全文获取类型
收费全文 | 2336篇 |
免费 | 104篇 |
国内免费 | 34篇 |
专业分类
电工技术 | 12篇 |
综合类 | 80篇 |
化学工业 | 1710篇 |
金属工艺 | 8篇 |
机械仪表 | 10篇 |
建筑科学 | 40篇 |
矿业工程 | 4篇 |
能源动力 | 8篇 |
轻工业 | 76篇 |
石油天然气 | 277篇 |
武器工业 | 1篇 |
无线电 | 10篇 |
一般工业技术 | 206篇 |
冶金工业 | 11篇 |
原子能技术 | 12篇 |
自动化技术 | 9篇 |
出版年
2024年 | 4篇 |
2023年 | 13篇 |
2022年 | 11篇 |
2021年 | 39篇 |
2020年 | 21篇 |
2019年 | 32篇 |
2018年 | 40篇 |
2017年 | 31篇 |
2016年 | 53篇 |
2015年 | 36篇 |
2014年 | 81篇 |
2013年 | 75篇 |
2012年 | 139篇 |
2011年 | 121篇 |
2010年 | 105篇 |
2009年 | 91篇 |
2008年 | 96篇 |
2007年 | 147篇 |
2006年 | 152篇 |
2005年 | 142篇 |
2004年 | 101篇 |
2003年 | 107篇 |
2002年 | 135篇 |
2001年 | 139篇 |
2000年 | 115篇 |
1999年 | 100篇 |
1998年 | 85篇 |
1997年 | 50篇 |
1996年 | 34篇 |
1995年 | 37篇 |
1994年 | 33篇 |
1993年 | 29篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 9篇 |
排序方式: 共有2474条查询结果,搜索用时 46 毫秒
101.
Research on Poly(Styrene-Crylicacid)-Suported Neodymium Complex Catalytic Copolymerization of Styrene and 4-Vinylpyridine 相似文献
102.
Marcia C. Delpech Ivana L. Mello Fernanda C. S. Delgado Jurandir M. Sousa 《应用聚合物科学杂志》2012,125(5):4074-4081
The extender oil usually employed in compositions of rubbers based on styrene and butadiene (SBR) 1712 is the distilled aromatic extract (DAE). In this work, this oil was substituted by oils with low levels of polycyclic aromatic hydrocarbons (PAHs): treated residual aromatic extract (TRAE) and two naphthenic oils from different suppliers (HN1 and HN2). This substitution was performed in response to REACH Regulation (EC No. 1907/2006 European Parliament and the Council of December 18, 2006, Annex XVII), which state that the sum of individual PAHs should be below 10 mg/kg and the levels of benzo (a) pyrene (BaP) should not exceed 1 mg/kg. Infrared spectroscopy was employed to characterize the structure of crude oils and respective SBR compositions. Thermal properties of the materials were evaluated by thermogravimetry and differential scanning calorimetry. Mechanical properties as tension tests, hardness, abrasion resistance, and resilience were also determined. The final results showed that it is possible to replace the extender oil DAE for any of the oils tested, specially the naphthenic HN1, without any loss of the properties evaluated in this study for the SBR compositions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
103.
104.
105.
106.
CuBr2‐induced charge screening on photoactive nanocolloidal polypyrrole:poly(styrene sulfonate) composite multilayer thin‐film counter electrodes for high‐efficiency dye‐sensitized solar cells 下载免费PDF全文
S Maruthamuthu J Chandrasekaran D Manoharan SN Karthick Hee‐Je Kim B Saravanakumar 《Polymer International》2016,65(5):584-595
Nanocolloidal polypyrrole (PPy):poly(styrene sulfonate) (PSS) particles were synthesized by chemical oxidative polymerization using 15 wt% of PSS. The highly processable polymer composite (PPy:PSS) was spin‐coated at 4000 rpm on fluorine‐doped tin oxide glass and subsequently employed as a counter electrode (CE) for dye‐sensitized solar cells (DSCs). PPy:PSS multilayer (one, three, five) CEs were treated with CuBr2 salt, which enhances the efficiency of the DSCs. Optical studies reveal that a bulkier counterion hinders interchain interactions of PPy which on salt treatment shows a moderate redshift in absorption maxima. Salt‐treated PPy:PSS films exhibit lower charge transfer resistance, higher surface roughness and better catalytic performance for the reduction of I3?, when compared with untreated films. The improved catalytic performance of salt‐treated PPy:PSS multilayer films is attributed to charge screening and conformational change of PPy, along with the removal of excess PSS. Under standard AM 1.5 sunlight illumination, salt treatment is shown to boost the efficiency of multilayer PPy:PSS composite film‐based DSCs, leading to enhanced power conversion efficiency of 6.18, 6.33 and 6.37% for one, three and five layers, respectively. These values are significantly higher (ca 50%) than those for corresponding devices without CuBr2 salt treatment (3.48, 2.90 and 2.01%, respectively). © 2016 Society of Chemical Industry 相似文献
107.
