期刊文献+
共找到357篇文章
< 1 2 18 >
每页显示 20 50 100
基于四种常用机器学习的梭梭(Haloxylon ammod-endron(C.A.Mey)Bunge)适宜生境分布研究
1
作者 朱妮 郭彦龙 《生态科学》 CSCD 2023年第4期190-199,共10页
梭梭Haloxylon ammodendron (C.A.Mey) Bunge是适应中亚荒漠生境的耐寒、抗旱、耐盐碱C4植物,预测该物种地理分布范围以及未来不同气候变化情景下该物种适宜生境分布的变化,对于我国荒漠区生态环境保护具有重要意义。利用收集的梭梭分... 梭梭Haloxylon ammodendron (C.A.Mey) Bunge是适应中亚荒漠生境的耐寒、抗旱、耐盐碱C4植物,预测该物种地理分布范围以及未来不同气候变化情景下该物种适宜生境分布的变化,对于我国荒漠区生态环境保护具有重要意义。利用收集的梭梭分布数据与33个环境因子,基于四种常用的机器学习算法组成的组合模型对该物种适宜生境在我国西北干旱区的分布进行了预测。结果表明:(1)不同的模型算法的结果在空间上具有较高的一致性,但其分布细节具有一定的差异性。(2)梭梭在我国的适宜生境面积约为0.91×10^(6) km^(2),主要分布在新疆的准噶尔盆地和塔里木盆地边缘,甘肃河西走廊地区,内蒙古巴丹吉林、乌兰布和、腾格里沙漠和库布齐沙漠的西部,青海省柴达木盆地等地区。(3)未来气候变化对该物种适宜生境分布的影响取决于升温幅度,但是在大部分的增温情景中,该物种的适宜生境变化较小。(4)高适宜生境面积为0.19×10^(6) km^(2),应该作为梭梭原生产地保护以及人工种植的重点区域。(5)集成多模型结果的组合物种分布模型能够在一定程度上减少模型的不确定性,增加模型的精度。在环境条件限制性较高的干旱区,加入土壤因素能够有效提高物种分布模型的建模科学性和合理性。 展开更多
关键词 梭梭(Haloxylon ammodendron(C.A.mey)Bunge 物种分布 机器学习 组合模型 荒漠物种
下载PDF
MEY与MSY的经济学比较分析 被引量:1
2
作者 林光纪 《福建水产》 2004年第1期38-42,75,共6页
本文针对西方经济学教科书中提出渔业资源开放系统MEY小于MSY时 ,才能达到经济福利最大化的论点 ,用静态分析、时间价值分析指出了其中的错误所在 ,并以蛛网模型的混沌现象说明渔业资源开放系统中 ,混沌导致渔业厂商的共同活动并非收敛... 本文针对西方经济学教科书中提出渔业资源开放系统MEY小于MSY时 ,才能达到经济福利最大化的论点 ,用静态分析、时间价值分析指出了其中的错误所在 ,并以蛛网模型的混沌现象说明渔业资源开放系统中 ,混沌导致渔业厂商的共同活动并非收敛于理想的MEY或MSY。 展开更多
关键词 最大经济产量 最大可持续产量 mey MSY 经济学 比较分析 渔业资源 静态分析 蛛网混沌 时间价值 渔业资源开放系统
下载PDF
Ginsenoside-Rg_6, a Novel Triterpenoid Saponin from the Stem-Leaves of Panax ginseng C. A. Mey. 被引量:12
3
作者 Xiu Wei YANG, Long Yun LI, Jian Ming TIAN, Zhi Wei ZHANG, Jin Mei YE, Wei Fang Gu (National Research Laboratory of Natural & Biomimetic Drugs, Peking University, Beijing 100083) (Academy of Chinese Traditional Medicine and Materia Medica of Jilin Provinc 《Chinese Chemical Letters》 SCIE CAS CSCD 2000年第10期909-912,共4页
A novel dammarane-type triterpene oligoglycoside, named ginsenoside-Rg6 3, was isolated from the stem-leaves of Panax ginseng C. A. Mey., together with two known ones, 20(S)-ginsenoside-Rg2 1 and 20(R)-ginsenoside-Rg2... A novel dammarane-type triterpene oligoglycoside, named ginsenoside-Rg6 3, was isolated from the stem-leaves of Panax ginseng C. A. Mey., together with two known ones, 20(S)-ginsenoside-Rg2 1 and 20(R)-ginsenoside-Rg2 2. On the basis of chemical and physicochemical evidence , the structure of ginsenoside-Rg6 have been elucidated as 6-O-(-L-rhamnosyl-(1?2)-(-D-glucopyranosyl-dammarane-(E)-20(22), 24-diene-3(, 6(, 12(-triol. 展开更多
关键词 Panax ginseng C. A. mey. stem-leaves TRITERPENOID ginsenoside-Rg_6.
