全文获取类型
收费全文 | 106篇 |
免费 | 5篇 |
国内免费 | 19篇 |
专业分类
化学 | 80篇 |
晶体学 | 1篇 |
力学 | 19篇 |
数学 | 5篇 |
物理学 | 25篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有130条查询结果,搜索用时 15 毫秒
121.
122.
The aim of this work was to study the growth characteristics of micro-plasma oxidation ceramic coatings on Ti-6Al-4V alloy. Compound ceramic coatings were prepared on Ti-6Al-4V alloy by pulsed micro-plasma oxidation (MPO) in NaAlO2 solution. The phase composition and surface morphology of the coating were investigated by X-ray diffractometry and scanning electron microscopy. The solution of Ti from the substrate and the content of Al in the electrolyte were studied by inductively coupled plasma-atomic emission spectrometer (ICP-AES) technique. Ti from the substrate dissolved and came into the coating and the electrolyte during MPO process. The content of Ti in the electrolyte under the pulsed bi-polar mode was more than that of the pulsed single-polar mode. The phase composition and structure of the coating was attributable to the space steric hindrance of Al congregated on the electrode surface due to the effect of the electric field and the electrolyte characters. For the pulsed single-polar mode, the coating was mainly composed of a large amount of α-Al2O3 and a small amount of γ-Al2O3. And the coating was mainly structured by Al from the electrolyte. However, the coating was composed of a large amount of Al2TiO5 and a little α-Al2O3 and rutile TiO2 for the pulsed bi-polar mode. And the coating was structured both by Ti from the substrate and Al from the electrolyte. 相似文献
123.
Huan Tian Sicheng Huang Peng Bai Xiao Xiao Duo Peng Huan Zhao Yuqing Liu Qian Feng Miao Liao Fuping Li Weibo Liang 《Electrophoresis》2021,42(16):1614-1622
In the past decade, mRNA markers have been well demonstrated as promising molecular markers in forensic body fluid identification (BFI), and successfully used in wide applications. Several studies have assessed the performance of semen-specific mRNA markers in distinguishing semen from other common body fluids at the crime scene. Infertility has been reported as a global health problem that is affecting approximately 15% of couples worldwide. Therefore, it is important for forensic researchers to consider the impact of infertility on semen identification. This study aimed to explore the effect of semen from infertile men (hereinafter “infertile semen”) on BFI and to identify semen-specific mRNAs that can efficiently and accurately distinguish normal and infertile semen samples from other body fluids. Results showed that the selected five mRNAs (KLK3, TGM4, SEMG1, PRM1, and PRM2) performed a significantly high semen specificity in normal semen. Moreover, KLK3 was slightly influenced by infertile semen samples with over 98% positive results in all semen samples. The accuracy to predict normal semen reached up to 96.6% using the discrimination function Y1 with KLK3 and PRM1. However, when the infertile semen samples were included in discrimination function (function Y2 with KLK3), the accuracy rate of semen identification (including the normal and infertile semen) was down to 89.5%. Besides, the sensitivity of multiplex assay could reach down to 50pg. Our results suggest that it is important to consider the presence of infertile semen when using mRNAs to identify semen samples, which would have a far-reaching impact in forensic identification. 相似文献
124.
Dong T Ma H Zhang W Gong L Wang F Li C 《Journal of colloid and interface science》2007,311(2):523-529
Inorganic-organic composite films containing the mixed-addenda heteropolytungsto-molybdate K(10)H(3)[Eu(SiMo(9)W(2)O(39))(2)]xH(2)O (abbreviated as EuSiMo(9)W(2)) and tris(2,2'-bipyridine)ruthenium(II) Ru(bpy)(2+)(3) (abbreviated as Ru(bpy)(3)) were fabricated by the layer-by-layer self-assembly method. UV-vis spectroscopy shows that the absorbance values at characteristic peaks increase linearly with the number of EuSiMo(9)W(2)/Ru(bpy)(3) bilayers, suggesting that the deposition process is linear and highly reproducible from layer to layer. The composition of the multilayer film was measured by X-ray photoelectron spectra. Atomic force microscopy presented a correspondingly uniform surface morphology and a homogeneity of the multilayer films. The film exhibited photoluminescence arising from the d-pi* metal-to-ligand transition of Ru(2+), and (5)D(0) metastable state to terminate levels in the (7)F(J) (J=0-4) ground-state multiplet transitions of Eu(3+). The film also exhibited catalytic activities toward the reduction of IO(-)(3), H(2)O(2), BrO(-)(3), NO(-)(2) and the oxidation of C(2)O(2-)(4). It may provide a novel material as bifunctional electrocatalysts and fluorescence probes in biochemistry, luminescence sensors, electroluminescent optical devices, and so on. 相似文献
125.
126.
IC Determination of Halide Impurities in Ionic Liquids 总被引:1,自引:0,他引:1
An ion chromatographic (IC) method has been developed for determination of trace levels of halide impurities in various types
of ionic liquids (ILs). The advantage of this method is that all relevant halide species can be measured in a single chromatographic
analysis. Separation of halides was performed on a Dionex AS9-HC column using an eluent consisting of 20 mM NaOH and 10% (v/v) acetonitrile, delivered at 1.5 mL min−1. Using this eluent, fluoride, chloride and bromide were well resolved from each other, but iodide was co-eluted with tetrafluoroborate
(BF4−) present as a counter-anion in tetrafluoroborate-based ILs. The same eluent was also used successfully for the determination
of halides in highly hydrophobic ILs, such as those based on bis-(trifluoromethanesulfonyl)imide (TFSI−) and bis-perfluoroethylsulfonylimide (BETI−). In this case, 50% (v/v) acetonitrile aqueous was needed to dissolve the sample before injection, and this did not adversely affect the separation.
Detection limits in the measured solution were 0.1, 0.2 and 1.0 ppm for chloride, bromide and iodide, respectively, by conductivity
detection, and 0.02 ppm for iodide by UV detection. 相似文献
127.
128.
129.
在一种名为Chaparral的野生灌木生长的环境中,经常发生危害极大的野火。本文建立了一个马尔可夫链模型,可以对Chaparral的土地管理和火灾控制策略的优劣进行评估。同时本模型还被用于决定一个最优限制燃烧策略。 相似文献
130.