全文获取类型
收费全文 | 14005篇 |
免费 | 2177篇 |
国内免费 | 864篇 |
专业分类
电工技术 | 170篇 |
综合类 | 913篇 |
化学工业 | 6465篇 |
金属工艺 | 727篇 |
机械仪表 | 313篇 |
建筑科学 | 674篇 |
矿业工程 | 306篇 |
能源动力 | 917篇 |
轻工业 | 591篇 |
水利工程 | 215篇 |
石油天然气 | 726篇 |
武器工业 | 54篇 |
无线电 | 1018篇 |
一般工业技术 | 3280篇 |
冶金工业 | 411篇 |
原子能技术 | 116篇 |
自动化技术 | 150篇 |
出版年
2024年 | 79篇 |
2023年 | 432篇 |
2022年 | 501篇 |
2021年 | 668篇 |
2020年 | 612篇 |
2019年 | 610篇 |
2018年 | 577篇 |
2017年 | 666篇 |
2016年 | 652篇 |
2015年 | 669篇 |
2014年 | 818篇 |
2013年 | 981篇 |
2012年 | 1002篇 |
2011年 | 984篇 |
2010年 | 656篇 |
2009年 | 841篇 |
2008年 | 676篇 |
2007年 | 798篇 |
2006年 | 753篇 |
2005年 | 664篇 |
2004年 | 562篇 |
2003年 | 498篇 |
2002年 | 419篇 |
2001年 | 363篇 |
2000年 | 362篇 |
1999年 | 215篇 |
1998年 | 160篇 |
1997年 | 135篇 |
1996年 | 120篇 |
1995年 | 101篇 |
1994年 | 77篇 |
1993年 | 54篇 |
1992年 | 75篇 |
1991年 | 53篇 |
1990年 | 60篇 |
1989年 | 55篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1959年 | 3篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
由于干态聚合物电解质目前还不能满足聚合物锂离子电池的应用要求,人们致力于开发含液体增塑剂的聚合物电解质,包括凝胶型和微孔型两类体系。本文综述了含液聚合物电解质的最新进展,重点论述了各种新体系和新方法。 相似文献
4.
Daniela M. Nevskaia Maria Luisa Rojas Cervantes Antonio Guerrero Ruíz Juan de Dios Lpez Gonzlez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):249-256
Adsorption of Triton X-100 on various silica substrates has been investigated. A number of solids, including a natural quartz, this quartz washed with HCl acid and subsequently heated at 1273 K; two aerosils and one Kieselgel silicas were studied. These solids exhibit surface areas in the range of 5 to 430 m2 g?1. All the Triton adsorption isotherms display an S-shape at the adsorption temperatures studied (298 and 308 K). It has been found that the pretreatments of natural quartz (by water washing, impurities removed by acid and/or high temperature calcination) affect considerably the amounts of TX-100 adsorbed. Measurements of surface composition have been made by X-ray photoelectron spectroscopy (XPS) with particular emphasis on the presence of impurities and on the number of OH groups at the surface of the samples. The nature of the surface hydroxyl has also been studied by infrared spectroscopy. Furthermore, the specific number of hydroxyl groups on the surface of the silica samples has been determined by thermogravimetric analysis. Finally an attempt to correlate solid surface characteristics with adsorption isotherms has been developed. 相似文献
5.
NaY晶化母液制备硅铝胶的技术探讨 总被引:3,自引:0,他引:3
在导向剂法合成Y型分子筛的工艺下,晶化母液中SiO2的含量为50~55g/l,Na2O含量为20~25g/l,相当于模数为1.65~2.58的稀水玻璃,将晶化母液分离处理后,在晶化母液中加入一定量的硫酸铝溶液使硅沉淀,经过滤和水洗后即可制备出合格的硅铝胶,以便进行重新利用。 相似文献
6.
Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry 相似文献
7.
The work focuses on the synthesis of a red ceramic pigment by inclusion of hematite in a fumed silica matrix with different specific surface areas. Iron(II) sulfate was used as hematite precursor. Mixtures of iron(II) sulfate and fumed silica with different mole ratios were heated at different temperatures from 1000 to 1300 °C for 4 h. 相似文献
8.
Patricio Toro Raúl Quijada Omar Murillo Mehrdad Yazdani‐Pedram 《Polymer International》2005,54(4):730-734
The mechanical, morphological behavior and water absorption characteristics of polypropylene (PP) and silica, or PP and rice‐husk, composites have been studied. The silica used in this study as filler was a commercial type produced from soluble glass or rice husks. The compatibilizing effect of PP grafted with monomethyl itaconate (PP‐g‐MMI) and/or with vinyltriethoxysilane (PP‐g‐VTES) as polar monomers on the mechanical properties and water absorption was also investigated. In general, a high loading of the studied fillers in the polymer matrix increases the stiffness and the water absorption capacity. This effect is more noticeable in the tensile modulus of the PP/silica composite with PP‐g‐VTES as compatibilizer. However, the increase of the rice‐husk charge as a natural filler in the PP matrix decreases the stiffness, and in the presence of PP‐g‐MMI as compatibilizer in PP/rice‐husk, the tensile modulus and water absorption of the composite were improved. The better adhesion and phase continuity in the PP/silica and PP/rice‐husk composites with different compatibilizers was confirmed by the morphological study. Copyright © 2004 Society of Chemical Industry 相似文献
9.
10.
用试井方法确定注水后地层渗透率的变化 总被引:1,自引:0,他引:1
大港油田已进入开发中后期,高含水油田占73%,开发初期的一些参数已不适合现在开发的需要。研究出一套用试井方法确定注水以后地层渗透率变化的方法,对大港油田的增储上产具有重要意义。 相似文献