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   95篇
  免费   8篇
  国内免费   1篇
化学工业   22篇
金属工艺   1篇
机械仪表   1篇
建筑科学   10篇
能源动力   1篇
轻工业   21篇
水利工程   1篇
无线电   7篇
一般工业技术   24篇
冶金工业   4篇
自动化技术   12篇
  2023年   3篇
  2021年   4篇
  2020年   6篇
  2019年   3篇
  2018年   3篇
  2017年   3篇
  2016年   9篇
  2015年   4篇
  2014年   2篇
  2013年   9篇
  2012年   4篇
  2011年   13篇
  2010年   7篇
  2009年   6篇
  2008年   7篇
  2007年   5篇
  2006年   2篇
  2005年   3篇
  2004年   3篇
  2003年   2篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
排序方式: 共有104条查询结果,搜索用时 15 毫秒
61.
The urea test strip was prepared using polyethyleneglycol based hydrogel, urease and commercial pH-indicator paper. The swelling behavior of hydrogel indicated the ability of the urea to penetrate into the matrix and allowing the test strip to respond in a short time. The color formed on the strip was distinguished by naked eyes in one minute at room temperature. The linear range for urea was 20–200?mg/dL. The assays have good reproducibility. Relative standard deviation values were found within the range of 3.37–12.95% and 1.68–9.54% for intra- and inter-day assays, respectively.  相似文献   
62.
Carvacrol is a known antioxidant molecule and commonly used in food and cosmetics as a flavor and fragrance agent; however, carvacrol has major issues such as high volatility, low water solubility, and stability. In this study, carvacrol/cyclodextrin inclusion complex fibers (carvacrol/CD-IC fibers) were produced via electrospinning in order to enhance thermal stability, water solubility and shelf-life of carvacrol having antioxidant activity. The phase solubility and computational modeling studies showed that carvacrol can form inclusion complexes with two types of modified CDs, hydroxypropyl-β-cyclodextrin (HPβCD) and hydroxypropyl-γ-cyclodextrin (HPγCD). The carvacrol/cyclodextrin inclusion complex electrospun fibers (carvacrol/HPβCD-IC fibers and carvacrol/HPγCD-IC fibers) were obtained as free-standing fibrous webs. Although pure carvacrol is highly volatile, the electrospun carvacrol/CD-IC fibers were quite effective to preserve high amount of carvacrol due to the inclusion complexation. In addition, carvacrol/CD-IC fibers have shown higher temperature stability for carvacrol. Moreover, carvacrol/CD-IC fibers showed more effective antioxidant activity as compared to pure carvacrol. The carvacrol/CD-IC fibrous webs have shown fast-dissolving character in water due to the enhanced water solubility of carvacrol/CD-IC and their ultrafine fiber structure. In short, encapsulation of carvacrol in electrospun CD-IC fibrous webs has shown potentials for food and oral care applications due to free-standing and fast-dissolving character along with high water solubility, high temperature stability and enhanced antioxidant by carvacrol/cyclodextrin inclusion complexation.  相似文献   
63.
64.
Polybrominated diphenyl ether (PBDE) concentrations of outdoor and indoor organic films on window glasses were measured at different locations (offices, laboratories, and homes in urban, suburban, rural, and industrial sites) in Izmir, Turkey. ∑(7)PBDE concentrations were dominated by technical penta and deca-BDE mixture components. Average total outdoor PBDE (∑(7)PBDE) concentrations for suburban, urban, and industrial sites were 43.5, 45.5, and 206 ng m(-2), respectively. This spatial gradient (industrial>urban>suburban concentrations) was similar to one observed for ambient air concentrations recently in Izmir, Turkey. The highest concentrations measured in the industrial area were attributed to the significant PBDE emissions from several steel plants located in the area. Air-organic film partitioning modeling results have suggested that organic films can be used in conjunction with the dynamic uptake model to approximate the gas-phase ambient air concentrations. Modeling results have also indicated that congeners in the gas-phase with very large octanol-air partition coefficients (i.e., BDE-154, -153, and -209) will require several months to approach equilibrium with the surface films. This finding may have important implications for gas-particle and gas-film partitioning, transport, and photolytic degradation of atmospheric PBDEs.  相似文献   
65.
66.
The main objectives of this paper are to evaluate the modeling effort associated with generating building information modeling (BIM) at different levels of detail (LoD) and the impact of LoD in a project in supporting mechanical, electrical and plumbing (MEP) design coordination. Results show an increase in total modeling time ranging from doubling the modeling effort to eleven folding it, when going from one LoD to another. When comparing modeling time per object, rates ranged from 0.2 (decreased modeling time) to 1.56 (increased modeling time). Based on the experiments done in MEP design coordination, it was observed that the automatic clash detection process using BIMs, with its consistently higher recall rate, provides a more complete identification of clashes, with the cost of false positives (low precision). This study showed that additional modeling effort can lead to more comprehensive analyses and better decision support during design and construction.  相似文献   
67.
Aim: The aim of this study was to evaluate the fracture strength of monolithic zirconia and fiber-reinforced composite (FRC) inlay-retained FPDs, both of which are cemented to the laser-etched cavity surfaces.

