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1.
甘南高原农户对极端天气的适应障碍及适应意向   总被引:1,自引:0,他引:1  
王伟军  赵雪雁  万文玉  李花  薛冰 《生态学报》2017,37(23):8089-8100
基于入户调查数据,探讨了甘南高原农户对极端天气的适应障碍,并采用二元Logistic回归模型分析了适应障碍对农户适应意向的影响。结果发现:(1)甘南高原农户面临的规范性障碍最严重,信息技术障碍次之,再次为制度障碍和认知障碍。不同生计农户面临的适应障碍存在差异,其中,纯农户主要面临信息技术障碍,兼业户和非农户则主要面临规范性障碍。(2)纯农户对极端天气的适应意向主要受认知障碍、信息准确性障碍、适应策略选择时机障碍、政策激励障碍和牲畜拥有量的影响,兼业户主要受认知障碍、技术服务障碍、政策激励障碍影响,非农户主要受认知障碍、资源获取性障碍影响。除适应策略选择时机障碍外,其余适应障碍越小,不同生计农户的积极适应意向均越强。最后,提出了解决农户适应障碍的对策建议。  相似文献   

2.
烟草连作障碍与土壤理化性质及微生物多样性特征的关联   总被引:4,自引:0,他引:4  
【背景】烟草是我国最重要的经济作物之一,其忌连作的特点严重影响了我国烟草产业的发展。【目的】通过研究烟草连作障碍、土壤理化性质和微生物多样性特征的关系,为解决烟草连作障碍问题、制定有效的烟草生产技术提供理论基础。【方法】选择连作障碍严重烟田和克服连作障碍烟田作为研究对象,基于高通量测序技术,探究烟田连作障碍情况、烟田理化性质与土壤微生物多样性的联系。【结果】克服连作障碍的烟田土壤pH、总氮和有机质含量显著高于连作障碍严重的烟田土壤,克服连作障碍烟田和连作障碍严重烟田土壤微生物多样性之间不存在显著差异,但土壤微生物优势群落发生了显著改变,烟田土壤的pH、有机质、有效磷、总氮都与微生物群落显著相关。【结论】烟田克服连作障碍的差异,可能与烟田土壤的理化性质以及微生物组成的差异有关,此研究为解决湘西烟区连作障碍问题提供理论基础和技术支持。  相似文献   

3.
学习障碍是学龄儿童较常见的问题之一。近年来,西方学者在学习障碍领域开始引人弹性发展理论,取得了大量的研究成果。本文就弹性发展理论的内容、影响学习障碍儿童弹性发展的保护性因素和危险性因素、弹性发展的作用机制以及学习障碍儿童的弹性干预作了简要的介绍,以期对我国的学习障碍研究和干预有所启发。  相似文献   

4.
认知功能障碍可导致患者日常生活能力、社会适应能力明显下降,严重影响患者的生活质量。根据近年来众多研究显示,认知功能障碍的发生发展与基因、蛋白质、微生物等内环境因素的失调和紊乱有关。基于系统生物学的研究,梳理了近年来国内外研究学者在代谢组学、蛋白质组学、基因组学和肠道微生物组学层面对认知功能障碍的研究,并对系统生物学在认知功能障碍中的应用前景进行了展望,以期为认知功能障碍相关研究提供参考。  相似文献   

5.
摘要 目的:探讨老年帕金森病(PD)患者睡眠障碍的危险因素,并观察睡眠障碍对认知功能、心理状态和衰弱的影响。方法:选取2018年3月~2021年9月期间中国人民解放军海军青岛特勤疗养中心收治的91例老年PD患者作为研究对象,根据是否存在睡眠障碍将入选的91例患者分为睡眠障碍组(n=56)及非睡眠障碍组(n=35)。采用蒙特利尔认知评估量表(MoCA)评估所有患者的认知功能状况。采用汉密尔顿焦虑量表(HAMA)、汉密尔顿抑郁量表(HAMD)评价患者焦虑、抑郁情况。采用Tilburg衰弱评估量表评估所有患者的衰弱情况。采用多因素Logistic回归分析探讨老年PD患者睡眠障碍的危险因素,并观察睡眠障碍对认知功能、心理状态和衰弱的影响。结果:睡眠障碍组的视空间与执行功能、语言、命名、延迟回忆、注意、抽象、定向评分及总分均低于非睡眠障碍组(P<0.05)。睡眠障碍组的HAMA、HAMD评分均高于非睡眠障碍组(P<0.05)。睡眠障碍组的心理衰弱、躯体衰弱、社会衰弱评分及总分均高于非睡眠障碍组(P<0.05)。多因素Losgistic回归分析结果显示:HAMA评分偏高、多巴丝肼片等效剂量偏高、HAMD评分偏高、Hcy偏高是老年PD患者睡眠障碍的危险因素(P<0.05)。结论:HAMA评分偏高、Hcy偏高、多巴丝肼片等效剂量偏高、HAMD评分偏高是老年PD患者睡眠障碍的危险因素。同时,睡眠障碍可加重老年PD患者的认知功能障碍和衰弱程度,增加抑郁焦虑情绪。  相似文献   

