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   103篇
  免费   2篇
电工技术   1篇
化学工业   23篇
机械仪表   1篇
建筑科学   12篇
能源动力   3篇
轻工业   8篇
无线电   12篇
一般工业技术   13篇
冶金工业   23篇
自动化技术   9篇
  2022年   1篇
  2021年   2篇
  2020年   4篇
  2019年   1篇
  2017年   3篇
  2015年   3篇
  2014年   2篇
  2013年   6篇
  2012年   2篇
  2011年   3篇
  2010年   4篇
  2009年   5篇
  2008年   5篇
  2007年   3篇
  2006年   7篇
  2005年   4篇
  2004年   2篇
  2002年   3篇
  2001年   4篇
  1999年   1篇
  1998年   6篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1991年   1篇
  1990年   1篇
  1988年   2篇
  1987年   1篇
  1985年   3篇
  1979年   1篇
  1977年   3篇
  1976年   5篇
  1975年   1篇
  1970年   1篇
  1969年   2篇
  1967年   1篇
  1957年   1篇
  1934年   1篇
  1930年   1篇
  1926年   2篇
排序方式: 共有105条查询结果,搜索用时 15 毫秒
11.
We present GUEB a static tool detecting Use after Free vulnerabilities on disassembled code. This tool has been evaluated on a real vulnerability in the ProFTPD application (CVE-2011-4130).  相似文献   
12.
The article formalizes and measures the impact of club size on the quality of the public good provided to its members. Under a general framework we describe various functional forms that allow either network or crowding effects. Mechanisms of provision are that of a political process in which both the demand and the supply sides are considered. Estimations use the whole set of French municipalities. The supply model performs better than the demand model in the case of small municipalities, while for large cities the demand model has higher explanatory power. In so far as impact of city size on the quality of club goods is concerned, crowding does appear, but it does so in different patterns. For small towns marginal congestion first decreases then increases with population. Marginal congestion is decreasing for cities of intermediate size. For larger cities no significant effects are observed. Received: 27 June 2000 / Accepted: 20 August 2001 RID="*" ID="*" We have received particularly helpful comments from the editor-in-chief and two anonymous referees. We also thank Danièle Moret-Bailly for her friendly computational assistance.  相似文献   
13.
The SAFIRA-project (remediation research in regionally contaminated aquifers) focuses on innovative in situ remediation technologies to treat complex groundwater contamination. For this purpose, a model site located in Bitterfeld, Germany, was selected. The site is heavily contaminated with aliphatic and aromatic chlorinated hydrocarbons. The goal of the project is to develop, test and optimize new technologies of reactive barriers under controlled in situ conditions in a pilot plant. In order to create the necessary basis for this model project, the hydrogeological and hydrogeochemical conditions at the selected field site were investigated and various technologies for the design of the in situ pilot plant were examinated. Small-scale laboratory studies and tests in a mobile test unit (scale 1 m) were carried out in order to test the technologies prior to their application in the field. The technologies now tested in the reactive columns at the pilot plant include physico-chemical, microbial and combined techniques.  相似文献   
14.
Quantification of different effects (nonlinearity, heating, thixotropy, and fatigue) occurring during fatigue tests on bituminous mixtures is presented in this paper. A focus is given on the nonlinearity phenomenon. Continuous fatigue tests and a test with specific protocol (called fatigue tests to estimate biasing effects) were performed in tension/compression mode on cylindrical samples of the same material. The analysis of results reveals that reversible effects (nonlinearity, heating, and thixotropy) are important (more than 90% decrease at 100,000 cycles for a strain amplitude of 100 μm/m at 10 Hz) and cannot be ignored when interpreting classical fatigue tests. The nonlinearity effects respect the time‐temperature superposition principle, and they are more pronounced at “high” temperature (at the same frequency). Direction of nonlinearity curve in the Cole‐Cole axes is shown to be independent of temperature and frequency for the considered range.  相似文献   
15.
