共查询到20条相似文献，搜索用时 187 毫秒
1.
利用L~*-幂单半群和R~*-幂单半群,给出具有良恰当断面的富足半群的一个对称的织积结构定理.此结论去掉了拟理想这个重要的前提,且比已有结论的形式更简单.其结果是对逆断面和恰当断面中相应结果的丰富和推广,为进一步研究该类半群的结构、性质及刻画其上的同余奠定了坚实的理论基础. 相似文献
2.
研究了E-拟α-预不变型凸函数的性质与应用.首先,给出了E-拟α-预不变凸函数的定义,用例子说明了其存在性,并给出了在条件A与条件B下(半)严格E-拟α-预不变凸函数的等价刻画.其次,提出了E-拟α-预不变凸条件下的一类约束优化问题(NP1),证明了问题(NP1)可行解集、最优解集的E-α-不变凸性,并给出了问题(NP1)局部最优解的性质.最后,讨论了E-α-预不变凸函数的性质,给出了该类函数的等价刻画,获得了不等式约束下E-α-预不变凸多目标规划问题(MOP1)的最优性结果,并举例验证了所得结论的正确性. 相似文献
3.
张佳 《西南大学学报(自然科学版)》2011,33(8)
令M是有限集合,A是M的非空子集,TM是M上的全变换半群.定义FM={f∈TM|f(A)A}显然,FM是TM的子半群.主要刻画了FM的完全正则元和超富足元的性质,同时描述了FM的完全正则性和超富足性的条件. 相似文献
4.
利用矩阵分块和α-对角占优矩阵的性质,给出了一类局部弱α-对角占优矩阵为广义严格对角占优矩阵及其比较阵为非奇异M-矩阵的若干充分条件,拓展了广义严格对角占优矩阵的判定准则. 相似文献
5.
王竹英 《山西农业大学学报(自然科学版)》2010,30(2):173-175
生态系统的持久性,稳定性及概周期解的存在性问题是数学生态学理论中的一个重要研究方向。对于一些三种群食物链系统,给出上述性质的明确判定准则是数学生态学的一个重要课题,受到理论生态学家与数学家的广泛重视。研究食饵种群具有资源利用率的三种群食物链模型。首先,给出系统一致持久的充分条件,利用Brouwer不动点理论证明了系统正周期解的存在性,进一步证明了在适当条件下,系统正周期解的存在唯一性和全局渐近稳定性。 相似文献
6.
某些子群的覆盖-远离性质对有限群结构的影响 总被引：2，自引：0，他引：2
利用覆盖-远离子群的概念研究了群的超可解性和幂零性.首先利用有限群G的Fitting子群和Sylow子群的覆盖-远离性质给出了关于G超可解的几个充分条件;然后再对G的Sylow子群的正规化子等的覆盖-远离性质进行讨论,得到了关于G幂零的几个充要条件和充分条件. 相似文献
7.
研究了共形平坦(α,β)-度量的刚性性质.首先,在β是关于α的共形1-形式且为闭的条件下,证明了共形平坦(α,β)-度量一定是局部Minkowski度量.其次,根据射影Ricci平坦Randers度量的特性,证明了共形平坦且射影Ricci平坦的Randers度量一定是局部Minkowski度量. 相似文献
8.
研究几何突变人口半群的单调性和FRR性质.证明了q-矩阵Q在l∞生成正的压缩半群;在c0空间上生成连续压缩半群;最小Q-函数P(t)是FRR的,并且给出了其为随机单调的判别标准. 相似文献
9.
研究Banach空间X中的抽象半线性泛函微分方程d/dtx(t) = Ax(t)+F(t, x_t(·))的小时滞鲁棒稳定性,其中无界线性算子A在X上生成一个C0-半群T(t)_t≥0, F是非线性函数.在F是全局Lipschitz连续的条件下,利用算子半群理论以及扰动方法,证明了上述方程的解的指数稳定性对小时滞是鲁棒的.Abstract： The robust stability of the abstract semi-linear functional differential equationd/dtx(t)= Ax(t)+F(t, x_t(·))is considered in Banach space X, where the linear operator A generates a C_0-semigroup [T(t)]_t≥0in X, and F is a nonlinear function. Under the condition that F is globally Lipschitz continuous, and the robust stability of the above equation is proved with the operator semi-group theory and perturba-tion method. 相似文献
10.
Brunn-Minkowski不等式是凸几何分析的重要研究内容.目前,关于体积等几何量的Brunn-Minkowski不等式已广为人知,并在数学各个分支中扮演着重要的角色.关于凸体表面积的Brunn-Minkowski不等式作为Aleksandrov-Fenchel不等式的特殊情况也得到确证.但在L_p Brunn-Minkowski理论中,L_p表面积测度的Brunn-Minkowski不等式仍是一个重要的公开问题,不论是对0p1,还是p1的情形,都没有行之有效的方法来证明相关猜测.基于Minkowski加法,利用单调有界定理和积分中值定理研究了平面凸体的α-周长,提出了两凸体关于α-周长的Brunn-Minkowski型不等式,并对两凸体分别为正n边形和单位圆盘的情形给出了证明. 相似文献
11.
