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排序方式: 共有56条查询结果,搜索用时 15 毫秒
1.
分析了在“用板式电势差计测量电池的电动势和内阻”实验中 ,由于待测干电池的电动势和内阻在实验过程中均不为恒定值而引起的误差 ,依据电化学理论和电阻构成解释了实验现象 ,并给出了实验改进方案 . 相似文献
2.
Lakshmi N. Roy Rabindra N. Roy Cole E. Denton Sean R. LeNoue Chandra N. Roy Shahaf Ashkenazi Thomas B. Williams Daniel R. Church Michael S. Fuge Kartik N. Sreepada 《Journal of solution chemistry》2006,35(4):605-624
The values of the second dissociation constant, K
2, and related thermodynamic quantities of the ampholyte bis[(2-hydroxyethyl)amino]acetic acid (BICINE) have been determined at temperatures from 5 to 55 ∘C. The pH values of six equimolal buffer solutions, and four buffer solutions having ionic strengths (I = 0.16 mol⋅kg−1) similar to those in blood plasma, have been evaluated at 12 temperatures from 5 to 55 ∘C using the Bates–Guggenheim convention. The liquid junction potentials (E
j
) between the buffer solutions of BICINE and saturated KCl solution of the calomel electrode at 25 and 37 ∘C have been estimated by measurement with a flowing junction cell. These values of E
j
have been used to ascertain the operational pH values at 25 and 37 ∘C. The pK
2 values at 25 and 37 ∘C are 8.333 and 8.156, respectively. The thermodynamic quantities associated with the second acid dissociation have been calculated from the values of pK
2 as a function of temperature. The zwitterionic buffer BICINE was shown to be useful as a pH standard in the region close to that of blood serum. 相似文献
3.
The hydrolysis of chromate ion was studied potentiometrically in a concentration cell fitted with hydrogen electrodes by titrating basic NaCl–Na2CrO4 solutions with standardized HCl against a NaOH reference solution. The temperature was varied from 25 to 175°C at 25° intervals at the following ionic strengths (I): 0.1140, 0.2346, 0.5337, 0.9988, 2.940, and 5.239 (NaCl). Depending on the ionic strength, the molality of total chromium was varied from 0.001 to 0.100. The resulting titration curves could be resolved best in terms of three equilibria involving the formation of HCrO
4
–
(aq), Cr2O3– (aq), and CrO3Cl– (aq). The equilibrium quotients for all three reactions were fitted as a function of temperature and ionic strength, and the molal thermodynamic parameters that were computed from these relationships are tabulated at specific ionic strengths over the experimental temperature range. 相似文献
4.
This paper reports our results for the direct experimental determination of the equilibrium constant for the hydrogen-isotope-exchange
reaction, 1/2D2(g)+HCl(hexOH)=1/2H2(g)+DCl(hexOD), where hexOH isn-hexanol and hexOD isn-hexanol with deuterium substitution in the alcohol function. The reaction was studied in electrochemical double cells without
liquid junction for which the net cell reaction is the above isotope-exchange reaction. The experimentally determined value
of ε° (296.0°K) for this cell is 4.03±0.95 mV (strong electrolyte standard states, mole-fraction composition scale); the value
of the equilibrium constant for the reaction is 1.17±0.05. The contributions of isotope-exchange and transfer effects to the
magnitude of the standard Gibbs energy change for the above reaction and for the analogous reaction 1/2D2(g)+HCl(aq)=DCl(daq)+1/2H2(g) are considered. Our results support the conclusion of Heinzinger and Weston that the formulation of the solvated proton
in water as H3O+, as opposed to H9O4
+, is sufficient for the interpretation of the thermodynamics of hydrogen-isotope-exchange reactions in water. We also find
that the formulation of the solvated proton inn-hexanol as ROH
2
+
is sufficient for the interpretation of our results on the thermodynamics of hydrogen-isotope-exchange inn-hexanol. 相似文献
5.
