黄土丘陵区撂荒群落土壤速效养分空间变异性研究

采用经典统计学与地统计学相结合的方法,对黄土丘陵区5块不同撂荒年限样地速效养分在群落尺度上的空间分布特征进行了分析,结果表明,1)与黄土高原地区整体养分水平相比,撂荒样地土壤养分贫瘠,0～20和20～40 cm土层速效养分含量在群落演替中期较高,并且0～20 cm养分含量明显高于20～40 cm;2)速效养分的空间变异主要为结构性变异,撂荒6～7年样地土壤表层的速效钾和硝态氮以及撂荒25年样地20～40 cm硝态氮具有中等空间相关性,其他撂荒群落土壤0～20和20～40 cm的速效养分均具有高度空间相关性;3)随植被群落撂荒演替年限的增加,0～20 cm土层速效钾和硝态氮空间变异性在群落演替前期样地中最大,20～40 cm土层速效钾和硝态氮空间变异性分别在群落演替中期和前、中期样地中最大。0～20 cm土层速效磷和铵态氮空间变异性在群落演替中期样地中最大,20～40 cm土层速效磷和铵态氮空间变异性分别在群落演替前期和中期样地中最大。在不同撂荒年限样地中,4种速效养分具有不同空间自相关性和空间变异性,说明控制这几种养分空间分布的生态学主导过程可能有差异。     

不同恢复年限对柠条林地土壤养分含量和酶活性的影响

【目的】探明不同恢复年限对沙化区柠条林地土壤养分和酶活性的影响。【方法】以甘肃省环县甜水镇3、7、15、21 a的人工柠条（Caragana korshinskii）林地以及沙荒地为研究对象，分别采集0～20、20～40、40～60 cm层土样，测定分析不同恢复年限、不同土层土壤养分指标和酶活性之间的变化规律及差异性。【结果】（1）土壤中的有机碳、全氮、硝态氮、铵态氮、速效磷、速效钾含量和过氧化氢酶、蔗糖酶、脲酶、碱性磷酸酶的活性随着恢复年限的增加呈增加趋势，pH值随恢复年限增加逐渐减小；（2）沙荒地中，土壤养分含量和酶活性在0～20 cm土层最低，在0～40 cm土层中显著低于林地，柠条林地内土壤养分含量和酶活性随着土层深度的增加表现出明显的“表聚”现象；（3）相关分析表明，土壤中的有机碳、全氮、速效氮、速效磷、速效钾含量、过氧化氢酶、蔗糖酶、脲酶、碱性磷酸酶活性之间彼此均呈极显著正相关（P<0.01），与pH值呈极显著负相关（P<0.01）。【结论】不同年限的柠条林对0～20 cm土壤养分含量和酶活性的影响最为明显。。     

高原鼠兔洞口密度对高山嵩草草甸土壤主要养分含量的影响

高原鼠兔(Ochotona curzoniae)干扰会引起高山嵩草(Kobresia pygmaea)草甸土壤养分含量的变化。本研究分析了高原鼠兔干扰对高山嵩草草甸土壤主要养分的影响,并同步分析了高原鼠兔有效洞口密度和总洞口密度与土壤主要养分含量的关系。结果表明,高原鼠兔干扰显著增加了土壤0-20cm土层有机碳、全氮、全磷、铵态氮、硝态氮含量(P0.01),但显著降低了土壤速效磷含量;随着高原鼠兔有效洞口密度和总洞口密度增加,土壤0-20cm土层全效养分(有机碳、全氮、全磷)含量先增加后降低,而速效养分(铵态氮、硝态氮、速效磷)含量先降低后增加,说明高原鼠兔总洞口密度和有效洞口密度与土壤养分含量的关系一致,因此当分析高原鼠兔干扰程度对土壤养分含量影响的趋势时,可采用总洞口密度代替有效洞口密度。     

围封对黄土高原草地土壤铵态氮和硝态氮的影响

本研究以黄土高原长期放牧草地和围封7年的草地为对象,分析了土壤铵态氮和硝态氮含量的季节变化,并应用RDA冗余分析法分析了土壤水分、植被地上绿色生物量以及土壤微生物生物量碳对土壤铵态氮、硝态氮的影响。结果表明,铵态氮是围封与放牧草地土壤有效氮的主要组分;两样地0-10cm土层土壤铵态氮与硝态氮均主要受植被地上绿色生物量的影响;围封草地10-20cm土层土壤硝态氮主要受土壤水分与植被地上绿色生物量的共同影响,而放牧草地10-20cm土壤铵态氮和硝态氮主要受植被地上绿色生物量的影响;土壤铵态氮与硝态氮之间呈极显著正相关(P0.01);放牧草地围封7年后,较高的生物量使得凋落物及土壤有机质增加;另外,围封后土壤水分在多数季节显著增加(P0.05),这些因素共同促进了土壤氮素的矿化。     

尕海湿地退化演替过程中土壤氮组分的变化特征

为了研究尕海沼泽化草甸湿地随退化程度的加剧氮素的分布特征,对该区域4个退化演替阶段,即未退化(UD)、轻度退化(LD)、中度退化(MD)和重度退化(HD)的4个土层深度(0～10 cm、10～20 cm、20～30cm和30～40 cm)土壤的全氮、速效氮、微生物量氮及亚硝态氮含量进行了测定.结果表明:不同阶段0～40 cm土层全氮、亚硝态氮、微生物量氮和速效氮含量均值均按照UD、LD、MD、HD的顺序降低.0～10 cm和30～40 cm土层HD的全氮、速效氮含量分别显著低于UD 15.28％ 和2.33％、12.13％ 和8.41％;UD的微生物量氮和亚硝态氮含量分别显著高出HD 13.94％ 和10.58％、22.69％ 和51.70％(P<0.05).回归分析土壤氮素含量与土层深度之间呈线性负相关关系,除全氮外,其他氮组分含量与土层深度的R2均大于0.88.由此说明湿地退化显著降低了0～10 cm土层湿地土壤的氮素含量,但这种降低趋势随着土层加深逐渐趋于稳定.     

