新型大屏幕彩电的Y/C分离技术

阐述了彩色电视机Y/C分离技术的发展 ,分析了不同Y/C分离方法的工作原理及对电视图像清晰度的影响 ,并给出了新型大屏幕彩电的Y/C分离电路 .     

基于金属有机框架材料的C2烃类吸附分离研究进展

乙烷、乙烯、乙炔这3种C2烃类在石油化工领域应用广泛,其分离纯化过程是进行化工生产的一个重要步骤．因C2烃类物理性质与分子尺寸都比较接近,对其进行分离提纯是分离领域的难题,目前工业上采用的主要是低温蒸馏法,但其能耗大,对设备要求高;吸附分离法被认为是一种能够降低能耗的有效手段,作为吸附剂的金属有机框架（MOFs）材料因其结构多样,比表面积高,孔道易于设计和功能化而备受关注,同时被认为在C2烃类节能分离领域具有很好的应用前景．本文对近年来基于MOFs材料的C2烃类吸附分离的研究作了归纳总结,主要从MOFs材料结构与分离性能间的关系出发,以不同的分离机制对C2烃类的分离作了介绍说明,探讨了其所存在的问题,并进行了展望．      

TC9090AN/F亮度/色度分离电路

本文简述了亮度／色度分离电路原理，以及为了实现数字Y／C分离，TC9090AN／F集成块中含有一路8位A／D变换器和二路D／A变换器，以便把模拟复合视频信号变成数字信号，再实施分离，然后把分离的数字Y和C变成模拟Y和C信号。     

苦石莲的化学成分研究

研究了苦石莲Caesalpinia minax Hance的化学成分.采用硅胶柱色谱、中压液相色谱以及高效液相色谱等多种现代分离手段进行分离纯化,通过理化常数测定和光谱分析鉴定化学结构.从苦石莲甲醇提取物中分离得到了7个卡萨烷型二萜类化合物,即caesalpinin MB(1),7-acetoxybonducellpin C(2),bonducellpin C(3),caesalpinin K(4),bonducellpin G(5),1-deacetylcaesalmin C(6),norcaesalpinin E(7).其中化合物1,3,5,6为首次从本种植物中分离得到.     

禽肉中弯曲菌的分离、PFGE和DGGE分型

随机选取某肉菜市场8份鸡肉和鸭肉样品中的弯曲菌(Campylobacter),分别采用Bolton和Preston肉汤增菌,然后以Skirrow、mCCDA选择分离培养和膜过滤的方法同时分离,运用脉冲场凝胶电泳(PFGE)和变性梯度凝胶电泳(DGGE)对分离出的菌株进行分子水平的分型和溯源.结果表明:共有6份样品污染了空肠弯曲菌(C.jejuni)或结肠弯曲菌(C.coli);Preston肉汤增菌、mCCDA选择分离培养法的分离效果最好;4份样品被同一种C.coli污染,2份样品分别污染了2种C.jejuni和3种C.coli;与PFGE相比,DGGE分型方法的灵敏度略低,但更快速、成本更低,且稳定、准确,可用于食品中弯曲菌的快速分型.     

富勒烯的提取及分离

本文用柱色层法研究了C50混合物的提取及分离，并对影响C60分离的条件进行了有益的探讨．     

聚己内酰胺分离纯化缩宫素粗品研究

通过考察在不同乙腈浓度等度洗脱条件下,缩宫素在聚酰胺色谱柱上的保留,研究了聚酰胺对缩宫素的分离机理,建立并优化了聚酰胺对缩宫素粗品的粗分离方法,并与反相C18分离效果进行对比.缩宫素在聚酰胺色谱柱上的保留呈现典型的氢键吸附和疏水作用吸附共同作用的混合吸附模式;在优化的纯水等度洗脱分离缩宫素粗品的条件下,样品栽量可达9.38 mg/mL介质,纯度可达65.8%,回收率72.1%.研究结果表明,聚酰胺纯水等度洗脱分离缩宫素粗品有着与传统反相C18分离基本相当的效果,与反相C18相比还有着样品栽量高、经济、安全和环保等优点.     

