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   755篇
  免费   17篇
  国内免费   1篇
化学工业   36篇
金属工艺   3篇
机械仪表   34篇
建筑科学   5篇
能源动力   4篇
轻工业   13篇
水利工程   3篇
石油天然气   3篇
无线电   96篇
一般工业技术   111篇
冶金工业   394篇
原子能技术   1篇
自动化技术   70篇
  2023年   5篇
  2022年   5篇
  2021年   11篇
  2020年   6篇
  2019年   19篇
  2018年   9篇
  2017年   6篇
  2016年   12篇
  2015年   9篇
  2014年   18篇
  2013年   25篇
  2012年   30篇
  2011年   35篇
  2010年   21篇
  2009年   15篇
  2008年   19篇
  2007年   11篇
  2006年   13篇
  2005年   12篇
  2004年   9篇
  2003年   16篇
  2002年   11篇
  2001年   9篇
  2000年   6篇
  1999年   9篇
  1998年   127篇
  1997年   79篇
  1996年   50篇
  1995年   26篇
  1994年   29篇
  1993年   32篇
  1992年   5篇
  1991年   6篇
  1990年   11篇
  1989年   9篇
  1988年   5篇
  1987年   6篇
  1986年   3篇
  1985年   3篇
  1984年   1篇
  1982年   5篇
  1981年   9篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   5篇
  1976年   13篇
  1972年   1篇
  1971年   1篇
排序方式: 共有773条查询结果,搜索用时 990 毫秒
21.
Monodisperse copolymer particles carrying surface carboxyl groups in the range of 50–200 μm were prepared by in situ UV polymerization of ethyleneglycol dimethacrylate (EGDMA) with acrylic acid (AA) via a microfluidic flow-focusing device (MFFD). The design of the coaxial orifices in the MFFD enables the confinement of the comonomer liquid thread to the central axis of the microchannel, which can avoid the wetting problem of comonomer liquid with the microchannel and can successfully produce monodisperse copolymer microspheres with coefficient of variance below 5%. The effects of concentration of EGDMA and AA on droplet diameters and the distribution of carboxyl group on particle surfaces were examined. It has been found that, increasing the concentration of AA would decrease particle sizes, but increase the distribution of carboxyl group on particle surfaces. Bioconjugation of the carboxylated copolymer particles with the anti-rabbit IgG–Cy3 conjugates was successfully demonstrated. By increasing the concentration of AA accompanied with decreasing the particle sizes, high efficiency of bioconjugation on carboxylated copolymer particles was achieved. The rapid continuous synthesis of carboxylated copolymer particles via a microfluidic device provides a reliable control of particle sizes and composition for massive production in biotechnological applications.  相似文献   
22.
A semicircle control chart can be used in detecting both increases and decreases in the mean and/or variance. In this paper, we propose two modified semicircle charts for detecting a reduction in the process variance, a.k.a. process improvement. Each of these modified semicircle charts, namely, SC1 and SC2 has two limits, defined by the inner and outer semicircles. A process improvement is detected by the SC1 scheme if a point is plotted inside the smallest semicircle, or if two successive points are plotted between the inner and outer semicircles and by the SC2 scheme if a point plots inside the smallest semicircle or if two of three successive points plot between the inner and outer semicircles. It will be shown that the two modified semicircle charts have superior average run length (ARL) performances to the basic semicircle chart in the detection of process improvement. The ARL study is conducted by means of a simulation.  相似文献   
23.
In component-based software development, gluing of two software components is usually achieved by defining an interface specification, and creating wrappers on components to support the interface. We believe that interface specification provides useful information for specializing components. An interface may define constraints on a component's inputs, as well as on its outputs. In this paper, we propose a new approach to program specialization with respect to output constraints. We provide the form in which an efficient specialized program should be after such specialization, and consider a variant of partial evaluation to achieve it. In the process, we translate an output constraint into a characterization function for a component's input, and define a specializer that uses this characterization to guide the specialization process. We believe this work will broaden the scope of program specialization, and provide a framework for building more generic and versatile program adaptation techniques.  相似文献   
24.
The inherent dynamic relationships among design tasks performed concurrently at different organizations characterize the complexities of a design chain where designers with diverse expertise need to collaborate across organizational boundaries. To ensure timely completion of inter-related design tasks, metrics to facilitate the early evaluation of design concepts are crucial. The ability to evaluate and select suitable design concepts at an early stage will ensure better solutions and greater savings in time and effort further downstream. This paper proposes a new approach based on the rough set theory to design concept analysis. The approach aims at early detection of design inadequacy. A so-called information system is constructed using the information gleaned from design concepts and design capabilities, and analyzed using the rough set theory to derive a set of design rules for design concept analysis. The approach embodies a technique for handling attributes with unavailable information, which is a frequent occurrence in design. This paper presents details of the proposed approach, the novel technique, and a case study.  相似文献   
25.