6.
王剑飞  韩俊海  张子超 《遗传》2021,(5):501-519
孤独症谱系障碍(autism spectrum disorder,ASD)是一种遗传相关的神经系统发育性疾病,患者主要呈现社交缺陷、沟通障碍、重复刻板行为和学习记忆障碍等核心症状.小鼠模型是探究孤独症谱系障碍的致病机理和寻找潜在治疗方法的重要工具,而小鼠行为学的观测和分析可以帮助人们更好地了解不同遗传操作对相应孤独症表...  相似文献   

7.
摘要 目的:分析脑胶质瘤患者术后睡眠障碍的影响因素,并探讨术后睡眠障碍对机体认知功能、心理状态和康复进程的影响。方法:选择2019年4月~2021年12月期间中国医科大学附属第一医院收治的260例脑胶质瘤患者。根据病例资料收集并记录患者基本信息,采用单因素和多因素Logistic回归分析脑胶质瘤患者术后睡眠障碍的影响因素。以匹茨堡睡眠质量指数量表(PSQI)评估所有患者的睡眠质量;以简易智力状态检查量表(MMSE)、蒙特利尔认知评估量表(MoCA)评估所有患者的认知功能;以焦虑自评量表(SAS)评分和抑郁自评量表(SDS)评估所有患者的心理状态。观察睡眠障碍对机体认知功能、心理状态和康复进程的影响。结果:260例脑胶质瘤患者中,出现睡眠障碍的有98例,睡眠障碍发生率为37.69%。根据是否发生睡眠障碍将患者分为睡眠障碍组(n=98)和无睡眠障碍组(n=162)。单因素分析结果显示:脑胶质瘤患者术后睡眠障碍与性别、肿瘤部位、脑胶质瘤病理分级、肿瘤直径、合并疾病数量、术后疼痛评分有关(P<0.05),而与年龄、体质量指数、文化程度、家庭人均月收入、手术时间、术中出血量、肿瘤占位症状、吸烟史、饮酒史、术前卡式功能状态(KPS)评分无关(P>0.05)。多因素Logistic回归分析结果显示:性别为女、合并疾病数量2种及其以上、术后疼痛评分偏高、肿瘤部位为多个脑叶、脑胶质瘤病理分级为Ⅲ级是脑胶质瘤患者术后睡眠障碍的危险因素(P<0.05)。睡眠障碍组的MoCA、MMSE评分均低于无睡眠障碍组(P<0.05)。睡眠障碍组的SAS、SDS评分均高于无睡眠障碍组(P<0.05)。睡眠障碍组的术后恢复进食时间、首次下床活动时间、尿管拔除时间、术后住院时间均长于无睡眠障碍组(P<0.05)。结论:脑胶质瘤患者术后睡眠障碍的发生率较高,性别、术后疼痛评分、合并疾病数量、脑胶质瘤病理分级、肿瘤部位均是睡眠障碍的影响因素,睡眠障碍会影响患者的认知功能,增加抑郁焦虑程度,影响康复进程。  相似文献   

8.
三七连作障碍研究进展   总被引:15,自引:0,他引:15  
三七是中国名贵中药材之一,但其在种植环节中存在严重的连作障碍现象。连作障碍产生的原因主要有根际土壤微生物群落变化、土传病虫害增加、化感物质积累及其自毒作用、土壤理化性状恶变等。以前三七连作障碍研究多集中于单一因素对连作障碍的影响及三七病虫害防治,疏于综合分析各种因素间的内在联系和相互影响。本文总结了作物连作障碍形成机制的最新研究进展,综合分析了各因素间可能存在的关系,首次提出了各因素对三七连作障碍影响指数的评估方法,建议了未来研究方向,旨在为揭示三七连作障碍形成机制提供参考,并为连作障碍消减提供理论依据。  相似文献   

