全文获取类型
收费全文 | 697篇 |
免费 | 13篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 6篇 |
综合类 | 18篇 |
化学工业 | 375篇 |
金属工艺 | 18篇 |
机械仪表 | 15篇 |
建筑科学 | 59篇 |
矿业工程 | 13篇 |
能源动力 | 10篇 |
轻工业 | 64篇 |
水利工程 | 3篇 |
石油天然气 | 11篇 |
武器工业 | 4篇 |
无线电 | 18篇 |
一般工业技术 | 88篇 |
冶金工业 | 4篇 |
原子能技术 | 7篇 |
自动化技术 | 3篇 |
出版年
2023年 | 12篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 21篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 28篇 |
2013年 | 62篇 |
2012年 | 38篇 |
2011年 | 42篇 |
2010年 | 27篇 |
2009年 | 32篇 |
2008年 | 31篇 |
2007年 | 29篇 |
2006年 | 30篇 |
2005年 | 25篇 |
2004年 | 37篇 |
2003年 | 36篇 |
2002年 | 35篇 |
2001年 | 31篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 25篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 3篇 |
排序方式: 共有716条查询结果,搜索用时 31 毫秒
1.
Kai Liu Chenyang Zhou Jiaming Hu Song Zhang Qingqing Zhang Ce Sun Yusheng Shi Huajun Sun Changxia Yin Yuzhen Zhang Yu Fu 《Journal of the European Ceramic Society》2021,41(12):5909-5917
A digital light processing (DLP) technology has been developed for 3D printing lead-free barium titanate (BTO) piezoelectric ceramics. By comparing the curing and rheological properties of slurries with different photosensitive monomer, a high refractive index monomer acryloyl morpholine (ACMO) was chosen, and a design and preparation method of BTO slurry with high solid content, low viscosity and high curing ability was proposed. By further selecting the printing parameters, the single-layer exposure time was reduced and the forming efficiency has been greatly improved. Sintered specimens were obtained after a nitrogen-air double-step debinding and furnace sintering process, and the BTO ceramics fabricated with 80 wt% slurry shows the highest relative density (95.32 %) and piezoelectric constant (168.1 pC/N). Furthermore, complex-structured BTO ceramics were prepared, impregnated by epoxy resin and finally assembly made into hydrophones, which has significance for the future design and manufacture of piezoelectric ceramic-based composites that used in functional devices. 相似文献
2.
Cold-curing adhesives, characterized by an unsteady curing degree, present various advantages for assembling large scale structures set up under outdoor conditions. Thus various applications can be found in aerospace and automotive industries where structures are affected by thermal and mechanical loads. Hence, the curing state of the adhesive must be known to evaluate the lifetime of such bonded structures. The evolution of the polymerization of the adhesive Hysol EA-9321 during the curing process was examined in this paper. To that end, the curing degree of the adhesive was experimentally and analytically investigated for different curing cycles with a view to a potential application in the aerospace domain, where structures are assembled at low temperatures. Existing dynamic and isothermal curing models were applied to simulate the curing behavior of the adhesive. Then, an FEM model was developed to simulate the process of adhesive curing by taking into account a thermo-kinetic coupling. 相似文献
3.
4.
