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   1575篇
  免费   20篇
  国内免费   4篇
电工技术   103篇
化学工业   430篇
金属工艺   27篇
机械仪表   31篇
建筑科学   33篇
矿业工程   1篇
能源动力   60篇
轻工业   118篇
水利工程   1篇
石油天然气   1篇
无线电   115篇
一般工业技术   326篇
冶金工业   98篇
原子能技术   52篇
自动化技术   203篇
  2022年   25篇
  2021年   23篇
  2020年   8篇
  2019年   13篇
  2018年   11篇
  2017年   18篇
  2016年   29篇
  2015年   15篇
  2014年   39篇
  2013年   75篇
  2012年   58篇
  2011年   89篇
  2010年   62篇
  2009年   57篇
  2008年   81篇
  2007年   78篇
  2006年   67篇
  2005年   57篇
  2004年   53篇
  2003年   57篇
  2002年   56篇
  2001年   44篇
  2000年   31篇
  1999年   34篇
  1998年   70篇
  1997年   45篇
  1996年   34篇
  1995年   29篇
  1994年   24篇
  1993年   33篇
  1992年   22篇
  1991年   22篇
  1990年   19篇
  1989年   16篇
  1988年   22篇
  1987年   13篇
  1986年   18篇
  1985年   19篇
  1984年   20篇
  1983年   9篇
  1982年   10篇
  1981年   12篇
  1980年   11篇
  1979年   17篇
  1978年   12篇
  1977年   4篇
  1976年   12篇
  1974年   5篇
  1973年   8篇
  1970年   4篇
排序方式: 共有1599条查询结果,搜索用时 15 毫秒
991.
Total mercury (T-Hg), methyl mercury (M-Hg), cadmium (Cd), selenium (Se), zinc (Zn) and copper (Cu) concentrations in the organs of melon-headed whales from a mass stranding on the Japanese coast were analyzed. The mean concentration of T-Hg in the liver (126+/-97 microg/wet g, n=13) was markedly higher than those in kidney (6.34+/-2.36 microg/wet g, n=12) and muscle (4.90+/-2.33 microg/wet g, n=15). In contrast, the mean concentration of M-Hg in the liver (9.08+/-2.24 microg/wet g) was similar to those in the kidney (3.47+/-0.91 microg/wet g) and muscle (3.78+/-1.53 microg/wet g). The mean percentage of M-Hg in the T-Hg found in the liver (13.1+/-10.3) was significantly lower than those in the kidney (58.3+/-15.0) and muscle (78.9+/-8.4). The molar ratio of T-Hg to Se in the liver was effectively 1.0, but those in the kidney and muscle were markedly lower. Conversely, the mean concentration of Cd was markedly higher in the kidney (24.4+/-7.4 microg/wet g) than in the liver (7.24+/-2.08 microg/wet g) and muscle (less than 0.05 microg/wet g). These results suggest that the formation of Hg-Se compounds mainly occurs in the liver after the demethylation of M-Hg, and Cd preferentially accumulates in the kidney of melon-headed whales.  相似文献   
992.
A mixture of tetragonal and monoclinic 2Y˙ZrO2 (2 mol% Y2O3–ZrO2) powder was treated from 400° to 800°C and from 4 to 7 GPa for 30 min. The products were identified by powder XRD, Raman spectroscopy, and TEM. Results indicated that an orthorhombic phase was synthesized at T=400° to 600°C and P>4 GPa. The lattice parameters were obtained as a=0.505, b=0.525, and c=0.509 nm; the density was 6.17 Mg/m3. The orthorhombic phase always coexisted with the tetragonal phase in the products. The amounts of the tetragonal phase before and after treatment remained largely unchanged, whereas the amount of new orthorhombic phase was nearly the same as the decreased amount of the monoclinic phase. It was assumed, therefore, that only the monoclinic phase transformed into the orthorhombic phase.  相似文献   
993.
