共查询到20条相似文献,搜索用时 100 毫秒
1.
2.
包容生态因子的广义Logistic模型 总被引:10,自引:0,他引:10
以Logistic模型为代表的种群(x)生长模型,仅依赖于时间(t),X=f(t),它是表达某一环境下生物过程的数学模型,其增长率参数(μ)为常数。本文发展了一种包含生态因子的广义Logistic模型,X=f(P,t),p表示生态因子,认为增长率是与生态因子有关的参数:μ=μ0f(p),该模型可以概括在不同环境下种群增长的重复试验,使用作物分期播种资料,建立了水稻干物质积累过程与生育阶段(时间)、播种期、太阳辐射、温度之间的关系,结果表明:该模型可以解释干物重变异的96.9%。 相似文献
3.
为探讨HCV/HBV 复合疫苗的可行性,将合成的丙型肝炎病毒(HCV)复合多表位抗原基因PCX与HBsAg 基因连接成PCXS基因,与β-半乳糖苷酶(GZ)基因融合后在大肠杆菌及减毒鼠伤寒沙门氏菌中获得表达.目的蛋白GZ-PCXS可被抗-HBs 及抗-HCV 抗体所特异识别.GZ-PCXS抗原皮下注射免疫ICR小鼠后,诱发了较高水平的抗-GZ-PCXSIgG反应.构建的重组减毒鼠伤寒沙门氏菌SL3261(pWR/PCXS)口服免疫小鼠后,诱发了高水平的CD8+ T细胞增殖反应及抗GZ-PCXSIgG反应.所有免疫小鼠均未见明显的毒副作用.该研究揭示,HCV/HBV 复合抗原可诱发特异性体液免疫及细胞免疫应答,而活菌苗口服可能是理想的免疫途径,为HCV/HBV 双价疫苗研究提供了一定的理论及实验依据. 相似文献
4.
本文报道对中国新疆东部一起戊型肝炎流行高峰期间,由HE患者烘便中分离到的型肝炎病毒中国XT-179株进行全基因cDNA克隆、核苷酸和氨基酸序列测定及分析结果。所阐明的HEV-XT-179株基因组全序列由7194个核苷酸和3'端的多聚腺嘌呤核苷酸尾组成。四种核苷酸的含量腺嘌呤(A)为17.0%,胞嘧啶(C)为31.9%,鸟嘌呤(G)为26.0,尿嘧啶(U)为25.1%。G+C含量为57.9%。全基因 相似文献
5.
小兴安岭阔叶红松林凋落物产量及动态的研究 总被引:7,自引:0,他引:7
小兴安岭阔叶红松林凋落物产量及动态的研究刘传照,李景文,潘桂兰,李传荣(东北林业大学红松研究所,黑龙江带岭153106)LitterProductionandDynamicsinBroadleavcd-KoreanPineForestsinXiaoxinganMountaiils¥LiuChuanzhao;LiJingwen;PanGuilan;LiChuanrong(InstituteofKoreanPineStudies,NortbeastForestryUniversity,Dailing,Heilongjiang153106).ChneseJournalofEcology,1993,12(6):29-33.Three-yearstudywasdoneonlitterproductionanddynamicsunderbroadleaved-KoreanpineforestsintheXiaoxinganMountains。Resultsshowedthatannuallitterfallis4.25±0.17t.ha ̄(-1).yr ̄(-1).Amongtotallitterfall,leaflit 相似文献
6.
鼎湖山针阔叶混交林的第一性生产力研究 总被引:18,自引:1,他引:17
本文应用“树木收获法”和“气体分析法”,结合凋落物收集数据,综合测定了鼎湖山针阔叶混交林中的各种群第一性生产力以及群落的光。进一步综合分析表明,该群落的叶面积指数为11;生物量为261t·hm ̄(-2);总生产力约为117.6t·hm ̄(-2)·a ̄(-1),光能利用效率为12%;第一性生产力为20.9t·hm ̄(-2)·a ̄(-1)。由于该群落是南亚热带演替系列中间阶段的代表性类型,因而本研究结果有助于了解本地带植被动态过程生产力发展规律和对能量的利用状况。 相似文献
7.
