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71.
72.
73.
吸附伏安法测定表面活性剂的临界胶束浓度 总被引:2,自引:0,他引:2
以易溶于有机溶剂,微溶于水的氧化-还原指示剂中性红为探针,用吸附伏安法测定了阴离子表面活性剂的临界胶束浓度。测量的基本原理是:存在于表面活性剂溶液中的微量中性红在悬汞电极上的吸附伏安峰电流对表面活性剂浓度的曲线在临界胶束浓度处有一拐点。 相似文献
74.
M. A. Sanz N. Granizo M. Gradzielski M. M. Rodrigo M. Valiente 《Colloid and polymer science》2005,283(6):646-652
We have made a comparative study between the micellar regions of the octyl -d-glucoside (OG)–tetraethylene glycol monododecyl ether and the OG–poly(ethylene glycol) 20,000 systems by means of surface tension and viscosimetric measurements. The incorporation of the tetraethylene glycol monododecyl ether nonionic surfactant in the OG micelles decreases the critical micelle concentration, whereas the presence of polymer increases it. The nonionic surfactant mixture exhibits nonideal mixing behaviour. The data fit to Rubinghs treatment with a value of –5.1, which implies a modest attraction between both surfactants. The surfactant–poly(ethylene glycol) 20,000 system does not form mixed micelles. The incorporation of polymer increases the critical micelle concentration of the surfactant. The viscosity for the surfactant–polymer system is higher than that for the pure polymer, demonstrating a surfactant-induced structuring. 相似文献
75.
Peter Scharfenberg 《Theoretical chemistry accounts》1980,58(1):73-79
A simple classification scheme is proposed for critical points, based only on rankr and signatures of the (n,n)-matrixG of harmonic force constants. The determination ofr ands, e.g. by the well-known factorizationG=L
T
gL (L: triangular matrix,g: diagonal matrix), has several theoretical as well as practical (computational) advantages over the inspection of eigenvalues ofG, so far used in quantum chemistry. The eigenvalues are sufficient butnot necessary for a classification whereas rank and signature are the only necessary and sufficient prerequisites for solving the task. For the purpose of presenting a working example, by calculating only a 2×2 torque constant matrix, it is shown that the coplanar ethylbenzene is unstable in the CNDO/2 picture. 相似文献
76.
77.
Mariana Ramos-Estrada Gustavo A. Iglesias-Silva Kenneth R. Hall F. Kohler 《Fluid Phase Equilibria》2006,240(2):179-185
We use the Clausius–Clapeyron equation to calculate third virial coefficients at low reduced temperatures. This procedure gives an alternative to predict third virial coefficients in a region where the third virial coefficient is difficult to measure. We compare the results of this method with published third virial coefficient data. Calculated third virial coefficients have average percentage deviations within 5% of the experimental values at reduced temperatures between 0.8 and 1.0. 相似文献
78.
Summary. Two main types of binary systems with distinctive solubility behavior under sub- and supercritical conditions were used to
subdivide ternary water-salt systems into three classes. Characteristic features of solubility behavior and phase equilibria
in ternary water-salt systems of each class at temperatures above 200°C are discussed on the basis of available experimental
data and some conclusions obtained as a result of theoretical derivation of fluid and complete phase diagrams.
Corresponding author. E-mail: Valyashko@IGIC.RAS.RU
Received September 25, 2002; accepted (revised) November 28, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. H. Gamsjaeger on the occasion of his 70th birthday anniversary 相似文献
79.
M. Hoorfar M.A. Kurz A.W. Neumann 《Colloids and surfaces. A, Physicochemical and engineering aspects》2005,260(1-3):277-285
A quantitative criterion called “shape parameter” to evaluate the quality of surface tension measurement of Axisymmetric Drop Shape Analysis (ADSA) is presented. ADSA is a powerful technique for the measurement of interfacial tensions and contact angles of pendant drops, sessile drops, and bubbles. Despite the general success of ADSA, deficient results may be obtained for drops close to spherical shape. Therefore, the “shape parameter” was used to determine the range of drop shapes in which ADSA succeeds or fails. The “shape parameter” is a dimensionless parameter that expresses quantitatively the difference in shape between a given experimental profile and an inscribed circle. The surface tension measurements of ADSA were evaluated for both pendant drop and constrained sessile drop configurations using the shape parameter. Different shapes of the pendant drop were studied using different sizes and materials of holders. For each drop configuration, a “critical shape parameter” was defined based on the minimum value of the shape parameter that guarantees an error of less than ±0.1 mJ/m2. Furthermore, the effects of the type of liquid and constellation on the “critical shape parameter” were studied. 相似文献
80.
Tsirelson Vladimir Abramov Yury Zavodnik Valery Stash Adam Belokoneva Elena Stahn Jochen Pietsch Ullrich Feil Dirk 《Structural chemistry》1998,9(4):249-254
The critical points in the model electron density distributions of LiF, NaF, NaCl, and MgO crystals, constructed from accurate X-ray diffraction data, are determined. For LiF and MgO they are compared with those obtained from a Hartree–Fock electron density calculation. Both experiment and theory show the same type of critical points on the bond lines. The topological features in areas between structural units, where the electron density is low and near-uniform, turn out to be model dependent and cannot be established well with the data available. Topological analysis of procrystals (hypothetical systems consisting of spherical atoms or ions placed on the same sites as atoms in real crystal) show that (3, –1) critical points, usually connected with bonding interaction, are observed on interatomic lines in these nonbonded systems as well. 相似文献