Weizhen Lan Guangcun He Chenyi Wang Shijun Wu Rui Qin 《Frontiers of Agriculture in China》2007,1(3):237-242
Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) were applied to somatic chromosome preparations
of Oryza sativa, O. officinalis and O. meyeriana with labeled probes of C
0
t-1 DNA and genomic DNA from cultivated rice. The coverage percentage (%) and size (Mb) of C
0
t-1 DNA in O. sativa, O. officinalis and O. meyeriana were 47.1 ± 0.16, 38.61 ± 0.13, 44.38 ± 0.13 and 212.33 ± 1.21, 269.42 ± 0.89, 532.56 ± 1.68, respectively. The coverage
percentage and size of probe signals with genomic DNA from O. sativa in O. officinalis and O. meyeriana were 91.0%, 93.6% and 634 Mb, 1 123 Mb respectively, in which there were 365 and 591 Mb in O. officinalis and O. meyeriana which came from O. sativa genomic DNA not from repetitive sequences of O. sativa, and the uncovered genome size in O. officinalis and O. meyeriana was 64 and 78 Mb, respectively. In addition, karyotype analysis was conducted based on the signal bands of C
0
t-1 DNA in O. sativa, O. officinalis and O. meyeriana. The results showed that highly and moderately repetitive sequences in Oryza genus were conserved as the functional genes during the evolution process. The repetitive sequence reduplication might be
one of the important causes of genome enlargement in O. officinalis and O. meyeriana; the O. officinalis genome enlarged more slowly compared with O. meyeriana. Based on the above results, it is concluded that O. officinalis and O. meyeriana formed by reduplication, rearrangement and gene selective loss during the evolution process.
Translated from Scientia Agricultura Sinica, 2006, 39(6): 1083–1090 [译自: 中国农业科学] 相似文献
12.
Suriyan Cha-Um Souvanh Thadavong Chalermpol Kirdmanee 《Frontiers of Agriculture in China》2009,3(3):266-273
Osmotic stress is one of the most important abiotic factors which inhibit growth and development in both the vegetative and
reproductive stages of many plant species. The aim of this investigation was to compare the biochemical and physiological
responses in C3 rice and C4 sorghum to water deficit. Chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (TC) and total carotenoid (Cx+c) contents in both rice and sorghum seedlings under osmotic stress were adversely affected, related to increasing osmotic
pressure in the culture media. In addition, the chlorophyll’s fluorescence parameters and net photosynthetic rate (P
n
) decreased, leading to growth reduction. Also, a positive correlation was found between physiological and biochemical data,
while proline accumulation showed a negative relationship. The Chlb, P
n
and fresh weight were maintained better in osmotic-stressed (− 1.205 MPa) C4 sorghum seedlings than those in C3 rice seedlings. The growth and physiological responses of C3 rice and C4 sorghum decreased depending on the plant species, the osmotic pressure in the media and their interactions. Pigment content
and P
n
ability in C4 sorghum grown under mannitol-induced osmotic stress increased to a greater degree than in C3 rice, resulting in maintenance of growth. 相似文献
13.
Jianfu Zhang Swapan K. Datta Guoying Wang Huaan Xie 《Frontiers of Agriculture in China》2007,1(3):243-249
Pyruvate orthophosphate dikinase (PPDK) is a key enzyme in photosynthesis in some plants that exploit the C4 photosynthetic pathway for the fixation of CO2. The C4-specific PPDK encoding pyruvate orthophosphate dikinase was introduced into C3 plant, a rice (Oryza sativa L. cv. indica IR64) mediated by biolistic and Agrobacterium transformation. The C4-PPDK gene of maize was integrated to indica IR64 with polymerase chain reaction (PCR)-Southern blotting. The total nitrogen of flag leaves of transgenic IR64 was analyzed
with Kjeldahl method for quantitative determination of nitrogen, indicating that the total nitrogen of flag leaves of most
transgenic IR64 was higher than that of non-transgenic control IR64 formants in the greenhouse. The maximum value of total
nitrogen of flag leaves was 3.61% among transgenic IR64 plants, 1.07% higher than that of non-transgenic control IR64 formants.
The total nitrogen of flag leaves of transgenic IR64 was increased by 42.1%. The factors for yield of transgenic IR64 plants
were analyzed, indicating there was a greater difference in yield-forming factors among transgenic IR64 plants in the greenhouse,
i.e. dried plant weight, harvested index and so on. Thus, it could help rice breeders select different materials for breeding.
