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101.
Jackson TR Springall JS Rogalle D Masumoto N Ching Li H D'Hooge F Perera SP Jenkins AT James TD Fossey JS van den Elsen JM 《Electrophoresis》2008,29(20):4185-4191
The incorporation of specialised carbohydrate affinity ligand methacrylamido phenylboronic acid in polyacrylamide gels for fluorophore-assisted carbohydrate electrophoresis greatly improved the effective separation of saccharides that show similar mobilities in standard electrophoresis. Polyacrylamide gel electrophoresis using methacrylamido phenylboronic acid in low loading (typically 0.5-1% dry weight) was unequivocally shown to alter retention of labelled saccharides depending on their boronate affinity. While conventional fluorophore-assisted carbohydrate electrophoresis of 2-aminoacridone labelled glucose oligomers showed an inverted parabolic migration, an undesired trait of small oligosaccharides labelled with this neutral fluorophore, boron affinity saccharide electrophoresis separation of these carbohydrates completely restored their predicted running order, based on their charge/mass ratio, and resulted in improved separation of the analyte saccharides. These results exemplify boron affinity saccharide electrophoresis as an important new technique for analysing carbohydrates and sugar-containing molecules. 相似文献
102.
Lotrich V Flocke N Ponton M Yau AD Perera A Deumens E Bartlett RJ 《The Journal of chemical physics》2008,128(19):194104
ACES III is a newly written program in which the computationally demanding components of the computational chemistry code ACES II [J. F. Stanton et al., Int. J. Quantum Chem. 526, 879 (1992); [ACES II program system, University of Florida, 1994] have been redesigned and implemented in parallel. The high-level algorithms include Hartree-Fock (HF) self-consistent field (SCF), second-order many-body perturbation theory [MBPT(2)] energy, gradient, and Hessian, and coupled cluster singles, doubles, and perturbative triples [CCSD(T)] energy and gradient. For SCF, MBPT(2), and CCSD(T), both restricted HF and unrestricted HF reference wave functions are available. For MBPT(2) gradients and Hessians, a restricted open-shell HF reference is also supported. The methods are programed in a special language designed for the parallelization project. The language is called super instruction assembly language (SIAL). The design uses an extreme form of object-oriented programing. All compute intensive operations, such as tensor contractions and diagonalizations, all communication operations, and all input-output operations are handled by a parallel program written in C and FORTRAN 77. This parallel program, called the super instruction processor (SIP), interprets and executes the SIAL program. By separating the algorithmic complexity (in SIAL) from the complexities of execution on computer hardware (in SIP), a software system is created that allows for very effective optimization and tuning on different hardware architectures with quite manageable effort. 相似文献
103.
Remeš M Roithová J Schröder D Cope ED Perera C Senadheera SN Stensrud K Ma CC Givens RS 《The Journal of organic chemistry》2011,76(7):2180-2186
Electrospray ionization of methanolic solutions of p-hydroxyphenacyl derivatives HO-C(6)H(4)-C(O)-CH(2)-X (X = leaving group) provides abundant signals for the deprotonated species which are assigned to the corresponding phenolate anions (-)O-C(6)H(4)-C(O)-CH(2)-X. Upon collisional activation in the gas phase, these anions inter alia undergo loss of a neutral "C(8)H(6)O(2)" species concomitant with formation of the corresponding anions X(-). The energies required for the loss of the neutral roughly correlate with the gas phase acidities of the conjugate acids (HX). Extensive theoretical studies performed for X = CF(3)COO in order to reveal the energetically most favorable pathway for the formation of neutral "C(8)H(6)O(2)" suggest three different routes of similar energy demands, involving a spirocyclopropanone, epoxide formation, and a diradical, respectively. 相似文献
104.
Piquemal JP Perera L Cisneros GA Ren P Pedersen LG Darden TA 《The Journal of chemical physics》2006,125(5):054511
Molecular dynamics simulations were performed using a modified amoeba force field to determine hydration and dynamical properties of the divalent cations Ca2+ and Mg2+. The extension of amoeba to divalent cations required the introduction of a cation specific parametrization. To accomplish this, the Thole polarization damping model parametrization was modified based on the ab initio polarization energy computed by a constrained space orbital variation energy decomposition scheme. Excellent agreement has been found with condensed phase experimental results using parameters derived from gas phase ab initio calculations. Additionally, we have observed that the coordination of the calcium cation is influenced by the size of the periodic water box, a recurrent issue in first principles molecular dynamics studies. 相似文献
105.
