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1.
本文通过分析实验证明,种植格拉姆柱花草五年和三年的土壤与对照区土壤相比,有机质增加0.782%和0.69%,增幅分别为38.1%和25.9%;速效氮增加18.7PPM和16.3PPM,增幅达37.4%和21.3%;速效磷增加3.65PPM和6.93PPM,增幅为91.25%和176.48%;速效钾增加6.2PPM和4.77PPM,增幅为72.9%和58%;全氮增加0.025%和0.0232%,增幅分别为24.0%和17.87%.土壤内重要营养元素指标均有大幅度增加,种植年限越长,土壤肥力提高越明显。与此同时pH值上升0.34和0.22,酸性降低;土壤容重降低0.3445g/cm3和0.2050g/cm3,土壤变得更为疏松;毛管持水量增加12.59%和12.02%,土壤保水蓄水能力增强。  相似文献   

2.
藏山羊放牧采食量,消化率及能量代谢研究   总被引:1,自引:1,他引:0  
春季对10只高原型藏山羊成年羊研究表明,公、母羊每只日采食干草量(口罩法)分别为 1.1293±0.35kg和0.8859±0. 08kg;排干粪量(全收粪法)分别为 0.03322± 0. 03kg和0.2991±0.05kg;牧草干物质消化率分别为68.54±9.40%和66.64±6.00%;摄入能分别为18.8850±5.89MJ和14.8145±1.27MJ;消化能分别为13.5255±5.77MJ和10.3067±1.11MJ;代谢能分别为 11. 0909±4. 73MJ和 8. 4515±0.91MJ.  相似文献   

3.
HQSAR、CoMFA和CoMSIA用于研究38个黄酮类神经氨酸酶抑制剂(NIs)的定量-结构活性关系(QSAR),控制其抑制神经氨酸酶(NA)的生物活性,为新药设计提供理论依据和参考信息.HQSAR建模获得R^2、Q^2、Rtest^2和Qext^2分别为0.881、0.834、0.918和0.831.基于药效团叠合,进行CoMFA和CoMSIA建模分析,得到模型的R^2、Q^2、Rtext^2和Qext^2分别为0.988和0.978,0.741和0.802,0.697和0.643,0.604和0.580.而且,氢键对活性的贡献最大,其次是疏水、静电和立体因素.HQSAR结果与CoMFA和CoMSIA结果一致.  相似文献   

4.
在50、100和200mmol/l下,研究了NaCI、Na2SO4和Na2CO3对小麦高生长、生物量生长、脯氨酸及Na+,K+含量的影响。NaCI处理使高度下降8.8%~35.4%、而Na2SO4和Na2CO3分别为8.8%~77.9%和53.1%~100.0%。NaCI处理使鲜重和干重分别降低14.3%~42.9%和6.1%~36.7%,而Na2SO4处理分别为14.3%~64.3%和7.2%~58.9%,Na2CO3处理分别为50.0%~74.1%和48.3%~72.8%。在NaCI、Na2SO4和Na2CO3处理下,脯氨酸含量分别增加0.0%~66.7%、0.0%~33.3%和66.7%~100.0%。Na+/K+分别提高2.5~11.9、3.6~114.1和35.1~156.6倍。结果表明:Na2CO3的胁迫比Na2SO4强,而Na2SO4的胁迫影响又比NaCl强  相似文献   

5.
紫球藻胞外多糖抗柯萨奇B3病毒活性   总被引:5,自引:1,他引:4  
采用离子交换凝胶Q Sepharose Fast Flow,以NaCl梯度洗脱,将紫球藻胞外多糖(ESPS)分离成3个组分ESPS0、ESPS1.0和ESPS1.6,分别占粗多糖总量的44.2%(以质量计,下同),20.3%和16.4%.ESPS0中未测出蛋白,ESPS1.0和ESPS1.6的蛋白含量分别为7.8%和7.6%;ESPS0、ESPS1.0和ESPS1.6的硫酸基含量分别为16.3%,11.6%和8.3%.利用体外模型测试了3个组分的抗CVB3病毒的活性.发现ESPS0,ESPS1.0和ESPS1.6抑制CVB3病毒的半数抑制质量浓度分别为2.03,0.51和0.53mg/L,治疗指数IT值分别为61.6,245.1和235.8;在相同条件下,阳性对照药物病毒唑的半数抑制质量浓度和IT值分别为31.25mg/L和16.0.结果表明,3种组分抗CVB3活性均高于病毒唑。  相似文献   

