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101.
A direct synthetic route for the C―S coupling of aryl halides with thiophenols is described. This method is tolerant to electron‐withdrawing and electron‐donating functional groups and also to the presence of functional groups in the ortho position of the aryl iodide or thiophenol. Aryl iodides are coupled with thiophenols without affecting the other functionalities present in the aryl ring. These reactions follow second‐order kinetics. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
102.
Nonlinear Dynamics - This paper investigates bursting dynamics of a Rayleigh oscillator with multiple-frequency slow excitations, in which two different bursting patterns related to the bistable... 相似文献
103.
Transport of salt through the wall of porous microtube is relevant in various physiological microcirculation systems. Transport phenomena based modeling of such system is undertaken in the present study considering a combined driving force consisting of pressure gradient and external electric field. Transport of salt is modeled in two domains, in the flow conduit and in the pores of porous wall of the microtube. The solute transport in the microtube is presented by convective‐diffusive mass balance and it is solved using integral method under the framework of boundary layer analysis. The wall of the microtube is considered to be consisting of series of straight parallel cylindrical pores with charged inner surface. The solute transport through the pores is considered to be composed of diffusive, convective and electric potential gradient governed by Nernst‐Planck equation. Transport in the microtube and pores is coupled through the osmotic pressure model for the solvent and Donnan equilibrium distribution for the solute. The simulated results agree remarkably well with the experimental data conducted by in‐house experimental set up. The charge density of the porous wall is estimated through the minimization of errors involved between the experimental and simulated data for different operating conditions. 相似文献
104.
Madhulika Pathak Shaibal Gupta Debashis Bhattacharya M. K. Rao B. K. Bhaumik 《Indian Journal of Physics》2009,83(7):993-1000
Indigenously fabricated portable gamma-ray spectrometer (PGRS) is used for the measurement of gamma activity of 214Bi (1.76 MeV) and 208TI (2.62 MeV), under field conditions in Mohar area, Shivpuri Distt. (MP). The energies are discriminated by using a Nal (TI)
crystal of size 1.75″ × 2″. PGRS used to map the primordial elemental distributions shows reversals of concentration of thorium
and uranium (represented by radium group) in field and lab analysis in many samples, which is attributed to the inhomogenity
of distribution of these elements in the area. The concept of difference in the volume of dish shaped field sample and the
randomly picked up sample from the field grid point (400 gm in lab analysis) is utilized to interpret the inhomogenity of
these elements. However interpretations are based on the assumption that these primordial elements (U, Th) are in secular
equilibrium and the terrain has low topographic relief.
相似文献
105.
Debashis Chanda Ladan E. Abolghasemi Peter R. Herman 《Applied Physics A: Materials Science & Processing》2008,93(1):33-37
Phase tunable multi-level diffractive optical elements define an attractive approach for single laser exposure fabrication
of 3-dimensional photonic crystal microstructures. The significant advantage of these multi-level diffractive optical elements
over two-level diffractive optical elements is the flexibility of fabricating a wide range of 3-dimensional periodic structures
by manipulating the relative phase of different diffracted beams. Here, phase tuning was applied to demonstrate fabrication
of a hybrid 3-dimensional structure intermediate between previously reported diamond-like Woodpile-type structure of tetragonal
symmetry and structure having body-centered-tetragonal lattice symmetry. Circularly polarized light was applied for the first
time to balance the diffraction order efficiencies and improve the structural uniformity. Design guidelines are presented
for generating diamond-like photonic crystal template that possesses complete photonic bandgap when inverted with high refractive
index materials. 相似文献
106.
Conventional glycoconjugate vaccines are prepared with polysaccharides isolated from bacterial fermentation, an approach with some significant drawbacks such as handling of live bacterial strains, the presence of biological impurities, and inter‐batch variations in oligosaccharide epitope structure. However, it has been shown in many cases that a synthetic fragment of appropriate structure conjugated to a protein can be an effective vaccine that circumvents the shortcomings of using full‐length oligosaccharides. The development of synthetic strategies to prepare glycoconjugate derivatives against pathogenic bacterial strains is therefore of great interest. Oligosaccharide fragments corresponding to the repeat unit of the cell wall O‐antigen of Salmonella enterica strain O53 were synthesized in good yield. Sequential and block glycosylation strategies were used for the synthesis of the target compounds. A number of recently developed reaction conditions were used in the synthetic strategy. A one‐pot reaction scheme was also developed for the multiple glycosylation steps. The stereoselective outcomes of all glycosylation reactions were very good. 相似文献
107.
