重金属在食用菌中的富集及对其生长代谢的影响

本文报导食用菌对重金属的吸收积累性能及重金属对食用菌生长代谢的影响。从供试的香菇、凤尾菇、金针菇及木耳等食用菌研究表明:对Hg、Pb、As、Ni、Cd、Cu、Zn等重金属均有不同程度的富集作用,其中对Hg的富集是极显著的,但对Pb则不明显。从福建省食用菌生产点采样测定结果看,子实体中的重金属含量均不超标。上述重金属对食用菌生长均有不同程度的不良影响,尤其以Hg和As为突出。对产量影响的顺序以香菇最大、凤尾菇次之、金针菇较弱。重金属在一定范围内对香菇抗坏血酸氧化酶活性有激活作用,对纤维素酶有抑制作用。     

用于绿豆种质资源遗传多样性分析的SSR及STS引物的筛选

目前能够用于绿豆(Vigna radiate)种质资源遗传多样性分析的PCR引物极其有限。通过12份农艺性状差异较大的绿豆种质对绿豆以及小豆(Vigna angularis)、豇豆(Vigna unguiculata)、菜豆(Phaseolus vulgaris)等近缘食用豆中的PCR引物进行筛选,结果表明41对绿豆SSR引物中能够有效扩增的有35对,6对有多态性;28对绿豆STS引物中有23对能够有效扩增,2对有多态性;8对小豆SSR引物能够有效扩增的有6对,但均无多态性;27对豇豆SSR引物能够有效扩增的有17对,1对有多态性;24对菜豆SSR引物能够有效扩增的有9对,1对有多态性。这些多态性引物的获得将有助于中国绿豆种质资源的遗传多样性分析。     

西科麦2028抗条锈性的遗传分析

西科麦2028是地理远缘小麦材料的杂交后代,具有突出的抗条锈病性能。为了解西科麦2028对小麦条锈病的抗性遗传规律,以西科麦2028和铭贤169的杂交群体为研究对象,采用我国目前小麦条锈菌流行小种CYR31、CYR32、CYR33、Su11-4对供试群体进行成株期接种,分析杂交后代的抗病性及分布情况。结果表明:西科麦2028对CYR31的抗病性由3对显性基因控制;对CYR32由2对显性和1对隐性基因控制;对CYR33由1对显性基因控制;对Su11-4由1对显性和1对隐性基因控制。     

不同海拔高度农牧民对气候变化的感知与适应

气候变化已经对西藏地区产生了明显而深刻的影响。农牧民对气候变化的当地影响有较系统的认识。以西藏乃东区为研究对象。调查4个不同海拔梯度上农牧民对气候变化的感知与适应,然后利用气象数据对比农牧民对气候变化的感知,探究海拔高度与农牧民感知及其适应行为的关系,分析影响农牧民对气候变化感知与适应行为的因素。结果如下,研究区增温趋势明显,年降水量自2005年以来明显减少。不同梯度上的农牧民对当地气候变化的相对感知强度存在差异。农牧民对气温和雪覆盖变化的相对感知强度较高且基本随海拔升高而增强,而对雨季、农作物病虫害、新的病虫害变化的相对感知强度则随海拔升高而减弱。农牧民对年降水量的相对感知强度整体较低,但对近年年降水量持续减少记忆较深刻。在全球气候变化背景下,流域的上下两端会遭受较多的气候变化负面影响。农牧民对当地气候变化的感知与其采取的适应行为并不具有同步性。农牧民的受教育程度、经济状况、当地传统文化及其对气候变化的感知强度等因素均会影响农牧民对气候变化适应措施的选择。政府在制定及实施气候政策时应考虑流域内不同海拔高度区域气候变化特征及其影响的差异。     

海南霸王岭油丹所在群落的优势种群种间联结性研究

基于2×2联列表,以X2统计量、Ochiai联结测度指数和多物种关联指数为参数,分析了海南霸王岭油丹所在群落中油丹(Alseodaphne hainanensis)等17个主要种群(物种)的种间联结性特征。结果表明, 17个主要种群(物种)总体水平上表现为不显著的正联结。17个物种组成的136个种对中：当取样面积在100 m2时,有72对表现正关联,63对为负关联,1对无关联。X2检验有2对表现显著正关联,有3对表现显著或极显著负关联。有125个种对的0＜OI＜0.6,仅有9个种对的OI≥0.6, 另有2个种对OI=0;当取样面积为50 m2时,有59对表现正关联,70对为负关联,7对无关联。X2检验有6对表现显著或极显著正关联,有2对表现显著负关联。有129个种对的0＜OI＜0.6,而OI≥0.6的种对没有, 另有7个种对OI=0。不同优势种群下的种间联结性存在一定的差异,而以线枝蒲桃(Syzygium araiocladum)等为优势种群的群落种间联结性较高,群落结构较稳定。     

