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Relay-intercropping soybean with maize maintains soil fertility and increases nitrogen recovery efficiency by reducing nitrogen input 被引量:11
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作者 Qing Du Li Zhou +11 位作者 Ping Chen Xiaoming liu Chun Song Feng Yang Xiaochun Wang weiguo liu Xin Sun Junbo Du Jiang liu Kai Shu Wenyu Yang Taiwen Yong 《The Crop Journal》 SCIE CAS CSCD 2020年第1期140-152,共13页
Optimized nitrogen(N)management can increase N-use efficiency in intercropping systems.Legume-nonlegume intercropping systems can reduce N input by exploiting biological N fixation by legumes.Measurement of N utilizat... Optimized nitrogen(N)management can increase N-use efficiency in intercropping systems.Legume-nonlegume intercropping systems can reduce N input by exploiting biological N fixation by legumes.Measurement of N utilization can help in dissecting the mechanisms underlying N uptake and utilization in legume-nonlegume intercropping systems.An experiment was performed with three planting patterns:monoculture maize(MM),monoculture soybean(SS),and maize-soybean relay intercropping(IMS),and three N application levels:zero N(NN),reduced N(RN),and conventional N(CN)to investigate crop N uptake and utilization characteristics.N recovery efficiency and 15N recovery rate of crops were higher under RN than under CN,and those under RN were higher under intercropping than under the corresponding monocultures.Compared with MM,IMS showed a lower soil N-dependent rate(SNDR)in 2012.However,the SNDR of MM rapidly declined from 86.8%in 2012 to 49.4%in 2014,whereas that of IMS declined slowly from 75.4%in 2012 to 69.4%in 2014.The interspecific N competition rate(NCRms)was higher under RN than under CN,and increased yearly.Soybean nodule dry weight and nitrogenase activities were respectively 34.2%and 12.5%higher under intercropping than in monoculture at the beginning seed stage.The amount(Ndfa)and ratio(%Ndfa)of soybean N2 fixation were significantly greater under IS than under SS.In conclusion,N fertilizer was more efficiently used under RN than under CN;in particular,the relay intercropping system promoted N fertilizer utilization in comparison with the corresponding monocultures.An intercropping system helps to maintain soil fertility because interspecific N competition promotes biological N fixation by soybean by reducing N input.Thus,a maize-soybean relay intercropping system with reduced N application is sustainable and environmentally friendly. 展开更多
关键词 Maize-soybean relay intercropping Reduced nitrogen Biological nitrogen fixation Nitrogen recovery efficiency Soil nitrogen dependent rate
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Influence factors of methane hydrate formation from ice:Temperature,pressure and SDS surfactant 被引量:5
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作者 weiguo liu Yanghui Li Xiaohu Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2019年第2期405-410,共6页
A series of experiments of forming hydrate from ice powders in different conditions have been carried out with constant volume method to evaluate the influence factors such as pressure, temperature, and SDS surfactant... A series of experiments of forming hydrate from ice powders in different conditions have been carried out with constant volume method to evaluate the influence factors such as pressure, temperature, and SDS surfactant. The change of temperature and pressure were collected as a function of elapsed time, which were used to calculate the gas consumption and hydrate saturation during hydrate formation(pVT method). Based on the experimental results and the analysis, it is concluded that:(1) Both initial pressure and temperature have effect on the hydrate formation and temperature plays a more important role in the process;(2) heating and secondary pressurization will promote the gas hydrate formation and enhance the hydrate saturation as a result. Meanwhile, the promotion of heating seems to be more obvious than that of secondary pressurization;(3) different concentrations of SDS surfactant have clearly influence on the saturation of gas hydrate and there is an optimal concentration to promote the hydrate formation. 展开更多
