首页 | 本学科首页   官方微博 | 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   34篇
  免费   4篇
  国内免费   7篇
化学   24篇
晶体学   1篇
物理学   20篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2017年   1篇
  2016年   2篇
  2015年   3篇
  2014年   2篇
  2013年   3篇
  2012年   3篇
  2011年   3篇
  2010年   2篇
  2009年   2篇
  2008年   3篇
  2007年   6篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  2001年   1篇
  1998年   3篇
  1997年   1篇
  1992年   1篇
排序方式: 共有45条查询结果,搜索用时 359 毫秒
1.
合成了硫氰酸铈(Ⅲ)与三缩四乙醇配合物[Ce(C_8H_(18)O_5)(NCS)_3(H_(2)O)].晶体结构分析表明,该配合物晶体属三斜晶系,P(?)空间群.晶胞参数:a=0.8816(3)nm,b=1.0465(2)nm,c=1.2490(2)nm,α=86.46(1)°,β=70.90(2)°,γ=66.37(2)°,ν=0.9943nm~(3),Z=2.D_(计算)=1.769cm~(3),最终偏差因子R=0.049.  相似文献   
2.
A microwave distillation method was optimized for the extraction and isolation of cannabis essential oil from fresh and dried hemp inflorescences. The developed method enabled us to obtain a distilled product rich in terpenes and terpenoid compounds, responsible of the typical and unique smell of the cannabis plant. The distillate from different hemp cultivars, including Kompolti, Futura 75, Carmagnola, Felina 32 and Finola were characterized by using a gas chromatograph equipped with both mass spectrometer and flame ionization detectors. In a single chromatographic run, the identity and absolute amounts of distilled compounds were determined. Peak assignment was established using a reliable approach based on the usage of two identification parameters, named reverse match, and linear retention index filter. Absolute quantification (mg g−1) of the analytes was performed using an internal standard method applying the flame ionization detector (FID) response factors according to each chemical family. An enantio-GC-MS method was also developed in order to evaluate the enantiomeric distribution of chiral compounds, an analytical approach commonly utilized for establishing the authenticity of suspicious samples.  相似文献   
3.
电光高分子材料由于其在光电子信息领域的潜在应用前景已得到了广泛关注和深入研究.本文在简要介绍电光效应及其材料等相关知识的基础上,综述了最近几年来电光高分子材料的研究进展,主要包括生色团的设计与合成,以及掺杂型、侧链型、主链型、交联型、互穿网络型和树枝型等聚合物材料体系的设计与合成.  相似文献   
4.
The crystal of title compounds belongs to orthorhombic system with space group P212121 (No.19). The cell parmeters are a=1.432 16(3) nm, b=1.457 20(3) nm, c=3.005 85(6) nm, and V=6 273.0(2) nm3, Z=8, μ(Mo )=22.21 cm-1Dc=1.802 g·cm-3, F(000)=3 416.00, Finally R1=0.033 and wR2=0.073 (I>2.00σ(I)), S=1.023. Every center atom Sm(Ⅲ) is surrounded by the two aether chains, the title compound has ten-coordinate structure and the coordination polyhedron shows a Bicapped Square Antiprism. In the crystal, the title compound has the flack of double moleculars and non-symmetry. The anion ClO4- does not take part in the coordination. CCDC: 238709.  相似文献   
5.
声电光效应的耦合波方程理论   总被引:9,自引:2,他引:7  
俞宽新  赵启大 《光学学报》1998,18(4):66-470
将声光效应与电光效应的耦合波方程相结合,统一为声电光效应的耦合波方程,并对之进行求解,给出声电光效应的衍射效率公式。  相似文献   
6.
