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121.
二甲四氯钠(MCPA-Na)是一种广泛用于牧场和果园的除草剂,但由于其生物降解性极低,已成为地下水和浅水中的主要污染物.研究发现,半导体可以有效地辅助降解转化危险化学品.ZnO纳米管因其中空结构和较大的比表面积,而在光催化降解有机物方面备受关注.但是,ZnO只能吸收紫外光,如果将其与窄带隙半导体进行复合,可以有效降低带隙,增强其在可见光区域的光吸收,表现出更好的光催化性能.WO3是一种具有稳定物理化学性质及耐光腐蚀窄带隙半导体.采用WO3修饰ZnO纳米管,能扩展ZnO吸收光的范围以及提高ZnO纳米管的耐光腐蚀性能.本文首先通过电化学合成的方法制备了ZnO纳米管,然后按照不同的W/Zn摩尔比将(NH4)6H2W12O40·XH2O滴加在纳米管表面,并在450 ℃下退火2 h制得ZnO-WO3纳米管阵列.研究了不同WO3含量的ZnO-WO3纳米管光催化降解MCPA-Na性能,并且通过X射线光电子能谱(XPS)、傅里叶红外光谱仪(FTIR)、紫外可见光谱(UV-Vis)和光致发光光谱(PL)等手段研究了复合WO3纳米颗粒后ZnO纳米管半导体光催化性能提高的原因.XPS结果表明,W元素在ZnO-WO3纳米管阵列中以W6+的形式存在.FTIR结果表明,复合WO3后的ZnO-WO3复合半导体上比纯ZnO纳米管表面具有更多的OH-基团.由于OH-可以捕获光生空穴,并转化为具有反应活性的●OH自由基,因此复合WO3能在一定程度上提高ZnO纳米管的光催化活性.UV-Vis结果表明,WO3的复合使得光谱发生明显红移,但随着WO3含量的增加,ZnO-WO3的吸光度明显增加.另外,PL结果表明,适当的复合WO3可以抑制光生电子-空穴的复合.这是因为W6+和晶格氧的相互作用产生了较高不饱和键和表面缺陷,而表面缺陷可以作为光生载流子的陷阱,促进了光生电子和空穴的分离,因而光催化性能提高.在模拟太阳光下研究了不同WO3含量的ZnO纳米管对光催化降解MCPA-Na溶液的性能.发现W/Zn摩尔比为3%的ZnO-WO3样品表现出最好的光催化活性,200 min内其降解率为98.5%.与纯ZnO纳米管相比,其光催化循环性能也有所提高.利用Mott-Schottky测试方法并结合UV-vis结果,我们计算得到不同WO3含量的ZnO-WO3复合半导体导带价带位置.由于WO3导带位置和价带位置都比ZnO的更高,WO3上产生的光生电子会向ZnO的导带移动,而ZnO光生空穴向WO3的价带移动,从而促使光生电子和空穴的分离,提高了光催化性能.但是如果WO3复合的量太大,则在ZnO纳米管上分散性不好,反而成为光生空穴和电子复合中心,导致其光催化活性降低. 相似文献
122.
Temperature stability of symmetric activated carbon (AC) supercapacitors (SCs) assembled with in situ electrodeposited poly(vinyl alcohol) potassium borate hydrogel electrolyte was systematically studied and compared with that of AC SCs assembled with liquid aqueous electrolytes in the temperature range from -5℃ to 80℃. 相似文献
123.
KunWei Li XiaoTian Meng Xue Liang Hao Wang Hui Yan 《Journal of Solid State Electrochemistry》2006,10(1):48-53
Electrodeposition of lead selenide (PbSe) thin films on indium tin oxide (ITO) covered glass is described. While disodium salt of ethylenediaminetetraaceticacid was used to complex the lead ions, well crystallized, nearly stoichiometric and mirror-like PbSe films were deposited on ITO glass in potentiostatic mode using aqueous acidic electrolyte containing Pb and Se precursors at different bath temperature. The improvement of crystallinity of the PbSe films deposited at different temperature was studied using X-ray diffraction and Raman scattering. The morphology and composition of the films were characterized by scanning electron microscopy and energy disperse analysis by X-ray, respectively. The optical property of the film was studied by optical measurement techniques. 相似文献
124.