关键词 METHANE HYDRATE ICE Heating Secondary PRESSURIZATION SURFACTANT
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Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau, China 被引量:4
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作者 Yuan YAO weiguo liu 《Journal of Arid Land》 SCIE CSCD 2014年第5期592-600,共9页
The hydrogen isotopic composition of plant leaf wax(δDwax) is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological fact... The hydrogen isotopic composition of plant leaf wax(δDwax) is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water(δDwater) and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content(SWC)(R^2=0.9166), and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha(GCh) and Gahai(GH) transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC(R^2=0.6835), which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau. 展开更多
关键词 hydrogen isotope D-enrichment soil water content northeast Qinghai-Tibetan Plateau
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Granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells for the treatment of ischemic stroke 被引量:2
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作者 Xingjian Lin Yingdong Zhang +4 位作者 weiguo liu Jingde Dong Jie Lu Qing Di Jingping Shi 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第16期1220-1227,共8页
Adult, male, Sprague-Dawley rats were injected with granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells (GM-CSF-BMSCs) into the ischemic boundary zone at 24 hours after onset of mi... Adult, male, Sprague-Dawley rats were injected with granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells (GM-CSF-BMSCs) into the ischemic boundary zone at 24 hours after onset of middle cerebral artery occlusion. Results showed reduced infarct volume, decreased number of apoptotic cells, improved neurological functions, increased angiogenic factor expression, and increased vascular density in the ischemic boundary zone in rats that underwent GM-CSF-BMSCs transplantation compared with the BMSCs group. Experimental findings suggested that GM-CSF-BMSCs could serve as a potential therapeutic strategy for ischemic stroke and are superior to BMSCs alone. 展开更多
关键词 bone marrow stromal cells granulocyte-macrophage colony-stimulating factor gene transfection ischemic stroke TRANSPLANTATION stem cells neural regeneration
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Adsorption isotherms and kinetic characteristics of methane on block anthracite over a wide pressure range 被引量:2
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作者 Wanli Xing Yongchen Song +4 位作者 Yi Zhang weiguo liu Lanlan Jiang Yanghui Li Yuechao Zhao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2015年第2期245-256,共12页
It is important to quantitatively understand the methane adsorption and transport mechanism in coal for an evaluation of the reserves and for its production forecast. In this work, a block coal sample was chosen to pe... It is important to quantitatively understand the methane adsorption and transport mechanism in coal for an evaluation of the reserves and for its production forecast. In this work, a block coal sample was chosen to perform the CH_4 adsorption experiments using the gravimetric method at temperatures of 293.60 K, 311.26 K, 332.98 K and 352.55 K and pressures up to 19 MPa. The excess adsorption capacity of CH_4 in dry block anthracite increased, followed by a sequence decrease with the increasing pressure. High temperature restrained the growth of the excess adsorption due to that the adsorption is an intrinsically physical and exothermic process. The excess adsorption peak decreased slowly with the increase of temperature and intersected at a pressure of more than 18 MPa; meanwhile, the pressure at the excess adsorption peak increased. The existing correlations were exanfined in terms of density rather than pressure. The DR+k correlation, with an average relative deviation of 4-0.51%, fitted our data better than the others, with an average relative deviation of up to 2.29%. The transportation characteristics of CH_4 adsorption was also investigated in this study, including the adsorption rate and diffusion in block coal. The kinetic data could be described by a modified unipore model. The adsorption rates were found to exhibit dependence on pressure and temperature at low pressures, while the calculated diffusivities exhibited little temperature dependence. In addition, the kinetic characteristics were compared between CH_4 and CO_2 adsorption on the block coal. The excess adsorption ratios of CO_2 to CH_4 obtained from the DR+k model decreased with the increasing pressure. 展开更多