白菜的EST标记及其对油菜的通用性

根据白菜的表达序列标签,设计了28对引物。在对引物、dNTP、MgCl2的浓度及退火温度等参数进行测试后,建立了合适的PCR反应体系。在此反应体系下,以构建EST的白菜自交系A的DNA为模板,对设计的引物进行了筛选,发现有18对引物能对白菜DNA扩增出产物。用筛选出来的引物分别对17个白菜类品种进行PCR扩增,用琼脂糖凝胶电泳分析其产物的多态性,发现10对引物有多态性,这占了筛选引物的55.6%。为检测白菜EST标记的通用性,进一步利用设计的引物对不同油菜品种的DNA进行PCR扩增。在检测的28对引物中,共有24对引物能扩增出产物,占引物总数的85.7%,显示多态性的引物为18对,占引物总数的64.3%.。在对白菜DNA能扩增出产物的18对引物中,对油菜完全可用,且有13对引物产生多态性。而在那些对白菜未扩增出产物的10对引物中,也有6对能扩增出产物,其中5对显示多态性。文章研究结果证明,通过EST建立分子标记是可行的,而且这种标记对近缘物种是可通用的。     

浅议如何写好教学后记

教学后记是教师在课堂教学结束后对教学活动所作的回顾和总结,它记录的是教学过程中的经验和教训,是教学实践的理性升华。它包括对教材内容的取舍或补充,对课时计划的安排．对教学目标的确立,对教学策略的抉择,对教学重难点的确定,对教学内容的组织,对教学程序的编排,对教学方法的选择,对教学媒体的运用,对教学现象的分析,对典型问题的探讨,对学生学习的设计,对学生反映的思考,对教学效果的检评等等。“教后记”是优化课堂教学、提高教学质量的主渠道,认真、科学地写好教后记,对于提高自己的课堂教学水平,增强自身的教育科研能力,大有裨益。     

长豇豆荚色、籽粒色及生长习性的遗传研究

以性状多样的长豇豆为材料,对其荚色、籽粒色和生长习性进行遗传分析。结果表明：籽粒色的相对性状间均表现1对等位基因差异的遗传,黑籽对红籽为显性,黑籽对白籽、红籽对白籽均为显性,花斑籽对红籽为显性。生长习性由2对等位基因控制,其中蔓生对矮生为显性上位性。荚角因材料不同有的表现为质量性状,且紫荚对浅绿荚为显性、浅绿荚对绿荚为显性、白荚对浅绿荚为显性;有的表现为数量性状,即由多基因控制。     

胶州湾放线菌的分离及其抗病原微生物的活性检测

采用涂布法,从胶州湾海泥样品中分离到224株放线菌菌株,并且从海水样品中分离到32株放线菌菌株。根据形态学特性,菌株被分成了7个组。同时利用杯碟法测定了它们的抗菌活性,其中约7%对金黄色葡萄球菌有活性,11%对八叠球菌有效,10%对大肠杆菌有效,11%对绿脓杆菌有效,2%对白色念珠菌有效,5%对隐球菌有效,6%对绿色产色链霉菌有效和6%对米赫毛霉有效。分离到的22%放线菌对所测定的病原微生物有抗性作用。我们的结果表明胶州湾放线菌能够产生对病原微生物有抗性作用的不同代谢物,这些代谢物可以作为筛选新颖天然产物的独特和丰富的资源。     

负责任旅游的五大误区

在翻译正文之前,我想先提一下英文"Responsible Travel"的意涵。一般翻译"Responsible Travel"是照字面直译,我也不例外,都是翻成"负责任旅游"或"负责任的旅游"。但问题来了、是负什幺责任?安全责任?卫生责任?满意责任?或是对谁负责任?对旅客?对旅客的亲人?对交通工具?对业者?对文化?对旅游地?对在地居民?对旅游资源?我的看法是:对我们赖以生存的环境负责任!也就是对大气层以下的生物圈负责任!是对大地万物负责任!也是对后代子孙负责任!     

