600 MPa高强钢筋与混凝土的粘结锚固性能试验研究

为研究600 MPa高强钢筋与混凝土粘结锚固性能,设计了72个棱柱体试件进行拉拔试验,对600 MPa高强钢筋粘结锚固的破坏形态及粘结应力分布进行分析,通过建立基本粘结滑移关系及位置函数,确定600 MPa高强钢筋在混凝土结构中的粘结滑移本构关系。采用一次二阶矩法进行可靠度分析,提出锚固长度设计建议。研究表明：600 MPa高强钢筋粘结锚固的破坏形态及粘结应力分布与普通钢筋类似且粘结锚固性能良好,《混凝土结构设计规范》（GB 50010—2010）基本锚固长度计算公式依然适用于600 MPa高强钢筋。     

软岩地质条件下浅埋隧道锚缩尺模型试验

为研究隧道锚的受力变形和锚碇承载特性等问题,在重庆几江长江大桥工程北岸现场开展1∶30缩尺模型试验。试验结果表明：从相似设计荷载240 kN到1 680 kN,双锚碇前锚面沿拉拔方向的最大位移平均值为0.020~0.808 mm,双锚碇前端上部地表岩体铅直方向的最大位移值为0.028~0.749 mm,双锚碇后端上部地表岩体铅直方向的最大位移值为0.014~0.645 mm;锚碇围岩破裂类型是拉剪复合型破坏;锚碇上方地表横桥方向参与抗拔作用的岩体范围约2~3 m,而沿锚碇轴向参与拉拔作用的岩体破坏区类似一个倒塞体形状;通过试验得到模型锚的可靠抗拉拔承载能力为1 344 kN;模型锚在840 kN下的流变趋于稳定,其长期安全系数为3.5。模型试验结果表明软岩地质条件下浅埋隧道锚具有较高的抗拉拔承载能力,证明此设计方案是可行的。     

表层嵌贴预应力CFRP板条加固钢筋混凝土梁的应力传递行为

表层嵌贴预应力FRP板条加固钢筋混凝土结构技术可充分发挥FRP材料强度,且不需设置永久锚具,具有较大的潜力。以试验得到的嵌贴FRP混凝土粘结滑移关系为基础,建立了嵌贴预应力CFRP板条与混凝土的粘结应力微分方程,并根据边界条件推导了方程的解析解,得到了嵌贴预应力CFRP板条放张后界面粘结应力、CFRP拉伸应力的分析模型。与试验结果的比较表明,该模型得出的界面粘结应力及CFRP拉伸应力与试验结果吻合较好。在此基础上,考虑放张后CFRP混凝土界面不出现剥离的条件,分析了粘结界面能抵抗的最大容许预应力。     

油菜油体钙蛋白基因BnClo1的克隆和表达

应用同源序列克隆法设计同源简并引物,结合RT-PCR和RACE-PCR技术从甘蓝型油菜中分离克隆了编码28.1 kD油体钙蛋白( caleosin)的基因BnClo1。其全长1 058 bp的BnClo1 mRNA( GenBank中序列号为AY966447)包含完整的开放阅读框和3＇末端Poly( A)尾巴结构,染色体DNA结构上含6个外显子和5个内含子。Northern杂交结果表明油菜中BnClo1在种子形成中期开始丰富表达,在种子形成后期,即种子开始脱水成熟时期,高量稳定地表达。半定量PCR结果显示BnClo1在油菜种子吸水膨胀后前2 d的茎中明显表达。证明在油菜种子发育期间,BnClo1对mRNA的转录表达是由胚胎发育来调控的,具有显著的时空特性,并与油体的形成和积累密切有关。推测的caleosin蛋白为245个氨基酸残基( GenBank中序列号为AAY40837)组成的两性蛋白质,主要含3个结构域即由N末端1~16位氨基酸残基组成的α-螺旋和17~61位氨基酸残基组成的强亲水性的随机卷曲构成的N-末端亲水性结构域;由80~120位氨基酸残基组成的中间疏水性结构域和C-末端亲水性结构域。N-末端亲水性结构域包含一个潜在的结合Ca²⁺的EF-手结构。中间疏水性结构域包含一个潜在的脯氨酸-结( Proline-Knot)模体,在92~114位氨基酸残基组成的α-螺旋跨膜区域,推测在caleosin蛋白与单层磷脂层和油体锚定结合上及增加种子油体的稳定性上起着重要的作用。     