关键词 adsorption isotherm thermodynamic model adsorption rate DIFFUSION
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Subjective poor sleep quality in Chinese patients with Parkinson's disease without dementia 被引量:2
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作者 Li Zhang Jingde Dong +1 位作者 weiguo liu Yingdong Zhang 《The Journal of Biomedical Research》 CAS 2013年第4期291-295,共5页
Parkinson's disease (PD) is a common progressive neurological disorder and is composed of motor and nonmotor symptoms. Sleep disturbances are frequent problems for patients with PD. The relationship between sleep d... Parkinson's disease (PD) is a common progressive neurological disorder and is composed of motor and nonmotor symptoms. Sleep disturbances are frequent problems for patients with PD. The relationship between sleep disturbances with Hoehn and Yahr (H&Y) staging have been demonstrated. However, the relationship between sleep disorders and H&Y is still unclear in patients with PD without dementia in Chinese PD patients. In this study, we interviewed 487 non-demented PD patients of Chinese Han descents by H&Y classification. We found that night sleep quality was significantly associated with the severity of PD (P=0.008). Panic disorder severity scale (PDSS) total scores were correlated with PD non-motor symptoms scale (PDNMS) scores (r=-0.528, P〈0.001), the Hamilton depression scale (HAMD) scores (r=-0.545, P〈0.001) and the Hamilton anxiety scale (HAMA) scores (r=-0.498, P〈0.001). Our results indicated that sleep quality deteriorated with the advancing of PD in Chinese non-demented patients with PD. Depression and anxiety may partly explain sleep disturbances in nondemented patients with PD. 展开更多
关键词 sleep quality DEPRESSION ANXIETY Parkinson disease non-demented
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Responses of soil CH_(4) fluxes to nitrogen addition in two tropical montane rainforests in southern China 被引量:1
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作者 Fangtao Wu Changhui Peng +8 位作者 Chuanyao Wang Huai Chen weiguo liu Zhihao liu Hui Wang Hong Li Dexiang Chen Yide Li Shirong liu 《Forest Ecosystems》 SCIE CSCD 2022年第3期335-343,共9页
Background:Atmospheric nitrogen(N)deposition is projected to increase in the next few decades,which may have a marked impact on soil-atmosphere CH_(4) fluxes.However,the impacts of increased atmospheric N depositions ... Background:Atmospheric nitrogen(N)deposition is projected to increase in the next few decades,which may have a marked impact on soil-atmosphere CH_(4) fluxes.However,the impacts of increased atmospheric N depositions on soil CH_(4) flux in tropical rainforests are still poorly understood.From January 2015 to December 2018,a field experiment was conducted in a primary tropical montane rainforest(PTMR)and a secondary tropical montane rainforest(STMR)in southern China to quantify the impact of N additions at four levels(N0:0 kg N⋅ha^(-1)⋅year^(-1);N25:25 kg N⋅ha^(-1)⋅year^(-1);N50:50 kg N⋅ha^(-1)⋅year^(-1);N100:100 kg N⋅ha^(-1)⋅year^(-1)on soil CH_(4) flux.Results:Four years of measurements showed clear seasonal variations in CH_(4) flux in all treatment plots for both forest types(PTMR and STMR),with lower rates of soil CH_(4) uptake during the wet season and higher rates of soil CH_(4) uptake during the dry season.Soil CH_(4) uptake rates were significantly and negatively correlated with both soil temperature and soil moisture for both forest types.Annual CH_(4) uptake for the N0 plots from the PTMR and STMR soils were2.20 and1.98 kg N⋅ha^(-1)⋅year^(-1),respectively.At the PTMR site,mean CH_(4) uptake compared with the N0 treatment was reduced by 19%,29%,and 36%for the N25,N50,and N100 treatments,respectively.At the STMR site,mean CH_(4) uptake compared with the N0 treatment was reduced by 15%,18%,and 38%for the N25,N50,and N100 treatments,respectively.High level N addition had a stronger inhibitory impact on soil CH_(4) uptake than did the low level N addition.Conclusion:Our data suggest that soil CH_(4) uptake in tropical rainforests is sensitive to N deposition.If atmospheric N deposition continues to increase in the future,the soil CH_(4) sink strength of tropical rainforests may weaken further. 展开更多