Translated from Molecular Plant Breeding, 2006, 4(6): 797–804 [译自: 分子植物育种] 相似文献
14.
为研究五谷虫蛋白粗提液对Escherichia coli O_1和E.coli O_(78)的体外抑菌作用,采用试剂盒测定五谷虫粗提液蛋白含量;牛津杯法测定蛋白粗提液对牛源病源性E.coli O_1和E.coli O_(78)的抑菌圈直径;通过二倍稀释法测定蛋白粗提液对2种细菌的最低抑菌浓度(MIC);平板法测定最低杀菌浓度(MBC);酶标比浊法测定粗提液对2种细菌的24h生长曲线、细胞膜通透性以及碱性磷酸酶(AKP)的含量。研究表明:1)五谷虫蛋白粗提液蛋白质量浓度为0.680mg/mL;粗提液对E.coli O_1和E.coli O_(78)的抑菌圈直径分别为(25.09±0.62)和(20.96±0.48)mm,MIC分别为15.625和31.250mg/mL,MBC为62.5和125mg/mL,传统中药水煎剂和提取缓冲液没有体外抑菌效果。2)粗提液能影响E.coli O_1和E.coli O_(78)的生长曲线,增加细菌细胞膜和细胞壁通透性。由此可见,蛋白粗提液对E.coli O_1和E.coli O_(78)均有体外抑菌效果,且对E.coli O_1的体外抑菌效果优于E.coli O_(78)。 相似文献
15.
为深入理解富勒烯(Fullerene,nC_(60))的水生生态毒理效应,以模式动物大型蚤(Daphnia magna)为研究对象,研究nC_(60)对大型蚤的48 h和72 h急性毒性效应以及21 d慢性毒性效应。结果表明,急性暴露下,nC_(60)对大型蚤的48 h半抑制浓度(EC_(50))和半致死浓度(LC_(50))分别为25.3 mg·L~(-1)和28.5 mg·L~(-1),72 h的EC_(50)和LC_(50)分别为14.9 mg·L~(-1)和16.3 mg·L~(-1),且大型蚤的跳跃频率和心跳频率随着在nC_(60)中暴露时间的延长先增加后减少;慢性暴露下,1 mg·L~(-1)的nC_(60)即可对大型蚤的繁殖产生影响,21 d内总产蚤数和平均产蚤数分别为53.3个和0.3个,与对照相比明显降低。研究结果表明,无论急性还是慢性暴露下,nC_(60)均显著抑制大型蚤的生长和繁殖,其水生生态毒性不容忽视。 相似文献
16.
锑对土壤中秀丽隐杆线虫的毒性效应 总被引：1，自引：1，他引：0
为明确锑（Sb）对土壤无脊椎动物线虫的毒性效应及不同类型土壤中Sb的毒性差异,以生长量、生育率和繁殖力为评价终点,研究了3种土壤（西安垆土、鹰潭红壤、江门红壤）中外源Sb对模式生物——秀丽隐杆线虫（Caenorhabditis elegans）的毒性效应。结果表明：基于西安垆土、鹰潭红壤、江门红壤的土壤总Sb含量推导得出的Sb对线虫生长毒性的EC50 （半数效应浓度）分别为1 138、2 163、4 074 mg·kg-1,对线虫生育毒性的EC50分别为849、1 472、3 244 mg·kg-1,对线虫繁殖毒性的EC50分别为574、836、1 470 mg·kg-1。通过毒性阈值可知,线虫的评价终点对Sb毒性的敏感性由高到低依次为繁殖、生育、生长。相关性分析表明,阳离子交换量、有机质含量和非晶质铁氧化物含量是影响土壤中Sb毒性的主要因素。基于有效态Sb含量推导得出的3种土壤中Sb的毒性阈值差异缩小,说明有效态Sb含量能够更好地解释不同土壤中Sb毒性的差异。 相似文献
17.
With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (P
n), intercellular CO2 concentrations (C
i), stomatal conductance (G
s), transpiration rate (T
r), apparent quantum yield (Φ
c), and carboxylation efficiency (CE) of cucumber seedlings under hypoxia stress. The results showed that P
n decreased gradually under the hypoxia stress, and reached the minimum 10 days later, which was 63.33% of the control. Compared
with that of the hypoxia-stressed plants, the P
n 10 days after the application of exogenous Spd increased by 1.25 times. A negative correlation (R
2=0.473−0.7118) was found between P
n and C
i, and G
s and T
r changed in wider ranges, which decreased under the hypoxia-stress, but increased under the hypoxia-stress plus exogenous
Spd application. There was a significant positive correlation between G
s and T
r (R
2=0.7821−0.9458), but these two parameters had no significant correlation with P
n. The hypoxia stress induced a decrease of Φ
c and CE by 63.01% and 72.33%, respectively, while the hypoxia stress plus exogenous Spd application made Φ
c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused
by non-stomatal inhibition, while the exogenous Spd alleviating the hypoxia stress by repairing photosynthesis systems.
