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排序方式: 共有68条查询结果,搜索用时 46 毫秒
1.
K. Raha Mrs P. S. Makashir E. M. Kurian 《Journal of Thermal Analysis and Calorimetry》1989,35(4):1173-1179
The kinetics of the initial stage of thermal decomposition of N-2,4,6 tetranitro-N-methyl aniline (tetryl) in condensed state has been investigated by high temperature infrared spectroscopy (IR) in conjunction with pyrolysis gas analysis and thermogravimetry (TG). The decomposition in KBr matrix in the temperature range of 131 to 145 °C shows rapid decrease in the N-NO2 band intensity as compared to the C-NO2 band. Decomposition products in the initial stage show mainly NO2 gas and picric acid. The studies show that the initial stage of decomposition of tetryl occurs by the rupture of the N-NO2 bond and the energy of activation for this process is 177 kJ/mol.
Zusammenfassung Mittels Hochtemperatur-IR-Spektroskopie wurde in Verbindung mit Pyrolysengasanalyse und Thermogravimetrie (TG) die Kinetik des einleitenden Schrittes der thermischen Zersetzung von N-2,4,6-Tetranitro-N-Methylanilin (Tetryl) im kondensierten Zustand untersucht. Die Zersetzung in einer KBr-Matrix im Temperaturbereich von 131–145 °C äußert sich in einem schnellen Abnehmen der Intensität der N-NO2 Bande bezogen auf die der C-NO2 Bande. Zersetzungsprodukte des einleitenden Schrittes sind hauptsächlich NO2 Gas und Pikrinsäure. Die Untersuchungen zeigten, daß der einleitende Schritt der Zersetzung von Tetryl die Spaltung der N-NO2 Bindung ist. Die Aktivierungsenergie für diesen Prozess beträgt 177 kJ/mol.
N-2,4,6-N- () , . 131–145 °C N-NO2 C-NO2. . , N-NO2, 177 /.相似文献
2.
3.
Cuprous oxide (Cu2O) nanorods doped with iron impurities have been synthesized by the polyol method using sodium dodecyl sulfate as the surfactant. The X-ray diffraction measurement reveals the pure phase of simple cubic Cu2O and the electron microscopy displays its one dimensional morphology. Ferromagnetism was observed at room temperature in the magnetic measurements of the doped samples while undoped sample exhibits only diamagnetism. Room temperature Mössbauer spectra for the samples exhibited only doublets but no sextet, which corresponds to the presence of paramagnetic iron sites. As magnetic moment contribution of the doped ions was insignificant for the observed magnetism, ferromagnetic property in the doped samples could have been originated from the defects as cation vacancies. Existence of the defects was supported by the room temperature photoluminescence spectra of the doped samples in reference to the undoped sample. 相似文献
4.
Pious Kurian Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》2002,40(9):1209-1217
Novel tricontinuous membranes consisting of well‐defined hydrophilic poly(ethylene glycol) (PEG) and lipophilic polyisobutylene (PIB) segments crosslinked by oxyphilic poly(pentamethylcyclopentasiloxane) (PD5) domains have been synthesized and characterized. Tricontinuity arises because the three membrane constituents—PEG, PIB, and PD5—are mutually incompatible and give rise to three independent cocontinuous phases (channels). The continuous PEG segments impart swelling in water (hydrogel character), the rubbery PIB moieties provide strength, and the PD5 domains provide crosslinking and enhanced O2 permeability. The synthesis involves the random cohydrosilation of various lengths (number‐average molecular weights) of α,ω‐diallyl‐PEG and α,ω‐diallyl‐PIB segments by pentamethylcyclopentasiloxane (D5H) followed by water‐mediated oxidation of the SiH groups of the D5H to SiOH groups, which immediately polycondense to PD5 domains. Membranes containing about equal amounts of PEG, PIB, and PD5 give rise to tricontinuous morphologies that allow the simultaneous permeation of water, heptane, and oxygen via three cocontinuous channels. The number‐average molecular weight of the PEG segment, that is, the number‐average molecular weight of the hydrophilic segment between two PD5 crosslink sites, determines the dimensions (pore sizes) of the channels through which water can permeate. A method has been developed for studying the oxygen permeability of membranes. The microarchitecture of the membranes has been investigated with selective swelling experiments and Fourier transform infrared spectroscopy, their mechanical properties have been examined in the water‐swollen state with Instron measurements, and their bulk morphologies and thermal degradation have been determined with differential scanning calorimetry and thermogravimetric analysis, respectively. The findings have been interpreted in terms of phase‐separated PEG, PIB, and PD5 microdomains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1209–1217, 2002 相似文献
5.
