全文获取类型
收费全文 | 1385篇 |
免费 | 67篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 292篇 |
金属工艺 | 12篇 |
机械仪表 | 17篇 |
建筑科学 | 104篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 193篇 |
水利工程 | 14篇 |
石油天然气 | 7篇 |
无线电 | 82篇 |
一般工业技术 | 234篇 |
冶金工业 | 281篇 |
原子能技术 | 1篇 |
自动化技术 | 195篇 |
出版年
2023年 | 18篇 |
2022年 | 39篇 |
2021年 | 59篇 |
2020年 | 30篇 |
2019年 | 51篇 |
2018年 | 29篇 |
2017年 | 44篇 |
2016年 | 53篇 |
2015年 | 46篇 |
2014年 | 54篇 |
2013年 | 107篇 |
2012年 | 67篇 |
2011年 | 110篇 |
2010年 | 90篇 |
2009年 | 76篇 |
2008年 | 97篇 |
2007年 | 64篇 |
2006年 | 55篇 |
2005年 | 50篇 |
2004年 | 38篇 |
2003年 | 45篇 |
2002年 | 38篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1966年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有1454条查询结果,搜索用时 10 毫秒
61.
62.
Moskowitz D. S.; Russell Jennifer J.; Sadikaj Gentiana; Sutton Rachel 《Canadian Metallurgical Quarterly》2009,50(3):131
An overview is provided of measures that are administered repeatedly in daily life. Variations of this methodology have been referred to as ecological momentary assessment, diary methods, daily process measures, and most broadly as intensive repeated measures in naturalistic settings (IRM-NS). Contrasts are drawn between IRM-NS methods on the basis of different sampling strategies, such as time-contingent recording, signal-contingent recording, and event-contingent recording. Common threats to the internal validity, construct validity, and external validity of IRM-NS measures are reviewed, along with ways to reduce these threats. The statistical analysis of IRM-NS data is considered, with a particular focus on the investigation of intraindividual variability. An extended example is provided of an IRM-NS measure, an event-contingent recording method for the assessment of interpersonal behaviour. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
64.
Geological Process Models (GPMs) have been used in the past to simulate the distinctive stratigraphies formed in carbonate sediments, and to explore the interaction of controls that produce heterogeneity. Previous GPMs have only indirectly included the supersaturation of calcium carbonate in seawater, a key physicochemical control on carbonate production in reef and lagoon environments, by modifying production rates based on the distance from open marine sources. We here use the residence time of water in the lagoon and reef areas as a proxy for the supersaturation state of carbonate in a new process model, Carbonate GPM. Residence times in the model are calculated using a particle-tracking algorithm. Carbonate production is also controlled by water depth and wave power dissipation. Once deposited, sediment can be eroded, transported and re-deposited via both advective and diffusive processes. We show that using residence time as a control on production might explain the formation of non-ordered, three-dimensional carbonate stratigraphies by lateral shifts in the locus of carbonate deposition on timescales comparable to so-called 5th-order sea-level oscillations. We also show that representing supersaturation as a function of distance from open marine sources, as in previous models, cannot correctly predict the supersaturation distribution over a lagoon due to the intricacies of the flow regime. 相似文献
65.
This paper presents FROM, the fuzzy relational ontological model, a novel approach to encode knowledge for information retrieval applications based upon a fuzzy set framework that consider more generic concepts differently from specific terms. Besides the model itself, the paper also presents a retrieval algorithm that exploits FROM features through the application of fuzzy operations that uses this knowledge to extend a user's query based on these fuzzy associations. Experimental results have shown that retrieval with FROM presented better overall performance than other fuzzy‐based approaches for information retrieval. © 2009 Wiley Periodicals, Inc. 相似文献
66.
Hirshfeld-Becker Dina R.; Masek Bruce; Henin Aude; Blakely Lauren Raezer; Pollock-Wurman Rachel A.; McQuade Julia; DePetrillo Lillian; Briesch Jacquelyn; Ollendick Thomas H.; Rosenbaum Jerrold F.; Biederman Joseph 《Canadian Metallurgical Quarterly》2010,78(4):498
Objective: To examine the efficacy of a developmentally appropriate parent–child cognitive behavioral therapy (CBT) protocol for anxiety disorders in children ages 4–7 years. Method: Design: Randomized wait-list controlled trial. Conduct: Sixty-four children (53% female, mean age 5.4 years, 80% European American) with anxiety disorders were randomized to a parent–child CBT intervention (n = 34) or a 6-month wait-list condition (n = 30). Children were assessed by interviewers blind to treatment assignment, using structured diagnostic interviews with parents, laboratory assessments of behavioral inhibition, and parent questionnaires. Analysis: Chi-square analyses of outcome rates and linear and ordinal regression of repeated measures, examining time by intervention interactions. Results: The response rate (much or very much improved on the Clinical Global Impression Scale for Anxiety) among 57 completers was 69% versus 32% (CBT vs. controls), p 相似文献
67.
