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91.
92.
Ludwig Maier Guenter Rist Peter J. Lea 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):349-352
Abstract The synthesis and properties of phosphinothricin derivatives which have different alkyl groups attached to phosphorus or bear a substituent on the nitrogen are described and their biological activities discussed. 相似文献
93.
A diagonal entropy, which depends only on the diagonal elements of the system's density matrix in the energy representation, has been recently introduced as the proper definition of thermodynamic entropy in out-of-equilibrium quantum systems. We study this quantity after an interaction quench in lattice hard-core bosons and spinless fermions, and after a local chemical potential quench in a system of hard-core bosons in a superlattice potential. The former systems have a chaotic regime, where the diagonal entropy becomes equivalent to the equilibrium microcanonical entropy, coinciding with the onset of thermalization. The latter system is integrable. We show that its diagonal entropy is additive and different from the entropy of a generalized Gibbs ensemble, which has been introduced to account for the effects of conserved quantities at integrability. 相似文献
94.
The Superacid HBr/AlBr3: Protonation of Benzene and Ordered Crystal Structure of [C6H7]+[Al2Br7]− 下载免费PDF全文
Dipl.‐Chem. Franziska Scholz Dr. Daniel Himmel B. Sc. Lea Eisele B. Sc. Wiebke Unkrig Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2014,53(6):1689-1692
Crystalline and properly ordered protonated benzene as the [C6H7]+[Al2Br7]??(C6H6) salt 1 are obtained by the combination of solid AlBr3, benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X‐Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently. 相似文献
95.
Dr. Nason Ma'ani Hessari Dr. Lea Spindler Tinkara Troha Dr. Wan‐Chi Lam Prof. Irena Drevenšek‐Olenik Dr. Mateus Webba da Silva 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3626-3630
The ability to produce, reproducibly and systematically, well‐defined quadruplex DNA nanowires through controlled rational design is poorly understood despite potential utility in structural nanotechnology. The programmed hierarchical self‐assembly of a long four‐stranded DNA nanowire through cohesive self‐assembly of GpC and CpG “sticky” ends is reported. The encoding of bases within the quadruplex stem allows for an uninterrupted π‐stacking system with rectilinear propagation for hundreds of nanometers in length. The wire is mechanically stable and features superior nuclease resistance to double‐stranded DNA. The study indicates the feasibility for programmed assembly of uninterrupted quadruplex DNA nanowires. This is fundamental to the systematic investigation of well‐defined DNA nanostructures for uses in optoelectronic and electronic devices as well as other structural nanotechnology applications. 相似文献
96.
Ashby D.E.T.F. Eastwood J.W. Allen J. Hawkins K.C. Lea L.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(6):959-969
The MILO is a crossed-field HPM, high power microwave source which uses its self-generated magnetic field to cut off electron flow to the anode. A detailed comparison of experimental results and a computer simulation has been made for a number of simple axisymmetric MILO structures designed to operate at 1 GHz. The structures were built from demountable components which enabled the number of cavities and their dimensions to be rapidly altered. Measurements were made of the fluctuating magnetic fields at the end of each cavity. The amplitude and depth of RF modulation of the magnetic fields, although repeatable, changed drastically from one configuration to the next; these parameters were compared with predictions from VIPER, a 2-D electromagnetic PIC code. Good quantitative agreement was obtained between experiments and the simulation in most situations, although, late in the current pulse, after about 100 ns, the level of RF began to decay; a phenomenon which became more pronounced as the applied voltage was increased. The decay was attributed to plasma formation on the cavity vanes and subsequent electron emission; this explanation was verified by computer modeling electron emission and by using vanes make from polished stainless steel in place of aluminum vanes 相似文献
97.
Zilla Sinuany-Stern Simona Cohen-Kadosh Lea Friedman 《Central European Journal of Operations Research》2016,24(4):853-876
The purpose of this paper is to study the effect of the socio-economic status of patients on the efficiency of orthopedic wards in acute hospitals in Israel (20 hospitals), from the viewpoint of the regulator—Israel Ministry of Health. At the first stage, data envelopment analysis is used with two inputs, and three outputs, where one output is undesirable—“number of deaths”—which also reflects the quality of the health services. At the second stage, various nonparametric tests are utilized to test the relationship between the socio-economic status of patients and the efficiency. As by-product DEA provides benchmark analysis, which indicates the peers of each inefficient ward, and the I/O improvements are needed for achieving efficiency. Two versions of DEA were used: the output oriented version (variable returns to scale), and the non-oriented version (Additive). Further analysis provides comparison of the results with other simple efficiency measures. We also compare between the efficiency from the regulator viewpoint and the hospitals’ viewpoint. 相似文献
98.
