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21.
Pratap V Moumen N Subramanian RS 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):5185-5193
22.
Optimal construction of quantum operations is a fundamental problem in the realization of quantum computation. We here introduce a newly discovered quantum gate, B, that can implement any arbitrary two-qubit quantum operation with minimal number of both two- and single-qubit gates. We show this by giving an analytic circuit that implements a generic nonlocal two-qubit operation from just two applications of the B gate. Realization of the B gate is illustrated with an example of charge-coupled superconducting qubits for which the B gate is seen to be generated in shorter time than the CNOT gate. 相似文献
23.
Maiti K Singh RS Medicherla VR Rayaprol S Sampathkumaran EV 《Physical review letters》2005,95(1):016404
We investigate the origin of charge density wave (CDW) formation in insulators by studying BaIrO3 using high-resolution (1.4 meV) photoemission spectroscopy. The spectra reveal the existence of localized density of states at the Fermi level, E(F), in the vicinity of room temperature. These localized states are found to vanish as the temperature is lowered, thereby, opening a soft gap at E(F), as a consequence of CDW transition. In addition, the energy dependence of the spectral density of states reveals the importance of magnetic interactions, rather than well-known Coulomb repulsion effect, in determining the electronic structure thereby implying a close relationship between ferromagnetism and CDW observed in this compound. Also, Ba core level spectra surprisingly exhibit an unusual behavior prior to CDW transition. 相似文献
24.
We consider the Lie-Backlund symmetries and conservation laws of a perturbed KdV equation and NLS equation. The arbitrary coefficients of the perturbing terms can be related to the condition of existence of nontrivial LB symmetry generator. When the perturbed KdV equation is subjected to Painlevé analysisa la Weiss, it is found that the resonance position changes compared to the unperturbed one. We prove the compatibility of the overdetermined set of equations obtained at the different stages of recursion relations, at least for one branch. All other branches are also indicated and difficulties associated them are discussed considering the perturbation parameter to be small. We determine the Lax pair for the aforesaid branch through the use of Schwarzian derivative. For the perturbed NLS equation we determine the conservation laws following the approach of Chen and Liu. From the recurrence of these conservation laws a Lax pair is constructed. But the Painlevé analysis does not produce a positive answer for the perturbed NLS equation. So here we have two contrasting examples of perturbed nonlinear equations: one passes the Painlevé test and its Lax pair can be found from the analysis itself, but the other equation does not meet the criterion of the Painlevé test, though its Lax pair is found in another way. 相似文献
25.
26.
We analyze the eigenvalues of the adjacency matrices of a wide variety of random trees. Using general, broadly applicable arguments based on the interlacing inequalities for the eigenvalues of a principal submatrix of a Hermitian matrix and a suitable notion of local weak convergence for an ensemble of random trees that we call probability fringe convergence, we show that the empirical spectral distributions for many random tree models converge to a deterministic (model-dependent) limit as the number of vertices goes to infinity. Moreover, the masses assigned by the empirical spectral distributions to individual points also converge in distribution to constants. We conclude for ensembles such as the linear preferential attachment models, random recursive trees, and the uniform random trees that the limiting spectral distribution has a set of atoms that is dense in the real line. We obtain lower bounds on the mass assigned to zero by the empirical spectral measures via the connection between the number of zero eigenvalues of the adjacency matrix of a tree and the cardinality of a maximal matching on the tree. In particular, we employ a simplified version of an algorithm due to Karp and Sipser to construct maximal matchings and understand their properties. Moreover, we show that the total weight of a weighted matching is asymptotically equivalent to a constant multiple of the number of vertices when the edge weights are independent, identically distributed, nonnegative random variables with finite expected value, thereby significantly extending a result obtained by Aldous and Steele in the special case of uniform random trees. We greatly generalize a celebrated result obtained by Schwenk for the uniform random trees by showing that if any ensemble converges in the probability fringe sense and a very mild further condition holds, then, with probability converging to one, the spectrum of a realization is shared by at least one other (nonisomorphic) tree. For the linear preferential attachment model with parameter a>?1, we show that for any fixed k, the k largest eigenvalues jointly converge in distribution to a nontrivial limit when rescaled by $n^{1/2\gamma_{a}}$ , where ?? a =a+2 is the Malthusian rate of growth parameter for an associated continuous-time branching process. 相似文献
27.