下载PDF
A new coumarin from Wikstroemia indica (L.) C.A.Mey 被引量:1
4
作者 Yang Chen Wen Wei Fu +3 位作者 Li Xin Sun Qia Wang Wei Qi Hua Yu 《Chinese Chemical Letters》 SCIE CAS CSCD 2009年第5期592-594,共3页
A new coumarin was obtained from the stems and roots of Wikstroemia indica (L.) C. A. Mey. Its structure was elucidated as methyl 3-(2-hydroxy-4-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yloxy) phenyl) propanoate ... A new coumarin was obtained from the stems and roots of Wikstroemia indica (L.) C. A. Mey. Its structure was elucidated as methyl 3-(2-hydroxy-4-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yloxy) phenyl) propanoate by spectroscopic methods. 展开更多
关键词 Wikstroemia indica (L.) C.A. mey COUMARIN Structure elucidation
下载PDF
Study on Surface Sterilization Method for Tissue Culture of Haloxylon ammodendron(C.A.Mey.) Bunge Seeds 被引量:1
5
作者 Dong WANG Guiping ZHAO 《Agricultural Biotechnology》 CAS 2012年第3期26-28,共3页
[ Objective ] The aim was to select appropriate sterilization methods and explants for tissue culture of Haloxylon ammodendron ( C. A. Mey. ). [Method] H. ammodendron (C. A. Mey. ) seeds were used as experimental ... [ Objective ] The aim was to select appropriate sterilization methods and explants for tissue culture of Haloxylon ammodendron ( C. A. Mey. ). [Method] H. ammodendron (C. A. Mey. ) seeds were used as experimental materials to investigate the sterilization results of different sterilization treatments and the effect of different seed sizes on the survival rate of aseptic seedlings. [ Result] Sterilization of H. ammodendron ( C.A. Mey. ) seeds achieved the best result by using 75% alcohol for 15 min and 0.1% mercuric chloride for 8 min. Seeds with diameter φ 〉 2.0 mm were used as explants and achieved relatively high surviv- al rate of aseptic seedlings, which reached above 65%. [ Conclusion] This study established a surface sterilization method for tissue culture of H. ammodendron ( C. A. Mey. ) Bunge seeds. 展开更多
关键词 Haloxylon ammodendron (C. A. mey. Bunge Sterilization methods Tissue culture
下载PDF
Determination of Saponins in Leaf of Panax Ginseng C. A. Mey. by High Performance Liquid Chromatography
6
作者 LIU Gui-ying ZHOU Hong-yu +6 位作者 LU Juan ZHU Na GUI Ming-yu JIN Yong-ri ZHANG Yi-hua WANG Xin LI Xu-wen 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第3期297-301,共5页
A high performance liquid chromatography(HPLC) with UV detection was established for simultaneous determination of saponins in the leaf of Panax ginseng C. A. Mey. Nine ginsenosides(Rbl, Rb2, Rb3, Rc, Rd, F1, F2, F... A high performance liquid chromatography(HPLC) with UV detection was established for simultaneous determination of saponins in the leaf of Panax ginseng C. A. Mey. Nine ginsenosides(Rbl, Rb2, Rb3, Rc, Rd, F1, F2, F3, F5) and notoginsenoside Fe(NFe) were studied. Among the saponins, the ginsenosides F1, F2, F3, F5 and NFe were determined by HPLC-UV method for the first time. The determination of the ginsenosides via the HPLC-UV method was performed on a reversed-phase C18 column with gradient elution in 40 min. The linearity, precision, accuracy, and detection limit for determining the saponins were studied and the samples from different areas in China were analyzed. The HPLC-ESI-MS was used to identify the saponins. The results indicate that the HPLC-UV provided a good accuracy, reproducibility and sensitivity for the determination of the ten saponins. 展开更多
关键词 Panax ginseng C. A. mey. SAPONINS HPLC Quantification DETERMINATION
下载PDF
MEY型多功能立铣刀
7
《模具工程》 2004年第3期26-26,共1页
关键词 mey 立铣刀 日本京瓷公司 结构 性能
下载PDF
Metabolomics analysis reveals the renal protective effect of Panax ginseng C. A. Mey in type 1 diabetic rats 被引量:2
8
作者 WANG Xin-Sen HU Ming-Xin +2 位作者 GUAN Qing-Xiang MEN Li-Hui LIU Zhong-Ying 《Chinese Journal of Natural Medicines》 SCIE CAS CSCD 2022年第5期378-386,共9页