Szalay PG Watson T Perera A Lotrich VF Bartlett RJ 《The journal of physical chemistry. A》2012,116(25):6702-6710
Equation of motion excitation energy coupled-cluster (EOMEE-CC) methods including perturbative triple excitations have been used to set benchmark results for the excitation energy and oscillator strength of the building units of DNA, i.e., cytosine, guanine, adenine and thymine. In all cases the lowest twelve transitions have been considered including valence and Rydberg ones. Triple-ζ basis sets with diffuse functions have been used and the results are compared to CC2, CASPT2, TDDFT, and DFT/MRCI results from the literature. The results clearly show that it is only the EOMEE-CCSD(T) that is capable of providing accuracy of about 0.1 eV. EOMEE-CCSD systematically overshoots the energy of all types of transitions by 0.1-0.3 eV, whereas CC2 is surprisingly accurate for ππ* transitions but fails (often badly) for nπ* and Rydberg transitions. DFT and CASPT2 seem to give reliable results for the lowest transition, but the error increases fast with the excitation level. The differences in the excitation energies often change the energy ordering of the states, which should even influence the conclusions of excited state dynamics obtained with these approximate methods. The results call for further benchmark calculations on larger building blocks of DNA (nucleosides, basis pairs) at the CCSD(T) level. 相似文献
106.
Milinda C. Senarathna Dr. He Li Sachini D. Perera Jose Torres-Correas Shashini D. Diwakara Samuel R. Boardman Noora M. Al-Kharji Dr. Yi Liu Prof. Ronald A. Smaldone 《Angewandte Chemie (International ed. in English)》2023,62(49):e202312617
Covalent organic frameworks (COFs) are known to be a promising class of materials for a wide range of applications, yet their poor solution processability limits their utility in many areas. Here we report a pore engineering method using hydrophilic side chains to improve the processability of hydrazone and β-ketoenamine-linked COFs and the production of flexible, crystalline films. Mechanical measurements of the free-standing COF films of COF-PEO-3 (hydrazone-linked) and TFP-PEO-3 (β-ketoenamine-linked), revealed a Young's modulus of 391.7 MPa and 1034.7 MPa, respectively. The solubility and excellent mechanical properties enabled the use of these COFs in dielectric devices. Specifically, the TFP-PEO-3 film-based dielectric capacitors display simultaneously high dielectric constant and breakdown strength, resulting in a discharged energy density of 11.22 J cm−3. This work offers a general approach for producing solution processable COFs and mechanically flexible COF-based films, which hold great potential for use in energy storage and flexible electronics applications. 相似文献
107.
We have implemented a model of I 2 ? (CO2) n (2 ≤n ≤ 17) clusters and present an analysis of the minimum energy structures obtained from a quenching procedure. A discussion of the importance of various potential contributions to the energetics of the clusters is also presented. Given the current state of understanding of structural control of caging and the time scales of recombination and evaporation, this model has important implications for understanding the picosecond dynamics observed by the Lineberger group and for rigorous studies of evaporation rates. 相似文献
108.
Gonzalo Perera Mario Wschebor 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2002,38(6):1009
We give a hypothesis testing method to fit the diffusion coefficient σ of a d-dimensional stochastic differential equation on the basis of the observation of certain functionals of regularizations of the solution. 相似文献
109.
F. J. Himpsel H. Akatsu J. A. Carlisle D. G. J. Sutherland I. Jimenez L. J. Terminello J. J. Jia T. A. Callcott M. G. Samant J. Sthr D. L. Ederer R. C. C. Perera W. Tong D. K. Shunh 《Progress in Surface Science》1995,50(1-4):37-51
A third generation of synchrotron radiation facilities is coming on line worldwide, whose brilliance exceeds previous ultraviolet and x-ray light sources by four orders of magnitude. The capabilities at second and third generation light sources are discussed, using examples in surface and interface chemistry and magnetic nanostructures. The authors' experience at the IBM-Tennessee-Tulane-LLNL-LBL undulator beam line will serve as a hands-on guide for work at one of the new facilities. 相似文献
110.