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931.
The compound [N-Me-2,2′-Bipy]+[C2B9H12]?-(N-CH3-2,2′-bipyridinium)(dodecahydro-dicarba-nidoundecaborate) has been synthesized, and its structure has been determined. The compound was defined by IR, 11B and 14N NMR, and X-ray photoelectron spectroscopy. Crystal data: C13H23B9N2, M = 304.62, monoclinic crystals, space group P21/c, a = 11.840(4) Å, b = 10.051(3) Å, c = 15.573(6) Å, β = 102.43(3)°, V = 1809.8(10) Å3, Z = 4, d calc = 1.118 g/cm3, R = 0.0607. 相似文献
932.
Huo C Su X Li X Zhang X Li C Wang Y Shi Q Kiyota H 《Magnetic resonance in chemistry : MRC》2007,45(6):527-530
A new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane were isolated from the methanol extract of the needles of Taxus cuspidata. The structures were established as 2alpha,7beta-diacetoxy-5alpha,10beta,13beta-trihydroxy-2(3 --> 20)abeotaxa-4(20), 11-dien-9-one (1) and 2alpha,5alpha,7beta,9alpha,13alpha-pentahydroxy-10beta-acetoxytaxa-4(20),11-diene (2) on the basis of 1D and 2D NMR spectral data and high-resolution FAB-MS analyses. 相似文献
933.
934.
Combination of the enantioselective properties of the two versatile gas-chromatographic chiral stationary phases (CSPs) octakis(3-O-butanoyl-2,6-di-O-n-pentyl)-gamma-CD (Lipodex E) 1 and L-valine-diamide-based CSP Chirasil-Val-C11 2 has been realized by doping the chiral polymer 2 with the nonpolymeric selector 1. The resulting mixed-mode CSP Chirasil-Val(gamma-Dex) 3 was found to have a greatly improved enantioselectivity toward proline and aspartic acid (as N-trifluoroacetyl ethyl or methyl esters) in comparison to the single-mode CSP 2. The presence of the CD selector in 3 extended the scope of gas-chromatographic enantioseparations achievable on 2 to underivatized alcohols, terpenes, and other chiral compounds that are exclusively enantioseparated on 1. 相似文献
935.
Yue Cong William Jia Jing Chen Shuang Song Jin‐Hui Wang Yu‐Hui Yang 《Helvetica chimica acta》2007,90(5):1038-1042
Two new steroidal alkaloids, neoverapatuline ( 1 ) and (1β,3α,5β)‐1,3‐dihydroxyjervanin‐12‐en‐11‐one ( 2 ), together with the four known compounds, veratramine ( 3 ), rubijervine ( 4 ), veratrosine ( 5 ), and veratroylzygadenine ( 6 ), were isolated from the roots and rhizomes of Veratrum nigrum L. Their structures were established through combined analyses of physicochemical properties and spectroscopic evidence. All compounds 1 – 6 were tested for their cytotoxicities in vitro against the human glioma cell line SF188. 相似文献
936.
Two new brominated diterpenes, namely, laurendecumtriol ( 1 ) and 11‐O‐deacetylpinnaterpene C ( 2 ), one new polybromoindole, 2,3,4,6‐tetrabromo‐1‐methyl‐1H‐indole ( 7 ), and six known natural products were isolated and identified from the marine red alga Laurencia decumbens. Their structures were elucidated on the basis of detailed spectroscopic and mass‐spectrometric analysis as well as by comparison with literature data. Based on 2D‐NMR experiments, the previously reported NMR data for pinnaterpene C ( 3 ) were reassigned. 相似文献
937.
SAPO—11分子筛的酸性及催化性能 总被引:9,自引:0,他引:9
用IR及TPD法研究了SAPO-11分子筛的表面酸性质,并以正庚烷裂解和乙醇脱水为探针研究其催化性能。结果表明,SAPO-11分子筛上既有L酸中心,又有B酸中心,表面上存在4个羟基峰。NH_3-TPD测定了SAPO-11的酸强度和酸中心数,并用矩形法求得脱附活化能,SAPO-11系属中等酸强度的分子筛。 相似文献
938.
王永铎 《西北师范大学学报(自然科学版)》2001,(4)
给出了相对C11模的定义 ,并研究了相对C11模的特征与结构 ,证明了相对C11模和C11模的直和仍是相对C11模 相似文献
939.
对海洋假单胞菌7-11(pseudomonas sp.7-11)产蛋白酶进行了培养基的优化,初步确定了促使蛋白酶产率提高的培养基的配方.经过26℃、140r/min、12 h培养,蛋白酶的相对产量可达201.7 IU/mL,比培养基优化前的26.8 IU/mL提高了646%. 相似文献
940.
Wadim Zudilin 《Journal of Number Theory》2009,129(8):1848-1857
We present several supercongruences that may be viewed as p-adic analogues of Ramanujan-type series for 1/π and 1/π2, and prove three of these examples. 相似文献