The dry root and rhizome of Panax ginseng C. A. Mey has garnered much interest owing to its medicinal properties against diabetes and cardiovascular diseases. In this study, an ultra-high performance liquid chromatogr... The dry root and rhizome of Panax ginseng C. A. Mey has garnered much interest owing to its medicinal properties against diabetes and cardiovascular diseases. In this study, an ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS)-based metabolomics approach was used to illustrate the therapeutic mechanisms of ginseng extract on the serum and urinary metabolic profiles in streptozotocin-induced type 1 diabetes mellitus (T1DM) rats. Pharmacological and renal parameters in response to the administration of ginseng were also evaluated. In total, 16 serum endogenous metabolites and 14 urine endogenous metabolites, including pyruvic acid, indoleacetic acid, and phenylacetylglycine, were identified as potential biomarkers for diabetes. Pathway enrichment and network analysis revealed that the biomarkers modulated by ginseng were primarily involved in phenylalanine and pyruvate metabolism, as well as in arginine biosynthesis. Moreover, the levels of several renal injury-related biomarkers in T1DM rats were significantly restored following treatment with ginseng. The administration of the extract helped maintain tissue structure integrity and ameliorated renal injury. The findings suggest that the regulatory effect of ginseng extract on T1DM involves metabolic management of diabetic rats, which subsequently attenuates T1DM-induced early renal dysfunction. 展开更多
关键词 Panax ginseng C.A.mey Type 1 diabetes Metabolomics
原文传递
Clonal diversity of Clintonia udensis Trautv.et Mey. populations and its correlation with ecological factors 被引量:1
9
作者 WANG YiLing 1,2 ,LI Xin 1 ,GUO Jing 1 ,GUO ZhiGang 1 &ZHAO GuiFang 1 1Key Laboratory of Resource Biology and Biotechnology in Western China(Ministry of Education),College of Life Sciences, Northwest University,Xi’an 710069,China 2College of Life Sciences,Shanxi Normal University,Linfen 041004,China 《Science China(Life Sciences)》 SCIE CAS 2008年第7期575-576,578-582,共7页
The clonal diversity of Clintonia udensis Trautv.et Mey.was detected by ISSR markers among 16 populations,and its correlation with ecological factors was analyzed as well in this work.Results showed that individuals(c... The clonal diversity of Clintonia udensis Trautv.et Mey.was detected by ISSR markers among 16 populations,and its correlation with ecological factors was analyzed as well in this work.Results showed that individuals(clonal ramets)per genotype were 1.12 and 1.149 at population and species levels,respectively,and that the 16 populations were all multiclonal.The detected genotypes were localized,without exception,within populations but demonstrated relatively high clonal differentiation among populations.The clonal diversity of the studied populations was high,with the average Simpson's index of 0.975,while the genets showed a clonal architecture of"guerilla".The population genetic diversities revealed by genet were consistent with those by ramet,further confirming their genetic differentiation among populations.And its genotype diversity within populations probably resulted largely from the frequent seedling regeneration and self-compatibility.In addition,the correlation analysis further revealed that,among the ecological factors,Simpson's index of C.udensis had a significant positive correlation(P<0.05)with pH values in the soil but not others. 展开更多
关键词 Clintonia udensis Trautv.et mey. POPULATION CLONAL DIVERSITY ECOLOGICAL factors CORRELATION
原文传递
Improving innovation and entrepreneurship education in higher institutions: the impact of "Mass Entrepreneurship and Innovation" education on undergraduates' entrepreneurial intentions 被引量:1
10
作者 ShaoYing Lu Sun Ye +1 位作者 XiaoShu Xu Yuwei Zhao 《教育技术与创新》 2024年第1期10-26,共17页
