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911.
Yutaka Ishigami Fumiyoshi Ishii Young Kook Choi Toshio Kajiuchi 《Colloids and surfaces. B, Biointerfaces》1996,7(5-6):215-220
Fluorescent probes are useful to monitor the polarity and fluidity of microenvironments. Therefore, a new amphiphilic fluorescent probe, the pyrenacylester of Rhamnolipid B, was prepared from biosurfactant (Rhamnolipid B) and pyrene. As a result of its surface activity, this probe was expected to be able to penetrate into various kinds of microdomains such as the environments of organic solvents, emulsions, dispersions, surfaces of biomembranes and polymers. 相似文献
912.
We propose an improved conformal mapping technique for analytical calculation of two-dimensional profiles of the nematic liquid crystal (NLC) director in a cell with a simply connected cross-sectional region. We consider the case of the strong anchoring and the piecewise constant director pretilt on the piecewise smooth curve which bounds the region. Obtained expressions for the director profile explicitly depend on the conformal mapping which maps the region onto the upper half plane of a complex plane. An advantage of our method in comparison with the standard conformal mapping technique is that it does not require the knowledge of the inverse mapping and the calculation of the integral in the Poisson formula. Proposed technique allows to take into account topological defects in the bulk of the NLC on the symmetry axis of the region. As an example of how the method can be used, we find an analytical expression for the director profile in a horizontal cylindrical groove partly filled with the NLC. We consider the case where a disclination line parallel to the axis of the groove occurs in the bulk of the NLC. The equilibrium position of the disclination line is found. 相似文献
913.
Summary In recent biochemical studies it was demonstrated that residue Asp113 of the-adrenoceptor (-AR) is an indispensable amino acid for the binding of-AR antagonists. Earlier fluorescence studies showed that a tryptophan-rich region of the-AR is involved in the binding of propranolol, the prototype-AR antagonist. Bearing these two biochemical findings in mind, we explored the-AR part containing Asp113, for an energetically favorable antagonist binding site. This was done by performing molecular docking studies with the antagonist propranolol and a specific-AR peptide which included, besides Asp113, two possibly relevant tryptophan residues. In the docking calculations, the propranolol molecule was allowed to vary all its internal torsional angles. The receptor peptide was kept in an-helix conformation, while side chains relevant to ligand binding were flexible to enable optimal adaptations to the ligand's binding conformation. By means of force-field calculations the total energy was minimized, consisting of the intramolecular energies of both ligand and receptor peptide, and the intermolecular energy. We found an antagonist binding site, consisting of amino acids Asp113 and Trp109, which enabled energetically favorable interactions with the receptor-binding groups of propranolol. According to these results, binding involves three main interaction points: (i) a reinforced ionic bond; (ii) a hydrogen bond; and (iii) a hydrophobic/charge transfer interaction. The deduced binding site shows a difference in affinity between the levo- and dextrorotatory isomers of propranolol caused by a difference in ability to form a hydrogen bond, which is in conformity with the experimentally observed stereoselectivity. Moreover, it also provides an explanation for the
1-selectivity ofp-phenyl substituted phenoxypropanolamines like betaxolol. Thep-phenyl substituent of betaxolol was shown to be sterically hindered upon binding to the
2-AR peptide, whereas this hindrance is very likely to be much less with the
1-AR peptide. Finally, the proposed antagonist binding site is discussed in the light of some recent biochemical findings and theories.Abbreviations
-AR
-adrenergic receptor
- cDNA
complementary DNA
- H-bond
hydrogen bond
- VdW
van der Waals
- QSAR
quantitative structure-activity relationship
-
125I-pBABC
p-(bromoacetamido)benzyl-1-[125I]iodocarazol 相似文献
914.
Abstract The combined use of the nonlinear mapping method with correspondence factor analysis allowed to derive interesting structure-chemoreception relationships in Lepidoptera. A chemotaxonomy of insects based on their responses to pheromones was also proposed. 相似文献
915.
916.
M. OKABE 《International Journal of Computational Fluid Dynamics》2013,27(1-2):179-191
The unified theory in infinite elementology is presented in one to three dimensions so that developed infinite elements are C° conformably connected with the isoparametric finite elements. It is further shown that the infinity mapping technology is easily incorporated into general finite element codes. 相似文献
917.
