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971.
Regine Pei Tze Oh Susan M. Sanchez Thomas W. Lucas Hong Wan Mark E. Nissen 《Computational & Mathematical Organization Theory》2009,15(3):237-257
Simulation experiments are typically faster, cheaper and more flexible than physical experiments. They are especially useful
for pilot studies of complicated systems where little prior knowledge of the system behavior exists. One key characteristic
of simulation experiments is the large number of factors and interactions between factors that impact decision makers. Traditional
simulation approaches offer little help in analyzing large numbers of factors and interactions, which makes interpretation
and application of results very difficult and often incorrect. In this paper we implement and demonstrate efficient design
of experiments techniques to analyze large, complex simulation models. Looking specifically within the domain of organizational
performance, we illustrate how our approach can be used to analyze even immense results spaces, driven by myriad factors with
sometimes unknown interactions, and pursue optimal settings for different performance measures. This allows analysts to rapidly
identify the most important, results-influencing factors within simulation models, employ an experimental design to fully
explore the simulation space efficiently, and enhance system design through simulation. This dramatically increases the breadth
and depth of insights available through analysis of simulation data, reduces the time required to analyze simulation-driven
studies, and extends the state of the art in computational and mathematical organization theory. 相似文献
972.
Fragmentation mechanisms of protonated chalcone and its derivatives with different functional groups were investigated by atmospheric pressure chemical ionization with tandem mass spectrometry (MS/MS). The major fragmentation pathways were loss of the phenyl group from the A or B ring, combined with loss of CO. Losses of H(2)O and CO from the precursor ions of [M+H](+) are proposed to occur via rearrangements. Elimination of water from protonated chalcones was observed in all the title compounds to yield a stable ion but it was difficult to obtain skeletal fragmentation of a precursor ion. Loss of CO was found in the MS/MS spectra of all the compounds except the nitro-substituted chalcones. When the [M+H--CO](+) ion was fragmented in the MS/MS experiments, there were distinctive losses of 15 and 28 Da, as the methyl radical and ethylene, respectively. The ion at m/z 130, found only in the nitro-substituted chalcones, was assigned as C(9)H(6)O by Fourier transform ion cyclotron resonance (FTICR)-MS/MS; m/z 130 is a common fragment ion in the electron ionization (EI) spectra of chalcones. In order to more easily distinguish the constitutional isomers of these chalcones, breakdown curves were produced and these provided strong support in this study. 相似文献
973.
Sunintaboon P Ho KM Li P Cheng SZ Harris FW 《Journal of the American Chemical Society》2006,128(7):2168-2169
A new, simplified route to amphiphilic core-shell nanotubes, microfibers, and microrods has been developed that does not involve the traditional utilization of well-defined block copolymers. Thus, amphiphilic graft copolymers (PEI-g-PMMA) are prepared by an aqueous free radical polymerization that self-assemble in situ to form uniform core-shell nanoparticles. The hydrophobic homopolymer (PMMA) that is also formed is incorporated in the cores. Slight cross-linking of the shells followed by extraction of the homopolymer results in hollow nanoparticles that coalesce to form nanotubes. When the shells are not cross-linked, the hollow particles coalesce to form microrods and microfibers. The sizes and shapes of the micromaterials can be controlled by varying the experimental conditions. 相似文献
974.
Korth BD Keng P Shim I Bowles SE Tang C Kowalewski T Nebesny KW Pyun J 《Journal of the American Chemical Society》2006,128(20):6562-6563
A novel synthetic route to polymer-coated ferromagnetic colloids of metallic cobalt has been developed. Well-defined end-functional polystyrenes were synthesized using controlled radical polymerization and used as surfactants in the thermolysis of dicobaltoctacarbonyl to afford uniform ferromagnetic nanoparticles. The presence of the polymer shell enabled prolonged colloidal stability of dispersions in a wide range of organic solvents and formed glassy encapsulating coatings around ferromagnetic cores in the solid state. These polymer-coated colloids assembled into robust, micron-sized nanoparticle chains when cast onto supporting surfaces due to dipolar associations of magnetic cores. Hierarchical assemblies were also prepared by blending polystyrene-coated cobalt colloids with larger silica beads. 相似文献
975.
Two large pi-conjugated dendrimers (G0 and G1) employing the stilbenoid moiety as the bridge unit have been developed through the Suzuki and the Horner-Wadsworth-Emmons reactions. The molecular weight of G1 is 10 973 Da. Both G0 and G1 have good fluorescence quantum yields and exhibit similar absorption and emission behaviors in solutions and in thin films. They emit strong blue fluorescence in films under the irradiation of UV light. 相似文献
976.