6.
讨论了中亚热带武夷山先峰岭51龄甜槠Castanopsiseyrei(Champ.exBenth.)Tutch.群落的氮、磷元素的累积和循环.测定结果表明:群落现存量中含有的氮、磷总量分别为155.549g/m2和5.535g/m2,其中地上部分别为127.117g/m2和4.463g/m2;地下部分别为28.432g/m2和1.072g/m2.甜槠群落氮、磷元素的生物循环中,年吸收量分别为9.458g/m2.a和0.434g/m2.a,存留量分别为4.488g/m2.a和0.199g/m2.a,归还量分别为4.970g/m2.a和0.235g/m2.a.它们的氮含量均大小磷含量,周转期氮43年,磷40年,氮元素周转比磷元素慢  相似文献   

7.
Fenton试剂处理乳化含油废水   总被引:3,自引:0,他引:3  
实验室研究了用Fenton试剂氧化处理三种表面活性剂(非离子OP,阳离子CTMAB,和阴离子SDS)乳化原油和柴油废水及用非离子型OP表面活性剂乳化机油废水.其COD含量为1273-2248mg/l,油含量为1825-3977mg/1.Fenton试剂氧化的最佳初始pH、终了pH、Fe^2+用量、H2O2用量和氧化时间分别为2.5-4、10、80.4—120.6mg/l、2.12-21.2g/l(30%H2O2)和3.5h.处理后的乳化原油废水COD去除率、油去除率、色度(UV-254)和浊度(A450)去除率分别为94.8—98.0%、99.4-99.9%、95.1—97.9%和99.0-99.9%;处理后乳化柴油废水COD和油去除率分别为93.9-96.2%和99.6-99.7%;OP乳化剂乳化机油废水处理后COD和油去除率分别为98.2%和97.6%.所研究的乳化废水用Fenton试剂处理后均可达到国家一级排放标准.  相似文献   

8.
通过对珠江三角洲地区的植物和土壤进行长期的野外调查,重点寻找自然条件下放射性核素富集植物.结果表明,芒萁(Dicranopteris dichotoma)地上部分镭(^226Ra)和钍(^232Th)的平均含量(比活度)分别为248.4和679.8Bq·kg^-1,变化范围为118.3~565.6和158.3~2272.9Bq·kg^-1,地下部分(根)^226Ra和。^232Th的平均含量分别为157.8和314.3Bq·kg^-1,变化范围为103.8~239.8和149.3~563.6Bq·kg^-1.对应的生物富集系数(bioconcentration factor,BCF)平均值为1.88和2.74,转移系数(translocation factor,TF)平均值为1.57和2.02.芒萁时镭和钍有显著的富集特征,这一发现为研究天然放射性核素在植物中的超富集机理和污染土壤修复提供了一种新的材料.  相似文献   

9.
目的评价奈韦拉平国产胶囊剂和片剂在健康人体的生物等效性。方法24名健康男性志愿者按照随机顺序接受奈韦拉平国产胶囊剂和片剂0.2g,用高效液相色谱法(HPLC)检测奈韦拉平的血浆浓度。结果奈韦拉平国产胶囊剂和片剂的主要药动学参数:Cmax分别为(1.98±0.48)和(2.02±0.58)mg·L^-1,tmax分别为(3.30±0.45)和(3.30±0.47)h,t1/2分别为(46.40±14.10)和(46.02±11.79)h,AUC0-t分别为(110.28±30.86)和(111.98±29.81)mg·h·L^-1,AUC0-∞分别为(126.92±35.82)和(128.85±33.71)mg·h·L^-1,奈韦拉平国产胶囊剂的相对生物利用度为(98.48±10.51)%和(98.50±11.27)%。结论奈韦拉平国产胶囊剂和片剂具有生物等效性。  相似文献   

10.
利用小波变换,结合折叠周期分析方法,对羊八井宇宙线观测站TibetASy阵列1997年11月到1998年6月的实验记录数据进行了周期分析,发现TeV和10TeV宇宙线流强中存在着太阳日和半太阳日周期变化.TeV宇宙线流强1d和0.5d周期变化的信噪比分别为9.8和12.9,其变化幅度分别为0.44-0.26%和0.3±0.18%,最大变化处的相位分别在约0.8(18h)和0.9(11h).10TeV字宙线流强1d和0.5d周期变化的信噪比分别为10.1和12.9,其变化幅度分别约为0.5+0.34%和0.35±0.23%,最大变化处的相位分别在约0.8(18h)和0.9(11h).  相似文献   

11.
钢制储罐现场安装时,无论是正装法施工还是倒装法施工,焊接变形的控制是关键点。本文利用焊接变形的原理,并从焊接大工艺范畴,即切割下料、成型、焊接等工序较系统地论述控制储罐焊接变形的工艺措施。  相似文献   

12.
心理健康是生理健康、心理健康的统一体;心理健康是良好的品德素质的组成部分,是开发智力的重要内在因素,是大学生全面发展的必要条件;论述了开展心理健康教育行之有效的模式。  相似文献   