变流量冷冻水系统温差控制法的适用性

研究了末端设置通断控制阀的一次泵变流量系统在温差控制下的水力特性,并结合风机盘管与房间的非线性换热耦合特性,进一步探讨了温差控制的适用条件以及变温差控制温差值的设定方法。结果表明：末端设置通断控制阀的系统,当管网整体负荷分布均匀且各开启用户的负荷变化规律相近时,温差控制同样是较为适用的,此时系统的水力失调对室内温湿度的影响较小;采用变温差控制时,仅以不同的总负荷率分段设置温差值,并不能获得良好的室内温湿度控制效果,建议以优先保证风盘除湿能力和室内干球温度为原则设定温差值,相比于目前的方法,在同等的室内相对湿度波动下,室内温度的稳定性可以得到保证。     

长期施肥下不同有机质含量农田黑土水稳性团聚体中氮、磷的分布特征

研究长期施肥对不同有机质含量农田黑土水稳性团聚体分级特征、不同粒级团聚体中全氮、全磷含量分布及相关性的影响,为阐明施肥对黑土肥力演变的影响机制提供理论依据。利用中国科学院海伦生态实验站空间移位长期定位试验,研究2种施肥方式下5种不同有机质含量的农田黑土不同粒级水稳性团聚体、水稳性团聚体中全氮、全磷分布特征。结果表明：长期施用化肥对2~1 mm粒级大团聚体含量影响最大,施肥处理在该粒级团聚体分别增加了1.95%~4.59%之间,且各粒级水稳性团聚体随土壤有机质含量的增加而呈递增的趋势。不同农田黑土全氮、全磷在2~1 mm粒级大团聚体中含量最高,在>5 mm和<0.25 mm含量最低。2~0.5 mm土壤团聚体含量与土壤全氮、全磷存在显著的正相关关系,>5 mm和<0.25 mm与土壤全氮、全磷存在显著负相关关系。土壤全氮、全磷主要存在水稳性大团聚体中,施用化肥可提高水稳性大团聚体中全氮、全磷的含量,是改善农田黑土土壤结构,提高土壤肥力的有效措施。     

采用块体-界面体系的砌体结构简化细观模型

基于ABAQUS装配式建模构架,提出了一种砌体结构的简化细观模型。该建模方法将块体砂浆界面及砂浆层统一采用块体间的界面来代替。界面属性包括法向和切向的力学参数,用来模拟砌体的剪压及受拉行为。界面的法向受拉采用粘性力学参数赋值,并通过与轴心受拉本构模型的等效,推导得出控制界面损伤演化速率的无量纲指数α的计算方程。剪压复合受力模型基于剪摩理论建立,通过粘性属性和库伦摩擦赋值。当剪压复合受力构件处于高轴压比时,通过块体的非线性属性实现了主压应力为主控的损伤阀值。按照该方法进行剪压相关性和砖墙剪切失效的试验仿真模拟,模拟得出的失效形态及力-位移曲线与试验结果基本相符。     

3种小麦DHAR蛋白高级结构建模与功能分析

为揭示小麦脱氢抗坏血酸还原酶(dehydroascorbate reductase,DHAR)的序列特征与其结构和功能的关系,利用DNAman软件比较了小麦3个DHAR基因(Ta DHAR1/2/3)和蛋白质序列特性,利用生物信息软件对蛋白质结构域、亚细胞定位、谷胱甘肽结合位点、N-末端结构域和C-末端结构域界面残基和二级结构进行了预测,并对蛋白质三级结构、表面电位和可及性的空间分布进行了模建和比较。结果表明,小麦Ta DHAR1和Ta DHAR2蛋白质序列长度一致,均定位于细胞质中,仅存在2个氨基酸残基差异,具有完全一致的保守结构域和三级结构;Ta DHAR3定位于线粒体中,与前2者在核酸与蛋白质序列上差异较大,但其保守域、谷胱甘肽结合位点氨基酸残基、假定的N-末端结构域界面残基和C末端结构域界面残基与前2者几乎完全一致,因此,3者可能执行相同的功能。模建的Ta DHAR1/2/3的三级结构均符合立体化学品质规则,其中Ta DHAR1/2的N端形成βαβαββα结构,Ta DHAR3的N端可能形成αββαβαβββ结构,3者在C端均形成β束结构,属于α+β球形蛋白。Ta DHAR1/2蛋白质的空间结构表面基本呈现负电分布,同时也分布着一些较小的正电集团,而Ta DHAR3蛋白质的空间结构表面整体上为均匀负电分布,基本不存在正电,3种小麦DHAR蛋白质表面的氨基酸残基可及性较强,内部可及性相对较弱。本研究有助于理解小麦DHAR蛋白的功能。     

