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   126篇
  免费   1篇
化学工业   28篇
建筑科学   17篇
能源动力   1篇
轻工业   16篇
石油天然气   1篇
无线电   3篇
一般工业技术   6篇
冶金工业   36篇
自动化技术   19篇
  2022年   5篇
  2021年   4篇
  2019年   2篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2014年   1篇
  2013年   4篇
  2012年   3篇
  2011年   7篇
  2010年   4篇
  2009年   5篇
  2008年   8篇
  2007年   8篇
  2006年   10篇
  2005年   6篇
  2004年   3篇
  2003年   3篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   11篇
  1997年   2篇
  1996年   3篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1986年   1篇
  1985年   2篇
  1980年   3篇
  1979年   2篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1967年   1篇
  1931年   1篇
  1930年   1篇
  1901年   1篇
排序方式: 共有127条查询结果,搜索用时 15 毫秒
91.
When rats are forced to drink a morphine solution as their only source of fluid, they eventually reverse their initial preference and drink more morphine than water in a 2-bottle preference test. Two experiments with 13 male Holtzman rats examined the cause of this shift in preference using the taste reactivity test, which involves the analysis of fixed action patterns elicited by taste solutions infused into Ss' mouths. Three morphine concentrations (0.03, 0.6, and 1.5 mg/ml) and 2 levels of motivation (drug-replete and drug-withdrawal states) were studied. A greater percentage of ingestive taste reactivity responses occurred to the oral morphine infusion in morphine-raised than in water-raised Ss. Data are inconsistent with the idea that enhanced morphine ingestion is caused by anticipation of positive consequences. Instead, they support the idea that rats come to "like" the flavor of the morphine solution; in other words, the palatability evaluation of the morphine changes, possibly through an association between the flavor and the hedonically positive effects of the morphine. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
92.
93.
The authors examined the therapeutic alliance in evidence-based treatment for children (N = 185, 47 girls, 138 boys; ages 3-14 years) referred clinically for oppositional, aggressive, and antisocial behavior. Different alliances (child-therapist, parent-therapist) were assessed from each participant's perspective at 2 points over the course of treatment. As predicted, both child-therapist and parent-therapist alliances related to therapeutic change, family experience of barriers to participation in treatment, and treatment acceptability. Greater alliance was associated with greater therapeutic change, fewer perceived barriers, and greater treatment acceptability. The findings could not be attributed to the influence of socioeconomic disadvantage, parent psychopathology and stress, and child dysfunction or to rater effects (common rater variance in the predictors and criteria). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
A respiratory-defective mutant (C54) of Saccharomyces cerevisiae was found to have a phenotype consistent with a mutation in either mitochondrial protoporphyrinogen oxidase or ferrochelatase. The mutant is grossly deficient in hemes, accumulates protoporphyrin and is rescued by exogenous heme. The increased levels of protoporphyrin at the expense of heme is indicative of a block in one of the two last steps of the heme biosynthetic pathway. Complementation of C54 by a known ferrochelatase mutant suggested that the defect was most likely in HEM14 encoding protoporphyrinogen oxidase. A plasmid capable of complementing C54 was obtained by transformation with a yeast genomic plasmid library. A partial sequence of the insert identified the gene as reading frame YER014 of yeast chromosome V (GenBank Accession Number U18778). This reading frame codes for a protein homologous to human protoporphyrinogen oxidase. Disruption of this gene elicits a respiratory defect and accumulation of protoporphyrin. The phenotype of the null mutant together with the homology of YER014p to human protoporphyrinogen oxidase provide compelling evidence that YER014 is HEM14.  相似文献   
95.
