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Search Results: 1 - 10 of 81692 matches for " ZHAO Chun-yan "
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Synthesis and biological evaluation of novel conjugates of camptothecin and 5-flurouracil as cytotoxic agents
Yang, Liu;Zhao, Chun-Yan;Liu, Ying-Qian;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000200017
Abstract: a series of novel conjugates of camptothecin and 5-fluorouracil were first synthesized and their cytotoxic activities against two human tumor cell lines (sgc-7901 and a-549) as well as in vitro pharmacokinetic determination of lactone stability were studied. among these compounds, most tested conjugates showed comparable or superior cytotoxic activities to 2, but less potent compared with 1. particularly, conjugates 10b and 10d were highly active against a-549 with ic50 values of 0.45 and 0.38 μmol l-1, respectively. also, the in vitro pharmacokinetic determination of lactone levels of representative compound 10b showed that the biological life span of their lactone forms in human and mouse plasma significantly increased compared with their mother compound 1. quantitative structure-activity relationship (qsar) method was then applied for developing linear models to predict the cytotoxic activities of these derivatives that have not yet been synthesized or experimentally tested. in addition, molecular docking was used to clarify the binding mode of these derivatives to human dna topoisomerase i. the important hydrogen-bonding interactions were observed between these derivatives and their receptor. the results from molecular modeling and qsar study can guide the design of novel conjugates with higher antitumor activity.
On the Solvability of Superlinear and Nonhomogeneous Quasilinear Equations
Gao Jia,Qing Zhao,Chun-yan Dai
Boundary Value Problems , 2009, DOI: 10.1155/2009/156063
Abstract: Using Mountain Pass Lemma, we obtain the existence of nontrivial weak solutions for a class of superlinear and nonhomogeneous quasilinear equations. The key factor in this paper is to use the new idea of near p-homogeneity in conjunction with variational techniques to obtain a new multiplicity result for a vast set of nonlinear equations, such as the mean curvature equation and so on.
On the Solvability of Superlinear and Nonhomogeneous Quasilinear Equations
Jia Gao,Zhao Qing,Dai Chun-yan
Boundary Value Problems , 2009,
Abstract: Using Mountain Pass Lemma, we obtain the existence of nontrivial weak solutions for a class of superlinear and nonhomogeneous quasilinear equations. The key factor in this paper is to use the new idea of near p-homogeneity in conjunction with variational techniques to obtain a new multiplicity result for a vast set of nonlinear equations, such as the mean curvature equation and so on.
Geese PSO Optimization in Geometric Constraint Solving
Cao Chun- Hong,Wang Li- Min,Han Chun-Yan,Zhao Da-Zhe
Information Technology Journal , 2012,
Abstract: Geometric constraint problem is equivalent to the problem of solving a set of nonlinear equations substantially. The constraint problem can be transformed to an optimization n problem. We can solve the problem with GeesePSO optimization. In this paper, an improved algorithm is proposed using the characteristics of the flight of geese for reference. The improved algorithm has superiority over PSO; for one thing, it keeps the population various by ordering all the particles and making each particle fly following its anterior particle; for another thing, it strengthens cooperation and competition between particles by making each particle share more useful information of the other particles. The experiment shows that it can improve the geometric constraint solving efficiency and possess better convergence property than the compared algorithms.
Effects of Starvationand Refeeding on MetabolismofGlucose in Juvenile Parabramis pekinensis
FAN Guo-yan,ZHAO Chun-yan,LI Ying -wen
Journal of Chongqing Normal University , 2010,
Abstract: The effects of short-term starvation and refeeding with different time courses on hepatosomatic index(HIS), liver glycogen and serum glucose in juvenile Parabramis pekinensis is investigated. The fish were randomly allocated into control and treatment groups (20±1)℃,control group was sustained fed, treatment groups were starved for 0, 1,4,7,12 d or starved for 12 d then refed for 1, 4, 7, 15 d respectively. Samples were taken after the process. The result showed that, asstarvation continued,HSI and liver glycogen decreased significantly (P<0.05). Fasting for 4 days, the twoindiceswere(1.34±0.05)and (10.53±4.18)mg . g-1 , and been both markedly below original value;when starved for 12 days, the two indices were (0.96±0.04) and (4.03±0.81)mg . g-1,which were the lowest value ,respectively. As refeeding continued,HSI and liver glycogen increased significantly (P<0.05). The value of liver glycogen after refeeding for 1 d and 15 d had returned to those of original level (P>0.05). During the experiment, serum glucose took on a similar trend with HSI and liver glycogen, and it had a less variation extent. The results indicated that serum glucose had a better stability than the other twoindices; moreover, liver glycogen recovered faster than HSI. So, we suggest that during the starvation, the fish mainly uses glucide as energy source, mobilizes the substance in liver firstly and the change of liver glycogen has a direct relationship with the stability of serum sugar.
Analytical solution of electric potential produced by a direct current point source located in a multilayered spherical volume conductor
分层球形导体中任意位置直流电流元产生电位的解析解