Chenze Qi Youhua Hu Genzhong Ji Weimin Liu Fengyuan Yan Xiaoming Zheng 《应用聚合物科学杂志》2001,81(12):2964-2971
Diethyl‐2,3‐dicyano‐2,3‐di‐(X‐substituted phenyl) succinates (X = p‐OCH3, p‐CH3, p‐Cl, H, p‐NO2) can initiate the free‐radical polymerization of styrene. The decomposition rate constant and activation energy were measured by means of a dilatometer, and the results showed that they were strongly dependent on the ratio of meso‐ and dl‐isomers in the polysubstituted dibenzyl compounds and the properties of the ring substituents. On the other hand, it was found that the polystyrenes, which were obtained by initiation with hydrogen, had a much larger average molecular weight than that with p‐OCH3 and p‐CH3. The experimental phenomena were correlated with the structure of the radical resulting from hydrogen. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2964–2971, 2001 相似文献
108.
A conductive foam: Based on novel poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer filled by carbon black 下载免费PDF全文
Jihai Zhang Tao Zhou Jing Zhao Canyao Yuan Liping Xia Ningfeng Sun Weidong Zhang Aimin Zhang 《应用聚合物科学杂志》2015,132(11)
In this article, a conductive foam based on a novel styrene‐based thermoplastic elastomer called poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene‐b‐butadiene‐b‐styrene) tri‐block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross‐linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180°C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30–50 µm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 × 106 to 6.20 × 107 cells/cm3) and a rapid thinning of the cell walls (from 45.3 to 1.4 µm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48–0.09 g/cm3 and the volume resistivity of 3.1 × 103?2.5 × 105 Ω cm can be easily prepared in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41644. 相似文献
109.
针对含环氧丙烷和苯乙烯/丙烯腈的聚醚装置工业废气,提出了冷却-吸收法废气处理工艺方案。采用专业软件,对废气吸收工艺过程进行了模拟研究。考察了废气冷却温度、吸收水温度及流量、吸收塔理论板数对吸收效果的影响,确定了适宜的废气处理工艺参数。在冷却温度15℃,吸收水温度10℃,吸收水用量17t/h,吸收塔理论板数为26的工艺条件下,废气处理后排放尾气中有机物浓度小于80mg/m3,达到环保排放要求。研究结果表明,冷却-吸收法处理聚醚废气工艺是可行的。 相似文献
110.
将废弃电路板回收处理后得到的非金属粉末掺入水泥砂浆中,研究非金属粉末粒径大小对水泥砂浆性能的影响;为改善非金属粉末和水泥浆体之间的界面性能进而改善复合砂浆的性能,采用硅烷偶联剂处理非金属粉末和在砂浆中加入丁苯乳液2种改性方法.结果表明:硅烷偶联剂处理可以降低砂浆的含气量和收缩率,加入丁苯乳液改善了砂浆的抗压强度和毛细孔吸水率.偶联剂处理和加入丁苯乳液都可以提高砂浆的抗折强度和黏结抗拉强度.废弃电路板非金属粉末粒径越小,水泥砂浆的抗压强度、抗折强度和黏结抗拉强度越大,含气量、收缩率和毛细孔吸水率越小. 相似文献