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   510篇
  免费   55篇
  国内免费   6篇
电工技术   4篇
综合类   18篇
化学工业   104篇
金属工艺   3篇
机械仪表   5篇
建筑科学   23篇
能源动力   3篇
轻工业   293篇
水利工程   2篇
石油天然气   3篇
武器工业   1篇
无线电   33篇
一般工业技术   39篇
原子能技术   2篇
自动化技术   38篇
  2024年   5篇
  2023年   11篇
  2022年   20篇
  2021年   24篇
  2020年   22篇
  2019年   23篇
  2018年   20篇
  2017年   21篇
  2016年   22篇
  2015年   24篇
  2014年   21篇
  2013年   17篇
  2012年   16篇
  2011年   31篇
  2010年   33篇
  2009年   23篇
  2008年   18篇
  2007年   28篇
  2006年   30篇
  2005年   35篇
  2004年   23篇
  2003年   15篇
  2002年   16篇
  2001年   11篇
  2000年   16篇
  1999年   7篇
  1998年   8篇
  1997年   2篇
  1996年   8篇
  1995年   3篇
  1994年   5篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
  1985年   1篇
  1984年   1篇
  1982年   3篇
排序方式: 共有571条查询结果,搜索用时 500 毫秒
1.
This study presents systematic packaging design tools integrating functional and environmental consequences on product life cycle. To design packaging for sustainability, the trade-offs between functional and environmental aspects of packaging throughout the product life cycle should be considered. However, it is difficult for packaging designers to understand the overall trade-offs because the extent of the design consequences on the entire life cycle of packaging and its contents is unclear. We developed two tools for packaging design: the Life Cycle Association Matrix (LCAM) and the Function Network Diagram (FND). The following three steps, based on literature reviews and interviews with industrial experts, were applied. Firstly, we listed the product functions and design variables related to the functions as the attributes allocated to the product life cycle. Secondly, the attributes were connected appropriately based on causal relationships. Lastly, we identified the factors to support decision making in the packaging design procedure. As a result, the LCAM depicts the design consequences on the life cycle, and the FND determines the stakeholders affected by the design consequences. Two case studies were demonstrated to analyze the trade-offs by using our tools. In the case studies, a liquid laundry detergent bottle and a milk carton were redesigned. The tools identified the design consequences and stakeholders affected by the redesign of the usability and protective function for the detergent and milk cases, respectively. The results showed the significance of understanding the design consequences on the product life cycle by integrating the functional and environmental aspects.  相似文献   
2.
In this work, the reactions of ethane and ethene in an oxidizing and non-oxidizing atmosphere over γ-alumina were investigated under temperature-programmed conditions, in an attempt to estimate the possible contribution and functionality of the support in the reaction pathway of ethane ODH over MoO3/Al2O3 catalysts. The results indicate that alumina contributes to the primary deep oxidation and dehydrogenation routes of ethane to COx and coke respectively, which proceed effectively over the acidic OH groups and the Al3+–O2− acidic centers. On the contrary, the formation of ethylene seems to be coupled to the presence of redox sites on the catalytic surface and requires the presence of the molybdena phase. Moreover, the redox sites of the MoOx species were found to unselectively activate the further overoxidation of the olefin to carbon oxides. Therefore, Al2O3 catalyzes the unselective primary oxidation of ethane to carbon oxides, whereas the molybdena phase is involved in the selective oxidative dehydrogenation (ODH) of ethane to ethene and the secondary overoxidation of ethene to COx.  相似文献   
3.
The effect of porous structure and surface functionality on the mercury capacity of a fly ash carbon and its activated sample has been investigated. The samples were tested for mercury adsorption using a fixed‐bed with a simulated flue gas. The activated fly ash carbon sample has lower mercury capacity than its precursor fly ash carbon (0.23 vs. 1.85 mg/g), although its surface area is around 15 times larger, 863 vs. 53 m2/g. It was found that oxygen functionality and the presence of halogen species on the surface of fly ash carbons may promote mercury adsorption, while the surface area does not seem to have a significant effect on their mercury capacity.  相似文献   
4.
功能性载溶菌酶微球的制备与性能   总被引:1,自引:0,他引:1  
刘源岗  周长忍 《化工进展》2007,26(12):1761-1766
为了制备理化性能优异的溶菌酶微球用于壳聚糖材料的体内降解调控,实验从多参数多指标出发,较为系统全面地考察了载溶菌酶微球的制备与性能。微球产率为5.7%~97.4%,粒径可控制在30~100μm,载药量和包封率理想。微球缓释效果明显,16 d的释放可控制在20%~70%的较大区间内,释放规律符合一级动力学模型。酶活基本保持完好,大部分在90%以上。  相似文献   
5.