Xiao Chun-Yan,Lei Yin-Zhao,
肖春燕
,雷银照

物理学报 , 2005,
Abstract: A general analytical solution is derived for an electric potential produced by a direct current point source located at any position in a multilayered spher ical volume conductor. Starting from Poisson's equation, the electric potential whose coefficients are rapidly got in the form of matrix expressions is obtained according to the boundary conditions. Simulation for a four-layered spherical volume conductor denoting the scalp, skull, cerebrospinal fluid and brain tissue proves that electric potential in this paper converges more rapidly in the whol e region than that expressed only in spherical harmonics expansion form, and ite rative times decrease. Electric potential contour and current streamline figur es show that it is important to consider the effect of the low conductivity of s kull on electric potential and current flow. The distribution of electric potent ial on the surface of sphere is discussed, which will be useful in electroenceph alography inverse problems, and also in analyzing and interpreting the electric potential measurement.
Soil seed bank research in China: Present status, progress and challenges
中国土壤种子库研究进展与挑战

SHEN You-xin,ZHAO Chun-yan,
沈有信
,赵春燕

应用生态学报 , 2009,
Abstract: 查阅了维普《中文期刊数据库》(1989—2006年)和Web of Science(1985—2006年)中发表的土壤种子库研究文献,按《中国植被》划分的29个植被类型对土壤种子库密度、丰富度和研究方法等数据进行归类总结,共采集到14个植被类型的238个样地信息.结果显示:研究者使用的研究方法及获得的种子库密度和丰富度数据差异巨大.所有研究中采样时间以4和10月最多;样方面积介于78~10000 cm2之间,样方数量介于2~480之间;10 cm×10 cm 和 20 cm×20 cm是最常用的采样方式;总采样面积介于600~500000 cm2之间,并以1000~10000 cm2为最多.土壤种子库密度值变化范围在8 粒·m-2(沙漠)~ 65355粒·m-2(热带雨林的次生林)之间,物种数变化范围在1(温带草原次生光碱斑)~74(热带季雨林)之间,同一植被类型下的变异也相当大.热带的季雨林和雨林的密度值和物种数显著高于温带的针叶林;而人工林的密度和物种数量大于农地,农地又大于裸地.草原、荒漠和草甸的物种数量相对较少.未来的土壤种子库研究需要从广度和深度上进行扩展,并重点加强重要生态系统的土壤种子库长期定位研究以及种子库对策研究,特别是应将这些研究与植被群落的演替、更新和恢复有机地联系起来.同时应加强对不同植被类型的种子库采样、检测方法的探索性研究.
Tracking Desired Trajectory in a Vibro-Impact System Using Backstepping Design

WANG Liang,XU Wei,ZHAO Rui,SUN Chun-Yan,GUO Yong-Feng,

中国物理快报 , 2009,
Abstract: Based on the backstepping design of smooth systems, we developed a new control law to achieve chaos control for a vibro-impact system. In our control strategy, a novel and effective controller is designed such that the output of the vibro-impact system can track any desired trajectory in its domain. The single-degree-of-freedom vibro-impact system is taken as an example to show this control procedure. Numerical simulations are provided to verify the effectiveness of the proposed method.
Will competitiveness of resulting plants of persistent soil seed bank decline? Example from Eupatorium adenophorum
持久性土壤种子库种子萌发的个体竞争能力会衰减吗?——以紫茎泽兰为例

