全文获取类型
收费全文 | 2128篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 323篇 |
金属工艺 | 41篇 |
机械仪表 | 40篇 |
建筑科学 | 81篇 |
矿业工程 | 15篇 |
能源动力 | 51篇 |
轻工业 | 187篇 |
水利工程 | 31篇 |
石油天然气 | 18篇 |
无线电 | 116篇 |
一般工业技术 | 248篇 |
冶金工业 | 568篇 |
原子能技术 | 12篇 |
自动化技术 | 399篇 |
出版年
2022年 | 12篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 13篇 |
2014年 | 28篇 |
2013年 | 106篇 |
2012年 | 54篇 |
2011年 | 72篇 |
2010年 | 59篇 |
2009年 | 56篇 |
2008年 | 76篇 |
2007年 | 78篇 |
2006年 | 87篇 |
2005年 | 78篇 |
2004年 | 80篇 |
2003年 | 68篇 |
2002年 | 59篇 |
2001年 | 55篇 |
2000年 | 40篇 |
1999年 | 31篇 |
1998年 | 43篇 |
1997年 | 51篇 |
1996年 | 59篇 |
1995年 | 51篇 |
1994年 | 34篇 |
1993年 | 61篇 |
1992年 | 64篇 |
1991年 | 32篇 |
1990年 | 38篇 |
1989年 | 55篇 |
1988年 | 40篇 |
1987年 | 49篇 |
1986年 | 32篇 |
1985年 | 34篇 |
1984年 | 54篇 |
1983年 | 41篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 24篇 |
1979年 | 24篇 |
1978年 | 28篇 |
1977年 | 21篇 |
1976年 | 18篇 |
1975年 | 22篇 |
1974年 | 29篇 |
1973年 | 17篇 |
1972年 | 11篇 |
1971年 | 12篇 |
排序方式: 共有2148条查询结果,搜索用时 0 毫秒
1.
Larry Gillard 《电子产品世界》2003,(14):31-32
从电力与精确数字、模拟信号,到高压气态和液态介质,如今的用户定制电缆几乎无所不传。线缆制造商们现在可以提供的连接线缆材料可谓五花八门,从多种规格的传统铜线和光纤,到各类软管和导管,甚至包括碳纤维等半导体材料。在对一种专用电缆的设计作出最终决定前,要做一点“外形匹配”的工作。通常要回答的问题包括:“要传输些什么?”、“有什么限制条件?”、“完成任务应该采用何种连接物”。在进行优化的阶段,还要另外考虑使用环境,包括可能存在的电磁干扰、机械应力影响(如扭曲和/或摩擦)、化学和/或高温的损伤。细绞合铜导线在进行大功率… 相似文献
2.
Barch Deanna M.; Mitropoulou Vivian; Harvey Philip D.; New Antonia S.; Silverman Jeremy M.; Siever Larry J. 《Canadian Metallurgical Quarterly》2004,113(4):556
Research suggests that schizotypal personality disorder (SPD) is a part of the spectrum of schizophrenia-related illnesses. This article hypothesizes that a deficit in the representation and maintenance of context is a core cognitive disturbance in schizophrenia and that SPD individuals should demonstrate context-processing deficits. To test this hypothesis, the authors administered 3 versions of their AX-CPT task, designed to assess context processing, to 35 healthy controls and 26 individuals with DSM-IV SPD. They also administered working memory and selective attention tasks. SPD individuals displayed context representation deficits similar to those found in schizophrenia but did not show the same additional deficits in context maintenance. Context processing was strongly associated with working memory and selective attention performance in the SPD individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
4.
Larry Bennett 《Journal of Urban Affairs》1987,9(3):263-276
ABSTRACT: In 1983 Chicago elected its first black mayor, Harold Washington. During Washington's first term of office, his administration not only reordered municipal priorities in such a fashion as to benefit his core, minority voting constituency, but also defined a municipal agenda emphasizing greater attention to neighborhood needs and more open government. In 1984 an important neighborhood coalition, the Save Our Neighborhoods/Save Our City Coalition (SON/SOC), proposed a linked development policy to tap downtown investment for neighborhood projects. Although SON/SOC's proposal was compatible with the Washington neighborhood agenda, this mainly white organization and the Washington administration experienced considerable difficulty in forging a mutually acceptable proposal The linked development debate in Chicago demonstrates the salience of race, class-cultural factors, and alternative approaches to neighborhood mobilization as barriers to the development of progressive coalitions in city politics. 相似文献
5.
