首页 | 官方网站   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   1084篇
  免费   94篇
  国内免费   35篇
工业技术   1213篇
  2023年   29篇
  2022年   10篇
  2021年   31篇
  2020年   21篇
  2019年   29篇
  2018年   28篇
  2017年   33篇
  2016年   26篇
  2015年   24篇
  2014年   27篇
  2013年   39篇
  2012年   49篇
  2011年   92篇
  2010年   53篇
  2009年   81篇
  2008年   53篇
  2007年   66篇
  2006年   66篇
  2005年   83篇
  2004年   84篇
  2003年   67篇
  2002年   57篇
  2001年   33篇
  2000年   30篇
  1999年   23篇
  1998年   18篇
  1997年   11篇
  1996年   6篇
  1995年   1篇
  1994年   14篇
  1993年   4篇
  1992年   2篇
  1991年   3篇
  1990年   5篇
  1989年   2篇
  1988年   5篇
  1987年   3篇
  1985年   2篇
  1983年   2篇
  1978年   1篇
排序方式: 共有1213条查询结果,搜索用时 14 毫秒
1.
2.
原位插层聚合制备PVC/蒙脱土纳米复合材料   总被引:15,自引:5,他引:10  
采用氯乙烯单体直接插层到蒙脱土中进行原位插层聚合,制备纳米复合材料,并用小角X射线衍射(XRD)、扫描电子显微镜(SEM)和电子探针技术对复合材料进行了结构表征。实验结果表明:采用原位插层聚合法制得的PVC/蒙脱土(MMT)复合材料为剥离型纳米复合材料。  相似文献   
3.
在多层合试合采工艺实施过程中,经常会遇到地层水的问题,通常采用的挤水泥或化学堵剂的办法不仅成本高且工艺复杂,而使用常规封隔器又达不到封堵效果。Y445(3)型封隔器 Y341(Ⅱ)型封隔器的悬挂式封隔组合管柱堵水工艺,满足了封堵水层、采气的要求。  相似文献   
4.
以微粉石墨为主体材料合成出不同阶结构的FeCl3-NiCl2-GICs.应用XRD、SEM对产物的晶体结构与表面形貌进行分析表征.采用范德保法测量产物在常温常态下的电阻率,用MODEL9600振动磁强计测量GICs在0~7.958×105A/m磁场强度下的磁化强度、磁化率.测量数据表明异类原子FeCl3、NiCl2插入石黑层间后,GICs的电导率增加1.3~2.9倍,其磁性由石墨的抗磁性转变为顺磁性.  相似文献   
5.
二维无机功能材料   总被引:5,自引:0,他引:5  
陈祖熊 《功能材料》1994,25(3):280-284
简要介绍了一种通过层状结构材料剥离成单分子层的无机二维功能材料。  相似文献   
6.
In this work we investigated the mechanism of the electrochemical intercalation reactions in rf sputtered nickel oxide thin films electrodes by two techniques: mechanical stress change measurements by means of an optical technique and mass changes using an electrochemical quartz microbalance (EQCM). The experiments were performed in alkaline electrolytes containing cations of the first column of the periodic table. Reversible mass and volume changes were observed. In order to explain these experimental results, an exchange reaction is proposed, in which the oxidation process is accompanied by the deinteractional of a relative large number of “light” cations, simultaneously with the intercalation of a smaller number of heaviest cations.  相似文献   
7.
Synthesis and properties of polystyrene/graphite nanocomposites   总被引:3,自引:0,他引:3  
In this paper, graphite/polystyrene nanocomposite is synthesized by in situ polymerization of styrene in a tetrahydrofuran (THF) solution system of potassium (K)-THF-graphite intercalation compound (GIC). K-THF-GIC has proved to initiate polymerization of styrene by the anionic mechanism. Due to the interfacial interaction between the graphite nanolayers and the polymer, the composites exhibit higher glass transition temperature and higher thermal stability when compared to polystyrene. The percolation threshold in the conductivity of the composites is lesser than 8.2 wt% and the dielectric constant can reach as high as 136.  相似文献   
8.
In order to produce thin films of crystalline V2O5, vanadium metal was thermally oxidised at 500 °C under oxygen pressures between 250 and 1000 mbar for 1-5 min. The oxide films were characterised by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The lithium intercalation performance of the oxide films was investigated by cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS). It was shown that the composition, the crystallinity and the related lithium intercalation properties of the thin oxide films were critically dependent on the oxidation conditions. The formation of crystalline V2O5 films was stimulated by higher oxygen pressure and longer oxidation time. Exposure for 5 min at 750 mbar O2 at 500 °C resulted in a surface oxide film composed of V2O5, and consisting of crystallites up to 200 nm in lateral size. The thickness of the layer was about 100 nm. This V2O5 oxide film was found to have good cycling performance in a potential window between 3.8 and 2.8 V, with a stable capacity of 117 ± 10 mAh/g at an applied current density of 3.4 μA/cm2. The diffusion coefficients corresponding to the two plateaus at 3.4 and 3.2 V were determined from the impedance measurements to (5.2 and 3.0) × 10−13 cm2 s−1, respectively. Beneath the V2O5 layer, lower oxides (mainly VO2) were found close to the metal. At lower oxygen pressure and shorter exposure times, the oxide films were less crystalline and the amount of V4+ increased in the surface oxide film, as revealed by XPS. At intermediate oxygen pressures and exposure times a mixture of crystalline V2O5 and V6O13 was found in the oxide film.  相似文献   
9.
High impact polystyrene/Fe-montmorillonite (HIPS/Fe-MMT) nanocomposites were successfully prepared by melting intercalation. The nanostructures of HIPS/Fe-MMT were testified by X-ray diffraction (XRD) and transmission electron microscope (TEM). Corresponding to pure HIPS, the thermal stability of HIPS/Fe-MMT nanocomposites was notably improved. The peaks of heat release rate (PHRR) and the mass loss rate (MLR) were significantly reduced after the formation of the HIPS/Fe-MMT nanocomposites from cone calorimetry. And nanocomposites PHRR was further lower with the increase of Fe-MMT content in the range of 1 to 5 wt%. The degradation mechanism of HIPS and HIPS/Fe-MMT nanocomposites was conducted by pyrolysis gas chromatography mass spectrometry (Py-GC-MS). And the reason of the enhancement of thermal stability maybe is that structural iron is the operative site for radical trapping in the Fe-MMT and the nanostructure enhances the interaction of the chains of the HIPS.  相似文献   
10.
陆相碎屑岩储层隔夹层成因、特征及其识别   总被引:18,自引:1,他引:17  
陆相储层隔夹层是形成储层流体流动非均质的主要因素之一,也是储层精细表征的重要内容,油田勘探开发实践表明,陆相储层隔夹层主要可分为泥质隔夹层、钙质隔夹层和物性隔夹层三大类。根据这种分类,深入分析和总结了这三类隔夹层成因、岩性特征、分布特征和测井识别特征,并比较其区别,这对以后新老区块隔夹层研究有参考和适用价值。  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-23

京公网安备 11010802026262号