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用壕沟法和Ｍｉｎｉｒｈｉｚｏｔｒｏｎ法对差巴嘎蒿和小叶锦鸡儿根系形态、分布和生物动态的研究表明，差巴嘎蒿根系大量分布于５－３０厘米的土层中，小叶锦鸡儿根系多分布于２０－８０厘米的土层中，有根瘤，一般土壤发育越好根瘤越多。围栏封育四年以后差巴嘎蒿的生长开始减弱，表现为吸收性根（直径小于１毫米）的分生数量显著少于放牧区。生物季两种植物根系数量的增减受降雨频度和降雨量的影响，与地上部分的物候期关系不明显 相似文献
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采用Field Spec4(美国ASD)的便携式光谱仪对科尔沁5种典型沙丘植被的光谱曲线进行测量,并对其特征进行提取分析。结果表明,1)5种典型沙丘植被黄柳(Salix gordejevii)、冷蒿(Artemisia frigida)、麻黄(Herbal ephedrae)、差巴嘎蒿(Artemisia halodendron)和小叶锦鸡儿(Caragana microphylla)的光谱形态大致相同。根据原始光谱差异和多个光谱特征参数可以区分植被类型。"红边斜率"由高到低依次为冷蒿(0.99%)小叶锦鸡儿(0.68%)黄柳(0.59%)麻黄(0.58%)差巴嘎蒿(0.56%)。2)对差巴嘎蒿不同季节光谱反射率特性进行比较分析得知,随植被生长期推移,差巴嘎蒿呈现出"双峰"和"红移"现象,但该现象并不明显。由于研究区在7月份出现持续干旱,植被缺水严重,导致差巴嘎蒿的"红边位置"在7月6日出现微小浮动,显现两个"红边平台"。3)分析不同覆盖度下差巴嘎蒿的光谱特性,差巴嘎蒿的导数光谱呈现"双峰"特性,且当覆盖度大于40%时,"红边位置"与覆盖度并无直接联系,但"红边斜率"与覆盖度呈正比关系。对不同覆盖度下差巴嘎蒿光谱可见光波段的连续统去除,得到吸收深度随覆盖度的增加而增大,吸收峰面积随覆盖度的增加而减小,对覆盖度敏感性参数比较可知,研究该地区差巴嘎蒿覆盖度变化优先考虑吸收峰面积。因此,基于植被高光谱特性的分析,对于今后利用遥感监测沙丘植被长势、植被分类识别及反演植被覆盖度等的应用提供重要的参考价值。 相似文献
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水分胁迫对冷蒿和差巴嘎蒿溶质累积的影响 总被引：1，自引：0，他引：1
冷蒿干物质累积高于差巴嘎蒿，水分胁迫出现时差值更显著；差巴嘎蒿可溶性蛋白质在土壤含水量为10％时即开始大量分解，冷蒿分解的时间稍后（在土壤含水量7％时）；正常土壤含水量条件下冷蒿硝态氮含量和硝酸还原酶活性高于差巴嘎蒿，极端干旱时两种牧草上述指标均降至很低且数值相近；冷蒿在土壤水分轻度胁迫时脯氨酸大量累积，累积量可达胁迫前的8．2倍，差巴嘎蒿只达原来的2．2倍；缺水使冷蒿可溶性糖大量累积，冷蒿达胁迫前的1．29倍，差巴嘎蒿只达胁迫前的0．37倍。 相似文献
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科尔沁沙地冷蒿和差巴嘎蒿对水分胁迫的反应及差异性 总被引：7，自引：1，他引：6
在土壤正常水分条件下,冷蒿的ΨＷ、Ψπ和Ψπ＾１００远远低于关 嘎蒿,而ＲＷＤ、Ｖａ及Ｖａ／Ｖｓ远远大于差巴嘎蒿,维系其生命活动的膨压只占差巴嘎蒿的３０％。土壤极端干旱时,差巴嘎蒿的上述参数发生大幅度变化,抗旱能力随之提高。极旱的午后,两种灌木均遭旱害威胁,其水分状况参数数值（ΨＷ,Ψ０,Ｖａ和ＲＷＤ）相关很小。旱后复灌的情况下,差巴嘎蒿上述参数同样发生大幅度变化,各参数值可恢复到对照水平;冷蒿在 相似文献
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冷蒿干物质累积高于差巴嘎蒿，水分胁迫出现时差值更显著；差巴嘎蒿可溶性蛋白质在土壤含水量为10%时即开始大量分解，冷蒿分解的时间稍后(在土壤含水量7%时)；正常土壤含水量条件下冷蒿硝态氮含量和硝酸还原酶活性高于差巴嘎蒿，极端干旱时两种牧草上述指标均降至很低且数值相近；冷蒿在土壤水分轻度胁迫时脯氨酸大量累积，累积量可达胁迫前的8.2倍，差巴嘎蒿只达原来的2.2倍；缺水使冷蒿可溶性糖大量累积，冷蒿达胁迫前的1.29倍，差巴嘎蒿只达胁迫前的0.37倍。 相似文献
