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191.
《Solid State Ionics》2009,180(40):1683-1689
The complex perovskite (Pr0.75Sr0.25)1 − xCr0.5Mn0.5O3 − δ (PSCM) has been prepared and studied as possible anode material for high-temperature solid oxide fuel cells (SOFCs). PSCM exhibits GdFeO3-type structure and is both physically and chemically compatible with the conventional YSZ electrolyte. The reduction of PSCM resulted in structural change from orthorhombic Pbnm to cubic Pm-3m. Selected area electron diffraction (SAED) analysis on the reduced phases indicated the presence of a √2 × √2 × 2 superlattice. The total conductivity values of ∼ 75% dense Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ at 900 °C in air and 5% H2/Ar are 9.6 and 0.14 S cm− 1 respectively. The conductivity of PSCM drops with decreasing Po2 and is a p-type conductor at all studied Po2. The average TEC of Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ is 9.3 × 10− 6 K− 1, in the temperature range of 100–900 °C and is close to that of YSZ electrolyte. The anode polarization resistance of PSCM in wet 5%H2 is 1.31 Ω cm2 at 910 °C and in wet CH4 at 930 °C; the polarization resistance is 1.29 Ω cm2. PSCM was unstable at 900 °C in unhumidified hydrogen. Cell performance measurements carried out using graded PSCM and La0.8Sr0.2MnO3 as anode and cathode respectively yielded a maximum power density of 0.18 W cm− 2 in wet 5%H2/Ar at 910 °C and the corresponding current density was 0.44 A cm− 2 at 0.4 V. The activation energy for the electrochemical cell operating in wet (3% H2O) 5%H2/Ar fuel is 85 kJ mol− 1. 相似文献
192.
使用Dy (NO3)3·6H2O与席夫碱配体2-(((2-羟基-3-甲氧基苄基)亚氨基)甲基)-4-甲氧基苯酚(H2L)和2个辅助配体PhCO2H和2-NO2-PhCO2H在乙醇中反应,得到2例Dy4配合物[Dy4(L)4(PhCO2)2(NO3)2(EtOH)2](1)和[Dy4(L)4(2-NO2-PhCO2)2(NO3)2(EtOH)2](2)。单晶X射线衍射解析表明配合物1和2均由Dy2基本单元构建,形成中心对称的四核线性链状结构。配合物1和2中Dy2单元中的一个Dy (Ⅲ)离子呈现七配位几何构型,另一个Dy (Ⅲ)离子呈现八配位几何构型。2例配合物均为单分子磁体,其能垒分别为110和108 K。通过理论计算对1和2的磁性能进行了分析。 相似文献
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195.
Gaopeng Liu Bin Wang Li Xu Penghui Ding Pengfei Zhang Jiexiang Xia Huaming Li Junchao Qian 《催化学报》2018,39(4):790-799
The oxygen reduction reaction (ORR) is a vitally important process in fuel cells. The development of high-performance and low-cost ORR electrocatalysts with outstanding stability is essential for the commercialization of the electrochemical energy technology. Herein, we report a facile synthesis of cobalt (Co) and nitrogen (N) co-doped carbon nanotube@porous carbon (Co/N/CNT@PC-800) electrocatalyst through a one-step pyrolysis of waste paper, dicyandiamide, and cobalt(II) acetylacetonate. The surface of the hierarchical porous carbon supported a large number of carbon nanotubes (CNTs), which were derived from dicyandiamide through the catalysis of Co. The addition of Co resulted in the formation of a hierarchical micro/mesoporous structure, which was beneficial for the exposure of active sites and rapid transportation of ORR-relevant species (O2, H+, OH?, and H2O). The doped N and Co formed more active sites to enhance the ORR activity of the electrocatalyst. The Co/N/CNT@PC-800 material exhibited optimal ORR performance with an onset potential of 0.005 V vs. Ag/AgCl and a half-wave potential of –0.173 V vs. Ag/AgCl. Meanwhile, the electrocatalyst showed an excellent methanol tolerance and a long-term operational durability than that of Pt/C, as well as a quasi-four-electron reaction pathway. The low-cost and simple synthesis approach makes the Co/N/CNT@PC-800 a prospective electrocatalyst for the ORR. Furthermore, this work provides an alternative approach for exploring the use of biomass-derived electrocatalysts for renewable energy applications. 相似文献
196.
受启发于近些年频繁曝出的消费者权益保护问题,为探析消费者行为对电商生态系统中其他群体策略选择的影响,本文基于演化博弈理论,考虑消费者的投诉行为,构建由政府、电商平台、商家以及消费者组成的四方演化博弈模型;讨论各方主体的策略选择,分析策略组合稳定点,并应用MATLAB工具进行仿真模拟实验。经上述研究,本文得出结论:消费者的投诉行为有利于促进政府严格监管、电商平台严格管理、商家诚信经营。由此,建议政府和电商平台充分发挥监督管理作用,以更好地保障消费者的合法权益,并遏制消费者的恶意投诉行为,从而实现电商生态系统的稳定可持续发展。 相似文献
197.