13.
对聚众犯罪首要分子与主犯关系进行了探讨,指出聚众犯罪的主犯包括聚众共同犯罪中的首要分子和在聚众共同犯罪中起其他主要作用的犯罪分子;提出只有在不以首要分子为构成要件或以首要分子作为构成要件的聚众犯罪,且首要分子不只一人的情况下,聚众犯罪首要分子才是主犯,而以首要分子为构成要件的聚众犯罪,且首要分子只为一人的情况属于单独犯罪,此时并不存在首要分子与主犯的关系问题。  相似文献   

14.
基于无限长预应力弹性地基梁的积 微分方程控制方程, 通过引进新变量将其扩展成微分方程组, 再利用打靶法求解该扩展系统进而得到该问题的数值解. 结果表明: 后屈曲载荷与后屈曲挠度曲线都依赖于梁挠度为零点的正斜率; 而后屈曲波长不随此斜率的增加而变化.  相似文献   

15.
本文讨论了从一个并系到半环再到子代数的扩张过程,得到了M是并系,则是由M所生成的子代数的结果。  相似文献   

16.
Transfer of a beta-turn structure to a new protein context   总被引:11,自引:0,他引:11  
T R Hynes  R A Kautz  M A Goodman  J F Gill  R O Fox 《Nature》1989,339(6219):73-76
Four-residue beta-turns and larger loop structures represent a significant fraction of globular protein surfaces and play an important role in determining the conformation and specificity of enzyme active sites and antibody-combining sites. Turns are an attractive starting point to develop protein design methods, as they involve a small number of consecutive residues, adopt a limited number of defined conformations and are minimally constrained by packing interactions with the remainder of the protein. The ability to substitute one beta-turn geometry for another will extend protein engineering beyond the redecoration of fixed backbone conformations to include local restructuring and the repositioning of surface side chains. To determine the feasibility and to examine the effect of such a structural modification on the fold and thermodynamic stability of a globular protein, we have substituted a five-residue turn sequence from concanavalin A for a type I' beta-turn in staphylococcal nuclease. The resulting hybrid protein is folded and has full nuclease enzymatic activity but reduced thermodynamic stability. The crystal structure of the hybrid protein reveals that the guest turn sequence retains the conformation of the parent concanavalin A structure when substituted in the nuclease host.  相似文献   

17.
地面火炮毁伤目标所需的弹药消耗量是一随机变量。在研究该随机变量的概率特征时,过去的文献通常假设地面火炮的携弹量为无限或为某一固定常数。该文研究用广义离散型随机变量的概率分布表征火炮携弹量的各种可能情况,较为完美地统一出一个共同的表示形式,并导出了计算毁伤目标所需弹药的平均消耗量的公式,且用实例分析了毁伤目标所需弹药的平均消耗量。  相似文献   

18.
Idiotypic networks regulate the immune response to a variety of antigens. Antibodies generated against other antibodies, called anti-idiotypic antibodies, can themselves mimic antigen and elicit a specific immune response. They have been shown to induce delayed-type hypersensitivity (DTH) to model antigens in the mouse. As anti-idiotypic antibodies are thought to be involved in the response to tumour-associated antigens we tested whether injection of monoclonal antibodies derived from mice hyperimmunized to a syngeneic, chemically induced sarcoma could mimic antigen and induce DTH to the sarcoma in naive mice. One of the monoclonal antibodies, 4.72, primed BALB/c mice for DTH to the sarcoma but not for DTH to another sarcoma or to sheep erythrocytes. Antibody 4.72 did not induce DTH in mice of immunoglobulin allotype congeneic strains nor did it bind to the sarcoma cells. As antibodies specific for this sarcoma have not been detected, we do not know whether idiotype on immunoglobulin molecules is recognized by antibody 4.72. However, as the response induced by antibody 4.72 was both antigen-specific and allotype-restricted, analogous to those induced by anti-idiotypic antibodies in other systems, we propose that antibody 4.72 is an anti-idiotypic antibody.  相似文献   

19.
Antibodies to a scrapie prion protein   总被引:1,自引:0,他引:1  
Scrapie is a slow infection of the nervous system which progresses in the absence of any apparent immune response. The recent development of a large-scale purification protocol for scrapie prions made it possible to obtain substantial quantities of electrophoretically purified prion protein (PrP 27-30) and we report here on the successful production of a rabbit antiserum to PrP 27-30. The antiserum reacted with PrP 27-30 and several lower molecular weight proteins as shown by Western blots; it did not react with protein preparations from uninfected brains. Discrete structures in the subependymal region of scrapie-infected hamster brains were stained immunocytochemically. These same structures also stained with Congo red dye and showed green birefringence with polarized light, a characteristic of purified prion rods. This staining pattern suggests that they are amyloid plaques.  相似文献   

20.
遗传算法在试题组卷中的应用   总被引:18,自引:0,他引:18  
运用遗传算法的全局寻优对自动化组卷系统进行了研究,并得到了一个解决适合考方要求的试题模型的实用算法。  相似文献   

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