中国潜在植被生产力的分布与模拟 总被引:15,自引:1,他引:15
利用中国植被净第一性生产力NPP(netprimaryproductivity)的散点测量数据及中国一般气象站气候记录资料,并根据附近气象站数据进行地理位置相关插值,采用Penman方法计算潜在蒸散,用Thornthwaite的土壤水分处理方法,计算了NPP测定位点的水分平衡。结果表明NPP与生长季实际蒸散、总蒸散、潜在蒸散显著相关,与干燥度成负相关。从生长季的实际蒸散、干燥度指标两参数出发,建立了WBINPP模型:NPP=2.55·GAE·e-4.20922-1.9665AI。该模型考虑了植被生产力形成机制,与NPP实测值相关性高达0.842,高于国际上著名NPP模型Miami模型、ThornthwaiteMemorial模型和Chikugo模型(相关系数为0.655~0.732)。最后利用EIS软件对全国潜在NPP分布格局进行了分析,从东南到西北逐渐减少,最大值出现在海南和台湾,大于22t·hm-2·a-1,长江中下游地区12~16t·hm-2·a-1,华北平原为8~12t·hm-2·a-1,东北地区为4~8t·hm-2·a-1;草原地区为2t·hm-2·a-1左右,干旱荒漠小于2t·hm-2·a-1。 相似文献
8.
中立型时滞模型周期正解的一个充分条件 总被引:3,自引:0,他引:3
研究了一类中立型时滞模型:N’(t)=N(t)「α(t)-β(t)N(t)-b(t)N(t-τ(t))-c(t)N’(t-τ(t))」周期正解的存在性,其中α(t),β(t),b(t),c(t),τ(t)是周期T的非负连续函数。一个新的充分条件被给出,这一结果肯定的回答了文「1」的分开问题9.2。 相似文献
9.
10.
鹤山南亚热带草坡生态系统的生物量和生产力研究 总被引:1,自引:0,他引:1
以能量利用效率研究为中心,系统研究并分析了鹤山南亚热带草坡多年的光合作用与总第一性生产力、生物量与生物量增量、气候生产力模型和能量利用效率等能量学特征。草坡的总生物量为11.30t·(hm)-2·a-1,其生物量增量为1.398t·(hm)-2·a-1;草坡的总第一性生产力为45.54t·(hm)-2·a-1,净第一性生产力为9.108t·(hm)-2·a-1,用于净光合作用耗热105.5MJ·m-2·a-1,净光合耗热中又仅有21.1MJ·m-2·a-1,用于净第一性生产力,净第一性生产力中又仅有3.24MJ·m-2·a-1用于生物量增量;草坡生态系统的光能利用效率为0.07%。草坡的能量利用效率是很低的 相似文献
11.
The cyclic nature of the epidemic process in Bulgaria was studied by various methods (spectral analysis, etc.), forming a system. The morbidity dynamics in 10 infectious diseases (scarlet fever, rubella, measles, epidemic parotitis, whooping cough, diphtheria, typhoid fever, enterocolitis, bacterial dysentery, viral hepatitis) over the years of 1909-1983 were studied and cycles covering the periods of 3-4, 5-6, 10-11 and over 16 years were established. The data on the relative part of cyclic processes in the registered morbidity of infectious diseases, as well as information on the prognostication of the spread of infections in the absence of vaccinal prophylaxis, are presented. 相似文献
12.
A O Ovezov A Ia Mindlina A N Gerasimov V D Beliakov 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1991,(9):40-44
The authors analyze the morbidity structure in five enteric infections (typhoid fever, dysentery caused by Shigella flexneri and Shigella sonnei, hepatitis A, and hepatitis E (non A, non B) with the fecal/oral mechanism of the agent transmission) in three towns of Turkmenia and in the town of Novomoskovsk, Tula Province. The incidence of S. sonnei dysentery was found higher in Novomoskovsk and that of the rest enteric infections under study in Turkmenia. The incidence of typhoid fever and hepatitis E was the highest among schoolchildren and adults, whereas preschool children suffered mostly from hepatitis A and S. sonnei dysentery. The authors discuss the specific features of the epidemic process manifestation in enteric infections. 相似文献
13.
Mefod'ev VV Ustiuzhanin IuV Kozlov LB Tsokova TN Fol'mer AIa 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2007,(2):14-17
Using data on long-term dynamics of epidemic process of acute enteric infections enteric with aqueous route of transmission (typhoid fever, shigellosis caused by Shigella flexneri, hepatitis A, rotavirus gastroenteritis, etc.)the equation of regression was developed with the help of Chebyshev's polynoms. Predicted incidences of these infections for 2005 were on 61.2-99.5% in agree with the real ones on two territories of north region of West Siberia. Predicted incidence for 2006 is reflecting tendencies of epidemic process of mentioned infections. 相似文献
14.