Rabindra N. Roy Jill Cramer Victoria Randon Demara Willard Jennifer L. Walter William S. Good Amanda Kilker Lakshmi N. Roy 《Journal of solution chemistry》1998,27(5):425-434
The second acidic dissociation constants pK
2 of the ampholyte N-(2-hydroxyethyl) piperazine-N-2-hydroxypropanesulfonic acid (HEPPSO) have been determined at seven temperatures from 5 to 55°C from emf measurements utilizing hydrogen and silver–silver chloride cells without liquid junction. The thermodynamic quantities, G°, H°,S°, and C
p
o
have been calculated from the temperature coefficient of pK
2. At 25°C, the pK
2 = 8.042 and at 37°C, pK
2 = 7.876; hence, buffer solutions of HEPPSO and NaHEPPSOate are important for pH control in the region close to that of clinical fluids (blood serum). Conventional pH values from 5 to 55°C as well as those obtained from liquid junction correction at 25 and 37°C have been reported for three buffer solutions with the compositions (molality scale): (1) equimolal mixture of HEPPSO (0.04 m) + NaHEPPSOate (0.04 m) + NaCl (0.12 m); (2) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m); and (3) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m) + NaCl (0.08 m). 相似文献
6.
动生、感生电动势与法拉第电磁感应定律等价性的研究 总被引:1,自引:0,他引:1
法拉第电磁感应定律与动生电动势、感生电动势之和是完全等价的。本文通过实例证明,等价是有条件的。当回路中存在大块导体时,则不等价。 相似文献
7.
R. E. Verrall 《Journal of solution chemistry》1975,4(4):319-329
Precise values of the activity coefficients of aqueous ammonium chloride solutions at 25°C determined from emf measurements of cells with transference are reported for the concentration range 0 to 0.2m. The results show no anomalous behavior with respect to the Debye-Hückel limiting law. An interpretation of excess thermodynamic functions of potassium and ammonium chloride solutions is made in terms of ionic influences on solvent structure. The relative order of activity coefficients for the R
4
NCl series up to 0.1m is shown to be (NH
4
Cl)>(Me
4
NCl)>(Et
4
NCl)>(n-Bu
4
NCl). 相似文献
8.
In this paper it is shown by using the Clifford algebra formalism that the usual Lorentz transformations of the three-dimensional (3D) vectors of the electric and magnetic fields E and B (which will be named as standard transformations (ST)) are different than the Lorentz transformations (LT) of well-defined quantities from the 4D spacetime. This difference between the ST and the LT is obtained regardless of the used algebraic objects (1-vectors or bivectors) for the representation of the electric and magnetic fields in the usual observer dependent decompositions of F. The LT correctly transform the whole 4D quantity, e.g., Ef : F · γ0, whereas the ST are the result of the application of the LT only to the part of Ef, i.e., to F, but leaving γ0 unchanged. The new decompositions of F in terms of 4D quantities that are defined without reference frames, i.e., the absolute quantities, are introduced and discussed. It is shown that the LT of the 4D quantities representing electric and magnetic fields correctly describe the motional electromotive force (emf) for all relatively moving inertial observers, whereas it is not the case with the ST of the 3D E and B. 相似文献
9.
The thermodynamic properties of the liquid Ag-Sb alloys were determined using solid oxide galvanic cells with zirconia electrolyte. The emfs of the cells:
10.
A new experimental approach is proposed for the evaluation of liquid junction potentials and single ion activities. Neither of these quantities can be experimentally measured without assumption. Furthermore, they are concentration dependent but without clearly defined functional relationships. Thus, a given assumption may be satisfactory to obtain these quantities at a given concentration, but will fail at another concentration. It is the intent of this paper to establish a functional relationship between the ratio of activity coefficients and the ionic strength, through which the liquid junction potentials may be computed, as well as the pH values at moderate ionic strengths (<1.0 m). Experimental results are presented and uncertainties are discussed. 相似文献