The primary purpose of this work is to review the literature about what is and is not known about using ethylene vinyl acetate (EVA0 copolymer as the encapsulant (or pottant) material in photovoltaic (PV) modules. Secondary purposes include elucidating the complexity of the encapsulation problem, providing an overview about encapsulation of PV cells and modules, providing a historical overview of the relevant research and development on EVA, summarizing performance losses reported for PV systems deployed since ca. 1981, and summarizing the general problems of polymer stability in a solar environment. We also provide a critical review of aspects of reported work for cases that we believe are important.Failure modes resolved in the early work to establish reliability of deployed modules and the purposes and properties of pottants, are summarized. Typical performance losses in large field-deployed, large-scale systems ranging from 1% to 10% per year are given quantitatively, and qualitative reports of EVA discoloration are summarized with respect to ultraviolet (UV), world-wide location and site dependence.The general stability of polymers and their desirable bulk properties for solar utilization are given. The stabilization formulation for EVA, its effectiveness, and changes in it during degradation are discussed. The degradation mechanisms for the base resin, e.g., unstabilized Elvax 150TM, and stabilized EVA are indicated for literature dating to the early 1950s, and the role played by unsaturated chromophores is indicated. The limited number of studies relating discoloration and PV cell efficiency are summarized.Observed degradation of EVA or the unstabilized base resin in the laboratory and examples used to measure the degradation are summarized in sections entitled: (1) thermally-induced degradation; (2) photodegradation and photothermal degradation of EVA in different temperature regimes; (3) photobleaching and photodegradation of the UV absorber and cross-linking agent; (4) acetic acid and metal and metal-oxide catalyzed oxidative degradation; and (5) discolaration and PV cell efficiency losses.Processing effects/influences on EVA stability are discussed in sections entitled: (1) EVA raw materials and extruded, uncured films; (2) thermal encapsulation processes; (3) effects of lamination, curing, and curing peroxide on gel content and chromophores formed; and (4) incomplete shielding of curing-generated chromophores. A summary is given for the limited number of accelerated lifetime testing efforts and examples of erroneous service lifetime predictions for EVA are discussed. The known factors that effect the discoloration rate of several EVA formulations are discussed in which the reduction in rate by using UV-absorbing superstrates is a prime example. A summary is given of what is and is not known about EVA degradation mechanisms, degradation from exposures in field-deployed modeules and/or laboratory testing, and factors that contribute to EVA stability or degradation. Finally, conclusions about using Elvax 150 in EVA formulations are summarized, and future prospects for developing the next-generation pottant for encapsulating PV modules are discussed. 相似文献
5.
N. JostJ. Karger-Kocsis 《Polymer》2002,43(4):1383-1389
Curing kinetics of a vinylester-urethane hybrid (VEUH) resin consisting of vinylester resin (VE) diluted in styrene and novolac type polyisocyanate (NPI) have been studied by differential scanning calorimetry (DSC). As VEUH is crosslinked via free radical polymerisation between the vinyl functions of styrene and VE, and polyaddition reaction between the secondary -OH groups of VE and -NCO of NPI, it was necessary to study these reactions separately. This was achieved by studying the curing with and without incorporating the NPI. The curing reaction was monitored by measuring the heat of reaction under isothermal and dynamic temperature conditions. Models describing the curing were developed, which are in good agreement with the experiments. A comparison between the curing of the VEUH and the VE resin without NPI leads to the conclusion that the curing of the VEUH as accessed by DSC is dominated by the radical polymerisation of styrene with VE although the two reactions are not time separated. 相似文献
6.
Ingo Alig Dirk Lellinger Harald Oehler Sergey A. Adamovsky Christoph Schick 《Progress in Organic Coatings》2008,61(2-4):166-175
A new microcalorimeter with eight parallel channels using robust, low cost sensors for characterization of coatings and adhesives is described and first experiments on coatings and adhesives are presented. The calorimetric sensors are based on thin glass plates (20 mm × 20 mm, thickness 150 μm) with heater and thermocouple sputtered on the surfaces (calorimetric active area of about 9 mm2). The setup allows heating and cooling experiments as well as isothermal measurements in the temperature-modulated mode with up to eight sensors in parallel. The measured quantities are the real (C′p) and imaginary part (C″p) of the complex heat capacity (), the related absolute value of the heat capacity () and the heat flow . An industrial computer (NI PXI system) with specific software for calibration and data recording controls the electronic components. Sensors can be embedded in a temperature controlled oven (heating and cooling by Peltier elements) or alternatively in a climatic cabinet with controlled temperature and humidity.
The method has been applied successfully to monitoring of film formation of aqueous polymer dispersions (styrene-acrylate copolymer) and curing of coatings. 相似文献
7.
介绍一种新型酚醛--丁腈并用耐高温高强度单组分浆状结构胶粘剂和组成比例以及固化条件对粘接强度的影响,该胶适用于粘接刹车制动蹄和飞机轻金属结构等。 相似文献
8.
9.
在确定了氯代四官能环氧/DDS树脂体系成型工艺的基础上,对浇注体的力学性能、复合材料的力学性能和耐热性进行了分析。结果表明,固化工艺为130℃/1h+150℃/2h+175℃/2h时,浇铸体具有较好的力学性能,高温力学性能保持率和较高的玻璃化温度tg和热分解温度,产品性能与国外同类产品相当。 相似文献
10.
研究了非等温过程中改性低毒脲醛树脂固化体系和未改性脲醛树脂固化体系的固化行为,并研究了不同固化剂施用量对改性树脂固化的影响,对不同树脂体系固化后的结构进行了表征。结果表明,改性的UF树脂固化后的交联度大于未改性树脂固化后的交联度。 相似文献