Tin dioxide is emerging as an important material for use in copper indium gallium diselenide based solar cells. Amorphous tin dioxide may be used as a glass overlayer for covering the entire device and protecting it against water permeation. Tin dioxide is also a viable semiconductor candidate to replace the wide band gap zinc oxide window layer to improve the long-term device reliability. The film properties required by these two applications are different. Amorphous films have superior water permeation resistance while polycrystalline films generally have better charge carrier transport properties. Thus, it is important to understand how to tune the structure of tin dioxide films between amorphous and polycrystalline. Using X-ray diffraction (XRD) and Hall-effect measurements, we have studied the structure and electrical properties of tin dioxide films deposited by magnetron sputtering as a function of deposition temperature, sputtering power, feed gas composition and film thickness. Films deposited at room temperature are semicrystalline with nanometer size SnO2 crystals embedded in an amorphous matrix. Film crystallinity increases with deposition temperature. When the films are crystalline, the X-ray diffraction intensity pattern is different than that of the powder diffraction pattern indicating that the films are textured with (101) and (211) directions oriented parallel to the surface normal. This texturing is observed on a variety of substrates including soda-lime glass (SLG), Mo-coated soda-lime glass and (100) silicon. Addition of oxygen to the sputtering gas, argon, increases the crystallinity and changes the orientation of the tin dioxide grains: (110) XRD intensity increases relative to the (101) and (211) diffraction peaks and this effect is observed both on Mo-coated SLG and (100) silicon wafers. Films with resistivities ranging between 8 mΩ cm and 800 mΩ cm could be deposited. The films are n-type with carrier concentrations in the 3 × 1018 cm− 3 to 3 × 1020 cm− 3 range. Carrier concentration decreases when the oxygen concentration in the feed gas is above 5%. Electron mobilities range from 1 to 7 cm2/V s and increase with increasing film thickness, oxygen addition to the feed gas and film crystallinity. Electron mobilities in the 1-3 cm2/V s range can be obtained even in semicrystalline films. Initial deposition rates range from 4 nm/min at low sputtering power to 11 nm/min at higher powers. However, deposition rate decreases with deposition time by as much as 30%.  相似文献   
16.
Although thermal barrier coatings are used in industry for several decades there is still considerable demand for a further improvement of this coating system. Present research projects are for example dealing with the improvement of temperature capability and lifetime, developing of lifetime models, new processing technologies, or incorporating of additional functional properties in the coating. The present paper tries to give an overview on these recent research activities. In addition, it will also try to describe the different burner rig test facilities in Europe, which serve as an important test bed of thermal barrier coating systems.  相似文献   
17.
Amphibian populations appear to be declining around the world. Although there is no single cause, one factor may be pollution from heavy metals. As a result of mining in the Silver Valley of Idaho, heavy metals have been released into habitats containing many species of sensitive organisms, including spotted frogs (Rana luteiventris). While the gross extent of pollution has been well documented, the more subtle behavioral effects of heavy metals such as lead, zinc, and cadmium are less well studied. We tested the effects of heavy metals on the short-term survival (LC50) of spotted frog tadpoles. Compared to single metals, metals presented together were toxic at lower doses. We also raised the tadpoles in outdoor mini-ecosystems containing either a single heavy metal or soil from an EPA Superfund site in the Silver Valley known to be composed of numerous heavy metals. Exposure to Silver Valley soil resulted in delayed metamorphosis. We tested the ability of metal-exposed tadpoles to detect and respond to chemical cues emanating from predacious rainbow trout. We found that high levels of Silver Valley soil, medium levels of zinc, and medium and high levels of lead resulted in a decreased fright response. Low levels of cadmium, zinc, and lead did not cause a significant effect, but low levels of soil did result in a decreased fright response. Heavy metals may alter interactions between tadpoles and their predators.  相似文献   
18.
Although psychologists and lay people share a common belief that positive self-regard is associated directly with positive regard for others, the influence of parameters such as the nature of the others and their perceived similarity to the self rarely is considered. To investigate the influence of the degree of identification with the others who are rated on self–other correlations, we examined the relation of self-ratings to ratings of same- and opposite-sex others in 60 preadolescent boys and 69 preadolescent girls. Each subject rated himself or herself and 8–20 classmates on 7 personality variables. Favorable self-ratings and ratings of same- and opposite-sex others were significantly positively associated in both groups: Girls exhibited similar self–other relations when rating same- and opposite-sex others; boys identified more strongly with their sex roles than girls and exhibited a stronger relation between self- and other-ratings when the others were of the same sex. We concluded that a positive relation between self- and other-acceptance is fairly robust, but the magnitude of the relation is moderated by the degree of identification with those rated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
19.
    
Ohne Zusammenfassung  相似文献   
20.
This article reviews issues involved in the diagnosis of insomnia and discusses treatment options, including pharmacologic treatment, which is indicated mainly in acute insomnia. Sleep hygiene is then discussed. Finally, the various behavioral treatments are reviewed, including light therapy, relaxation training, cognitive therapy, sleep curtailment, and stimulus control therapy.  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