全文获取类型
收费全文 | 1020篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 137篇 |
金属工艺 | 27篇 |
机械仪表 | 23篇 |
建筑科学 | 36篇 |
矿业工程 | 8篇 |
能源动力 | 15篇 |
轻工业 | 114篇 |
水利工程 | 10篇 |
无线电 | 54篇 |
一般工业技术 | 144篇 |
冶金工业 | 335篇 |
原子能技术 | 8篇 |
自动化技术 | 128篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 31篇 |
2020年 | 21篇 |
2019年 | 13篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 29篇 |
2015年 | 20篇 |
2014年 | 35篇 |
2013年 | 50篇 |
2012年 | 39篇 |
2011年 | 47篇 |
2010年 | 20篇 |
2009年 | 38篇 |
2008年 | 54篇 |
2007年 | 51篇 |
2006年 | 31篇 |
2005年 | 28篇 |
2004年 | 25篇 |
2003年 | 22篇 |
2002年 | 17篇 |
2001年 | 23篇 |
2000年 | 25篇 |
1999年 | 23篇 |
1998年 | 54篇 |
1997年 | 46篇 |
1996年 | 25篇 |
1995年 | 27篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 5篇 |
排序方式: 共有1057条查询结果,搜索用时 15 毫秒
81.
82.
Allison Chang Cynthia Rudin Michael Cavaretta Robert Thomas Gloria Chou 《Machine Learning》2012,88(3):369-398
A good or bad product quality rating can make or break an organization. However, the notion of ??quality?? is often defined by an independent rating company that does not make the formula for determining the rank of a product publicly available. In order to invest wisely in product development, organizations are starting to use intelligent approaches for determining how funding for product development should be allocated. A critical step in this process is to ??reverse-engineer?? a rating company??s proprietary model as closely as possible. In this work, we provide a machine learning approach for this task, which optimizes a certain rank statistic that encodes preference information specific to quality rating data. We present experiments on data from a major quality rating company, and provide new methods for evaluating the solution. In addition, we provide an approach to use the reverse-engineered model to achieve a top ranked product in a cost-effective way. 相似文献
83.
We describe simple heuristics, based on perceptual variables, that produce human-like trajectories towards moving and stationary targets, and around moving and stationary obstacles. Interception of moving and stationary objects can be achieved through regulation of self-movement to maintain a target at a constant eccentricity, or by cancelling the change (drift) in the eccentricity of the target. We first show how a constant eccentricity strategy can be extended to home in on optimal paths and avoid obstacles. We then identify a simple visual speed ratio that signals a future collision, and the change in path needed for avoidance. The combination of heuristics based on eccentricity and the speed-ratio produces human-like behaviour. The heuristics can be used to animate avatars in virtual environments or to guide mobile robots. Combined with higher-level goal setting and way-finding behaviours, such navigation heuristics could provide the foundation for generative models of natural human locomotion. 相似文献
84.
Bielak Allison A. M.; Hultsch David F.; Strauss Esther; MacDonald Stuart W. S.; Hunter Michael A. 《Canadian Metallurgical Quarterly》2010,25(3):575
In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
M. T. Allison P. Daly 《International Journal of Satellite Communications and Networking》1986,4(1):19-33
Late in 1988 the Navstar GPS satellite navigation operational phase is planned to commence, offering world-wide, continuous and precise position-fixing and timing information to observers on land, sea, air and in space. This paper describes the development of a particular type of Navstar receiver—a single-channel, single-frequency, sequencing C/A code unit—and results of various tests carried out on the present phase-II satellite constellation. Part I of the paper deals essentially with the NAVSTAR satellite system and receiver hardware implementation, whereas Part II concentrates on receiver software and system performance. 相似文献
86.
