全文获取类型
收费全文 | 424篇 |
免费 | 30篇 |
国内免费 | 145篇 |
专业分类
化学 | 461篇 |
晶体学 | 27篇 |
力学 | 7篇 |
综合类 | 8篇 |
数学 | 2篇 |
物理学 | 94篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 20篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 16篇 |
2014年 | 18篇 |
2013年 | 50篇 |
2012年 | 19篇 |
2011年 | 22篇 |
2010年 | 15篇 |
2009年 | 26篇 |
2008年 | 16篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 26篇 |
2004年 | 32篇 |
2003年 | 36篇 |
2002年 | 42篇 |
2001年 | 38篇 |
2000年 | 36篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
排序方式: 共有599条查询结果,搜索用时 15 毫秒
141.
《Mendeleev Communications》2020,30(4):512-515
- Download : Download high-res image (217KB)
- Download : Download full-size image
142.
《Journal of Dispersion Science and Technology》2013,34(6):757-761
The bromocresol green pH indicator was encapsulated into transparent monolithic silica matrices using acid catalyzed sol‐gel reaction. Tetraethylorthosilicate was used for the entrapment of the bromocresol green indicator. The immobilized bromocresol green shows behavior similar to its solution counterpart. It retains its structure during the sol‐gel reactions in terms of response to pH and albumine. The polarized light microscopy has indicated that the bromocresol green molecules are strongly interacted within the host silica network. 相似文献
143.
Epitaixial metal‐oxide nanocomposite films, which possess interesting multifunctionality, have found applications in a wide range of devices. However, such films are typically produced by using high‐vacuum equipment, like pulse‐laser deposition, molecular‐beam epitaxy, and chemical vapor deposition. As an alternative approach, chemical solution methods are not only cost‐effective but also offer several advantages, including large surface coating, good control over stoichiometry, and the possible use of dopants. Therefore, in this Personal Account, we review the chemistry behind several of the main solution‐based approaches, that is, sol‐gel techniques, metal‐organic decomposition, chelation, polymer‐assisted deposition, and hydrothermal methods, including the seminal works that have been reported so far, to demonstrate the advantages and disadvantages of these different routes. 相似文献
144.
The stable alumina sol with an ASB/water molar ratio of 1:30 could not be obtained via the general peptization process because
gelation occurred immediately. With the addition of EAcAc the stability of this sol was greatly improved. The studies using
TEM, UV-V is and IR spectra revealed that a surface modification layer was formed around the Al2O3 colloidal particle through the chelating reaction of EAcAc with the surface HO-Al groups. The Al2O3 colloidal particles were therefore sufficiently capped and the growth of the colloidal particles was effectively prevented. 相似文献
145.
Dr. Veronika Kovacova Dr. Jung In Yang Leonard Jacques Dr. Song Won Ko Dr. Wanlin Zhu Prof. Susan Trolier-McKinstry 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9356-9364
(K0.5Na0.5)NbO3 (KNN) is a promising lead-free alternative for ferroelectric thin films such as Pb(Zr,Ti)O3. One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non-stoichiometry. This paper compares three acetate-based chemical solution synthesis and deposition methods for 0.5 mol % Mn-doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10−8 A cm−2 up to electric fields as high as 600 kV cm−1, which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two-step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed. 相似文献
146.
Elena Miloskovska Erik Nies Denka Hristova‐Bogaerds Martin van Duin Gijsbertus de With 《Journal of Polymer Science.Polymer Physics》2014,52(14):967-978
In situ silica was synthesized in three non‐vulcanized rubber matrices, namely natural rubber, styrene‐butadiene rubber, and EPDM (ethylene‐propylene diene ter‐polymer), using the sol–gel method with tetra‐ethoxysilane (TEOS) as silica precursor and hexylamine as catalyst. The effect of the reaction parameters such as the amount of TEOS, the reaction time (15–120 min), and the type of rubber was explored. Transmission electron microscopy was used to study the gradient in silica content and particle size over the sample thickness. The diffusion gradient of TEOS and catalyst solution in the rubber matrix responsible for the gradient was studied with Fick's law. An excellent dispersion of silica was obtained for all rubbers, even for the very non‐polar EPDM, without the use of any additives to improve the dispersion. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 967–978 相似文献
147.
采用超声膜扩散还原法制备出金属Pd纳米溶胶,然后从Pd纳米溶胶出发,采用不同方法制备出系列纳米Pd/Ce0.5Zr0.5O2催化剂。采用TEM观察Pd纳米粒子的形貌,采用N2吸/脱附,XRD,TPR和ICP对Pd/Ce0.5Zr0.5O2催化剂进行表征,并考察比较了各催化剂对CO+O2的催化活性差别,结果表明:先制备Pd纳米溶胶,再负载于载体上的方法制得的催化剂金属负载量较低,但是其活性最高,CO在150℃就能完全转化,金属分散度较高,活性Pd物种还原温度低,催化剂的CO低温活性与H2还原温度和金属分散度有关。这种催化剂制备方法为在提高催化剂活性的同时降低贵金属用量提供了可能。 相似文献
148.
T. Ivanova A. Harizanova T. Koutzarova B. Vertruyen 《Crystal Research and Technology》2010,45(11):1154-1160
Mixed ZnO‐ZrO2 films have been obtained by sol‐gel technology. By using spin coating method, the films were deposited on Si and glass substrates. The influence of thermal annealings (the temperatures vary from 400 °C to 750 °C) on their structural properties has been studied. The structural behavior has been investigated by the means of XRD and FTIR techniques. The results revealed no presence of mixed oxide phases, the detected crystal phases were related to the hexagonal ZnO and to crystalline ZrO2. The sol‐gel ZnO‐ZrO2 films showed polycrystalline structure with a certain degree of an amorphous fraction. The optical transmittance reached 91% and it diminished with increasing the annealing temperatures. The optical properties of the sol‐gel ZnO‐ZrO2 films, deposited on glass substrates are excellent with high transparency and better then those of pure ZrO2 films, obtained at similar technological conditions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
149.
150.
A new amperometric biosensor for hydrogen peroxide (H2O2) was developed by adsorbing hemoglobin (Hb) on an organic sol‐gel film. The organic sol‐gel was prepared using resorcinol and formaldehyde as monomers. This sol‐gel film shows a biocompatible microenvironment for retaining the native activity of the adsorbed Hb. The direct electron transfer between Hb and electrode is achieved. Hb adsorbed on the film shows an enzyme‐like catalytic activity for the reduction of H2O2. The reduction peak currents are proportional linearly to the concentration of hydrogen peroxide in the range of 6×10?8 to 3.6×10?6 M, with a detection limit of 2.4×10?8 M (S/N=3). This research enlarges the applications of organic sol‐gel materials in biosensor field. 相似文献