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排序方式: 共有233条查询结果,搜索用时 15 毫秒
71.
72.
Ocak Y Akbulut S Keşlioğlu K Maraşli N 《Journal of colloid and interface science》2008,320(2):555-562
The grain boundary groove shapes for equilibrated solid neopentylglycol (2,2-dimethyl-1,3-propanediol) (NPG) with its melt were directly observed by using a horizontal temperature gradient stage. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient (Gamma), solid-liquid interfacial energy (sigma(SL)), and grain boundary energy (sigma(gb)) of NPG have been determined to be (7.4+/-0.7)x10(-8) Km, (7.9+/-1.2)x10(-3) Jm(-2), and (15.4+/-2.5)x10(-3) Jm(-2), respectively. The ratio of thermal conductivity of equilibrated liquid phase to solid phase for the NPG has also been measured to be 1.07 at the melting temperature. 相似文献
73.
Hacer Azak Firat Baris Barlas Huseyin Bekir Yildiz Kadri Gulec Bilal Demir Dilek Odaci Demirkol Suna Timur 《Macromolecular bioscience》2016,16(4):545-552
Here, postfunctionalization and bioapplication of a π‐conjugated polymer named 4‐[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl]aniline (DTP‐aryl‐NH2) are reported, which is successfully synthesized via electropolymerization onto the glassy carbon electrode. Folic acid (FA) is used to modify the amino functional polymer via N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride/N‐hydroxysuccinimide chemistry for the further steps. The selective adhesion of folate receptor positive cells on the surface is followed by the electrochemical methods. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize stepwise modification of the electroactive surface. After optimization studies such as scan rate during the polymer deposition, FA amount for the efficient surface targeting, incubation time with the cells etc., analytical characterization is carried out. The surface morphologies at each step are imaged by using fluorescence microscopy.
74.
Michael D. SangidHans J. Maier Huseyin Sehitoglu 《International Journal of Plasticity》2011,27(5):801-821
In this paper, we construct a model for prediction of fatigue crack initiation based on the material’s microstructure. In order to do so, the energy of a persistent slip band (PSB) is monitored and an energy balance approach is taken, in which cracks initiate and the material fails due to stress concentration from a PSB (with respect to dislocation motion). These PSBs are able to traverse low-angle grain boundaries (GB), thus belonging to clusters of grains. As a consequence of the ongoing cyclic slip process, the PSBs evolve and interact with high-angle GBs, the result of which leads to dislocation pile-ups, static extrusions in the form of ledges/steps at the GB, stress concentration, and ultimately crack initiation. Hence, this fatigue model is driven by the microstructure, i.e. grain orientations, widely distributed grain sizes, precipitates, PSB-GB interactions, as well as the affect of neighboring grains. The results predict that cracks initiate near twin boundaries from PSBs spanning a single large grain with a favorable orientation or multiple grains connected by low-angle GBs. Excellent agreement is shown between model predictions and experimental data. 相似文献
75.
Huseyin Onur Mete Yanfang Shen Zelda B. Zabinsky Seksan Kiatsupaibul Robert L. Smith 《Journal of Global Optimization》2011,50(4):597-627
We develop new Markov chain Monte Carlo samplers for neighborhood generation in global optimization algorithms based on Hit-and-Run.
The success of Hit-and-Run as a sampler on continuous domains motivated Discrete Hit-and-Run with random biwalk for discrete
domains. However, the potential for efficiencies in the implementation, which requires a randomization at each move to create
the biwalk, lead us to a different approach that uses fixed patterns in generating the biwalks. We define Sphere and Box Biwalks that are pattern-based and easily implemented for discrete and
mixed continuous/discrete domains. The pattern-based Hit-and-Run Markov chains preserve the convergence properties of Hit-and-Run
to a target distribution. They also converge to continuous Hit-and-Run as the mesh of the discretized variables becomes finer,
approaching a continuum. Moreover, we provide bounds on the finite time performance for the discrete cases of Sphere and Box
Biwalks. We embed our samplers in an Improving Hit-and-Run global optimization algorithm and test their performance on a number
of global optimization test problems. 相似文献
76.