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齐泰高速公路位于松嫩平原干旱、半干旱地区,耐旱护坡植物的选择对防止公路边坡水土流失,增强路基稳定性及公路周边生态恢复具有重要意义。以紫穗槐(Amorpha fruticosa)、柽柳(Tamarix chinensis)和小叶锦鸡儿(Caragana microphylla)2年龄灌木为试验材料,采用干旱棚控水法,对灌木进行5个水分梯度处理(对照、轻度胁迫、中度胁迫、重度胁迫、极重度胁迫)21 d后,测定灌木叶片的电导率、叶绿素(Chl)总量、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、可溶性糖(SS)含量以及脯氨酸(Pro)含量,探讨3种植物的抗干旱能力。结果表明,随着干旱胁迫的加剧,3种灌木叶片的Pro含量、膜质透性(RPP)呈上升趋势;叶片的Chl总量、SOD活性呈先上升后下降的趋势。紫穗槐和小叶锦鸡儿的叶片MDA含量和SS含量呈先上升后下降的趋势,柽柳叶片MDA和SS含量呈上升趋势。通过隶属度函数得出3种灌木对干旱胁迫适应程度由高至低为紫穗槐>小叶锦鸡儿>柽柳。紫穗槐适宜种植在轻度干旱和极重度干旱边坡,柽柳适宜种植在中度干旱边坡,小叶锦鸡儿适宜种植在重度干旱边坡。 相似文献
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白刺(Nitraria tangutorum)和沙蒿(Artemisia sphaerocephala)是干旱荒漠区分布较广的沙生植物,生境内风沙流发生频次高、强度大,了解风沙流胁迫下白刺和沙蒿的生理响应对认识沙区植物抗风沙流机理具有重要意义.本研究采用风洞模拟试验,以12 m·s-1的风沙流对白刺和沙蒿幼苗进行0(CK)、10、20和30 min的吹袭胁迫,分析吹袭胁迫对叶片膜透性和膜保护系统的影响.结果表明,随风沙流吹袭时间增加,白刺丙二醛(MDA)和可溶性蛋白(SP)含量逐渐下降,膜透性先降后升,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性在10和30 min胁迫下同时增加,过氧化物酶(POD)活性、可溶性糖(SS)和脯氨酸(Pro)含量逐渐上升,起到了共同防止膜脂过氧化作用;沙蒿MDA含量先降后升,SP含量显著降低(P<0.05),CAT活性仅在20 min胁迫下显著增加(P<0.05),膜透性和POD活性逐渐增大,20和30 min胁迫下的Pro含量小幅度增加,在减轻细胞膜受损过程中起重要作用. 相似文献
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在对毛乌素沙地植被类型和状况调查的基础上,选择沙柳、小叶锦鸡儿＋杂类草、沙蒿＋杂类草、芨芨草等四种主要类型的植被为研究对象,通过标杆法测定不同植被下地表的土壤侵蚀或堆积状况,从而探讨不同类型植被的防风固沙效果,为毛乌素沙地利用植被防风固沙提供依据。结果显示,在30%盖度以下时,各种类型植被下均有比较严重的水土流失现象。在植被盖度达到45%以上后,水土流失现象基本消失。各类植被的水土流失盖度临界值分别为：沙柳38%、小叶锦鸡儿＋杂类草37%、沙蒿＋杂类草34%、芨芨草32%。在相同的植被盖度下,不同类型的植被显示了不同的滞留土壤能力。综合地理条件和水分情况考虑,沙蒿＋杂类草植被和小叶锦鸡儿＋杂类草植被更适合于在毛乌素沙地作为防风固沙植被推广。利用植被防风固沙,不仅要达到临界盖度,而且要灌草结合才能达到更好的效果。 相似文献
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内蒙古荒漠草原优势牧草营养价值评价 总被引：3，自引：0，他引：3
通过测定内蒙古荒漠草原26种优势牧草的常规养分含量、纤维组成、两极离体消化率,分析了不同牧草对放牧内蒙古白绒山羊的营养价值,同时应用随意采食量、静能估测模型计算了荒漠草原优势牧草的分级指数（GI值）,对牧草进行了综合评价。结果表明：（1）用营养成分和消化率指标评定,紫花苜蓿和五星蒿的营养价值最高,其次为中间锦鸡儿、圆头藜,最次为驼绒藜;（2）紫花苜蓿、五星蒿、中间锦鸡儿、圆头藜、碱蓬、全叶马兰、蒺藜草、沙打旺、阿尔泰狗娃花9种牧草GI值较高,牛枝子、甘草、猪毛蒿、松叶猪毛菜、软毛虫实、小针茅居中,灰绿藜、冷蒿、中亚狼尾草、针茅、无芒隐子草、西藏锦鸡儿、驼绒藜、黑沙蒿、刺叶柄棘豆、芨芨草、差巴嘎蒿11种牧草的GI值较低。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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Billinghurst RC Brama PA van Weeren PR Knowlton MS McIlwraith CW 《American journal of veterinary research》2004,65(2):143-150
OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis. 相似文献