衡水市蔬菜农药残留的危害分析与对策探讨

从农药残留对人体健康的危害出发，分析了衡水市目前蔬菜农药残留的现状和产生污染的原因，在此基础上提出了减少农药残留的对策．     

A terminal Pleistocene child cremation and residential structure from eastern Beringia

The dearth of human remains and residential sites has constrained inquiry into Beringian lifeways at the transition of the late Pleistocene-early Holocene. We report on human skeletal remains and a residential structure from central Alaska dated to ~11,500 calendar years ago. The remains are from a ~3-year-old child who was cremated in a pit within a semisubterranean house. The burial-cremation and house have exceptional integrity and preservation and exhibit similarities and differences to both Siberian Upper Paleolithic and North American Paleoindian features.     

烤烟根残体浸提液对土壤酶活性的影响

[目的]为探讨烤烟根残体在烤烟连作障碍方面的作用和机理。[方法]采用室内模拟试验和化学分析方法,研究根残体浸提液对土壤酶活性的影响。[结果]烤烟根残体浸提液对土壤氧化还原酶活性有激活作用,培养25 d后以添加45%处理的作用最明显,但随着培养时间的延长过氧化氢酶和多酚氧化酶活性与对照无显著差异。根残体水浸提和培养时间均影响脲酶、蔗糖酶、磷酸酶活性。随着培养时间的延长,土壤脲酶活性明显增强,蔗糖酶活性呈下降趋势,3种磷酸酶活性均降低;随着根残体浸提液浓度的增加,脲酶活性增加越明显,土壤蔗糖酶活性降低越显著,土壤酸性磷酸酶活性抑制作用增强。[结论]根残体影响土壤中主要酶活性,间接促进或降低土壤中养分含量的变化,从而影响烤烟的生长发育、产量与品质。     

藻类吸附缓解稻田重金属污染的研究

采用盆栽和稻田污染模拟试验,研究了藻类吸附对稻田土壤中重金属和稻谷中重金属残留的影响。藻静态吸附试验结果表明：1 g普通小球藻吸附Cd、Hg和Cr的能力分别为27.60、17.94和22.52 mg/g·h,椭圆小球藻和梅尼小环藻对重金属也有很强的吸附能力;投放普通小球藻、椭圆小球藻和梅尼小环藻的盆栽试验表明,稻谷Hg、Cd和Cr残留比未投放藻的降低76.53%、65.71和53.57%;Cd污染稻田模拟试验表明,有藻田的稻谷Cd残留比无藻田的降低76.47%,达到国家标准要求。可见,藻对重金属的吸附能力可以在稻田中发挥良好作用,由于藻的吸附作用,3种重金属在稻谷中的残留显著下降。     

城市设计中后工业化消极遗迹的文化再生

在城市发展不断更新的背景下,解析了文化循环体系和城市更新中的循环效应,强调应以工业遗址为载体,延续传统文化,将后工业化时代的消极遗迹转变为适应现代人生活发展的现代文明。以北京"798"为例,介绍了其发展历程和现状,结合场所精神,阐释了文化创意园区与工业遗址再利用的现实意义。认为文化创意不仅延长了文化脉络,更加在工业遗址的历史长河中重新找到灵感,以"触媒"的形式转变消极景观在城市更新中的作用,提高经济价值、社会文化价值、文化有效循环价值。     

Orangutan death and scavenging by pigs

Pongid remains are rarely recovered from tropical rain forests. Observations of a Bornean bearded pig (Sus barbatus) scavenging an orangutan (Pongo pygmaeus) carcass and the recovery of an orangutan skull fragment corroborates evidence from Africa and suggests that the scavenging of wild pigs may play an important role in the destruction of pongid remains.     

