首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   25篇
  免费   0篇
化学   10篇
数学   1篇
物理学   14篇
  2013年   2篇
  2011年   1篇
  2008年   1篇
  2006年   2篇
  2005年   2篇
  2004年   2篇
  2001年   1篇
  2000年   2篇
  1998年   1篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1981年   1篇
  1976年   1篇
排序方式: 共有25条查询结果,搜索用时 15 毫秒
1.
2.
3.
This study outlines the use of mid-infrared (MIR) spectroscopy combined with principal component analysis (PCA) and linear discriminant analysis (LDA) for the varietal classification of commercial red and white table wines. Three red varieties (Cabernet Sauvignon, Shiraz and Merlot) and four white varieties (Chardonnay, Riesling, Sauvignon Blanc and Viognier) were sourced from different wine regions in Australia. Wine samples were scanned in transmission on a FOSS WineScan FT 120 from wave numbers 926 to 5012 cm−1. All samples were sourced from the 2006 vintage and had not been blended with any other variety or wine from other regions. Spectral data were reduced to a small number of principal components (PCs) and LDA was then performed to successfully separate the wines into the different varieties. To test the robustness of the LDA models developed for the red wines, a set of red wines scanned in 2005 were used. Correct classification of over 95% was achieved for the validation set.  相似文献   
4.
The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed.  相似文献   
5.
6.
7.
This report describes affinity measurements for two, water-soluble, methyl-alkylated diamides incorporating the malonamide functionality, N,N,N',N' tetramethylmalonamide (TMMA) and a bicyclic diamide (1a), toward actinide metal cations (An) in acidic nitrate solutions. Ligand complexation to actinides possessing oxidation states ranging from +3 to +6 was monitored through optical absorbance spectroscopy, and formation constants were obtained from the refinement of the spectrophotometric titration data sets. Species analysis gives evidence for the formation of 1, 4, 1, and 2 spectrophotometrically observable complexes by TMMA to An(III, IV, V, and VI), respectively, while for 1a, the respective numbers are 3, 4, 2, and 2. Consistent with the preorganization of 1a toward actinide binding, a significant difference is found in the magnitudes of their respective formation constants at each complexation step. It has been found that the binding affinity for TMMA follows the well-established order An(V) < An(III) < An(VI) < An(IV). However, with 1a, Np(V) forms stronger complexes than Am(III). The complexation of 1a with Np(V) and Pu(VI) at an acidity of 1.0 M is followed by reduction to Np(IV) and Pu(IV), whereas TMMA does not perturb the initial oxidation state for these dioxocations. These measurements of diamide binding affinity mark the first time single-component optical absorbance spectra have been reported for a span of actinide-diamide complexes covering all common oxidation states in aqueous solution.  相似文献   
8.
The total synthesis of heliannuol C and E from a common intermediate are described. Key steps in the synthesis include a regioselective aromatic Claisen rearrangement to install the (1-vinyl)-4-methyl-3-pentenyl substituent and regioselective biomimetic 7-endo and 6-exo phenol epoxide cyclizations to form the cyclic ether moieties.  相似文献   
9.
10.
Michael addition of N-lithio-4-vinyl-azetidin-2-one to several vinyl phosphonates gave adducts which were converted to Δ-1 carbopenems via ozonolysis and an intramolecular Horner-Wittig reaction.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号