9.
大蒜是我国重要的经济作物,大蒜连作障碍是制约其产量和品质的关键因素.本文从连作障碍对大蒜生长的影响入手,通过阐述大蒜土壤微生物群落失衡、土壤养分不均衡、自毒作用及各因素相互关系等,解析大蒜连作障碍形成的机理机制.同时,对目前大蒜生产中常用的,防治连作障碍的手段进行分析,最后对大蒜连作障碍研究方向做出展望.  相似文献   

10.
在制浆造纸过程中,沉积的树脂会影响纸浆和成纸质量,降低设备的运行效率,最终造成经济损失。由于传统控制树脂障碍的方法不能很好地解决这一问题,因此具有高效催化和无污染的特性的生物酶法在该方面得到快速发展。文中介绍了树脂的成分、存在形式和控制树脂障碍的生物酶,重点介绍了脂肪酶、甾醇酯酶、漆酶和脂氧合酶控制纸浆中树脂障碍的机理和工艺研究方面的进展,指出了生物酶控制树脂障碍技术目前存在的主要问题,提出了该领域的主要研究方向,并对生物酶控制树脂障碍技术进行了展望。  相似文献   

11.
Dietary intakes of tomatoes and tomato products containing lycopene have been shown to be associated with decreased risk of chronic diseases such as cancer and cardiovascular diseases in numerous studies. Serum and tissue lycopene levels have also been inversely related to the risk of lung and prostate cancers. Lycopene functions as a very potent antioxidant, and this is clearly a major important mechanism of lycopene action. In this regard, lycopene can trap singlet oxygen and reduce mutagenesis in the Ames test. However, evidence is accumulating for other mechanisms as well. Lycopene at physiological concentrations can inhibit human cancer cell growth by interfering with growth factor receptor signaling and cell cycle progression specifically in prostate cancer cells without evidence of toxic effects or apoptosis of cells. Studies using human and animal cells have identified a gene, connexin 43, whose expression is upregulated by lycopene and which allows direct intercellular gap junctional communication (GJC). GJC is deficient in many human tumors and its restoration or upregulation is associated with decreased proliferation. The combination of low concentrations of lycopene with 1,25-dihydroxyvitamin D3 exhibits a synergistic effect on cell proliferation and differentiation and an additive effect on cell cycle progression in the HL-60 promyelocytic leukemia cell line, suggesting some interaction at a nuclear or subcellular level. The combination of lycopene and lutein synergistically interact as antioxidants, and this may relate to specific positioning of different carotenoids in membranes. This review will focus on the growing body of evidence that carotenoids have unexpected biologic effects in experimental systems, some of which may contribute to their cancer preventive properties in models of carcinogenesis. Consideration of solubility in vitro, comparison with doses achieved in humans by dietary means, interactions with other phytochemicals, and other potential mechanisms such as stimulation of xenobiotic metabolism, inhibition of cholesterogenesis, modulation of cyclooxygenase pathways, and inhibition of inflammation will be considered. This review will point out areas for future research where more evidence is needed on the effects of lycopene on the etiology of chronic disease.  相似文献   

12.
Ichthyoplankton surveys are made in lagoon water bodies of the south-eastern part of Sakhalin (the Vavai-Chibisan system of lakes, Lake Tunaicha, Lake Izmenchivoe) from April until November 2002–2007. Comparative characteristics of ichthyoplankton complexes in the ice-free period is given. In the investigated lagoon lakes, differences in the species composition of the ichthyoplankton by the number and time of appearance of the maxima of abundance of eggs and larvae are noted, and also related to morphological structure and hydrological conditions of water bodies. In lagoon lake Izmenchivoe with a salinity not less than 26‰, the eggs and larvae of marine fishes only takes place while, in Vavai-Chibisan lakes, that of freshwater fishes only takes place. In brackish lake Tunaicha, the lowest number of fish species reproduce. In the Vavai-Chibisan system and in Lake Izmenchivoe, one maximum of abundance of ichthyoplankton in June is recorded and, in Lake Tunaicha, two maxima (the highest in June and less expressed in August) are recorded. Irrespective of the species composition, the ichthyoplankton complexes of lagoon lakes have general traits determined by hydrological conditions of water bodies and by their general origin and geographic situation: prevalence of eggs and larvae of low boreal fish species, the maximum species diversity in the late spring-early summer, and decrease of abundance in cooler years.  相似文献   

