2-羟基-3-丁氧基丙基羟乙基纤维素的制备及温度响应性能研究

为制备出具有良好温度响应性能的多糖基温度响应材料,以羟乙基纤维素(HEC)为亲水性高分子骨架,利用醚化反应将疏水化试剂丁基缩水甘油醚(BGE)接枝到其骨架上,调节疏水基团丁基基团的取代度,使其具有合适的亲水亲油平衡,制备出具有温度响应性的2-羟基-3-丁氧基丙基羟乙基纤维素(HBPEC);运用核磁共振(~1HNMR)对HBPEC进行结构表征,研究了溶剂用量、碱用量、反应温度和反应时间对HBPEC合成的摩尔取代度(MS)和反应效率(RE)的影响。结果表明:HBPEC的最佳反应条件为m(H_2O)∶m(AGU)=6,n(NaOH)∶n(AGU)=1.8,反应温度为90℃,反应时间为9 h;不同取代度的HBPEC有不同的最低临界溶解温度(LCST),且最低临界溶解温度随着取代度的增加而下降,当HBPEC取代度从0.98增加到2.32时,最低临界溶解温度从44.6℃降低到24.1℃。研究表明,本研究中制备出具有温度响应性能的纤维素基功能材料,为功能材料在药物缓释、生物等领域的应用提供了新途径。     

Ice, quakes, and a wobble shake san francisco

The fall meeting of the American Geophysical Union (AGU) in San Francisco last month was bumped to the Moscone Center while the Civic Auditorium, its venue in past years, was being reinforced against earthquakes. And that may have been fitting, given the meeting's focus on sudden events in Earth history: the first moments of fault rupture, repeated outbursts of icebergs during the last ice age, and a shift in the seasons in the middle of this century.     

Catastrophes of every ilk at the geophysics fest

At the annual meeting of the American Geophysics Union (AGU) in San Francisco on 7-11 December, catastrophes came in all sizes. On the molecular level, atmospheric chemists had news about the manmade compounds destroying the ozone shield-and for once the news was good. More earthshaking were signs of long-distance connections among earthquakes. And from farther afield came reports of odd-shaped debris from mini-planet collisions.     

Geophysicists celebrate two satellites, mourn a third

Searching for a common theme in a gathering as diverse as the spring meeting of the American Geophysical Union (AGU) in Baltimore last month might seem futile. But satellites, both natural and artificial, provided some of the meeting's high points. Researchers reported on the first science results from the Clementine spacecraft's 2-month sojourn orbiting the moon, the revealing color of the small moon that accompanies the asteroid lda, and the planned termination of the Magellan spacecraft orbiting Venus.     

淀粉-偶氮苯衍生物接枝共聚物的反相乳液合成及表征

以Span-80为乳化剂,K2S2O8的碱性溶液引发淀粉与偶氮苯衍生物接枝共聚,考察了反应温度、时间、pH值及乳化剂用量对接枝率和接枝效率的影响。结果表明:在反相乳液中应用价廉无毒的K2S2O8的碱性溶液引发接枝共聚反应,可以达到较高的接枝率和接枝效率。当淀粉用量7.00%,[单体]=0.391 mol/L,[K2S2O8]=8.650 mmol/L,[KOH]=0.178 mol/L,乳化剂用量8.02%,反应时间120 min以及反应温度50℃时接枝率和接枝效率分别达最大值69.88%和94.60%。并应用X-ray衍射、热重分析TGA和差热分析DTA等测试手段对接枝共聚物进行了表征,确证了接枝的发生。     