超高效液相色谱-串联质谱法测定甜菜中除草剂残留含量

为了建立甜菜中3种除草剂的定量分析方法,采用超高效液相色谱-电喷雾串联四极杆质谱仪,在多反应监测正负离子扫描模式下对样品进行添加回收率试验。样品经甲醇配合快速溶剂萃取仪提取后配合固相萃取前处理小柱,甲醇、丙酮、二氯甲烷各2 m L为洗脱溶剂净化,外标法定量。结果表明:加标水平分别为50、20、10μg/kg时,回收率为65.81%~100.36%,相对标准偏差(RSD)为1.4%~6.55%,方法的定量限在0.6~2.5μg/kg之间,该方法具有快速、简便、灵敏度较高的特点,能同时满足甜菜中3种农药残留分析的要求。     

再生混凝土与锈蚀钢筋间的粘结性能试验研究

为了探究再生混凝土结构的耐久性能,对5组不同钢筋锈蚀率(0~9%)的再生混凝土梁式试件进行加载试验。分析不同钢筋锈蚀率对再生混凝土梁式试件的钢筋应变、局部粘结应力、粘结滑移和极限粘结应力的影响。结果表明：钢筋锈蚀率大于3%时试件底部开始有细微锈胀裂缝出现;锈蚀率越大,荷载作用下钢筋应变沿锚固位置的变化曲线越平缓;局部粘结应力沿锚固段呈现出双峰分布,峰值主要集中在加载端和自由端附近;加载端附近位置滑移现象最先发生,远离加载端滑移现象延后;随着钢筋锈蚀率的增大,极限粘结强度先增加后降低,极限荷载下的滑移值增大。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Evolution under domestication involving disturbance of genic balance

Summary An hypothesis is developed that the rapid change from wild plants into domesticated crops principally involves the selection of alleles with non-functional gene products which leads to reduced control of the highly integrated metabolism and morphogenesis previously accumulated by lengthy natural selection. Such disturbance of the genome produces altered physiological and morphological development which, although deleterious in nature, serves mankind better and has been selected.     

Genetic variation for disease and nematode resistances and forage quality in perennial diploid and tetraploid lucerne populations (Medicago sativa L.)

Summary Twenty-five lucerne populations of the Medicago sativa complex, which were either diploid or tetraploid and wild or cultivated, were analysed for their resistance to four different fungal diseases and to stem nematode. Forage quality, including stem digestibility and saponin content, was also tested.Populations varied in susceptibility to the diseases caused by Colletotrichum trifolii, Verticillium albo-atrum, Sclerotinia trifoliorum and Pseudopezizza medicaginis, and to the nematode Ditylenchus dipsaci. Except for Sclerotinia rot, sativa and falcata subspecies differed in susceptibility, but this grouping of populations did not account for the full range of variation among them. However, the resistance to P. medicaginis was much lower in the sativa than in the falcata populations.Populations also varied significantly in stem fiber content and digestibility. Stem digestibility was negatively correlated to forage yield. Wild sativa and falcata populations had lower fiber content and higher digestibility than cultivated sativa populations. The medicagenic acid was the sapogenin responsible for the anti-nutritional effect of the lucerne measured by the yellow mealworm larvae Tenebrio molitor. The medicagenic acid content was lowest for the pure sativa populations, highest for the pure falcata populations, and intermediate for the French sativa varieties that have some traits originating from falcata germplasm. Some populations could be used in breeding programs to improve disease and nematode resistance, and forage quality.     

Review of Effects of Active Components of Gastrodiae Rhizoma on Central Nervous System

In order to explore the pharmacological effects of active components of Gastrodiae Rhizoma on the central nervous system,through consulting related literatures,...     

