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   52篇
  免费   2篇
化学工业   19篇
建筑科学   1篇
能源动力   4篇
轻工业   1篇
无线电   6篇
一般工业技术   8篇
冶金工业   6篇
自动化技术   9篇
  2024年   1篇
  2023年   1篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2013年   3篇
  2012年   5篇
  2011年   4篇
  2010年   2篇
  2009年   3篇
  2008年   3篇
  2007年   4篇
  2006年   1篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  1999年   1篇
  1998年   3篇
  1997年   4篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1989年   1篇
排序方式: 共有54条查询结果,搜索用时 15 毫秒
51.
Deficiency Analysis of Coastal Buildings toward Storm Damage Reduction   总被引:1,自引:0,他引:1  
Engineering services provided by one of the writers to property owners, insurance companies, attorneys, and others have resulted in a compilation of case studies, based on more than 1,000 site inspections, suitable to generate a database regarding various aspects of building performance. The scope of those services typically included identifying the cause and origin of damage to residential and commercial structures, as well as an estimation of the magnitude of damage sustained by those structures. The majority of those damaged structures was located in proximity to a coastal region and experienced recent exposure to a storm or other weather event. Compilation of data from those case studies allowed identification and ranking of the occurrence of chronic building problems. It has become apparent that building-related deficiencies often exist as a common feature in similar structures. Some of those recurring deficiencies could be eliminated with alternate building design, better construction practices, or proper routine maintenance procedures. Where applicable, proposed remedial solutions are presented for specific building deficiencies or problems identified.  相似文献   
52.
1 Background The subject of management fads is well covered in the literature with typical definitions: (1) It is normally a new idea. (2) It is developed in a vague and previously undefined area. (3) It is about what its users are initially enthusiastic about, even though they can quickly lose interest in it [1]. Van der Wiele[2] explores many characteristics of fads, pointing out that; (1) Fads can develop in an area of activity, which is not well defined. (2) Most fads are not really new …  相似文献   
53.
The synthesis of neutral dinuclear iron–nickel unsymmetrical Schiff base complexes 3 and 4 was achieved via a template reaction involving equimolar amounts of alkyl or aryl “half-unit” precursors, respectively, Fc–C(O)CH=C(CH3)N(H)R (1: R = CH2CH2NH2; 2: R = o-C6H4NH2; Fc = CpFe(η5-C5H4); Cp = η5-C5H5), 5-bromosalicylaldehyde and nickel(II) acetate tetrahydrate in a refluxing CH2Cl2/MeOH (1:1) mixture. The ionic trinuclear unsymmetrical complex 5 was prepared by reacting its dinuclear precursor 3 with the arenophile source, [Cp*Ru(NCCH3)3]PF6 (Cp* = η5-C5(CH3)5), in refluxing CH2Cl2 for 2 h, whereas the trinuclear species 6 was formed upon regioselective π-complexation of the 5-bromosalicylidene ring of 4 by [Cp*Ru]+ at room temperature overnight. All the new compounds were adequately characterized by analytical and spectroscopic techniques and, in addition, the crystal and molecular structures of the “half-unit” 1, the binuclear complex 4 and its hemisolvate adduct 4 · 0.5CH3OH, the trinuclear Schiff base compound 5 · 2(CH3)2CO, and the mixed sandwich metalloligand 7 have been determined by X-ray crystallography. Both organometallic–inorganic hybrids 5 and 6 contain the neutral electron-releasing ferrocenyl group, and the cationic electron-withdrawing ruthenium mixed sandwich, linked through the unsymmetrical tetradentate Schiff base complex {Ni(ONNO)}. UV–vis, 1H and 13C NMR as well as electrochemical data clearly indicate a mutual donor–acceptor electronic influence between the organometallic termini. Furthermore, X-ray crystal structure analysis of 5 · 2(CH3)2CO reveals the partial delocalization of bonding electron density throughout the dinucleating nickel Schiff base ligand. Dedicated to Prof. Didier Astruc, a true friend, an outstanding lecturer and scientist, in honor of his pioneering research efforts and accomplishments in the fields of organometallic chemistry, dendrimers and their applications in nanocatalysis.  相似文献   
54.
Sillenite-type ceramics are non-centrosymmetric phases of ongoing research interest because of their structural defects and optoelectronic properties. We report a series of sillenite compounds with a general composition Bi12(Bi3+4/5−3xIn3+5x1/5−2x)O19.2+3x0.8−3x for x = 0.03–0.27 to understand how the crystal–physicochemical properties change with a successive filling of empty Bi3+ positions in the tetrahedral site by In3+ cation. Conventional solid-state synthesis method is used to prepare the microcrystalline samples. Each sample is characterized by X-ray diffraction, Raman, UV/Vis diffuse reflectance spectroscopy, and thermogravimetry (TG/DSC). X-ray powder data Rietveld refinement reveals that phase-pure samples can be obtained for x = 0.03–0.08 in the space group I23. Appearance of starting In2O3 as minor phases with the final products for 0.10 < x < 0.27 suggests for xmax = 0.08. The successive decrease of the lattice parameter indicates the incorporation of smaller In3+ cations in the structure. The effect of the lone electron pairs of Bi3+ and the structural cation vacancies lead to the modification of the interatomic bond lengths. At least one Raman active phonon mode shows hardening for decreasing cation vacancy concentration in the system. The bandgap energy increases with increasing indium content. An additional absorption band at lower energy for x = 0.03–0.08 complements the theoretical study, which completely disappears for x > 0.08. The stronger In–O bonds play pivotal roles in the thermal stability of the phases studied by TGA/DSC analysis.  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