Ligand Transformations and Efficient Proton/Water Reduction with Cobalt Catalysts Based on Pentadentate Pyridine‐Rich Environments 下载免费PDF全文
Debashis Basu Dr. Shivnath Mazumder Xuetao Shi Habib Baydoun Dr. Jens Niklas Dr. Oleg Poluektov Prof. H. Bernhard Schlegel Prof. Cláudio N. Verani 《Angewandte Chemie (International ed. in English)》2015,54(7):2105-2110
A series of cobalt complexes with pentadentate pyridine‐rich ligands is studied. An initial CoII amine complex 1 is prone to aerial oxidation yielding a CoIII imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N‐methyl protecting group to the ligand inhibits this oxidation and gives rise to the CoII species 5 . Both the CoIII 4 and CoII 5 show electrocatalytic H2 generation in weakly acidic media as well as in water. Mechanisms of catalysis seem to involve the protonation of a CoII? H species generated in situ. 相似文献
108.
Seiichiro Ten-no Suehiro Iwata Sourav Pal Debashis Mukherjee 《Theoretical chemistry accounts》1999,102(1-6):252-261
Employing separate cluster ansatz in time-independent and time-dependent wave-operators, coupled-cluster (CC) response theory
is generalized to multireference (MR) expansion spaces. For state energies, this corresponds to the MR secular problem with
an arbitrary similarity-transformed effective Hamiltonian, H˜=Ω−1
HΩ. The effective Hamiltonian can be generated via size-extensive CC methods. Thus the states in MR linear response theory
(MRLRT) maintain the usual CC core-extensive properties. We have used the Gelfand unitary group basis of the spin-adapted
configurations to construct the matrix of H˜ in the MR excitation space. As a preliminary application, the CC singles and
doubles effective Hamiltonian is applied to excitation and photoionization energies of the CH+ and N2 molecules, and is compared with experimental results and results from other numerical procedures including conventional CC
linear response theory (CC-LRT), MR and full configuration interaction (MRCI and FCI) methods. The numerical results indicate
that MRLRT reproduces valence and external excited states quantitatively, combining the best features of CC-LRT and MRCI.
Received: 2 July 1998 / Accepted: 28 August 1998 / Published online: 11 November 1998 相似文献
109.
Debasis Jana Barun Bandyopadhyay Debashis Mukherjee 《Theoretical chemistry accounts》1999,102(1-6):317-327
We present in this paper a multi-reference coupled cluster (MRCC) formulation for energy differences which treats orbital
relaxation and correlation effects on the same footing, by invoking a novel cluster ansatz of the valence portion of the wave
operator Ωv. Unlike in the traditional normal-ordered exponential representation of Ωv, our new relaxation-inducing ansatz, represented symbolically as E
r(S), allows contractions between the spectator lines and also certain other special contractions. By an extensive theoretical
analysis, taking as an example the case of one-hole model space (the IP problem), we demonstrate that our ansatz incorporates
in a manifestly spin-free form the orbital relaxation to all orders. The traditional Thouless-type of exponential transformation
via one-body excitations can induce the same effect, as is done in the valence-specific or the quasi-valence-specific MRCC
formalisms, but they have to be done in the spin-orbital basis – making the spin adaptation of the problem a complicated exercise.
In contrast, we use a spin-free representation of the cluster operators right from start, but expand the rank of the cluster
operators by involving spectator orbitals to distinguish the various spin possibilities. The combinatorial factors entering
the contracted power series in E
r(S) are chosen in such a way that they correspond to what we would have obtained if we had used a Thouless-like transformation
to induce the orbital relaxation. Our working equations generally have only finite powers of the cluster operators S, resulting in a very compact formulation of the relaxation problem. Pilot numerical applications for the IP computations
of HF and H2O in the core, the inner valence and the outer valence regions show very good performance of the method vis-a-vis those obtained
using the traditional normal ordered ansatz for Ωv. The improvement in the core IP value is particularly impressive, although even for the valence regions there is an overall
improvement of the IP values.
Received: 3 August 1998 / Accepted: 30 September 1998 / Published online: 15 February 1999 相似文献
110.
Transition Metal Chemistry - After the publication of this article ‘Bis-chelates of nickel(II) and copper(II) with an O,S-donor piperazine ligand,’ it came to our attention that... 相似文献