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131.
Karthikeyan M Krishnan S Pandey AK Bender A 《Journal of chemical information and modeling》2006,46(2):452-461
The Internet is a comprehensive resource of chemical information which is at the same time largely unstructured. It provides a wealth of scientific information such as experimental data and requires a suitable automated data mining and analysis tool for its meaningful exploration. The Java based software presented here, ChemXtreme, is developed for harvesting chemical information from the Internet employing the Google API in combination with a distributed client/server text analysis architecture based on JavaRMI. It represents the first and until now the only toolkit for automated structured data retrieval from the Internet which is itself open source. ChemXtreme employs the "search the search engine" strategy, where the URLs returned from the search engine are analyzed further via textual pattern analysis. This process resembles the manual analysis of the hit list, where relevant data are captured and, by means of human intervention, are mined into a format suitable for further analysis. ChemXtreme on the other hand transforms chemical information automatically into a structured format suitable for storage in databases and further analysis and also provides links to the original information source. The query data retrieved from the search engine by the server is encoded, encrypted, and compressed and then sent to all the participating active clients in the network for parsing. Relevant information identified by the clients on the retrieved Web sites is sent back to the server, verified, and added to the database for data mining and further analysis. The distributed further analysis of URLs in a client/server architecture scales very favorably, thus producing only minimal overhead. 相似文献
132.
Siva Rama Krishnan Balaji Devarajan Mutharasu Subramani Shanmugan N. Sankara Subramanian Kulathu Ramanathan 《Ionics》2010,16(4):351-360
LiSmxMn2–xO4 samples were synthesized via co-precipitation technique. The structural properties of the synthesized materials were studied
using X-ray diffraction analysis and it confirmed the cubic spinel structure for all the compounds. The lattice parameter
of LiMn2O4 was observed to be 8.2347 Ǻ and it decreased with Sm3+ concentration, due to the shrinkage in cell volume aided by higher binding energy between Sm-O bond. The SEM micrographs
were analyzed using Image processing software (Image-J) to ascertain the pore and grain properties. The microwave synthesis
had been observed to control the bulk grain formation and had yielded lesser porous and nanoparticles. The particle size distributions
obtained through photocross correlation laser diffraction analysis had shown that LiMn2O4 with 60 nm and Sm-doped compounds with ∼30 nm, respectively. The cyclic voltammetry studies had revealed the decrease in
electrocatalytic behavior in the initial cycle for compounds doped with Sm3+ ion. The initial capacities of LiMn2O4, LiSm0.05Mn1.95O4 and LiSm0.10Mn1.90O4 substituted compounds were observed to be 134.87 mAhg−1, 132.22 mAhg−1 and 126.41 mAhg−1, respectively. The cells were simulated using 1D model namely Dualfoil5.1 program. The simulated results coincide well with
the measured results. The cycle life studies reveal 93% capacity retention of samarium-0.05-doped samples when compared with
78.4% of the LiMn2O4. 相似文献
133.
D. Banerjee S.V. Thakare R. Menon K. Krishnan 《Journal of Physics and Chemistry of Solids》2010,71(7):983-987
Phase transition from anatase to rutile for the 70 nm TiO2 crystallite has been investigated by the time differential perturbed angular correlation (TDPAC) technique. The study involved the annealing of the TiO2 nanocrystals, adsorbed with the nuclear probe (181Hf/181Ta) at trace level, at different temperatures for different durations. The TDPAC measurement was also supported by XRD measurement where the width of the peaks increases with the increase in annealing temperature indicating a crystal growth. The samples annealed up to 823 K for 4 h showed no phase transition, except for the growth of the crystallites. However, it showed phase transition at the same temperature (823 K), when annealed for longer duration, indicating the slower kinetics of the phase transition process. Further the sample, when annealed at 1123 K for 4 h, showed phase transition. It has also been observed that the 181Hf tracer, adsorbed on 70 nm anatase TiO2, diffuses from surface to bulk during the phase transition process and the extent of diffusion in anatase differs from that in rutile phase. However, surface to bulk mass-transfer is found to play a significant role in the phase transition process. 相似文献
134.
Reactive Pulsed Laser Deposition is a single step process wherein the ablated elemental metal reacts with a low pressure ambient gas to form a compound. We report here a Secondary Ion Mass Spectrometry based analytical methodology to conduct minimum number of experiments to arrive at optimal process parameters to obtain high quality TiN thin film. Quality of these films was confirmed by electron microscopic analysis. This methodology can be extended for optimization of other process parameters and materials. 相似文献
135.
