全文获取类型
收费全文 | 75篇 |
免费 | 4篇 |
国内免费 | 18篇 |
专业分类
化学 | 83篇 |
晶体学 | 4篇 |
力学 | 3篇 |
物理学 | 7篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 7篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
排序方式: 共有97条查询结果,搜索用时 498 毫秒
1.
A novel hydrogen bonded liquid crystal (HBLC) complex is synthesized from non-mesogenic benzylmalonic acid (BMA) and mesogenic 4-nonyloxybenzoic acid (9OBA). Structural properties and optimized vibrational frequencies of BMA + 9OBA have been studied by FT-IR spectrum. The weak intermolecular interaction between the molecules is proved by NBO and Mulliken charge distribution analysis. The optical and thermal properties are investigated by POM, DSC, UV-Visible and PL techniques. The present HBLC complex exhibits schlieren textures of nematic, broken focal conic texture of smectic C and multicolored mosaic texture of smectic G phases respectively which is not observed in the pure mesogen (9OBA). The HBLC complex geometry is optimized by DFT method at the level of B3LYP basis set 6311G (d, p). The electronic properties of HBLC complex such as, NBO, HOMO-LUMO, ESP and Mulliken charge distribution are also studied. A noteworthy observation is brought out by identifying the presence of photoluminescence in nematic phase due to the variation in intermolecular interaction of the mesophase. The utility of the same complex is discussed. The phase width, thermal stability factor, tilt angle, phase transition temperature and its enthalpy values are reported. 相似文献
2.
3.
考察了反应温度、气体空速和进料中CH4:O2比值对Mo2C/Al2O3催化的POM反应制合成气的影响.结果发现较高的温度具有较高的甲烷转化率、CO和H2的选择性;而在较低的温度下,对CO的选择性比对H2的影响更大.反应气体的空速较小时对于甲烷的转化率、CO和H2的选择性是有利的;而在较高的气体空速下,氢气的选择性则更低.进料中CH4:O2比值稍高于2:1时有利于获得高的甲烷转化率、CO和H2的选择性.并且还可以增加催化剂的稳定性.当CH4:O2比值低于2:1时.甲烷转化率、CO和H2选择性随反应的进行急剧下降.而当此比值调整到高于2:1时.转化率和选择件都可以得到恢复。 相似文献
4.
Photocatalysis has been extensively studied due to its potential ability to avoid the excessive use of chemical reagents and reduce the energy consumption by employing solar energy. Moreover, to alleviate the reduction in the membrane permeation selectivity, separation efficiency, and membrane service life caused by the emerging micro-pollutants and membrane fouling, membrane technology is often coupled with microbial, electrochemical, and catalytic processes. However, although physical/chemical cleaning and membrane module replacement can overcome the inherent limitations caused by membrane fouling and other membrane separation processes, high operating costs limit their practical applications. In this review, common preparation methods for TiO2 photocatalytic membranes are described in detail, and the main approaches to enhancing their photocatalytic performance are discussed. More importantly, the mechanism of the TiO2 photocatalytic membrane antifouling process is elucidated, and some applications of photocatalytic membranes in other areas are described. This review systematically outlines future research directions in the field of photocatalytic membrane modification, including metal and non-metal doping, fabrication of heterojunction structures, control over reaction conditions, increase in hydrophilicity, and increase in membrane porosity. 相似文献
5.
The one-dimensional chain self-assembled coordination polymer, [Cd(SCN)2(POM)2]n(where POM is 3-methyl-4-nitropyridine-N-oxide), was synthesized and characterized. The crystal data for the title coordination polymer: monoclinic, space group P21/c, a = 1.182 3(1) nm, b = 0.591 1(1) nm, c = 1.419 2(1) nm, β = 102.875(1)°, Z=2, μ = 1.391 mm-1, final R1 = 0.062 8, wR2 = 0.145 2. The coordination polymer exhibits a strong fluorescent emission band at ca. 518 nm. CCDC: 211506. 相似文献
6.
Taibi Ben Hadda Fatim Z. Khardli Mostafa Mimouni Maria Daoudi Abdelali Kerbal Héctor Salgado-Zamora 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):753-761
AbstractA series of four different armed heterocyclic candidates; 1-(2-methyl-2,3-dihydro-1,3-benzothiazol-2-yl)acetone (2), 1-(3-methyl-4H-1,4-benzothiazin-2-yl)ethanone (3), 2-[(2-aminophenyl)dithio]aniline (4), and 3-hydroxy-3-methyl-4-(3-methyl-2-quinoxalinyl)-2-butanone (5) have been prepared and their microbial activities were evaluated. A correlation of the structure and activities relationships of these compounds with respect to molecular modeling, Lipinski Rule of Five, drug likeness, toxicity profiles, and other physico-chemical properties of drugs are described and verified experimentally. 相似文献
7.
