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141.
Samia Yahyaoui Rached Ben Hassen Bruno Donnadieu Jean‐Claude Daran Abdelhamid Ben Salah 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):i109-i111
The title compound, namely octaaquaytterbium(III) aquanonachlorotricadmate(II) hexahydrate, [Yb(H2O)8][Cd3Cl9(H2O)]·6H2O, was prepared by evaporation at 278 K from an aqueous solution of the ternary system YbCl3–CdCl2–H2O and was characterized by elemental chemical analysis and by X‐ray powder and single‐crystal diffraction studies. The crystal structure can be viewed as being built from layers of double chains of CdCl6 and CdCl5(H2O) octahedra separated by antiprismatic [Yb(H2O)8]3+ cations. The stabilization of the structure is ensured by O—H⋯O and O—H⋯Cl hydrogen bonds. A comparison with the structures of SrCd2Cl6·8H2O and CeCd4Cl11·13H2O is presented. 相似文献
142.
In this paper we prove an existence result for the nonlinear elliptic problem:-△u = Ku~5,u 0 in Ω,u = 0 on?Ω,where Ω is a smooth bounded domain of R~3 and K is a positive function in Ω.Our method relies on studying its corresponding subcritical approximation problem and then using a topological argument. 相似文献
143.
案例重用是使用旧的经验去解决新的问题,可以提升基于案例推理的故障诊断系统解决问题的能力,本文提出一种基于知识约简的故障案例重用方法,主要包括针对静态案例的值约简算法(improved attribute value reduction algorithm based on discernibility matrix,IAVRADM)以及新增案例情况下的值约简增量式更新算法(incremental updating algorithm for attribute value reduction,IUAAVR),其中,IAVRADM算法利用吸收律和互信息增量作为启发式信息,改进了已有算法中分辨矩阵构造和搜索过程,提高了决策规则的生成效率,IUAAVR算法分析总结出需要进行规则更新的3种情况.实验结果表明,IAVRADM算法的适应性强、时间开销低,IUAAVR算法在获得相同数量的决策规则情况下与案例的数量无关且更具时间优势. 相似文献
144.
BEN G. FITZPATRICK 《Natural Resource Modeling》2005,18(3):261-279
ABSTRACT. In this paper, we examine models for exploration and consumption of resources. The fundamental feature of the models is the jump‐process nature of the exploration for and discovery of the resource. Several models have been proposed and analyzed in the literature. Here we provide numerical schemes, convergence properties, and some new models that provide risk‐averse policies to avoid depletion of the resource. 相似文献
145.
Hassen Aydi 《Journal de Mathématiques Pures et Appliquées》2008,89(1):49-69
For disc domains and for periodic models, we construct solutions of the Ginzburg–Landau equations which verify in the limit of a large Ginzburg–Landau parameter specified qualitative properties: the limit density of the vortices concentrates on lines. 相似文献
146.
Hassen Khazri Ibtissem Ghorbel‐Abid Sihem Ben Hassine Sylvie Chevolleau Laurent Debrauwer Rafik Kalfat Malika Trabelsi‐Ayadi 《Journal of separation science》2019,42(9):1710-1716
In this work, clay‐Na particles are used as the adsorbent for the solid‐phase extraction of acidic compounds. The novel sorbent under study is based on high‐specific surface area, cation‐exchange capacity designed specifically to offer ion‐exchange properties with the goal being to selectively extract a group of acidic compounds. The effects of the extraction parameters including extraction elution solvent, sample volume and pH. In optimum conditions, the repeatability for one fiber (n = 3), expressed as % relative standard deviation, was between 0.3 and 4.3% for the acid compounds. The detection limits for the studied acidic compounds were between 0.1–0.6 μg/L. The developed method offers the advantages of being simple to use and having a low cost of equipment. 相似文献
147.