Effects of Pb on Rhizosphere Soil Enzyme Activity and Chemical Constituents of Achyranthes bidentata Blume

[Objectives]The purpose of this study was to investigate the effects of Pb on rhizosphere soil enzyme activity and chemical constituents of Achyranthes bidentat...     

不同P-Zn配比对小麦幼苗微量元素营养的影响

采用了螯合-缓冲营养液培养方法对小麦进行了苗期培养试验,在3个P水平(0,0.6,3.0 mmol/L)和3个Zn水平(0,3,30 μmol/L)的完全组合下对小麦苗期生长及Zn、Fe、Cu、Mn营养进行了研究,旨在为小麦微肥施用提供理论依据.结果表明,P、Zn的正常供应促进了小麦生长,二者的缺乏与过量均会抑制小麦发育,且这种影响在冠部表现得更为明显.在小麦苗期,Zn与Cu的吸收存在明显的拮抗作用,但供Zn则促进了Zn和Cu的转运,而Mn转运则受到了抑制;过量供Zn时,大量Zn被转运到冠部,同时明显抑制了(Fe+Cu+Mn)的吸收总量;P的供应显著地抑制了Fe的吸收,但P的供应提高了Zn、Cu、Mn的转运率;P、Zn在对Zn与Fe、Cu、Mn间吸收竞争的影响中,Zn本身的影响要比P的影响更为明显,供Zn明显促进了小麦幼苗对Zn的吸收;在小麦幼苗冠部,Zn与Fe的竞争中,供P利于Zn的吸收,缺P则利于Fe的吸收;而Zn与Cu以及Zn与Mn间的竞争中,缺磷时利于Zn的吸收,供磷后则利于Cu和Mn的吸收.总之,小麦幼苗Zn、Fe、Cu、Mn营养中,P、Zn的不同配比会不同程度地改变Zn与Fe、Cu、Mn的协同或拮抗效应.     

Isozyme variation between diploid and tetraploid cytotypes of Glycine tabacina (Labill.) Benth.

Summary Glycine tabacina (Labill.) Benth. is a wild perennial species related to the cultivated soybean, G. max (L.) Merr. It is composed of diploid (2n=40) and tetraploid (2n=80) cytotypes. Currently, to differentiate the cytotypes, plants are grown out in the greenhouse and chromosome counts made on pollen mother cells. It is a laborious and time consuming process. The objective of this study was to determine whether electrophoretic techniques could be utilized to separate the cytotypes. Electrophoretic examination of seven isozyme systems from seed of 67 G. tabacina accessions revealed banding patterns that could be used to differentiate between diploid and tetraploid cytotypes in the species. Among the tetraploid accessions, the number of bands observed were always greater than the diploids. Some tetraploid banding patterns consisted of bands similar to the diploid tabacina and/or additional bands previously identified in other Glycine species. The patterns of isozyme multiplicity and variation in the tetraploid tabacinas suggests more than one mode of origin for the tetraploids.     

Some physiological and photosynthetic characters of rice × sorghum and rice × wheat hybrids

Summary Some photosynthetic characters as-leaf anatomy, leaf photosynthetic rate and CO₂ compensation pointdistinguishing C₃ and C₄ plants and physiological characters as leaf area ratio, nitrogen content, leaf stem ratio and total shoot-to-root and deep root-to-shoot ratios have been studied in rice × sorghum and rice × wheat hybrids. Rice × sorghum 1. has lower values of photosynthetic rate, leaf nitrogen, total root and deep root-to-shoot ratio and CO₂ compensation point as of rice parent where as, rice × sorghym 2. is superior in all these characters. Both hybrids lack kranz anatomy. Though both rice × sorghum hybrids show characters of C₃ rice plant but rice × sorghum 2. has improved drought tolerance and leaf characters in relation to yield. Rice × wheat hybrid have higher assimilatory area and higher total root-to-shoot ratio. Grains of rice × wheat hybrids are identical to rice grain. However, as grains of rice × wheat hybrid does not contain seed coat, it could be exploited as novel rice germplasm after improvement.Abbreviations T CO₂ compensation point - T21 CO₂ compensation point at 21% O₂ - T2 CO₂ compensation point at 2% O₂ - dR/sR deep Root-to-shoot Ratio - LAR Leaf Area Ratio - CER photosynthetic rate - TR/SR Total Root-to-Shoot Ratio