海南省热带农业废弃物资源化利用状况及对策

海南终年可以进行农业生产,以至终年均有大量农业废弃物产生。文章阐述海南省热带农业废弃物资源化利用状况及存在的问题,提出海南省热带农业废弃物资源化利用的对策,其目的在于促进海南省热带农业废弃物资源化利用水平的提高。     

Internally generated cell assembly sequences in the rat hippocampus

A long-standing conjecture in neuroscience is that aspects of cognition depend on the brain's ability to self-generate sequential neuronal activity. We found that reliably and continually changing cell assemblies in the rat hippocampus appeared not only during spatial navigation but also in the absence of changing environmental or body-derived inputs. During the delay period of a memory task, each moment in time was characterized by the activity of a particular assembly of neurons. Identical initial conditions triggered a similar assembly sequence, whereas different conditions gave rise to different sequences, thereby predicting behavioral choices, including errors. Such sequences were not formed in control (nonmemory) tasks. We hypothesize that neuronal representations, evolved for encoding distance in spatial navigation, also support episodic recall and the planning of action sequences.     

宁夏人工甘草田节肢动物群落结构及多样性研究

采用系统分析方法研究了甘草田节肢动物的物种构成、群落丰富度、均匀度、多样性、集中度及其时间动态和主要种群的垂直结构,结果表明,银川地区甘草田优势种为甘草萤叶甲（Diorhabda tarsalis Weise）、黄草地螟（Loxostege verticalis Linnaeus）、黄直条跳甲（Phyllotreta vittula Redtenbacher）、蚜虫类（Aphids）、盲蝽类（Mirids）等．甘草田节肢动物群落及各营养层结构特征呈规律性的变化,其中,基位物种营养层的个体数量随时问变化趋势与节肢动物总群落一致．     

杨梅凋萎病菌侵染、传播及树体内分布规律

为了制定有效的杨梅凋萎病防控措施,对凋萎病菌分生孢子侵染、传播、病害周年发生动态及病菌在树体内分布规律进行了研究。结果表明：2×101～2×106 mL-1浓度范围内的分生孢子溶液都能侵染杨梅致病,主要通过嫩枝的皮口及伤口侵入,有2个侵染高峰期分别是5月和6月中旬至7月中旬。凋萎病菌分生孢子周年均可捕捉到,5月中旬至6月中旬和8月底至10月中旬为两个分生孢子捕捉高峰期。凋萎病周年都有新病枝出现,发病高峰期集中在9月中旬至11月初,在果园内海拔低、流水冲刷严重的位置先发病。周年内发病杨梅树内拟盘多毛孢的分离菌株数及DNA拷贝数都是健康树的2～6倍。凋萎病菌可以周年寄生在杨梅的整个树体内,没有明显的菌量高峰期,嫩枝位置菌量最大。     

退化红壤区笋用小径竹幼林结构的变化规律

以红壤丘陵地植被恢复、生态环境改善和生产潜力发挥为目标,以优质笋用小径竹红壳竹Phyllostachys iridescens、早园竹Phyllostachys propinqua为对象,历时5 a定位研究竹子幼林结构主要因子的年际变化规律.结果表明:红壳竹和早园竹抽鞭发笋能力强,成竹率高,年际立竹量变化明显,以造林后第2年增加最为显著,可分别达到2 430株*hm-2和2 970株*hm-2,第3年成林投产.新竹平均胸径造林后第3年分别为3.54 cm和3.21 cm.第5年立竹量和立竹径级达到丰产林分结构水平.红壳竹和早园竹地下鞭系多分布于土壤上层20 cm区间,造林后第3年鞭系长度达10 m*m-2以上,平均鞭径分别为1.75 cm和1.32 cm,鞭系径级均匀度提高.单位面积林地鞭系侧芽数随着造林年限的增加显著增多,造林后第3年分别是第1年的119.4%和202.9%.指出2竹种在红壤丘陵地适应性好,可规模化推广应用.造林母竹标准为2.5～3.5 cm径级的1～2年生健康立竹,初植密度900～1 500株*hm-2.加强幼林期土壤管理和竹林结构调控是早成林和良好经济性状表现的主要措施.表6参12     