Sambath Muniyagounder Balachandran Krishnan 《Journal of Applied Analysis & Computation》2013,3(1):71-80
In this paper, we investigate the spatiotemporal dynamics of a ratio-dependent predator-prey model with cross diffusion incorporating proportion of prey refuge. First we get the critical lines of Hopf and Turing bifurcations in a spatial domain by using mathematical theory. More specifically, the exact Turing region is given in a two parameter space. Also we perform a series of numerical simulations. The obtained results reveal that this system has rich dynamics, such as spotted, stripe and labyrinth patterns which show that it is useful to use the predator-prey model to reveal the spatial dynamics in the real world. 相似文献
136.
John W.Grove 《数学物理学报(B辑英文版)》2010,30(2):563-594
This article describes mathematical models for phase separated mixtures of materials that are in pressure and velocity equilibrium but not necessarily temperature equilibrium. General conditions for constitutive models for such mixtures that exhibit a single mixture sound speed are discussed and specific examples are described. 相似文献
137.
Modern quantum chemical methods can be used to investigate many properties of novel molecules and materials with predictive power. We have carried out accurate quantum chemical calculations with cluster models to investigate chemical reactions on semiconductor surfaces. The structure–property relationships that emerge from these studies are illustrated with particular emphasis on silicon as well as indium phosphide surface chemistry. Some new strategies that we have developed to provide a proper balance between covalent and dative bonding in compound semiconductors are discussed. Embedded cluster models have been used in some cases to include the effects of the surroundings on the active region. The structural and mechanistic understanding that emerges from our studies is illustrated by selected results on atomic layer deposition of Al2O3 on silicon and hydrogenation of P-rich and In-rich indium phosphide surfaces. 相似文献
138.
Polarity of the surrounding medium affects the excited states of UV-B sunscreens. Therefore understanding excited state processes
in a mixed polarity model system similar to skin is essential. We report the excited state lifetimes, quantum yields, radiative
and non-radiative rates of three sunscreens. Among the three UV-B sunscreens studied, octyl salicylate emits from a single
excited state, while padimate O and octyl methoxy cinnamate show multiple states. The radiative rates of salicylate and cinnamate
are approximately constant, while that of padimate O depends strongly on solvent. The non-radiative rates of all sunscreens
vary with solvent polarity. Compared to salicylate and cinnamate, padimate O is complex to analyze because of its two emission
peaks and one peak’s strong dependence on the dielectric constant. High absorbance, broad absorption peak with small fluorescence
quantum yield, and low radiative rate make octyl methoxy cinnamate a superior UV-B sunscreen ingredient. The complexity in
excited-state analysis shows that the lifetimes of the sunscreens are critical parameters, in addition to absorbance and quantum
yield. Fluorescence lifetime substantiates the use of polystyrene nanospheres as a model host to study the photo-physical
properties of sunscreen in a heterogeneous environment. 相似文献
139.
S. Krishnan C. Justin Raj S. M. Navis Priya R. Robert S. Dinakaran S. Jerome Das 《Crystal Research and Technology》2008,43(8):845-850
Single crystals of ferroelectric succinic acid (SA) with very high degree of transparency were grown from aqueous solution by slow evaporation technique. Single crystal X‐ray diffraction analysis reveals that the crystal belongs to monoclinic system with the space group P21/c. Some physical parameters have been determined for grown crystal. The optical absorption study reveals the transparency of the crystal in the entire visible region and the cut off wave length was found to be 240 nm. The optical band gap is found to be 3.75 eV. The dependence of extinction coefficient (k) and refractive index (n) on the wavelength have also been reported. The presence of functional groups was determined qualitatively by using Fourier transform infrared spectrum (FTIR) from which force constant has been calculated. The dielectric constant was also studied as a function of frequency at room temperature and electrical conductivity has been calculated from the Cole‐Cole plot. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
140.
Sujatha Asha Sasidharan Anjana Anns Maria Thomas Minu Elizabeth Thomas K. R. Rohit K. Keerthi Krishnan 《合成通讯》2019,49(2):256-265
In this study, we report a copper-catalyzed ligand-free Cadiot–Chodkiewicz coupling reaction. No additives or ligands are required for this Cu-catalyzed C(sp)–C(sp) coupling reaction of terminal alkynes with alkynyl halides. The low cost of copper catalyst, excellent yield of the products, suppression of side-products and mild reaction conditions are the major advantages of this protocol. 相似文献