Sibel Kasap Huseyin Tel Sabriye Piskin 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):489-495
The objective of this study is to evaluate the use of titanium dioxide nanoparticles which were prepared by novel sonochemical
method as an ion exchange material for the removal of Sr from aqueous solution. The pH effect on the Sr2+ sorption was investigated. The data obtained have been correlated with Freundlich, Temkin and Dubinin–Radushkevich (D–R)
isotherm models. Thermodynamic parameters fort he sorption system have been determined at four temperatures. Simple kinetic
models have been applied to the rate and isotherm sorption data and the relevant kinetic parameters were determined from the
graphical presentation of these models at 298°K. Results explained that the pseudo second-order sorption mechanism is predominant
and the overall rate constant of sorption process appears to be controlled by chemical sorption process. The value of sorption
energy E = 13 kJ/mol at 298°K and the value of Gibbs free energy ∆G° = 3,222 kJ/mol at 298°K prove that the sorption of strontium on titanium dioxide nanoparticles is an endothermic and non-spontaneous
process. 相似文献
77.
Huseyin Halilov 《Applicable analysis》2013,92(1-2):61-71
In this paper the multidimensional mixed problem for the quasilinear pseudoparabolic equation ut-Lxu-εLxut=f(t,x,u) is considered. Lx is a differential operator, which composes (with boundary operator) a self adjoint operator. An existence, uniqueness and also continuous dependense on the small parameter ε>0 of generalized solution is proved. The estimation of the difference of exact and approximate solutions is obtained 相似文献
78.
We report a narrow-linewidth, tunable, gain-switched Cr:ZnSe laser operating between 2255 and 2455 nm. The spectral width of the laser was reduced from 125 nm to 0.3 nm by using injection seeding. Seeding was achieved with a second tunable CW Cr:ZnSe laser. The output wavelength was varied by tuning the wavelength of the seed laser. The seeded oscillator produced as high as 157 μJ pulses with 598 μJ incident pump pulse energy at a repetition rate of 1 kHz. The slope efficiency was determined to be 26%. 相似文献
79.
Gyaneshwar P. Srivastava Huseyin M. T??t??nc?? 《Central European Journal of Physics》2009,7(2):209-219
We present a mini review of progress made towards theoretical modelling of surface phonons. We outline the essential ingredients
of two theoretical methods, viz. an adiabatic bond charge method for semiconductor surfaces and the ab-initio density-functional perturbation method for solid surfaces in general. From the results of theoretical calculations we establish
trends and criteria for the existence of localized phonon modes on group-IV(001) and III-V(110) semiconductor surfaces. We
further obtain signatures of characteristic vibrational modes which develop during dissociative molecular adsorption on Si(001)
surfaces. The results are compared with available experimental measurements. Some remarks are forwarded regarding manipulation
of surface phonon modes for scientific advances and technological applications.
相似文献
80.
The variations of thermal conductivities of solid phases versus temperature for neopentylglycol (NPG), 2-amino-2-methyl-1,3-propanediol (AMPD) and AMPD-42.2 mol% NPG alloy were measured with a radial heat flow apparatus. From the graphs of the solid phases thermal conductivity variations versus temperature, the thermal conductivities of the solid phases at their melting temperature and temperature coefficients for same materials were also found to be 0.22±0.01, 0.45±0.02 and 0.32±0.02 W/Km and 0.0047, 0.0031 and 0.0043 K−1, respectively. The thermal conductivity ratios of liquid phase to solid phase for the same materials at their melting temperature are found to be 1.07, 1.12 and 0.74 with a Bridgman type directional solidification apparatus, respectively. Thus, the thermal conductivities of liquid phases for pure NPG, pure AMPD and AMPD-42.2 mol% NPG alloy at their melting temperature were evaluated to be 0.24, 0.50 and 0.23 W/Km, respectively, by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase. 相似文献