71 resultados para Pascal, Jacqueline, 1625-1661.


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Seasonal investigations of size-fractionated biomass and production were carried out from February 1992 to May 1993 in Jiaozhou Bay, China. Microplankton assemblages were separated into three fractions: pico-(0.7-2 mu m), nano- (2-20 mu m) and netplankton (20-200 mu m). The biomass was measured as chlorophyll a (Chl a), particulate organic carbon (POC) and particulate organic nitrogen (PON). The production was determined by C-14 and N-15 tracer techniques. The seasonal patterns in biomass, though variable, were characterized by higher values in spring and lower values in autumn and summer (for Chl a only). The seasonal patterns in production, on the other hand, were more clear with higher values occurring in summer and spring, and lower values occurring in autumn and winter. Averaged over the whole study period, the respective proportions of total biomass accounted for by net-, nano- and picoplankton were 26, 45 and 29% for Chl a, 32, 33 and 35% for POC, and 26, 32 and 42% for PON. The contributions to total primary production by net-, nano- and picoplankton were 31, 35 and 34%, respectively. The respective proportions of total NH4+-N uptake accounted for by net-, nano- and picoplankton were 28, 33 and 39% in the daytime, and 10, 29 and 61% at night. The respective contributions to total NO3--N uptake by net-, nano- and picoplankton were 37, 40 and 23% in the daytime, and 13, 23 and 64% at night. Some comprehensive ratios, including C/N biomass ratio, Chl a/C ratio, C uptake/Chl a ratio, C:N uptake ratio and the f-ratio, were also calculated size separately, and their biological and ecological meanings are discussed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

蕨麻,藏医谓之卓老沙曾,原植物为蔷薇科委陵菜属鹅绒委陵菜Potentilla anserine L.,为多年生草本.在高海拔地区蕨麻根的中下部形成块根,在温暖低平地区不形成膨大的块根[1].蕨麻全草入药,收敛止血,止咳利痰,治各种出血及下痢.块根入药,有健脾益胃、生津止渴、益气补血功效;治脾虚、腹泻、产后贫血、营养不良等症[2].

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文从智能化角度,以信息与控制的分层递阶结构作为信息集成与建模基础,用概率模型描述和控制智能机器人系统或智能控制系统的各种功能,用熵作为处理多种信息(活动)不确定性的测度,探究信息集成和概率建模的通用模式,用实际应用的几个事例简要说明文中方法的有效性。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文给出了机器人关节系统多级自适应控制器的鲁棒性分析.分析表明机器人多级自适应控制系统即使子系统间存在相互关联项和子系统存在未建模特性.采用σ-修正法也能保证系统的输出有界.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