F.?Huet M.?MusianiEmail author R.?P.?Nogueira 《Journal of Solid State Electrochemistry》2004,8(10):786-793
Rough and porous Ni layers have been obtained by cathodic deposition from a NiCl2, NH4Cl solution, at high current density. Characterisation by SEM has shown that they consisted of micro-dendrites separated by pores with a typical diameter of 1 m. In addition, circular hollows (10–100 m in diameter) were found on the deposit surface; their density varied with the deposition current density and deposition charge. The surface roughness of the Ni deposits, measured by EIS, was found to increase roughly linearly with the deposition charge, and to be little dependent on current density, provided a threshold value was exceeded. The oxygen evolution reaction has been studied on these electrodes by simultaneous real-time measurements of potential and electrolyte resistance fluctuations. The analysis of the electrochemical noise indicated that the dimensions of oxygen bubbles detaching from the electrodes slightly increased with the deposit surface roughness. It is not clear, however, whether or not this increase was associated with the effect of the small (1 m) or the large (10–100 m) features on the electrode-bubble interactions. 相似文献
125.
126.
电化学法制备生物活性陶瓷材料研究 总被引:6,自引:0,他引:6
利用电化学方法可以在温和条件下制备生物活性陶瓷涂覆层,从而避免了高温喷涂引起的相变和脆裂,并可在形状复杂的基底上得到均匀的沉积层.因此,近年来在金属表面电沉积生物活性陶瓷涂覆层的研究方面已引起高度重视[’-‘j,然而,目前大多数文献报道所采用的恒电位方法,在沉积过程中电极表面的喊度会发生较大的变化,难以得到组分均匀的沉积层.本文报道用恒电流模式在Ti-6A14V合金表面沉积羟基磷灰石生物陶瓷涂层.1实验部分Ti-6A14V合金为电沉积基底(直径为0.65cm),辅助电极为Pt电极,参比电极采用饱和甘汞电极(SCE).… 相似文献
127.
This article deals with a linear stability analysis of electrodeposition. The surface energy is disregarded in order to focus on the possible effects of the finite width of the electric double layer and the finite electrode reaction rate upon the wavelength selection. It is found that in the absence of electroconvection the fastest growing perturbation mode is that with a wavelength equal to the geometric average of the Debye length and the reaction diffusion length, which is the ratio of diffusivity to the electrode reaction rate. This wavelength is one–two orders of magnitude greater than that selected by the capillarity mechanism based on the surface energy estimates. This shift of the selected wavelength towards long waves is enhanced by another order of magnitude by electroconvection in the regime of the nonequilibrium electroosmosis developing upon the emergence of the extended space charge. 相似文献
128.
129.
Xin Huang Kang Zhi Bin Mai Xiao Yong Zou Pei Xiang Cai Jin Yuan Mo School of Chemistry Chemical Engineering Sun Yat-Sen University Guangzhou China College of Science Guangdong Ocean University Zhanjiang China 《中国化学快报》2007,18(2):189-191
Cu nanoclusters were electrochemically deposited on the film of a Nafion-solubilized multi-wall carbon nanotubes (CNTs) modified glassy carbon electrode (CNTs-GCE), which fabricated a Cu-CNTs composite sensor (Cu-CNTs-GCE) to detect glucose with non-enzyme. The linear range is 7.0×10-7 to 3.5×10-3 mol/L with a high sensitivity of 17.76μA/(mmol L), with a low detection limit 2.1×10-7 mol/L, fast response time (within 5 s), good reproducibility and stability. 相似文献
130.
A. Mourato S. M. Wong H. Siegenthaler L. M. Abrantes 《Journal of Solid State Electrochemistry》2006,10(3):140-147
The deposition of palladium as microparticles on electrogenerated polyaniline (PAni) films accomplished by metal electroless
precipitation or by electrodeposition has been used to prepare stable polymer-modified electrode systems. Its general morphology,
metal particles size and distribution were obtained by AFM analysis. The PAni/Pd microparticles electrodes have been evaluated
for their catalytic activity towards hydrogenation reactions upon organic compounds reduction using 4-nitro-benzaldehyde.
Studies on rotating ring-disk electrodes have shown that relatively low Pd loadings are required to obtain effective electrocatalytic
activity, provided a good metal particles dispersion of about 100 nm diameter is observed.
Dedicated to Professor M. A. Vorotyntsev on the occasion of his 60th birthday 相似文献