SHEN You-Xin,ZHAO Chun-Yan,
沈有信
,赵春燕

植物生态学报 , 2012,
Abstract: Aims It has been assumed that plants grown from persistent soil seed bank (PSSB) are not less competitive because of soil storage. Our objective was to determine whether the competitiveness of plants of PSSB will decrease. Methods We compared heights and biomass of Eupatorium adenophorum plants grown from fresh seeds and grown from one-year-old buried PSSB seeds with no competition (control) and competition with density of 0.25, 1, 4 and 8 plants·cm–2. We also compared plants grown from fresh seeds and three-year-old buried PSSB seeds with no competition (control) and competition with density of 0.10, 0.17, 0.60 and 2.17 plants·cm–2. The PSSB seeds and fresh seeds were germinated simultaneously, and seedlings were grown in garden pots up to 175 days. Plant height was measured every 15 days and biomass was measured every 30 days (3 replicates). Important findings The height and biomass of plants of one- and three-year-old buried PSSB seeds were lower than for plants germinated from fresh seeds in the control (no competition) and with competition at most measuring times. However, most differences were not statistically significant.
Impact of lymphatic and/or blood vessel invasion in stage II gastric cancer
Chun-Yan Du,Jing-Gui Chen,Ye Zhou,Guang-Fa Zhao
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i27.3610
Abstract: AIM: To determine the prognostic value of lymphatic and/or blood vessel invasion (LBVI) in patients with stage II gastric cancer. METHODS: From January 2001 to December 2006, 487 patients with histologically confirmed primary gastric adenocarcinoma were diagnosed with stage II gastric cancer according to the new 7th edition American Joint Committee on Cancer stage classification at the Department of Gastric Cancer and Soft Tissue Surgery, Fudan University Shanghai Cancer Center. All patients underwent curative gastrectomy with standard lymph node (LN) dissection. Fifty-one patients who died in the postoperative period, due to various complications or other conditions, were excluded. Clinicopathological findings and clinical outcomes were analyzed. Patients were subdivided into four groups according to the status of LBVI and LN metastases. These four patient groups were characterized with regard to age, sex, tumor site, pT category, tumor grading and surgical procedure (subtotal resection vs total resection), and compared for 5-year overall survival by univariate and multivariate analysis. RESULTS: The study was composed of 320 men and 116 women aged 58.9 ± 11.5 years (range: 23-88 years). The 5-year overall survival rates were 50.7% and the median survival time was 62 mo. Stage IIa cancer was observed in 334 patients, including 268 T3N0, 63 T2N1, and three T1N2, and stage IIb was observed in 102 patients, including 49 patients T3N1, 51 T2N2, one T1N3, and one T4aN0. The incidence of LBVI was 28.0% in stage II gastric cancer with 19.0% (51/269) and 42.5% (71/167) in LN-negative and LN-positive patients, respectively. In 218 patients (50.0%), there was neither a histopathologically detectable LBVI nor LN metastases (LBVI /LN , group I); in 51 patients (11.7%), LBVI with no evidence of LN metastases was detected (LBVI+/LN , group II). In 167 patients (38.3%), LN metastases were found. Among those patients, LBVI was not determined in 96 patients (22.0%) (LBVI /LN+, group III), and was determined in 71 patients (16.3%) (LBVI+/LN+, group IV). Correlation analysis showed that N category and the number of positive LNs were significantly associated with the presence of LBVI (P < 0.001). The overall 5-year survival was significantly longer in LN-negative patients compared with LN-positive patients (56.1% vs 42.3%, P = 0.015). There was a significant difference in the overall 5-year survival between LBVI-positive and LBVI-negative tumors (39.6% vs 54.8%, P = 0.006). Overall 5-year survival rates in each group were 58.8% (I), 45.8% (II), 45.7% (III) and 36.9% (IV),
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