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1.
在系统命名的基础上对高等植物光系统II捕光色素蛋白复合体 (LHCII)的结构和功能研究的新进展进行了介绍 ,并对研究中存在的问题进行了讨论。  相似文献   

2.
三江平原沼泽湿地水系统研究浅析   总被引:4,自引:1,他引:3  
综述了沼泽湿地水文研究进展,对其水系统研究的地位和作用进行讨论,并综合分析了其主要内容和研究系统,同时对沼泽湿地水系统研究前景提出了展望。  相似文献   

3.
在系统的命名的基础上对高等植物光系统Ⅱ捕光色素蛋白复合体(LHCⅡ)的结构和功能研究的新进展进行了介绍,并对研究中存在的问题进行了讨论。  相似文献   

4.
淡水生态系统服务及其评价指标体系的探讨   总被引:39,自引:0,他引:39  
对淡水生态系统的重要性及生态系统服务的内涵进行了阐述,指出了当前淡水生态系统服务研究的不足;认为淡水生态系统服务的正常发挥离不开一个健康的生态系统,但少有将两者结合的综合研究,而这样的研究又是必要的。水资源应明确包括水量、水质、水能和水生生物四大要素,以此为基础,对淡水生态系统服务及其评价指标体系进行了论述,并简要介绍其评价方法。文章还对国内相关研究的思路及其技术路线进行了探讨。  相似文献   

5.
五福花科的初步研究   总被引:3,自引:0,他引:3  
本文对五福花科的分类进行了初步研究,提出了新的分类系统,并对其系统演化规律、地理分布等进行了讨论。  相似文献   

6.
经济系统物质流分析研究述评   总被引:2,自引:0,他引:2  
余亚东  陈定江  胡山鹰  朱兵 《生态学报》2015,35(22):7274-7285
作为研究经济系统物质代谢的重要方法,经济系统物质流分析方法近年来在资源与环境管理领域得到了广泛的应用,理论发展非常迅速。对经济系统物质流分析进行了系统综述,以期为更深入的理论研究提供参考。系统回顾了经济系统物质流分析的发展历史,介绍了其核算框架和指标体系。重点对经济系统物质流分析的研究现状进行了总结和述评,研究表明:(1)在经济系统物质流分析指标的核算研究方面:国家层面的核算研究多、方法较为成熟,而区域层面的核算研究尚未形成成熟的核算框架;针对直接流指标的核算研究多,而包含间接流或隐藏流的综合指标的核算方法研究不足;(2)在经济系统物质流分析指标的变化原因研究方面,目前的研究较少,研究方法包括分解分析法和回归分析法:前者多基于IPAT方程的直接分解法,难以考察经济系统内部的结构和技术的变化对经济系统物质流分析指标的影响,而后者则在所识别的经济系统物质流分析指标的影响因素方面具有较大差异。提出了经济系统物质流分析的未来研究方向。  相似文献   

7.
城市公园作为城市中自然景观的重要组成部分,发挥着为人们提供散步漫游、休憩交往场所的重要作用,其内部慢行系统的研究对提升城市公园整体景观品质和游览体验有着重要的意义。以城市公园慢行系统为研究对象,通过实地调研和理论研究相结合的方法,从选线和设计两大方面探讨了城市公园慢行系统的构建。最后以黄山市滨江游园慢行系统为例,对其内部慢行系统的选线规划、景观规划和细节设计进行了具体的规划和设计,对理论研究结果进行验证和反馈,以期为同类型项目提供指导和借鉴。  相似文献   

8.
植物分子系统地理学及其研究进展   总被引:2,自引:1,他引:1  
系统地理学这个概念框架来源于早期对线粒体DNA(mitochondrial DNA,mtDNA)的研究。随着系统地理学研究方法的不断拓展和分子生物学实验技术的渗透,出出了一门新的交叉学科——分子系统地理学(Mokcular phylogeography)。本文简述了分子系统地理学的发展简史和植物分子系统地理学研究常用的分子标记,回顾了近年来植物分子系统地理学方面的研究进展以及存植物研究中的应用。并对植物分子系统地理学研究进行了展望。  相似文献   

9.
1、引言关于三种群生态系统的持续生存的研究已经有了许多结果,应用动力系统的研究方法,文献对一般三种群捕食-被捕食系统和竞争系统的持续生存进行了研究,得到了几个判别法则;文献对一般抽象动力系统的一致持续生存进行了研究,得到了一个充要的判别法则。但是这些法则对系统在边界上的性质要求较高,特别要求系统在边界  相似文献   

10.
双线性系统能对非线性系统很好的近似,可对生态、生物等过程中的许多现象进行描述,对双线性系统研究具有一定的实际价值与理论意义.本文研究了一类离散双线性生态系统的全局渐近稳定问题.针对该系统,给出了一种简单的正规化反馈控制律.运用Lyapunov稳定性理论证明了在此控制律下的闭环系统是全局渐近稳定的.  相似文献   