The cubic boron nitride (cBN) is a kind of artificial electro-optic (EO) crystal, and we have not found any relative reports so far. Because the artificial synthetic cBN wafers are very small and hard, the wafers cannot be cut into rectangular slabs. The polarizer-sample-λ/4 retardation plate (compensator)-analyzer (PSCA) transverse EO modulator has to be adjusted to the minute irregular octahedron of cBN wafers. When the applied voltage is along [1 1 1] direction of the wafer, due to refraction, the angle between the incident beam direction and the (1 1 1) plane (top or bottom plane) of the wafer should be 25.4°, and the angle between the polarization direction of the polarizer and the plane of incidence should be 50.8° by calculation, respectively. The half-wave voltage of the cBN sample was obtained for the first time, by means of detection of the output optic signals from the modulator with and without an applied electric field on the sample, respectively. Furthermore, the linear EO coefficient was obtained, . The analysis of the experimental resulting error was carried out.  相似文献   
7.
In this study, the dye-doped polymer dispersed liquid crystals (PDLC) gratings techniques performed by the various research groups or being developed are briefly reviewed. Especially, the electrically switched diffraction and holographic gratings, have attained much attention by various research groups working in the PDLC-related display studies. The fabrication methodologies used for such grating texture, include like the conventional dye-doped PDLC grating, Azo-dye doped PDLC gratings, and lasing techniques etc., adopted for dye-doped PDLC gratings. The useful features and characteristics of their fabrication process of such gratings are discussed. Finally, some of the future perspectives on this particular research field are presented.  相似文献   
8.
Jie Sun 《Optics Communications》2009,282(11):2255-2258
A polarisation-insensitive electro-optic (EO) waveguide consisting of a dye-doped TiO2/SiO2 slab and a SU-8 strip-loaded rib is designed and fabricated. By optimizing the refractive index and size of waveguide, a trade-off between polarisation-insensitive condition and large EO efficiency (optical field interaction with the EO material) is obtained. The average transmission loss of the waveguide is less than 2.0 dB/cm. A Mach-Zehnder (M-Z) interferometer intensity modulator based on this waveguide with excellent poling stability is fabricated and measured, exhibiting 7 V half-wave voltage with 1.8 cm EO interaction length and 2.7 cm total length. This strip-loaded structure is proved to be a valuable application in EO modulators and switches.  相似文献   
9.
乙基橙-溴酸钾体系动力学光度法测定痕量甲醛   总被引:6,自引:0,他引:6  
研究了在稀H2SO4介质中,痕量甲醛催化KBrO3氧化乙基橙褪色反应的适宜条件和影响因素,建立了测定痕量甲醛的动力学光度法。方法采用固定时间法于507 nm波长处测量体系的吸光度,在适宜条件下,ΔA与甲醛质量浓度具有良好的线性关系,方法的线性范围为0~0.24 mg/L,检出限为0.004 mg/L。该方法用于饮料、废水和废气中痕量甲醛的测定,测定结果的相对标准偏差RSD≤3%(n=6),回收率为102%。  相似文献   
10.
三嵌段共聚物EO20PO70EO20相分离行为的耗散粒子动力学模拟   总被引:1,自引:0,他引:1  
采用耗散粒子动力学(DPD)方法研究了嵌段共聚物EO20PO70EO20(P123)在水、乙醇/水溶液及二氧化硅溶胶体系中的相分离行为. 不同质量分数的P123在水溶液中共形成4种相分离状态: 球状胶束(10%); 椭球胶束(20%)、棒状胶束(30%)和三维立方胶束(50%). 在模板剂质量分数为10%的乙醇/水溶液中, 模板剂胶束稳定性随着乙醇含量的增加而变差. 在二氧化硅溶胶体系中, 模板剂质量分数低于5%时无胶束形成; 模板剂质量分数增至10%时, P123发生相分离形成三维球状胶束; 随着模板剂质量分数的进一步增加, 模板剂分子夹含着水分子形成三维椭球状结构(20%)、三维立方结构(40%)和层状结构(60%). 模拟结果与实验结果一致, 说明DPD模拟可以从计算角度推测模板剂对介孔材料结构的影响.  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