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71.
Prediction of bulk metallic glass (BMG) forming compositions has always been a challenge due to thermodynamic and kinetic constraints. In the present investigation, a parameter based on the enthalpy of chemical mixing (?Hchem) and the mismatch entropy (?Sσ/kB) has been used to correlate with glass forming ability in some Zr based BMGs. The new thermodynamic parameter, PHS = ?Hchem × ?Sσ/kB, is found to have strong correlation with glass forming ability in the configurational entropy (?Sconfig/R) range of 0.9–1.0. PHS has been calculated for compositions in Zr–Cu–Ag, Zr–Cu–Al, Zr–Cu–Ti and Zr–Cu–Ga ternary systems. It is observed that in all the systems studied, the best BMG composition (highest critical diameter (Zc) of glass formation) is the one that corresponds to the highest negative PHS value. Present approach using PHS could be road map to design new BMG forming compositions. 相似文献
72.
A Th(IV) compound, [Th(TFSI)4(HTFSI)].2H2O [where TFSI = N(SO2CF3)2], has been synthesized and characterized using elemental analysis, thermogravimetric analysis, and vibrational spectroscopy. The analysis suggests that the TFSI anion coordinates to the metal center via the sulfonyl oxygens as well as provides evidence for the coordination of HTFSI. The voltammetric behavior of this compound has been studied in the room-temperature ionic liquid [Me3NnBu][TFSI], and results show that Th(IV) is reduced to Th(0) in this ionic liquid in a single reduction step. Analysis of cyclic voltammograms shows that an insoluble product is being formed at the electrode surface, which is attributed to the formation of ThO2 by reaction with water. The E0 value for the reduction of Th(IV) to Th(0) has been determined to be -2.20 V (vs Fc+/Fc; -1.80 V vs SHE). A comparison of this E0 value with those obtained for Th(IV) reduction in a LiCl-KCl eutectic (400 degrees C), water, and nonaqueous solvents shows that the reduction in [Me3NnBu][TFSI] is easier to accomplish than that in these other solvents. 相似文献
73.
Jain DS Subbaiah G Sanyal M Shrivastav PS Pal U Ghataliya S Kakad A Bhatt J Munjal V Patel H Shah S 《Rapid communications in mass spectrometry : RCM》2006,20(19):2921-2931
A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the determination of isosorbide-5-mononitrate (5-ISMN), used in the treatment of angina pectoris, in human plasma is described. The quantification of 5-ISMN was performed via stable acetate adduct formation with a high relative abundance. The plasma filtrate obtained after solid-phase extraction (SPE), using a polymer based, hydrophilic-lipophilic balanced (HLB) cartridge, was submitted directly to reversed-phase high-performance liquid chromatography separation followed by ESI and detection of the resulting ions using triple-quadrupole mass spectrometry in selected reaction monitoring (SRM) mode. There was no significant matrix effect on the analysis. For validation of the method, the recovery of the free analyte response was compared to that obtained from an optimized extraction method. The analyte stability was examined under conditions mimicking the sample storage, handling, and analytical procedures. The extraction procedure yielded extremely clean extracts with a recovery of 95.51% and 93.98% for iossorbide-5-mononitrate and topiramate (internal standard (IS)), respectively. The calibration curves were linear for the dynamic range of 10.0 to 1000.0 ng/mL with a correlation coefficient r > or = 0.9985. The intra-assay and inter-assay precision for the samples at the lower limit of quantification (LLOQ) were 9.02 and 13.30%, respectively. The intra-assay accuracies at LLOQ, LQC, MQC and HQC levels varied from 98.13 to 118.15, 102.34 to 105.21, 100.69 to 109.68, and 95.76 to 102.92%, respectively, while the inter-assay accuracies ranged from 93.10 to 118.15, 93.03 to 107.04, 86.97 to 109.68 and 86.18 to 105.85%, respectively, at these levels. The method is rugged and fast with a total run time of 2 min. The method was successfully applied for a bioequivalence study in 24 human subject samples after oral administration of 60 mg extended release (ER) formulations. 相似文献
74.
We present the calculations of electrical resistivity, thermo-electric power and thermal conductivity based on the self-consistent approximation. The pseudopotential due to Hasegawa et al. [J. Non-Cryst. Solids 117/118, 300 (1990)] for full electron–ion interaction, which is valid for all electrons and contains the repulsive delta function to achieve the necessary s-pseudisation, was used in the calculation. Temperature dependence of structure factor is achieved through temperature-dependent potential parameter in the pair-potential. The outcome of the present study is discussed in the light of other such results and with predictions of Wiedemann and Franz law up to moderately high temperature. Specially, high-temperature resistivity data necessitates the careful investigation of electron energy dispersion close to the Fermi level and possible metal to non-metal transition while going from dense-fluid to low density-fluid state. In the absence of experimental data at high temperature, these findings may serve as future guideline. 相似文献
75.
