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921.
The one-dimensional Klein-Gordon equation is solved for the PT-symmetric generalized Hulthén potential in the scalar coupling scheme. The relativistic bound-state energy spectrum and the corresponding wave functions are obtained by using the Nikiforov-Uvarov method which is based on solving the second-order linear differential equations by reduction to a generalized equation of hypergeometric type. PACS numbers: 03.65.Fd, 03.65.Ge  相似文献   
922.
This paper is a contribution to the problem of particle localization in non-relativistic Quantum Mechanics. Our main results will be (1) to formulate the problem of localization in terms of invariant subspaces of the Hilbert space, and (2) to show that the rigged Hilbert space incorporates particle localization in a natural manner.  相似文献   
923.
We prove the existence of an invariant measure for a large class of random processes with discrete time without assuming their linearity. Our main examples are “processes with variable length”, in which components may appear and disappear in the course of functioning. One of these examples displays non-uniqueness of invariant measure in a 1-D process.  相似文献   
924.
The classical Fisher information is superadditive in the sense that the Fisher information of a bivariate probability density is always not less than the sum of those of the marginals. The longstanding conjecture concerning the superadditivity of the Wigner–Yanase–Dyson information is a quantum analogue of this property. It is remarkable that Hansen constructed a numerical counterexample to the quantum case (J. Stat. Phys. 126: 643–648, 2007). However, the requirement of superadditivity of an information-theoretic quantity such as the Wigner–Yanase–Dyson information seems so intuitive, it is desirable to identify conditions as general as possible such that the superadditivity holds. In this paper, we establish the superadditivity in several physically significant cases.  相似文献   
925.
The conservation of translation as a symmetry in two-dimensional systems with interaction is a classical subject of statistical mechanics. Here we establish such a result for Gibbsian particle systems with two-body interaction, where the interesting cases of singular, hard-core and discontinuous interaction are included. We start with the special case of pure hard core repulsion in order to show how to treat hard cores in general.  相似文献   
926.
We previously reported that a deletion mutant (P478) with a residue Arg deleted at the C terminus of d-hydantoinase (P479) from Pseudomonas putida YZ-26 was dissociated into the monomer from its dimeric state. Based on the above result, a series of mutants of the enzyme with the C-terminal residues either deleted or substituted were prepared. The size-exclusion chromatography and bioactivity assay show that a C-terminal-substituted enzyme (R479D) and several truncated mutants (P478, P477, P476, and P475) are dissociated into the monomeric state as well, but their activities are largely retained. In contrast, two other mutants (R474 and R479A) are expressed in the form of random aggregates without any activity. Our experiments demonstrate that only the last four amino acids (-PVQR) at the C terminus of the enzyme can be deleted without seriously affecting its activity, although the enzyme is dissociated from a dimer into a monomer. These mutants also reveal some unique properties such as the enzymatic activity in vivo or in vitro, the effect of divalent metal ions, and the thermostability etc. in comparison to wild-type enzyme (P479). In addition, the three-dimensional structural modeling shows that the intact structure of the enzyme is essential, and the flexibility of the non-conservative region at the C terminus of the enzyme is quite limited.  相似文献   
927.
Resonance Raman spectra of oxygenated and deoxygenated functional erythrocytes recorded using 785 nm laser excitation are presented. The high-quality spectra show a mixture of enhanced A1g, A2g, B1g, B2g, Eu and vinyl modes. The high sensitivity of the Raman system enabled spectra from four oxygenation and deoxygenation cycles to be recorded with only 18 mW of power at the sample over a 60-minute period. This low power prevented photo-/thermal degradation and negated protein denaturation leading to heme aggregation. The large database consisting of 210 spectra from the four cycles was analyzed with principal components analysis (PCA). The PC1 loadings plot provided exquisite detail on bands associated with the oxygenated and deoxygenated states. The enhancement of a band at 567 cm−1, observed in the spectra of oxygenated cells and the corresponding PC1 loadings plot, was assigned to the Fe–O2 stretching mode, while a band appearing at 419 cm−1 was assigned to the Fe–O–O bending mode based on previous studies. For deoxygenated cells, the enhancement of B1g modes at 785 nm excitation is consistent with vibronic coupling between band III and the Soret transition. In the case of oxygenated cells, the enhancement of iron-axial out-of-plane modes and non-totally symmetric modes is consistent with enhancement into the y,z-polarized transition centered at 785 nm. The enhancement of non-totally symmetric B1g modes in oxygenated cells suggests vibronic coupling between band IV and the Soret band. This study provides new insights into the vibrational dynamics, electronic structure and resonant enhancement of heme moieties within functional erythrocytes at near-IR excitation wavelengths. Part of this work was first presented at SPEC 2006, Shedding New Light on Disease: Optical Diagnosis for the New Millennium, held at Heidelberg, Germany, on 20–24 May 2006.  相似文献   
928.