C2H4-CO2在Co-丝光沸石上吸附分离研究

用重量法测定了C2H4和CO2在Co-丝光沸石上的吸附等温线和吸附扩散动力学曲线,并对吸附平衡等温线和扩散曲线模拟计算,拟合很好. 研究表明,在Co-丝光沸石上,C2H4 的平衡吸附量远大于CO2的;而C2H4的吸附扩散速率与CO2的接近. 因此利用平衡吸附原理,用Co-丝光沸石可将C2H4-CO2中的CO2吸附下来,得到100%的C2H4. 采用动态吸附法考察了吸附温度、流速、浸渍量以及活化温度对Co-丝光沸石吸附分离C2H 4-CO2的影响规律,分析得出吸附剂的最佳操作条件. 采用Co-丝光沸石来分离C2H 4-CO2,分离因数大,选择吸附的量也较大,床层利用率高,脱附较易.     

香附化学成分的研究

分离鉴定香附的化学成分,为后期的体内活性筛选提供样品.应用硅胶柱层析、凝胶柱层析、薄层制备等方法分离香附中的化学成分,并通过核磁共振等手段对化合物进行结构解析.从香附中分离得到3个化合物,分别为α-香附酮(1)、cyperotundone(2),oxyphyllenones C(3).Oxyphyllenones C为oxyphyllenones B的一种构型异构体,是未见文献报道新化合物.     

H_2C=N-系列气态分子的结构和气相酸度的INDO研究

本文用INDO方法优化了H_2C=NH、H_2C=NCH_3、H_2C=NSH及H_2C=N~-、H_2C=NCH_2~-、H_2C=NS~-的几何构型,研究了它们的气相酸度(质子分离能),所得结果与实验值在次序上一致。     

哒螨酮在甲醇中的光解

以氙灯为光源，农药哒螨酮在甲醇溶剂中的光解动力学符合一级动力学规律，通空气对哒螨酮的光解速率影响不大，而通氮气时可明显促进其光解，产物分析表明，哒螨酮在甲醇中光解断裂碳硫键，生成对叔丁基苯乙烷－2特丁基－4－巯基－4－氯哒嗪－3－醇，前可进一步氧化成对叔丁基苯甲酸和对叔丁基苯甲酸甲酯。     

A tree-ring-based reconstruction of the Yimin River annual runoff in the Hulun Buir region, Inner Mongolia, for the past 135 years

Based on the relationships between the regional tree-ring chronology(RC) of moisture-sensitive Pinus sylvestris var.mongolica and the monthly mean maximum temperature,annual precipitation and annual runoff,a reconstruction of the runoff of the Yimin River was performed for the period 1868-2002.The model was stable and could explain 52.2% of the variance for the calibration period of 1956-2002.During the past 135 years,21 extremely dry years and 19 extremely wet years occurred.These years represented 15.6% and 14.1% of the total study period,respectively.Six severe drought events lasting two years or more occurred in 1950-1951,1986-1987,1905-1909,1926-1928,1968-1969 and 1919-1920.Four wetter events occurred during 1954-1959,1932-1934,1939-1940 and 1990-1991.Comparisons with other tree-ring-based streamflow reconstructions or chronologies for surrounding areas supplied a high degree of confidence in our reconstruction.Power spectrum and wavelet analyses suggested that the reconstructed annual runoff variation in the Hulun Buir region and surrounding area could be associated with large-scale atmospheric-oceanic variability,such as the Pacific Decadal Oscillation(PDO) and El Ni o-Southern Oscillation(ENSO),and sunspot activity.     

