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81.
Jihui Li Huiqing Shi Ning Li Mei Li Jing Li 《Central European Journal of Chemistry》2010,8(4):783-788
Graphite intercalation compounds are often prepared by flake graphite, oxidants, inorganic acids, organic acids and intercalated
ions which are usually hydrogen protons between the graphene planes. They are also known as the acid-treated graphite intercalation
compounds. In this work, alkaline graphite intercalation compounds were prepared by flake graphite, K2Cr2O7, concentrated H2SO4 and NaOH, and the morphology and structure were characterized by Electron microscopy and X-ray techniques. The results display
that the combination of neutralisation heat and oxidation capability produced by K2Cr2O7 can break the bonds to produce the spaces between the graphene planes and hydroxyl ions also intercalate into the graphene
planes to form alkaline graphite intercalation compounds in alkali solution. The morphology and structure of alkaline graphite
intercalation compounds are analogous to the ones of the acid-treated graphite intercalation compounds, but the intercalated
ions and the expansion volume are different. The results show that the method is an innovation. 相似文献
82.
83.
§1. IntroductionLetΩbeaboundedsmoothdomainintheHeisenberggroupHn,weareconcernedwiththeproblemofsemilinearsubellipticLaplaceequation-ΔHnu=up+f(x,u),inΩ,u>0, inΩ,(1.1)u=0, onΩ,wherepisarealnumber,f(x,y)satisfiessuitableassumptions(seebelowsectio… 相似文献
84.
85.
In this paper we prove the existence of multi-bump solutions for a class of quasilinear Schrödinger equations of the form \({-\Delta{u} + (\lambda{V} (x) + Z(x))u - \Delta(u^{2})u = \beta{h}(u) + u^{22*-1}}\) in the whole space, where h is a continuous function, \({V, Z : \mathbb{R}^{N} \rightarrow \mathbb{R}}\) are continuous functions. We assume that V(x) is nonnegative and has a potential well \({\Omega : = {\rm int} V^{-1}(0)}\) consisting of k components \({\Omega_{1}, \ldots , \Omega{k}}\) such that the interior of Ω i is not empty and \({\partial\Omega_{i}}\) is smooth. By using a change of variables, the quasilinear equations are reduced to a semilinear one, whose associated functionals are well defined in the usual Sobolev space and satisfy the geometric conditions of the mountain pass theorem for suitable assumptions. We show that for any given non-empty subset. \({\Gamma \subset \{1, \ldots ,k\}}\), a bump solution is trapped in a neighborhood of \({\cup_{{j}\in\Gamma}\Omega_{j}}\) for\({\lambda > 0}\) large enough. 相似文献
86.
Applying activated carbons for SO2 adsorption and conversion to H2SO4, as a dry process, has been considered the development direction of desulfurization technology. Coal-based activated carbon, coconut shell activated carbon, single wall carbon nanotube and multi-wall carbon nanotubes were used as typical carbonaceous materials to study the SO2 adsorption mechanism. SEM, N2 adsorption, XPS and fixed-bed reaction system were employed to study the morphology, pore structure, surface functional groups and SO2 adsorption behaviors of the four adsorbents. The fixed-bed experiment was carried out at normal pressure and SO2 concentration was set 1,000 ppm. According to SEM and N2 adsorption results, hierarchical pore structure was an important characteristic of activated carbon. Aggregation was an important characteristic of CNTs. Mesopores and macropores took the dominance of pore structure in CNTs. According the SO2 adsorption data and correlation analysis, it can be concluded that the dominant adsorption type on activated carbons does not alter with adsorption temperature changing. However, the adsorption type of SO2 adsorption on CNTs changes with adsorption temperature varying. With adsorption temperature increasing, the dominant adsorption type transforms to chemisorption by physisorption. Higher-density π–π* in carbon nanotubes may be the active sites for the SO2 chemical adsorption. Micropores with the diameter smaller than 0.7 nm were the best SO2 adsorption place for both activated carbons and carbon nanotubes. The results provided a profound insight into the microstructure and SO2 adsorption mechanism of the two kinds of carbonaceous materials. 相似文献
87.
Jinguo Long Rongrong Yu Jihui Gao Xianjie Fang 《Angewandte Chemie (International ed. in English)》2020,59(17):6785-6789
Enantioselective auto‐tandem catalysis represents a challenging yet highlight attractive topic in the field of asymmetric catalysis. In this context, we describe a dual catalytic cycle that merges allylic cyanation and asymmetric hydrocyanation. The one‐pot conversion of a broad array of allylic alcohols into their corresponding 1,3‐dinitriles proceeds in good yield with high enantioselectivity. The products are densely functionalized and can be easily transformed to chiral diamines, dinitriles, diesters, and piperidines. Mechanistic studies clearly support a novel sequential cyanation/hydrocyanation pathway. 相似文献
88.
Hu Jia Jihui Ni Wanfen Pu Ping Yue Hang Jiang Jianjun Yang 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1707-1714
In the previous study, the oxidation behavior of four Chinese crude oils (Oil 1 to 4) in the presence and absence of rock cuttings was investigated by thermogravimetry/derivative thermogravimetry (TG/DTG) techniques and oxidation tube experiments. The present work investigates the thermal behavior of these oils by combining DTG–DTA method. First, we conducted comparative analysis about mass loss rate from DTG curves and endothermic/exothermic phenomenon from DTA curves attempting to clarify the endothermic or exothermic mechanism in crude oil low-temperature oxidation. Finally, we combined the thermal analysis method with low-temperature oil oxidation tube experiment in porous media to ascertain, whether the two methods are consistent in the aspect of low-temperature oxidation mechanism of crude oil by O2 consumption rate and CO2 generating rate (carbon bond stripping reaction rate). Results show that crude oils undergo an endothermic oxidation behavior during low-temperature oxidation stage, suggesting the decomposition of hydrocarbon components. Clay can play a catalytic effect on low-temperature oil oxidation. The results of DTG–DTA tests can also better reflect oil oxidation mechanism under real conditions. 相似文献
89.
Ni/La_2O_3/Al_2O_3催化剂上甲烷干重整积炭表征与分析(英文) 总被引:3,自引:0,他引:3
用传统的等体积浸渍法或蒸发法制备了Ni/La_2O_3/γ-Al_2O_3与Ni/La_2O_3/α-Al_2O_3催化剂,在没有稀释气体的条件下进行了甲烷干重整反应.采用H_2程序升温还原、N_2吸附脱附、X射线衍射、透射电子显微镜、热重-差示扫描热量以及程序升温加氢等手段对新鲜的与反应后的催化剂以及沉积的碳进行了表征.结果表明,催化剂上有四种含碳物种,以三种形态存在,即无定形碳(聚合态)、丝状碳或石墨碳.这些催化剂上积炭的数量与种类各不相同,依赖于催化剂中金属Ni颗粒的大小与载体的织构特性.丝状碳的形成及其形貌与金属Ni颗粒的大小有着密切的联系.Ni颗粒小于15nm时能抑制丝状碳的形成与沉积.减少积炭的数量,同时能产生较多的活性C_a物种,从而在一定程度上导致催化剂具有较好的活性与稳定性. 相似文献
90.
Some existence theorems are obtained for periodic solutions of a class of non-autonomous second order Hamiltonian systems with local superquadratic potential, by making use of the generalized mountain pass theorem. 相似文献