The increasing complecity of many expert system application areas calls for the integration of the knowledge of multiple experts. The use of multiple experts introduces some interesting new problems during the process of knowledge acquisition. The problems are further complicated when the experts are geographically dispersed or unavailable for face-to-face interactions.
This article discusses the motivations for acquiring the knowledge of multiple experts, the problems related to knowledge acquisition, new issues that arise whens multiple experts interact, solutions that can be brought to bear in building multiple expert systems (particularly when experts are geographically dispersed), and new tools for knowledge engineers to use when dealing with multiple experts. 相似文献
6.
C Andrew Clayton Larry Michael Edo D Pellizzari James J Quackenboss 《Quality Assurance: Good Practice, Regulation, and Law》2003,10(3-4):161-175
Multimedia data from two probability-based exposure studies were investigated in terms of how missing data and measurement-error imprecision affected estimation of population parameters and associations. Missing data resulted mainly from individuals'refusing to participate in certain measurement activities, rather than from field or laboratory problems; it suggests that future studies should focus on methods for maximizing participation rates. Measurement error variances computed from duplicate-sample data were small relative to the inherent variation in the populations; consequently, adjustments in nonparametric percentile estimates to account for measurement imprecision were small. Methods of adjustment based on lognormality assumptions, however, appeared to perform poorly. 相似文献
7.
Larry MedskerEfraim Turban 《Expert systems with applications》1994,7(4):553-562
Expert (or knowledge-based) systems are used today either as stand-alone or in conjunction with other computer-based information systems (CBIS) in thousands of organizations worldwide to provide decision support for solving problems that traditional information systems were unable to solve. Neural computing is an emerging promising technology with few successful applications. By integrating the two technologies one can achieve some improvements in the implementation of each as well as increase the scope of application. We provide a comprehensive framework and examples of such an integration. 相似文献
8.
Robert Hummel Larry M. Manevitz 《Annals of Mathematics and Artificial Intelligence》1997,20(1-4):69-109
There are many different methods for incorporating notions of uncertainty in evidential reasoning. A common component to these
methods is the use of additional values, other than conditional probabilities, to assert current degrees of belief and certainties
in propositions. Beginning with the viewpoint that these values can be associated with statistics of multiple opinions in
an evidential reasoning system, we categorize the choices that are available in updating and tracking these multiple opinions.
In this way, we develop a matrix of different uncertainty calculi, some of which are standard, and others are new. The main
contribution is to formalize a framework under which different methods for reasoning with uncertainty can be evaluated. As
examples, we see that both the “Kalman filtering” approach and the “Dempster–Shafer” approach to reasoning with uncertainty
can be interpreted within this framework of representing uncertainty by the statistics of multiple opinions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Bond Gary R.; Dietzen Laura L.; McGrew John H.; Miller Larry D. 《Canadian Metallurgical Quarterly》1995,40(2):75
Tested the hypothesis that Ss with severe mental illnesses would achieve better vocational outcomes with an accelerated approach to supported employment (AASE), as compared to gradual approaches (GA) with prevocational training. 86 Ss (mean age 35.1 yrs) with a diagnosis of a serious mental illness, were randomly assigned to either the AASE, or the GA, which included a minimum of 4 mo prevocational training. Data were obtained on indicators of vocational outcomes over 2 yrs, and for a limited number of Ss (n=36), during the 4th yr of inception into the program. Initially, only 5% of Ss preferred prevocational training. After 1 yr, AASE Ss showed better outcomes for a range of indicators, including achievement of competitive employment, duration of employment and mean earnings. During the 4th yr, 59% of these Ss were competitively employed, as compared to only 6% of GA Ss. Rehabilitation is more effective using AASE than GA. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.