Kanthecha Darshana N. Bhatt Bhupesh S. Patel Mohan N. Vaidya Foram U. Pathak Chandramani 《Molecular diversity》2022,26(4):2085-2101
Molecular Diversity - Pyrazine-bipyrazole-based µ-oxo bridged dinuclear Au(III) complexes were synthesized and characterized by various spectrometric (1H-NMR, 13C (APT) NMR, FT-IR, Mass... 相似文献
76.
Mahesh Datt Bhatt Akihisa Baba Takeaki Sakurai Katsuhiro Akimoto 《Journal of Solid State Electrochemistry》2012,16(3):1141-1149
We have performed ultraviolet photoelectron spectroscopy measurements and density functional theory calculations to study
the electronic structure at the interface between organic semiconductor (3-(4-biphenylyl)-4-phenyl-5-(4-tert-butyl phenyl)-1,2,4-triazole
(TAZ)) and metals (Ca, Mg, Ag, and Au). The basic mechanism of interface states at organic–metal interfaces can be understood
by controlling the injection of charge carriers at these interfaces. The position of highest occupied molecular orbital relative
to the Fermi level and the magnitude of the interface dipole are measured for each organic–metal interface. For TAZ on Ca,
Mg, and Ag, interface states are observed near the Fermi level. However, no interface state is observed for TAZ on Au. It
is analyzed qualitatively that the interface state is formed due to interaction of TAZ lowest unoccupied molecular orbital
composed of C2p and metal s levels. It is suggested that the interface state plays an important role in charge transport at
the interface. The mechanism of formation of interface states and electrical properties are discussed. 相似文献
77.
78.
Pramod Bhatt S. M. Yusuf Ranu Bhatt G. Schütz 《Applied Physics A: Materials Science & Processing》2012,109(2):459-469
The nanoparticles of Prussian blue-based molecular magnets, M 3[Cr(CN)6]2?zH2O (where M=Fe, Co, and Ni), prepared by a slow addition (drop by drop) of chemicals using the co-precipitation method, are investigated by means of X-ray diffraction, infra red spectroscopy and dc magnetization measurement techniques. The formation of nanoparticles has been confirmed by scanning electron microscopy, whereas the characteristic peak, observed in the range of 1900–2300 cm?1 in the infrared spectra, corresponds to the CN stretching frequency of $\mbox{Cr}^{\mathrm{+III}}$ –CN– $M^{\mathrm{+II}}$ , and confirms the formation of Prussian blue compounds. The results, derived from the Rietveld refinement of X-ray diffraction patterns, reveal that all samples are nanocrystalline in nature with a face-centered cubic crystal structure of space group Fm3m. The particle size and the lattice constants decrease with an increasing atomic number of the transition metals (M=Fe, Co and Ni). The magnetization data show a magnetically ordered state of all nanoparticle samples with a low coercivity (except for the Fe3[Cr(CN)6]2?zH2O) as well as the remanent magnetization. In addition, by varying M with Fe, Co and Ni, the magnetic ordering temperature increases from ~12 to ~28 K, whereas the maximum magnetization and the coercive field decrease from ~14 to ~4.5 μB/f.u. and ~554 to ~22 Oe, respectively. The observed magnetization behavior has been discussed in terms of the structural changes due to the decreasing particle size as well as the varying nature of the metal ions. 相似文献
79.
Bahadur J Sen D Mazumder S Paul B Bhatt H Singh SG 《Langmuir : the ACS journal of surfaces and colloids》2012,28(3):1914-1923
Micrometric grains of anisotropic morphology have been achieved by evaporation-induced self-assembly of silica nanoparticles. The roles of polymer concentration and its molecular weight in controlling the buckling behavior of drying droplets during assembly have been investigated. Buckled doughnut grains have been observed in the case of only silica colloid. Such buckling of the drying droplet could be arrested by attaching poly(ethylene glycol) on the silica surface. The nature of buckling in the case of only silica as well as modified silica colloids has been explained in terms of theory of homogeneous elastic shell under capillary pressure. However, it has been observed that colloids, modified by polymer with relatively large molecular weight, gives rise to buckyball-type grains at higher concentration and could not be explained by the above theory. It has been demonstrated that the shell formed during drying of colloidal droplet in the presence of polymer becomes inhomogeneous due to the presence of soft polymer rich zones on the shell that act as buckling centers, resulting in buckyball-type grains. 相似文献
80.
MP Bhatt P Sista J Hao N Hundt MC Biewer MC Stefan 《Langmuir : the ACS journal of surfaces and colloids》2012,28(35):12762-12770
The influence of the solvent and annealing temperature on the field-effect mobilities and morphologies of poly(3-hexylthiophene)-b-poly(γ-benzyl-l-glutamate) (P3HT-b-PBLG) rod-rod diblock copolymer has been investigated. Thin film X-ray diffraction studies show peaks originating from both P3HT and PBLG indicating that the crystalline nature of both the blocks is conserved after the formation of the block copolymer. It has been observed that the field-effect mobilities of the diblock copolymer are independent of the annealing temperatures for thin films deposited from both 1,2,4-trichlorobenzene and chloroform solvents. The correlation between the field-effect mobility and morphology indicates that the P3HT block self-assembles at the surface SiO(2) dielectric. 相似文献