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51.
Menon S Vaidya H Pillai S Vidya R Mitscher LA 《Combinatorial chemistry & high throughput screening》2003,6(5):471-480
A solution phase strategy for the multiple parallel synthesis of a demonstration library of indazoles is described by which regio-selectivity problems inherent to previous syntheses of this nucleus are largely overcome. Synthesis of selected components proceeded satisfactorily indicating that a fully realized library of indazole analogs could readily be produced using this methodology. Simple modifications of the basic nucleophilic aromatic substitution route unambiguously produce a range of N-1 substitutions (alkyl, aryl and aralkyl) in 50-75% yields. Next a range of substituents was introduced at the C-3 position in 50-80% yields by O-alkylation. Careful choice of reagents and reaction conditions were required to prevent by-product formation due to competing alkylation at N-2 (trace to 15% yields). When present, these contaminants were readily removed by chromofiltration. A third diversity site was sketched in at C-5 in 75-90% yield by reductive alkylation or acylation. Screening of some of the demonstration library members in vitro revealed highly active antioxidants suggesting that producing a full library would be worthwhile. 相似文献
52.
Himadri R. Soni Venu Mankad Sanjay D. Gupta Sanjeev K. Gupta Prafulla K. Jha 《Journal of Thermal Analysis and Calorimetry》2012,107(1):39-44
In the present paper, we report an ab initio calculation of the ground state, electronic and thermodynamical properties like
constant volume lattice specific heat, vibrational energy, internal energy, and entropy for GaP and Ga2P is presented. These properties are obtained after calculating the phonon spectrum over the entire Brillouin zone. The calculations
were performed using the ABINIT program package, which is based on density functional theory (DFT) method and the use of pseudopotentials
and plane wave expansion. Difference in the ground state properties such as electronic structure and thermodynamical properties
are discussed. The thermodynamical properties follow the expected trend. There is a good agreement between present theoretical
and limited available experimental data in the case of ground state such as lattice constant and bulk modulus and electronic
properties. With the increase of Ga atoms in the unit cell the semiconducting nature of Ga2P turns to metallic. There is a noticeable difference in the thermodynamical properties in the case of both gallium compounds. 相似文献
53.
Treatment of [PtCl2(Ptolyl3)2] (tolyl = 4-MeC6H4) with Na2S in benzene gave [Pt2(μ2-S)2(Ptolyl3)4] (1), which is soluble in common organic solvents. Reactions of (1) with various metal complexes have been studied and several polynuclear metal aggregates isolated. These new complexes were
characterized by elemental analysis and n.m.r. spectroscopy.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
54.
Low‐temperature sol–gel transformation of methyl silicon precursors to silica‐based hybrid materials
Veena Dhayal Rakesh Bohra Meena Nagar Ajay Kaushik Sanjay Mathur Sven Barth 《应用有机金属化学》2008,22(11):629-636
Six new methyl silicon (IV) precursors of the type [MeSi{ON?C(R)Ar}3] [when R = Me, Ar = 2‐C5H4N ( 1 ), 2‐C4H3O ( 2 ) or 2‐C4H3S ( 3 ); and when R = H, Ar = 2‐C5H4N ( 4 ), 2‐C4H3O ( 5 ) or 2‐C4H3S ( 6 )] were prepared and structurally characterized by various spectroscopic techniques. Molecular weight measurements and FAB (Fast Atomic Bombardment) mass spectral studies indicated their monomeric nature. 1H and 13C{1H} NMR spectral studies suggested the oximate ligands to be monodentate in solution, which was confirmed by 29Si{1H} NMR signals in the region expected for tetra‐coordinated methylsilicon (IV) derivatives. Thermogravimetric analysis of 1 revealed the complex to be thermally labile, decomposing to a hybrid material of definite composition. Two representative compounds ( 2 and 4 ) were studied as single source molecular precursor for low‐temperature transformation to silica‐based hybrid materials using sol–gel technique. Formation of homogenous methyl‐bonded silica materials (MeSiO3/2) at low sintering temperature was observed. The thermogravimetric analysis of the methylsilica material indicated that silicon‐methyl bond is thermally stable up to a temperature of 400 °C. Reaction of 2 and Al(OPri)3 in equimolar ratio in anhydrous toluene yielded a brown‐colored viscous liquid of the composition [MeSi{ON?C(CH3)C4H3O}3.Al(OPri)3]. Spectroscopic techniques 1H, 13C{1H}, 27Al{1H} and 29Si{1H} NMR spectra of the viscous product indicated the presence of tetracoordination around both silicon and aluminum atoms. On hydrolysis it yielded methylated aluminosilicate material with high specific surface area (464 m2/g). Scanning electron micrography confirmed a regular porous structure with porosity in the nanometric range. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
55.