关键词 Atmospheric nitrogen deposition Greenhouse gases Soil CH_(4)flux Tropical rainforest
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青藏高原中部伦坡拉盆地新生代地层年代、古环境与古高度研究综述
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作者 孙继敏 李建国 +1 位作者 刘卫国 靳春胜 《科学通报》 EI CAS CSCD 北大核心 2024年第18期2463-2479,共17页
新生代以来,地球上最为显著的地貌变化就是印度与亚洲板块碰撞导致的青藏高原隆升.长期以来,关于碰撞的起始时间、碰撞方式与过程以及古高度等均有较大的争议.本文主要针对近年在古高度重建方面最受关注的高原中部伦坡拉盆地的研究进行... 新生代以来,地球上最为显著的地貌变化就是印度与亚洲板块碰撞导致的青藏高原隆升.长期以来,关于碰撞的起始时间、碰撞方式与过程以及古高度等均有较大的争议.本文主要针对近年在古高度重建方面最受关注的高原中部伦坡拉盆地的研究进行了综述,旨在总结年代学、古环境演变以及古高度重建方面的进展和分歧.首先,伦坡拉盆地的新生代地层年代近年获得了长足的进展,特别是在伦坡拉盆地的牛堡组和丁青组地层陆续发现了10层左右的凝灰岩,为限定地层时代提供了很好的绝对年龄约束,牛堡组的时代已经从此前的古新世-始新世调整为始新世-早渐新世,丁青组则为晚渐新世至晚中新世.其次,伦坡拉盆地牛堡组的植物化石揭示了早始新世晚期(47 Ma)为热带亚热带湿润的森林环境,始新世晚期(39 Ma)则为亚热带开阔森林环境.丁青组的植被类型以暖温带针阔叶混交林为主.丁青组中、下部地层记录了40万年准周期的干湿旋回,表明地球轨道的长周期偏心率波动驱动了该时期伦坡拉盆地的古降水变化;而丁青组上部的稳定同位素记录揭示了14 Ma以来高原中部发生的降温与干旱增强事件,而且该事件是对14 Ma以来东南极冰盖扩张、全球持续变冷事件的响应.此外,伦坡拉盆地牛堡组中段及丁青组含有丰富的动植物化石.近年,越来越多的生物学证据(包括植物大化石与孢粉)表明,伦坡拉盆地在晚始新世的古高度基本在2000~2700 m左右,晚渐新世-早中新世初期(26~20 Ma)的古高度为3000~3200 m.即便到晚中新世早期的12 Ma,水生浮叶植物的证据表明,伦坡拉盆地古湖面的最大高度为3400 m,由此表明伦坡拉盆地的海拔高度很可能在晚中新世以后仍有1200 m左右的上升. 展开更多
关键词 青藏高原隆升 伦坡拉盆地 牛堡组与丁青组时代 古环境 古高度
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Effects of neurotrophin-3 on the differentiation of neural stem cells into neurons and oligodendrocytes
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作者 Guowei Zhu Chongran Sun weiguo liu 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第19期1483-1487,共5页
In this study, cells from the cerebral cortex of fetal rats at pregnant 16 days were harvested and cultured with 20 μg/L neurotrophin-3. After 7 days of culture, immunocytochemical staining showed that, 22.4% of cell... In this study, cells from the cerebral cortex of fetal rats at pregnant 16 days were harvested and cultured with 20 μg/L neurotrophin-3. After 7 days of culture, immunocytochemical staining showed that, 22.4% of cells were positive for nestin, 10.5% were positive for 18-111 tubulin (neuronal marker), and 60.6% were positive for glial fibrillary acidic protein, but no cells were positive for 04 (oligodendrocytic marker). At 14 days, there were 5.6% nestin-, 9.6% 13-111 tubulin-, 81.1% glial fibrillary acidic protein-, and 2.2% O4-positive cells. In cells not treated with neurotrophin-3, some were nestin-positive, while the majority showed positive staining for glial fibdllary acidic protein. Our experimental findings indicate that neurotrophin-3 is a crucial factor for inducing neural stem cells differentiation into neurons and oligodendrocytes. 展开更多
关键词 NEUROTROPHIN-3 neural stem cells DIFFERENTIATION NEURON OLIGODENDROCYTES stem cells neuralregeneration
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四海龙湾沉积物多指标反映人类活动从1850年开始显著增强
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作者 江鸿 韩永明 +4 位作者 刘卫国 曹蕴宁 胡婧 樊会敏 刘博 《地球科学进展》 CAS CSCD 北大核心 2024年第1期82-95,共14页
基于全球地质记录的比对,国际人类世工作组建议20世纪中期(约1950年)为人类世的起始时间,四海龙湾沉积物曾被列为“人类世界线层型剖面”的候选地质体之一。但在1950年以前,人类已较深刻地影响了四海龙湾周围地区的环境。通过重建四海... 基于全球地质记录的比对,国际人类世工作组建议20世纪中期(约1950年)为人类世的起始时间,四海龙湾沉积物曾被列为“人类世界线层型剖面”的候选地质体之一。但在1950年以前,人类已较深刻地影响了四海龙湾周围地区的环境。通过重建四海龙湾沉积物900年以来的总有机碳、总有机碳和总氮的摩尔比(C/N)、稳定有机碳同位素(δ^(13)C_(org))和Ca/Ti,以及硅酸盐矿物主要元素Si、Al和K含量的历史序列,平均分辨率约为10年,以气候变化为背景,来探究该地区人类活动的历史。发现人类活动从1850年开始显著增强,在此之前的中世纪暖期和小冰期指标变化大体符合自然规律。1850—1950年指标的变化反映出快速增长的人口破坏了植被,导致风化加剧,地表环境的演变脱离了自然轨道,表明人类活动开始成为一种重要的地质营力,但这段时期的变化只是局地信号;1950年后,C/N持续减小及δ^(13)C_(org)持续负移,反映出在新的社会制度和先进生产力的条件下,四海龙湾周围地区的环境状态再次发生改变,这与全球地质环境的加速变化同步,可以支持国际人类世工作组所提出的“20世纪中期是人类世的起始时间”。 展开更多
关键词 人类世 四海龙湾 地表风化 毁林垦荒 东北地区 人口增长
