Intake of msg ( monosodium glutamate ) contraceptive tablet , anti - infection drug leaded to a higher incidence of ds . the results of paternal exposed factors multi - unconditional logistic model showed that smoke , intake of msg and hepatitis were significantly related with ds . other factors , such as drinking leaded to a higher incidence of ds 對(duì)父親單因素統(tǒng)計(jì)分析結(jié)果顯示:在生育ds的父親中,有吸煙史、飲酒史、肝炎患病史、味精用量較多者較對(duì)照組顯著增高,具統(tǒng)計(jì)意義:多因素logistic回歸分析結(jié)果表明吸煙、味精和肝炎與ds發(fā)生呈正相關(guān)。
Next we study the logistic model with both state - dependent delays and continuous delays and feedback control . with the help of coincidence degree theory , some new results for the existence of the postive periodic solution of the system are obtained . also , by constructing suitable lyapunov functional , some sufficient criteria for the uniqueness and globally asymptotic stability of positive periodic solution are established 第二部分研究同時(shí)具有狀態(tài)依賴時(shí)滯和連續(xù)時(shí)滯的反饋控制logistic增長(zhǎng)模型,利用重合度理論研究其正周期解的存在性問(wèn)題,得到了該系統(tǒng)周期正解存在的充分性條件;通過(guò)構(gòu)造適當(dāng)?shù)膌yapunov泛函得到保證該系統(tǒng)存在全局穩(wěn)定周期解的充分性條件。
Based on the summary of recent china ' s and international literature researching tourism , this paper , with a case , which was taken in mianshan resort , located in shanxi province , studied the following contents : 1 ) hiberarchy structure of tourism system of mianshan resort , 2 ) quality evaluation ( ahp method ) on mianshan tourism resource and environmental capacity of mianshan resort , 3 ) travelers attracting area of mianshan resort , 4 ) an optimization model for tourism information transfer , 5 ) logistic model for sustainable development . the intent here was to explore a helpful method and seek an optimum capacity for sustainable development on regional tourism system 本文在綜述旅游系統(tǒng)概念、旅游資源概念、旅游系統(tǒng)研究進(jìn)展的基礎(chǔ)上,運(yùn)用系統(tǒng)分析方法的大系統(tǒng)分解協(xié)調(diào)原理,將旅游系統(tǒng)進(jìn)行分解,再對(duì)各子系統(tǒng)進(jìn)行綜合和協(xié)調(diào),對(duì)客觀旅游系統(tǒng)進(jìn)行整體性、協(xié)調(diào)性、系統(tǒng)性分析,將各部分有序地、合理地組織起來(lái),旨在對(duì)旅游資源、旅游業(yè)可持續(xù)發(fā)展的理論和方法做一些有益的探討,研究尋找旅游需求與供給達(dá)到一個(gè)最佳的結(jié)合點(diǎn)。
The method of modified simplex was applied to optimize the models , and the fitting results show that liu - logistic model was more suitable than logistic model to the actual growth trend of form . taxus chinensis var . mairei population , and the highest growth rate of basal area was the tenth age class , namely the phase when breast diameter was 68 ~ 76 cm 以胸高斷面積代替種群生物量,分別采用logistic常規(guī)模型及劉金福提出的logistic改進(jìn)模型對(duì)南方紅豆杉種群的增長(zhǎng)動(dòng)態(tài)進(jìn)行研究,運(yùn)用改進(jìn)單純形法對(duì)模型進(jìn)行優(yōu)化,擬合結(jié)果表明改進(jìn)模型比logistic常規(guī)模型更符合南方紅豆杉種群的增長(zhǎng)趨勢(shì),南方紅豆杉種群的最大增長(zhǎng)速度出現(xiàn)在第10齡級(jí),即胸徑為68 76cm時(shí)期。