A theoretical model for the propagation of shock wave from an axisymmetric reflector was developed by modifying the initial conditions for the conventional solution of a nonlinear parabolic wave equation (i.e., the Khokhlov-Zabolotskaya-Kuznestsov equation). The ellipsoidal reflector of an HM-3 lithotripter is modeled equivalently as a self-focusing spherically distributed pressure source. The pressure wave form generated by the spark discharge of the HM-3 electrode was measured by a fiber optic probe hydrophone and used as source conditions in the numerical calculation. The simulated pressure wave forms, accounting for the effects of diffraction, nonlinearity, and thermoviscous absorption in wave propagation and focusing, were compared with the measured results and a reasonably good agreement was found. Furthermore, the primary characteristics in the pressure wave forms produced by different reflector geometries, such as that produced by a reflector insert, can also be predicted by this model. It is interesting to note that when the interpulse delay time calculated by linear geometric model is less than about 1.5 micros, two pulses from the reflector insert and the uncovered bottom of the original HM-3 reflector will merge together. Coupling the simulated pressure wave form with the Gilmore model was carried out to evaluate the effect of reflector geometry on resultant bubble dynamics in a lithotripter field. Altogether, the equivalent reflector model was found to provide a useful tool for the prediction of pressure wave form generated in a lithotripter field. This model may be used to guide the design optimization of reflector geometries for improving the performance and safety of clinical lithotripters. 相似文献
977.
For a contraction A on a Hilbert space H, we define the index j(A) (resp., k(A)) as the smallest nonnegative integer j (resp., k) such that ker(I−Aj∗Aj) (resp., ker(I−Ak*Ak)∩ker(I−AkAk∗)) equals the subspace of H on which the unitary part of A acts. We show that if , then j(A)?n (resp., k(A)?⌈n/2⌉), and the equality holds if and only if A is of class Sn (resp., one of the three conditions is true: (1) A is of class Sn, (2) n is even and A is completely nonunitary with ‖An−2‖=1 and ‖An−1‖<1, and (3) n is even and A=U⊕A′, where U is unitary on a one-dimensional space and A′ is of class Sn−1). 相似文献
978.
Xuehui Ji Yongzhen Pei Changguo Li 《Nonlinear Analysis: Real World Applications》2010,11(3):2078-2090
In this paper, two SIR epidemic models with different patterns of recruitment and difference in immunity are investigated. When the recruitment rate is less than some threshold value, the disease will be eradicated. Furthermore, for the continuous recruitment model, according to the Poincare–Bendixson theorem, the global asymptotical stability of a unique positive equilibrium is obtained. For the pulse recruitment model, we investigated the existence of nontrivial periodic solutions via a supercritical (subcritical) bifurcation. From a biological point of view, our results indicate that (1) the disease can be eradicated if the recruitment rate is controlled under some threshold; (2) the number of the infected increases as the difference in immunity increases; (3) fewer individuals are infected as the pulse recruitment is taken, displaying its effect on the control of the disease. 相似文献
979.
This paper is concerned with the following fourth-order m-point nonhomogeneous boundary value problem $$\begin{array}{l}u^{(4)}(t)=f(t,u(t),u^{\prime \prime }(t)),\quad 0<t<1,\\[3pt]u(0)=u(1)=u^{\prime \prime }(0)=0,\\[3pt]u^{\prime \prime }(1)-\displaystyle\sum_{i=1}^{m-2}a_{i}u^{\prime\prime }(\xi _{i})=-\lambda ,\end{array}$$ where a i ≥0 (i=1,2,…,m?2), 0<ξ1<ξ2<???<ξ m?2<1 and ∑ i=1 m?2 a i ξ i <1, and λ>0 is a parameter. The existence and nonexistence of positive solution are discussed for suitable λ>0 when f is superlinear or sublinear. The main tool used is the well-known Guo-Krasnoselskii fixed point theorem. 相似文献
980.
Algebraic immunity has been considered as one of cryptographically significant properties for Boolean functions. In this paper, we study ∑d-1 i=0 (ni)-weight Boolean functions with algebraic immunity achiev-ing the minimum of d and n - d + 1, which is highest for the functions. We present a simpler sufficient and necessary condition for these functions to achieve highest algebraic immunity. In addition, we prove that their algebraic degrees are not less than the maximum of d and n - d + 1, and for d = n1 +2 their nonlinearities equalthe minimum of ∑d-1 i=0 (ni) and ∑ d-1 i=0 (ni). Lastly, we identify two classes of such functions, one having algebraic degree of n or n-1. 相似文献