西安曲江池遗址公园修复与保留对城市景观的影响

重点论述了西安曲江池遗址公园修复与保留对城市景观的影响,提出利用文化遗址推进城市景观发展的主张,并以西安曲江池遗址公园对城市景观的利弊进行分析,得出要利用文化遗址塑造城市景观新面貌,从而探讨文化遗址在城市景观中的重要意义。     

Australopithecus garhi: a new species of early hominid from Ethiopia

The lack of an adequate hominid fossil record in eastern Africa between 2 and 3 million years ago (Ma) has hampered investigations of early hominid phylogeny. Discovery of 2.5 Ma hominid cranial and dental remains from the Hata beds of Ethiopia's Middle Awash allows recognition of a new species of Australopithecus. This species is descended from Australopithecus afarensis and is a candidate ancestor for early Homo. Contemporary postcranial remains feature a derived humanlike humeral/femoral ratio and an apelike upper arm-to-lower arm ratio.     

河南仰韶村文化遗迹点分布特征研究

针对小尺度遗址区内遗迹点空间分布特征研究较少的问题,以河南仰韶村文化遗址为研究区,采用GIS空间分析方法,提取遗迹点的环境参数,统计分析得出其主要特征,并计算得出遗迹点的分布结构和地理集中度。结果显示,遗迹点高程一般为590~650 m,坡度为1.7°~5.1°,坡向值为112.5°~202.5°,距河流距离为250~350 m。这表明古人类选择生产生活地址时,通常选择坡度平缓、坡向以东南和南朝向为主、地势具有一定高度且距离河流稍近的区域。遗迹点空间分布结构类型为凝聚型,且地理集中度高,这表明古人类倾向于群居生活。     

Fecal pellets: role in sedimentation of pelagic diatoms

Membrane-enclosed fecal pellets of planktonic herbivores were sampled at several depths in the Baltic Sea (459 meters deep) and off Portugal (4000 meters deep) by means of a Simonsen multinet. Pellets contained mainly empty shells of planktonic diatoms and silicoflagellates. Two kinds of fecal pellets were found, those with the remains of one species (for example, Thalassiosira baltica) and those with the remains of several species (for example, Chaetoceros, Achnanthes, and Thalassiosira). Siliceous skeletons were protected from dissolution during settling by a membrane around the pellet.     

农药降解与残留分析中数学模型的应用

文章介绍了目前在农药残留分析中常用的定量研究农药降解规律的6类数学模型,给出了各类模型在实际问题中的应用,比较了它们的优缺点,分析了各类模型对于预测农药残留量的作用。     

Chronology of guitarrero cave, peru

Dating by accelerator mass spectrometry of wooden artifacts, cord, and charcoal samples from Guitarrero Cave, Peru, supports the antiquity of South America's earliest textiles and other perishable remains. The new dates are consistent with those obtained from disintegration counters and leave little doubt about the integrity of the lower Preceramic layers and their early cultivars. Re-evaluation of the mode of deposition suggests that most of the remains resulted from short-term use of the cave in the eighth millennium B.C., with a possible brief human visit as early as 12,560 years ago.     

Structure of a DNA glycosylase searching for lesions

DNA glycosylases must interrogate millions of base pairs of undamaged DNA in order to locate and then excise one damaged nucleobase. The nature of this search process remains poorly understood. Here we report the use of disulfide cross-linking (DXL) technology to obtain structures of a bacterial DNA glycosylase, MutM, interrogating undamaged DNA. These structures, solved to 2.0 angstrom resolution, reveal the nature of the search process: The protein inserts a probe residue into the helical stack and severely buckles the target base pair, which remains intrahelical. MutM therefore actively interrogates the intact DNA helix while searching for damage.     

The Escherichia coli replisome is inherently DNA damage tolerant

The Escherichia coli DNA replication machinery must frequently overcome template lesions under normal growth conditions. Yet, the outcome of a collision between the replisome and a leading-strand template lesion remains poorly understood. Here, we demonstrate that a single, site-specific, cyclobutane pyrimidine dimer leading-strand template lesion provides only a transient block to fork progression in vitro. The replisome remains stably associated with the fork after collision with the lesion. Leading-strand synthesis is then reinitiated downstream of the damage in a reaction that is dependent on the primase, DnaG, but independent of any of the known replication-restart proteins. These observations reveal that the replisome can tolerate leading-strand template lesions without dissociating by synthesizing the leading strand discontinuously.     