13.
Summary MAO of the brain was investigated histochemically in mice, rats, guinea pigs and rabbits. Fresh frozen sections were subjected to the tryptamine-tetrazolium method by Glenner, Burtner and Brown (1957).MAO activity of the brain of 4 animal species is generally similar with respect to its pattern of distribution. However, the intensity of enzyme action of the brain as a whole differs somewhat in animal species, being highest in guinea pigs, intermediate in rats and lowest in mice and rabbits. The enzyme action occurs mainly in the neuropil of the cerebral grey matter, while weak or negative activity is generally observed in the white matter excepting the tractus retroflexus of Meynert.The marked activity is encountered in the interpeduncular nucleus, locus coeruleus, area postrema, dorsal nucleus of the vagus nerve, hypothalamus, habenular nuclei and midline nuclear group of the thalamus, nucleus of the brachium conjunctivum, and central grey matter. The enzyme activity is weak or negative in the neocortex, striatum, mamillary body, thalamic nuclei (excepting the habenula and midline nuclear group), subthalamic nucleus, substantia nigra, red nucleus and nuclei of the somatic cranial nerves.The possible function and significance of MAO in the brain were discussed particularly by comparing the sites of this enzyme with those of succinic dehydrogenase and cytochrome oxidase, and the inverse relation between these enzymes was suggested.  相似文献   

14.
The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.  相似文献   

15.
青蒿素生物合成机理研究现状   总被引:10,自引:1,他引:9  
赵兵  王玉春  欧阳藩   《广西植物》1999,19(2):154-158
本文总结了目前有关青蒿素生物合成机理方面的研究,主要包括青蒿素生物合成中生理因子的影响,青蒿素生物合成中间体及前体,青蒿素生物合成细胞定位等。指出了存在的一些问题及今后的研究发展前景。  相似文献   

16.
目的探讨肠道菌群和粪便炎性标志物在炎症性肠病(IBD)活动度评估中的临床价值。方法共纳入120例IBD患者为研究组,其中溃疡性结肠炎(UC)患者68例,克罗恩病(CD)患者52例。选择30例经结肠镜检查正常的健康体检者为对照组。采集全部研究对象的新鲜粪便标本进行粪便细菌培养及炎性标志物检测,比较不同疾病活动度IBD患者的肠道菌群及粪便钙卫蛋白(FC)、乳铁蛋白(LF)、基质金属蛋白酶-9(MMP-9)、髓过氧化酶(MPO)水平的变化。结果与对照组比,UC和CD患者肠道中肠杆菌、肠球菌、拟杆菌、消化球菌及酵母菌数量均明显增加(P0.05),双歧杆菌、乳杆菌及真杆菌数量明显减少(P0.05)。UC患者梭菌数量较对照组增加(P0.05),CD患者梭菌数量较对照组减少(P0.05)。UC、CD活动期患者肠杆菌、肠球菌、拟杆菌、消化球菌及酵母菌数量明显多于缓解期患者(P0.05),双歧杆菌、乳杆菌及真杆菌数量明显少于缓解期患者(P0.05),且重度活动期患者肠道菌群改变较轻、中度活动期改变更明显(P0.05)。UC活动期患者梭菌数量明显多于缓解期(P0.05),CD活动期患者梭菌数量明显少于缓解期(P0.05)。UC和CD患者粪便中FC、LF、MMP-9及MPO水平均显著高于对照组(P0.05)。UC、CD活动期患者FC、LF、MMP-9及MPO水平显著高于缓解期患者(P0.05),且重度活动期患者高于轻、中度活动期患者(P0.05)。结论肠道菌群变化和粪便中FC、LF、MMP-9及MPO水平可作为IBD患者疾病活动性评估的辅助指标。  相似文献   

