在Goldbach猜想、孪生素数猜想等数论经典问题的研究中,必须处理素变数三角和S(x;α)=sum from n≤to A(n)e(nα),其中α及x≥2是实数,A(n)是 von Mangoldt函数,而 e(α)=e^(2πiα).当α接近于分母较小的分数时,例如时,有渐近公式(参...在Goldbach猜想、孪生素数猜想等数论经典问题的研究中,必须处理素变数三角和S(x;α)=sum from n≤to A(n)e(nα),其中α及x≥2是实数,A(n)是 von Mangoldt函数,而 e(α)=e^(2πiα).当α接近于分母较小的分数时,例如时,有渐近公式(参看文献[1])此处及以下,L代表logx,μ(n)和(?)(n)分别是M(?)bius函数和Euler函数。展开更多
[ Objective ] Study on the changes of chlorophyll fluorescence parameters in Cinnamomumjaponicum var. chenii under NaCl stress. [ Method ] The seedling growth increment, chlorophyll content and chlorophyll fluorescenc...[ Objective ] Study on the changes of chlorophyll fluorescence parameters in Cinnamomumjaponicum var. chenii under NaCl stress. [ Method ] The seedling growth increment, chlorophyll content and chlorophyll fluorescence parameters in leaves of 1-year old Cinnamomum japonicum var. chenii were investigated in field experiment. [ Result] Under NaC1 stress, seedling growth increment reduced and the chlorophyll content decreased to a stable value ; changes of Fv/Fm and Fv/Fo showed identical increasing trend and double peak type. With the aggravation of salt stress, most variations were observed in Fo, correlations among chlorophyll fluorescence parameters presented ＂rise-drop＂ trend （in.the treatment of 7 g/L NaCl）. [ Conclusion] Cirmamomum japonicum vat. chenii is endowed with strong salt resistance and wide adaptability.展开更多
The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The pote...The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The potential sliding mass was divided into a series of vertical slices as well as the traditional slice technique.Equating the external work rate to the internal energy dissipation,the optimum solutions to stability factors were determined by the nonlinear programming algorithm.From the numerical results,it is found that the present solutions agree well with previous results when the nonlinear criterion reduces to the linear criterion,and the nonassociated flow rule reduces to the associated flow rule.The stability factors decrease by 39.7%with nonlinear parameter varying from 1.0 to 3.0.Dilation and nonlinearity have significant effects on the slope stability factors.展开更多
AIM:To evaluate whether weekend or nighttime admission affects prognosis of peptic ulcer bleeding despite early endoscopy.METHODS:Retrospective data collection from four referral centers,all of which had a formal out-...AIM:To evaluate whether weekend or nighttime admission affects prognosis of peptic ulcer bleeding despite early endoscopy.METHODS:Retrospective data collection from four referral centers,all of which had a formal out-of-hours emergency endoscopy service,even at weekends.A total of 388 patients with bleeding peptic ulcers who were admitted via the emergency room between January 2007 and December 2009 were enrolled.Analyzed parameters included time from patients' arrival until endoscopy,mortality,rebleeding,need for surgery and length of hospital stay.RESULTS:The weekday and weekend admission groups comprised 326 and 62 patients,respectively.There were no significant differences in baseline characteristics between the two groups,except for younger age in the weekend group.Most patients (97%) had undergone early endoscopy,which resulted in a low mortality rate regardless of point of presentation (1.8% overall vs 1.6% on the weekend).The only outcome that was worse in the weekend group was a higher rate of rebleeding (12% vs 21%,P = 0.030).However,multivariate analysis revealed nighttime admission and a high Rockall score (≥ 6) as significant independent risk factors for rebleeding,rather than weekend admission.CONCLUSION:Early endoscopy for peptic ulcer bleeding can prevent the weekend effect,and nighttime admission was identified as a novel risk factor for rebleeding,namely the nighttime effect.展开更多
文摘在Goldbach猜想、孪生素数猜想等数论经典问题的研究中,必须处理素变数三角和S(x;α)=sum from n≤to A(n)e(nα),其中α及x≥2是实数,A(n)是 von Mangoldt函数,而 e(α)=e^(2πiα).当α接近于分母较小的分数时,例如时,有渐近公式(参看文献[1])此处及以下,L代表logx,μ(n)和(?)(n)分别是M(?)bius函数和Euler函数。
基金Key Scientific Research Project of Zhejiang Province (2005G12004)~~
文摘[ Objective ] Study on the changes of chlorophyll fluorescence parameters in Cinnamomumjaponicum var. chenii under NaCl stress. [ Method ] The seedling growth increment, chlorophyll content and chlorophyll fluorescence parameters in leaves of 1-year old Cinnamomum japonicum var. chenii were investigated in field experiment. [ Result] Under NaC1 stress, seedling growth increment reduced and the chlorophyll content decreased to a stable value ; changes of Fv/Fm and Fv/Fo showed identical increasing trend and double peak type. With the aggravation of salt stress, most variations were observed in Fo, correlations among chlorophyll fluorescence parameters presented ＂rise-drop＂ trend （in.the treatment of 7 g/L NaCl）. [ Conclusion] Cirmamomum japonicum vat. chenii is endowed with strong salt resistance and wide adaptability.
基金Project(200550)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(200631878557)supported by West Traffic of Science and Technology of China
文摘The soil masses of slopes were assumed to follow a nonlinear failure criterion and a nonassociated flow rule.The stability factors of slopes were calculated using vertical slice method based on limit analysis.The potential sliding mass was divided into a series of vertical slices as well as the traditional slice technique.Equating the external work rate to the internal energy dissipation,the optimum solutions to stability factors were determined by the nonlinear programming algorithm.From the numerical results,it is found that the present solutions agree well with previous results when the nonlinear criterion reduces to the linear criterion,and the nonassociated flow rule reduces to the associated flow rule.The stability factors decrease by 39.7%with nonlinear parameter varying from 1.0 to 3.0.Dilation and nonlinearity have significant effects on the slope stability factors.
文摘AIM:To evaluate whether weekend or nighttime admission affects prognosis of peptic ulcer bleeding despite early endoscopy.METHODS:Retrospective data collection from four referral centers,all of which had a formal out-of-hours emergency endoscopy service,even at weekends.A total of 388 patients with bleeding peptic ulcers who were admitted via the emergency room between January 2007 and December 2009 were enrolled.Analyzed parameters included time from patients' arrival until endoscopy,mortality,rebleeding,need for surgery and length of hospital stay.RESULTS:The weekday and weekend admission groups comprised 326 and 62 patients,respectively.There were no significant differences in baseline characteristics between the two groups,except for younger age in the weekend group.Most patients (97%) had undergone early endoscopy,which resulted in a low mortality rate regardless of point of presentation (1.8% overall vs 1.6% on the weekend).The only outcome that was worse in the weekend group was a higher rate of rebleeding (12% vs 21%,P = 0.030).However,multivariate analysis revealed nighttime admission and a high Rockall score (≥ 6) as significant independent risk factors for rebleeding,rather than weekend admission.CONCLUSION:Early endoscopy for peptic ulcer bleeding can prevent the weekend effect,and nighttime admission was identified as a novel risk factor for rebleeding,namely the nighttime effect.