The exploration of the way"mass entrepreneurship and innovation"(MEI)education influences students'aspirations to become entrepreneurs has grown into an important area of analysis in studies related to h... The exploration of the way"mass entrepreneurship and innovation"(MEI)education influences students'aspirations to become entrepreneurs has grown into an important area of analysis in studies related to higher education.This research intends to examine the consequences of MEI education on students'tendency towards entrepreneurship,and to put forward methods for augmenting the teaching of innovation and entrepreneurship in private higher educational establishments.To achieve this objective,questionnaires and semi-structured interviews were employed in the study,which involved a total of 197 students and five education experts.The statistical analysis of the questionnaire data revealed that MEI education was positively related to students'entrepreneurial intentions,and that both entrepreneurial experience and family entrepreneurial background played moderating roles in this relationship.The interview findings indicated that private universities could enhance educational reforms by designing talent training programs,developing diversified curricula,and developing more professional entrepreneurial platforms to encourage students'entrepreneurial intentions.This study offers fresh insights for improving and perfecting the mechanism of innovation and entrepreneurship education in private universities. 展开更多
关键词 Private universities Mass Entrepreneurship and Innovation MEI education entrepreneurial intention
下载PDF
关帝山青扦径向生长对厄尔尼诺-南方涛动(ENSO)事件的响应
11
作者 黄晓霞 王李乐 +1 位作者 莫旭昱 江源 《生态与农村环境学报》 CAS CSCD 北大核心 2024年第7期919-926,共8页
关帝山位于华北气候过渡区,受到厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)事件的强烈影响。分析关帝山青扦(Picea wilsonii)径向生长与ENSO事件的响应关系,有助于了解气候变化对位于气候过渡区的山地森林树木生长的影响。... 关帝山位于华北气候过渡区,受到厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)事件的强烈影响。分析关帝山青扦(Picea wilsonii)径向生长与ENSO事件的响应关系,有助于了解气候变化对位于气候过渡区的山地森林树木生长的影响。利用关帝山海拔2000~2200 m的青扦树轮样芯,构建了树轮宽度差值年表,通过Pearson相关分析确定树轮宽度指数与月均温、月降水量、多元ENSO指数(multivariate ENSO index,MEI)的相关关系,使用交叉小波变换分析(cross-wavelet transform analysis,XWT)得到青扦树轮宽度差值年表与MEI的共同功率谱周期,比较青扦宽轮和窄轮对ENSO事件响应的差异,并运用时序叠加分析(superimposed epoch analysis,SEA)探究典型ENSO事件后青扦径向生长的变化。结果表明:(1)关帝山青扦径向生长主要受到前一年生长季前期(p3-p5)和当年生长季(c7,c9)高温的限制,前两年生长季开始时期(pp5)和结束时期(pp9)的降水则有利于青扦生长;(2)青扦树轮宽度差值年表与前一年5月到当年3月(p5-c3)的MEI指数呈显著负相关(P<0.05),两者有2~5.5年的共同功率谱周期;(3)关帝山青扦的宽轮主要受拉尼娜事件影响,窄轮主要受厄尔尼诺事件影响。厄尔尼诺事件发生的当年及后3年,青扦径向生长速度显著减慢(P<0.01)。 展开更多
关键词 多元ENSO指数(MEI) 宽轮与窄轮 交叉小波变换分析 气候过渡区 青扦
下载PDF
The Translation of Slangs in Two English Versions of Jin Ping Mei
12
作者 ZHANG Yihong 《Cultural and Religious Studies》 2024年第3期146-157,共12页
The Chinese classical novel Jin Ping Mei abounds with a large number of slangs,which correspondingly leads to the difficulty of the novel’s English translation and also gives rise to the emergence of diversified Engl... The Chinese classical novel Jin Ping Mei abounds with a large number of slangs,which correspondingly leads to the difficulty of the novel’s English translation and also gives rise to the emergence of diversified English versions.The two English translators,Clement Egerton and David Roy,adopted completely different translation strategies when dealing with Chinese slangs in the novel.Their different translation purposes account for the significant disparity concerning the slang translation.Clement Egerton pays more attention to the novel’s plot in his English version The Golden Lotus,rather than the unique expressions of the original language,so that in the concrete translation process,a domestication strategy is adopted for the sake of the target language readers’understanding,resulting in distortion and omission of the slang expressions in the translated text.By contrast,the translation purpose which guides David Roy’translation The Plum in the Golden Vase is to convey the complexity and literariness of the original Chinese text,and hence the foreignization strategy is employed concerning slang translation,which aims to accurately reproduce the unique expressions of slangs in the original text.Comparatively speaking,David Roy’s translation succeeds in preserving the Chinese slangs to the greatest extent both in form and meaning,and can shed light for the slang translation in other Chinese literary works. 展开更多
关键词 Jin Ping Mei SLANGS domestication and foreignization translation purpose
下载PDF
STUDIES ON EMBRYOLOGY OF GINSENG(Panax ginseng C. A. Mey.)