Crystal orientation measurements made by electron backscattered diffraction (EBSD) in the scanning electron microscope (SEM)
and microscopic observations provided the basis for a quantitative investigation of microstructure in an yttria stabilised,
tetragonal zirconia-based (Y-TZP) composite. Automatic crystal orientation mapping (ACOM) in a SEM can be preferable to transmission
electron microscopy (TEM) for microstructural characterisation, since no sample thinning is required, extensive crystal data
is already available, and the analysis area is greatly increased. A composite with a 20 vol.% tungsten carbide (WC) content
was chosen since it revealed crystal relationships between the matrix and carbide phase already established by TEM analysis.
However, this composite was difficult to investigate in the EBSD/ SEM since it is non-conductive, the Y-TZP grain size is
of the order of the system resolution, and the sample surface, though carefully prepared, reveals a distinctive microtopography.
In this paper, some useful solutions to these problems are discussed and the resulting data, which confirm crystal correlations
previously established by TEM analysis, are presented. 相似文献
918.
Guohua Tao 《Chemphyschem》2019,20(16):2127-2135
Diffusion of atomic hydrogen on metallic surfaces is a longstanding research topic of both fundamental and practical interests. However, full understanding of the microscopic mechanisms and development of effective strategy for surface dynamics control at the molecular level remain elusive. In this paper, we propose a new nonadiabatic multistate model for surface diffusion based on a real space decomposition scheme by generalizing the classical mapping theory of Meyer and Miller. The model suggests a general multistate perspective on real-time surface dynamics by mapping it into spatially disjointed windowing functions, which feature the explicit nonadiabatic controllability. Within this framework, the first nonadiabatic molecular dynamics simulation is performed for atomic hydrogen diffusion on the Cu(001) surface, and the nonequilibrium effect of lattice distortion is studied. 相似文献
919.
X-ray mapping using energy dispersive spectroscopy or wavelength dispersive spectroscopy is a very popular characterisation
tool for determining the elemental distribution in materials. Furthermore, quantitative X-ray mapping has become a very powerful
technique enabling reliable quantitative results that can be an order of magnitude better than traditional analysis. Quantitative
X-ray mapping is also far superior to regions of interest X-ray maps where low levels of an element or elemental overlaps
are present.
The one major drawback with X-ray mapping is the time required to obtain a high resolution X-ray map with good statistics
at low levels of concentration. The use of multi-detectors, and just developed dual turret detectors for X-ray mapping, allows
improvement in performance at low levels without compromising quantification quality and precision of traces, even in the
presence of overlaps. However, for quantitative X-ray mapping to work properly, the characteristics of each detector must
be accurately determined so that the final quantification of the individual detectors can be summed. To accomplish this effectively,
the full spectrum at each pixel for each energy dispersive detector should be saved. As a final check for consistency between
detectors, a technique was developed that involves assigning a different red-green-blue colour for each detector for the same
element. By doing this, when we combine the three maps of the same element, we should obtain a grey scale map that indicates
total correlation between the three detectors at the most critical final stage of quantification. To reduce contrast noise
and further improve the quality of quantitative X-ray mapping images, a filter referred to as a “speckle filter” has been
developed that allows the eye to see a more correct elemental concentration relationship. 相似文献
920.
Lingyu Wang Jianhui Cheng Julie E. McNutt Gregg B. Morin David D. Y. Chen 《Electrophoresis》2020,41(21-22):1832-1842
Dynamic pH barrage junction focusing in CE enables effective signal enhancement, quantitative capture efficiencies, and straightforward optimization. The method is a technical variant of dynamic pH junction focusing. CE separation with dynamic pH barrage junction focusing is compatible with both optical and mass spectrometric detection. We developed a CE–MS/MS method using hydrophilic polyethyleneimine-coated capillaries and validated it for the qualitative analysis of amino acids, peptides, and tryptic peptides of digested monoclonal antibodies. The S/N of extracted ion electropherograms of zwitterionic analytes were enhanced by approximately two orders of magnitude with a tradeoff of a shortened separation window. Online focusing improved the MS signal intensity of a diluted antibody digest, enabling more precursor ions to be analyzed with subsequent tandem mass spectrometric identification. It also broadened the concentration range of protein digest samples for which adequate sequence coverage data can be obtained. With only 0.9 ng of digested infliximab sample loaded into the capillary, 76% and 100% sequence coverage was realized for antibody heavy and light chains, respectively, after online focusing. Full coverage was achieved with 9 ng of injected digest. 相似文献