放牧强度对荒漠草原无芒隐子草斑块碳氮化学计量特征的影响

以短花针茅荒漠草原无芒隐子草斑块为研究对象,研究植被-土壤的化学计量特征,探索无芒隐子草斑块在不同放牧强度的干扰下,植物—土壤碳氮的变化规律。研究结果表明:随着放牧强度的增加,无芒隐子草叶片全碳含量、C/N值均显著降低(P0.05);但无芒隐子草根系碳氮含量未发生变化;随着放牧强度的增加,0～30cm根际土壤全碳和全氮含量先增加后降低,30～40cm土层逐渐下降(P0.05),非根际土壤0～30cm全碳和全氮逐渐增加,30～40cm土层全碳先降低后增加,全氮整体呈下降趋势;根际和非根际土硝态氮含量随着放牧强度的增加呈显著增加趋势(P0.05),铵态氮无一致的变化规律;植被-土壤碳氮含量之间无显著的相关关系。     

高寒生态脆弱区不同扰动生境草地植被及土壤无机氮变化特征

为了解不同干扰生境下高寒生态脆弱区草地植被、土壤无机氮素含量变化特征,以天祝高寒草地为对象,选取3种干扰生境(围栏内天然草地、围栏外天然草地以及牧道),测定和分析不同季节、不同土壤深度铵态氮和硝态氮含量变化特征。结果表明,不同干扰生境,地上植物种类、盖度、高度及生物量等变化明显;相同土层深度,铵态氮、硝态氮含量表现为围栏内>围栏外>牧道。相同干扰生境土壤铵态氮、硝态氮含量随土层深度增加而降低,且变化幅度较大,0~10 cm与20~30 cm土层间差异显著;土壤铵态氮、硝态氮含量从4月到10月呈现先增加后减少的趋势,并在8月出现峰值,围栏内土壤铵态氮含量8月与10月无显著差异,围栏外土壤硝态氮含量10月升高。3种干扰生境下铵态氮、硝态氮同地上生物量之间均呈正相关关系。     

黔西北不同土地利用类型下土壤全氮及硝态氮的分布与残留

在黔西北关门山小流域选取5种不同的土地利用类型,通过对其土壤样品进行化学分析,研究不同土地利用类型下土壤全氮及硝态氮的分布特征。结果表明：灌木林地表层土壤全氮和硝态氮含量高于乔木林地。乔木林地和灌木林地坡中和坡脚土壤剖面上的全氮明显高于坡顶。灌木林地的坡顶、坡中和坡脚土壤硝态氮随着深度的增加而降低,乔木林的坡顶和坡中土壤硝态氮在60~80 cm土层处出现累积,但坡脚没有;5种土地利用类型中,土壤全氮含量均以0~20 cm土层最高,随着土壤深度增加迅速降低。灌木林地、玉米地和撂荒地土壤的硝态氮随着土壤深度的增加而降低,但乔木林地硝态氮在60~80 cm土层累积,果园硝态氮在20~40 cm和60~80 cm土层累积;80 cm厚土体中残留的土壤全氮和硝态氮以果园最高,分别为12.18×10³和352.0 kg·hm^-2,不同土地利用类型间土壤全氮残留量差异不显著,但是果园和玉米地的硝态氮残留量显著高于其他土地利用类型。     

模拟降水对短花针茅荒漠草原土壤养分的影响

为了探究降水对短花针茅荒漠草原土壤养分的影响,在内蒙古四子王旗荒漠草原采用完全随机区组设计开展了模拟降水试验,试验设4个不同模拟降水梯度(减少自然降水50%、自然降水、增加自然降水50%和增加自然降水100%),在不同水分梯度下用直径3.5cm土钻钻取表层土样,测定土壤养分(全碳、全氮、全钾、全磷、有机碳、铵态氮、硝态氮、速效钾和速效磷)含量。结果表明:随着降水量的增加,土壤有机碳、全碳、全氮和硝态氮的含量呈显著降低趋势(P<0.05);减少降水能够使土壤养分积累;过高的降水量会导致土壤养分淋溶,造成养分流失;降水处理对土壤钾元素和磷元素含量没有显著性影响。     

荒漠草原区不同植被恢复模式下土壤可溶性氮组分特征

以未平茬人工中间锦鸡儿林地、平茬人工中间锦鸡儿林地、天然草地和天然中间锦鸡儿林地为对象,分别测定各类样地0～5cm、5～10cm、10～20cm及20～40cm土层可溶性氮组分含量并分析其含量特征、垂直分布规律及与土壤有机质、全氮、微生物量碳氮含量之间的关系。结果表明:不同植被恢复样地0～40cm土层土壤氮素含量差异显著(P0.05),其中20～40cm土层差异显著(P0.05),土壤氮素的矿化效果为人工中间锦鸡儿林地天然中间锦鸡儿林地天然草地平茬人工中间锦鸡儿林地;不同植被恢复模式下0～40cm土层氮素的有效性无显著差异,但在5～10cm、10～20cm、20～40cm土层有极显著差异(P0.01),土壤氮素的有效性表现为:人工中间锦鸡儿林地天然中间锦鸡儿林地平茬人工中间锦鸡儿林地天然草地;表明人工栽植中间锦鸡儿可以有效提升土壤氮素的转化和利用效率。     

商会自治的基石——商会自治规范研究

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。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

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。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

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.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

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。     

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.     

Mechanism of Action of Probiotic Function of Lactobacilli

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.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

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.