全文获取类型
收费全文 | 1345篇 |
免费 | 86篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 10篇 |
综合类 | 3篇 |
化学工业 | 382篇 |
金属工艺 | 22篇 |
机械仪表 | 19篇 |
建筑科学 | 72篇 |
能源动力 | 17篇 |
轻工业 | 210篇 |
水利工程 | 15篇 |
石油天然气 | 1篇 |
无线电 | 102篇 |
一般工业技术 | 220篇 |
冶金工业 | 196篇 |
原子能技术 | 10篇 |
自动化技术 | 155篇 |
出版年
2024年 | 2篇 |
2023年 | 22篇 |
2022年 | 51篇 |
2021年 | 87篇 |
2020年 | 53篇 |
2019年 | 33篇 |
2018年 | 44篇 |
2017年 | 36篇 |
2016年 | 44篇 |
2015年 | 48篇 |
2014年 | 44篇 |
2013年 | 82篇 |
2012年 | 101篇 |
2011年 | 101篇 |
2010年 | 75篇 |
2009年 | 81篇 |
2008年 | 104篇 |
2007年 | 68篇 |
2006年 | 49篇 |
2005年 | 41篇 |
2004年 | 35篇 |
2003年 | 36篇 |
2002年 | 24篇 |
2001年 | 24篇 |
2000年 | 12篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有1434条查询结果,搜索用时 15 毫秒
81.
Polyelectrolyte multilayer (PEM) transfer printing has been previously achieved by stamping under dry conditions. Here, we show for the first time, that PEM can be transferred from a stamp to the base substrate under aqueous conditions whereby the two surfaces are in a non-contact mode. Degradable multilayers of (PAA/PEG)(10.5) followed by non-degradable multilayers of (PDAC/SPS)(80.5) were fabricated under acidic pH conditions on either PDMS or glass (stamp), and subsequently transferred over top of another multilayer prepared on a different substrate (base substrate), with a spacing of ~ 200 μm between the stamping surface and the base substrate. This multilayer transfer was performed under physiological pH conditions. This process is referred to herein as non-contact, aqueous-phase multilayer (NAM) transfer. NAM transfer can be useful for applications such as fabricating three-dimensional (3-D) cellular scaffolds. We attempted to create a 3-D cellular scaffold using NAM transfer, and characterized the scaffolds with conventional and fluorescence microscopy. 相似文献
82.
Zacharias Frontistis Christina Brebou Danae Venieri Dionissios Mantzavinos Alexandros Katsaounis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(10):1233-1236
This work reports for the first time the removal of 17α‐ethynylestradiol (EE2), a synthetic estrogen hormone, from secondary treated effluents by electrochemical oxidation. Experiments were conducted in a single compartment reactor comprising a boron‐doped diamond (BDD) anode and a zirconium cathode. EE2, in the range 100–800 µg L?1, was spiked in the post‐chlorination effluent of a municipal treatment plant and oxidized at 0.9–2.6 mA cm?2 current density. Complete degradation of 100 µg L?1 EE2 was achieved in 7 min at 2.1 mA cm?2 and inherent conditions, while the addition of 0.1 mol L?1 NaCl achieved removal in just a few seconds. The process was then tested in the pre‐chlorination effluent at 2.1 mA cm?2 and inherent conditions; complete E. coli killing and EE2 removal occurred in just 1.5 and 3.5 min, respectively, while overall estrogenicity (assessed by the YES assay) and residual organic matter (in terms of chemical oxygen demand (COD)) decreased by 50% and 85% after 30 min, respectively. These results clearly show the potential of BBD electrochemical oxidation to serve as an efficient tertiary wastewater treatment. Copyright © 2011 Society of Chemical Industry 相似文献
83.
To illustrate the conditions under which successful innovation adoption takes place, this paper focuses on the implementation of information and communication technologies (ICT) through emerging communities in schools. Two types of such communities are described in terms of the degree of participation in the implementation: school-wide communities and enclaves. The article describes implementation practices in four primary schools with reported high ICT use, selected as case-studies. Four criteria, reflecting the domain, personnel relationships, policy and implementation goals and strategies, as well as staff consistency, are employed to outline the existence and types of communities of implementation within these schools. Findings indicate that, although both school-wide communities and enclaves are present in successful schools, enclaves – compared to school-wide communities – are related to lower levels of implementation. Based on these findings the authors discuss policy directions towards the development of school-wide communities as a purposeful implementation strategy to help transition ICT institutionalization from the initiation to the habitualization stage. 相似文献
84.
Gerard J. Puccio Roger L. Firestien Christina Coyle Cristina Masucci 《Creativity & Innovation Management》2006,15(1):19-33
A major focus within the field of creativity has been on the development of methodologies aimed at deliberately nurturing creative thinking. These methodologies have attempted to mirror the creative process in ways that allow individuals and groups to explicitly call on and employ their creative faculties. In an attempt to uplift employees’ creative capabilities many of these methodologies have been introduced into organizations through training programs, as well as through application to business challenges. Do these methods work? What is the empirical evidence that these deliberate creative process methods enhance employees’ creativity? Though there are a handful of creative process methods, few have married the concern for application with an interest in demonstrating the benefits of these applied efforts through systematic research. Creative Problem Solving (CPS), one of the more popular creative process models, has been one of the rare exceptions. The purpose of this paper is to synthesize the research literature that reports on the impact of CPS training carried out within organizational contexts, that is training programs that involved professionals or students working on real business challenges. Additionally, the positive benefits of CPS are further examined through reports that cite the outcomes of applying CPS to business challenges. In a field replete with methods that have been commercialized, it is imperative to strike a balance between research and practice as an imbalance towards practice may foster a field dominated by individuals who offer untested products and services. 相似文献
85.