Quantitative studies on the polarization optical properties of living cells. I. Microphotometric birefringence detection system

A method of polarization optical analysis is described in which phase retardation attributable to birefringence of a minute area in a microscopic object is determined. The optical system consists of a polarizing microscope with "rectified" strain-free lenses, a photoelectric detector to determine the intensity of the light passing through a minute window located at the image plane of the specimen, and a stage that moves the specimen at appropriate velocities for scanning. The error resulting from any flare of light emerging from outside of the area to be measured is minimized by limiting the illuminated area. The specimen can be observed during the measurement of light intensity by illuminating the whole microscope field at a wavelength different from that of the light used for the measurement. The retardation of the specimen is determined by comparing the specimen and background intensities as functions of the azimuth of a Brace-Koherl compensator. Alternatively, retardation is obtained directly from the light intensity at a fixed compensator angle, using the theory of polarization optics. The basal noise level for the present apparatus is approximately 0.03 nm when measuring birefringence of a 4-micron2 area in 0.1 s, using a X 40, NA 0.65 objective. The noise decreases in inverse proportion to the square root of the area times the duration of measurement.     

The effect of specimen geometry on the mechanical behaviour of trabecular bone specimens.

The effect of specimen geometry on the mechanical behaviour of trabecular bone specimens was studied by non-destructive uniaxial compression to 0.4% strain using cylindrical specimens with different sizes and length-to-diameter ratios, and by comparing cubic and cylindrical specimens with the same cross-sectional area. Both the length and the cross-sectional area of the specimen had a highly significant influence on the mechanical behaviour (p less than 0.0001). Within the actual range of length (2.75-11.0 mm) the normalized stiffness (Young's modulus) was related nearly linearly to the specimen length. This dependency on specimen length is suggested to be caused mainly by structural disintegrity of the trabecular specimens near the surface. The normalized stiffness (Young's modulus) was also positively correlated to the cross-sectional area. This dependency on cross-sectional area is probably due to friction-induced stress inhomogeneity at the platen-specimen interface. A cube with side length 6.5 mm or a cylindrical specimen with 7.5 mm diameter and 6.5 mm length are suggested as standard specimens for comparative studies on trabecular bone mechanics.     

Analyse et modélisation statistique linéaire de la structure osseuse crânienne à partir de données morphométriques et anthropométriques pour la prédiction de paramètres mécaniques

The aim of this study is to establish and quantify the relationship between quasi-static stiffness and anthropometric and morphometric parameters of cranial osseous bones. The purpose is to predict the fracture parameters of cranial bone in crashworthiness situation. Within an experimental protocol, 289 specimens are taken from 17 unembalmed human skulls; the subjects are aged between 53 and 82. The specimen are tested under quasi-static three-points bending tests, at 10 mm/min. Morphometric data are got by analysing specimens’ photography. Values are studied by statistical analysis based on linear methods. Data are resumed by Component Principal Analysis. Groups of specimen, in function of the area of extraction of the specimen, are detected. The relationship between the stiffness and the morphometric parameters of the specimen is studied by using multiple linear regression; the input data are the weight, the density and the curvature indices of each specimen. The regression equation for the frontal and parietal areas is confirmed by residuals study; the relative error between predicted values and observed values is 3 ± 25%. There is no linear regression for the specimen taken from the temporal area of the skull.     

江豚的小肾结构指数和尿浓缩能力

对江豚的六项小肾结构指数的测定发现,黄海沿岸江豚的小肾结构指数明显高于长江江豚的。提示前者具有较高的尿浓缩能力。对尿的分析所获结论相同,反映出二者对所栖水域的不同渗透浓度的适应。     

Trimming Selected Areas of Embedments for Electron Microscopy—Dead Simple

Precision trimming of specific areas of plastic embedments can be accomplished without having to find the specimen detail in the block face itself. The desired area is located in a thick section of the pretrimmed block. The position of the area in the section is evaluated using an ocular micrometer. The block is then mechanically trimmed in the ultramicrotome in such a way that the amount of plastic removed from each of its sides is determined from the magnitude of the knife advance. The procedure can be used in connection with inclined blocks if the microtome head can be rotated behind the specimen orientation arc.     