Laroussi Chaabane Hassiba Chahdoura Wassim Moslah Mejdi Snoussi Emmanuel Beyou Mohammed Lahcini Najet Srairi‐Abid Mohamed Hassen V. Baouab 《应用有机金属化学》2019,33(5)
This work describes a simple synthesis of complexes of the type [M(C32H28N4)Cl2], where M = Ni (II), Cu (II) and Fe (II) and a novel complex of magnetite nanoparticle (Fe3O4NP) inside (INS) tetraaza macrocyclic Schiff base ligand (C32H28N4): [Fe3O4NP‐INS‐(C32H28N4)], which was prepared by using a novel co‐precipitation method of coordinated ferric ion (Fe3+) in the complex [Fe(C32H28N4)Cl2] under mild conditions. The synthesized compounds were characterized and compared with a various physic‐chemical techniques like: Fourier transform infrared (FT‐IR), ultraviolet–visible spectroscopic techniques (UV–Vis), 1‐dimensional (1D) 1H‐NMR, 13C‐NMR spectroscopic techniques, mass spectra, Powder X‐ray diffraction (PXRD), Vibrating sample magnetometer (VSM), Scanning electron microscopy (SEM), elemental analysis and molar conductance measurements. Furthermore, the highest saturation magnetization was 26.56 emu.g?1 obtained from [Fe3O4NP‐INS‐(C32H28N4)] (diameter of Fe3O4NPs~20.87 nm) that prove easy separation by an external magnetic field. In vitro screening of all the compounds against different species of bacteria and fungi shows that [Fe3O4NP‐INS‐(C32H28N4)] is effective against the tested strains as compared to the tetraaza macrocyclic ligand and selected complexes. The cytotoxic activity of the all compounds was also examined in 3 human tumor cell lines as U87, MDA‐MB‐231 and LS‐174. The complex [Fe3O4NP‐INS‐(C32H28N4)] shows moderate and strong cytotoxic activity against brain cancer, colon cancer and breast cancer (U87, MDA‐MB‐231 and LS‐174 respectively), without showing cytotoxicity towards peripheral blood mononucleocyte (PBMC) cells. 相似文献
148.
一代材料,一代电池。锂离子电池正极材料的研究不断推动着动力电池的升级换代。第一代动力电池的正极材料为锰酸锂LiMn2O4,其低温性能好、成本低和安全性高,但电池能量密度不够高。第二代动力电池正极材料为磷酸铁锂LiFePO4和三元正极材料镍钴锰NCM/镍钴铝NCA。磷酸铁锂正极材料的优势是长寿命、低成本、高安全性。三元锂正极材料的特点是大容量、高能量密度、快充效率高。第三代动力电池的正极材料是高电压镍锰酸锂LiNi0.5Mn1.5O4和镍酸锂LiNiO2,主要解决第二代面临的低成本和长续航不能兼顾的问题以及更长里程问题。文章首先回顾第一、二代的锰酸锂、磷酸铁锂和三元正极材料的研究历程、优缺点及发展近况,之后介绍和展望下一代高电压镍锰酸锂和镍酸锂正极材料。 相似文献
149.
用溶剂诱导的含联萘基团的手性聚芳醚酮类环状齐聚物(S-PENEKC)制备修饰电极,利用循环伏安法实现了对D,L,DL-色氨酸/磷钨杂多酸的超分子化合物(D,L,DL—H,Trp2-[PW12O40])的手性识别. 相似文献
150.
为解决可再生能源存在的间歇性和波动性等问题,考虑到现有大规模储能技术的不足,提出了一种兼具抽水蓄能技术和压缩空气储能技术特点的恒压型抽水压缩空气储能系统.首先建立其热力学模型和经济学模型,然后以能量效率和单位能量成本作为目标函数,以水气比、预置压力、增压机压比和增压机效率作为决策变量,分别针对容量为1 MW、2MW、5 MW的系统进行多目标优化。多目标优化结果表明,当水气比约为7、预置压力约为4 MPa、增压机压比约为2、增压机效率较高时,系统具有较高的能量效率和较低的单位能量成本。同时,随着系统容量的增加,单位能量成本明显降低。研究结果可为该系统的工程应用提供理论支撑。 相似文献