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971.
A new molecular magnet, [NO2BrBzPyCH3][Ni(mnt)2] ( 1 ) ([NO2BrBzPyCH3]+ = 1‐(2′‐bromo‐4′‐nitrobenzyl)‐2‐methylpyridinium, and mnt2– = maleonitriledithiolate), has been prepared and characterized by single crystal X‐ray diffraction and magnetic measurements. The Ni(III) ions of 1 form a quasi‐one‐dimensional alternating zig‐zag magnetic chain within a Ni(mnt)2– column by intermolecular Ni···S, Ni···Ni or π···π interactions, and the [NO2BrBzPyCH3]+ cations stack into a column via weak Br···O interaction, p···π stacking interactions and C‐H···O hydrogen bonds between the cations. Magnetic susceptibility measurements in the temperature range 1.8‐300 K show that 1 exhibits a spin‐gap transition around 180 K, and an antiferromagnetic interaction in the high‐temperature phase (HT) and spin gap behavior in the low‐temperature phase (LT). The transition for 1 is a second‐order phase transition as determined by DSC analyses. 相似文献
972.
Zheng ST Wu T Zuo F Chou C Feng P Bu X 《Journal of the American Chemical Society》2012,134(4):1934-1937
A new class of zeolite-type porous materials in which 3D frameworks are covalently functionalized with crystallographically ordered pendant metal clusters have been synthesized. This work demonstrates a new paradigm for and the feasibility of functionalizing zeolite-type frameworks through the conversion of extraframework sites in mineral zeolites into part of the framework for occupation by dangling metal clusters in metal-organic frameworks. 相似文献
973.
Ming-Hui Zuo Hui-Ling Liu Xu-Ri Huang Shu-Xin Cui 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(9):1438-1446
The reaction of N(4 S) radical with NO2 molecule has been studied theoretically using density functional theory and ab initio quantum chemistry method. Both singlet and triplet electronic state [N2O2] potential energy surfaces (PESs) are calculated at the G3B3 level of theory. Also, the highly cost-expensive coupled-cluster theory including single and double excitations and perturbative inclusion of triple excitations CCSD(T)/cc-pVTZ single-point energy calculation is performed on the basis of the geometries obtained at the Becke??s three parameter Lee-Yang-Parr B3LYP/6-311++G(d, p) level. On the singlet PES of the title reaction, it is shown that the most feasible pathway should be as follows. The atomic radical N attacking the NO bond of the NO2 molecule first to form the adduct 1 N(NO)O, followed by one of the NO bond broken to give intermediate 2 ONNO, and then to the major products P1 (2NO). On the triplet PES of the title reaction, it is shown that the most favorable pathway should be the atomic radical N attacking the N-atom of NO2 firstly to form the adduct 7 NN(OO), followed by one of the NO bonds breaking to give intermediate 8 NNOO, and then leading to the major products P2 (O2 + N2). As efficient routes to the reduction of NO2 to form N2 and O2 are sought, both kinetic and thermodynamic considerations support the viability of this channel. All the involved transition states for generation of (2NO), (3O + N2O), and (O2 + N2) lie much lower than the reactants. Thus, the novel reaction N + NO2 can proceed effectively even at low temperatures and it is expected to play a role in both combustion and interstellar processes. The other reaction pathways are less competitive due to thermodynamical or kinetic factors. On the basis of the analysis of the kinetics of all path-ways through which the reactions proceed, we expect that the competitive power of reaction pathways may vary with experimental conditions for the title reaction. The calculated reaction heats of formation are in good agreement with that obtained experimentally. 相似文献
974.
利用温和的方法进行了异戊烯基黄酮(±)-abyssinone-VI-4-O-methyl ether,(±)-abyssinone-IV-4’-O-methyl ether,(±)-abyssinone-V-4’-O-methyl ether和(±)-sigmoidin E的全合成研究,同时通过对羟基苯甲醛的异戊烯基化以及在石油醚中低温结晶的方法合成了关键中间体4-羟基-3,5-二异戊烯基苯甲醛.所有新化合物的结构都经过IR,1H NMR,MS,HRMS确认. 相似文献
975.