Growth-rings of trees: their correlation with climate

Many differences in the ring-width growth within a tree may be attributed to changing supplies of food and hormones. In moist sites or during periods of favorable climate, there may be sufficient food for the production of wide rings throughout the tree. But in dry sites or during years of low moisture and high temperatures, food competition within the tree is likely to be greater and the cambium at the base of the stem is likely to receive a limited food supply and may produce narrow rings. The cambium at the stem base depends upon the entire crown for food, hence ring growth reflects the tree's ambient climate. But, the cambium in the top of the tree or in the upper branches depends upon a more restricted portion of the crown for its food and hormone supplies. The rings produced by the cambium vary greatly from branch to branch and are less reliable indicators of the climate surrounding the entire tree than rings at the tree base. Therefore, ring series at the base of trees in semiarid sites provide the most reliable, as well as the longest, record of macroclimatic variation. Tree-ring widths in certain coniferous species growing in semiarid sites appear to represent the integrated effect of climate on food-making and food accumulation in the crown throughout the 14 to 15 months previous to and including the period of growth. Trees in warm, low-elevation sites may utilize winter moisture most efficiently; trees in cool, high-elevation or more northern sites may utilize early summer and early autumn moisture most efficiently. But even with these differences, a significant amount of variance is found to be common among tree-ring series from a wide range of sites, species, and geographical areas in western North America (14, 19, 34), emphasizing a common dependence of ring widths on the gross regional patterns of precipitation and temperature. The remaining variance, which is not correlated among sites, may be attributed to local en-vironmental and climatic differences, to variability among and within trees, and to compounding effects of occasional fires, insect or other infestations, and recurring years of high seed production. It is evident that a large portion of the variability in ring-width patterns from semiarid sites in western North America does reflect differences in climate from year to year. If ring chro- nologies are derived from a number of trees in semiarid sites and if adequate corrections for age and trend are made, these chronologies may be used to reconstruct a first approximation of annual, or somewhat longer period, climatic fluctuations in the past (19).     

Synaptic assembly of the brain in the absence of neurotransmitter secretion

Brain function requires precisely orchestrated connectivity between neurons. Establishment of these connections is believed to require signals secreted from outgrowing axons, followed by synapse formation between selected neurons. Deletion of a single protein, Munc18-1, in mice leads to a complete loss of neurotransmitter secretion from synaptic vesicles throughout development. However, this does not prevent normal brain assembly, including formation of layered structures, fiber pathways, and morphologically defined synapses. After assembly is completed, neurons undergo apoptosis, leading to widespread neurodegeneration. Thus, synaptic connectivity does not depend on neurotransmitter secretion, but its maintenance does. Neurotransmitter secretion probably functions to validate already established synaptic connections.     

管道数据遥测系统

管道常常经过人烟稀少地区，为保证管道安全运行，必须时刻监测管道运行情况，及时采集温度，压力，地电位等数据，并将其传送到调度室，以备分析，管道数据遥测系统用 完成这些工作。该系统采用４８６工业控制机作为上位机，其程序用ＰＡＳＣＡＬ语文编制，在ＵＣＤＯＳ５．０操作系统中运行；     

城市化进程中的农村居民点用地变化分析 ——以广州市为例

随着社会经济的发展,在区域建设用地变化中,占重要地位的农村居民点用地变化,已经成为城乡一体化进程中值得关注的问题。以城市化为角度对广州市农村居民点用地现状和变化进行了分析,研究发现在1997~2002年间,广州市的城市化水平综合指标由68.28增加到75.28,年平均增长的比率为1.92%,而农村居民点用地的变化非常平稳,在6年间共增长了796.67hm2,年平均增长0.47%。以上数据反映广州市农村居民点用地变化滞后于经济发展和城市化。广州的城市化是以自组织为主的城镇化,产业与居住的分散化决定了小城镇发展呈现均衡性特征。这样实质上把有限的农村空间割裂为多个不大的发展中心。这种多中心往往导致无中心,即建设无重点、发展无中心、各乡镇过度竞争,造成区域内资源的不合理流动与低效率配置,影响资源向优势区位的流转,无法形成土地资源的集约利用,最终导致农村居民点用地变化滞后于经济发展和城市化。针对农村居民点用地状况,当前对策主要是依托城市化对农村居民点进行土地整理规划使其用地变化向规模减少、集约利用发展。广州市有农村居民点的各区(县级)市,发展情况各不相同,根据不同的社会经济发展条件和地理条件可以对上述区域进行分类,分别采用适合的模式。     

Coal mine explosions: seasonal trends

An analysis of disaster reports on coal mine explosions indicates that gas explosions are randomly distributed throughout the year, whereas dust explosions (which may or may not be triggered by a gas explosion) occur with greater frequency during the dry fall and winter months. The lack of adequate moisture during cold weather tends to increase the rate and severity of the dust explosions.     

