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   200篇
  免费   11篇
电工技术   3篇
化学工业   44篇
金属工艺   4篇
机械仪表   1篇
建筑科学   7篇
矿业工程   1篇
能源动力   5篇
轻工业   32篇
水利工程   5篇
石油天然气   1篇
无线电   8篇
一般工业技术   32篇
冶金工业   42篇
原子能技术   2篇
自动化技术   24篇
  2023年   1篇
  2022年   9篇
  2021年   10篇
  2020年   7篇
  2019年   12篇
  2018年   9篇
  2017年   8篇
  2016年   4篇
  2015年   6篇
  2014年   5篇
  2013年   12篇
  2012年   14篇
  2011年   19篇
  2010年   16篇
  2009年   11篇
  2008年   17篇
  2007年   10篇
  2006年   11篇
  2005年   10篇
  2004年   7篇
  2003年   7篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
排序方式: 共有211条查询结果,搜索用时 15 毫秒
91.
This study constructively extends Arthur et al. (2001) by assessing the convergence of self-report and archival motor vehicle crash involvement and moving violations data in a 2-year longitudinal follow-up. The relationships among these criteria, conscientiousness, and driving speed were also assessed using both predictive and postdictive criterion-related validation designs. Data were collected from a 2-year follow-up sample of 334 participants. Results suggested a lack of convergence between self-report and archival data at both Time 1 and Time 2. In addition, the predictor/criterion relationships varied across research design and data source. An actual application of our findings is that the interpretation of relationships between specified predictors and crash involvement and moving violations must be made within the context of the criterion-related validation design and criterion data source. Specifically, predictive designs may produce results different from those of postdictive designs (which are more commonly used). Furthermore, self-report data appear to include a broader range of incidents (more crashes and tickets), and thus researchers should consider using self-report data when they are interested in including lower threshold crashes and tickets that may not be reported on state records (e.g., because of the completion of a defensive driving course).  相似文献   
92.
Metallurgical and Materials Transactions A - Eutectics serve as an interesting material class for fundamental research on solidification as well as holding promise for new, high-tech applications....  相似文献   
93.
Clinical lore abounds when discussing the issue of treating trauma-related symptoms in substance-dependent clients. Historically, clinicians have wondered whether they should wait until the client has gained substantial abstinence from abused substances before initiating trauma treatment or if trauma treatment should be conducted during substance use treatment. Furthermore, questions arise with regard to exactly how trauma-related symptoms should be addressed and how trauma treatment should be incorporated into the recovery process. In this article, the growing literature suggesting that posttraumatic stress disorder (PTSD) can be treated concurrently with substance use disorders is reviewed. In addition, the unique challenges of implementing treatment for PTSD with substance-dependent clients seeking treatment in a residential treatment facility are discussed. Specifically, we provide concrete suggestions about how to utilize prolonged exposure, a very effective treatment for PTSD, with clients in a residential substance use treatment facility, including use of the internet to facilitate exposure therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
The rate at which dietary α‐linolenic acid (ALA) is desaturated and elongated to its longer‐chain n‐3 polyunsaturated fatty acid (PUFA) in humans is not agreed upon. In this study, we applied a methodology developed using rodents to investigate the whole‐body, presumably hepatic, synthesis‐secretion rates of esterified n‐3 PUFA from circulating unesterified ALA in 2 healthy overweight women after 10 weeks of low‐linoleate diet exposure. During continuous iv infusion of d5‐ALA, 17 arterial blood samples were collected from each subject at ?10, 0, 10, 20, 40, 60, 80, 100, 120, 150, 180, and 210 min, and at 4, 5, 6, 7, and 8 h after beginning infusion. Plasma esterified d5‐n‐3 PUFA concentrations were plotted against the infusion time and fit to a sigmoidal curve using nonlinear regression. These curves were used to estimate kinetic parameters using a kinetic analysis developed using rodents. Calculated synthesis‐secretion rates of esterified eicosapentaenoate, n‐3 docosapentaenoate, docosahexaenoic acid, tetracosapentaenate, and tetracosahexaenoate from circulating unesterified ALA were 2.1 and 2.7; 1.7 and 5.3; 0.47 and 0.27; 0.30 and 0.30; and 0.32 and 0.27 mg/day for subjects S01 and S02, respectively. This study provides new estimates of whole‐body synthesis‐secretion rates of esterified longer‐chain n‐3 PUFA from circulating unesterified ALA in human subjects. This method now can be extended to study factors that regulate human whole‐body PUFA synthesis‐secretion in health and disease.  相似文献   
95.
