链霉素对海洋微藻的毒物刺激效应

实验选用链霉素对六种海洋微藻进行实验 ,发现六种海洋微藻普遍对链霉素具有抗性。其中只有角毛藻和三角褐指藻在实验范围内 (0～ 50 0 mg/ L)测到了 72 h的半抑制浓度 ,EC50 分别为346 mg/ L和 4 4 5mg/ L。其它四种均未测到。而且当链霉素浓度为 30 mg/ L时 ,对六种海洋微藻普遍具有生长刺激效应 ,即毒物刺激效应。     

In-situ rainwater harvesting and gravel mulch combination for corn production in the dry semi-arid region of China

A field study was conducted to determine the effect of a combination of ridge and furrow method of in-situ rainwater harvesting with gravel mulch on corn production, soil moisture storage, and water-use efficiency in the dry semi-arid region of China. Results showed that plastic-covered ridges had an average runoff efficiency (runoff/rainfall) of 87% as compared to 7% for bare ridges, and could generate runoff at a threshold value of 0·8±0·2 mm rainfall. Bare ridges produced runoff only under high intensity rainfall events, and was ineffective for harvesting rainfall in the study area. The plastic-covered ridge and gravel-mulched furrow method of rainwater harvesting was effective in conserving moisture and increasing yield and water-use efficiency. The grain yield in this treatment was 1·9 times that of the conventional flat soil cultivation (control), and the water-use efficiency was 1·8 times that of the control. The good performance of the film-covered surface ridges and gravel-mulched furrows is attributed to the better utilization of light rains, improvement of infiltration in the root zone, and suppression of evaporation losses.     

Softs of Fildes Peninsula, King George Island, the maritime Antarctic: Part I. Formation processes and pedogenetic particularities

Based on the data obtained from tens of the investigated soil profiles scattered over the Fildes Peninsula, King George Island, the maritime Antarctic, the soil-forming processes were discussed. It was concluded that on the weathering crusts resulted from various physical courses, the strong freeze-thaw action within regolith, significant organic matter accumulation, evident leaching and illuviation, as well as initial argillification dominated the formation and development of the soils on the Fildes Peninsula. Furthermore, this study indicated that the juvenility of genesis, poor profile-expression, variation in column thickness, etc. characterized the pedogenetic features of the soils of the Fildes Peninsula.     

PI-RADS v2.1联合PSA相关指标预测PSA灰区前列腺癌的价值研究

目的:探讨建立前列腺影像报告及数据系统(PI-RADS v2.1)联合前列腺抗原(PSA)相关衍生物的Logistic模型对PSA灰区(4～10 ng/mL)前列腺癌(PCa)的诊断价值.材料与方法:回顾性分析经病理证实的49例前列腺癌(PCa)和118例非癌患者的资料,包括年龄、tPSA、fPSA、PI-RADS v...     

Probability-based analytical model for predicting the post-earthquake residual deformation of SDOF systems

A probability-based analytical model for predicting the seismic residual deformation of bilinear single-degreeof-freedom(SDOF) systems with a kinematic/Takeda hysteretic model is proposed based on a statistical analysis of the nonlinear time history response,and the proposed model explicitly incorporates the influence of record-to-record variability.In addition,the influence of primary parameters such as the natural vibration period,relative yield force coefficient,stiffness ratio and peak groun...     

中国典型钴矿床地质特征及重点地区矿产资源预测

我国既是钴矿资源消费大国,又是钴矿资源进口大国,受新能源电动汽车工业的影响,近年来钴矿资源得到越来越多的关注。为了科学地评估我国钴矿资源潜力,指导找矿勘查部署工作,立足国内,提高我国钴矿资源的保障能力,笔者2019—2021年开展了9个重点省(自治区)的钴矿资源潜力评价工作。本文从我国钴矿床分布和地质特征角度,先以成矿地质作用为主线,厘定我国找矿预测矿床类型,包括与沉积地质作用有关的风化型、化学沉积型、砂岩型和海底喷流沉积型,与火山地质作用有关的海相火山岩型、陆相火山岩型,与侵入岩浆地质作用有关的岩浆型、矽卡岩型(接触交代型)、热液脉型和斑岩型,与变质地质作用有关的沉积变质型,以及少量与大型变形地质作用有关的变质核杂岩型;进而梳理并总结了各类型钴矿有关的成矿地质体。通过分析我国钴矿的矿床地质特征和时空分布规律,综合地质、物探、化探和遥感信息等预测要素,建立找矿预测模型,并在此基础上圈定找矿远景区,估算资源量。结果表明：我国钴矿包括风化型镍钴矿、海底喷流沉积型铜钴矿、海相火山岩型铁铜钴矿、海相火山岩型块状硫化物铜锌钴矿、岩浆型铜镍钴矿和热液脉型钴矿6种主要找矿预测类型;圈定416个钴矿最...     