基于OH自由基的强氧化性(2.8 V)及脉冲放电等离子体(pulsed discharge plasma, PDP)与活性炭(activated carbon, AC)联合体系的协同作用,依托于光谱检测技术简单、准确性高、灵敏度高等优点,利用发射光谱技术测量了以O2作为载气的PDP/AC联合体系中产生的OH自由基的相对发射光谱,用以表征体系中OH自由基相对生成量的变化。通过考察PDP水处理体系中不同AC添加量、脉冲峰值电压、电极间距对OH自由基相对发射光谱强度的影响,分析了影响OH自由基生成量的因素;通过比较,分析去离子水和酸性橙II(acid orange, AO7)溶液中OH自由基发射光谱强度的变化规律,表征了OH自由基生成量的变化,以说明PDP/AC的协同作用机理及OH自由基对有机物的氧化作用。研究结果表明,增加AC的添加量可以增强其在PDP体系中的催化效果,导致PDP/AC联合体系中OH自由基的相对发射光谱强度的增加;随着脉冲峰值电压的升高,注入PDP体系中的能量增加,从而增加了体系中OH自由基的产量;电极间距增加导致PDP体系能量效率降低,降低了OH自由基的产生量;无论是以去离子水还是以AO7溶液为溶液相,PDP/AC联合体系中OH自由基的产量均高于其在单独PDP体系中的生成量,且在PDP/AC联合体系和单独的PDP作用体系中,去离子水中OH自由基的相对发射光谱强度均高于其在AO7溶液中的强度值,这证明了AC对PDP体系中OH自由基生成的协同作用和有机物对OH自由基的消耗。 相似文献
198.
《Physica B: Condensed Matter》2005,355(1-4):9-13
The metastable Nd(Al) supersaturated solid solution with the BCC structure was synthesized by the melt-spinning method. The thermal stability of the supersaturated solid solution was studied by differential scanning calorimetry (DSC) and electrical-resistance measurements. The structural modification was determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). A constrained BCC lattice was found due to the smaller Al atoms entering the BCC-Nd lattice. Two evident transformation stages were found during the heating process. The lower activation energy and negative temperature coefficient of the resistivity (TCR) suggest that a continuous structural transformation occur, which results from the softening mode of the highly metastable BCC structure. The strongly distorted and ultra-fine microstructure was observed directly by TEM. 相似文献
199.
以共沉淀法制备出Fe3O4纳米粒子,通过聚乙烯亚胺(PEI)修饰Fe3O4纳米粒子,再原位复合上Au纳米粒子,制得Fe3O4/PEI/Au纳米颗粒微球。再将Fe3O4/PEI/Au纳米颗粒与巯基乙酸修饰的量子点CdSe/CdS连接,成功制备了Fe3O4/PEI/Au@CdSe/CdS多功能复合微球。经过傅里叶变换红外光谱仪(FTIR)、荧光分光光度计、荧光显微镜、X射线衍射(XRD)、透射电子显微镜(TEM)及振动样品磁强计(VSM)的表征。结果表明:多功能复合微球的粒径在40nm左右,具有超顺磁性,剩磁,矫顽力近似等于零,饱和磁化强度为28.83A·m2·kg-1,同时兼有优越的荧光性能和金纳米粒子的特性。 相似文献
200.
Dawei Li Yafei Li David Felipe Tello Yepes Xiamei Zhang Prof. Dr. Yahong Li Prof. Dr. Jin-lei Yao 《化学:亚洲杂志》2021,16(17):2545-2551
A hexanuclear heterometallic cluster of composition [Dy2Co4(L)4(NO3)2(OH)4(C2H5OH)2] ⋅ 2 C2H5OH ( 1 ) was synthesized by employing a Schiff base 2-(((2-hydroxy-3-methoxybenzyl) imino)methyl)-4-methoxyphenol (H2L) as ligand and utilizing Dy(NO3)3 ⋅ 6H2O and Co(NO3)2 ⋅ 6H2O as metal ion sources. X-ray single-crystal diffraction analysis indicated that complex 1 contains a defect tetracubane core and possesses central symmetric structure, with two DyIII ions being in the central body position of the molecule and four CoII ions being arranged at the outer sites. Magnetic studies reveal that complex 1 behaves as single-molecule magnet (SMM) with energy barrier of 27.50 K. To investigate the individual contribution of DyIII and CoII ions to the SMM behavior, another two complexes of formulae [Dy2Zn4(L)4(NO3)2(OH)4] ⋅ 4CH3OH ( 2 ) and [Y2Co4(L)4(NO3)2(OH)4(C2H5OH)2] ⋅ 2 C2H5OH ( 3 ) were prepared. Complexes 1 and 3 are isomorphous. The coordination geometries of DyIII ions in 1 and 2 are different. The DyIII ions are eight-coordinated in 2 and nine-coordinated in 1 . Complex 2 exhibits SMM behavior with energy barrier of 69.67 K, but complex 3 does not display SMM property. These results reveal that the SMM behaviors of 1 and 2 are mainly originated from DyIII ions. It might be the higher symmetry of DyIII ions in 2 that results in the higher energy barrier. 相似文献