Bradley Jones Rachel T. Johnson 《Quality and Reliability Engineering International》2009,25(5):515-524
In an effort to speed the development of new products and processes, many companies are turning to computer simulations to avoid the time and expense of building prototypes. These computer simulations are often complex, taking hours to complete one run. If there are many variables affecting the results of the simulation, then it makes sense to design an experiment to gain the most information possible from a limited number of computer simulation runs. The researcher can use the results of these runs to build a surrogate model of the computer simulation model. The absence of noise is the key difference between computer simulation experiments and experiments in the real world. Since there is no variability in the results of computer experiments, optimal designs, which are based on reducing the variance of some statistic, have questionable utility. Replication, usually a ‘good thing’, is clearly undesirable in computer experiments. Thus, a new approach to experimentation is necessary. Published in 2009 by John Wiley & Sons, Ltd. 相似文献
68.
Genevieve M. Halpenny Rachel C. Steinhardt Krystle A. Okialda Pradip K. Mascharak 《Journal of materials science. Materials in medicine》2009,20(11):2353-2360
A light-activated NO donor, [Mn(PaPy3)(NO)]ClO4 (1a), has been incorporated into HEMA-based polymer hydrogel and the nitrosyl-polymer conjugate materials 1ax · HG and 1ax · HGMB have been characterized. The NO releasing properties and antibacterial capabilities of these materials in conjunction with
growth attenuators such as hydrogen peroxide and methylene blue (MB) are reported. Since the nitrosyl releases NO only upon
exposure to light, materials like 1ax · HGMB could be used as wound dressings that deliver NO under controlled conditions. 相似文献
69.
Rachel Ong Gavin A. Wood Siobhan Austen Therese Jefferson Marietta E.A. Haffner 《Housing Studies》2015,30(7):1158-1181
In an era of population ageing, the primary home is increasingly viewed as a personal resource that can perform a pension role in retirement. This article assesses the extent to which Australians aged 45 years and over withdraw housing equity through in situ mortgage equity withdrawal (MEW), downsizing and selling up. We find that the incidence of housing equity withdrawal has increased over the last decade despite a global financial crisis. MEW is the dominant form of equity release among those under pension age, while downsizing or selling up is more frequent among those above pension age. Downsizing and selling up are more likely to be prompted by adverse life events than MEW. Selling up is typically an option of last resort. Our findings offer insights into important debates around homeownership societies and the welfare role performed by owner-occupied housing in mid-to-late life. 相似文献
70.
Talley Amelia E.; Tomko Rachel L.; Littlefield Andrew K.; Trull Timothy J.; Sher Kenneth J. 《Canadian Metallurgical Quarterly》2011,25(3):530
Previous research has shown that sexual minority (i.e., nonheterosexual) individuals report increased problematic substance use involvement, compared with their sexual majority counterparts. We hypothesize that feelings of an unstable sense of self (i.e., identity disturbance) may potentially drive problematic substance use. The purpose of the current study is to examine identity disturbance among sexual minorities as a potential explanatory mechanism of increased sexual minority lifetime rates of substance dependence. Measures of identity disturbance and three indicators of sexual orientation from lifetime female (n = 16,629) and male (n = 13,553) alcohol/illicit drug users in Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were examined. Findings generally showed that the increased prevalence of alcohol dependence, illicit drug dependence, and combined alcohol/illicit drug dependence as well as a younger age of alcohol use initiation among sexual minority women was associated with elevated levels of identity disturbance. The results were consistent with a mediational role for identity disturbance in explaining the association between sexual minority status and substance dependence and were generally replicated among male sexual minority respondents. The current research suggests that identity disturbance, a predictor of substance use, may contribute to heightened risk for substance dependence among certain subgroups of sexual minority individuals. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献