Review of biodiesel composition, properties, and specifications   总被引:4,自引:0,他引:4  
Biodiesel is a renewable transportation fuel consisting of fatty acid methyl esters (FAME), generally produced by transesterification of vegetable oils and animal fats. In this review, the fatty acid (FA) profiles of 12 common biodiesel feedstocks were summarized. Considerable compositional variability exists across the range of feedstocks. For example, coconut, palm and tallow contain high amounts of saturated FA; while corn, rapeseed, safflower, soy, and sunflower are dominated by unsaturated FA. Much less information is available regarding the FA profiles of algal lipids that could serve as biodiesel feedstocks. However, some algal species contain considerably higher levels of poly-unsaturated FA than is typically found in vegetable oils.Differences in chemical and physical properties among biodiesel fuels can be explained largely by the fuels’ FA profiles. Two features that are especially influential are the size distribution and the degree of unsaturation within the FA structures. For the 12 biodiesel types reviewed here, it was shown that several fuel properties - including viscosity, specific gravity, cetane number, iodine value, and low temperature performance metrics - are highly correlated with the average unsaturation of the FAME profiles. Due to opposing effects of certain FAME structural features, it is not possible to define a single composition that is optimum with respect to all important fuel properties. However, to ensure satisfactory in-use performance with respect to low temperature operability and oxidative stability, biodiesel should contain relatively low concentrations of both long-chain saturated FAME and poly-unsaturated FAME.  相似文献   
96.
Delineation of tumor margins is a critical and challenging objective during brain cancer surgery. A tumor-targeting deep-blue nanoparticle-based visible contrast agent is described, which, for the first time, offers in vivo tumor-specific visible color staining. This technology thus enables color-guided tumor resection in real time, with no need for extra equipment or special lighting conditions. The visual contrast agent consists of polyacrylamide nanoparticles covalently linked to Coomassie Blue molecules (for nonleachable blue color contrast), which are surface-conjugated with polyethylene glycol and F3 peptides for efficient in vivo circulation and tumor targeting, respectively.  相似文献   
97.
98.
The State of Paraiba in Northeastern Brazil ranks as the fourth poorest state in the country. The objectives of this study are to conduct the psychometric validation of the Brazilian Household Food Insecurity Scale (EBIA), to assess the household food insecurity (HFI) prevalence, and to identify the association between HFI, poverty and dietary intake in a representative sample of Paraiba’s 14 poorest municipalities (N = 4533). All municipalities included had fewer than 50,000 inhabitants. EBIA had strong internal consistency (Cronbach’s alpha = 0.93 and 0.90 in households with and without children, respectively). The percentage of affirmative responses for each item was inversely associated with household income and the item curves were parallel across socio-economic strata. Rasch modeling indicated that: a) scale items severities followed theoretical expectations, b) all items had an adequate fit to the scale confirming its unidimensionality, and c) items ‘functioned’ similarly across key subpopulation characteristics including: urban/rural; men/women; younger/older; poor/less poor; Bolsa Familia enrollment (yes/no). HFI prevalence was higher in rural than in urban areas (55.5 % vs. 49.9 %, p < 0.0005) and severe food insecurity was substantially higher in rural areas (14.0 % vs. 9.0 %, p < 0.0005). HFI severity was inversely associated with household income, positively associated with daily sugar consumption and inversely associated with daily consumption of bread and nutrient dense foods (fruits, vegetables, and dairy). In conclusion, EBIA had strong internal and external validity at the municipal level. Findings are particularly relevant for Brazil where 89.1 % of municipalities (4,957 out of 5,565 municipalities) have less than 50,000 inhabitants.  相似文献   
99.
100.
Romantic relationships among young adults are rich with ambiguity and without a clear, universal progression emphasizing the need for active decision making. Lack of active decision making in romantic relationships can lead to increases in constraints (e.g. pregnancy, shared living space or finances) that promote the continuation of relationships that would have otherwise ended, leading to increased risk of relationship distress. Because there is no available assessment of thoughtfulness regarding relationship decisions, the authors of the present studies report data on the development of one such scale, the Relationship Deciding Scale (RDS). Study 1 (N = 995) reveals the factor structure of the RDS and provides reliability data for the emergent subscales. In Study 2 (N = 963), the obtained three-factor structure (Relationship Confidence, Knowledge of Warning Signs, and Deciding) is tested via confirmatory factor analysis, demonstrates convergent and discriminant validity, and is shown to predict relationship characteristics 14 weeks later. Study 3 (N = 805) shows the sensitivity of the three factors to change through examination of the influence of a semester-long intervention targeted at increasing decision making in relationships. Use of this scale for identifying and intervening with couples or individuals who lack active decision making in relationships may decrease their risk for future relationship distress. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  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