Applying basically the same innovative and robust fabrication technologies which, for the first time, led to the achievement of remarkably high efficiency of 14.2% at an aperture area of 51.7 cm2 with a Zn(O,S,OH)x buffer layer, the following goals have been targeted: (1) 13% efficiency on a 30 cm×30 cm module and (2) establishment of the fabrication technologies to attain 140 yen/Wp in the annual production capacity of 100 MWp/a. The main focus is currently on the technology development (1) to increase the Voc related to the CIGS absorber and (2) to improve the Jsc related to the DC-sputtered ZnO window layer with a multilayered structure. This contribution well explains the status and strategy of Showa Shell Sekiyu K.K. on the R&D of CIGS-based thin-film modules to achieve the above two goals by the end of FY2000.  相似文献   
994.
We present the International Lattice Data Grid (ILDG), a loosely federated grid-of-grids for sharing data from Lattice Quantum Chromodynamics (LQCD) simulations. The ILDG comprises of metadata, file-format and web-service standards, which can be used to wrap regional data-grid interfaces, allowing seamless access to catalogues and data in a diverse set of collaborating regional grids. We discuss the technological underpinnings of the ILDG, primarily the metadata and the middleware, and offer a critique of its various aspects with the hindsight of the design work and the two years of production.  相似文献   
995.
996.
Crank‐shaped and Y‐shaped through‐hole interconnections (THI) filled with Au‐Sn solder are demonstrated in this study. They are expected to realize a higher‐density wafer‐level package (WLP) for electrical devices including the fields of MEMS (Micro Electro‐Mechanical Systems) and MOEMS (Micro Optical Electro‐Mechanical Systems) compared with conventional WLP using THI consisting of straight through‐holes. In this paper, formation techniques for crank‐shaped and Y‐shaped THI are described. In order to make crank‐shaped and Y‐shaped through‐holes in a substrate, both femtosecond laser irradiation and wet chemical etching are used. Crank‐shaped through‐holes with an 80‐μm opening and 400 μm deep have also been achieved. Gold (Au)‐tin (Sn) solder was filled into the holes using the molten metal suction method (MMSM). Airtightness of the THI was examined using the helium leakage test, and the estimated leakage rate was less than 1.0 × 10?9 Pa·m3/s, which is sufficient for use in WLP applications. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 54–62, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com) . DOI 10.1002/eej.21134  相似文献   
997.
Teams and teamwork are indispensable, especially when tackling difficult and complex tasks that cannot be easily addressed by a single individual. Because breakdowns in team cooperation can cause accidents, much research attention has been devoted to studies on team cooperation and many teamwork models and theories have been proposed. These models and theories are concerned with observable team behaviors like closed-loop communication, backup-behaviors, and a few traits demonstrating good leadership; however, they do not provide a clear explanation for the mechanism behind them. To better understand team cooperation, it is believed to be additionally necessary to clarify the cognitive factors behind team behaviors. This study aims to examine the factors of cognition underlying cooperation and to propose a team cognition model that can describe and explain these factors in team cooperation. As a method to examine the underlying cognitive factors for cooperation, we analyzed participants’ reflection on cooperation and elicited several important factors for cooperation. Then, based on these factors and the findings of both previous studies by team researchers and human cognitive abilities, a team cognition model that can capture a part of the cognitive factors for team cooperation was developed. Suggestive evidence for the importance of metacognition on cooperation was also provided.  相似文献   
998.
The effect of grain boundary cracks on the corrosion behaviour of non-doped aluminium titanate (AT) ceramics was evaluated in a molten Al alloy containing a slight amount of Mg. The corrosion of AT ceramics, in which the AT grains decomposed and subsequently reacted with liquid and/or gaseous Mg to produce MgAl2O4, proceeded not only on sample surfaces in contact and non-contact with the melt, but also on open grain boundary crack surfaces in the ceramic interior. Therefore, the corrosion resistance of AT ceramics can be improved by control of their grain size to close open cracks in the molten alloys.  相似文献   
999.
1000.
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