The purpose of this study was to evaluate the physical–chemical properties of collagen (CL) and usnic acid/collagen-based (UAC) films, using differential thermal analysis (DTA), thermogravimetry (TG/DTG), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Both films were prepared by casting process using polyethylene glycol 1500 (PEG 1500) as plasticizer. In the spectrum of UAC, similar bands of the usnic acid are observed, indicating that the polymerization (film formation) did not affect the stability of the drug. Distinctly, DTA curve of UAC did not show an endothermic peak at 201 °C, indicative that the drug was incorporated into the polymeric system. These results were corroborated by the scanning electron microscopy (SEM). The TG/DTG curves of UAC presented a different thermal decomposition profile compared to the individual compounds and CL. These findings suggest the occurrence of molecular dispersion or solubilization of the drug in the collagen film.  相似文献   
929.
In this study, we describe a method for highly specific enrichment of phosphopeptides with multifunctional chitosan–glycidyl methacrylate (GMA)–iminodiacetic acid (IDA)–Fe (III) nanospheres for direct analysis by matrix-assisted laser desorption–ionization mass spectrometry (MALDI-MS). This is the first time that chitosan has been used to create nanospheres support material for selective enrichment of phosphopeptides by modification with GMA, derivatization with IDA, and loading with Fe (III) ions. Chitosan-GMA-IDA-Fe (III) nanospheres with a diameter of 20 to 100 nm have multifunctional chemical moieties which confer unique properties, good dispersibility in highly acidic binding buffers, as well as good biocompatibility and chemical stability which improves their specific interaction with phosphopeptides using various types of acid binding buffers. The process of enrichment is very simple, quick, efficient, and specific. Its high specificity and efficiency for purification of phosphopeptides is reflected in the very low and substoichiometric amounts of phosphopeptides which can be detected, in quantities as low as 1:3,000 M ratios. Compared with other state-of the-art technologies such as the use of conventional Fe3+-IMAC and TiO2, these chitosan nanosphere techniques show superior specificity and sensitivity. Moreover, the resultant chitosan-GMA-IDA-Fe3+ nanosphere-absorbed phosphopeptides can be either directly analyzed by MALDI-TOF MS analysis or eluted and further analyzed by nano-LC-MS/MS.  相似文献   
930.
An electrospray ionization (ESI) ambient pressure ion-mobility spectrometer (APIMS) interfaced to an orthogonal reflector time-of-flight mass spectrometer (TOFMS) was evaluated for the first time as a detector for the identification of phenylthiohydantoin (PTH)-derivatized amino acids, the final products in the Edman sequencing process of peptides and proteins. The drift and flight times of the twenty common PTH amino acids were characterized by a well-defined 2-D mobility/mass spectral pattern. The combination of mobility/mass modes of analysis gave rise to a unique trend-line formation for the series of PTH amino acids. In addition, each PTH amino acid had a unique reduced mobility constant K(o), thus enabling the differentiation of all the amino acid derivatives including the PTH-leucine and PTH-isoleucine isomers. More importantly it was shown that it was possible to resolve a complete reference mixture of PTH amino acids in a single experimental run in less than 1 min. Detection limits for the PTH amino acids were found to range from 1.04 to 3.52 ng; indicating that the limits of detection were less than 17.0 pmol for all of the PTH amino acids.  相似文献   
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