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PIF4 interacts with ABI4 to serve as a transcriptional activator complex to promote seed dormancy by enhancing ABA biosynthesis and signaling 被引量:1
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作者 Xiaofeng Luo Yujia Dai +15 位作者 Baoshan Xian Jiahui Xu Ranran Zhang Muhammad Saad Rehmani Chuan Zheng Xiaoting Zhao Kaitao Mao Xiaotong Ren Shaowei Wei Lei Wang Juan He Weiming Tan Junbo Du weiguo liu Shu Yuan Kai Shu 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2024年第5期909-927,共19页
Transcriptional regulation plays a key role in the control of seed dormancy,and many transcription factors(TFs)have been documented.However,the mechanisms underlying the interactions between different TFs within a tra... Transcriptional regulation plays a key role in the control of seed dormancy,and many transcription factors(TFs)have been documented.However,the mechanisms underlying the interactions between different TFs within a transcriptional complex regulating seed dormancy remain largely unknown.Here,we showed that TF PHYTOCHROME-INTERACTING FACTOR4(PIF4)physically interacted with the abscisic acid(ABA)signaling responsive TF ABSCISIC ACID INSENSITIVE4(ABI4)to act as a transcriptional complex to promote ABA biosynthesis and signaling,finally deepening primary seed dormancy.Both pif4 and abi4 single mutants exhibited a decreased primary seed dormancy phenotype,with a synergistic effect in the pif4/abi4 double mutant.PIF4 binds to ABI4 to form a heterodimer,and ABI4 stabilizes PIF4 at the protein level,whereas PIF4 does not affect the protein stabilization of ABI4.Subsequently,both TFs independently and synergistically promoted the expression of ABI4 and NCED6,a key gene for ABA anabolism.The genetic evidence is also consistent with the phenotypic,physiological and biochemical analysis results.Altogether,this study revealed a transcriptional regulatory cascade in which the PIF4–ABI4 transcriptional activator complex synergistically enhanced seed dormancy by facilitating ABA biosynthesis and signaling. 展开更多
关键词 ABA ABI4 PIF4 seed dormancy and germination transcriptional complex
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公元600~800年的气候变化促使了吐蕃帝国的兴衰 被引量:5
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作者 侯居峙 冀克家 +8 位作者 朱二雷 董广辉 仝涛 储国强 刘卫国 吴文祥 张水龙 Jade D'Alpoim Guedes 陈发虎 《Science Bulletin》 SCIE EI CAS CSCD 2023年第11期1187-1194,M0004,共9页
公元7~9世纪,吐蕃帝国成为一个介于唐王朝和阿拔斯王国之间的超级区域势力,在中世纪早期的亚洲地缘政治中发挥着重要作用.然而,作为青藏高原历史上唯一一个统一的地方政权,强大的吐蕃帝国兴起和衰落的原因存在诸多争议.本研究利用了青... 公元7~9世纪,吐蕃帝国成为一个介于唐王朝和阿拔斯王国之间的超级区域势力,在中世纪早期的亚洲地缘政治中发挥着重要作用.然而,作为青藏高原历史上唯一一个统一的地方政权,强大的吐蕃帝国兴起和衰落的原因存在诸多争议.本研究利用了青藏高原中部湖泊江错的纹层沉积物,基于精确的纹层定年和多种地球化学指标,重建了亚年际尺度的降水和年代际尺度的温度记录,发现吐蕃帝国发展、鼎盛阶段与一个长达两个世纪的异常温暖湿润期时间一致.生态位模型模拟显示气候的暖湿化可使得青稞可耕种面积扩大,增加农业生产力,并且牧草产量增高,可能会引起高原地区人口增加,并且会有充足的后勤补给.9世纪初的干旱则可能导致农业生产力下降,人口减少,加之内部战乱导致吐蕃迅疾衰亡.降水记录和吐蕃历史事件发生时间的紧密关系意味着吐蕃帝国实施了灵活的对外战略来应对气候变化的影响.在当今全球变暖的背景下,这一研究结果对包括青藏高原在内的高寒地区的农业生产具有重要意义. 展开更多
关键词 农业生产力 耕种面积 温度记录 鼎盛阶段 人口减少 生态位模型 模拟显示 后勤补给
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DeepFilter: A Deep Learning Based Variant Filter for VarDict
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作者 Hao Zhang Zekun Yin +2 位作者 Yanjie Wei Bertil Schmidt weiguo liu 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2023年第4期665-672,共8页
With the development of sequencing technologies,somatic mutation analysis has become an important component in cancer research and treatment.VarDict is a commonly used somatic variant caller for this task.Although the... With the development of sequencing technologies,somatic mutation analysis has become an important component in cancer research and treatment.VarDict is a commonly used somatic variant caller for this task.Although the heuristic-based VarDict algorithm exhibits high sensitivity and versatility,it may detect higher amounts of false positive variants than callers,limiting its clinical practicality.To address this problem,we propose DeepFilter,a deep-learning based filter for VarDict,which can filter out the false positive variants detected by VarDict effectively.Our approach trains two models for insertion-deletion mutations(InDels)and single nucleotide variants(SNVs),respectively.Experiments show that DeepFilter can filter at least 98.5%of false positive variants and retain 93.5%of true positive variants for InDels and SNVs in the commonly used tumor-normal paired mode.Source code and pre-trained models are available at https://github.com/LeiHaoa/DeepFilter. 展开更多
