全文获取类型
收费全文 | 2327篇 |
免费 | 100篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 64篇 |
综合类 | 1篇 |
化学工业 | 451篇 |
金属工艺 | 23篇 |
机械仪表 | 67篇 |
建筑科学 | 61篇 |
能源动力 | 70篇 |
轻工业 | 120篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 443篇 |
一般工业技术 | 479篇 |
冶金工业 | 272篇 |
原子能技术 | 18篇 |
自动化技术 | 354篇 |
出版年
2023年 | 10篇 |
2022年 | 29篇 |
2021年 | 46篇 |
2020年 | 30篇 |
2019年 | 25篇 |
2018年 | 37篇 |
2017年 | 45篇 |
2016年 | 54篇 |
2015年 | 47篇 |
2014年 | 65篇 |
2013年 | 162篇 |
2012年 | 110篇 |
2011年 | 126篇 |
2010年 | 112篇 |
2009年 | 140篇 |
2008年 | 127篇 |
2007年 | 131篇 |
2006年 | 77篇 |
2005年 | 74篇 |
2004年 | 75篇 |
2003年 | 59篇 |
2002年 | 58篇 |
2001年 | 45篇 |
2000年 | 42篇 |
1999年 | 54篇 |
1998年 | 103篇 |
1997年 | 93篇 |
1996年 | 53篇 |
1995年 | 43篇 |
1994年 | 39篇 |
1993年 | 38篇 |
1992年 | 28篇 |
1991年 | 29篇 |
1990年 | 38篇 |
1989年 | 25篇 |
1988年 | 34篇 |
1987年 | 22篇 |
1986年 | 16篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 3篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有2431条查询结果,搜索用时 0 毫秒
71.
Chiang Kao 《International journal of systems science》2013,44(9):1059-1066
This paper discusses the resource allocation problem for not-for-profit organizations that have control over several production units of similar functions. A case of budget allocation among the subdistricts of a forest district in Taiwan is exemplified to illustrate the idea. The model proposed is a nonlinear fractional program superimposed upon the data envelopment analysis framework. This nonlinear fractional program can be transformed to a model similar to the generalized linear program and solved by a type of decomposition method. Within prespecified ranges, the district office searches for ways of allocating a fixed amount of budget to its subdistricts to result in a higher aggregate efficiency score. Wider ranges allow for more flexibility in allocating budget; consequently, higher aggregate efficiency scores are experienced. Since this method is more objective, it is more persuasive to the subdistricts in allocating resources. 相似文献
72.
73.
Abstract This paper investigates the characteristics of acoustic emission (AE) signals generated from hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC) for a medium strength steel in hydrogen sulfide (H2S) solution. The experiments performed in this study include the constant load test (CLT) and the constant extension rate test (CERT). From the results of the CLT, the AE count rate caused by SSCC was found to be much higher than that resulted from the HIC; and the increase of the AE count rate was observed to be approximately proportional to the increase of the applied loading. In addition, the AE frequency distribution diagrams obtained from these tests were found to contain potential information for distinguishing the mechanisms of HIC and SSCC. From the results of CERT, the AE signals detected from the specimens tested in the H2S solution were compared with those obtained from the specimens tested in the air. In addition, the AE count rate detected from the tensile specimens was studied according to the different deformation stages of the specimens. From this study, the variation of the AE count rate in each deformation stage was described. 相似文献
74.
Shih‐Wen Hsiao Yu‐Ting Hsiao Shih‐Kai Chen Chiao‐Fei Hsu Chun‐Hsing Lee Ya‐Hui Chiang 《Color research and application》2016,41(1):72-84
Light‐emitting diodes (LEDs) have the advantage of controllable light colors and provide the optimal lighting quality against various color attributes required in different environments. However, from the humanized design point of view, beside satisfying physical demands of people, it is also important to achieve satisfaction. With a good match between the LED lighting equipment and ambient colors, the space imagery that complies with psychological needs of human beings can be found. This is expected to become a new market direction for future lighting. In this study, the LED light source feature of adjustable correlated color temperature is used to match wall colors of typical commercial spaces and for the investigation and analysis of the impact of colors of light sources and environments on human beings. The measures of mental and subjective feelings of a group of people under various circumstances have also been investigated. Multivariate analysis of variance has been conducted on three color temperatures of light sources, six wall colors, and measures of five emotion adjectives, and the correlation between these three variables has been further investigated. © 2014 Wiley Periodicals, Inc. Col Res Appl, 41, 72–84, 2016 相似文献
75.
