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991.
Pressure induced line shift and line mixing parameters have been measured for 66 rovibrational lines in the ν4 band and for 10 lines in the 2ν2 band of NH3 perturbed by H2 and Ar at room temperature (T = 296 K). These lines with J values ranging from 2 to 10 are located in the spectral range 1450-1600 cm−1. Experiments were made with a high-resolution Fourier transform spectrometer. The line shifts and line mixing parameters have been derived from the non-linear least-square multi-pressure fitting technique. The shift coefficients are compared with those calculated from the Robert-Bonamy formalism (RB). The results are generally in satisfactory agreement with the experimental data. 相似文献
992.
We give a summary on the recent development of chaos theory in topological dynamics,focusing on Li–Yorke chaos, Devaney chaos, distributional chaos, positive topological entropy, weakly mixing sets and so on, and their relationships. 相似文献
993.
Nicolas Privault 《Stochastics An International Journal of Probability and Stochastic Processes》2016,88(3):321-335
We derive sufficient conditions for the mixing of all orders of interacting transformations of a spatial Poisson point process, under a zero-type condition in probability and a generalized adaptedness condition. This extends a classical result in the case of deterministic transformations of Poisson measures. The approach relies on moment and covariance identities for Poisson stochastic integrals with random integrands. 相似文献
994.
The crystal structure of the quaternary compound semiconductor Cu2ZnGeSe4 (CZGSe) was investigated by the complementary use of neutron diffraction, and Raman spectroscopy. The powder sample, which resulting from wavelength dispersive X-ray spectroscopy (WDX) turned out to be single phase Cu-rich CZGSe, was synthesized by solid state reaction of the pure elements in an evacuated silica tube at 700 °C. Raman spectroscopy confirmed the homogeneity and phase purity of the sample, in addition, the kesterite type structure was suggested. Rietveld analysis of the neutron diffraction data confirmed that the compound crystallizes in the tetragonal kesterite type structure. The refined site occupancy factors were used to determine the average neutron scattering lengths of the cation sites, giving insights into cation distribution and finally point defect types. Thus it has been shown, that additional to the CuZn-ZnCu anti-site defects in the lattice planes at z=¼ and ¾ (Cu-Zn disorder) also the off-stoichiometry type related point defects like Cui and CuZn occur in Cu-rich CZGSe. 相似文献
995.
Dimple Sharma J.S. Yadav Satish Kumar K.C. Singh V.K. Sharma 《Thermochimica Acta》2008,471(1-2):74-79
Molar excess volumes, VE, molar excess enthalpies, HE, and speeds of sound data, u, of chloroform (i) + aniline or o-toluidine (j) binary mixtures have been measured as a function of composition at 308.15 K. Isentropic compressibility changes of mixing, have been determined by employing speed of sound data. Topological investigations of VE data reveals that aniline, chloroform and o-toluidine are associated entities and these (i + j) mixtures contain a 1:1 molecular complex. The IR studies lend further support to the nature and extent of interaction for the proposed molecular entity in the mixtures. HE and values have also been calculated by employing Moelwyn-Huggins concept [Polymer 12 (1971) 387] taking topology of the constituents of the mixtures. It has been observed that calculated HE and values compare well with their corresponding experimental values. The observed VE, HE and data have also been analyzed in terms of Flory theory. 相似文献
996.
Experimental study of mixing time of non-Newtonian shear-thinning fluids within the transitional regime (3 × 102 < Re < 3 × 103) of liquid flow is presented. The purpose of this study was to analyze the effect of eccentricity and pumping mode of the
impeller as well as of position of the tracer dosage point into the agitated liquid on mixing time. The measurements were
conducted in an unbaffled agitated vessel with inner diameter D = 0.7 m equipped with an up-or down-pumping propeller located centrically (e/R = 0) or eccentrically (e/R ≠ 0) in the vessel. Experiments were carried out by means of computer-aided unsteady-state thermal method for three positions
of the tracer dosage point. The experimental data show that eccentric position of the propeller in an unbaffled vessel causes
a decrease of the mixing time compared to that obtained in a vessel with a centrically located propeller. Mixing time depends
also on the pumping mode of the propeller as well as on the position of the tracer dosage point.
Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May
2007. 相似文献
997.