Zhuang Zuo Shen Tian Zebing Chen Jia Li Xiushan Yang 《Applied biochemistry and biotechnology》2012,167(7):2088-2102
The production of ethanol and methane from corn stover (CS) was investigated in a biorefinery process. Initially, a novel soaking pretreatment (NaOH and aqueous-ammonia) for CS was developed to remove lignin, swell the biomass, and improve enzymatic digestibility. Based on the sugar yield during enzymatic hydrolysis, the optimal pretreatment conditions were 1?% NaOH?+?8?% NH4OH, 50°C, 48?h, with a solid-to-liquid ratio 1:10. The results demonstrated that soaking pretreatment removed 63.6?% lignin while reserving most of the carbohydrates. After enzymatic hydrolysis, the yields of glucose and xylose were 78.5?% and 69.3?%, respectively. The simultaneous saccharification and fermentation of pretreated CS using Pichia stipitis resulted in an ethanol concentration of 36.1?g/L, corresponding only to 63.3?% of the theoretical maximum. In order to simplify the process and reduce the capital cost, the liquid fraction of the pretreatment was used to re-soak new CS. For methane production, the re-soaked CS and the residues of SSF were anaerobically digested for 120?days. Fifteen grams CS were converted to 1.9?g of ethanol and 1337.3?mL of methane in the entire process. 相似文献
976.
The adsorption and wrapping process of a single flexible comb-like polymer to a single wall nanotube was studied by Molecular
Dynamics simulation of a coarse-grained model. We varied the grafting density and length of the side chains, the radius of
the nanotube and strength of interaction between the monomers of nanotube and side chains of polymer brush. We investigated
the structural and dynamical characters of interactions of the nanotube-polymer composite, such as the effect of Lennard-Jones
energy parameter ɛLJ and the nanotube radius on the adsorption behavior and how the wrapping conformation is affected by the structure of the
polymer brush. The simulation results indicate that single comb-like polymer with flexible backbone tends to adsorb and wrap
around the nanotube, when the interaction energy exceeds a critical value. The monomer adsorption ratio, interaction energy
profiles and moment of inertia are obtained. The helical wrapping only occurs when the interaction energy is large enough.
Also, the influence of the polymer structure on the conformational behavior is analyzed. This work underscores design elements
important for engineering well-defined nanotube-polymer nanocomposite. 相似文献
977.
978.
Two superfluid states of nuclear matter, which are supposed to play an important role in neutron stars, are discussed: the first one due to the proton-proton 1 S 0 pairing in β-equilibrium nuclear matter; the second one due to the anisotropic neutron-neutron 3 PF 2 pairing in neutron matter. Since the two phases appear at high density of nuclear matter, the three-body forces were added to the pairing interaction and the strong correlation effects in the single-paricle spectrum. The energy gaps, obtained solving the extended BCS equations, significantly deviate from the values without medium effects so as to limit the role of these two superfluid states in the interpretation of phenomena occurring in the neutron-star core. 相似文献
979.
Following the approach of Carlet et al. (2011) [9], we construct a class of infinite-dimensional Frobenius manifolds underlying the Toda lattice hierarchy, which are defined on the space of pairs of meromorphic functions with possibly higher-order poles at the origin and at infinity. We also show a connection between these infinite-dimensional Frobenius manifolds and the finite-dimensional Frobenius manifolds on the orbit space of extended affine Weyl groups of type A defined by Dubrovin and Zhang. 相似文献
980.
We get a new inequality on the Hodge number $h^{1,1}(S)$ of fibred algebraic complex surfaces $S$ , which is a generalization of an inequality of Beauville. Our inequality implies the Arakelov type inequalities due to Arakelov, Faltings, Viehweg and Zuo, respectively. 相似文献