42 research outputs found

    宝黛相争 谁伴宝玉欧洲游?

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    部门经理应当如何处理公与私的矛盾?领导面对复杂的人际关系,应该采取何种处事原则?家族企业中的空降CEO,如何应对各种人事矛盾避免引火烧身

    一类具有抗肿瘤活性的新型紫杉烷卤代衍生物

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    一类具有抗肿瘤活性的新型紫杉烷卤代衍生物,其特征在于:所述为具有如结构通式的新型紫杉烷卤代衍生物及以其作为活性成分的抗肿瘤药物如式I,其中R为H或Ac;R’具有下右式结构,其中R”为选自-OMe,-OH的取代基,X为选自Cl,Br中的卤素。本发明中所示的化合物对于白血病细胞(K562),非小细胞肺癌细胞(A549),结肠癌细胞 (HT-29),卵巢癌细胞(OVCAR-3),人成骨肉瘤细胞(Saos-2),乳腺癌细胞 (MCF-7)等多种肿瘤细胞系均表现出与紫杉醇相似的细胞毒性,具有作为抗癌药物开发的价值。带填

    可压混合层流动转捩到湍流的直接数值模拟

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    可压混合层流动转捩到湍流的直接数值模拟

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    采用五阶精度迎风紧致格式和六阶对称紧致格式,结合三阶R-K方法求解可压缩三维Navier-Stokes方程,直接数值模拟了时间发展平面混合层流。给出了对流Mach数M_C=0.8,Reynolds数Re=200时流动从初始扰动为一对相等且相反的斜波开始,经过失稳发展形成Λ涡、马蹄涡和蘑茹云等拟序结构,然后破碎为小尺度、再破碎为更小尺度的涡结构,形成以小尺度运动为主导的流动,最终达到湍流

    A QSRR Model for Identification of Taxanes and Their Metabolites By Prediction Retention Time on UFLC

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    Ultra-flow liquid chromatography (UFLC) is one of the most promising devices in separation as for its high throughput, good chromatographic performance and high speediness. We intended to build a QSRR model to predict the gradient retention time of taxanes on UFLC, so as to aid in the identification of the metabolites and optimization of separation conditions. We obtained the retention data of 28 taxanes under the same gradient elution, and a large set of molecular descriptors including the semi-empirical descriptors and the E-dragon descriptors were computed to characterize the structures. Genetic algorithm-partial least square (GA-PLS) was adopted to choose variables, then the chosen variables were used to build models for prediction of retention time by multi-linear regression (MLR), artificial neural network (ANN), and support vector machine (SVM) separately. At last, we build a good model by SVM with the statistical results of R2=0.94, the absolute error between calculated and real retention time less than 1 minutes for external test set. In order to test the generalization of this model, the retention time of metabolites about paclitaxel and cephalomannie were also predicted, through the predicted retention time, we can discriminate metabolites at different sites. Our QSRR model is not only useful in identification of metabolites; but also will help in separation and identification of new compounds

    Cut tobacco supply discharger at the back of cigarette making machine

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    本实用新型涉及卷烟机后身的供丝系统,具体地说是一种卷烟机后身供丝落料器,包括蝶阀、负压风室、预分配箱、闸门气缸、闸板、预分配辊及变频电机,所述负压风室与预分配箱相连通、共同位于落料器壳体内的上方,蝶阀安装在落料器壳体上、并与负压风室相连通;闸门气缸的一端与负压风室铰接,另一端连接有位于预分配箱下方的闸板,闸板的一端铰接于落料器壳体上,另一端为自由端;闸板的下方为预分配贮料区,该预分配贮料区的一侧设有通过变频电机驱动旋转的预分配辊,预分配辊上匀布有落料针。本实用新型具有结构简单,互换性强,效率高,成本低,易于保养维护等特点

    2002~2003年北半球中纬地区臭氧总量TOMS与地面观测的非常差异

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    贵州丽松鼠亚科动物资源调查

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    松鼠科丽松鼠亚科动物具有分布广、适应性强的特点,因种群量大而成为影响森林生态平衡的重要动物之一。贵州喀斯特地貌发育典型,植被类型多样,且在兽类区划上位于华中区和华南区的过渡地带,拥有较高的丽松鼠动物资源量,但长期以来缺乏系统的资源调查与数据整理。为此,本研究利用文献资料,结合采样调查与红外相机监测对贵州丽松鼠亚科动物进行了初步调查整理,结果表明:(1)贵州分布的丽松鼠主要包括赤腹松鼠、隐纹花松鼠、红腿长吻松鼠和珀氏长吻松鼠。(2)4种中,赤腹松鼠捕获率为0.64%、隐纹花松鼠为0.15%、红腿长吻松鼠0.089%、珀氏长吻松鼠0.11%。赤腹松鼠分布广泛,遍布全省,为优势种; 红腿长吻松鼠分布相对狭窄,此外,贵州丽松鼠亚科动物集中分布在黔东北低山丘陵州和黔南低山河谷省,黔西西北部高原州物种分布最少。(3)随海拔的上升丽松鼠的分布逐渐减少,4种丽松鼠主要集中分布在900~1500 m之间海拔地带。(4)赤腹松鼠多活动在以马尾松、杉木等为主的针叶林和针阔混交林,红腿长吻松鼠活动在具开阔林窗的阔叶林带,珀氏长吻松鼠则经常出没在农耕地附近和灌丛中,阔叶林、针阔混交林则是隐纹花松鼠最常利用的生境。本文基本摸清贵州丽松鼠动物的分布与资源状况,将对这类动物资源的保护管理与科学研究提供重要的基础资料
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