Materials and Methods: Eighty freshly extracted sound human teeth were used. A premolar and a molar tooth were embedded in an autopolymerizing acrylic resin. Forty acrylic resin models were randomly divided into two groups including monolithic zirconia and FRC inlay-retained FPDs (n = 20). Then, these groups were divided into two subgroups according to conditioning of the cavity surfaces with or without Er:YAG laser etching. Monolithic zirconia inlay-retained FPDs were produced by an inLab MC XL milling device using monolithic zirconia blocks. Tescera? Fiber Reinforcement Materials were used for the FRC inlay-retained FPDs. After 10.000 thermal cycles, fracture strength test was applied to the specimens.

Results: The monolithic zirconia inlay-retained FPDs exhibited the highest fracture strength than the FRC inlay-retained FPDs. Fracture strength was increased with laser etching for both restorative materials (p < 0.05).

Conclusion: Laser etching had positively effect on the fracture strength of the inlay-retained FDPs.  相似文献   
68.
The way adults express manner and path components of a motion event varies across typologically different languages both in speech and cospeech gestures, showing that language specificity in event encoding influences gesture. The authors tracked when and how this multimodal cross-linguistic variation develops in children learning Turkish and English, 2 typologically distinct languages. They found that children learn to speak in language-specific ways from age 3 onward (i.e., English speakers used 1 clause and Turkish speakers used 2 clauses to express manner and path). In contrast, English- and Turkish-speaking children's gestures looked similar at ages 3 and 5 (i.e., separate gestures for manner and path), differing from each other only at age 9 and in adulthood (i.e., English speakers used 1 gesture, but Turkish speakers used separate gestures for manner and path). The authors argue that this pattern of the development of cospeech gestures reflects a gradual shift to language-specific representations during speaking and shows that looking at speech alone may not be sufficient to understand the full process of language acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
69.
Mary E.  Janis P.  Dan  Karl R.  John  Asli  Jaeil 《Robotics and Computer》2007,23(6):727-734
This paper discusses the concepts associated with a new methodology, design for adaptation (DFAD), under development for achieving advanced sustainable designs. The DFAD methodology concept is based on the hypothesis that product life ends because a product is unable to adapt to change. A product may be retired for myriad reasons including that it is broken, out of style, or has become inefficient due to technology obsolescence. In these cases, the product was not able to adapt to change—it was unable to self-heal, it could not modify or reconfigure to meet changing fashion needs, or it could not be upgraded, for physical or economic reasons, to utilize new technology. To address these and similar issues, we are developing the DFAD methodology. DFAD is based on classical control theory and products are conceptualized and modeled as dynamic systems with feedback control strategies to respond, or adapt, effectively to changes in product performance criteria. The DFAD concept takes into account that changing performance requirements may be based on physical, cultural, environmental, and/or economic considerations, among others.  相似文献   
70.
The present study examined the out-of-school literacy activities of 70 students in 7th grade of prevocational training schools in the Netherlands. Guttmann’s Facet Theory was applied to study literacy as a complex, multifaceted phenomenon. With the increasing influence of digital technologies, the facet design approach was found especially suited to track the many changes occurring in presentation modalities, functions, and productive versus consumptive uses of literacy. The study shows that the facet approach was useful in pinpointing how these shifts in literacy engagement turn out differently for boys and girls. Based on self-reports via an Internet questionnaire, the study shows that girls outscored boys in every aspect of literacy, including computer and Internet based literacy practices. However, while among girls a more balanced profile was found regarding the engagement in traditional and new literacy practices, the boys reported a high preference for the new digital media. Moreover, we found that girls, compared to boys, used new literacy activities more often for educational purposes. The findings suggest that, given this more balanced profile, girls, compared to boys, are less at risk of losing touch with traditional print-based educational literacy in school.  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