关键词 variant filter deep learning somatic variant
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地球倾角驱动的末次冰期期间南亚地区变暖 被引量:6
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作者 赵成 Eelco J.Rohling +16 位作者 Zhengyu liu 杨小强 张恩楼 程军 Zhonghui liu 安芷生 羊向东 冯小平 孙晓双 张灿 闫天龙 隆浩 晏宏 Zicheng Yuk 刘卫国 于世永 沈吉 《Science Bulletin》 SCIE EI CSCD 2021年第11期1136-1145,M0004,共11页
当前对晚第四纪以来轨道尺度上地球气候变化的认识,主要包括高纬驱动的以~10万年周期为主的冰期-间冰期循环和夏季风影响的以~2.3万年周期为主的低纬水文变化.但是,由于低纬陆地没有较为可靠的温度记录,使得对低纬陆地的长期气候变化仍... 当前对晚第四纪以来轨道尺度上地球气候变化的认识,主要包括高纬驱动的以~10万年周期为主的冰期-间冰期循环和夏季风影响的以~2.3万年周期为主的低纬水文变化.但是,由于低纬陆地没有较为可靠的温度记录,使得对低纬陆地的长期气候变化仍然缺乏全面的理解.本文通过获取云南腾冲青海的一根湖泊沉积岩芯,分析了沉积物中的支链甘油二烷基甘油四醚酯(brGDGTs)和叶蜡氢同位素,分别重建了~9万年以来南亚地区的年平均温度和季风降水的变化序列.结果表明,夏季风降水与之前的研究一致,表现出明显的2.3万年周期,但是年均温度记录揭示了8.8~7.1万年和4.5~2.2万年存在两个暖期,温度变幅2~3℃,与该记录中的冰期-间冰期变幅接近.通过对比TraCE21ka瞬态模拟结果和相关气候驱动因子,发现这两个暖期很可能受当地的年均太阳轨道辐射影响;而低纬地区的年均太阳辐射由以~4.1万年周期为主的地球倾角变化控制,并与高纬地区的年均太阳轨道辐射呈反向关系.此外,该记录中的两个暖期与古人类活动的年代有较强的相关性,表明末次冰期内温度变化可能对亚洲地区古人类的生存有重要的影响. 展开更多
关键词 温度记录 古人类活动 末次冰期 云南腾冲 太阳轨道 辐射影响 暖期 氢同位素
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Carbon isotope and environmental changes in lakes in arid Northwest China 被引量:3
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作者 weiguo liu Xiangzhong LI +4 位作者 Zheng WANG Huangye WANG Hu liu Bo ZHANG Huan ZHANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2019年第8期1193-1206,共14页
The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the recon... The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the reconstruction of terrestrial ecosystems and global climate changes. It has also been widely used in paleolimnological studies in arid northwestern China. In recent years, however, an increasing number of studies have enriched the environmental significance reflected by the stable carbon isotope geochemistry of lakes;therefore, the interpretation of lake δ13 C variations in paleoenvironmental reconstructions should be carefully evaluated from various aspects. In this paper, previous studies from the past several decades on the lacustrineδ13 C variations in arid northwestern China were reviewed, and the possible mechanisms of the δ13 C variations were discussed.Our study will provide a reference for the application of carbon isotope geochemistry in paleoenvironmental reconstructions. 展开更多
关键词 CARBON isotope Lake ARID region of NORTHWESTERN China Total ORGANIC CARBON ORGANIC biomarkers
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Bio-Organic Geochemistry research in China: Advances,opportunities and challenges 被引量:2
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作者 Chuanlun ZHANG Ping'an PENG +3 位作者 Meixun ZHAO Shucheng XIE Jianfang CHEN weiguo liu 《Science China Earth Sciences》 SCIE EI CAS CSCD 2018年第12期1775-1780,共6页
The discipline of "Bio-Organic Geochemistry" is a cross research field between biogeochemistry and traditional organic geochemistry, which focuses on geochemical processes related to the biosynthesis of orga... The discipline of "Bio-Organic Geochemistry" is a cross research field between biogeochemistry and traditional organic geochemistry, which focuses on geochemical processes related to the biosynthesis of organic molecules(particularly lipids) by(micro) organisms, organic matter production by primary producers, degradation of organic matter by microbial processes recorded by retainable lipid biomarkers, and organic proxies for studies of paleo-climate, paleo-environments, paleoecology and Earth evolution. This field aims to go beyond the traditional petroleum-oriented Organic Geochemistry by integrating with biogeochemical concepts concerned mostly with biomolecules from cellular material such as DNA and lipids. A formal Chinese organization in Bio-Organic Geochemistry was established in 2012 when the first conference was held in Guangzhou. This organization has witnessed rapid growth over the past six years with focused research addressing organic proxies in paleoclimate and paleoenvironmental applications, with