__________
Translated from Chinese Journal of Applied Ecology, 2006, 17(9): 1609–1612 [译自: 应用生态学报] 相似文献
18.
Na Niu Gaisheng Zhang Yue Cao Yu Zhang Fang Wei 《Frontiers of Agriculture in China》2008,2(4):386-390
A new method for producing a NIAN type wheat maintenance line with the male sterile gene rfv
1
was described. That is the variety Xinong Fp1, a 1BL/1RS translocation line, as the acceptor and Triticum macha var. subletschchumicum, a non-1BL/1RS translocation line, as the donor, a directional substitution backcross was made and confirmed by chromosome
of root tip preparations and SDS-PAGE analysis. The male sterile gene rfv
1
of Triticum macha var. subletschchumicum was transferred to the genome of Xinong Fp1. A new NIAN type wheat maintenance line with the male sterile gene rfv
1
was bred. The method described was successful in breeding a new male sterile type for hybrid wheat production.
__________
Translated from Journal of Triticeae Crops, 2008, 28(1): 21–24 [译自: 麦类作物学报] 相似文献
19.
为探究回乳期奶牛血清中促乳素(PRL)、雌二醇(E2)、孕酮(P4)、信号转导和转录激活因子5(STAT5)含量和产奶量变化规律及其相关性,选择规模化奶牛场产奶量为(15.43±0.60)kg,将干乳的妊娠后期奶牛20头为研究对象。干乳开始当天记为第0天,分别在第0、1、3、5、7、9和11天上午8:00采集奶牛尾静脉血,ELISA法检测血清中PRL、E2、P4和STAT5含量并对结果进行统计学处理,分析其在奶牛回乳过程中的变化规律及其相关性。结果表明:回乳期奶牛血清PRL含量和产奶量在0~1d变化不显著(P0.05),3~11d依次降低且差异极显著(P0.01);血清E2含量0~1d、3~5、7~9d、9~11d之间差异均不显著(P0.05),依次呈阶梯式下降趋势;血清STAT5含量同样呈下降趋势,回乳0~5d、7~11d差异不显著(P0.05),但0~5d与7~11d两阶段间差异极显著(P0.01);血清P4含量从回乳0~11d变化不显著(P0.05);回乳期奶牛产奶量与PRL、E2、STAT5含量呈极显著正相关(P0.01),PRL、E2和STAT5含量变化两两间均呈极显著正相关(P0.01);P4含量变化与PRL、E2、STAT5含量和产奶量变化的相关性均不显著(P0.05)。综上所述,在奶牛回乳期间,血清中PRL、E2和STAT5含量均呈降低趋势并显著正相关,而P4含量变化不显著且与其他激素无显著相关性,为进一步研究泌乳相关激素调控奶牛回乳的作用机理提供理论依据。 相似文献
20.
尿素和生物质炭对茶园土壤pH值及CO2和CH4排放的影响 总被引：3，自引：0，他引：3
为明确生物质炭对酸化茶园土壤改良及温室气体排放的影响,利用室内培养试验,研究了在施氮(N1)和不施氮(N0)条件下,不同小麦秸秆生物质炭添加量(B1,10 g·kg~(-1);B2,30 g·kg~(-1);B3,50 g·kg~(-1))对茶园土壤pH值、CO_2和CH_4排放的影响。结果表明,添加生物质炭显著提高了茶园土壤pH值(P0.05),生物质炭施加比例越高,土壤pH值提高幅度越大,处理组N0B1、N0B2和N0B3土壤平均pH较对照组CK(氮和生物质炭都不施)分别提高了0.18、0.53、1.06个单位,生物质炭添加量为3%(B2)时,短期内可达到提高土壤pH值、改良酸化土壤的效果;CO_2和CH_4的累积排放量随着生物质炭添加比例的升高而增大,且显著高于对照组CK(P0.05)。施加尿素短期内显著提高了土壤pH值(P0.05),并促进了CO_2的排放,但对CH_4的排放无显著影响。与单施生物质炭相比,生物质炭与尿素共施时土壤pH提高幅度更大,CO_2累积排放量提高程度也更为显著,而CH_4的排放得到抑制,但仍显著高于对照组CK(P0.05)。生物质炭的添加在提高土壤pH值的同时也会增加CO_2和CH_4的排放量,增大环境风险,但当土壤酸化程度较轻时,可适当施加低量生物质炭,在缓解土壤酸化状况的同时尽可能地减少温室气体的排放量。 相似文献