机器人的程序设计问题是智能机器人研究的重要方面。也是自动程序设计的一个重要方面。给定一个机器人的任务描述。应该能够得一个完整的程序代码(用某种程序设计语言书写)。本文描述了一个这样的系统-LRPS。LRPS用一种比较简单的任务描述语言TOL(Task-Oriented Language)来接收用户的任务描述,然后经过分析。规划,最后生成一段用VAL语言编写的程序代码,系统能够给出机器人的宏动作序列--机器人规划。并能对若干知识库进行操作。在规划器中采用了一种新的称为插入法的方法来进行规划,整个系统在IBM-PC机上用PASCAL语言实现。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文是对PUMA-760型机器人的主控制器软件,并进行向VAL-II系统改进。PUMA-760是属于程序控制系统类型的机器人,它包括时间控制装置,信息处理器和执行装置。PUMA-760 的系统控制方式是采用分级控制方式,由一台 PDP-11/23机和八台八位微机组成的二级控制系统,PDP-11/23 作为主控机,六台微机分另对六个轴进行伺服控制,一台微机用于示教盒控制,最后一台微机用于软盘管理。VAL-II 系统在 VAL 系统的基础上,加入了数值运算功能,网络管理和结构化程序设计语句,使得 VAL-II 语言更加清晰,它的向条结构化语句类似于 PASCAL语言中的结构语句(面向用户),网络管理上它采用DEC公司的网络设计标准,数值运算由于引进了浮点运算器,所以它比起 VAL 语言有更强的运算能力。目前汉字卡片的应用,使得终端汉字化成为可能,这里暂且进行了显示信息的改造。关于传感器指令,经分析VAL系统,我所的 PUMA-760 已具备力觉,视觉等指令。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Crosshole Seismic tomography has been broadly studied and applied in the fields of resource exploration and engineering exploration because of its special observing manner and better resolution than normal seismic exploration. This thesis will state the theory and method of Crosshole Seismic tomography. Basing on the previous studies,the thesis studied the initial velocity model,ray-tracing method, and developed the three-dimension tomography software. All the cells that a ray passes through are of the same velocities if the paths from transmitters to receivers are straight. The cells that the each ray passes through are recorded, and rays that pass through each cell are calculated. The ray average velocity which passes through a cell is set as the cell velocity. Analogously we can make a initial node velocity model because the velocity sum is calculated on the all cells which own to a certain node, and the cell number is summed about each nodes,the ratio of the velocity sum to the all cells number is set as the node velocity. The inversion result from the initial node velocity model is better than that of the average velocity model. Ray-bending and Shortest Path for Rays (SPR) have shortcomings and limitations respectively. Using crooked rays obtained from SPR rather than straight lines as the starting point can not only avoid ray bending converging to the local minimum travel time path, but also settle the no smooth ray problem obtained by SPR. The hybrid method costs much computation time, which is roughly equal to the time that SPR expends. The Delphi development tool based on the Object Pascal language standard has an advantage of object-oriented. TDTOM (Three Dimensions Tomography) was developed by using Delphi from the DOS version. Improvement on the part of inversion was made, which bring faster convergence velocity. TDTOM can be used to do velocity tomography from the first arrival travel time of the seismic wave, and it has the good qualities of friendly user interface and convenient operation. TDTOM is used to reconstruct the velocity image for a set of crosshole data from Karamay Oil Field. The geological explanation is then given by comparing the inversion effects of different ray-tracing methods. High velocity zones mean the cover of oil reservoir, and low velocity zones correspond to the reservoir or the steam flooding layer.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

建立以乙睛一水为流动相, 高效液相色谙法侧定大气颗粒物中种优控多环芳烃化合物的方法。用玻璃纤维滤膜采集大气颖杠物, 以二氛甲烷为溶剂, 超声波提取样品, 提取液过滤经溶别转换后在硅胶柱上分离净化,洗脱液经氮气吹干浓缩后用乙晴定容, 用乙睛一水作流动相进行高效液相色谱梯度洗脱分离, 荧光检侧器变波长程序检测。通过实验优化了种多环芳烃化合物的分离和测定条件。种检测限为一户, 日内, , 一和日间一相对标准偏差分别为小于和小于。该法具有快速、灵敏、准确、重现性好的优点, 适合于大气中痕量多环芳烃的浏定。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

为探讨土法炼汞过程中汞蒸汽暴露对炼汞工人健康的影响,测定了贵州省务川土法炼汞区和对照区(贵州省长顺县)人群的尿汞、尿常规参数(pH、葡萄糖、尿胆红素原、潜血、尿蛋白)、尿肌酐和尿B2微球蛋白含量,并对两地区人群进行了详细的健康检查。测定结果显示,土法炼汞区人群尿汞和尿B2微球蛋白的平均含量分别高达779μg·g^-1Cr和208.5μg·g^-1Cr,远远高于对照区人群的尿汞1.24μg·g^-1Cr和尿B2微球蛋白75.4μg·g^-1Cr.分析表明,务川地区土法炼汞人群遭受了较严重的汞蒸汽暴露,部分暴露人群已经表现出轻度慢性汞中毒的症状,其肾脏已经遭受到一定程度的损伤.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