极端洪水导致的湖泊水位抬升和氮磷输入增加对苦草(Vallisneria natans)的复合影响

据全球气候变化模型预测,未来极端洪水事件将呈现增多和加剧态势。极端洪水对沉水植物功能性状、生长发育状况及整个生态系统均有深远的影响,研究极端洪水对沉水植物生长发育的影响对理解和预测气候变化过程中水生态系统的变化具有重要意义。本文针对极端洪水事件引起的水位急剧上升和营养负荷量增加双重效应,在实验周期90 d内设置对照(水位保持75 cm)、2种极端洪水条件(水位在第1天从75 cm快速上升至150 cm + NP输入、水位从75 cm逐步上升至150 cm + NP输入)以及水位保持75 cm + NP输入4项处理(后3项处理中营养输入总量相同),研究了极端洪水对沉水植物苦草(Vallisneria natans)生长、繁殖对策及生物量分配的影响,实验过程中还同步监测了浮游植物、附着藻类和水体营养状况(TN和TP)。在苦草的17个测定指标中,只有根生物量分配和有性繁殖分配在4个处理下无明显变化。从水位的单独作用看,相对于营养增加且水位恒定的处理,两种洪水条件(水位急剧上升和逐步上升)均降低了苦草的分株数、叶片数、间隔子数、间隔子总长、最大根长、花果数以及各器官生物量和总生物量,促进了人工基质表面附着藻类的生长。水位急剧上升时,植株对间隔子的生物量投资倾向于最小,而株高和植株对叶的生物量投资倾向于最大。从营养负荷的单独作用来看,相对于对照组,营养增加且水位恒定的处理中水体N浓度显著增加,促进浮游植物和苦草表面附着藻类的生长,但是从二者的Chl.a浓度来看,浮游植物遮光作用相对较大,抑制了苦草叶、根和间隔子的生长,但有性繁殖生物量无明显变化。从水位和营养负荷联合作用的模式来看,水位上升和营养负荷两个环境因素的联合作用会使入湖营养负荷加强水位上升对沉水植物生长的影响效应,二者的联合作用使叶、根、间隔子和有性繁殖生物量均大大降低。因此,极端洪水对沉水植物的不利影响较大,一方面水位抬升会直接影响沉水植物,另一方面会通过浮游植物间接影响沉水植物生长发育。     

基于城市扩张的动态选址模型——以深圳垃圾转运站选址为例

现有的许多选址模型研究,主要集中在对选址算法的改进,而忽略了城市作为复杂地理系统所具备的不确定性和动态发展性对选址结果的影响。这往往导致最终的选址结果在设施投入使用后,无法满足新的需求甚至出现不适应新环境的情况。本文将基于GeoCA(地理元胞自动机)的城市扩张模型引入到传统的Location-allocation选址模型中,构建一个动态的选址模型框架,探索如何将选址结果建立在动态的、科学的城市形态预测基础上,促使选址结果更具有客观性、先见性和更符合可持续发展观,这也正是本研究的重要意义所在。同时,框架中的许多子模型都能够单独被优化,具有高度的可伸缩性,能够自适应于特定区域的选址要求。     

旅游活动与水环境耦合分析 ——以玉龙雪山-丽江盆地为例

玉龙雪山是我国季风海洋型冰川发育最为典型的代表性地区,也是北半球最靠近赤道的现代冰川区.丽江市的部分水源来自于玉龙雪山冰川融水,同时玉龙雪山景区每年吸引着上千万的游客来欣赏现代冰川.旅游活动与水环境息息相关且相互作用,水环境的准确刻画是指导与优化区域旅游活动的基础.以世界著名旅游城市丽江市为例,基于实地采样与数据分析,...