全文获取类型
收费全文 | 160篇 |
免费 | 2篇 |
国内免费 | 57篇 |
专业分类
化学 | 158篇 |
晶体学 | 4篇 |
力学 | 4篇 |
物理学 | 53篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 16篇 |
2012年 | 7篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 19篇 |
2008年 | 18篇 |
2007年 | 17篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 2篇 |
排序方式: 共有219条查询结果,搜索用时 15 毫秒
31.
Carboxyl group-functionalized single-walled carbon nanotubes (SWNTs) and 2,6-pyridinedicarboxylic acid (PDC) were electropolymerized
by cyclic voltammetry on a glassy-carbon electrode (GCE) surface to form composite films (SWNTs/PDC). Zirconia was then electrodeposited
on the SWNTs/PDC/GCE from an aqueous electrolyte containing ZrOCl2 and KCl by cycling the potential between −1.1 V and +0.7 V at a scan rate of 20 mV s−1. DNA probes with a phosphate group at the 5′ end were easily immobilized on the zirconia thin films, because of the strong
affinity between zirconia and phosphate groups. The sensors were characterized by cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). EIS was used for label-free detection of the target DNA by measuring the increase of the electron
transfer resistance (R
et) of the electrode surface after the hybridization of the probe DNA with the target DNA. The PAT gene fragment and polymerase
chain reaction (PCR) amplification of the NOS gene from transgenically modified beans were satisfactorily detected by use
of this DNA electrochemical sensor. The dynamic range of detection of the sensor for the PAT gene fragment was from 1.0 × 10−11 to 1.0 × 10−6 mol L−1 and the detection limit was 1.38 × 10−12 mol L−1. 相似文献
32.
33.
利用X射线光电子能谱、紫外光电子能谱和低能电子衍射研究了Ni纳米颗粒在ZrO2(111)薄膜表面的生长模式、电子结构及热稳定性. ZrO2(111)薄膜外延生长于Pt(111)单晶表面,厚度约为3 nm.结果表明,当Ni气相沉积到ZrO2(111)薄膜表面上时,遵循Stranski-Krastanov生长模式,即先二维生长至0.5 ML(monolayer),然后呈三维岛状生长.随着覆盖度的减小, Ni 2p3/2峰逐渐向高结合能位移.利用俄歇参数法分析发现,引起该峰向高结合能位移的主要原因来源于终态效应的贡献,但在低的Ni覆盖度时,也有部分初态效应的贡献,说明Ni在ZrO2表面初始生长时,两者存在较强的界面相互作用, Ni向ZrO2衬底传递电荷,形成带部分正电荷的Niδ+.两种不同覆盖度(0.05和0.5 ML)的Ni/ZrO2(111)模型催化剂热稳定性研究表明,当温度升高时, Ni逐渐被氧化成Ni2+,并伴随着向ZrO2衬底的扩散.本文从原子水平上认识了Ni与ZrO2表面的相互作用和界面结构,为理解实际ZrO2担载的Ni催化剂结构提供了重要的依据. 相似文献
34.
Al2O3-ZrO2 composite coatings were deposited by the suspension plasma spray process using molecularly mixed amorphous powders. X-ray diffraction (XRD) analysis shows that the as-sprayed coating is composed of α-Al2O3 and tetragonal ZrO2 phases with grain sizes of 26 nm and 18 nm, respectively. The as-sprayed coating has 93% density with a hardness of 9.9 GPa. Heat treatment of the as-sprayed coating reveals that the Al2O3 and ZrO2 phases are homogeneously distributed in the composite coating. 相似文献
35.
共掺杂的二氧化锆纳米材料中Yb3+和Tm3+上转换发光 总被引:4,自引:0,他引:4
用共沉淀法制备了二氧化锆掺Yb3 和 0 2 (0 4 ,1)mol%Tm3 的纳米材料 ;用发射波长为 980nm的激光激发样品 ,测量了掺 0 2mol%Tm3 的纳米材料在不同退火温度下的上转换光谱 ;测量了在相同退火温度、不同泵浦电流下的上转换发射光谱 ;并研究了蓝色上转换发射的过程。 相似文献
36.
G. V. Krylova Yu. I. Gnatyuk N. P. Smirnova A. M. Eremenko V. M. Gun’ko 《Journal of Sol-Gel Science and Technology》2009,50(2):216-228
A variety of Ag nanoparticles/oxide mesoporous films with templated silica, titania, and zirconia was synthesized by sol–gel
method at glass, aluminum, and silicon substrates using metal alkoxides (tetraethoxysilane, titanium tetraisopropoxide, and
zirconium tetrapropoxide) and AgNO3 as precursors of oxide films and Ag nanoparticles, respectively, and Pluronic P123 as a template agent. Oxide films alone
and Ag/oxide composites were characterized using hexane adsorption, X-ray diffraction (XRD), Raman and ultraviolet (UV)/vis
spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The distribution of
Ag nanoparticles within the films, their sizes, intensity, and position of surface plasmon resonance (SPR) absorbance band
at λ = 400 nm, as well as the textural and structural characteristics of whole films depend on treatment temperature, types of
substrates and oxide matrices, oxide crystallization, and Ag content. Ag nanoparticles form preferably on the outer surface
of the films under lower sintering temperatures if the amount of loaded silver is low. Oxide crystallization (e.g., TiO2) promotes silver embedding into the outer film layer. At higher silver content (≥10 at.%) and higher calcination temperature
(873 K), silver nanoparticles could be entrapped more uniformly along the film profile because of more intensive evaporation
of silver droplets from the outer surface of the films on heating. 相似文献
37.