矿产资源开采利用过程中导致的重金属环境污染问题日益严重。我国铅锌矿资源丰富,其开采利用过程中镉的环境污染也日益突出。本文通过对云南兰坪金顶Pb-Zn矿区矿床开采利用过程中镉等重金属元素的环境地球化学行为及矿区生态环境的研究,得出如下主要结论。 1. 矿石淋滤实验表明矿区部分氧化铅锌矿石可以很快被再次氧化或者被溶解并释放出大量镉等有害元素,滤出元素可以迅速发生沉淀或被沉淀物包裹,其释放能力表现为Zn>Pb>Cd。铅锌氧化矿石中菱锌矿组分含量是影响镉淋失的主要因素。在开放体系的水-岩作用下,矿区岩石、矿物的自然风化极易造成当地水系统中镉污染。 2. 矿区不同岩(矿)石中镉含量分布差异比较大,围岩中镉含量为50-650 ppm,平均310 ppm,原生矿中镉含量为14-2800 ppm,平均767 ppm,氧化矿中镉含量为110-8200 ppm,平均1661 ppm,其平均值最高。Zn、Cd地球化学性质的差异导致了二者在原生矿和氧化矿中的不同地球化学分配特点,原生矿Zn/Cd高于氧化矿Zn/Cd,表明氧化环境中镉更容易在氧化矿中富集,而锌更容易被氧化析出到环境中。氧化矿中Cd与Ca呈负相关,这表明Cd的富集和Ca的氧化淋失是同时进行的,并且还可能有Cd对Ca的类质同像代替存在。 3. 矿区上游对照区土壤中的高含量Cd浓度是因土壤母质层重金属高背景值造成的,而非人为污染。矿区中心区土壤受到严重Cd污染,可能与选厂、采场废石堆、尾矿库和露采矿山大范围暴露有关。矿区沿沘江下游两岸土壤中Cd含量远远超出上游土壤背景值和金顶全区土壤背景值,这可能是与污水灌溉有关。通过加权综合污染指数评价法发现矿区土壤污染的主要因子是Cd,其次是Zn和Pb,矿区土壤重金属污染贡献顺序为:Cd>Zn>Pb。矿区土壤污染主要表现为:矿区土壤污染有从中心区向沘江下游扩散区土壤中蔓延的趋势。 4. 矿区水体中出现较高含量的镉,高出天然河流中镉含量的50-100倍。矿区架崖山、北厂和跑马坪等采矿区水体中镉浓度范围在15-30 µg/L之间。矿区水体中镉含量水平表现为:矿山浅层地下水>矿山溪流水>沘江河水。研究结果表明,矿区沘江下游河段水体明显受镉污染,其中水体中镉的平均含量为15.7 µg/L,悬浮物中镉含量为49.3 mg/kg,沉积物中镉含量为203.7 mg/kg。矿区载镉岩石和矿物的自然风化是造成矿区水环境中镉污染的直接原因。 5. 跑马坪采场的废弃石具有较低的Cd含量,而北厂、架崖山采场的废弃石具有较高的Cd浓度,可能与废弃矿石类型本身差异有关。尾矿剖面中的Cd含量,在表层中随剖面深度呈递减趋势,在中层随剖面深度变化不明显,而在底层中明显富集。尾矿库表层尾矿样品中弱酸提取态和可还原态Cd高于底层尾矿样品,相比之下,表层尾矿中Cd等重金属元素易于释放到环境中,对环境的潜在危害大。老尾矿库尾矿砂中Cd金属总量高于新尾矿库尾矿砂,可能还是因为选矿工艺、技术的差异造成的。 6. 矿区污染段水体中硫同位素值较低,远远低于上游非污染区硫同位素值。矿区水体中δ34S值保持了金顶铅锌矿山源区矿山物质硫同位素的特征,显示了矿山来源物质的影响。根据水体硫酸盐中硫同位素稀释原理,研究发现沘江下游水体SO42-中85 %的硫来源于矿山物质。 7. 从矿区筛选出Cd、Zn、Pb的超富集植物共有4种:其中Cd超富集植物有2种,分别是本地生条裂萎陵菜(Potentilla lancinata Card. In Lecomte)和辣子草(Galinsoga parviflora Cav.);Zn超富集植物仅发现有1种植物,为节节草(Equisetum ramosissmum Desf.);Pb超富集植物发现了1种植物,为毛莲菜(Picris hieracioides L.)。这些植物均具备了超富集植物的基本特征,在污染土壤治理与修复方面具有一定的实践意义。 8. 建立了金顶铅锌矿山(床)地质环境模型。Cd的释放、迁移扩散模式为:雨水淋滤时,矿山固体废弃物产生富Cd的酸性或弱酸性矿山排水,通过下渗淋滤发生测向和垂向迁移,进入周边水体和土壤,然后被水系沉积物中针铁矿、方解石等吸附,并在沉降物中沉淀富集,导致矿区主要河流沘江水体的自净能力下降,加速水体的进一步恶化,破坏生物生存环境。矿区受污染水体、土壤和大气中的有害物质通过生物链进入动植物体内,进而危害人类健康。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As a kind of mood, depression is one of the emotions which people experienced usually. Depressive disorder is one of the common mental diseases. There are about 100 million people in the world be disturbed by depression every year. So it is long history that depression is investigated widely in medicine, psychology, and sociology. There are many theorial problems remain to be solved. Viewed from latest vocuments, the development of depression theory is tending to become more complicated. Most of the prior depression theory focused on relation between one factor and depression. Because depressed individuls have various characteristics and factors that cause depression are different, and each factor can explain only part of depression variance, these prior depression theories are defected. As the knowledge about depression accumulated, the view that depression be caused by multifactor is clearer. There is tendency to integrate these cooperational factor into a model while developing a depression theory. In the present study, depression status of 1625 middle school students from junior 1 to senior 3 are measured using Depression Scale of Middle-school Student which is developed by ourselves. From approach of depressive mood, the present study explored depressive diathesis including attributional