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1.
We describe the ultrasonic assisted preparation of barium stannate-graphitic carbon nitride nanocomposite (BSO-gCN) by a simple method and its application in electrochemical detection of 4-nitrophenol via electro-oxidation. A bath type ultrasonic cleaner with ultrasonic power and ultrasonic frequency of 100 W and 50 Hz, respectively, was used for the synthesis of BSO-gCN nanocomposite material. The prepared BSO-gCN nanocomposite was characterized by employing several spectroscopic and microscopic techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, fourier transform infra-red, field emission scanning electron microscopy, and high resolution transmission electron microscopy, to unravel the structural and electronic features of the prepared nanocomposite. The BSO-gCN was drop-casted on a pre-treated glassy carbon electrode (GCE), and their sensor electrode was utilized for electrochemical sensing of 4-nitrophenol (4-NP). The BSO-gCN modified GCE exhibited better electrochemical sensing behavior than the bare GCE and other investigated electrodes. The electroanalytical parameters such as charge transfer coefficient (α = 0.5), the rate constant for electron transfer (ks = 1.16 s−1) and number of electron transferred were calculated. Linear sweep voltammetry (LSV) exhibited increase in peak current linearly with 4-NP concentration in the range between 1.6 and 50 μM. The lowest detection limit (LoD) was calculated to be 1 μM and sensitivity of 0.81 μA μM−1 cm−2. A 100-fold excess of various ions, such as Ca2+, Na+, K+, Cl−, I−, CO32−, NO3, NH4+ and SO42− did not able to interfere with the determination of 4-NP and high sensitivity for detecting 4-NP in real samples was achieved. This newly developed BSO-gCN could be a potential candidate for electrochemical sensor applications. 相似文献
2.
A simple and sensitive voltammetric sensor for esculetin, based on electrochemically reduced graphene oxide film modified glassy carbon electrode, was reported for the quantitative determination of esculetin in the Chinese traditional herbal drug Viola yedoensis Makino. Electrochemical impedance spectroscopy and scanning electron microscopy were employed to study the characteristic of the graphene oxide film. The electrochemical behavior of esculetin on this sensor was investigated in pH 3.0 phosphate buffer solution by cyclic voltammetry. Significant advantages were achieved by the excellent conductivity and the high surface‐to‐volume ratio of electrochemically reduced graphene oxide. A calibration plot of oxidation peak currents versus esculetin concentrations was linear in the range of 4.0 ξ 10‐8 mol L‐1 to 5.0 ξ 10‐6 mol L‐1 with a detection limit of 2.0 ξ 10‐8 mol L‐1. The practical application of the present sensor was demonstrated by determining the concentration of esculetin in real sample with no interference. 相似文献
3.
The time-dependent motion in the lubricating layer of a gas bearing is analyzed on the basis of the compressible boundary layer equations with allowance for the inertial effects and the transverse temperature drop. After introducing certain assumptions concerning the order of the main dimensionless parameters, approximate expressions for the velocity and temperature are derived. As a result, the problem reduces to the determination of the pressure as a function of the space coordinate and time. 相似文献
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5.
In this paper, we establish a mathematical model of online game addiction with two stages to research the dynamic properties of it. The existence of all equilibria is obtained, and the basic reproduction number is calculated by the method of next-generation matrix. The global asymptotic stability of disease-free equilibrium (DFE) is proved by comparison principle, and the global asymptotic stability of endemic equilibrium (EE) is proved by constructing an appropriate Lyapunov function. Then we use the Pontryagin's maximum principle to find the optimal solution of the model, so that the number of infected people can be minimized. In numerical simulation, firstly, we validate the global stability of DFE and EE. Secondly, we consider three kind of control measures (treatment, isolation, and education) and divide them into four cases. The models with control and without control are solved numerically by using forward and backward sweep Runge-Kutta method. In order to achieve the best control effect, we suggest that three kind of measures should be used simultaneously according to the optimal control strategy. 相似文献
6.
《Analytical letters》2012,45(12):1031-1040
Abstract Linear sweep voltammetry at glassy carbon or other carbon materials is shown to be a simple, highly sensitive, and relatively versatile analytical method for the determination of thiourea and thiourea dioxide. Using the first one-electron oxidation peak occurring at ~0.6V, thiourea can be determined directly in a variety of electrolytes from concentrated acids to solutions of pH ~5. The thiourea dioxide determination is based on the two-electron oxidation peak which appears in a number of electrolytes at ~1.2V. 相似文献
7.
增殖剂球床是聚变堆或混合堆产氚包层可选结构之一,准确把握增殖剂球床中载带气体的流动特性有助于提高对球床载氚过程的认识并优化包层设计。采用离散元程序PFC3D模拟增殖剂小球的填充行为,在球床内不同位置随机截取不同尺寸的控制体,利用布尔运算中的"差集"得到孔隙范围,建立孔隙分布的三维几何模型,进一步划分网格并用计算流体力学(CFD)方法求解,得出控制体上单位长度的压降以及单元体内的速度分布特征,计算结果发现载带气体速度分布与γ分布很类似,且只要选取恰当的控制体,通过计算流体力学方法可以较好地分析整个球床孔隙内流体的流动,有利于进一步研究载氚及相关过程。 相似文献
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9.
Libuse Trnkova Ladislav Novotny Nuria Serrano Katerina Klosova Petra Polaskova 《Electroanalysis》2010,22(16):1873-1880
Elimination voltammetry with linear scan (EVLS) in connection with renewed mini‐ drop mercury electrodes provides valuable information about the character and kinetics of processes at electrode/electrolyte interfaces. Based on the experiment related to the hydrogen evolution, it is presented that the EVLS is more sensitive than other voltammetric methods. Using miniaturized mercury electrodes, the EVLS is capable of detecting the effect of spherical diffusion associated with both the scan rates and the size of an electrode drop. 相似文献
10.
飞行器变后掠过程非定常气动特性形成机理 总被引:2,自引:0,他引:2
可变体飞行器变后掠过程中的时变气动力与力矩特性对于飞行安全具有重要意义,是亟待深入研究的基础问题.通过风洞实验对其开展了研究,揭示了可变体飞行器变后掠引起的气动特性动态迟滞现象及滞回环大小与方向的影响因素.基于风洞实验结果和力学中一些重要概念,提出了3种物理效应:流场迟滞效应、附加运动效应、固壁牵连效应,以此定性与定量论证了可变体飞行器变后掠过程中非定常气动特性的形成机理.除了能解释实验现象,这一机理研究亦可用于后续可变体飞行器变后掠过程中的气动特性建模. 相似文献