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   228篇
  免费   5篇
电工技术   7篇
化学工业   40篇
金属工艺   6篇
机械仪表   2篇
建筑科学   7篇
矿业工程   2篇
能源动力   3篇
轻工业   19篇
水利工程   3篇
石油天然气   1篇
无线电   33篇
一般工业技术   35篇
冶金工业   34篇
原子能技术   3篇
自动化技术   38篇
  2023年   1篇
  2022年   3篇
  2021年   8篇
  2020年   5篇
  2019年   7篇
  2018年   3篇
  2017年   4篇
  2016年   7篇
  2015年   4篇
  2014年   12篇
  2013年   11篇
  2012年   13篇
  2011年   11篇
  2010年   10篇
  2009年   7篇
  2008年   8篇
  2007年   10篇
  2006年   10篇
  2005年   6篇
  2004年   6篇
  2003年   9篇
  2002年   10篇
  2001年   2篇
  2000年   4篇
  1999年   4篇
  1998年   6篇
  1997年   8篇
  1996年   3篇
  1995年   4篇
  1993年   5篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1988年   6篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   4篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1968年   1篇
  1965年   1篇
排序方式: 共有233条查询结果,搜索用时 15 毫秒
91.
Design-for-test methodologies have enabled considerable reduction in test time and improvement in defect isolation. Defects which impede correct operation of scan chains are a significant fraction of yield loss. Isolating these defects is an important but underserved activity.Image-based technologies examining an extended area of die are popular diagnostics techniques because they provide intuitive and useful results. Emission based microscopy and laser fault isolation techniques, both static and dynamic, are readily available. However, neither technique provides insight to specific timing characteristics of the IC. Photoemission microscopy suffers from decreasing signal strength at lower voltages, and laser techniques can be difficult to perform with production test setups, requiring involved test pattern and setup adaptation.In this paper, we describe two scan chain defect localization case studies using Laser Voltage Imaging [1] on 40 nm bulk CMOS technology operating at 0.9 V. Results are also compared to other diagnostics techniques, including software-based shift analysis and photoemission microscopy.  相似文献   
92.
High-temperature, high-velocity water vapor (steam-jet) exposures were conducted on Y2O3, Y2SiO5, Y2Si2O7, and SiO2 for 60 hours at 1400°C. Volatility of Y2O3 was not observed. Phase-pure Y2SiO5 exhibited SiO2 loss forming Y2O3 and porosity. A mixed porous and dense Y2SiO5 layer formed on the surface of Y2Si2O7 due to SiO2 depletion. The mechanisms and kinetics of the reaction between SiO2 and H2O(g) to form Si(OH)4(g) from Y2SiO5, Y2Si2O7, and SiO2 are discussed.  相似文献   
93.
Gasoline Compression Ignition (GCI) engines have the potential to achieve high fuel efficiency and to significantly reduce both NOx and particulate matter (PM) emissions by operating under dilute, partially-premixed conditions. This low temperature combustion strategy is dependent upon direct-injection of gasoline during the compression stroke and potentially near top dead center (TDC). The timing and duration of the in-cylinder injections can be tailored based on speed and load to create optimized conditions that result in a stable combustion.  相似文献   
94.
95.
Accurate simulation of power-systems dynamics over an extended time period results in a model that is relatively stiff; the solution of such models requires a numerical integration method that is not only fast and accurate, but also capable of using long time steps. An integration method which can be numerically tuned to suit the system of equations is developed and is shown to be superior to the trapezoidal rule when very long time steps are used. While the fixed-tuning methods are easy to implement, they are not recommended since they resulted in no significant improvements. Adaptively tuned techniques performed better and some worthwhile gains were obtained with long time steps  相似文献   
96.
A simple, rapid, and accurate numerical method is presented for calculating the shielding effectiveness and the light transmittance of multilayered media. A uniform treatment is used to obtain the shielding effectiveness of the layers at microwave frequencies and their light transmittance at optical frequencies. The method is completely general and does not involve any approximation. It can be applied at any frequency, for vertical or oblique incidence, to lossless or lossy, isotropic or anisotropic media consisting of any number of dielectric and metallic layers. In order to illustrate the versatility of the method, the shielding effectiveness and the light transmittance of two different structures consisting of a gold film deposited over a plastic substrate and of a plastic substrate sandwiched between two gold films are analyzed under different conditions  相似文献   
97.
