全文获取类型
收费全文 | 116篇 |
免费 | 3篇 |
国内免费 | 20篇 |
专业分类
化学 | 131篇 |
晶体学 | 2篇 |
力学 | 1篇 |
物理学 | 4篇 |
综合类 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 15 毫秒
1.
Christoph Luef Aloke Paul Jiri Vizdal Ales Kroupa Alexander Kodentsov Herbert Ipser 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):381-395
Summary. The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500°C by a drop calorimetric technique
using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500°C were constructed.
Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well
as the invariant reaction temperature of the ternary eutectic L ⇄ (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found
at 135°C. 相似文献
2.
The compounds [MBr2(p-clan)2] (where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II); p-clan = 4-chloroaniline) were synthesized and characterized by melting points, elemental analysis, thermal analysis and electronic and IR spectroscopy. The enthalpies of solution of the adducts, metal(II) bromides and 4-chloroaniline in methanol, 1.2 M aqueous HCl or 25% (v/v) 1.2 M aqueous HCl in methanol were measures and by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reactions (ΔrH°), the standard enthalpies of formation (ΔfH°), the standard enthalpies of decomposition (ΔDH°), the lattice standard enthalpies (ΔMH°) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (ΔrH°(g)). The mean bond dissociation enthalpies of the metal(II)-nitrogen coordinated bonds and the enthalpies of adduct formation in the gaseous phase have been estimated. 相似文献
3.
在干燥氮气气氛下,以无水乙醇为溶剂,制备了低水合氯化钕与二乙氨基荒酸二乙铵(D-DDC)配合物,确定其组成为Et2NH2[Nd(S2CNEt2)4].单晶结构分析表明,配合物中4个二乙氨基荒酸根各通过2个硫原子与钕离子成键形成八配位十二面体阴离子,并与二乙铵阳离子形成缔合型分子.晶体属单斜晶系,空间群P21/n,a=1.37517(14)nm,b=2.1146(2)nm,c=1.44641(15)nm,β=102.028(2)°,Z=4.用微量热法测定了298.15K下水合氯化钕和D-DDC在无水乙醇中的溶解焓及二乙氨基荒酸钕液相生成反应焓变分别为(-17.89±0.096),(50.280±0.151)和(-10.116±0.065)kJ/mol,求得固相生成反应焓变. 相似文献
4.
Thermochemical Investigations of the Systems Ti/Ni and Ti/Co By treatment of solid Ni or Co with a H2/TiCl4-gas mixture at sufficient high temperature (T ≥ 900°C) the intermetallic phases TiNi3 and TiCo3, resp., are formed. The conversion grade depends on the H2/TiCl4-ratio. From the experimentally determined conversion grades and the known thermodynamic data of all other species existing in equilibrium the free enthalpies and the heats of formation of TiN3 and TiCo3 have been calculated (TiNi3: ΔH(298) = ?133.3 ± 6 kJ/mol; TiCo3: ΔH(298) = ?104.7 ± 6 kJ/mol). 相似文献
5.
Pilar Jiménez Maria Victoria Roux JiŘi Kulhánek Otto Exner 《Structural chemistry》1996,7(5-6):375-381
The energy of combustion of 2,5-dimethoxybenzoic acid has been determined using a static bomb calorimeter. The vapor pressures of the compound have been measured over a 18 K temperature interval by the Knudsen effusion technique. Heat capacity measurements betweenT=270 K andT=338 K were carried out by DSC. From these experimental results the standard molar enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K have been derived. With this compound, the series of mono- and dimethoxy-benzoic acids have been completed. Theirf H
m
o
values were expressed by an additive relationship, taking into account the number of methoxy groups and the number of all 1,2 interactions: an accuracy of 3.3 kJ·mol–1 was achieved. In an alternative approach the substituent effect of the methoxy groups was evaluated within the framework of isodesmic reactions. The effect of disubstitution was referred to mono derivatives and the excess energy—the so-called buttressing effect—was evaluated (2–24 kJ· mol–1 for individual bis derivatives). These values were explained in terms of the conformation of the methoxy group around the Car-O bond. 相似文献
6.
