全文获取类型
收费全文 | 2508篇 |
免费 | 17篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 5篇 |
化学工业 | 114篇 |
金属工艺 | 16篇 |
机械仪表 | 13篇 |
建筑科学 | 31篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 59篇 |
水利工程 | 13篇 |
石油天然气 | 5篇 |
无线电 | 69篇 |
一般工业技术 | 115篇 |
冶金工业 | 1996篇 |
原子能技术 | 6篇 |
自动化技术 | 58篇 |
出版年
2023年 | 5篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 17篇 |
2011年 | 22篇 |
2010年 | 19篇 |
2009年 | 23篇 |
2008年 | 12篇 |
2007年 | 16篇 |
2006年 | 24篇 |
2005年 | 30篇 |
2004年 | 20篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 80篇 |
1998年 | 684篇 |
1997年 | 341篇 |
1996年 | 211篇 |
1995年 | 117篇 |
1994年 | 105篇 |
1993年 | 131篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 40篇 |
1989年 | 45篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 36篇 |
1985年 | 24篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 26篇 |
1980年 | 19篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 42篇 |
1976年 | 88篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有2527条查询结果,搜索用时 15 毫秒
71.
David Riley 《Accident; analysis and prevention》1987,19(6):449-462
The impact of drinking and driving is one focus of the mounting concern in the West over the widespread incidence of alcohol-related problems. Conventional wisdom, in the United Kingdom as well as in other countries, suggests that reducing average consumption levels will diminish the impact of the negative effects of alcohol including drinking and driving. But whether policies designed to achieve changes in per capita consumption by increasing alcohol taxes across the board constitute the most effective strategy to reduce drinking and driving is called into question. A number of competing interventions directed at the alcohol beverage industry are analysed and new directions for producers and policymakers are proposed. 相似文献
72.
Riley Hanus Matthias T. Agne Alexander J. E. Rettie Zhiwei Chen Gangjian Tan Duck Young Chung Mercouri G. Kanatzidis Yanzhong Pei Peter W. Voorhees G. Jeffrey Snyder 《Advanced materials (Deerfield Beach, Fla.)》2019,31(21)
The influence of micro/nanostructure on thermal conductivity is a topic of great scientific interest, particularly to thermoelectrics. The current understanding is that structural defects decrease thermal conductivity through phonon scattering where the phonon dispersion and speed of sound are assumed to remain constant. Experimental work on a PbTe model system is presented, which shows that the speed of sound linearly decreases with increased internal strain. This softening of the materials lattice completely accounts for the reduction in lattice thermal conductivity, without the introduction of additional phonon scattering mechanisms. Additionally, it is shown that a major contribution to the improvement in the thermoelectric figure of merit (zT > 2) of high‐efficiency Na‐doped PbTe can be attributed to lattice softening. While inhomogeneous internal strain fields are known to introduce phonon scattering centers, this study demonstrates that internal strain can modify phonon propagation speed as well. This presents new avenues to control lattice thermal conductivity, beyond phonon scattering. In practice, many engineering materials will exhibit both softening and scattering effects, as is shown in silicon. This work shines new light on studies of thermal conductivity in fields of energy materials, microelectronics, and nanoscale heat transfer. 相似文献
73.
High‐Quality,Ultraconformal Aluminum‐Doped Zinc Oxide Nanoplasmonic and Hyperbolic Metamaterials
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Conor T. Riley Joseph S. T. Smalley Kirk W. Post Dimitri N. Basov Yeshaiahu Fainman Deli Wang Zhaowei Liu Donald J. Sirbuly 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(7):892-901
Aluminum‐doped zinc oxide (AZO) is a tunable low‐loss plasmonic material capable of supporting dopant concentrations high enough to operate at telecommunication wavelengths. Due to its ultrahigh conformality and compatibility with semiconductor processing, atomic layer deposition (ALD) is a powerful tool for many plasmonic applications. However, despite many attempts, high‐quality AZO with a plasma frequency below 1550 nm has not yet been realized by ALD. Here a simple procedure is devised to tune the optical constants of AZO and enable plasmonic activity at 1550 nm with low loss. The highly conformal nature of ALD is also exploited to coat silicon nanopillars to create localized surface plasmon resonances that are tunable by adjusting the aluminum concentration, thermal conditions, and the use of a ZnO buffer layer. The high‐quality AZO is then used to make a layered AZO/ZnO structure that displays negative refraction in the telecommunication wavelength region due to hyperbolic dispersion. Finally, a novel synthetic scheme is demonstrated to create AZO embedded nanowires in ZnO, which also exhibits hyperbolic dispersion. 相似文献
74.