We suggest Darwinian Networks (DNs) as a simplification of working with Bayesian networks (BNs). DNs adapt a handful of well‐known concepts in biology into a single framework that is surprisingly simple yet remarkably robust. With respect to modeling, on one hand, DNs not only represent BNs but also faithfully represent the testing of independencies in a more straightforward fashion. On the other hand, with respect to three exact inference algorithms in BNs, DNs simplify each of them while unifying all of them. DNs can determine good elimination orderings using the same platform as used for modeling and inference. Finally, we demonstrate how DNs can represent two additional frameworks. Practical benefits of DNs include faster algorithms for inference and modeling.  相似文献   
98.
A 3.0-m-long, 150-microm-wide, 240-microm-deep channel etched in a 3.2-cm-square silicon chip, covered with a Pyrex wafer, and coated with a dimethyl polysiloxane stationary phase is used for the GC separation of volatile organic compounds. The column, which generates approximately 5500 theoretical plates, is temperature-programmed in a conventional convection oven. The column is connected through a heated transfer line to a microfabricated differential mobility spectrometer. The spectrometer incorporates a 63Ni source for atmospheric-pressure chemical ionization of the analytes. Nitrogen or air transport gas (flow 300 cm(3)/min) drives the analyte ions through the cell. The spectrometer operates with an asymmetric radio frequency (RF) electric field between a pair of electrodes in the detector cell. During each radio frequency cycle, the ion mobility alternates between a high-field and a low-field value (differential mobility). Ions oscillate between the electrodes, and only ions with an appropriate differential mobility reach a pair of biased collectors at the downstream end of the cell. A compensation voltage applied to one of the RF electrodes is scanned to allow ions with different differential mobilities to pass through the cell without being annihilated at the RF electrodes. A unique feature of the device is that both positive and negative ions are detected from a single experiment. The combined microfabricated column and detector is evaluated for the analysis of volatile organic compounds with a variety of functionalities.  相似文献   
99.
Using mRNA to produce therapeutic proteins is a promising approach to treat genetic diseases. However, systemically delivering mRNA to cell types besides hepatocytes remains challenging. Fast identification of nanoparticle delivery (FIND) is a DNA barcode‐based system designed to measure how over 100 lipid nanoparticles (LNPs) deliver mRNA that functions in the cytoplasm of target cells in a single mouse. By using FIND to quantify how 75 chemically distinct LNPs delivered mRNA to 28 cell types in vivo, it is found that an LNP formulated with oxidized cholesterol and no targeting ligand delivers Cre mRNA, which edits DNA in hepatic endothelial cells and Kupffer cells at 0.05 mg kg?1. Notably, the LNP targets liver microenvironmental cells fivefold more potently than hepatocytes. The structure of the oxidized cholesterols added to the LNP is systematically varied to show that the position of the oxidative modification may be important; cholesterols modified on the hydrocarbon tail associated with sterol ring D tend to outperform cholesterols modified on sterol ring B. These data suggest that LNPs formulated with modified cholesterols can deliver gene‐editing mRNA to the liver microenvironment at clinically relevant doses.  相似文献   
100.
This study examines how demographic variables affect willingness to disclose and perceived risks of disclosing personally identifying information (PII, also referred to as personal data in Europe) in ecommerce in the United States and Estonia. The study utilized a 17-item list of potential disclosure items (name, email address, etc.), categorized reliably into six sub-indices: contact information, payment information, life history information, financial/medical information, work-related information, and online account information. Online disclosure consciousness (ODC) is introduced as a framework to conceptualize, explain the study’s findings, and empirically measure the gap between one’s willingness to disclose and perceived risk pertaining to the overall 17-item index used in the study, the sub-indices, and particular items. The results show significant gaps among participants both within and across nations. Despite Estonia’s advanced adoption and progressive policies and practices toward the Internet, Americans are more willing to disclose, and less concerned about perceived risks. The findings suggest willingness to disclose and risk aversion can and should be analyzed empirically together. The theoretical model provides an alternative conceptualization to the ideas of the privacy paradox, privacy calculus, and privacy cost-benefit ratios. Implications for theory, consumers, marketing practice, and public policy are discussed. Importantly, the study can inform increased adoption of ecommerce and the digital economy, while also protecting consumer’s personal data.  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