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排序方式: 共有309条查询结果,搜索用时 31 毫秒
31.
Pervin Deveci Bilge Taner Safaa Hashım Mohammed Albayatı 《Journal of inclusion phenomena and macrocyclic chemistry》2017,88(1-2):15-26
This study investigated inclusion formation and the physicochemical properties of naringin/cyclodextrin through a combined computational and experimental approach. Molecular dynamics simulations were applied to investigate the thermodynamics and geometry of naringin/cyclodextrin cavity docking. The complexes were investigated by UV, FT-IR, DSC, XRD, SEM, 2D-NOSEY and 1H-NMR analyses. Clearly visible protons belonging to naringin and chemical shift displacements of the H3 and H5 protons in cyclodextrin were anticipated in the formation of an inclusion complex. Naringin solubility increased linearly with increasing cyclodextrin concentration (displaying an AL profile). The simulations indicated that the phenyl group of naringin was located deep within the cyclodextrin cavity, while the glycoside group of naringin was on the plane of the wider rim of cyclodextrin. The simulation and molecular modeling results indicate that (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) provided the more stable inclusion complex. This result was also in good concordance with the stability constants that had been determined by the phase solubility method. The consistency of the computational and experimental results indicates their reliability. 相似文献
32.
Designing Excited States: Theory‐Guided Access to Efficient Photosensitizers for Photodynamic Action
33.
Finite difference equations can be used to study the responses of biochemical chain reactions at any step of the chain to
an external stimulus. In this study, we developed mathematical models for two hypothetical chain reactions involving loops
to study the responses in the chain as the length of the chain gets longer, so called transient and steady state responses.
The first model is for a chain with a negative feedforward loop, and the second one is for a chain that has a negative feedback
loop. Although both of the models have the same steady state equations and values, we showed that the chain with negative
feedforward and negative feedback loops can produce significantly different behaviors. The former can bring the chain into
oscillations with various periods and eventually chaos when the feedback is strong enough as the length of the reaction chain
increases, whereas the latter is not capable of producing oscillations and more complicated dynamics. 相似文献
34.
Yildirim G Zalaoglu Y Kirilmis C Koca M Terzioglu C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):104-110
This study deals with the identification of a title compound, 2,6-dimethyl-4-nitropyridine N-oxide by means of theoretical calculations. The optimized molecular structures, vibrational frequencies, corresponding vibrational assignments, thermodynamic properties and atomic charges of the title compound in the ground state were evaluated using density functional theory (DFT) with the standard B3LYP/6-311G(d,p) method and basis set combination for the first time. Theoretical vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results show that the optimized geometric parameters (bond lengths and bond angles) and vibrational frequencies were observed to be in good agreement with the available experimental results. Based on the results of comparison between experimental results and theoretical data, the chosen calculation level is powerful approach for understanding the molecular structures and vibrational spectra of the 2,6-dimethyl-4-nitropyridine N-oxide. Moreover, we not only simulated frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP) but also determined the transition state and energy band gap. Based on the investigations, the title compound is found to be useful to bond metallically and interact intermolecularly. Infrared intensities and Raman activities were also reported. 相似文献
35.
We obtain the spectra and fine spectra for factorable triangular matrices. Our results contain some previous work of the authors as special cases. 相似文献
36.
We obtain the spectra and fine spectra for factorable matrices, considered as bounded linear operators over ℓp , 1 < p < ∞. 相似文献
37.
H. Sinan
zkan Taner Oskay H. Yüksel Güney Hüseyin Dirim 《Journal of Polymer Science.Polymer Physics》1994,32(4):631-640
The mechanical anisotropy of a material obtained by stratification of oriented polyvinyl chloride (PVC) layers in different ways has been studied. PVC layers, uniaxially oriented by drawing each with a different draw ratio, were stratified in such a way that their draw axes were either parallel or perpendicular. The propagation velocities of ultrasonic pulses were measured in three principal planes defined by draw axes of the stratified material. With an immersion technique, measurements were performed at 2 MHz and 22°C. Experimentally, it was shown that while stratification of layers with draw axes parallel preserves hexagonal symmetry, the stratified material with layers' draw axes perpendicular possesses orthorhombic symmetry. © 1994 John Wiley & Sons, Inc. 相似文献
38.
Electronically selective chemical functionalization of carbon nanotubes: correlation between Raman spectral and electrical responses 总被引:1,自引:0,他引:1
Wang C Cao Q Ozel T Gaur A Rogers JA Shim M 《Journal of the American Chemical Society》2005,127(32):11460-11468
Single-walled carbon nanotubes (SWNTs) demonstrate remarkable electronic and mechanical properties useful in developing areas such as nanoelectromechanical systems and flexible electronics. However, the highly inhomogeneous electronic distribution arising from different diameters and chirality in any given as-synthesized SWNT samples imposes severe limitations. Recently demonstrated selective chemical functionalization methods may provide a simple scalable means of eliminating metallic tubes from SWNT transistors and electronic devices. Here, we report on combined electron transport and Raman studies on the reaction of 4-bromobenzene diazonium tetrafluoroborate directly with single and networks of SWNT transistors. First, Raman studies are carried out on isolated individual SWNTs grown on SiO2/Si substrates by chemical vapor deposition with and without metal contacts. Metallic tubes are found to have, on average, higher reactivity toward diazonium reagents. However, a considerable degradation of electrical properties of semiconducting tubes occurs if the reaction is carried out to the point where the conductivity of metallic tubes is significantly suppressed. Insights from single-tube studies are then applied to elucidate the electrical and the Raman responses of SWNT random network transistors of different channel lengths to chemical functionalization. 相似文献
39.
The 1H-pyrazole-3-carboxylic acid 2 was converted in good yield (69%) into the corresponding 1H-pyrazole-3-carboxamide 5 via reaction of the acid chloride 3 with 2,3- diaminopyridine (4). A different product, the 3H-imidazo[4,5-b] pyridine derivative 6, was formed from the reaction of 3 with 4 and base in benzene for 5 hours. The structures of the synthesized compounds were determined spectroscopically. The mechanism of the reaction between 3 and 4 was examined theoretically. 相似文献
40.
From first-principles calculations, we predict that a single ethylene molecule can form a stable complex with two transition metals (TM) such as Ti. The resulting TM-ethylene complex then absorbs up to ten hydrogen molecules, reaching to gravimetric storage capacity of approximately 14 wt %. Dimerization, polymerizations, and incorporation of the TM-ethylene complexes in nanoporous carbon materials are also discussed. Our results are quite remarkable and open a new approach to high-capacity hydrogen-storage materials discovery. 相似文献