Ye T Kaur R Senguen FT Michel LV Bren KL Elliott SJ 《Journal of the American Chemical Society》2008,130(21):6682-6683
Protein film voltammetry (PFV) is used to interrogate the behavior of a variety of bacterial and mitochondrial His/Met-ligated cytochromes c. While analogous studies upon alkanethiol-modified gold electrodes reveal the anticipated Fe(II/III) couple only, PFV using pyrolytic graphite edge (PGE) electrodes demonstrates the presence of a lower-potential form of each of the cyts c studied, with a potential of approximately -100 mV (vs hydrogen). The generation of the novel, lower-potential state is shown to arise specifically from the interaction with the PGE electrode. Simultaneously, the typical Fe(II/III) couple can be observed. PFV of a series of wild-type cytochromes and mutants in the Met-donating loop show that the lower-potential state is highly similar between proteins from Pseudomonas aeruginosa (PA), Hydrogenobacter thermophilus (HT), and horse heart. The generation of the lower-potential form correlates inversely with the stability of the Met-Fe interaction for each of the cytochromes. Comparison with chemically unfolded cyts c indicates that the lower-potential forms detected here are unique, and this distinct state is ascribed to the loss of the Met ligand. Thus, PGE is demonstrated to be a non-innocent electrode surface in PFV studies of His/Met-ligated cytochromes c. 相似文献
99.
Coriani S Høst S Jansík B Thøgersen L Olsen J Jørgensen P Reine S Pawłowski F Helgaker T Sałek P 《The Journal of chemical physics》2007,126(15):154108
A linear-scaling implementation of Hartree-Fock and Kohn-Sham self-consistent field theories for the calculation of frequency-dependent molecular response properties and excitation energies is presented, based on a nonredundant exponential parametrization of the one-electron density matrix in the atomic-orbital basis, avoiding the use of canonical orbitals. The response equations are solved iteratively, by an atomic-orbital subspace method equivalent to that of molecular-orbital theory. Important features of the subspace method are the use of paired trial vectors (to preserve the algebraic structure of the response equations), a nondiagonal preconditioner (for rapid convergence), and the generation of good initial guesses (for robust solution). As a result, the performance of the iterative method is the same as in canonical molecular-orbital theory, with five to ten iterations needed for convergence. As in traditional direct Hartree-Fock and Kohn-Sham theories, the calculations are dominated by the construction of the effective Fock/Kohn-Sham matrix, once in each iteration. Linear complexity is achieved by using sparse-matrix algebra, as illustrated in calculations of excitation energies and frequency-dependent polarizabilities of polyalanine peptides containing up to 1400 atoms. 相似文献
100.
Sałek P Høst S Thøgersen L Jørgensen P Manninen P Olsen J Jansík B Reine S Pawłowski F Tellgren E Helgaker T Coriani S 《The Journal of chemical physics》2007,126(11):114110
A linear-scaling implementation of Hartree-Fock and Kohn-Sham self-consistent field (SCF) theories is presented and illustrated with applications to molecules consisting of more than 1000 atoms. The diagonalization bottleneck of traditional SCF methods is avoided by carrying out a minimization of the Roothaan-Hall (RH) energy function and solving the Newton equations using the preconditioned conjugate-gradient (PCG) method. For rapid PCG convergence, the Lowdin orthogonal atomic orbital basis is used. The resulting linear-scaling trust-region Roothaan-Hall (LS-TRRH) method works by the introduction of a level-shift parameter in the RH Newton equations. A great advantage of the LS-TRRH method is that the optimal level shift can be determined at no extra cost, ensuring fast and robust convergence of both the SCF iterations and the level-shifted Newton equations. For density averaging, the authors use the trust-region density-subspace minimization (TRDSM) method, which, unlike the traditional direct inversion in the iterative subspace (DIIS) scheme, is firmly based on the principle of energy minimization. When combined with a linear-scaling evaluation of the Fock/Kohn-Sham matrix (including a boxed fitting of the electron density), LS-TRRH and TRDSM methods constitute the linear-scaling trust-region SCF (LS-TRSCF) method. The LS-TRSCF method compares favorably with the traditional SCF/DIIS scheme, converging smoothly and reliably in cases where the latter method fails. In one case where the LS-TRSCF method converges smoothly to a minimum, the SCF/DIIS method converges to a saddle point. 相似文献