In this study, the effects of long-term nitrogen deficiency (N 0.1 mM for 4 months) on growth, phenolic content and activity of phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were investigated in the leaves, inflorescences and roots of yarrow (Achillea collina Becker ex Rchb.) grown in hydroponics. The antioxidant capacity of methanol extracts was also evaluated. Nitrogen starvation decreased plant growth and the leaves’ total nitrogen, amino acids, proteins, chlorophylls and carotenoids contents indicating that the primary metabolism was severely limited by low nitrogen availability. The amount of total phenolics and the antioxidant capacity were higher in leaves and roots of nitrogen-starved compared to control plants. The most abundant phenolic acids identified in yarrow were 5-O-caffeoylquinic acid (chlorogenic acid), and 3,5 and 4,5-di-O-caffeoylquinic acids. Nitrogen starvation significantly increased the contents of all these compounds and the PAL activity in leaf and root tissues. Results suggest that hydroponics, with proper manipulation of nutritional factors, might be a suitable system for the production of compounds with health benefits, such as caffeic acid derivatives, in yarrow.  相似文献   
96.
Cement-based materials used to seal geothermal or deep oil wells are exposed to severe conditions. Optimizing engineering properties such as strength and permeability is therefore very important. We have synthesized hydroceramic materials for such applications based on the CaO−Al2O3−SiO2−H2O (CASH) system and cured them over a range of temperatures (200°–350°C). Depending on initial composition and curing temperature, hydroceramics of complex and diverse mineralogy and microstructure are formed. The minerals found include portlandite, jaffeite, xonotlite, gyrolite, 11 Å tobermorite, truscottite, hydrogarnet, and calcium aluminum silicate hydrate. These cement-based hydroceramic materials develop complicated pore structures, which strongly affect bulk properties. We report the compressive strength and permeability of these materials and show how these bulk engineering properties are related to microstructure. The compressive strength was found to be in the range 2–52 MPa and the intrinsic permeability in the range 0.5 × 10−17 to 3300 × 10−17 m2. Scanning electron microscopy (SEM) was used for imaging the hydroceramic microstructures. Further, we have computed the intrinsic permeability from 2-D SEM images by using the Stokes equation solver, Permsolver, applied to reconstructed 3-D images and the results are shown to be in good agreement with experimentally determined values.  相似文献   
97.
98.
99.
OBJECTIVE: We tested the hypotheses that (a) participants might develop motion sickness while playing "off-the-shelf" console video games and (b) postural motion would differ between sick and well participants, prior to the onset of motion sickness. BACKGROUND: There have been many anecdotal reports of motion sickness among people who play console video games (e.g., Xbox, PlayStation). METHOD: Participants (40 undergraduate students) played a game continuously for up to 50 min while standing or sitting. We varied the distance to the display screen (and, consequently, the visual angle of the display). RESULTS: Across conditions, the incidence of motion sickness ranged from 42% to 56%; incidence did not differ across conditions. During game play, head and torso motion differed between sick and well participants prior to the onset of subjective symptoms of motion sickness. CONCLUSION: The results indicate that console video games carry a significant risk of motion sickness. APPLICATION: Potential applications of this research include changes in the design of console video games and recommendations for how such systems should be used.  相似文献   
100.
Apart from being applied in production, Six Sigma has grown considerably in importance as a business process management (BPM) method in services. The transfer of the method from production to service applications does, however, pose problems which affect the success of implementing Six Sigma as a BPM method in services. For a successful application of the Six Sigma method in services it is helpful to know these possible problems in order to be able to avoid them and to achieve the goals of Six Sigma improvement projects. In addition from a theoretical view knowing the problems is a first step for further development of the Six Sigma method. Therefore, the present article deals with the following questions: which key problems regarding the application of Six Sigma in services are mentioned in the literature and which phases of the Six Sigma cycle can they be assigned to? The existing literature on this subject is reviewed and a qualitative content analysis of its contents is presented. Additionally, a survey based on the problems found in the literature is conducted to compare theory and practice. The evaluation of the results shows, on the one hand, that to date the problems of the application of Six Sigma in services have little been dealt with. On the other hand the evaluation provides a survey of the problems structured in accordance to the phases of the Six Sigma cycle. Thus, the present paper offers new findings as regards the state-of-the-art of the Six Sigma method.  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