Periodic orbits belonging to the stromgren families A, B and C around the collinear libration points in the restricted three
body problem have been studied when the smaller primary is a triaxial rigid body and more massive body is a source of radiation
pressure. These families are determined in three different cases: (i) classical case, (ii) when bigger primary is a source
of radiation pressure, (iii) when smaller primary is a triaxial rigid body and bigger primary is a source of radiation pressure.
The Liapunov stability of each periodic solution has also been examined.
相似文献
56.
Subhendu Bhowmik Garima Pandey Dr. Sanjay Batra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10487-10491
57.
Rahul Bhatt Sanjay K. Mishra D. Mohan A.K. Gupta 《Optics and Lasers in Engineering》2008,46(6):428-439
A fast holographic wavefront sensor is proposed using a computer-generated hologram (CGH). This CGH is a multiplexed hologram of different Zernike mode–amplitude combinations, and is designed in such a manner as to get the corresponding spots on the detector according to the presence and strength of a particular aberration. Interference between the aberrated wavefront (with a single mode–amplitude combination) and the Fourier transform of an image with single bright pixel (defined as dot image) is numerically calculated for one hologram. Different mode–amplitude combination and corresponding different positions of bright pixels (dots) are taken to compute various holograms and then all the holograms are multiplexed to get the final hologram. When the aberrated wavefront with a particular mode–amplitude combination is incident onto the multiplexed hologram, the corresponding dot is generated in the Fourier plane. A lens performs the Fourier transform in optical domain and provides the instant detection of amplitude of the respective Zernike mode. The main advantage of the scheme is to avoid the need of any computations, which makes it really fast. The simulation results are presented with the cross-talk analysis for few Zernike terms. 相似文献
58.
In a production system, rework process plays an important role in eliminating waste and effectively controlling the cost of manufacturing. Determining the optimal batch size in a system that allows for rework is, therefore, a worthwhile objective to minimize the inventory cost of work-in-processes and the finished goods. In this paper, models for the optimum batch quantity in a multi-stage system with rework process have been developed for two different operational policies. Policy 1 deals with the rework within the same cycle with no shortage and policy 2 deals with the rework done after N cycles, incurring shortages in each cycle. The major components that play a role in minimizing this cost of the system are manufacturing setups, work-in-processes, storage of finished goods, rework processing, waiting-time, and penalty costs to discourage the generation of defectives. The mathematical structure of this rework processing model falls under a nonlinear convex programming problems for which a closed-form solution has been proposed and results are demonstrated through numerical examples, followed by sensitivity analyses of different important parameters. It is concluded that the total cost in policy 2 tends to be smaller than that in policy 1 at lower proportion of defectives if the in-process carrying cost is low. Policy 2 may be preferred when the work-in-process carrying cost is low and the penalty cost is negligible. 相似文献
59.
Sanjay K. Bharti Saurabh K. Patel Gopal Nath Ragini Tilak Sushil K. Singh 《Transition Metal Chemistry》2010,35(8):917-925
Six Cu(II) complexes of Schiff base ligands of arylidene-2-(4-(4-bromo/methoxy-phenyl)thiazol-2-yl) hydrazines have been synthesized,
characterized and screened for DNA cleavage and antimicrobial activities. The chemical structures of the complexes were deduced
by physicochemical and spectroscopic methods. Elemental analyses indicated that the stoichiometry of the complexes is CuL2 (L = Schiff base ligand). The DNA cleavage activities of the complexes were evaluated by agarose gel electrophoresis in the
presence and absence of oxidant (H2O2) and free radical scavenger (DMSO). All the six complexes showed significant nuclease activity in the presence of H2O2, and two of the complexes showed moderate nuclease activity even in the absence of oxidant. The complexes did not show nuclease
activity in the presence of free radical scavenger. The compounds were tested for activity against selected bacteria and fungi. 相似文献
60.
Sanjay S. Latthe Hiroaki Imai V. Ganesan Charles Kappenstein A. Venkateswara Rao 《Journal of Sol-Gel Science and Technology》2010,53(2):208-215
Optically transparent silica films were prepared at room temperature (~27°C) by keeping the molar ratio of TEOS:MeOH:H2O (0.001 M NH4F) constant at 1:19.29:6.20, respectively. A surface chemical modification of the films was done with alkylchlorosilanes at
different concentrations from 0 to 1 vol. % and aging times varied from half to 2 h. The DMCS and TMCS surface modified silica
films showed the static water contact angle of 146° and 162°, respectively. When the DMCS and TMCS modified films were cured
at temperatures higher than 240 and 275°C, respectively, the films became superhydrophilic. Further, the humidity study was
carried out at a relative humidity of 90% at 30°C temperature over 60 days. We characterized the water repellent silica films
by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, % of optical transmission,
humidity tests and contact angle measurements. 相似文献