17.
Histologic sections of arteries can be used to generate three-dimensional (3D) geometric models and identify structural constituents. However, geometric distortions are introduced by fixation, embedding and sectioning; distortions which can, for example, lead to errors in stresses predicted by finite element models. We developed a method to measure and correct for distortions caused by acrylic processing and applied it to intact, healthy porcine coronary arteries. Micro-computed tomography was used to image arteries in the fresh and embedded states. Tissue blocks were sectioned, stained and imaged using a light microscope. Each section contained four registration marks used to determine strains introduced by sectioning and staining. Using these three image sets, 3D geometric models were generated and distortions were measured. Fixation, processing, and embedding resulted in shrinkage of 6.4+/-2.3% axially and 35.4+/-5.0% in mean cross-sectional area (n=5). Shrinkage in a cross section was well characterized by a uniform, equibiaxial strain. Sectioning and staining resulted in additional compressive strains in the sectioning direction of 0.067+/-0.011 and, in the direction perpendicular to sectioning, of 0.023+/-0.005 (n=5). These strains are assumed uniform and form the basis for correcting section geometry. Reconstructions using corrections for sectioning and shrinkage-related distortions had errors of 1.6+/-0.5% (n=5) and 4.0+/-1.7% (n=5), respectively.  相似文献   

18.
Flocks of birds are highly variable in shape in all contexts (while travelling, avoiding predation, wheeling above the roost). Particularly amazing in this respect are the aerial displays of huge flocks of starlings (Sturnus vulgaris) above the sleeping site at dawn. The causes of this variability are hardly known, however. Here we hypothesise that variability of shape increases when there are larger local differences in movement behaviour in the flock. We investigate this hypothesis with the help of a model of the self-organisation of travelling groups, called StarDisplay, since such a model has also increased our understanding of what causes the oblong shape of schools of fish. The flocking patterns in the model prove to resemble those of real birds, in particular of starlings and rock doves. As to shape, we measure the relative proportions of the flock in several ways, which either depend on the direction of movement or do not. We confirm that flock shape is usually more variable when local differences in movement in the flock are larger. This happens when a) flock size is larger, b) interacting partners are fewer, c) the flock turnings are stronger, and d) individuals roll into the turn. In contrast to our expectations, when variability of speed in the flock is higher, flock shape and the positions of members in the flock are more static. We explain this and indicate the adaptive value of low variability of speed and spatial restriction of interaction and develop testable hypotheses.  相似文献   

19.
A simple case is considered in which the rate of a two-step reaction depends on pH because the intermediate formed in the first step has to gain (or lose) a proton before it can react in the second step, and in which the rate-determining step therefore changes with pH. The curves of reaction rate against pH are shown to be symmetrical, and the sharpest peak possible has a width at half its height of 1.53pH units, i.e. of 2log(3+2 radical2). Any particular curve for this situation proves to be identical with a curve that could be generated for the pH-dependence of a single-step reaction in which the rate is proportional to the concentration of a particular ionic form of a reactant. Curves for the latter situation, however, can have forms impossible for the former case in which the rate-determining step changes, but only if the protonations that activate and deactivate the reactant are co-operative. The peak can then become even sharper, and its width at half its height can fall to 1.14pH units, i.e. to 2log(2+ radical3).  相似文献   

20.
In in vivo and in vitro experiments there have been shown different mechanisms of regulation of hypothalamic vasopressinergic neurons, including regulation due to changes of activity level of brain catecholaminergic and NPY-ergic neurons innervating hypothalamic vasopressinergic cells. We demonstrated in in vitro experiments that dopamine and noradrenaline had no effects on vasopressin expression, but inhibited its release from cell perikarya in supraoptic and paraventricular nuclei of hypothalamus. Besides, activity of vasopressinergic neurons might probably be regulated via activation of synthesis of these neurotransmitters in vasopressinergic cells themselves in the supraoptic and paraventricular nuclei. To activate synthesis of various neurotransmitters, in our case, catecholamines and NPY, in vasopressinergic neurons, different stimuli adequate to trigger or activate synthesis of these substances are required. Synthesis of catecholamines in vasopressinergic cells of supraoptic and paraventricular nuclei was revealed after immobilization stress and adrenalectomy. NPY is synthesized in neurons of hypothalamic neurosecretory centers in norm, and its synthesis increases at disturbances of NPY-ergic innervation of vasopressinergic cells.  相似文献   

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