蕙兰一个PEBP家族基因的克隆及生物信息学分析

为了初步探究蕙兰磷脂酰乙醇胺结合蛋白(phosphatidyl ethanolamine-binding proteins, PEBP)基因的特征与功能,以蕙兰花蕾期叶片为材料,利用反转录PCR(RT-PCR)结合cDNA末端快速扩增(RACE)技术克隆基因,使用在线生物信息学工具进行蛋白结构与功能预测,通过R语言和3个在线软件(CodonW、CHIPS和CUSP)分析该基因的密码子偏好性。结果表明,克隆得到的蕙兰PEBP基因包含531 bp长度的开放阅读框(ORF),对应编码氨基酸176个。该基因命名为CfPEBP(登录号MT795710)。生物信息学分析表明,CfPEBP分子式为C₈₈₂H₁₃₆₆N₂₅₄O₂₆₀S₅,分子量为19 848.39 u;等电点为 6.42;具有15个磷酸化位点。CfPEBP蛋白无信号肽结构域,具有PEBP功能域。进化树分析结果表明,CfPEBP蛋白与春兰FT进化距离最近,同源性为100%。分析显示,CfPEBP的密码子偏好性表现较弱;依据同义密码子相对使用度(RSCU)分析较强偏性密码子有GGC、AGA、AGU、AAG、CCA、CUC(RSCU≥2.00)。18个物种PEBP基因RSCU值分析表明,蕙兰HQ164434、文心兰KJ909968、文心兰EU583502、石斛MF063061、香蕉KF853468、牵牛AB154823的密码偏好性较强,均有25个以上RSCU值>1. 00的密码子。PEBP家族基因对于GGC、AGG、AGA、AGC、AGU、UGC、GAG、AAG、UAC、GCC、CCA、CUC的偏好性超过其他密码子。CfPEBP基因在蕙兰盛花期叶中相对表达量最高,花蕾期花蕾和盛花期花葶中表达量次之,其他组织几乎不表达。本研究为蕙兰PEBP家族基因功能的进一步研究提供了基础。     

亚洲璃眼蜱成蜱不同发育期miR-451与MIF表达谱的动态分析

【目的】microRNA （miRNA）作为一类内源性的非编码RNA,仅有18-25 nt,其广泛存在于动植物细胞中,可诱导生物基因沉默,参与细胞生长、发育、基因转录和翻译等诸多生命活动的调控过程。以亚洲璃眼蜱为研究对象,对miR-451及其靶基因（巨噬细胞游走因子, MIF）在相互作用关系进行分析。【方法】参考miR-451成熟体序列（AAA CCG UUA CCA UUA CUG AGU UU）来自研究单元亚洲璃眼蜱高通量测序所获得的结果。根据该成熟体序列设计stem-loop及PCR引物,RT-PCR扩增获得蜱源性miR-451序列;并对不同物种来源的miR-451序列特征进行分析。基因合成方法获得抑制miR-451的dsRNA序列,用于亚洲璃眼蜱饥饿成蜱体内注射。参考美洲钝眼蜱MIF基因（登录号：AF289543.2）,设计亚洲璃眼蜱的特异性实时荧光定量引物,以β-actin作为内参基因,采用SYBR Green real-time RT-PCR方法检测注射dsRNA后亚洲璃眼蜱饥饿成蜱不同发育时间点MIF基因的表达水平,以及miR-451的表达谱特征。【结果】琼脂糖凝胶电泳检测miR-451的PCR产物条带与预期大小一致,为72 nt。不同物种来源的miR-451具有较高的保守性,特别是种子序列极度保守,仅在短尾负鼠miR-451成熟体的19位点处存在A→U的突变。miR-451的RNA干扰实验证实,0-30 h miR-451表达逐渐上调,6 h达到最高值,其拷贝数为1.0×108。随后表达丰度逐渐降低。30 h其表达水平与PBS对照组相同。48-60 h miR-451再次出现一个表达上调微小变化过程。而miR-451抑制后的MIF直到30 h才有表达的上调,42 h达到峰值（拷贝量仅为9.0×103）,此后其表达规模受到抑制,48 h时与PBS对照组水平一致。84 h后表达才逐渐上调,直到90 h达到峰值,并呈现正态分布趋势。【结论】利用RT-PCR获得亚洲璃眼蜱成蜱阶段miR-451序列,生物信息学方法分析了miR-451序列在不同物种间具有较高保守性。miRNA的保守性决定其靶标基因的特异性,因此,以上结果提示miR-451在动物细胞中可能扮演重要的生物学功能,是MIF功能发挥的一个重要调控因子。MIF作为miR-451靶标基因,其功能的实现可能受该miRNA的调控。基于此类推测qPCR及RNA干扰分析表明,miR-451参与了MIF的表达调控。且是一种负调控作用。当miR-451表达量升高时,MIF表达量明显下调。此研究首次证实miR-451在亚洲璃眼蜱成蜱发育阶段的表达是一种普遍现象,且对MIF存在负调控作用。这一研究为后期miR-451参与蜱的免疫应答及miR-451与靶标基因的相互作用机制提供了参考。同时证明,miRNA参与基因功能的调控具有一定的特异性和时序性。     