G P Zhdanov T K Konopleva S N Davydova V A Nikulin V I Antonov 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1983,(3):56-60
The analysis of some features of the course of the epidemic process of viral hepatitis on the territory of the Ryazan region is presented. Periodic rises and falls in viral hepatitis morbidity, varying in their regularity (4-6 years), have been registered in the region. The general level and the seasonal distribution of viral hepatitis morbidity are determined by the morbidity rate among children, the increase in the proportion of children of senior school age being observed in recent years. 相似文献
15.
D Kh Fomin Ia N Bogach T V Vlokh L V Shevchenko 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1988,(2):26-29
The previously established zonal character of the prevalence of viral hepatitis A in the Ukraine is a stable epidemiological regularity observed for more than 30 years (1952-1985). Zonal differences in the dynamics of the epidemic process of viral hepatitis A were established. These differences became particularly hepatitis manifest in the years of periodic rises in the morbidity rate which is also irregular within zonal and regional boundaries. The main typological variants of the dynamics of the epidemic process ("urban" and "rural") were defined. Typological approach appears to be useful in the provision of information necessary for the proper functioning of epidemiological surveillance and for taking measures aimed at epidemics control. 相似文献
16.
During the chronic water epidemic of typhoid fever in Tajikistan in 1996-1997 specific features of the epidemic process dynamics in groups of servicemen were studied in several cities. The infective agent was proved to be transmitted by the alimentary route and through everyday contacts, the water route of transmission playing the most important role. The early clinical and epidemiological signs of the water outbreak of typhoid fever and the risk factors were established. The clinical and epidemiological aspects of vaccination were analyzed. 相似文献
17.
M D Aleinik V S Krivitskaia T F Riabikova E A Grinshtein I K Makarevich 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1979,(1):59-64
On the example of 4 cites of the RSFSR under conditions of expected epidemic threat a possibility was shown of directed influence on the viral hepatitis A epidemic process of preseasonal gamma-globulin prophylaxis conducted in 90% of "organized" children, aged from 1 to 12 years. The dose used was 0.75 ml of a 10% preparation. The method of Gorky Institute of Epidemiology and Microbiology was used to prognosticate the morbidity. It is recommended to improve the tactics of preseasonal gamma-globulin prophylaxis with consideration to the data of the viral hepatitis prognosis. 相似文献
18.
The study of patients from 10 foci of acute viral hepatitides for the presence of HBsAg (in the passive reverse hemagglutination test) and anti-hepatitis A virus IgM (in the radioimmunoassay) has shown high frequency and variability in the spread of hepatitis non-A, non-B, the prevalence of adults aged 20-29 years and children aged 2-4 years among persons involved into the epidemic process and the tendency towards an increase in the proportion of hepatitis non-A, non-B in the total number of cases of viral hepatitides in the republic. 相似文献
19.
Sharapov MB Favorov MO Iashina TL Onishchenko GG Asadov DA Chorba TL 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2000,(3):35-39
Official annual statistical data on morbidity in acute viral hepatitides (AVH), including the number of lethal cases, for 1985-1995 were analyzed. Mortality rates per 100,000 of the population at the period of 11 years were calculated for different age groups, sex and the place of residence. 396 and 99 patients were examined for the presence of serological markers of hepatitides A, B and E, respectively, at the periods of epidemic rises in morbidity and satisfactory epidemic situation. In the course of 11 years AVH caused the death of 22,405 persons. In 1985-1987 the average mortality level (ML) reached 12.3-17.8 per 100,000 of the population (with morbidity being 1,200-1,400 and was essentially higher among the rural population in comparison with the urban population. During these years the highest ML, was registered among children aged 0-2 years (190-50 per 100,000) and, among adults, mainly among women aged 20-29 years (21.4-19.6 per 100,000). During the years when the epidemic of AVH was absent, ML among these groups was essentially lower: 40-20 among children aged 0-2 years and 4-5 among women aged 20-29 years. In 1987 in the Fergana Valley hepatitis E was detected in 72.2% of all examined patients, and in the southern areas of the country in 68.7%. A sharp rise on mortality among women of the productive age at the period of the epidemic rise of AVH morbidity in the endemic region indicated that this epidemic was linked with hepatitis E. High ML among young children may be indicative of a highly unfavorable course of hepatitis E in the group of infants, which had never been registered before. This newly established regularity may be used for the retrospective diagnostics of the outbreak of hepatitis E. 相似文献
20.
Jonathan A. Polonsky Isabel Martínez-Pino Fabienne Nackers Prosper Chonzi Portia Manangazira Michel Van Herp Peter Maes Klaudia Porten Francisco J. Luquero 《PloS one》2014,9(12)