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61.
Sergey Semenov Anna Trybala Ramon G. Rubio Nina Kovalchuk Victor Starov Manuel G. Velarde 《Advances in colloid and interface science》2014
The recent progress in theoretical and experimental studies of simultaneous spreading and evaporation of liquid droplets on solid substrates is discussed for pure liquids including nanodroplets, nanosuspensions of inorganic particles (nanofluids) and surfactant solutions. Evaporation of both complete wetting and partial wetting liquids into a nonsaturated vapour atmosphere are considered. However, the main attention is paid to the case of partial wetting when the hysteresis of static contact angle takes place. In the case of complete wetting the spreading/evaporation process proceeds in two stages. A theory was suggested for this case and a good agreement with available experimental data was achieved. In the case of partial wetting the spreading/evaporation of a sessile droplet of pure liquid goes through four subsequent stages: (i) the initial stage, spreading, is relatively short (1–2 min) and therefore evaporation can be neglected during this stage; during the initial stage the contact angle reaches the value of advancing contact angle and the radius of the droplet base reaches its maximum value, (ii) the first stage of evaporation is characterised by the constant value of the radius of the droplet base; the value of the contact angle during the first stage decreases from static advancing to static receding contact angle; (iii) during the second stage of evaporation the contact angle remains constant and equal to its receding value, while the radius of the droplet base decreases; and (iv) at the third stage of evaporation both the contact angle and the radius of the droplet base decrease until the drop completely disappears. It has been shown theoretically and confirmed experimentally that during the first and second stages of evaporation the volume of droplet to power 2/3 decreases linearly with time. The universal dependence of the contact angle during the first stage and of the radius of the droplet base during the second stage on the reduced time has been derived theoretically and confirmed experimentally. The theory developed for pure liquids is applicable also to nanofluids, where a good agreement with the available experimental data has been found. However, in the case of evaporation of surfactant solutions the process deviates from the theoretical predictions for pure liquids at concentration below critical wetting concentration and is in agreement with the theoretical predictions at concentrations above it. 相似文献
62.
63.
Design,Degradation Mechanism and Long‐Term Cytotoxicity of Poly(l‐lactide) and Poly(Lactide‐co‐ϵ‐Caprolactone) Terpolymer Film and Air‐Spun Nanofiber Scaffold 下载免费PDF全文
64.
Crovetto L Rios R Alvarez-Pez JM Paredes JM Lozano-Velez P del Valle C Talavera EM 《The journal of physical chemistry. B》2008,112(33):10082-10085
The 2,5-dioxopyrrolidin-1-yl-4-(3-hydroxy-6-oxo-6H-xanthen-9-yl)-3-methylbenzoate has been synthesized as an amine-reactive derivative able to yield stable covalently labeled biopolymers. The new derivative has been used to label polyribocytidilic acid (5'), poly(C), amine residues. TG-II-poly(C) exhibits monoexponential decay at the physiological pH range. In addition, both steady-state fluorescence intensity and fluorescence decay are also sensitive to solution pH. The large decrease in steady-state fluorescence upon hybridization allows it to be used as a nucleic acid probe in a homogeneous assay format. In summary, we report an efficient synthesis to obtain labeled RNA from commercially available materials in excellent yields. 相似文献
65.
The batch emulsion copolymerization of vinyl acetate with different vinyl silane functional monomers (vinyl trimethoxysilane [VTMS], vinyl triethoxysilane [VTES], and vinyl silanetriol [VSTO]) is studied. The nature of the silane strongly affects the development of the microstructure and crosslinking ability of the latexes. A combination of techniques (Soxhlet extraction, centrifugation, assymetric‐flow field flow fractionation AF4/MALS/RI) shows that the factor controlling the molar mass and crosslinking density is the degree of hydrolysis of the alkoxysilane, producing higher molar masses and degrees of crosslinking when the degree of hydrolysis is high. Thus, the copolymer containing VSTO produced a very crosslinked latex, the one with VTMS produced a latex with a low degree of crosslinking in the wet state that can yield high degrees of crosslinking upon drying, and the latex with VTES do not produce significant amounts of crosslinking neither before nor after drying. 相似文献
66.
A specific, sensitive, precise, and accurate method for the determination of abscisic acid (ABA) in grapevine leaf tissues
is described. The method employs high-performance liquid chromatography and electrospray ionization–mass spectrometry (LC-ESI-MS)
in selected ion monitoring mode (SIM) to analyze ABA using a stable isotope-labeled ABA as an internal standard. Absolute
recoveries ranged from 72% to 79% using methanol/water pH 5.5 (50:50 v/v) as an extraction solvent. The best efficiency was
obtained when the chromatographic separation was carried out by using a porous graphitic carbon (PGC) column. The statistical
evaluation of the method was satisfactory in the work range. A relative standard deviation (RDS) of < 5.5% and < 6.0% was
obtained for intra-batch and inter-batch comparisons, respectively. As for accuracy, the relative error (%Er) was between
−2.7 and 4.3%, and the relative recovery ranged from 95% to 107%. 相似文献
67.
Ramon Rios 《Tetrahedron letters》2006,47(48):8547-8551
A highly enantioselective catalytic asymmetric synthesis of 2H-1-benzothiopyrans is presented. The organocatalytic asymmetric domino reactions between 2-mercaptobenzaldehyde and α,β-unsaturated aldehydes proceed with excellent chemo- and enantioselectivities to give the corresponding pharmaceutically valuable benzothiopyrans in high yields with 91-98% ee. 相似文献
68.
Nikhil M. Kriplani David P. Nackashi Christian J. Amsinck Neil H. Di Spigna Michael B. Steer Paul D. Franzon Ramon L. Rick Gemma C. Solomon Jeffrey R. Reimers 《Chemical physics》2006
Two efficient, physically based models for the real-time simulation of molecular device characteristics of single molecules are developed. These models assume that through-molecule tunnelling creates a steady-state Lorentzian distribution of excess electron density on the molecule and provides for smooth transitions for the electronic degrees of freedom between the tunnelling, molecular-excitation, and charge-hopping transport regimes. They are implemented in the fREEDA™ transient circuit simulator to allow for the full integration of nanoscopic molecular devices in standard packages that simulate entire devices including CMOS circuitry. Methods are presented to estimate the parameters used in the models via either direct experimental measurement or density-functional calculations. The models require 6–8 orders of magnitude less computer time than do full a priori simulations of the properties of molecular components. Consequently, molecular components can be efficiently implemented in circuit simulators. The molecular-component models are tested by comparison with experimental results reported for 1,4-benzenedithiol. 相似文献
69.
Ramon Carbó-Dorca 《Journal of mathematical chemistry》2008,43(3):1076-1101
Partition of the first order density function within LCAO MO theory permits the definition of Mulliken and Minkowski metric
spaces. The metric matrices obtained become useful to connect density atomic partition with quantum similarity measures, Mulliken
populations, EHT, expectation values of Hermitian operators and the comparison of two density distributions. 相似文献
70.
Ramon Carbó-Dorca 《Journal of mathematical chemistry》2008,44(1):228-234
An Aufbau recursive algorithm, leading to the construction of molecular Quantum similarity matrices (QSM) with positive definite
structure is described. As a consequence, Molecular Quantum Similarity measures optimization has to be restricted by a recursive
constraint, related to the Euclidian norm of the QSM column elements in Quantum Object density tag reciprocal space. 相似文献