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   635篇
  免费   3篇
  国内免费   4篇
电工技术   6篇
综合类   2篇
化学工业   134篇
金属工艺   17篇
机械仪表   15篇
建筑科学   36篇
能源动力   21篇
轻工业   38篇
水利工程   2篇
石油天然气   2篇
无线电   60篇
一般工业技术   170篇
冶金工业   23篇
原子能技术   6篇
自动化技术   110篇
  2022年   4篇
  2021年   15篇
  2020年   5篇
  2018年   9篇
  2017年   7篇
  2016年   8篇
  2015年   4篇
  2014年   10篇
  2013年   28篇
  2012年   24篇
  2011年   33篇
  2010年   22篇
  2009年   28篇
  2008年   40篇
  2007年   31篇
  2006年   19篇
  2005年   30篇
  2004年   18篇
  2003年   17篇
  2002年   24篇
  2001年   12篇
  2000年   19篇
  1999年   17篇
  1998年   12篇
  1997年   6篇
  1996年   12篇
  1995年   8篇
  1994年   9篇
  1993年   4篇
  1992年   10篇
  1991年   6篇
  1990年   6篇
  1989年   8篇
  1988年   8篇
  1987年   11篇
  1986年   9篇
  1985年   8篇
  1984年   9篇
  1983年   8篇
  1982年   11篇
  1981年   12篇
  1980年   4篇
  1979年   4篇
  1978年   6篇
  1977年   9篇
  1976年   6篇
  1975年   7篇
  1974年   5篇
  1973年   7篇
  1967年   2篇
排序方式: 共有642条查询结果,搜索用时 15 毫秒
1.
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) X¯ scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA X¯ scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA X¯ scheme.  相似文献   
2.
Solubilities and diffusivities of carbon dioxide and nitrous oxide in a mixture of toluene and isopropanol organic solution of cyclohexylamine were measured at 20°C in the range of pressures of solute from 1 to 3 bars. This was performed with an original chromatographic technique taking into account the presence of the product of the reaction.  相似文献   
3.
A new algorithm for reducing control points in lofted surface interpolation to rows of data points is presented in this paper. The key step of surface lofting is to obtain a set of compatible B-spline curves interpolating each row. Given a set of points and their parameterization, a necessary and sufficient condition is proposed to determine the existence of interpolating B-spline curves defined on a given knot vector. Based on this condition, we first properly construct a common knot vector that guarantees the existence of interpolating B-spline curves to each row of points. Then we calculate a set of interpolating B-spline curves defined on the common knot vector by energy minimization. Using this method, fewer control points are employed while maintaining a visually pleasing shape of the lofted surface. Several experimental results demonstrate the usability and quality of the proposed method.  相似文献   
4.
Glycoproteinoses, Pompe disease, and sialic acid storage diseases are characterized by a massive accumulation of unprocessed oligosaccharides and/or glycoconjugates in urine. The identification of these glycocompounds is essential for a proper diagnosis. In this study, we investigated the potential of MALDI‐TOF‐MS to identify glycocompounds present in urine from patients with different inborn errors of glycan metabolism. Urinary glycocompounds were permethylated, and analyzed using GC‐MS and MALDI‐TOF‐MS. In order to confirm tentative assignments, a second aliquot of urine was purified on a C18 Sep‐Pak cartridge and glycocompounds were desalted on a column of nonporous graphitized carbon. The glycocompounds were then sequentially on‐plate digested using an array of exoglycosidases. A range of disease‐specific oligosaccharides as well as glycopeptides was identified for all oligosacchariduria models. In addition, free sialic acid accumulated in urine from a patient suffering from French‐type sialuria, has been detected by a GC‐MS approach, which could be applied to other sialic acid storage diseases. This procedure is simple, and can be performed in few simple steps in less than 24 h. This current method can be applied for newborn screening for other inherited metabolic diseases as well as for assessing treatments in clinical trials.  相似文献   
5.