style, personality, coping style, and self. The relation among depressive diathesis, stress and depression is analysed. The relation between depression and school life adaptation, depression and cohesion, adaptation in family are also analysed from environmental view. At last, relation among environment, stress, depressive diathesis is examined by using covariance structure modelling. Synthesizing the results from the present study, the following conclusions were drawn: (1) There is grade-characteristics in development of depression in middle school students. Depression degree increased with grade. The main reason may be that the stress middle-school students experience increase and self-acceptance decrease with grade; (2) High depressive diathesis is different from low depressive diathesis. the features of high depressive diathesis are that attributing failure to ability or background, low capacity for status, low sociability, low independence, low self-blame, more illusion. The features of low depressive diathesis are that not attributing failure to ability or background, high capacity for status, high sociability, high independence, high self-acceptance, while facing difficulties, using problem-resolving coping strategy, less self-blame, less illusion. Individuals who have high depressive diathesis showed serious depression, and individuals who have low depressive diathesis showed light depression; (3) Depressive diathesis had accumulative effect on depression. More low depressive diathesis, more light is depression. More high depressive diathesis, more serious is depression; (4) Depressive diathesis can predict present depression and future depression. Predicting present depression is more effective than predicting future depression; (5) Individual who has different depressive diathesis experiences different level of stress. Higher the depressive diathesis individual has, higher stress he will experience. Lower the depressive diathesis individual has, lower stress will he experience; (6) There is correlation between life event pressure and depression. Life event pressure can predict a part of variance of depression. Life event pressure has accumulative effect on depression. More life event and higher life event pressure, more serious depression individual will experience; (7) There exits high correlation between depression and school life adaptation which can predict depression; (8) There is high correlative relation between depression and cohesion, adaptation in family which can predict depression; and (9) Environment have more effect on diathesis than on stress. Diathesis has more effect on depression than stress does. The past depression can predict future depression. This study had enlarged the domain of depressive diathesis such as attributional style, personality, coping style, and self, which are analysed wholly. This study had also enriched the connotation of diathesis=stress theory. Above two aspects are theoretical significance of the study. This study provide a framework of mental health educational curriculum in high school and provide the guideline for prevention and cure of depression. It is the practical significance of this study.