particular rapid development in glycerol dialkyl glycerol tetraethers-derived proxies. Most progresses in China so far are made following or paralleling the international trend in biogeochemical studies. Things have begun to change with China's ambitious initiatives in several bio-geo programs such as the Ocean Deep Drilling Program of China, the Microbial Hydrosphere Program, the Deep Carbon Observatory, and the Microbiome Program. Looking forward in the 21 st Century, the growing Chinese research community in Bio-Organic Geochemistry faces grand opportunities and challenges as Chinese scientists propel themselves toward global research frontiers. 展开更多
关键词 Bio-Organic Geochemistry BIOGEOCHEMISTRY GEOMICROBIOLOGY PALEOCLIMATE PROXIES Carbon cycles Microbial GENOMICS
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Compound-specific δD and its hydrological and environmental implication in the lakes on the Tibetan Plateau 被引量:2
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作者 Hu liu Hong YANG +1 位作者 Yunning CAO weiguo liu 《Science China Earth Sciences》 SCIE EI CAS CSCD 2018年第6期765-777,共13页
The hydrogen isotopic composition(δD) of n-alkanes in lacustrine sediments is widely used in palaeoenvironmental studies, but the heterogeneous origins and relative contributions of these lipids provide challenges fo... The hydrogen isotopic composition(δD) of n-alkanes in lacustrine sediments is widely used in palaeoenvironmental studies, but the heterogeneous origins and relative contributions of these lipids provide challenges for the interpretation of the increasing dataset as an environment and climatic proxy. We systematically investigated n-alkane δD values from 51 submerged plants(39 Potamogeton, 1 Myriophyllum, and 11 Ruppia), 13 algae(5 Chara, 3 Cladophora, and 5 Spirogyra) and 20 terrestrial plants(10 grasses and 10 shrubs) in and around 15 lakes on the Tibetan Plateau. Our results demonstrate that δD values of C_(29) nalkane are correlated significantly with the lake water δD values both for algae(R^2=0.85, p<0.01, n=9) and submerged plants(R^2=0.90, p<0.01, n=25), indicating that δD values of these algae and submerged plants reflect the δD variation of lake water. We find that apparent hydrogen isotope fractionation factors between individual n-alkanes and water(εa/w) are not constant among different algae and submerged plants, as well as in a single genus under different liminological conditions, indicating that the biosynthesis or environmental conditions(e.g. salinity) may affect their δD values. The δD values of submerged plant Ruppia in the Xiligou Lake(a closed lake) are significant enriched in D than those of terrestrial grasses around the lake(one-way ANOVA,p<0.01), but the algae Chara in the Keluke Lake(an open lake) display similar δD values with grasses around the lake(one-way ANOVA, p=0.826>0.05), suggesting that the n-alkane δD values of the algae and submerged plants record the signal of D enrichment in lake water relative to precipitation only in closed lakes in arid and semi-arid area. For each algae and submerged plant sample, we find uniformed δD values of different chain length n-alkanes, implying that, in combination with other proxies such as Paq and Average Chain Length, the offset between the δD values of different chain length n-alkanes can help determine the source of sedimentary n-alkanes as well as inferring the hydrological characteristics of an ancient lake basin(open vs closed lake). 展开更多
关键词 水文学 环境 高原 西藏 混合物 植物样品 氢同位素 类脂化合物
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青铜器时代中国西北地区出现异常温暖时期 被引量:2
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作者 蒋庆丰 孟博文 +10 位作者 王政 钱鹏 郑佳楠 姜佳玮 赵成 侯居峙 董广辉 沈吉 刘卫国 柳中晖 陈发虎 《Science Bulletin》 SCIE EI CSCD 2022年第4期427-436,M0004,共11页
全新世约4200年前的气候突变事件被认为对早期人类文明的发展有较大的影响,但对此事件之后的陆地气候状态还缺乏全面的理解.通常认为在整个青铜器时代(约4000~2200年前)以冷凉气候为主,而早期人类文明的演化也是在此假设的气候背景下解... 全新世约4200年前的气候突变事件被认为对早期人类文明的发展有较大的影响,但对此事件之后的陆地气候状态还缺乏全面的理解.通常认为在整个青铜器时代(约4000~2200年前)以冷凉气候为主,而早期人类文明的演化也是在此假设的气候背景下解释的.本文通过分析新疆赛里木湖沉积岩芯里的长链烯酮,并更新了青海湖和克鲁克湖已发表的长链烯酮记录,重建了中国西北地区全新世以来的夏季温度变化.结果表明,在全新世变冷的长趋势下,中国西北地区在早中青铜器时代(约4200~2800年前)出现异常温暖的气候状态.对应于此时期较强的太阳活动及结合其他区域也存在的气候异常,推测青铜器时代可能发生了不寻常的气候重组.本文结果对研究青铜器时代人类文明发展和气候变化之间的关系提供了新视角. 展开更多
