
Expressed olive juice contains emulsified globules of olive oil. Electron photomicrographs of these globules show a rough membrane protecting them against coalescence. Some features of the membranes, such as the existence of “poles” and deposited microcrystals, are disclosed by the photographs and by electron diffraction patterns. Heavy metals appear to concentrate in the membranes and not in the aqueous medium. Presented at the 50th annual spring meeting, American Oil Chemists' Society, New Orleans, La., April 20–22, 1959.  相似文献   
60.
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