通过水热合成得到了一个新颖的包含四核铜配合物的无机-有机杂化化合物[CuCl(H2O)4)][CuCl(H2O)(Phen)][{(CuPhen)2Cl2}2(bdc)]2[P2W18O62]·5H2O(1)(Phen=1,10-phenanthroline和bdc=1,4-benzenedicarboxylate),对其进行了元素分析、红外光谱、热重、电化学等表征,并用X-射线单晶衍射测定了它的晶体结构。化合物1含有由Cl和bdc桥连的四核铜配合物阳离子[{(CuPhen)2Cl2}2(bdc)]2+。此外,化合物1的电化学研究表明其对亚硝酸的还原具有很好的电催化活性。 相似文献
8.
The phase behaviour of the binary systems 4′- n -tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)- n -alkane ( n -tetradecane or n -hexadecane) was investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The phase behaviour was a function of temperature ( T ) and the effective carbon number of the system ( n*), where n* involves carbon atoms both from the alkoxy group of ANBC-14 and from the n -alkane added. ANBC-14 shows no cubic phase, but the addition of n -alkane induced cubic phases when n*≧c. 15. An interesting point is that the type of cubic phase is Ia 3 d for 15≦n*≦17, while an Im 3 m type is formed for 18≦n*≦20. Furthermore, for n* = 22, two types of cubic phase, one with Im 3 m symmetry in the low temperature region and the other with Ia 3 d in the high temperature region, were observed both on heating and cooling. The phase diagram with respect to T and n* is very similar to that of pure one-component ANBC- n , which is a function of T and the number of carbon atoms in the alkoxy group n . 相似文献
9.
R.B. Shinde N.S. Padalkar S.V. Sadavar A.S. Patil S.B. Kale V.V. Magdum Y.M. Chitare S.P. Kulkarni U.M. Patil V.G. Parale J.L. Gunjakar 《Materials Today Chemistry》2022
Tuning the interior chemical composition of layered double hydroxides (LDHs) via lattice engineering route is a unique approach to enable multifunctional applications of LDHs. In this regard, the exfoliated 2D LDH nanosheets coupled with various guest species lead to the lattice-engineered LDH-based multifunctional self-assembly with precisely tuned chemical composition. This article reports the synthesis and characterization of mesoporous zinc–chromium-LDH (ZC-LDH) hybridized with isopolyoxovanadate nanohybrids (ZCiV) via lattice-engineered self-assembly between delaminated ZC-LDH nanosheets and isopolyoxovanadate (iPOV) anions. Electrostatic self-assembly between 2D ZC-LDH monolayers and 0D iPOV significantly altered structural, morphological, and surface properties of ZC-LDH. The structural and morphological study demonstrated the formation of mesoporous interconnected sheet-like architectures composed of restacked ZCiV nanosheets with expanded surface area and interlayer spacing. In addition, the ZCiV nanohybrid resistive elements were used as a room-temperature gas sensor. The selectivity of ZCiV nanohybrid was tested for various oxidizing (SO2, Cl2, and NO2) gases and reducing (LPG, CO, H2, H2S, and NH3) gases. The optimized ZCiV nanohybrid demonstrated highly selective SO2 detection with the maximum SO2 response (72%), the fast response time (20 s), low detection limit (0.1 ppm), and long-term stability at room temperature (27 ± 2 °C). Of prime importance, ZCiV nanohybrids exhibited moderately affected SO2 sensing responses with high relative humidity conditions (80%–95%). The outstanding SO2 sensing performance of ZCiV is attributed to the active surface gas adsorptive sites via plenty of mesopores induced by a unique lattice-engineered interconnected sheet-like microstructure and expanded interlayer spacing. 相似文献
10.
Yuki Hirayama Morimasa Nakamura Takashi Matsuoka 《Surface and interface analysis : SIA》2020,52(12):850-854
Polyoxymethylene (POM, polyacetal) is one of the most popular plastics for machine elements, especially in Japan. However, it is difficult to use it under severe operating conditions such as high speed and high contact pressure. Diamond-like carbon (DLC) coatings were well known to be tribological and functional coatings. However, both POM and DLC coatings are difficult to adhere them each other. In the present paper, DLC coatings are deposited by plasma-based ion implantation and deposition (PBIID) method on POM substrate, and validity of DLC coatings on POM was investigated through friction and mechanical tests. When gas pressure was 0.2 and 0.8 Pa, hardness and adhesion properties of DLC coating deposited under gas pressure of 0.5 Pa were lower compared with under 0.2 and 0.8 Pa. For preparing DLC coatings having hard and good adhesion properties, relatively thin substrate was suitable. A correlation between relative humidity in the laboratory and friction coefficient was confirmed while DLC coatings remain on the substrate. 相似文献