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111.
R. Ramesh Babu K. Sethuraman N. Vijayan G. Bhagavannarayana R. Gopalakrishnan P. Ramasamy 《Crystal Research and Technology》2008,43(1):50-54
The bulk organic single crystal of phthalic anhydride (PA) was grown by vertical Bridgman technique. The structural perfection of the grown crystal was analysed by high resolution X‐ray diffraction (Multicrystal X‐ray diffractometry) studies. The thermal and mechanical properties have been studied. The second harmonic generation relative efficiency of Phthalic anhydride crystal is compared with KDP crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
112.
Amuthan Arunkumar Ramabathiran S. Gopalakrishnan 《Journal of Computational and Applied Mathematics》2012
An energy–momentum conserving time integrator coupled with an automatic finite element algorithm is developed to study longitudinal wave propagation in hyperelastic layers. The Murnaghan strain energy function is used to model material nonlinearity and full geometric nonlinearity is considered. An automatic assembly algorithm using algorithmic differentiation is developed within a discrete Hamiltonian framework to directly formulate the finite element matrices without recourse to an explicit derivation of their algebraic form or the governing equations. The algorithm is illustrated with applications to longitudinal wave propagation in a thin hyperelastic layer modeled with a two-mode kinematic model. Solution obtained using a standard nonlinear finite element model with Newmark time stepping is provided for comparison. 相似文献
113.
A Legendre spectral element model for sloshing and acoustic analysis in nearly incompressible fluids
D. Krishna Kishor S. Gopalakrishnan Ranjan Ganguli 《Journal of computational physics》2010,229(7):2605-2624
A new spectral finite element formulation is presented for modeling the sloshing and the acoustic waves in nearly incompressible fluids. The formulation makes use of the Legendre polynomials in deriving the finite element interpolation shape functions in the Lagrangian frame of reference. The formulated element uses Gauss–Lobatto–Legendre quadrature scheme for integrating the volumetric stiffness and the mass matrices while the conventional Gauss–Legendre quadrature scheme is used on the rotational stiffness matrix to completely eliminate the zero energy modes, which are normally associated with the Lagrangian FE formulation. The numerical performance of the spectral element formulated here is examined by doing the inf–sup test on a standard rectangular rigid tank partially filled with liquid. The eigenvalues obtained from the formulated spectral element are compared with the conventional equally spaced node locations of the h-type Lagrangian finite element and the predicted results show that these spectral elements are more accurate and give superior convergence. The efficiency and robustness of the formulated elements are demonstrated by solving few standard problems involving free vibration and dynamic response analysis with undistorted and distorted spectral elements, and the obtained results are compared with available results in the published literature. 相似文献
114.
Lajna P. Vijayan Bhakti V. Raigaonkar M.S. Qureshi R.N. Dubey M.M. Malik 《Journal of Electrostatics》2010,68(4):384-389
This paper reports the study of surface charge characteristics of bio-magnetoelectrets of amino acid l-serine. Electrets were prepared under the combined effect of heat and magnetic field. Three different forming temperatures and five different magnetic fields were used for the study. The bio-magnetoelectrets prepared this way were observed to have a surface charge of the order of 10?9 C. The decay of surface charge was studied continuously for 20 days and corresponding time constant was calculated. The comparative studies of surface charge characteristics were done by preparing bio-magnetoelectrets using homogeneous and inhomogeneous magnetic fields. 相似文献
115.
Sivakumar T Ramesha K Lofland SE Ramanujachary KV Subbanna GN Gopalakrishnan J 《Inorganic chemistry》2004,43(6):1857-1864
We describe the synthesis of two new quadruple perovskites, Sr(2)La(2)CuTi(3)O(12) (I) and Ca(2)La(2)CuTi(3)O(12) (II), by solid-state metathesis reaction between K(2)La(2)Ti(3)O(10) and A(2)CuO(2)Cl(2) (A = Sr, Ca). I is formed at 920 degrees C/12 h, and II, at 750 degrees C/24 h. Both the oxides crystallize in a tetragonal (P4/mmm) quadruple perovskite structure (a = 3.9098(2) and c = 15.794(1) A for I; a = 3.8729(5) and c = 15.689(2) A for II). We have determined the structures of I and II by Rietveld refinement of powder XRD data. The structure consists of perovskite-like octahedral CuO(4/2)O(2/2) sheets alternating with triple octahedral Ti(3)O(18/2) sheets along the c-direction. The refinement shows La/A disorder but no Cu/Ti disorder in the structure. The new cuprates show low magnetization (0.0065 micro(B) for I and 0.0033 micro(B) for II) suggesting that the Cu(II) spins are in an antiferromagnetically ordered state. Both I and II transform at high temperatures to 3D perovskites where La/Sr and Cu/Ti are disordered, suggesting that I and II are metastable phases having been formed in the low-temperature metathesis reaction. Interestingly, the reaction between K(2)La(2)Ti(3)O(10) and Ca(2)CuO(2)Cl(2) follows a different route at 650 degrees C, K(2)La(2)Ti(3)O(10) + Ca(2)CuO(2)Cl(2) --> CaLa(2)Ti(3)O(10) + CaCuO(2) + 2KCl, revealing multiple reaction pathways for metathesis reactions. 相似文献
116.
