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四川慈竹生理生化指标对SO_2胁迫的响应
No full text【目的】研究SO_2胁迫下四川慈竹(Neosinocalamus affinis)的抗性及净化能力。【方法】通过人工模拟熏气法研究SO_2胁迫下慈竹叶片形态和生理生化指标变化,SO_2处理设置为CK(自然状态,低于3 mg/m~3 SO_2)、S1(30 mg/m~3 SO_2)、S2(60 mg/m~3 SO_2)。【结果】(1)慈竹叶片的叶脉在初期表现为点状伤斑而在后期为条状伤斑,受害程度表现为S2>S1>CK,且SO_2浓度越高受害症状出现越早,受害程度越大;(2)SO_2胁迫在时间上的持续和浓度上的增加,导致了慈竹叶绿素总量的增加;(3)SO_2胁迫30 d后导致了慈竹净光合速率、气孔导度、蒸腾速率升高,且在S1时达到峰值,但在S2处下降;慈竹胞间CO_2浓度随SO_2浓度升高而降低;(4)慈竹叶的丙二醛、可溶性糖、脯氨酸(0~20 d)、可溶性蛋白、超氧化物歧化酶、过氧化物酶、过氧化氢酶、叶片硫含量均随SO_2胁迫持续和浓度升高而升高,其中在30 d时,SO_2处理下慈竹脯氨酸含量明显低于初始值和CK。【结论】慈竹能通过调节自身保护机制来应对低浓度SO_2的逆境胁迫并维持正常生长,该结果可为城市SO_2污染(雾霾、汽车尾气等)治理和城市园林绿化提供基础数据与理论依据
阆中农林复合系统不同模式下土壤温度与湿度变化分析
No full text本文通过在农林复合系统中,4种不同模式(核桃+川明参(C)、核桃+桔梗(J)和核桃+藿香(H),以核桃纯林作为对照),进行了土壤的理化性质、温度与湿度的测定,并对比,得出以下结论:在4种农林药模式下1、土壤上层土壤理化性质与下层土壤理化性质的差异不明显;2、各模式间温度差异不显著,而时间效应以及时间和各处理间的交互效应达极显著水平;3、各模式间相对湿度不存在显著差异,但时间效应以及时间和处理交互效应达极显著水平
土壤碳氮磷化学计量比时空格局及影响因素研究进展
No full text土壤碳氮磷化学计量比(C:N:P)可以反映有机质质量和含量,其研究对于理解生态学过程和生态系统对气候变化与干扰的响应十分重要.综述了土壤C:N:P随土层深度、海拔、纬度和演替梯度上的时空变化格局及其影响因素:土壤N:P和C:P随土壤深度而递减,但土壤C:N随土层深度的变化趋势还有争论;土壤C:N随海拔变化并非呈现简单的线性关系而是复杂多变的;在全球和区域尺度上,土壤C:N随纬度增加而增大,而土壤C:P则减小;在演替过程中,受到所选择的演替阶段及其时间序列范围和环境特征等因素影响,土壤C:N:P的演替变化趋势存在明显的争论.综合分析表明:1)对土壤C:N关注多,而N:P与C:P研究较贫乏;2)土壤C:N:P的时空变化格局规律还不完全清楚;3)土壤C:N:P受气候、土壤、植被以及人为活动的影响是清楚的,但其机制并不清楚.因此,未来需要更多地聚焦土壤N:P与C:P的变化格局规律,关注土壤C:N:P变异的多种(生物、物理与化学)作用机制研究及其与生态系统结构和功能动态变化的关系,并通过整合植物-凋落物-土壤系统的化学计量学研究,为深入揭示营养元素的生物化学耦合循环规律提供新证据
四川省森林植被碳储量及碳密度估算
No full text基于第8次全国森林资源连续清查数据,采用生物量扩展因子法,对四川省森林植被资源的碳储量及碳密度进行估算及分析。结果表明:截止2013年,四川省森林植被总碳储量为729.05 Mt,森林植被平均碳密度为43.26 t/hm~2,林分生物量为1 331.66 Mt,林分碳储量为670.09 Mt,林分平均碳密度为56.84 t/hm~2;针叶林碳储量在四川省森林各林型碳储量中贡献最大,成过熟林在不同林龄结构碳储量中占有重要地位;幼龄林及中龄林面积占森林林分面积的42.67%,说明四川省森林植被资源趋于年轻化,具有巨大的发展潜力,随着林龄的增长,林分碳密度与各龄组中单位蓄积量呈逐渐增长趋势
云南杨梅碳、氮、磷化学计量特征
No full text碳(C)、氮(N)、磷(P)在植物生长和各种生理调节机能中发挥着重要作用。为研究云南灌丛生态系统C、N、P含量之间的关系以及植物生物量、土壤C、N、P含量与植物C、N、P含量的相互影响,该研究采用样地调查的方法,在云南省云南杨梅(Myrica nana)灌丛主要分布区设立了29个样地,通过测量样地中云南杨梅灌丛C、N、P含量,系统分析了云南杨梅C、N、P的计量规律。结果显示:1)研究区域云南杨梅根、茎、叶的C、N、P含量的平均值分别是45.94%、0.54%、0.03%,46.32%、0.58%、0.03%和49.05%、1.70%、0.06%(干质量),其中叶的C、N、P含量均显著高于茎和根。在根中C:N:P为1 531:18:1,在茎中C:N:P为1 544:19:1,而在叶中C:N:P为818:10:1,反映了云南杨梅不同部位元素计量不同的分配关系;2)云南杨梅叶片中C含量和N:P值随生物量的增加而降低,但只有叶片C含量与生物量的相关关系极显著,而N:P值与生物量的相关关系不显著。叶片中N含量和P含量随生物量的增加而升高,其中P含量与生物量的相关关系显著,N含量与生物量的相关关系不显著。云南杨梅叶的N:P(34.2)明显大于8,说明P是云南杨梅生长的限制因素。3)根的C、N、P含量与土壤中的P含量都有显著的相关性,其中N、P为极显著正相关,C为显著负相关;茎的C含量与土壤的C、N、P含量都显著负相关,且N、P含量的相关性极显著,而茎的P含量与土壤中的P含量极显著正相关;叶的P含量与土壤的C、N、P含量都极显著正相关,叶的C含量则与土壤的P含量极显著负相关。该研究结果可为西南高原灌丛生态系统的研究提供数据支持
A one pot three-component reaction for the preparation of dihydroquinolines with two different ketones and aromatic amines
No full textA three component reaction with two different ketones and aromatic amines was firstly investigated. The difference in reactivity between ordinary ketones and ketone esters allowed for the production of 1,2-DHQs efficiently. The possible Skraup reaction with 2 equiv. of the same ketones was prohibited due to the fast formation of imines
Electromagnetic Wave Absorption Coating Material with Self-Healing Properties
No full textElectromagnetic wave absorption coatings can effectively minimize electromagnetic radiation and are widely used in the military and civil field. However, even small scratches on the coating can lead to a large decline of absorption ability and bring serious consequences. To enhance the lifetime of electromagnetic wave absorbing coating, a kind of self-healing electromagnetic wave absorbing coating is developed by introducing host-guest interactions between the absorbing fillers and polymer matrix. After being damaged, the cracks on this coating can be healed completely with the aid of small amounts of water. Simultaneously, the electromagnetic absorbing ability of the coating is restored along with the self-healing process
Copper-Catalyzed Enantioselective Aminoboration of Styrenes with Chiral Sulfoxide Phosphine Ligand