Composite cation exchange membranes are prepared from cross-linked styrene-divinylbenzene copolymers for the electrolysis of sodium chloride to produce sodium hydroxide and chlorine by selective removal of sodium ions. It is prepared from a syrup of the polymer using dual initiating system and is modified with chloroacetic acid to introduce acid functional groups (COO−) on its surface. The effect of the modification is confirmed by FTIR, SEM, contact angle, water content, and ion exchange capacity measurements. The performance of the membrane has been evaluated in terms of current efficiency and power consumption and the effect of current density, salt concentration and flow rate on efficiency has been studied. Our membrane has an ion exchange capacity of 0.833 meq./g which is close to that of the commercially available Nafion-117 membrane having an ion exchange capacity 0.9 meq./g. The Nafion-117 used for electrodialysis of sodium sulfate has a current efficiency of around 90% and specific energy consumption of 0.1 kW/mol at 2N concentration of the salt at 1000 A/m2. Our membrane used for electrodialysis of sodium chloride has a current efficiency of 93% and a power consumption of around 0.3122 kW/mol at the same concentration of salt and at a current density of 254 A/m2. The two-dimensional space-charge model in cylindrical coordinates has been solved semi-analytically to obtain the effective wall potential and pore size of the membrane which are difficult to measure directly. The experimentally obtained solute flux and current density have been fitted to the model and optimum values of effective wall potential and pore diameter have been determined to be 98.5 mV and 0.8 nm, respectively. 相似文献
998.
In this paper, a new solvent-free route for preparing proton-conductive membranes is proposed. Flexible and fiber-supported polymer electrolyte membranes, as potential proton exchange membranes, were readily obtained by in situ polymerization of a homogenous solution that consisted of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO, polymer)–monomer mixtures of styrene (ST) and divinylbenzene (DVB), which was pre-cast onto SEFAR PETEX fibers. Factors such as the components of the casting solution and the sulfonation time, were fully investigated. The membrane structure and components were confirmed by FTIR-ATR spectra and SEM-EDXA images, and the thermal stability was examined via TGA and DrTGA. The membrane exhibited a proton conductivity of about 0.07 S/cm at 100% humidity and at room temperature, which is close to that of Nafion 117 at identical conditions (around 0.08 S/cm), whereas its thickness (about 120 μm) was less than that of Nafion 117. The tensile strength and the elongation at the break of the membrane were 31.2 MPa and 71%, respectively, which are several times higher than those of Nafion (about 6.16 MPa tensile strength and 36% elongation ratio). The dimensional change ratio of the membrane between the wet and dry states was below 3%, which is much lower than that of Nafion 117. The membrane showed a high thermal stability up to 400 °C. The method can be applied to other compatible systems of (aromatic) polymers and (aromatic) monomers. 相似文献
999.
Ralph Puchta Rudi van Eldik 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):383-392
Abstract Structures and complex-formation energies, calculated with DFT (B3LYP/LANL2DZp) for the cryptands [2.2.phen] and [2.phen.phen]
with endohedrally complexed alkali and alkaline earth metal ions, were utilized to predict their ion selectivity. Both cryptands
[2.2.phen] and [2.phen.phen] have a cavity size smaller than [2.2.2], [phen.phen.phen] and [bpy.bpy.bpy], and prefer to bind
K+ and Sr2+, whereas [2.2.phen] that is larger than [2.phen.phen], has a preference for Ba2+, and [2.phen.phen] favours Na+ and Ca2+. The cryptand flexibility is mainly attributed to the presence of CH2–NSP3···NSP3–CH2 groups.
Graphical abstract
Host–Guest Complexes of mixed Glycol-Phenanthroline Cryptands—Prediction of Ion Selectivity by Quantum Chemical Calculations
III
Ralph Puchta* and Rudi van Eldik
Keywords
Cation selectivity
Host–guest
DFT
DFT-studies allow a sensitive analysis of selectivity and cage size. Calculations predict a favourable binding of K+, Sr2+ and Ba2+ by [2.2.phen], and binding of K+, Na+, Ca2+ and Sr2+ by [2.phen.phen]. The cryptands fold around the ions by twisting their torsion angles in order to reach the best coordination
mode for each cation.
For “Prediction of ion selectivity by quantum chemical calculations III” see, R. Puchta, R. van Eldik. Aust. J. Chem. 60, 889–897 (2007). 相似文献
1000.
A. Książczak M. Ostrowski W. Tomaszewski 《Journal of Thermal Analysis and Calorimetry》2008,94(1):275-279
The melting and mixing enthalpy of the binary system nitrocellulose and N-nitrodiethanolamine dinitrate (DINA) was determined
by DSC. The mixing enthalpy H
maxM = 1.95 kJ mol−1 had maximum at mass fraction x
wDINA=0.46. The influence of samples storing on glass and endothermic transitions were studied. The temperature range of glass
transition broadened with x
wDINA what proved the increase of samples heterogeneity. For x
wDINA≤0.750 no influence of samples storing on the phase changes was observed. The heat capacity change decreased and temperature
range of glass transition increased for x
wDINA≤0.500 what indicated the reduction of glass phase fraction in studied samples. 相似文献