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   1728篇
  免费   29篇
  国内免费   2篇
电工技术   104篇
化学工业   292篇
金属工艺   67篇
机械仪表   35篇
建筑科学   23篇
矿业工程   1篇
能源动力   60篇
轻工业   129篇
水利工程   1篇
石油天然气   2篇
无线电   157篇
一般工业技术   254篇
冶金工业   519篇
原子能技术   32篇
自动化技术   83篇
  2023年   8篇
  2022年   22篇
  2021年   32篇
  2020年   11篇
  2019年   17篇
  2018年   26篇
  2017年   18篇
  2016年   27篇
  2015年   17篇
  2014年   32篇
  2013年   77篇
  2012年   42篇
  2011年   71篇
  2010年   41篇
  2009年   53篇
  2008年   60篇
  2007年   40篇
  2006年   40篇
  2005年   51篇
  2004年   40篇
  2003年   46篇
  2002年   33篇
  2001年   46篇
  2000年   35篇
  1999年   52篇
  1998年   177篇
  1997年   125篇
  1996年   86篇
  1995年   47篇
  1994年   64篇
  1993年   49篇
  1992年   24篇
  1991年   16篇
  1990年   13篇
  1989年   20篇
  1988年   11篇
  1987年   18篇
  1986年   16篇
  1985年   28篇
  1984年   10篇
  1983年   16篇
  1982年   8篇
  1981年   10篇
  1980年   13篇
  1978年   7篇
  1977年   19篇
  1976年   19篇
  1975年   5篇
  1973年   4篇
  1968年   4篇
排序方式: 共有1759条查询结果,搜索用时 31 毫秒
51.
52.
53.
54.
55.
Many research groups are developing series voltage compensators. In a series converter, since a transformer is used in series in the power system, the power system current flows into the voltage source inverter through the transformer. The inverter current, which is determined by the transformation ratio, gives rise to an error voltage that consists of a dead‐time voltage and an impedance voltage. The error voltage is generated even when the reference voltage is zero. This paper describes the mechanism by which the error voltage occurs and proposes a method for reducing the error voltage. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 85–93, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22333  相似文献   
56.
A molecular glass resist with an ionic photoacid generator and a single protection group (MR‐1) has been developed. MR‐1 exhibited good thermal properties, such as a 5% weight loss temperature (Td5%) of 167°C and a glass transition temperature (Tg) of 80°C. MR‐1 showed the good sensitivity of 80 μC/cm2 and high contrast of 4.9 with e‐beam exposure (50 keV). A relatively high resolution of 50 nm and low Line‐Edge‐Roughness of 3.8 nm were obtained by e‐beam exposure (100 keV). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39769.  相似文献   
57.
Journal of Mechanical Science and Technology - Recently, domestic gas turbines are primarily operated under partial loads. Hence, thermal expansion of components decreases, leading to a...  相似文献   
58.
The generalized scaling law is based on the concept of two-stage scaling and allows currently available centrifuge facilities to model a large-scale prototype expanding over the spatial dimension ranging from 30 m or larger subject to earthquake motions. This paper presents the results of investigation on the applicability of the generalized scaling law to the fully nonlinear regime of soil-structure system with the induced strain level of 10% in the order of magnitude. The centrifuge model tests performed in this study under the modeling of models scheme consist of a pile model embedded in a inclined ground subject to liquefaction-induced lateral spreading. Four different centrifugal accelerations ranging from 13g to 50g are used whereas the actual size of the physical model is kept constant with an overall scaling factor of 1/100. The models are exposed to tapered sinusoidal input accelerations of frequency 0.59 Hz and amplitude 3.0 m/s2 in prototype scale, and the results are compared in terms of prototype by applying the generalized scaling law. As for the response of the ground during shaking, essentially identical accelerations and excess pore water pressures are recorded for all cases, while the lateral displacement shows a variation ranging from 5% to 9% in terms of shear strain due to a slight variation in experimental conditions (e.g., input peak acceleration, achieved density distribution). Practically the same responses are measured among the cases in the dissipation phase of excess pore water pressure. With regard to pile behavior, nearly identical responses for the lateral displacements and bending moments are obtained for all cases both during and after shaking. These results demonstrated that the generalized scaling law is applicable to the fully nonlinear regime of soil-structure system subject to the cumulative shear strain in the order of 10% due to cyclic mobility of sands during earthquakes.  相似文献   
59.
Metallurgical and Materials Transactions B - A two-step plasma arc melting process, comprising a first step under Ar-30 pct H2 gas flow and the second step under Ar gas flow, has been...  相似文献   
60.
The effects of fatty acid, monoacylglycerol, and polyglycerol fatty acid ester with varying chain length in their acyl chains on the extent of complex formation (complex index) and in vitro enzymatic digestibility of gelatinized potato starch were investigated. The complex index increased with increase in the concentration of the ligands (fatty acid, monoacylglycerol, and polyglycerol fatty acid ester), with the plateau in the complex index value depending on the type of ligands. In comparison of complex index among fatty acid-samples, the complex index maximum increased as the chain length increased up to octanoic acid and then decreased. In comparison of complex index among fatty acid-, monoacylglycerol-, and polyglycerol fatty acid ester-samples at each acyl chain, the complex index maximum followed the order polyglycerol fatty acid ester > monoacylglycerol > fatty acid. Fatty acid, monoacylglycerol, and polyglycerol fatty acid ester with long acyl chains greatly reduced the enzymatic hydrolysis of starch. Polyglycerol fatty acid ester with palmitic acid chains was the strongest inhibitor of starch hydrolysis, suggesting that further complex formation may occur during the hydrolysis of gelatinized starch (enzyme-annealing).  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