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11.
12.
T. Kleps M. Piaskiewicz W. Parasiewicz 《Journal of Thermal Analysis and Calorimetry》2000,60(1):271-277
Thermogravimetry was employed to study the changes occurring in rubber vulcanizates during devulcanization carried out by
microwave treatment, a new promising method of recycling rubber waste. The thermogravimetric parameters T
i , T
5 and T
p and the compositions of devulcanizates in comparison with vulcanizates were determined. The results obtained allowed estimation
of the degree of destruction of the polymer chains in response to microwave treatment and permitted establishment of the most
advantageous conditions of devulcanization in order to obtain the best properties of rubber devulcanizates for reuse in rubber
processing.
The results demonstrated that thermogravimetry is a very useful method for investigation and control of the microwave devulcanization
process.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
J. Zsakó I. Ganescu Cs. Várhelyi L. Chirigiu 《Journal of Thermal Analysis and Calorimetry》1997,48(2):367-371
Thermal decomposition of 6 complexes of the type AH[Cr(NCS)4 (am)2]· nH2O is studied with derivatograph. The formation of Cr(NCS)3 as a labile intermediate is presumed. For some decomposition stages kinetic parameters are derived. The kinetic compensation effect is discussed. 相似文献
14.
The author gives a detailed survey on thermogravimetric investigations under quasi-isothermal — quasi-isobaric conditions (Q-TG). According to the principle of the technique the heating of the sample is governed by the transformation itself according to the feed-back principle in a way that the transformations should take place at a strictly constant rate, slower by orders of magnitude than in the case of the conventional techniques. Due to this, the transformations take place under ideal conditions, near to physico-chemical requirements.Based on the obtained advantageous results further methods were elaborated, like thermo-dilatometry (Q-TD), evolved gas analysis (Q-EGA) and microdistillation under quasi-isothermal conditions.The second part of the present review deals with DTA and DSC techniques under quasi-isothermal conditions elaborated recentlyThis revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
15.
For many applications poly(styrene) must
be treated to reduce its flammability. This is usually done by incorporating
a flame retardant additive, usually an organohalogen compound, into the formulation
as the polymer is being processed. A potentially very efficient way of introducing
flame retardance would be to incorporate a suitable structural unit directly
into the polymer. This can be done by using 2,4,4,5,5-pentaphenyl-1,3,2-dioxaphospholane
as an initiator for styrene polymerization. The strained carbon–carbon
bond of the phospholane undergoes homolysis at moderate temperatures to generate
a diradical which initiates polymerization. The resulting polymer contains
an O–P–O unit in the mainchain. Thermogravimetry indicates that
the thermal stability of the polymer is quite comparable to that of poly(styrene)
generated by conventional methods. 相似文献
16.
A kinetic study of the crystallization of poly(ethylene oxide) (PEO) and of a blend of PEO+poly(bisphenol A-co-epichlorohydrin)
(PBE) was performed by using DSC in a non-isothermal program at constant cooling rates. The curves obtained were analyzed
by the Kissinger, Ozawa and Friedman methods, with determination of the kinetic parameters in each case. As a consequence
of the presence of PBE, the kinetic parameters were altered, leading to the conclusion that PBE has some influence on the
crystallization of PEO, modifying its mechanism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Dynamic thermal analysis of solid-state reactions 总被引:2,自引:0,他引:2
There are many reactions of interest in which one or more of the reactants belong to some solid phases. Modern thermoanalytical instruments can conveniently provide reaction kinetic data of high precision and accuracy, from which the underlying activation energyE may be derived in principle. Unfortunately, no best method yet exists for the derivation when the data have been collected with a programmed linear increase in sample temperature, unlike the case of isothermal measurements, which however suffer from experimental limitations [1]. Here we propose a method for extractingE from non-isothermal data, that promises general validity. 相似文献
18.
Thanner H. Krempl P. W. Selic R. Wallnöfer W. Worsch P. M. 《Journal of Thermal Analysis and Calorimetry》2003,71(1):53-59
Quartz-homeotypic gallium (ortho-) phosphate, GaPO4, is of special interest for resonator applications asking for temperature compensated cuts with higher electro-mechanical coupling than quartz and operational temperatures up to 970°C. The crystal microbalance technique, well known for quartz (QCM) which can be used only at moderate temperatures, can now be extended to much higher temperatures using GaPO4 crystals, benefiting from all three advantages mentioned above. Two different experiments were done to demonstrate the advantages of a crystal microbalance based on GaPO4. First, the GaPO4 resonator was used for film thickness determination and compared with a commercial QCM. This experiment demonstrated that the measuring range can be extended by using GaPO4 resonators instead of quartz. The second experiment demonstrates the possibility for thermogravimetric analysis up to 720°C by using a new concept for resonator mounting.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
19.
Vlase T. Vlase G. Chiriac A. Doca N. 《Journal of Thermal Analysis and Calorimetry》2003,72(3):839-845
The thermal decomposition in non-isothermal conditions of formates, acetates, propionates and butyrates of Mn, Co, Zn, Cd,
Eu, Sm and Ni was studied. The observed compensation effect allows us to calculate the isokinetic temperature. A selective
activation mechanism was suggested. This leads to a good agreement between kinetic and spectroscopic data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Non-isothermal short-range-order kinetics of binary alloys as influenced by solute-vacancy complexes
A model describing the roles of bound and unbound vacancies is proposed in order to predict defect decay and short-range-order
kinetics of quenched binary alloys during linear heating experiments. This is an alternative treatment of a previous approach.
The model has been applied to the differential scanning calorimetry (DSC) curves of Cu-5 at.% Zn quenched from different temperatures.
An expression to calculate the activation energy for migration of solute-vacancy complexes was also developed which make use
of DSC trace data. A value of 89.12±0.32 kJ mol-1 was obtained for the above alloy. The relative contribution of bound and unbound vacancies to partition of effective activation
energy corresponding to the ordering process as influenced by quenching temperature was also assessed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献