No full textTo date, copper catalysis has become an attractive approach to access multifunctional alkylborons through borylative coupling processes, many important protocols such as carboboration, stannylboration and aminoboration were developed. Among these methods, however, there is no report involving enantioselective aminoboration of simple styrene substrates, which can generate a class of useful chiral compounds. In this work, an enantioselective Cu-catalyzed aminoboration of styrenes by using a chiral sulfoxide-phosphine (SOP) ligand was developed, chiral beta-aminoalkylboranes were obtained in satisfied yields and ee values, and these products can be readily converted to a class of valuable beta-hydroxylalkylamines. A general procedure for the aminoboration of styrenes is as following: in glove box, CuCl (0.02 mmol), chiral sulfoxide phosphine L1 (0.022 mmol) and 2.0 mL of dried tetrahydrofuran were added into a flame-dried tube, the resolved solution was stirred for 30 min at room temperature, then bis(pinacolato) diboron (B(2)pin(2)) (0.3 mmol), t-BuOLi (0.6 mmol) and styrene (0.2 mmol) were added. The tube was taken out of the glove box and cooled to 0 degrees C. Electrophilic amination reagent, O-benzoyl-N,Ndibenzylhydroxylamine (2a, 0.3 mmol), was dissolved in 1.0 mL of ethyl acetate and added to the mixture, the resolved mixture was stirred at 0 degrees C for 24 h. The crude product was filtered through a celite pad, concentrated and oxidized by NaBO3 center dot 4H(2)O. The mixture was extracted three times with ethyl acetate, concentrated and purified with silica gel chromatography to give the desired beta-hydroxylalkylamines, the enantioselective excess of products were determined by chiral HPLC analysis. Broad substrate scope which related to steric and electronic effect were compatible in this catalysis under the standard conditions. To demonstrate the utility of this method, a gram scale experiment was performed and the desired product was obtained in 92% isolated yield and 90% ee. The benzyl group of products can be readily removed via a Pd/C-catalyzed hydrogenation process and the corresponding product with a free amino group in excellent yield (95%)
Kinetic resolution of indolines through reductive amination of aldehydes by chiral Bronsted acid
No full textWe have developed a highly efficient and practical strategy for the kinetic resolution of indoline derivatives, involving a chiral Bronsted acid-catalyzed iminium ion formation and asymmetric transfer hydrogenation cascade process. The kinetic resolution allows the synthesis of 2-substituted N-benzylindolines in good yields with moderate to excellent enantioselectivities. (C) 2017 Elsevier Ltd. All rights reserved
Circulating Tumor DNA Mutation Profiling by Targeted Next Generation Sequencing Provides Guidance for Personalized Treatments in Multiple Cancer Types
No full textCancer is a disease of complex genetic alterations, and comprehensive genetic diagnosis is beneficial to match each patient to appropriate therapy. However, acquisition of representative tumor samples is invasive and sometimes impossible. Circulating tumor DNA (ctDNA) is a promising tool to use as a non-invasive biomarker for cancer mutation profiling. Here we implemented targeted next generation sequencing (NGS) with a customized gene panel of 382 cancer-relevant genes on 605 ctDNA samples in multiple cancer types. Overall, tumor-specific mutations were identified in 87% of ctDNA samples, with mutation spectra highly concordant with their matched tumor tissues. 71% of patients had at least one clinically-actionable mutation, 76% of which have suggested drugs approved or in clinical trials. In particular, our study reveals a unique mutation spectrum in Chinese lung cancer patients which could be used to guide treatment decisions and monitor drug-resistant mutations. Taken together, our study demonstrated the feasibility of clinically-useful targeted NGS-based ctDNA mutation profiling to guide treatment decisions in cancer