Mixtures of an epoxy resin, hardener, and acid functionalized perfluoroether oligomers will readily undergo phase separation during curing. However, the conditions to bring about the growth of nuclei into microscopic particles have hitherto been found only for systems cured with anhydrides. In the present study perfluoroether oligomers were functionalized by established procedures to introduce both carboxylic acid groups and alkoxysilane groups in sites within the chain extended segments. The presence of alkoxysilane groups together with the prereaction step with an excess epoxy resin, prior to the addition of the aromatic amine hardener, induced phase separation by a nucleation‐and‐growth mechanism. The dual functionality in the perfluoroether oligomer was even more beneficial when the alkoxysilane groups were hydrolyzed prior to the addition of the amine hardener. Under such circumstances the precipitation of the perfluoroether oligomer occurred quantitatively, as indicated by the complete absence of any plasticization effects in the epoxy matrix. From electron microscopy examinations, thermal analysis, and measurements of mechanical properties it was possible to deduce a plausible mechanism for the formation of the typical core‐shell aggregates within the precipitated particles for these systems, which could also be applied to other systems, such as those using carboxylic‐acid‐terminated butadiene acrylonitrile oligomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1036–1049, 2005  相似文献   
6.
Micron‐sized polymer particles were coated with layers of nickel compounds by plating electrolessly in the presence of aqueous solutions of nickel chloride, sodium hypophosphite, sodium citrate, and ammonium chloride at elevated temperature. The uniform functional polymer particle could be obtained by seeded polymerization. To investigate the effect of surface functionality on the conditions for nickel deposition, the polymer particle was functionalized with the thiol group. From morphological observation, it was found that the mode of nickel deposition was greatly dependent on the surface functionality of the polymer particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 420–424, 2003  相似文献   
7.
针对嵌入式平台功耗低、资源少等特点,设计了适用于嵌入式平台的可信芯片及嵌入式软件栈,构建了嵌入式可信计算平台。为使嵌入式可信计算平台能够有效地为嵌入式应用提供可信功能支持,论文设计并实现了嵌入式可信计算平台测评系统,从应用服务角度出发,保证嵌入式应用调用的可信功能的正确性。该测评系统支持多个平台的并行测试,并能根据不同需求定制测试方案,支持测试报表分析测试结果,且引起的平台额外开销较小。  相似文献   
8.
为了调查目前市场上皮肤风衣面料的功能性和织物手感,选取6种市场上常见的皮肤风衣面料进行了对比实验.首先采用客观实验的方法对织物的防水性和防紫外线性进行对比分析,随后采用主观评价的方法对织物的柔软度和滑爽度进行评价,最后利用灰色近优综合评价法对织物的功能性和织物手感进行综合评价.研究发现,增加织物表面的光滑程度和进行防水整理均可提高织物的防水性;防紫外线整理在一定程度上可以改善织物的防紫外线性,但大多数皮肤风衣面料的防紫外线性均达不到国家标准要求;提高织物紧度使织物的柔软度有所下降;增大经纬紧度差值可以提高织物的滑爽度.  相似文献   
9.
白琳  叶丹  魏峻  黄涛 《软件学报》2015,26(8):1886-1906
服务因其灵活的应用机制,逐渐成为软件开发过程中的主要载体.面对网络中涌现出的大量功能相同或相似而QoS(quality of service)不同的服务群体,如何快速、准确地定位到所需要的服务个体,仍是一项十分具有挑战性的工作.基于服务对功能的封装特性,提出一种基于服务功能规约的服务选择方法,将功能相关的抽象服务规约为一个粒度更大的服务级的抽象服务;然后,针对规约后的大粒度抽象服务完成服务发现和组合优化的过程.由于规约操作能够有效减少参与服务组合优化的抽象服务的个数以及相应的候选服务的个数,从而使算法的执行效率得到有效提升.实验结果表明:该算法与传统的启发式算法相比执行效率更高,并且对服务组合规模及候选服务规模表现出更好的扩展性.  相似文献   
10.
Organic-inorganic hybrid perovskite solar cells (PSCs) with unique properties exhibit their powerful competitiveness in the photovoltaic field over the past few years. However, the challenges of stability for perovskite devices limit the commercialization and further development. The 2D/3D hybrid structures combine the superior efficiency of bulk perovskites and the superior stability of layered perovskites and gradually get hotspots of the photovoltaic field. In addition, there remains a lack of comprehensive understanding and systematic summary of the function of 2D perovskite attributed to the complex nature of 2D/3D structures. Here, the latest progress of 2D/3D hybrid structures and focus on the functionality of 2D phases in mixed structures and the underlying mechanism from the perspective of their different distributions in the perovskite layer is summarized. Then, the insight and vital factors for overall improvements in the stability of 2D/3D structures are thoroughly discussed. Finally, it is expected that this review will contribute to the present challenges and future research prospects in the photovoltaic industry.  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