A novel method called Impact-synchronous modal analysis (ISMA) was proposed previously which allows modal testing to be performed during operation. This technique focuses on signal processing of the upstream data to provide cleaner Frequency response function (FRF) estimation prior to modal extraction. Two important parameters, i.e., windowing function and impact force level were identified and their effect on the effectiveness of this technique were experimentally investigated. When performing modal testing during running condition, the cyclic loads signals are dominant in the measured response for the entire time history. Exponential window is effectively in minimizing leakage and attenuating signals of non-synchronous running speed, its harmonics and noises to zero at the end of each time record window block. Besides, with the information of the calculated cyclic force, suitable amount of impact force to be applied on the system could be decided prior to performing ISMA. Maximum allowable impact force could be determined from nonlinearity test using coherence function. By applying higher impact forces than the cyclic loads along with an ideal decay rate in ISMA, harmonic reduction is significantly achieved in FRF estimation. Subsequently, the dynamic characteristics of the system are successfully extracted from a cleaner FRF and the results obtained are comparable with Experimental modal analysis (EMA).  相似文献   
26.
在iPhoneg和iPad的推动下,智能手机和平板电脑中的触控屏应用急剧增长,从而导致触摸控制器出货量在未来短短五年将增长近两倍。  相似文献   
27.
Creating copy-move forgery became even easier using a wide range of software and platforms. Many algorithms have been proposed to solve the problem, but each one of those algorithms has its own drawbacks. Researchers face many challenges in developing copy-move detection algorithms, and in this paper, we focus on two challenges. The first is the benchmark dataset, and the second involves evaluation metrics. In this paper, we investigate the available copy-move datasets and their advantages and disadvantages. In addition, we discuss the different metrics that have been used by researchers to evaluate the copy-move forgery detection (CMFD) algorithms. On that basis, we suggest the standard specifications of the appropriate copy-move dataset and the metrics that should be used to evaluate the detection algorithms. The findings of this paper will help researchers evaluate their algorithms effectively and fairly essential for developing reliable algorithms.  相似文献   
28.
This paper presents analytical and numerical results for Poiseuille flow through microtubes patterned with superhydrophobic surfaces which consist of alternative ribs and grooves aligned longitudinally with the flow direction. The superhydrophobic surface prevents the flowing liquid from penetrating the grooves and the liquid–gas interface experiences deformation as a consequence of a pressure difference across the interface. Employing a domain perturbation technique, the effects of a small interface deformation on the effective slip behavior are analytically quantified. For large interface deformations, numerical studies are performed to predict the effects of interface protrusion on the effective slip behavior of the superhydrophobic microtube. Comparisons are made between the effective slip behavior for tube and channel flows patterned with superhydrophobic surfaces containing alternating longitudinal ribs and grooves.  相似文献   
29.
Control charts for monitoring the coefficient of variation (γ) are useful for processes with an inconsistent mean (μ) and a standard deviation (σ) which changes with μ, by monitoring the consistency in the ratio σ over μ. The synthetic-γ chart is one of the charts proposed to monitor γ, and its attractiveness lie in waiting until a second point to fall outside the control limits before a decision is made. However, existing synthetic-γ charts do not differentiate between the points falling outside the upper control limit (UCL) and lower control limit (LCL). Hence, this paper proposes a side-sensitive synthetic-γ chart, where successive nonconforming samples must either fall above the UCL or below the LCL. Formulae to compute the average run length (ARL), the standard deviation of the run length (SDRL) and expected average run length (EARL) are derived using the Markov chain approach, and the algorithms to obtain the optimal charting parameters are proposed. Subsequently, the optimal charting parameters, ARL, SDRL and EARL values for various numerical examples are shown. Comparisons show that the side-sensitive synthetic-γ chart consistently outperforms the existing synthetic-γ chart, especially for small shifts. The proposed chart also consistently outperforms the Shewhart-γ chart, while showing comparable or better performance than the Exponentially Weighted Moving Average (EWMA) chart for most shift sizes, except for very small shifts. Finally, this paper shows the implementation of the proposed chart on an industrial example.  相似文献   
30.
The progressive mean (PM) statistic is based on a simple idea of accumulating information of each subgroup by calculating the average progressively. Its weighting structure is based on a subgroup number that changes arithmetically, which makes the PM chart unique and efficient compared with the existing classical memory control charts. In a recent article (see reference 1), it was claimed that the PM chart is a special case of the exponentially weighted moving average (EMWA) chart. In this article, it is shown that even though the PM statistic can be written in the form of an EWMA statistic, the variance of the PM statistic is different from that of the EWMA statistic. Consequently, the limits of the PM chart are different from that of the EWMA chart. Therefore, it is found that the PM chart is not a special case of the EWMA chart; hence, the claim in reference 1 is incorrect. Furthermore, it is pointed out in this paper that no adaptive property in the weighting parameter of the PM statistic exists, further contradicting the claim in reference 1.  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