11.
The effects of angiotensin-II and bradykinin intracerebroventricular microinjections and instillations on the conjunctiva on water and alcohol consumption in rats were compared. The identical effects of peptide instillations on the conjunctiva and intracerebroventricular microinjections were demonstrated. Dipsogenic doses of angiotensin-II for instillations on the conjunctiva in intact rats were greater than or equal to 10 micrograms. At the same time the effective peptide doses in drinking rats were similar to intracerebroventricular drug doses.  相似文献   

12.
A morphometric analysis was done on the lymph capillaries of both left and right ventricles from the rabbit heart. The measurements were made on the lymphatics identified in the subepicardium, myocardium and subendocardium of the ventricular walls. Quantitative evaluations were carried out on light and electron microscopic sections by a computerized image analysis system. The following parameters were selected and measured: (1) the diameter (of area-equivalent circle) of lymph capillaries, (2) the diameter of the uncoated micropinocytotic vesicles (located on the abluminal and adluminal side and in the cytoplasm of the endothelial cell) and the area occupied by the vesicles per unit area of cytoplasm. Differences in the size of the lymph capillaries were found in the three layers (subepicardium, myocardium and subendocardium) of the ventricular walls. The largest vessels were present in the subepicardium both in the left ventricle and in the right one. No significant variations were found in the lymphatics of corresponding regions on both ventricles. Little variations on the mean diameter of the uncoated micropinocytotic vesicles are present in the three regions of the endothelial wall. In the left ventricle only, the subendocardial vesicles are significantly larger than the subepicardial and the myocardial ones (p less than 0.05). The areal density occupied by vesicular system in the three layers of the ventricular wall showed significant differences in both ventricles (p less than 0.05). The vesicles present in the subepicardial vessels occupied the smallest areal density. No significant variations existed in the vesicular areal density between the two ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
M H Morehead  R R Gala 《Life sciences》1987,41(21):2355-2362
Experiments were performed to determine whether the restraint stress-induced decrease in the proestrous prolactin (PRL) surge blocked luteolysis of the corpora lutea (CL), affected ovulation, or prevented the induction of pregnancy/pseudopregnancy in the next cycle. In all experiments rats were either stressed on proestrus and estrus, administered daily sc injections of 1 mg/day of 2-Br-alpha-ergocryptine (CB-154) for 4 days starting on diestrus II or not treated. In one experiment animals were sampled on the afternoon of proestrus to determine the effect of restraint stress on plasma PRL values and sacrificed on the morning of proestrus in the next cycle. Ovaries were removed, weighed, fixed and examined for number of CL. Restraint stress resulted in a significant increase in ovarian weight when compared to controls; CB-154 resulted in significant increases in ovarian weight when compared to stress and control animals. However, only CB-154-treated animals had a significant increase in the number of CL when compared to controls. In another experiment, animals were sacrificed on estrus of the next cycle and the oviducts examined for the number of ova. There were no differences among groups. In the final experiment, animals were placed with males of proven fertility on proestrus of the next cycle and examined for evidence of sperm in the vaginal lavage and/or vaginal plugs. CB-154 prevented the induction of pregnancy or pseudopregnancy due to a carry over effect of the drug on PRL surges. Restraint stress had no significant effect on the induction of pregnancy or pseudopregnancy. We conclude that there is no physiological significance to the stress-induced decrease of the proestrous PRL surge with respect to ovarian function or fertility.  相似文献   

14.
Fractions responsible for the main part of the serological and immunogenic activity differing by the set of antigens were isolated from the salt extracts of parapertussis microbes by gel-filtration on Sephadex G-100, ion exchange chromatography on DEAE-cellulose, and preparative electrophoresis in agar. Fractions, disclosing a sufficiently high serological activity and possessing the immunological properties, but containing the minimal set (2--3 out of 7) antigens, which were included in the initial extract, were isolated in the agar gel in the use of the preparative electrophoresis method.  相似文献   

15.
The yeast Candida tropicalis, Candida utilis, Trichosporon cutaneum were cultivated on the synthetic medium containing additions of group B vitamins (biotin, thiamin) and glucose, glycerol of lactic acid as the sole source. The protein content, amino acid composition, nucleic acids and complex B vitamins were identified in the resultant biomass. The carbon source in the medium affected these indices. The protein and nucleic acid content also depended on the yeast strain.  相似文献   