A global and long-range picture of energy developments

Most studies of energy supply and demand ignore either global inter-dependence or the long time spans necessary to adjust to new energy sources. The International Institute for Applied Systems Analysis has therefore studied on a global scale, for seven major world regions, the balance between energy supply and demand for the next 50 years. Reported here are the results for two benchmark scenarios. In the "low" scenario world energy consumption increases from today's 8.2 terawatt-year per year to 22 terawatt-year per year in 2030; in the "high" scenario, consumption increases to 35 terawatt-year per year. The study showed that time will be the limiting constraint in adapting the energy supply infrastructure to changing resource availability; resources will be available until the second half of the next century, but a strong shift will be required to low-grade fossil fuels such as shale oil and tar sands. Each scenario studied indicated increased environmental problems associated with increased use of fossil fuels, and potential geopolitical problems associated with the world distribution of resources.     

瓯江干流丽水段渔业资源的初步研究

2009年3月、2009年6月—2010年2月,作者在瓯江干流丽水段设3个采样点,每月一次对瓯江干流丽水段的渔业资源进行了调查和分析。共采集鱼类标本2 579尾,分别隶属于5目,13科,41属,53种。其中,鲤形目鱼类种数最多,鲤科鱼类37种,占样本总数的69.81%,其次是鲇形目和鲈形目;鳗鲡目和合鳃鱼目种数较少,仅1种。全年优势种为圆吻鲴(Distoechodon tumirostris)、大眼华鳊(Sinibrama macrops)和黄颡鱼(Pel-teobagrus fulvidraco),分别占样本总数的33.00%、12.52%和11.36%;Margalef丰富度指数(D)2009年7月～翌年1月呈递减趋势,其中2009年7月最高。Shannon-Wiener多样性指数(H’)月变化幅度不大,只是2009年7月和8月稍高。Pielou均匀度指数(J’)全年较恒定。瓯江干流丽水段主要经济鱼类有唇鱼骨、鮠科鱼类(黄颡鱼等)、斑鳜和鳜等。2009年6月平均密度最高为15.53尾/网,全年在st.2采到的鱼类种数最多(40种),在st.3采到的鱼类种数最少(27种)。     

近56年玉门四季降水量对气候变化的响应

利用1953～2008年玉门镇四季降水量,分析了近56年玉门的四季降水量变化趋势,气候突变、异常年份等。结果表明,春季降水量长期变化趋势不明显;夏季降水量呈上抛物线变化趋势,秋季表现为增多趋势,冬季降水量呈明显的下抛物线变化趋势。20世纪50年代除冬季降水量较多外,其他各季降水量都较少;60年代春季降水量较多;70年代夏季降水量较多;60年代和80年代秋季降水量都较少;90年代后冬季降水量较多。冬季降水量增多与气候变暖的响应更强;夏季降水量在1979年发生了突变,之前呈增多变化趋势．之后呈减少变化趋势,冬季降水量在1984年发生了突变,之前呈减少变化趋势,之后呈增多变化趋势。     