Catalytic dehydration of 2‐propanol and that of 1‐butanol were performed at atmospheric pressure and 150–300°C over ZrO2 and sulfated ZrO2 (S/ZrO2) in a fixed‐bed, tubular reactor. The catalysts were characterized with XRD, elemental analysis, FT‐IR, N2 physisorption, TG/DTA, TPD, and TPR. The main structures of ZrO2 and S/ZrO2 were monoclinic and tetragonal, respectively. As ZrO2 was modified with sulfuric acid, its surface area and acid amount were greatly increased, whereas the pore volume, the pore diameter, and the particle size were reduced. Both samples owned weak basicity. For both reactions, only dehydration products of alkene and ether were obtained. The alcohol conversion enhanced remarkably with the catalyst acid amount and the surface area as well as the reaction temperature. In addition, the ether selectivity on S/ZrO2 decreased with raising the reaction temperature. The activation energy was 81.0 kJ/mol in the propene formation from 2‐propanol over S/ZrO2. The corresponding value was 94.4 kJ/mol for the dehydration of 1‐butanol. 相似文献
38.
The conductivity behavior of nitrogen-doped zirconia is compared with that of zirconia doped with lower-valent cations and discussed in the framework of defect-defect interactions. While nominally introducing the same number of vacancies as yttrium, nitrogen dopants introduced in the anion sublattice of zirconia lead to substantially different defect kinetics and energetics. Compared to the equivalent yttrium doping nitrogen doping in the Y-Zr-O-N system substantially increases the activation energy and correspondingly decreases the conductivity at temperatures below in the vacancy range below 4 mol%. The comparison of N-doped zirconia and zirconia systems doped with size-matched cation stabilizers, such as Sc, Yb and Y, shows that elastically driven vacancy-vacancy ordering interactions can phenomenologically account for the temperature- and composition-dependence. It is striking that materials with superior high-temperature conductivities due to weak dopant-vacancy interactions undergo severe deterioration at low temperature due to the strong vacancy-ordering. The analysis also explains qualitatively similar effects of Y co-doping in Yb-, Sc-, and N-doped zirconia. Small amount of Y in N-doped zirconia as well as in Sc-doped zirconia appears to hinder the formation of the long-range ordered phase and thus enhance the conductivity substantially. 相似文献
39.
A simple method to synthesize tetragonal zirconia stabilized at ambient temperature is developed and allows the monitoring of the tetragonal-monoclinic transition via a colloidal sol-gel process. By increasing the pH of an aqueous solution consisted of a zirconium precursor and a complexing agent (acetylacetone), a colloidal sol and then a gel can be formed under slightly acidic condition. After a drying step, tetragonal zirconia is easily obtained with an adequate thermal treatment at low temperature. The tetragonal-monoclinic transition occurs when the calcination temperature is increased. The relationship between the crystallite size, the crystallographic structure and the thermal treatment has been investigated by X-Ray Diffraction and the behaviour of the system from the gel state to the final powder has been studied by using Small Angle X-Ray Scattering and thermal analysis techniques. We demonstrate that compared to a chemical precipitation route, this colloidal sol-gel process allows the nanostructure of the material to be controlled due to the formation of primary nanoparticles. The presence of these nanoparticles makes possible the specific determination of the zirconia crystallographic phase through an accurate control of the nanostructure during the thermal treatment. 相似文献
40.
《Journal of Coordination Chemistry》2012,65(14):2234-2245
Zr(OPri)4·PriOH reacts with N-phenylsalicylideneimine in anhydrous benzene in 1 : 2 molar ratio to afford [Zr{O(C6H4)CH=NPh}2{OPri}2] (1). Further reactions of 1 with various glycols yield heteroleptic complexes of the type [Zr{O(C6H4)CH=NPh}2{O–G–O}] [where–G–= (CH2)2 (2), (CH2CHCH3) (3), (CH3CHCHCH3) (4), (CH2CHC2H5) (5), (CH2)3 (6), (CH2CH2CHCH3) (7), and (CH2)6 (8)]. All new derivatives have been characterized by elemental analyses, FTIR and NMR (1H and 13C{1H}) studies. FAB mass spectra of 1 and 7 revealed the monomeric nature of these complexes. Complete hydrolyses and low temperature transformations of 1 and 7 using Sol-Gel technique formed tetragonal phase of ZrO2 at 700°C, whereas transformation of tetragonal to monoclinic phase occurred at 900°C. SEM observations of these samples indicate formation of agglomerates of nanocrystalline zirconia (Scherer analysis). 相似文献