间苯二甲酰胺Gemini表面活性剂的合成及性能

采用3-二甲氨基丙胺和间苯二甲酰氯为原料,合成二(3-二甲氨基丙基)间苯二甲酰胺,再分别与溴代正十二烷、溴代正十四烷和溴代正十六烷反应制得3种含酰胺键的Gemini阳离子表面活性剂(C12-N-C12、C14-N-C14、C16-N-C16).采用IR、1 H-NMR、元素分析表征了其结构.测定其临界胶束浓度(CMC)分别为5.96×10-4、1.03×10-4、6.25×10-5 mol·L-1;表面张力(γCMC)分别为40.83、38.76、38.08 mN·m-1;Krafft点分别为0、0、12℃,并研究了其乳化性、泡沫性质.     

Decadal-centennial-scale change in Asian-Pacific summer thermal contrast and solar activity

To study the temporally varying features of summer thermal contrast between the Asian continent and the adjacent ocean on decadal-centennial time scales and the links between thermal contrast and solar irradiance, we used a time series of the reconstructed Asian-Pacific oscillation index and solar irradiance over the past millennium. The results showed that thermal contrast in the Asian monsoon region has quasi-90-year, 10?C13-year, and 3?C7-year periods. On the centennial time scale, thermal contrast showed three abrupt changes, occurring in 1305?C1315, 1420?C1430, and 1625?C1635. There is a significant positive correlation between thermal contrast and solar irradiance, which is particularly strong at 250-year, 120?C160-year, 60?C70-year, and quasi-15-year periods. The three abrupt changes in thermal contrast corresponded to a significantly weakening or strengthening of solar irradiance, lagging 12?C22 years behind the solar irradiance, which possibly reflects an effect of solar irradiance on the abrupt change in Asian monsoon climate on the centennial time scale. On the decadal time scale, the abrupt change in the thermal contrast was not closely associated with solar irradiance, which implies that solar activity may not be a major factor affecting the decadal abrupt change in Asian-Pacific thermal contrast. Relative to thermal contrast, the decadal abrupt change in Northern Hemispheric annual mean surface temperature is more closely associated with solar activity, while its centennial abrupt change has a weaker relationship with solar activity.     

Climatic changes in the Twenty-four Solar Terms during 1960–2008

The temperature thresholds and timings of the 24 climatic Solar Terms in China are determined from a homogenized dataset of the surface air temperature recorded at 549 meteorological stations for the period 1960?C2008 employing the ensemble empirical mode decomposition method. Changes in the mean temperature and timing of the climatic solar terms are illustrated. The results show that in terms of the mean situation over China, the number of cold days such as those of Slight Cold and Great Cold has decreased, especially by 56.8% for Great Cold in the last 10 years (1998?C2007) compared with in the 1960s. The number of hot days like those of Great Heat has increased by 81.4% in the last 10 years compared with in the 1960s. The timings of the climatic Solar Terms during the warming period (around spring) in the seasonal cycle have advanced significantly by more than 6 d, especially by 15 d for Rain Water, while those during the cooling period (around autumn) have delayed significantly by 5?C6 d. These characteristics are mainly due to a warming shift of the whole seasonal cycle under global warming. However, the warming shift affects the different Solar Terms to various extents, more prominently in the spring than in the autumn. The warming tendencies for Rain Water, the Beginning of Spring, and the Waking of Insects are the largest, 2.43°C, 2.37°C, and 2.21°C, respectively, for the period 1961?C2007 in China as a whole. Four particular phenology-related climatic Solar Terms, namely the Waking of Insects, Pure Brightness, Grain Full, and Grain in Ear, are found to have advanced almost everywhere. In semi-arid zones in northern China, advances of the timings of these four climatic Solar Terms are significant, 12?C16, 4?C8, 4?C8, and 8?C12 d, respectively, for the period 1961?C2007. These quantitative results provide a scientific base for climate change adaptation, especially in terms of agricultural planning and energy-saving management throughout a year.     