Effect of specimen size on work-of-fracture measurements

It has been suggested that work-of-fracture, which quantifies the ability of a material to resist fracture, is dependent on specimen size. This experiment compared work-of-fracture, calculated as energy per unit area, for different specimen sizes of Plexiglas, bovine tibial bone and aluminum. Three different geometrically similar cross sections were tested for each material for a total of 54 specimens. Work-of-fracture was measured by loading a notched beam (triangular cross section) in three-point bending at a constant deformation rate. The energy necessary to cause fracture was measured from a load-deformation curve. Specimen fracture area was determined using macrophotography. Atomic absorption spectrophotometry was used to determine weight percent calcium of bone specimens and quantitative light microscopy was used to determine fractional void area. Analysis of variance showed no effect of specimen size on work-of-fracture for aluminum or Plexiglas specimens (p greater than 0.05). A significant difference was found, however, between the large (area = 11.7 +/- 1.9 mm2) and small (area = 3.48 +/- 0.68 mm2) bone specimens and between the medium (area = 5.89 +/- 0.69 mm2) and small (area = 3.48 +/- 0.68 mm2) bone specimens. No correlation was found between work-of-fracture and either calcium content (r2 = 0.128) or fractional void area (r2 = 0.0713). The mean work-of-fracture values found are as follows: aluminum, 59.8 +/- 13.7 kJ m-2; Plexiglas, 0.620 +/- 0.074 kJ m-2; bone (area 5.89 +/- 0.69 mm2-11.7 +/- 1.9 mm2), 9.72 +/- 1.93 kJ m-2 and bone (area 3.48 +/- 0.68 mm2), 5.48 +/- 1.79 kJ m-2.     

An assessment of impact strength of the mandible

In this study, an animal biomechanical study was performed to investigate the absorbed energy and impact strength of the mandible in relation to specimen position. Four regions of mandibles were loaded as complete pieces and gripped by the jaw of an Izod impact tester. All tests were carried out wet using the Izod impact test under two different impact loading directions, lateral and ventral.Absorbed energy and impact strength in kilojoules per square meter of specimen area were determined for each specimen. Under lateral impact loading, the absorbed energy was lowest for the anterior section due to the mental foramen's notch effect. The premolar region demonstrated more absorbed energy per unit area, or impact strength, than any other region. However, due to its small cross-sectional area, the premolar region also absorbs less impact energy.Under ventral impact loading conditions, anterior region absorbed twice as much impact energy than under lateral loading conditions. Premolar region absorbed the same impact energy under both lateral and ventral loading. Interestingly, mandibular angle under ventral loading absorbed five times more impact energy than under lateral loading. This behaviour is considered to be a mechanical adaptation to the actual loading of the mandible in vivo.     

Effects of cross-sectional area on human bite studied with raw carrot and surimi gel

The effects of the cross-sectional area of food samples on bite force with molar teeth were investigated using raw carrots and surimi gels. We evaluated human bite force for food samples with different sizes between the upper and lower molars using a multiple-point sheet sensor and electromyography (EMG). The bite force curve and EMG clearly showed textural characteristics of the carrot and gel. In particular, the first peak in the bite curves corresponded to breaking point in the compression test. With increasing cross-sectional area of both foodstuffs, the bite force and contact area increased and the average stress to which the specimen was subjected (mean stress) tended to decrease, while the stress produced between the teeth and the specimen (active stress) did not change. Chewing rhythm and EMG activities were not greatly influenced by sample size. These findings suggest that higher bite force might cause difficulty in biting food with a larger cross-sectional area.     

A new method for determining cross-sectional shape and area of soft tissues

Assessment of the mechanical properties of soft tissues requires accurate measurement of the cross-sectional area. To date, techniques for determining cross-sectional areas of ligaments and tendons have been less than ideal due to the tissues' complex geometries and the fact that they deform easily under an applied external load. A new procedure has been developed for determining the cross-sectional area by means of an image reconstruction technique based on measurements from collimated laser beams. Using this procedure, the actual shape of the specimen cross-section can also be determined. The results are demonstrated to be highly accurate, and this methodology does not require mechanical contact with the specimen.     

THE INFLUENCE OF SPECIMEN TOPOGRAPHY ON X-RAY MICROANALYSIS ELEMENT MAPPING

The effect of specimen topography on x-ray microanalysis element mapping was studied with an electron microprobe and a scanning electron microscope equipped for x-ray detection. Using the lemma and palea of rice inflorescences as models, we determined that specimen topography can physically limit the detection of x-rays and thus lead to erroneous element mapping data. Any geometrical point on a specimen interfering with a straight line from the point of excitation to the detector will cause an absorptive shadow area on the element map. Electrons impinging on a sample surface cause emissions to occur in all directions. Emissions with sufficient energy (x-rays and backscattered electrons) can strike a topographical point different from the location of the focused electron beam, causing detectable x-ray excitation. This phenomenon will also result in erroneous element map data. Methods of recognition of specimen topographical effects on x-ray microanalysis are discussed.