全文获取类型
收费全文 | 130篇 |
免费 | 2篇 |
国内免费 | 13篇 |
专业分类
化学 | 136篇 |
力学 | 4篇 |
综合类 | 1篇 |
物理学 | 4篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 9篇 |
2008年 | 9篇 |
2007年 | 15篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有145条查询结果,搜索用时 15 毫秒
31.
《Journal of Coordination Chemistry》2012,65(11):1879-1886
A new energetic complex, Pb(ATZ)(phen)2·3H2O (1) (ATZ = 5,5′-azotetrazolate), was synthesized and characterized by single crystal X-ray diffraction. Crystal data: monoclinic, P2(1)/n space group, a = 8.4545(1) Å, b = 25.846(2)Å, c = 13.096(2)Å, and β = 102.873(2)°. In addition, elemental analysis, IR, and thermogravimetric analysis are presented. Furthermore, the complex was also explored as an additive to promote thermal decomposition of ammonium perchlorate. 相似文献
32.
The industrial porous co-polymers and resins in the form of spherical granules include three main matrices which serve as
the basis of the large-scale production of ion-exchange materials: styrene/divinylbenzene, vinylpyridine/divinylbenzene and
acrylonitrile/divinylbenzene. Complex thermal methods (TG, DTG and DTA) were used to study the carbonization processes of
various industrial products utilized as starting materials for the preparation of synthetic active carbons. The DTG results,
the thermal effects observed during the programmed heating of samples, and the mass-spectrometric and IR-spectroscopic data
up to 800°C provided a picture of a multi-stage carbonization process. This includes the removal of moisture from the polymer
matrices, the primary cross-linking of the chains, their aromatization and condensation due to the cross-linking of polynuclear
structures, and the removal of ‘excess carbon’ as simple molecules and free radicals of hydrocarbon type. The results promoted
the choice of the optimal regimes in which to carryout the isothermal pyrolysis of various polymer matrices and preliminary
chemical modifications to increase the yields on carbon and to prepare synthetic active carbons such as those of SCN, SCAN
and SCS types. General schemes were proposed for the chemical reactions accompanying the carbonization process for these polymer
matrices.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
33.
Judit Varga Á. Fudala J. Halász I. Kiricsi 《Journal of Thermal Analysis and Calorimetry》1996,47(2):391-397
The solid-state ion-exchange procedures of zeolites with Cu2+, Ni2+, Fe2+ and Co2+ salts can be resulted in prosperous catalysts for NO decomposition. Reactions taking place in solid-state between four transition metal cholirides and H-ZS-5 zeolite were investigated by means of a derivatograph. The results showed that irreversible consumption of surface -OH groups occurred with simultaneous bonding of the transition metal in the zeolite channel structure. 相似文献
34.
Thermal analysis of crude oils and comparison with SIMDIST and TBP distillation data 总被引:1,自引:0,他引:1
M. A. Ali M. A. B. Siddiqui S. M. J. Zaidi 《Journal of Thermal Analysis and Calorimetry》1998,51(1):307-319
Four commercial Saudi Arabian crude oils were characterized by thermogravimetry (TG) and differential thermal analysis (DTA).
These crude oils, Arab Berri (AB), Arab Light (AL), Arab Medium (AM) and Arab Heavy (AH), were also subjected to the traditionally
employed true boiling point (TBP) distillation and simulated distillation (SIMDIST). The TG/DTA data show that the hydrocarbons
present in these crude oils fall into four groups: the volatiles, the low molecular weight, the medium molecular weight and
the high molecular weight compounds. These four types of hydrocarbons were observed to display certain trends, such that the
volatile and low molecular weight hydrocarbons increased, while the medium and high molecular weight hydrocarbons decreased
with the lightness of the crude. The volatile contents of AB, AL, AM and AH crude oils up to 280°C were 50.1, 42.2, 42.3 and
38.5 mass percent, respectively. This confirms that AB is the lightest of these crude oils with maximum volatile content.
The mass percentage loss from the TG results is in good agreement with the percentage distilled from TBP (ASTM D 2892) and
SIMDIST. During evaporation, the TG mass loss follows a similar trend to those of the TBP and SIMDIST results and thus behaves
like distillation. During the oxidative degradation, the TG curve shows a higher mass loss as compared to the distillation
data. The higher deviation of the TG mass loss and percentage distilled at the higher-temperature end of the curve may be
attributed to the higher content of asphaltenes and carbonaceous material present in AH as compared to the AB crude oil. At
around 200°C, the TG mass loss curve intersects the TBP and SIMDIST curves and shows a derivation from distillation behaviour.
This intersection temperature of the TG and distillation curves is observed to decrease with the heaviness of the crude and
can be an indication of the onset of thermal degradation of hydrocarbons present in the crude oil. On the whole, the TG data
closely resemble the distillation results. 相似文献
35.