16.
The effects of hormonally-prolonged gestation on the rabbit placenta were studied in 9 female rabbits. Chlormadinone (a progestagen) was injected im at .23 mg/day beginning with the first day of gestation. 5 of the treated rabbits were killed on the 34th day of gestation and 4 on the 35th day; there were no spontaneous births. In the placentas taken from the treated animals, a transient over-differentiation of the fetal peripheral vascular system and, finally, extensive circulation disorders in the maternal sinus were observed, leading to the formation of infarction placentas. The big fetal vessels were found to be greatly stenosed as a result of intimal proliferations. The maternal decidual arteries had undergone parietal and obturating thromboses. The decidua basalis showed signs of premature detachment of the placenta. The data on prolonged gestation in rabbits are compared with results of similar experiments in rats, and on those available on human over-gestation. As regards the morphological picutre of the placenta, the model of experimentally prolonged gestation in the rabbit appears to be excellently suited for the study of chronic placental insufficiency in human beings.  相似文献   

17.
The effect of undernutrition on ovarian and uterine venous progesterone concentrations and endometrial progesterone content on Days 5 and 10 of the estrous cycle were studied. Forty ewes were synchronized using progestagen pessaries. At pessary withdrawal, the ewes were fed diets to provide either 1.5 or 0.5 times the daily maintenance requirement (Group H, n = 20 and Group L, n = 20, respectively). Ewes fed the low nutrition diet (Group L) had higher mean peripheral progesterone concentrations than those fed the high plane diet (Group H; P < 0.05) but lower endometrial progesterone content on Day 5 (P < 0.05). Neither ovarian nor uterine venous levels were affected by nutrition on either Day 5 or 10. Progesterone concentrations in blood samples collected ipsilateral to ovaries bearing a corpus luteum (CL) were higher than in the contralateral samples (P < 0.001). It is concluded that undernutrition can produce a reduction of endometrial content of progesterone the first week after mating. Since no differences in ovarian venous concentrations were observed, it remains to be shown whether this variation is due to other variables, such as the population of endometrial progesterone receptors or other nonhormonal factors.  相似文献   

18.
The effects of phentolamine on coronary resistance and heart rate, as well as the influence of beta 1-adrenoceptor blockade on phentolamine effects were studied on the isolated cat hearts. Phentolamine reduced coronary resistance in 100% of cases (-25.9 +/- 4.4%; p less than 0.001) and increased heart rate only in 31.6% of cases (+9.1 +/- 1.4%); on average the alterations of heart rate were nonsignificant (p less than 0.1). After beta 1-blockade with Cordanum the rate of coronary dilation reduced (p less than 0.001), the changes in coronary resistance being nonsignificant (p greater than 0.1). Basal coronary resistance and tone during phentolamine infusion without or after beta 1-blockade were identical (p greater than 0.1). Thus, the reduction of coronary resistance during phentolamine infusion was due to beta 1-adrenomimetic activity of the drug.  相似文献   

19.
斑鞘豆叶甲是大豆苗期重要害虫,本文利用扫描电镜技术观察了斑鞘豆叶甲触角感器超微形态与分布。结果表明:斑鞘豆叶甲触角感器绝大部分着生于鞭节,在鞭亚节端部和末节凹陷区感器分布密集,类型较多。基于感器外部形态可分为8种类型:毛形感器Ⅰ型和Ⅱ型、刺形感器、锥形感器、指形感器、腔锥形感器、栓锥形感器Ⅰ型和Ⅱ型、钟形感器和B hm氏鬃毛。其中毛形感器数量最多,其次是锥形感器,钟形感器最少,仅分布于雄虫触角,还着生有大量表皮孔。雌、雄虫触角感器在形态、数量和分布上均存在差异,雄虫毛形和刺形感器显著长于雌虫,刺形感器端部膨大,两种感器的数量也明显多于雌虫;雌虫与雄虫相比末节背面也具感器密集的凹陷区,指形感器短于雄虫但数量显著多于雄虫。斑鞘豆叶甲触角感器种类丰富,分布密集,雌、雄虫感器存在明显的性二型现象,其结构和类型表现出种间分化特性。  相似文献   

20.
This study was designed to investigate the respective damping properties of the annulus fibrosus and nucleus pulposus of the intervertebral disc during propagation of vibration waves through the osteoligamento-muscular axis of the spine. The study was conducted on a 8-10 kg deeply anesthetized baboon. In the first surgical phase five accelerometers were implanted in the first sacral vertebra and on the anterior side of the four lower lumbar vertebrae. The bioinstrumented animal was placed in a restraining chair and exposed to narrow-bandwidth (0-100 Hz) 0.16 G RMS random vibration. Once data was recorded, the nuclei pulposi of the studied discs were removed by suction, the surrounding annuli remaining intact. The still deeply anesthetized animal was again exposed to the same 0-100 Hz, 0.16 G RMS vibration. Results were analyzed and their reproducibility was tested on three animals.  相似文献   

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