关键词 Terrestrial temperature HOLOCENE The Bronze Age Northwest China ALKENONES
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Effects of various substrate materials on structural and optical properties of amorphous silicon nitride thin films deposited by plasma-enhanced chemical vapor deposition 被引量:2
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作者 杭良毅 刘卫国 徐均琪 《Chinese Optics Letters》 SCIE EI CAS CSCD 2020年第8期81-86,共6页
The plasma-enhanced chemical vapor deposition(PECVD)technique is well suited for fabricating optical filters with continuously variable refractive index profiles;however,it is not clear how the optical and structural ... The plasma-enhanced chemical vapor deposition(PECVD)technique is well suited for fabricating optical filters with continuously variable refractive index profiles;however,it is not clear how the optical and structural properties of thin films differ when deposited on different substrates.Herein,silicon nitride films were deposited on silicon,fused silica,and glass substrates by PECVD,using silane and ammonia,to investigate the effects of the substrate used on the optical properties and structures of the films.All of the deposited films were amorphous.Further,the types and amounts of Si-centered tetrahedral Si–SivN4-v bonds formed were based upon the substrates used;Si–N4 bonds with higher elemental nitrogen content were formed on Si substrates,which lead to obtaining higher refractive indices,and the Si–SiN3 bonds were mainly formed on glass and fused silica substrates.The refractive indices of the films formed on the different substrates had a maximum difference of0.05(at 550 nm),the refractive index of SiNx films formed on silicon substrates was 1.83,and the refractive indices of films formed on glass were very close to those formed on fused silica.The deposition rates of these SiNx films are similar,and the extinction coefficients of all the films were lower than 10-4. 展开更多
关键词 thin films plasma-enhanced chemical vapor deposition optical properties structural properties substrate materials
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Nutritional evaluation of whole soybean curd made from different soybean materials based on amino acid profiles 被引量:2
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作者 Meili Li Hongming Dong +5 位作者 Dingtao Wu Hong Chen Wen Qin weiguo liu Wenyu Yang Qing Zhang 《Food Quality and Safety》 SCIE CSCD 2020年第1期41-49,共9页
Objectives:Amino acid profiles of whole soybean curds(WSCs)and conventional soybean curds(CSCs)were comparatively studied to 1.,evaluate their nutritional value and 2.,study the suitable soybean material to fabricate ... Objectives:Amino acid profiles of whole soybean curds(WSCs)and conventional soybean curds(CSCs)were comparatively studied to 1.,evaluate their nutritional value and 2.,study the suitable soybean material to fabricate WSCs.Materials and Methods:Nine types of soybean materials were selected to make WSCs and CSCs.Protein digestibility-corrected amino acid score(PDCAAS)and principal component analysis were selected to perform the comparative analysis of amino acid profiles of the products.Results:Total contents of amino acids in WSCs and CSCs were 41.24-54.87 mg/g and 27.77-36.82 mg/g.Content ranges of essential amino acids were 13.59-19.38 mg/g and 8.46-11.76 mg/g for WSCs and CSCs.The essential amino acid pattern of WSCs was basically close to amino acid pattern spectrum requirements except valine and sulfur amino acids.As a limiting amino acid,methionine represented less than 0.4 for PDCAAS in all soybean curds except WSCs made from relay-cropping Nandou12 and Nandou25.Conclusions:The overall quality of amino acids in WSCs was higher than that in CSCs,indicating that WSCs indeed exhibited higher nutritional value than CSCs from the viewpoint of amino acid profile.WSCs with the high nutritional value could be made using Nandou25 and relay-cropping Nandou12 as materials. 展开更多
关键词 amino acid profile whole soybean curds conventional soybean curds protein digestibility-corrected amino acid score comprehensive score
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