M. Montazerozohori S.A. Musavi A. Masoudi-asl H. Mohammadi R. Naghiha A. Assoud 《Arabian Journal of Chemistry》2019,12(7):1463-1473
Three new four coordinated zinc(II) complexes have been synthesized and characterized by IR, UV, elemental analysis, 1H and 13C NMR and X-ray single crystal analysis. The elemental analyses of the complexes are in agreement with the general formula of ZnLX2 wherein L = Schiff base ligand and X = Cl?, Br? and I?. Low molar conductivities in DMF indicated non-electrolyte character of all complexes. Spectroscopic studies well confirmed the coordination via azomethine nitrogens of the ligand to zinc ion. The single crystal X-ray analysis shows that ZnLBr2 crystallizes in the triclinic crystal system with space group . It contains two crystallographically independent molecules noted as A and B, with both Zn1A and Zn1B being almost in perfect tetrahedral environments (τ4 = 0.94 for Zn1A and τ4 = 0.93 for Zn1B). A detailed structural analysis shows that there are three non-classical hydrogen bondings of C–H…Br in the structure. Various C–H…π and C–H…Br interactions play an important role in stabilizing the molecular structure and then give rise to a 3D supramolecular structure of the ZnLBr2 complex. After characterization, the Schiff base and its complexes were screened in vitro for their antibacterial and antifungal activities by disk diffusion technique. Also the ability of the complexes for DNA cleavage was studied by agarose gel electrophoresis method. Finally, thermal behavior of the complexes has been studied by thermo-gravimetry and then some activation kinetics parameters of decomposition steps were evaluated based on TG/DTG plots. 相似文献
36.
Drábik M. Gáliková L. Varshney K. G. Quraishi M. A. 《Journal of Thermal Analysis and Calorimetry》2004,76(1):91-96
The applicability of MDF synthesis procedure, the coincidence of the interfacial cross-linking and the moisture resistance
of MDF-related mixes based on two industrial Portland cements (CEM I, CEM II) and poly-P are reported. The knowledge of the
moisture resistance of synthesized material is of paramount importance; two independent experimental methods confirmed that
the moisture resistance of MDF cements based on CEM I (or CEM II) with 5% of poly-P achieves sufficient levels at 50% RH and
at ambient values of RH. The results of thermal analysis are directly related to the former knowledge on the appearance and
role of cross-links in the interfacial zone of MDF cements.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
37.
神木煤有机显微组分的结构特征与热转化性质的关系 总被引:6,自引:6,他引:6
通过手选和重液浮选分离相结合的方法,从神木煤中分离得到了纯度较高的镜质组和惰质组,并对其进行元素分析、FT-IR、13CNMR和TG/DTG等表征分析。结果表明,神木煤镜质组和惰质组的最佳分离密度为1.320 g/cm3~1.324 g/cm3和1.378 g/cm3~1.382 g/cm3,此时分离纯度分别为97.55%和96.90%。镜质组有较高的H含量,较低的芳香度0.51和数量较多的氢键;惰质组有较高的碳含量,较高的芳香度0.76,原煤的芳香度介于两者之间为0.68。FT-IR分析表明,镜质组比惰质组有较多的氢键,脂肪氢含量和较少的Har/Hal比。随温度增加,镜质组和惰质组的芳香氢含量和Har/Hal比增加,而脂肪氢含量减少。相同温度下,惰质组的Har/Hal比始终高于镜质组。TG/DTG分析表明惰质组比镜质组有较高的热稳定性,原煤的热稳定性介于两者之间,在相同的Har/Hal比时镜质组中剩余挥发分比惰质组的少,反映出惰质组的组成(较高的芳香度和较低的脂肪氢含量)对热稳定性的影响。 相似文献
38.
Summary A series of calcium silicate hydrate (C-S-H)-polymer nanocomposite (C-S-HPN) materials were prepared by incorporating poly(vinyl
alcohol) (PVA) into the inorganic layers of C-S-H during precipitation of quasicrystalline C-S-H from aqueous solution. The
as synthesized C-S-HPN materials were characterized by Fourier-transform infrared photoacoustic (FTIRPAS) spectroscopy, X-ray
diffraction (XRD), scanning electron microscopy/energy dispersed spectroscopy (SEM/EDS), thermogravimetric analysis (TG),
differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The XRD peaks of C-S-HPN materials suggest
the intermediate organizations presenting both intercalation of PVA and exfoliation of C-S-H. The SEM micrographs of C-S-H,
PVA and C-S-HPN materials with different PVA contents exhibit the significant differences in their morphologies. Effects of
the material compositions on the thermal stability of a series of C-S-HPN materials along with PVA and C-S-H were studied
by TG, DTG and DSC. Three significant decomposition temperature ranges were observed in the TG curves of all C-S-HPN materials. 相似文献
39.
A potential bacterial carrier for bioremediation 总被引:1,自引:0,他引:1
C. Elliott Z. Ye S. C. Mojumdar M. T. Saleh 《Journal of Thermal Analysis and Calorimetry》2007,90(3):707-711
One of the limiting factors to the effectiveness of biostimulation and bioremediation is the loss of inoculated material from
the site. This can occur by a number of pathways, but is particularly problematic in open water systems where the inoculated
material is simply lost in the water. It is desirable to develop new material, a matrix, within which bacteria and/or biostimulants
can be incorporated.
We have investigated the basic physical properties of insoluble potato starch to eventually evaluate its use as such a matrix.
Insoluble starch fibers were prepared from white potato (Solanum tuberosum) and sweet potato (Ipomoea batatas) and were compared for their melting temperature by DSC and their ability to bind/aggregate bacteria. The DSC curves for
white and sweet potato showed that the melting temperature is 127.34 and 133.05°C for white and sweet potato fibers, respectively.
The TG curves for white and sweet potato starches exhibited one main mass loss step corresponding to the DTG peak temperature
at 323.39 and 346.93°C, respectively. The two types of fibers, however, showed different binding/aggregation capacities for
bacteria, with white potato approximately twice as many cells of Burkholderia cepacia (22.6 billion/g) as cells of Pseudomonas putida. The reverse was true for fibers from sweet potato, binding twice as many cells of Pseudomonas putida (23 billion/g) as cells of Burkholderia cepacia. 相似文献
40.