鞑靼忍冬引种繁育及适应性分析研究

为了丰富宁夏六盘山的观赏植物资源,发展生物多样性,促进六盘山生态体系和产业体系建设,2007年从黑龙江省植物园采集鞑靼忍冬种子,在六盘山进行引种、繁育试验,并在宁夏银川、陕西杨凌等地区进行适应性试验。结果表明,鞑靼忍冬在六盘山地区适应性极强,目前已在六盘山地区、银川市、陕西等地进行大面积推广繁育,并在城市绿化中得到了逐步应用。     

葡萄籽的营养保健功能及开发利用

葡萄籽含有多种生物活性物质,具有极高的营养保健功能,其相关研究已引起广泛关注。综述了葡萄籽主要的生物活性物质葡萄籽原花青素提取物(GSPE)、白藜芦醇、单宁、葡萄籽油及蛋白质的营养保健作用,并总结了葡萄籽在食品、医药及美容工业中的应用进展,旨在促进葡萄籽在更多领域的开发利用。     

Goals and Trends of Research in Geology and Geography

Summarizing in a few words the essence of the preceding analysis of goals and trends in research in Geology and Geography, we may say that the goal in Geology is a knowledge and understanding of the earth and of its history. In Geography it is a knowledge and understanding of the natural and human environments, to the end that they may best be utilized toward better living in the broadest sense. Trends in research in these sciences that seem not altogether desirable are those toward overorganization of research and overdirection from others than the ones who are to do the work; toward indiscriminate fact-gathering; toward lessening of critical analysis of, and discussion of, papers given at meetings and of the published results; and toward premature publication and excessive volume of publications resulting from the prevailing practice of soliciting papers for scientific meetings. Changes in methods of financing of research resulting from a great decrease in endowment incomes are noted, together with a strong tendency to look toward the Federal Government for the financing of university research, in spite of the obvious dangers to university freedom which such financing involves.     

Mass mortality and its environmental and evolutionary consequences

The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10(2) or 10(3) years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The data indicate that at the end of Cretaceous, when a high proportion of the ocean's planktic organisms were eliminated, an associated reduction in productivity led to a partial transfer of dissolved carbon dioxide from the oceans to the atmosphere. This resulted in a large increase of the atmospheric carbon dioxide during the next 50,000 years, which is believed to have caused a temperature rise revealed by the oxygen-isotope data. The lowermost Tertiary sediments at site 524 include fossils with Cretaceous affinities, which may include both reworked individuals and some forms that survived for a while after the catastrophe. Our data indicate that many of the Cretaceous pelagic organisms became extinct over a period of a few tens of thousands of years, and do not contradict the scenario of cometary impact as a cause of mass mortality in the oceans, as suggested by an iridium anomaly at the Cretaceous-Tertiary boundary.     

Effects of fish and plankton and lake temperature and mixing depth

A comparative study of small temperate lakes (<20 square kilometers) indicates that the mixing depth or epilimnion is directly related to light penetration measured as Secchi depth. Clearer lakes have deeper mixing depths. This relation is the result of greater penetration of incident solar radiation in lakes and enclosures with high water clarity. Data show that light penetration is largely a function of size distribution and biomass of algae as indicated by a relation between the index of plankton size distribution (slope) and Secchi depth. Larger or steeper slopes (indicative of communities dominated by small plankton) are associated with shallower Secchi depth. In lakes with high abundances of planktivorous fish, water clarity or light penetration is reduced because large zooplankton, which feed on small algae, are reduced by fish predation. The net effect is a shallower mixing depth, lower metalimnetic temperature and lower heat content in the water column. Consequently, the biomass and size distribution of plankton can change the thermal structure and heat content of small lakes by modifying light penetration.     

压缩炭化杨木的微观结构与化学成分

研究压缩、炭化过程中木材结构与化学成分的变化对压缩炭化木的应用有重要意义。利用扫描电镜、扫描电镜X射线能谱和红外光谱分析研究了杨木经压缩、炭化的微观结构和木材的化学成分变化。研究发现：意杨Populuse euratnericoIta经过压缩、炭化后,细胞腔变小,胞壁距离减小,胞壁距离最大分别缩小56．94％和53．34％,但细胞壁本身仍然保持了其完整性：心边材各元素的变化趋势一致,炭元素上升,氧元素下降,以边材为例,素材O／C为1．76,压缩、炭化处理后分别为1．65,1．45;杨木在热压和高温炭化过程中,纤维素的降解,使C—H伸缩振动吸收峰强度下降．并发生了一定的位移,半纤维素降解使C-0伸缩振动吸收峰强度降低。木质素苯环和酚醚键C-0-C的伸缩振动吸收峰的变化说明木质素也发生了化学反应．炭化后的心材在波数2853cm。附近出现了明显的振动．说明木材内部复杂的化学反应产生了新的化学基团。图9表1参15     

