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排序方式: 共有182条查询结果,搜索用时 15 毫秒
1.
Chao Duan Jianwei Zhang Shali Cai Junjun Xiang Prof. Xiaodi Yang Prof. Xike Gao 《European journal of organic chemistry》2023,26(5):e202201347
Linear polycyclic systems are promising candidates in the area of organic electronics. Herein, we present the syntheses of three azulene-indole (AzIn) fused polycyclic heteroaromatics (PHAs), AzIn - 1 , AzIn - 2 and DGAzIn , which have nitrogens and nonhexagonal rings simultaneously. The chemical structures, optical and electrochemical properties of three AzIn-based PHAs have been investigated, as well as their protonation behaviors with trifluoroacetic acid (TFA). All three AzIn-based PHAs exhibit narrow optical band gaps with moderate to good air stability, anti-Kasha emission and reversible stimuli-responsiveness. Furthermore, these straightforward and simple synthetic routes would provide a new entry for constructing novel azulene-embedded π-conjugates, especially for the seven-membered ring of azulene unit, wherein the regioselective transformation is not well developed. 相似文献
2.
为了消除非线性因素对相位生成载波解调结果的干扰,降低相位生成载波解调过程中低通滤波器的频响特性对相位生成载波解调结果的影响,该文提出了一种基于扩展卡尔曼滤波椭圆参数估计的相位生成载波微分交叉相乘解调方法。该方法在综合考虑各种非线性因素对相位生成载波微分交叉相乘解调结果的影响的基础上,对传统的相位生成载波微分交叉相乘解调过程进行了改进。经过计算机仿真和实验验证,该文所提出的扩展卡尔曼滤波微分交叉相乘方法能够有效地抑制非线性因素对相位生成载波解调结果的干扰,相比传统的相位生成载波微分交叉相乘方法,其信噪比提高了35.0 d B,总谐波失真降低了30.7 dB,信噪谐波比提高了31.0 dB,且扩展卡尔曼滤波微分交叉相乘方法受解调过程中低通滤波器频响特性的影响较小。 相似文献
3.
本工作设计合成了分别含有B—N键和C=C键的薁基[4]螺烯类分子1a/1b和2, 其中B—N键和C=C键互为等电子体. 紫外-可见吸收光谱、电化学循环伏安测试和理论计算结果表明B—N键可以调控共轭骨架的电子结构及芳香性. 单晶结构表明1a具有螺旋几何构型, 晶体中存在P和M两种对映异构体. B—N键具有部分双键性质, 硼氮六元环具有一定的芳香性. 大位阻基团2,4,6-三甲基苯基(Mes)使得1b在三氟乙酸(TFA)作用下不会发生类似于1a的脱硼化, 而是发生和2相似的可逆质子响应, B—N键对薁单元的质子响应性质无明显影响. 三配位的硼原子可以进一步和氟离子配位, 使得1a对氟离子有明显的选择性响应, 而1b则因大位阻的Mes取代基的存在对氟离子无明显的响应性. 本工作报道了新型薁基硼氮杂螺烯及全碳螺烯分子, 为薁基多环芳烃的“自下而上”合成及性质研究提供了参考. 相似文献
4.
Excitable media,such as cells,can be polarized and magnetized in the presence of an external electromagnetic field.In fact,distinct geometric deformation can be induced by the external electromagnetic field,and also the capacitance of the membrane of cell can be changed to pump the field energy.Furthermore,the distribution of ion concentration inside and outside the cell can also be greatly adjusted.Based on the theory of bio-electromagnetism,the distribution of field energy and intracellular and extracellular ion concentrations in a single shell cell can be estimated in the case with or without external electric field.Also,the dependence of shape of cell on the applied electronic field is calculated.From the viewpoint of physics,the involvement of external electric field will change the gradient distribution of field energy blocked by the membrane.And the intracellular and extracellular ion concentration show a certain difference in generating timevarying membrane potential in the presence of electric field.When a constant electric field is applied to the cell,distinct geometric deformation is induced,and the cell triggers a transition from prolate to spherical and then to oblate ellipsoid shape.It is found that the critical frequency in the applied electric field for triggering the distinct transition from prolate to oblate ellipsoid shape obtains smaller value when larger dielectric constant of the cell membrane and intracellular medium,and smaller conductivity for the intracellular medium are used.Furthermore,the effect of cell deformation is estimated by analyzing the capacitance per unit area,the density of field energy,and the change of ion concentration on one side of cell membrane.The intensity of external applied electric field is further increased to detect the change of ion concentration.And the biophysical effect in the cell is discussed.So the deformation effect of cells in electric field should be considered when regulating and preventing harm to normal neural activities occurs in a nervous system. 相似文献
5.