V.L. Rao P.U. Sabeena C. Gopalakrishnan P.V. Ravindran K.N. Ninan 《European Polymer Journal》2004,40(11):2645-2651
Polyether ether ketone and polyether ether ketone copolymers were prepared by the nucleophilic substitution reaction of 4,4′-difluorobenzophenone with hydroquinone and with varying mole proportions of hydroquinone and methyl hydroquinone using sulfolane solvent in the presence of anhydrous K2CO3. The polymers were characterised by different physico-chemical techniques. The crystallinity of the polymers was found to decrease with increase in concentration of the methyl hydroquinone units in the polymer. Thermogravimetric studies showed that all the polymers were stable upto 430 °C with a char yield above 49% at 900 °C in N2 atmosphere. The glass transition temperature was found to increase and the crystalline melting temperature and activation energy were found to decrease with increase in concentration of the methyl hydroquinone units in the polymer. 相似文献
117.
V. Kanagarajan J. Thanusu M. R. Ezhilarasi M. Gopalakrishnan 《Chemistry of Heterocyclic Compounds》2011,47(1):60-66
A novel approach towards the synthesis of spiropiperidinyl 1,2,4-triazolidine-3-thiones was proposed, exploiting microwave
activation coupled with solvent-free reaction conditions. In search for new leads towards potent antimicrobial agents, we
tested all the synthesized compounds for their in vitro antibacterial activity against Bacillus subtilis and Micrococcus luteus
and antifungal activity against Aspergillus niger, Candida albicans, Candida-6, and Candida-51. Two of the compounds exerted
strong in vitro antibacterial activity against B. subtilis and M. luteus, and all the synthesized compounds were potent against
the tested fungal strains. 相似文献
118.
119.
Dr. Priyankar Paira Mun Juinn Chow Gopalakrishnan Venkatesan Vamsi Krishna Kosaraju Dr. Siew Lee Cheong Karl‐Norbert Klotz Dr. Wee Han Ang Assoc.Prof. Giorgia Pastorin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(25):8321-8330
Human A3 adenosine receptor (hA3AR) is a membrane‐bound G protein‐coupled receptor implicated in a number of severe pathological conditions, including cancer, in which it acts as a potential therapeutic target. To derive structure–activity relationships on pyrazolo–triazolo–pyrimidine (PTP)‐based A3AR antagonists, we developed a new class of organometallic inhibitors through replacement of the triazolo moiety with an organoruthenium fragment. The objective was to introduce by design structural diversity into the PTP scaffold in order to tune their binding efficacy toward the target receptor. These novel organoruthenium antagonists displayed good aquatic stability and moderate binding affinity toward the hA3 receptor in the low micromolar range. The assembly of these complexes through a template‐driven approach with selective ligand replacement at the metal center to control their steric and receptor‐binding properties is discussed. 相似文献
120.
Michael P. Curtis William H. Bunnelle Thomas G. Pagano Murali Gopalakrishnan 《合成通讯》2013,43(3):321-326
Small heterocyclic amines such as 1,3‐diaza‐bicyclo[3.2.2]nonane are known to be key components of biologically active molecules. A convenient synthesis of this compound utilizing a key Beckmann rearrangement of (Z)‐1‐aza‐bicyclo[2.2.2]octan‐3‐one oxime (6) with conc. H2SO4 under microwave irradiation was achieved. The desired compound (1) was obtained in 20% yield overall. 相似文献