Chao-Lung Chiang Kuen-Song Lin Hui-Wen Chuang Chun-Ming Wu 《International Journal of Hydrogen Energy》2017,42(37):23647-23663
Cu/CuCr2O4 catalysts were prepared by impregnation method at various calcination temperatures (300, 400, and 500 °C) and then reduced in H2 stream. The aggregated particles and decreasing surface area/pore volumes of the deactivated catalysts during HCOOH and CH3OH formations were also observed. Particularly, the EXAFS data showed that first shells of Cu atoms transforms from Cu–O to Cu–Cu after catalytic reactions, their bond distances and coordination numbers are quite different, respectively. It revealed that metallic Cu atoms are one of the important active species over catalyst surface at different reaction temperatures having many unoccupied binding sites for HCOOH and CH3OH formations. Additionally, the optimal calcination temperature for Cu/CuCr2O4 catalysts was demonstrated at 400 °C that attributed to its strongest acidity and basicity. The catalytic reactions in the duration of HCOOH and CH3OH preparation were proposed that were composed of HCOOH formation, CH3OH formation, and CH3OH decomposition happening at CuCr2O4, Cu, and CuO active sites, respectively. The highest CO2 conversion (14.6%), HCOOH selectivity/yield (87.8/12.8%), and TON/TOF values (4.19/0.84) were obtained at 140 °C and 30 bar in 5 h, respectively. Optimal rate constant (2.57 × 10?2 min?1) and activation energy (16.24 kJ mol?1) of HCOOH formation were evaluated by pseudo first-order model and Arrhenius equation, respectively. 相似文献
76.
In this paper, we present an interface for the hardware modeled in SystemC to access those modeled in QEMU on a QEMU and SystemC-based virtual platform. By using QEMU as the instruction-accurate instruction set simulator (IA-ISS) and its capability to run a full-fledged operating system such as Linux, the virtual platform with the proposed interface can be used to facilitate the co-design of hardware models and device drivers at the early stage of Electronic System Level (ESL) design flow. In other words, by using such a virtual platform, the hardware models and associated device drivers can be cross verified while they are being developed so that malfunctions in the hardware models or the device drivers can be easily detected. Moreover, the virtual platform with the proposed interface is capable of providing statistics of instructions executed, memory accessed, and I/O performed at the instruction-accurate level—thus not only making it easy to evaluate the performance of the hardware models but also making it possible for design space exploration. 相似文献
77.
For 32/22 nm technology nodes and below, double patterning (DP) lithography has become the most promising interim solutions due to the delay in the deployment of next generation lithography (e.g., EUV). DP requires the partitioning of the layout patterns into two different masks, a procedure called layout decomposition. Layout decomposition is a key computational step that is necessary for double patterning technology. Existing works on layout decomposition are all single-threaded, which is not scalable in runtime and/or memory for large industrial layouts. This paper presents the first window-based parallel layout decomposition methods for improving both runtime and memory consumption. Experimental results are promising and show the presented parallel layout decomposition methods obtain upto 21× speedup in runtime and upto 7.5×reduction in peak memory consumption with acceptable solution quality. 相似文献
78.
79.
80.
Pi-Ju Cheng Chih-Kai Chiang Yi-Cheng Chung Chung-Hao Tien Tzy-Rong Lin 《Nanoscale research letters》2014,9(1):641
We theoretically analyze nanowire-based hybrid plasmonic nanocavities on thin substrates at visible wavelengths. In the presence of thin suspended substrates, the hybrid plasmonic modes, formed by the coupling between a metal nanowire and a dielectric nanowire with optical gain, exhibit negligible substrate-mediated characteristics and overlap better with the gain region. Consequently, the confinement factor of the guided hybrid modes is enhanced by more than 42%. However, the presence of significant mirror loss remains the main challenge to lasing. By adding silver coatings with a sufficient thickness range on the two end facets, we show that the reflectivity is substantially enhanced to above 50%. For a coating thickness of 50 nm and cavity length of about 4 μm, the quality factor is above 100. 相似文献