6.
Xiaodi Li T. Caraballo R. Rakkiyappan Xiuping Han 《Mathematical Methods in the Applied Sciences》2015,38(14):3130-3140
In this paper, the stability problem of impulsive functional differential equations with infinite delays is considered. By using Lyapunov functions and the Razumikhin technique, some new theorems on the uniform stability and uniform asymptotic stability are obtained. The obtained results are milder and more general than several recent works. Two examples are given to demonstrate the advantages of the results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
Xiaodi Wang Ying Ma Abhilash Sugunan Jian Qin Muhammet S. Toprak Bin Zhu Mamoun Muhammed 《Journal of nanoparticle research》2011,13(11):5879-5885
A facile surfactant-free nonaqueous method is presented to prepare uniform quasi-octahedral ceria, CeO2, mesocrystals, in which only Ce(NO3)3 and octanol were used as the reactants at a reaction temperature of 150 °C. CeO2 sample synthesized using this technique consists of well-dispersed quasi-octahedrons and exhibits an uniform size and morphology.
Based on structural characterization, it is proposed that the CeO2 mesostructure was formed by self-assembly of primary nanocrystals based on unique 3D oriented-attachment mechanism. Optical
characterization exhibited a strong quantum confinement, revealing small size of primary nanocrystals. The thermal stability
and UV–Vis study reveal CeO2 mesocrystal has various potential for high temperature applications and optical apparatus applications. 相似文献
8.
光谱法研究有机农药污染物与DNA的相互作用 总被引:1,自引:0,他引:1
利用紫外光谱、荧光光谱及圆二色谱(CD)等光谱方法研究了有机农药敌敌畏(DDVP)、乐果(DIM)、氧化乐果(OME)及生物农药申嗪霉素的有效成分吩嗪-1-羧酸(PCA)与端粒脱氧核糖核酸(DNA)间的相互作用。 结果表明,有机农药分子可能主要以嵌入模式与DNA结合,DDVP、DIM、OME以及PCA与端粒DNA之间的表观结合常数分别为:1.17×106、1.48×106、4.52×105和1.80×106 L/mol,与DNA结合能力的大小顺序为PCA>DIM>DDVP>OME。 这些有机农药分子明显不利于DNA双螺旋结构的稳定性。 有机农药分子的嵌入削弱了DNA碱基对之间的π-π堆积作用,对DNA的二级结构有一定的影响,使得DNA的双螺旋结构变得松散。 相似文献
9.
A procedure was developed for the determination of residual monomers in polycarboxylate superplasticizer by reversed-phase high performance liquid chromatography. Seven kinds of residual monomers were quantitatively determined on a SinoChrom ODS-BP (C18) column and UV detector at 205 nm. The mobile phases which were used to determine micromolecular monomers were composed of acetonitrile and phosphate buffer solution (0.05 mol L?1, pH = 3) in the ratio of 8:92 (v/v). While the mobile phases for long side-chain monomers testing were composed of acetonitrile and phosphate buffer solution (0.05 mol L?1, pH = 6.5) in the ratio of 40:60 (v/v). The linear response ranged from 4.0 × 10?6?C2.0 × 10?3 mol L?1. The detection limit was 0.12 × 10?5?C0.8 × 10?5 mol L?1. Determination of real samples showed that relative standard deviation of high conversion rate samples was 3.1?C8.7% and standard addition recovery ratio was 91.5?C102.8%. While the relative standard deviation of low conversion rate samples was less than or close to 1% and the standard addition recovery ratio was 96.3?C103.1%. 相似文献
10.