75.
76.
Kai Xu Pavel Hrma Jarrett A. Rice Michael J. Schweiger Brian J. Riley Nicole R. Overman Albert A. Kruger 《Journal of the American Ceramic Society》2016,99(9):2964-2970
The feed‐to‐glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold cap during nuclear waste vitrification. To investigate the conversion process, we analyzed heat‐treated samples of a simulated high‐level waste feed using X‐ray diffraction, electron probe microanalysis, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700°C before the emerging glass‐forming melt was completely connected. Above 700°C, intermediate aluminosilicate phases and quartz particles gradually dissolved in the continuous borosilicate melt, which expanded with transient foam. Knowledge of the chemistry and physics of feed‐to‐glass conversion will help us control the conversion path by changing the melter feed makeup to maximize the glass production rate. 相似文献
77.
Kevin Riley Anthony J. Devaney 《International journal of imaging systems and technology》1996,7(4):404-420
This article has as its goal the development and test and evaluation of wavelet-based algorithms for automatically detecting unknown anomalies in two-dimensional images. The general idea behind the work is that the class of wavelet transforms induces a so-called multiresolution analysis (MRA) in image space whereby the image of interest is naturally decomposed into a sequence of images of varying resolution (from coarse to fine resolution) in a computationally efficient manner. The anomaly detection can then be performed sequentially beginning at a coarse scale (low resolution) and proceeding to finer scales as needed. The wavelet representation thus effectively allows the user to zoom in on particular areas of interest and thus detect image anomalies in a very efficient manner. The article includes results from computer simulations testing the proposed approach against a standard energy-detection algorithm for the unknown anomalies embedded in additive Gaussian white noise. © 1996 John Wiley & Sons, Inc. 相似文献
78.
Fred J. Eller Robert J. Bartelt Baruch S. Shasha David J. Schuster David G. Riley Philip A. Stansly Thomas F. Mueller Kenneth D. Shuler Bruce Johnson James H. Davis Carol A. Sutherland 《Journal of chemical ecology》1994,20(7):1537-1555
This study describes the identification of an aggregation pheromone for the pepper weevil,Anthonomus eugenii and field trials of a synthetic pheromone blend. Volatile collections and gas chromatography revealed the presence of six male-specific compounds. These compounds were identified using chromatographic and spectral techniques as: (Z)-2-(3,3-dimethylcyclohexylidene)ethanol, (E)-2-(3,3-dimethylcyclohexylidene)ethanol, (Z)-(3,3-dimethylcyclohexylidene)acetaldehyde, (E)-(3,3-dimethylcyclohexylidene)acetaldehyde, (E)-3,7-dimethyl-2,6-octadienoic acid (geranic acid), and (E)-3,7-dimethyl-2,6-octadien-1-ol (geraniol). The emission rates of these compounds from feeding males were determined to be about: 7.2, 4.8, 0.45, 0.30, 2.0, and 0.30µg/male/day, respectively. Sticky traps baited with a synthetic blend of these compounds captured more pepper weevils (both sexes) than did unbaited control traps or pheromone-baited boll weevil traps. Commercial and laboratory formulations of the synthetic pheromone were both attractive. However, the commercial formulation did not release geranic acid properly, and geranic acid is necessary for full activity. The pheromones of the pepper weevil and the boll weevil are compared. Improvements for increasing trap efficiency and possible uses for the pepper weevil pheromone are discussed. A convenient method for purifying geranic acid is also described.The mention of firm names or trade products does not imply endorsement or recommendation by the U.S. Department of Agriculture over other firms or similar products not mentioned. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status or handicap. 相似文献
79.
W.KJ 《军民两用技术与产品》2014,(8):4-4
6月6日,中央全面深化改革领导小组第三次会议召开,会议审议通过了“关于设立知识产权法院的方案》等方案。 相似文献
80.