小河西文化生业模式初探

小河西文化是西辽河流域新石器时代较早阶段的文化遗存。通过对小河西文化的气候与环境、聚落、生产生活工具、动植物遗存和原始农业的分析来看,小河西文化的生业模式以渔猎采集为主,辅之以简单的农业为补充,其原始农业已经处于萌芽阶段。     

Environment and behavior of 2.5-million-year-old Bouri hominids

The Hata Member of the Bouri Formation is defined for Pliocene sedimentary outcrops in the Middle Awash Valley, Ethiopia. The Hata Member is dated to 2.5 million years ago and has produced a new species of Australopithecus and hominid postcranial remains not currently assigned to species. Spatially associated zooarchaeological remains show that hominids acquired meat and marrow by 2.5 million years ago and that they are the near contemporary of Oldowan artifacts at nearby Gona. The combined evidence suggests that behavioral changes associated with lithic technology and enhanced carnivory may have been coincident with the emergence of the Homo clade from Australopithecus afarensis in eastern Africa.     

大蒜叶斑病(Cladosporium allii)的研究Ⅴ．病残体的残存

 病残体处于不同相对湿度(RH)下存活期不同.浸没水中和处于RH100%的存活期不超过1个月,RH90%的不超过7个月,RH75%的不超过14个月,RH65%的不超过34个月,在RH50%～10%的存活期可达77个月,即6年半,病残体上休眠分生孢子和菌丝体复苏生长过程是:休眠孢子培养果一大开始萌发.第5天产生孢子梗及孢子.第12天未见新孢子产生,成熟孢子开给脱落,菌丝萎缩.第6～9天是产生孢子高峰期,一个孢子可新产生孢子15个,最多达36个,一个孢子梗可新生孢子4个,最多达6个.     

冰温贮藏后"大久保"桃不同出库方式对果实细胞壁组分及相关酶活性的影响

以大久保桃(Prunus persicaL.Batsch)为试验材料,研究了不同出库方式对冰温贮藏后果实细胞壁组分以及相关酶活性的影响。研究结果表明:以低温冷链方式出库的果实在货架期期间好果率高并且出库后14 d果实硬度仍保持在12.43 kg/cm2,而缓慢升温和变温处理果实的硬度分别下降到3.45和3.33 kg/cm2,直接出库(对照)的硬度则降至2.98 kg/cm2。这可能是由于低温冷链出库降低了果实中多聚半乳糖醛酸酶(PG)和果胶甲酯酶(PE)活性,使得果实中可溶性果胶和松弛结合型多糖的含量变低,从而维持了较高的果实硬度。但低温冷链出库对果实中多酚氧化酶和过氧化物酶活性影响不大。     

南朝长江流域的宫观碑记与道教造像——南朝十三通宫观碑记的梳理与讨论

长江流域是南北朝时期道教发展的重要地区,但宫观造像方面却遗存难考、史料不足。从现有考古成果和文献看,目前只能收集到十三通南朝宫观碑记。这些碑记记载了宫观中的神祗与造像,同时也涉及到一些宫观造像的形制材料。这些材料反映出当时道教造像的存在形态,即：南朝时期长江流域已经出现了道教神仙的供奉仪式,但南朝宫观中普遍不设置神像。     

凤眼莲残体对城市河道有机物污染的影响

[目的]研究凤眼莲残体对城市河道有机物的影响。[方法]监测调查污染河道内凤眼莲死亡前后水体有机污染主要指标的变化,探讨凤眼莲残体对污染河流有机污染的影响。[结果]在调查河段,凤眼莲的腐烂分解主要发生在生长后第2年2～4月,对河流水体的有机污染也主要集中在此期间;凤眼莲残体导致水体高锰酸钾指数（CODMn）、5d生化需氧量（BOD5）略有增加,在4月份各监测点的CODMn、BOD5均达年度最大值;凤眼莲死亡分解对下游虽有一定的影响,但影响并不显著（P〉0.05）。[结论]该研究为进一步了解凤眼莲死亡引起的二次污染状况提供参考。