Shyamolina Ghosh Deb Shankar Ray 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(3):1-7
Using first-principles calculation, we have studied the properties of a series of M x Co1?x /Co(0001) (M = Pd, Pt) bimetallic surface alloys with atom M ratios from 0.25 to 1.0, then the effect of alloyed M metal on the properties of S adsorbed on these surfaces are discussed. Our calculations show that the alloying of metal Pd, Pt on Co(0001) weakens the S-M (M = Pd, Pt, Co) bond strength compared to monometallic surfaces and the site preference of sulfur atom is dependent on the alloyed metal M and its surface concentration. Moreover, bimetallic surface electronic structure modifications with and without sulfur are analyzed in comparison with clean Co(0001), and the correlation between the sulfur adsorption energy and the bimetallic surface d-band center is presented. 相似文献
28.
为了能在双模态超燃冲压发动机流道方案初步论证中提供一种较快速的发动机性能计算方法,在二维N-S方程基础上,引入一维完全燃烧计算方法,提出了预估超燃冲压发动机性能的准二维计算方法。该方法能够计入激波、边界层分离等对发动机性能的影响,可在较短时间计算出整机推力、比冲性能和沿程热力学参数。通过对自由射流发动机计算,验证了此方法。并在此基础上,初步分析了燃料喷注位置和流道构型对发动机性能的影响。 相似文献
29.
Modern high-tech products experience rapid obsolescence. Capacity investments must be recouped during the brief product lifecycle, during which prices fall continuously. We employ a multiplicative demand model that incorporates price declines due to both market heterogeneity and product obsolescence, and study a monopolistic firm’s capacity decision. We investigate profit concavity, and characterize the structure of the optimal capacity solution. Moreover, for products with negligible variable costs, we identify two distinct strategies for capacity choice demarcated by an obsolescence rate threshold that relates both to market factors and capacity costs. Finally, we empirically test the demand model by analyzing shipping and pricing data from the PC microprocessor market. 相似文献
30.
s‐Triazine‐Based Functional Discotic Liquid Crystals: Synthesis,Mesomorphism and Photoluminescence 下载免费PDF全文
B. N. Veerabhadraswamy Hashambi K. Dambal D. S. Shankar Rao C. V. Yelamaggad 《Chemphyschem》2016,17(14):2225-2237
A new series of C3‐symmetric, π‐conjugated molecules was designed, synthesized and characterized. The materials were derived from electron‐accepting s‐triazine, appended covalently to electron‐donating styrylbenzene arms, and were readily prepared in excellent yield with high purity by means of three‐fold condensation of triphosphonate with n‐alkoxybenzaldehydes under Horner–Wadsworth–Emmons reaction conditions. Examination of the phase transitional properties by several complementary techniques evidenced self‐assembly into a hexagonal columnar phase, occurring over wide and reasonable thermal ranges. The photophysical properties were studied both in solution and in the fluid/frozen columnar states by UV/Vis absorption and photoluminescence spectroscopy. The emission spectra obtained as a function of the temperature rule out the breaking‐up of larger columns and a non‐radiative, thermally activated process. A study carried out on thin films of the glassy columnar state, which accounts for conserved fluorescence, defect‐free orientation, and freezing ionic species, with the help of atomic force microscopy (AFM) images, suggested a homogeneous granular morphology comprising fibrillar structures. Dissimilarities in the surface morphology and birefringence of thin films of the solid and frozen columnar states were clearly shown by Raman spectroscopy. An electrochemical investigation revealed a LUMO energy of ?4.0 eV. Thus, the discotic motifs presented herein meet certain criteria of organic materials, which are essential for developing electronic devices. 相似文献