全文获取类型
收费全文 | 11893篇 |
免费 | 1003篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 217篇 |
综合类 | 11篇 |
化学工业 | 3097篇 |
金属工艺 | 437篇 |
机械仪表 | 690篇 |
建筑科学 | 168篇 |
矿业工程 | 2篇 |
能源动力 | 659篇 |
轻工业 | 1164篇 |
水利工程 | 40篇 |
石油天然气 | 11篇 |
武器工业 | 2篇 |
无线电 | 1897篇 |
一般工业技术 | 2833篇 |
冶金工业 | 487篇 |
原子能技术 | 183篇 |
自动化技术 | 1033篇 |
出版年
2024年 | 12篇 |
2023年 | 140篇 |
2022年 | 234篇 |
2021年 | 352篇 |
2020年 | 282篇 |
2019年 | 353篇 |
2018年 | 419篇 |
2017年 | 423篇 |
2016年 | 538篇 |
2015年 | 425篇 |
2014年 | 638篇 |
2013年 | 774篇 |
2012年 | 877篇 |
2011年 | 1070篇 |
2010年 | 734篇 |
2009年 | 780篇 |
2008年 | 669篇 |
2007年 | 574篇 |
2006年 | 455篇 |
2005年 | 380篇 |
2004年 | 355篇 |
2003年 | 321篇 |
2002年 | 309篇 |
2001年 | 270篇 |
2000年 | 247篇 |
1999年 | 215篇 |
1998年 | 237篇 |
1997年 | 162篇 |
1996年 | 134篇 |
1995年 | 108篇 |
1994年 | 69篇 |
1993年 | 70篇 |
1992年 | 43篇 |
1991年 | 31篇 |
1990年 | 35篇 |
1989年 | 39篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1975年 | 4篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
We present a structured procedure for order pick system (OPS) analysis and design that has been established on literature review and interviews with and presentations to OPS experts. In particular, we attempt to include the thinking processes that occur between OPS designers and owners. The design procedure and related issues are discussed in the order of input, selection, and evaluation stages. 相似文献
43.
44.
Tae Geun Kim Kyung Hyun Park Sung-Min Hwang Yong Kim Eun Kyu Kim Suk-Ki Min Si-Jeong Leem Jong-Il Jeon Jung-Ho Park Chang W.S.C. 《Quantum Electronics, IEEE Journal of》1998,34(8):1461-1468
GaAs-AlGaAs V-grooved inner stripe (VIS) quantum-well wire (QWW) lasers grown by metalorganic chemical vapor deposition with different current blocking configurations, n-blocking on p-substrate (VIPS), p-n-p-n blocking on n-substrate (VI(PN)nS) and p-blocking on n-substrate (VINS) have been fabricated and characterized. The VIPS QWW lasers show the most stable characteristics with effective current confinement: one of the lasers shows fundamental transverse mode, lasing up to 5 mW/facet, typical threshold current of 39.9 mA at 818.5 mm, an external differential quantum efficiency of 24%/facet, and characteristic temperature of 92 K. The current tuning rate was almost linear at 0.031 mm/mA, and the temperature tuning rate was measured to be 0.14 nm/°C. Comparison of the light output versus current characteristics of the lasers with different current blocking configurations is presented here 相似文献
45.
The purpose of this study was to analyze the symbolization of colors as cultural codes, based on costume colors. In order to study the significance of colors in cultural changes, we carried out a quantitative analysis and interpreted it from the perspective of cultural semiotics. The range of this study was focused on Korean costume colors, over diverse diachronic stages of Korean culture. For this study 1535 color samples were collected, measured with a spectrophotometer, and analyzed quantitatively according their diachronic stages of origin. As a result, red, blue, and yellow were found to be the most frequently used colors during the Chosun Dynasty, a period based on Confucianism. These colors acted as cultural codes with cultural significance. During the Modern times pink, light blue, and black increased in frequency and represented the reception of western culture, the changing sex role of women in society, and utilitarianism. In these days, neutral colors and grayish tones of all colors are the most significant colors of high frequency. The use of such colors is closely related to industrialization, mechanization, functionalism, and the changes of women's sex roles in the societies. They are used as cultural codes, especially to emphasize a rational and masculine image rather than a feminine image. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 71–79, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20290 相似文献
46.
In this work, we designed, fabricated and tested a disposable, flow-through amperometric sensor for free chlorine determination in water. The sensor is based on the principle of an electrochemical cell. The substrate, as well as the top microfluidic layer, is made up of a polymer material. The advantages include; (a) disposability from low cost; (b) stable operation range from three-electrode design; (c) fluidic interconnections that provide on line testing capabilities; and (d) transparent substrate which provides for future integration of on-chip optics. The sensor showed a good response and linearity in the chlorine concentration ranging from 0.3 to 1.6 ppm, which applies to common chlorination process for drinking water purification. 相似文献
47.
48.
Jung‐Hyun Cho Michael Bass Hans P. Jenssen 《Journal of the Society for Information Display》2007,15(12):1029-1036
Abstract— Several rare‐earth‐doped fluoride crystals that are excited to emit visible light by sequential two‐photon absorption have been investigated as display‐medium candidates for static volumetric three‐dimensional displays. Dispersion of powders of these materials in a refractive‐index‐matched polymer is reported because such a medium may result in a scalable display. The scattering problem in such a medium is greatly reduced by index‐matching the polymer to the crystalline particles. An index‐matching condition that optimizes the performance is identified. 相似文献
49.
Surface and normal ensembles for surface reconstruction 总被引:1,自引:0,他引:1
The majority of the existing techniques for surface reconstruction and the closely related problem of normal reconstruction are deterministic. Their main advantages are the speed and, given a reasonably good initial input, the high quality of the reconstructed surfaces. Nevertheless, their deterministic nature may hinder them from effectively handling incomplete data with noise and outliers. An ensemble is a statistical technique which can improve the performance of deterministic algorithms by putting them into a statistics based probabilistic setting. In this paper, we study the suitability of ensembles in normal and surface reconstruction. We experimented with a widely used normal reconstruction technique [Hoppe H, DeRose T, Duchamp T, McDonald J, Stuetzle W. Surface reconstruction from unorganized points. Computer Graphics 1992;71-8] and Multi-level Partitions of Unity implicits for surface reconstruction [Ohtake Y, Belyaev A, Alexa M, Turk G, Seidel H-P. Multi-level partition of unity implicits. ACM Transactions on Graphics 2003;22(3):463-70], showing that normal and surface ensembles can successfully be combined to handle noisy point sets. 相似文献
50.
Kyeong-Sik Shin Kyeong-Kap Paek Jung-Ho Park Tae-Song Kim Byeong-Kwon Ju Ji Yoon Kang 《Electron Device Letters, IEEE》2007,28(7):581-583
In this letter, we examined whether the parasitic bipolar junction transistors (BJTs) in the MOSFET fabricated by the standard CMOS process can play a role as a fluorescence detector. To suppress the action of two vertical parasitic BJTs, the gate and n-well were tied in the parasitic BJTs, and the body node was connected to the drain. The proposed device was compared with the inherent and the parasitic diodes in the MOSFET. It had 100 times higher photocurrents than the diodes in the MOSFET. In addition, it was applied for the detection of the fluorescent signal, and could detect near 10 nM of Alexa 546. Therefore, CMOS-process-compatible parasitic BJTs can be used as a photodetector in an integrated fluorescence detector. 相似文献