北京地区杏树冰核活性细菌种类及其消长动态规律的研究

 【目的】弄清冰核活性细菌（INA细菌）在杏树上分布种类及分布与年消长动态规律，对于通过防治INA细菌防御杏树晚霜冻害具有重要的意义。【方法】对北京杏主产区27个杏栽培品种及山杏进行调查，采用形态及生理生化方法进行种类鉴定，采用小液滴冻结法测定冰核活性。【结果】共分离到22株-5℃有活性INA细菌菌株，被确定为2个属中的3个种： 假单胞菌丁香致病变种（Pseudomonas syringae pv.syringae）10株，占45.5%；成团泛生菌（Pantoea agglomerans）9株，占40.9%；凤梨泛生菌噬夏孢子致病变种（Pantoea ananas pv.uredovora）3株，占13.6%。成团泛生菌为杏树上首次发现的INA细菌，‘玉巴达’杏树上的INA细菌（P. agglomerans）数量分布存在3个高峰期：花期（3月末至4月初）、果实发育期（5至6月初）、越冬初期（12月），夏秋季及寒冬难以分离到INA细菌。【结论】INA细菌分布数量与杏树所处地理位置及生态条件有关，杏不同器官上分离到的INA细菌的频率也存在差异。     

高校新生入学教育问题与对策浅析

新生入学教育是高校的一项常规性工作。阐述了入学教育的内涵,并从入学教育的时间、内容和形式3个方面分析了入学教育中存在的问题,提出了相应的对策：入学教育的时间应贯穿整个大学一年级,教育的内容要根据新生的特点与时俱进及时更新要与教育时间合理匹配,教育方式要注重灵活性和有效性,要结合一些感性的活动与学生双向交流。     

朝阳县气象灾害发生规律与防御措施探讨

根据朝阳地区1954～2008年的气象资料,分析了当地气象灾害发生规律。其中干旱在全年内均可发生,以春季频率最高;冰雹主要发生在5～9月,6～8月占全年的70%;雷电5～9月占全年的96%,6～7月占全年的52%;霜冻在春秋两季发生,春季受灾有37.5%的年份,秋季受灾有15%的年份。指出干旱、冰雹、雷电和霜冻是朝阳县主要威胁农业经济发展的气象灾害,并提出了相应的科学的防御措施。     

基层农资经销商储货积极性下降——09年下半年化肥销售趋势探析

<正>对于化肥行业来说,2009年的春耕肥料销售给了我们很多意外,不管是生产企业还是经销商,都感觉今年的化肥市场越来越难以捉摸,因此,对于2009年下半年该如何操作都感觉很困惑,生产企业想提前为自己的产品找出路,但经销商宁肯库存极低也不愿意提前进货。为了     

基于参数化零件图的二维装配图修改技术

在综合考虑参数化零件图的复制和对装配图中零件图的计算机识别的基础上，构造了装配图的参数化修改模型，结合基于深度测试的装配消隐算法阐述了一种基于参数化零件图的二维装配图修改技术。实际应用结果表明，由此技术生成的装配图可进行参数化尺寸驱动修改，并且在装配图的构建过程中也可动态尺寸驱动修改零件图，从而使装配图的生成和修改变得方便和直观。     

Molybdenum as a Factor Limiting Primary Productivity in Castle Lake,California

A trace-element deficiency is evident from carbon-14 bioassays of Castle Lake's natural phytoplankton populations. Increase in photosynthetic rates with the addition of molybdic acid or sodium molybdate has been demonstrated throughout the year. It is likely that other trace elements may also be found to be limiting factors in lakes having a limited watershed.     

近45年金华市晚稻安全齐穗期的变化分析

 确定晚稻安全齐穗期是安排各品种播栽期的重要依据。由北至南选取金华市3个代表地点(东阳、婺城、武义)近45年9-11月逐日日平均温度资料,利用mk突变检验法和t滑动检验法寻找两类晚稻安全齐穗温度的变异年份,籼稻为1999年,粳稻为1991年;并根据生产上常用的籼稻和粳稻安全齐穗期指标,得出近45年籼稻1999年之前、粳稻1991年之前及之后3地晚稻保证率分别为50%,80%,90%的安全齐穗期,发现籼稻在1999年之后各地的平均安全齐穗期较1999年之前普遍延迟5～6 d,粳稻在1991年之后各地的平均安全齐穗期较1991年之前普遍延迟6～10 d,且两类晚稻安全齐穗期的变异明显增大。本研究分析提出由北至南金华3个地点籼稻安全齐穗期分别为9月14日、9月16日和9月14日,比生产中习惯应用的安全齐穗期延迟约4 d;粳稻安全齐穗期分别为9月24日、9月24日和9月23日,比生产中习惯应用的安全齐穗期延迟2～3 d。