The heat production of Wistar rat polymorphonuclear leukocytes (PMN) was measured by an LKB 2277 Thermal Activity Monitor. When PMN were activited with phorbol-12-myristate13-acetate (PMA), the respiratory burst was recorded by greatly incr eased heat production. Experiment was also carred out in the present of the inhibitor, Total Flavonoids of Lycium Barbarum L. (TFL). The respiratory burst heat production peak was disappeared, but the heat production curve was higher than that of PMA because TFL increased the metabolic activities of PMN. 相似文献
7.
Calorimetric measurements were made on natural sample of lepidolite having the composition (K0.80Na0.05Ca0.07Rb0.16Cs0.03)(Li1.34Al1.40Fe3+0.01)[Si3.25Al0.75O10]F1.80(OH)0.20 from Na-Li-type rare-element-rich pegmatites of East Sayany, Russia. High-temperature enthalpy increments were measured with a Tian-Calvet calorimeter at 444-972 K using the drop method. The resultant (T) equation in the interval T = 298.15-972 K was calculated: = 316.10 + 228.12 × 10−3 T − 50.10 × 105 T−2 (J K−1 mol−1) [± 0.4%] and the value of (298.15 K) = 327.8 J K−1 mol−1 was obtained. The standard molar enthalpy of formation from the elements was determined by high-temperature drop solution calorimetry in molten lead borate at T = 973 K. The value of Δf(298.15 K) for lepidolite was found to be −6201 ± 18 kJ mol−1. The thermodynamic properties of lepidolite of idealized composition KLi1.5Al1.5[Si3AlO10]F2 were estimated based on the experimental data obtained. 相似文献
8.
The thermal decomposition of Co(NO3)2·6H2O (1) as well as that one of NO[Co(NO3)3] (Co(NO3)2·N2O4) (2) was followed by thermogravimetric (TG) measurements, X-ray recording and Raman and IR spectra. The stepwise decomposition reactions of 1 and 2 leading to anhydrous cobalt(II)nitrate (3) were established. In N2 atmosphere, cobalt oxides are finally formed whereas in H2/N2 (10% H2) cobalt metal is produced. Rapid heating of cobalt(II)nitrate hexahydrate causes melting (formation of a hydrate melt) and therefore side reactions in the hydrate melt by incoupled reactions and evolution/evaporation of different species as, e.g., HNO3, NO2, etc. In case of larger amounts in dense packing in the sample container, the formation of oxo(hydoxo)nitrates is possible at higher temperature. For 2, its thermal decomposition to 3 was followed and its decomposition mechanism is proposed. 相似文献
9.
By using an LKB-2277 Bioactivity Monitor, the effect of porphyrin-cholesterol esters on cancer cells HL-60 were examined at
25°C. There is a difference in the shape of the thermogenesis curve samong different kinds of porphyrin-cholesterol esters,
and the death rate of HL-60 cells is also different. The results show that porphyrin-chsterol esters can powerfully inhibit
their metabolism, the inhibitory sequence is II>I>III, but the inhibitory way of each ester is different.
Supported by the National Natural Science Foundation of China
Liu Yi: born in Nov. 1970, Ph. D. graduate student 相似文献
10.
Lithium carbonate (Li2CO3) and ammonium dihydrogen phosphate (NH4H2PO4) were used for synthesizing lithium diphosphate (Li4P2O7). The purity of the latter compound was checked up by X-ray diffraction. The heat of dissolution of (Li4P2O7) in phosphoric acid solution was measured in a C-80 SETARAM calorimeter. Many dilution and mixing processes in acid solutions of several concentrations (w/w) H3PO4, were also realized in the calorimeter in order to get the standard enthalpy of formation of this product. Two thermochemical cycles were investigated and the obtained values for the enthalpy of formation are: (−3383.4 and −3147) kJ · mol−1. The former one is in better agreement with literature data. 相似文献