关于笛卡尔积码的广义Hamming重量的分析

在文献[1 0 ] 中 ,由旧码C1 、C2 构造了一类新码C1 C2 ———笛卡尔积码。本文根据文献[1 ]中提出的广义Hamming重量的定义 ,分析了笛卡尔积码与旧码C1 、C2 的广义Hamming重量的关系 ,给出了几个有意义的结果     

不同溶剂浸取红豆杉细胞中的紫杉醇的研究

用7种单一溶剂浸取红豆杉细胞中的紫杉醇,研究表明,甲醇有最好的浸取效果,紫杉醇含量占细胞干重的0.03315％,在23种混合溶剂中,CH3COOC2H5/C2H5OH,CH3COCH3/CH3OH,CH3COCH3/C2H5OH,CH3OH/CHCl3浸取效果最好,其紫杉醇含量占细胞干重分别为0.05166％,0.04923％,0.04276％,0.03981％.     

Studies on induction hardening of powder-metallurgy-processed Fe-Cr/Mo alloys

Induction hardening of dense Fe-Cr/Mo alloys processed via the powder-metallurgy route was studied. The Fe-3Cr-0.5Mo, Fe-1.5Cr-0.2Mo, and Fe-0.85Mo pre-alloyed powders were mixed with 0.4wt%, 0.6wt%, and 0.8wt% C and compacted at 500, 600, and 700 MPa, respectively. The compacts were sintered at 1473 K for 1 h and then cooled at 6 K/min. Ferrite with pearlite was mostly observed in the sintered alloys with 0.4wt% C, whereas a carbide network was also present in the alloys with 0.8wt% C. Graphite at prior particle boundaries led to deterioration of the mechanical properties of alloys with 0.8wt% C, whereas no significant induction hardening was achieved in alloys with 0.4wt% C. Among the investigated samples, alloys with 0.6wt% C exhibited the highest strength and ductility and were found to be suitable for induction hardening. The hardening was carried out at a frequency of 2.0 kHz for 2-3 s. A case depth of 2.5 mm was achieved while maintaining the bulk (interior) hardness of approximately HV 230. A martensitic structure was observed on the outer periphery of the samples. The hardness varied from HV 600 to HV 375 from the sample surface to the interior of the case hardened region. The best combination of properties and hardening depth was achieved in case of the Fe-1.5Cr-0.2Mo alloy with 0.6wt% C.     

Carbon loss from an unprecedented Arctic tundra wildfire

Arctic tundra soils store large amounts of carbon (C) in organic soil layers hundreds to thousands of years old that insulate, and in some cases maintain, permafrost soils. Fire has been largely absent from most of this biome since the early Holocene epoch, but its frequency and extent are increasing, probably in response to climate warming. The effect of fires on the C balance of tundra landscapes, however, remains largely unknown. The Anaktuvuk River fire in 2007 burned 1,039 square kilometres of Alaska's Arctic slope, making it the largest fire on record for the tundra biome and doubling the cumulative area burned since 1950 (ref. 5). Here we report that tundra ecosystems lost 2,016?±?435?g?C?m(-2) in the fire, an amount two orders of magnitude larger than annual net C exchange in undisturbed tundra. Sixty per cent of this C loss was from soil organic matter, and radiocarbon dating of residual soil layers revealed that the maximum age of soil C lost was 50 years. Scaled to the entire burned area, the fire released approximately 2.1?teragrams of C to the atmosphere, an amount similar in magnitude to the annual net C sink for the entire Arctic tundra biome averaged over the last quarter of the twentieth century. The magnitude of ecosystem C lost by fire, relative to both ecosystem and biome-scale fluxes, demonstrates that a climate-driven increase in tundra fire disturbance may represent a positive feedback, potentially offsetting Arctic greening and influencing the net C balance of the tundra biome.     

单个红细胞的拉曼光谱研究

研究了不同物种的血红细胞的拉曼光谱,采用一个波长为785nm的半导体激光束来囚禁血红细胞和激发血红细胞的拉曼光谱。结果显示不同物种血红细胞的拉曼光谱在1603cm^-1苯丙氨酸和色氨酸的C=C平行振动模及1616cm^-1酪氨酸和色氨酸的C=C拉伸模有明显的差异,这可以用来作为不同种血红细胞鉴定的特征标记。表明激光镊子拉曼光谱技术可以成为血红细胞分析的有效手段。