Killen Joel D.; Fortmann Stephen P.; Murphy Greer M. Jr.; Hayward Chris; Arredondo Christina; Cromp DeAnn; Celio Maria; Abe Laurie; Wang Yun; Schatzberg Alan F. 《Canadian Metallurgical Quarterly》2006,74(2):286
The authors present results of a randomized clinical trial of the efficacy of extended treatment with bupropion SR in producing longer term cigarette smoking cessation. Adult smokers (N = 362) received open-label treatment (11 weeks) that combined relapse prevention training, bupropion SR, and nicotine patch followed by extended treatment (14 weeks) with bupropion SR or matching placebo. Abstinence percentages were relatively high (week 11: 52%; week 25: bupropion, 42%; placebo, 38%; week 52: bupropion, 33%; placebo, 34%), but bupropion SR did not surpass placebo. Gender and baseline craving level were identified as significant, independent moderators of treatment response. Men were more likely to abstain than women (week 11: 59% vs. 43%, p = .001; week 25: 48% vs. 31%, p = .001; week 52: 39% vs. 27%, p = .01). Because most smokers suffer relapse with any current cessation treatment, the comparatively high abstinence percentages achieved in this trial are of interest. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
87.
Shing Horng Lee Christina F. Jou Chien Ping Lee Cheng Chi Hu Jin Jei Wu 《Journal of Infrared, Millimeter and Terahertz Waves》1998,19(1):149-163
A frequency tunable active leaky-wave scanning antenna using Gunn-diode voltage control oscillator (VCO) as source is developed. The frequency tuning controlled by changing either the varactor diode dc bias or the Gunn diode dc bias is demonstrated. The measured scanning angle of active antenna is close to 15 degree as the Gunn VCO frequency tuned from 12.58GHz to 12.98GHz. To excite the first higher order mode of the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the middle line of the microstrip leaky wave antenna. This is a prototype of frequency scanning antenna using two terminal device, which can be easily scaled up to millimeter wave frequency region. 相似文献
88.
Summary The reaction of syndiotactic poly(methacrylic acid) with dicyclohexylcarbodiimide in the presence of benzylamine yields syndiotactic methacrylic acid-methacryloyl-N-benzylamide copolymers. A limiting conversion to amide of about 62% and a tendency of alternation for the monomer units is observed by1H-NMR. The amidation is accompanied by the formation of a smaller amount of cyclic imide as a side reaction. The imide portion can also be transformed into amide by a consecutive hydrolysis step. 相似文献
89.
Hariharan M Wowchuk C Nkansah P Gupta VK 《Drug development and industrial pharmacy》2004,30(6):565-572
This study discusses the effect of formulation composition on the physical characteristics and drug release behavior of controlled-release formulations made by roller compaction. The authors used mixture experimental design to study the effect of formulation components using diclofenac sodium as the model drug substance and varying relative amounts of microcrystalline cellulose (Avicel), hydroxypropyl methylcellulose (HPMC), and glyceryl behenate (Compritol). Dissolution studies revealed very little variability in drug release. The t70 values for the 13 formulations were found to vary between 260 and 550 min. A reduced cubic model was found to best fit the t70 data and gave an adjusted r-square of 0.9406. Each of the linear terms, the interaction terms between Compritol and Avicel and between all three of the tested factors were found to be significant. The longest release times were observed for formulations having higher concentrations of HPMC or Compritol. Tablets with higher concentrations of Avicel showed reduced ability to retard the release of the drug from the tablet matrix. Crushing strength showed systematic dependence on the formulation factors and could be modeled using a reduced quadratic model. The crushing strength values were highest at high concentrations of Avicel, while tablets with a high level of Compritol showed the lowest values. A predicted optimum formulation was derived by a numerical, multiresponse optimization technique. The validity of the model for predicting physical attributes of the product was also verified by experiment. The observed responses from the calculated optimum formulation were in very close agreement with values predicted by the model. The utility of a mixture experimental design for selecting formulation components of a roller compacted product was demonstrated. These simple statistical tools can allow a formulator to rationally select levels of various components in a formulation, improve the quality of products, and develop more robust processes. 相似文献
90.
Christina Svensson 《Journal of the American Oil Chemists' Society》1976,53(6):443-445
The tendency in the oil and fat industry in Europe as far as by-products and spent material are concerned is to use and regenerate
as much as possible for chemical-technical purposes. Materials with a high thermal value which are not suitable or profitable
for use in chemical-technical products will in the future probably be utilized as a fuel in combination with fuel oil. By-products
and spent material that cannot be exploited in the manners outlined above will be deposited in dumps. Incineration is another
possibility. However, the quantities of waste must be of a considerable magnitude if this method is not to be too expensive. 相似文献