This paper presents results showing the robustness of different SiC JFET transistors from SiCED in current limitation regime or short-circuit operation. Crystal temperature during failure was estimated after different electrical characterizations and using appropriate models of saturation current which is used as a thermal indicator. This work shows the exceptional robustness of SiC JFET transistors in current limitation mode compared to Si devices (MOSFETS and IGBTs).  相似文献   
6.
超短高功率脉冲激光与物质相互作用及其应用   总被引:5,自引:1,他引:5  
江志明  徐至展 《中国激光》1996,23(6):513-519
超短高功率脉冲激光系统的小型化实用化极大地促进了激光与物质相互作用的物理和应用研究。回顾加拿大魁北克大学国立科学研究院材料研究所(简称INRS)的超短高功率脉冲激光产生高温高密度等离子体的最新研究成果及其在分子物理和辐射约束高温高密度等离子体物理中的应用。  相似文献   
7.
A thermodynamic modeling of GaN was carried out to describe the thermodynamic behavior of native defects, dopants, and carriers (free electrons and holes) in GaN semiconductors. The compound energy model (CEM) was used. An unintentionally doped GaN was taken as an example. Oxygen was introduced into the model as the unintentionally doped impurity, according to the practical experimental phenomena. The energies of component compounds in the model were defined based on the results of the ab initio calculations and adjusted to fit experimental data. The thermodynamic properties of the defects and the oxygen doped were calculated to show the facility of the model.  相似文献   
8.
The commonly used IP-backbone network architecture of today is IP/ATM/SDH/WDM. This architecture has many redundant functionalities and is not optimized to transport IP traffic. New approaches for simplified network architectures try to eliminate redundant functionalities and to decrease the protocol overhead and thereby transport IP as efficiently as possible over WDM-based optical networks. EURESCOM project P918 Integration of IP-over-optical networks: networking and management investigated scenarios for optimized IP transport in WDM-based backbone networks. In this paper, three architectures, namely Gigabit Ethernet, Packet over Sonet/SDH and Dynamic Packet Transport are investigated and evaluated as an alternative to the IP/ATM/SDH/WDM architecture.  相似文献   
9.
Runs-rules have been widely used since the 1950s in industrial and nonindustrial process monitoring applications to improve the performance of basic and other traditional monitoring schemes. However, none of the studies on runs-rules have accounted for a process with a combined effect of measurement errors and autocorrelation. Hence, in this paper, the use of the w-of-w runs-rules to improve the performance of the Shewhart X¯ scheme using an additive model with a constant variance and a first-order autoregressive model is proposed. To reduce the combined negative effect of measurement errors and autocorrelation, we implement a sampling strategy based on rational subgroups in which (a) multiple measurements per item are taken (instead of a standard single measurement) and (b) non-neighboring observations are gathered. Moreover, the latter sampling strategy is incorporated into the values of probability elements of a Markov chain matrix which is used to derive some closed-form expressions for the zero- and steady-state run-length distribution. The main finding of this study is that, with respect to some overall performance measures, the proposed scheme outperforms the existing Shewhart X¯ scheme by a significant margin. A real-life example is used to illustrate the practical implementation of the proposed scheme.  相似文献   
10.
The complete sequence of a 40 247 bp DNA segment located on the left arm of chromosome X of Saccharomyces cerevisiae has been determined and analysed. The sequence encodes the 5′ coding region of the URA2 gene and 18 open reading frames of at least 100 amino acids. Ten of these correspond to known genes, whereas eight correspond to new genes. In addition, the sequence contains a tRNA-Ala gene, a tRNA-Asp gene, a Ty4 transposable element and three delta elements. The sequence has been deposited in the EMBL databank under Accession Numbers: Z49405, Z49404, Z49403, Z49402, Z49401, Z49400, Z49399, Z49398, Z49397, Z49396, Z49394, Z49392, Z49391, Z49390, Z49389, Z49387, Z49386, Z49385.  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