Science and product

Much of what needs to be changed in U.S. industry involves close ties to manufacturing, design for manufacturability, a rapid design cycle, and up-to-date technical knowledge on the part of the engineers themselves. Being up-to-date requires conscious company effort. Traveling to meetings, reading the technical literature, and being a part of the engineering community are necessities if we are to compete with others who make these efforts and are thus better able to incorporate technical change rapidly into their own products. Outside the product improvement cycle, a research (as opposed to development) organization in industry must have close ties to development and manufacturing in order to succeed. With these close ties, researchers can understand the progress of the cycle and can introduce new steps at the appropriate time and in an acceptable form. A research organization that surmounts the internal barriers and becomes an accepted contributor to the development and manufacturing process can, because of its greater technical depth, its scientific knowledge, and its close ties with the university world, become a forceful initiator of progress. It is more difficult, in our opinion, to make these contributions from a university base and from government laboratories as they are now constituted. Much has been said by industry and government leaders about reforming the educational system and strengthening the national science base-things that help build a strong foundation. A strong science base supplies a vast storehouse of new ideas, and a good educational system provides engineers and manufacturing workers with knowledge; but strength here cannot make up for inadequacies in the functioning of the development and manufacturing cycle. The United States must learn to succeed, not only in the ladder type of innovation in which a wholly new idea from science creates a wholly new product (the science-dominated process at which we have succeeded in the past), but also in the rapid, cyclical, engineer-dominated process of incremental product improvement. Neither process is a substitute for the other; we need both.     

2013年国内外稻米市场形势分析及展望

2013年1-10月,中国稻谷市场维持稳中略跌态势,南方籼米市场受到进口和“镉超标”事件双重影响,持续疲软.国际米价在恢复性上涨后出现持续下跌,涨跌的诱因是主要贸易国政策调整.2013年1-8月中国稻米出口增加、进口减少.预计后市,国内稻谷有望再获丰收,稻谷最低收购价政策将面临考验,大米价格将出现分化,粳稻期货上市将为市场对粮源调节起决定性作用创造条件.短期内,国际大米价格将以弱势运行为主.     

巴彦淖尔市经济作物病虫普查及防控对策

经济作物的种植对巴彦淖尔市的农业生产起着极其重要的支柱作用,左右着全市农业生产形势。但是,近年来经济作物种植的种类、面积、布局、种植方式的改变,使病虫害发生情况有了很大变化,有的新发生病虫危害已很严重。为有效地控制危害,保证全市经济作物特别是粮、油、瓜类、蔬菜等作物的安全生产,更好地发挥自然优势,2011-2012年经过2年的全市大面积经济作物普查,为防控提供可靠依据。普查中共对种植的13种经济作物进行了调查观察,共查到病虫48种,同时对主要发生的10种病虫进行了系统观察,初步摸清了其发生规律。     

漳台农业交流合作的实践与成效

随着中央大力推进海峡两岸合作与交流,漳州作为两岸现代农业交流合作的示范区,对于海峡西岸经济区的建设具有十分重要的作用。基于加强闽台农业合作的视角,该文从农业合作载体、农业合作交流平台、农业产业对接、农业经营管理合作模式、农业合作投资环境等方面对于漳台农业交流合作的发展概括进行了总结,为其他地区对台交流合作提供了借鉴。     

西北军政委员会与建国初期的西北农林建设

西北军政委员会是新中国成立初期设立于西北的最高政权机关,虽然它主要是为实施军事管制、建立政治社会秩序而设立的,但是作为军政合一的政权组织。西北军政委员会在建国初期,为挽救西北地区破败的农业经济,无论是对该区农业经济、还是与之相辅相成的林业经济发展,都提出了诸多的保障措施,并制定了一系列有利于农林经济发展的方针政策,在为建国初期的西北农林建设和发展做出了积极而有力的贡献的同时,也为长远的西北农林业的发展打下了良好基础。     

谈诗情画意与中国古典园林

诗情画意是中国传统文化的重要组成部分,在中国古典园林中得到充分体现;而中国古典园林具有文化的属性,是诗和画的统一体。诗画对园林,无论是在形式还是内涵上都有着深刻影响;反过来,园林在诗画中也时常有反映。园林、诗和画具有共同的追求,即所谓的"意境"。中国古典园林和诗画打通各艺术范畴甚至人的感官隔阂,达到审美体验的互渗交融。