McHale James P.; Kuersten-Hogan Regina; Lauretti Allison; Rasmussen Jeffrey L. 《Canadian Metallurgical Quarterly》2000,14(2):220
Fifty-two married partners played with their 30-mo-olds in both dyadic (parent–child) and whole family contexts and reported on their own coparenting activities (family integrity-promoting behavior, conflict, disparagement, and reprimand). Coparenting behavior observed in the whole family context was evaluated for antagonism, warmth and cooperation, child–adult centeredness, balance of positive involvement, and management of toddler behavior. Parallel balance and management scores were also formed using dyadic session data. Men's reported family integrity-promoting activities and women's reported conflict and reprimand activities were reliable correlates of family group process in both bivariate and discriminant analyses, with links enduring even after controlling for marital quality. Whole family- and dyad-based estimates of coparenting were altogether unrelated, and reported coparenting was tied only to behavior in family context, not to family measures created from dyad-based data. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
Goodyear Rodney K.; Newcomb Michael D.; Allison Russell D. 《Canadian Metallurgical Quarterly》2000,47(1):116
In addressing teen pregnancy, researchers have given scant attention either to the male partners or to psychological variables that might affect incidence rates. This study examined the contribution of developmental and psychosocial factors to the number of teen pregnancies for which young Latino men had been responsible. Data from a community sample of 307 Latino men were used to test a mediated model that incorporated 5 classes of variables: (a) developmental, family-of-origin variables, including indicators of quality of childhood experience; (b) gender-related attitudes and emotionality, including masculine ideology and alexithymia; (c) dating characteristics; (d) sexual behavior; and (e) the number of teen pregnancies for which a Latino man had been responsible. Results indicated that men's involvement in teen pregnancy was mediated not only by sexual activity, but that it was also affected by both developmental factors and gender-related attitudes and emotionality. Implications for teen pregnancy prevention, intervention, and research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
88.
Goff Phillip Atiba; Eberhardt Jennifer L.; Williams Melissa J.; Jackson Matthew Christian 《Canadian Metallurgical Quarterly》2008,94(2):292
Historical representations explicitly depicting Blacks as apelike have largely disappeared in the United States, yet a mental association between Blacks and apes remains. Here, the authors demonstrate that U.S. citizens implicitly associate Blacks and apes. In a series of laboratory studies, the authors reveal how this association influences study participants' basic cognitive processes and significantly alters their judgments in criminal justice contexts. Specifically, this Black-ape association alters visual perception and attention, and it increases endorsement of violence against Black suspects. In an archival study of actual criminal cases, the authors show that news articles written about Blacks who are convicted of capital crimes are more likely to contain ape-relevant language than news articles written about White convicts. Moreover, those who are implicitly portrayed as more apelike in these articles are more likely to be executed by the state than those who are not. The authors argue that examining the subtle persistence of specific historical representations such as these may not only enhance contemporary research on dehumanization, stereotyping, and implicit processes but also highlight common forms of discrimination that previously have gone unrecognized. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.
N. Chawla U. Habel Y. -L. Shen C. Andres J. W. Jones J. E. Allison 《Metallurgical and Materials Transactions A》2000,31(2):531-540
The effect of matrix microstructure on the stress-controlled fatigue behavior of a 2080 Al alloy reinforced with 30 pct SiC
particles was investigated. A thermomechanical heat treatment (T8) produced a fine and homogeneous distribution of S′ precipitates,
while a thermal heat treatment (T6) resulted in coarser and inhomogeneously distributed S′ precipitates. The cyclic and monotonic
strength, as well as the cyclic stress-strain response, were found to be significantly affected by the microstructure of the
matrix. Because of the finer and more-closely spaced precipitates, the composite given the T8 treatment exhibited higher yield
strengths than the T6 materials. Despite its lower yield strength, the T6 matrix composite exhibited higher fatigue resistance
than the T8 matrix composite. The cyclic deformation behavior of the composites is compared to monotonic deformation behavior
and is explained in terms of microstructural instabilities that cause cyclic hardening or softening. The effect of precipitate
spacing and size has a significant effect on fatigue behavior and is discussed. The interactive role of matrix strength and
SiC reinforcement on stress within “rogue” inclusions was quantified using a finite-element analysis (FEA) unit-cell model. 相似文献