D. K. Chakraborty J. Kurian J. P. Kennedy W. L. Mattice 《Colloid and polymer science》1991,269(8):807-811
The steady-state fluorescence emission spectrum of poly(pentafluorostyrene) in dilute fluid solution shows no excimer emission. An atomic level modeling study explains why this polymer cannot form an excimer. Repulsive Coulombic interactions prohibit the attainment of the extensive overlap of the two rings in the classic face-to-face sandwich conformation of a singlet excimer. 相似文献
6.
Achamma Kurian C V Bindhu S S Harilal Riju C Issac V P N Nampoori C P G Vallabhan 《Pramana》1994,43(5):401-406
A simple method based on laser beam deflection to study the variation of diffusion coefficient with concentration in a solution
is presented. When a properly fanned out laser beam is passed through a rectangular cell filled with solution having concentration
gradient, the emergent beam traces out a curved pattern on a screen. By taking measurements on the pattern at different concentrations,
the variation of diffusion coefficient with concentration can be determined. 相似文献
7.
The freejet characteristics of radially lobed nozzles were studied experimentally. Schlieren photographs of the freejets revealed that the lobes of the nozzles gave rise to alternate expansion-compression regions. For two of the lobed nozzles the potential core was reduced by a factor of three relative to the conical nozzle tested. The jet spread and the shear layer thickness of the lobed nozzles were considerably higher than those for the conical nozzle. The jet width and the shear layer thickness were higher in the major plane; however, the shear layer growth rate was higher in the minor plane of the lobed nozzles. Jet axial thrust measurements revealed a thrust loss of 14% for two of the lobed nozzles tested. 相似文献
8.
9.
E. M. Kurian 《Journal of Thermal Analysis and Calorimetry》1989,35(4):1111-1117
The application of thermal analysis in the study of reaction kinetics and reaction mechanisms in combination with presently available powerful analytical tools, in the sphere of materials with particular reference to high energy materials is presented and discussed. Also an attempt has been made to correlate the kinetic data obtained by TA with the performance characteristics, for some important materials.
Zusammenfassung Es wird die Anwendung der Thermoanalyse bei der Untersuchung der Reaktionskinetik und des Reaktionsmechanismus in Zusammenwirkung mit den gegenwärtig zur Verfügung stehenden leistungsfähigen analytischen Werkzeugen auf dem Gebiet von Materialien mit speziellem Bezug auf energiereiche Stoffe dargestellt Und besprochen. Es wurde auch versucht, die durch TA erhaltenen kinetischen Daten einiger wichtiger Stoffe mit deren Leistungskenndaten in Beziehung zu stellen.
. , , .相似文献
10.
Chandu Venugopal M. J. Kurian E. Savithri Devi P. J. Jessy C. P. Anilkumar G. Renuka 《Indian Journal of Physics》2010,84(3):319-324
The dispersion characteristics of low-frequency electromagnetic waves are studied in a plasma containing hydrogen ions and
positively and negatively charged oxygen ions and electrons. This composition of the plasma approximates very well the coma
of comet Halley where many heavy ions have been observed in appreciable numbers. The excitation of these waves results from
the relative motion between the protons and the heavy ions, which are considered unmagnetised and, therefore, may act like
a beam. We find that the wave growth increases with increasing heavy ion densities, beam velocities and propagation angles. 相似文献