13
作者 李方元 马淑琴 +4 位作者 杜令阁 杨振棠 李安生 邵启全 傅志明 《Chinese Science Bulletin》 SCIE EI CAS 1989年第22期1933-1934,共2页
The macrosporogenesis and microsporogenesis, the formation of female and male gametophyte, the process of double fertilization, the development of embryo andendosperm, and the formation of seeds of ginseng (Panax gins... The macrosporogenesis and microsporogenesis, the formation of female and male gametophyte, the process of double fertilization, the development of embryo andendosperm, and the formation of seeds of ginseng (Panax ginseng C. A. Mey.) 展开更多
关键词 fertilization EMBRYO sperm mey OVARY continually ANTHER INFERIOR young nuclei
原文传递
分数阶广义Birkhoff系统的Mei对称性及其守恒量
14
作者 王璐 张毅 《云南大学学报(自然科学版)》 CAS CSCD 北大核心 2023年第4期846-854,共9页
研究分数阶广义Birkhoff系统的对称性和守恒律.首先,根据分数阶广义Pfaff-Birkhoff原理,建立分数阶广义Birkhoff系统的运动微分方程;其次,基于动力学函数在经历群的无限小变换后仍然满足原方程的不变性,给出分数阶广义Birkhoff系统的Me... 研究分数阶广义Birkhoff系统的对称性和守恒律.首先,根据分数阶广义Pfaff-Birkhoff原理,建立分数阶广义Birkhoff系统的运动微分方程;其次,基于动力学函数在经历群的无限小变换后仍然满足原方程的不变性,给出分数阶广义Birkhoff系统的Mei对称性的定义和判据方程;再次,建立并证明该系统的Mei对称性定理,给出分数阶Mei守恒量.整数阶广义Birkhoff系统、分数阶Birkhoff系统和分数阶Hamilton系统Mei对称性定理是其特例,最后举例以说明定理的应用. 展开更多
关键词 分数阶微积分 广义BIRKHOFF系统 MEI对称性 MEI守恒量
下载PDF
基于分数阶模型的非完整系统的Mei对称性及其守恒量
15
作者 王璐 张毅 《力学季刊》 CAS CSCD 北大核心 2023年第3期633-642,共10页
为了进一步揭示非完整系统的对称性和守恒量之间的内在关系,提出并研究基于分数阶模型的非完整系统的Mei对称性及其守恒量.首先,根据分数阶d’Alembert-Lagrange原理建立基于分数阶模型的非完整系统的动力学方程.其次,根据动力学方程中... 为了进一步揭示非完整系统的对称性和守恒量之间的内在关系,提出并研究基于分数阶模型的非完整系统的Mei对称性及其守恒量.首先,根据分数阶d’Alembert-Lagrange原理建立基于分数阶模型的非完整系统的动力学方程.其次,根据动力学方程中的动力学函数经无限小变换后仍满足原方程的不变性,建立分数阶模型下非完整系统的Mei对称性定理,给出Mei守恒量.再次,讨论了几个特例:分数阶Hamilton系统、经典非完整系统和受非完整约束的分数阶Lagrange系统的Mei对称性定理.文末举例说明结果的应用. 展开更多
关键词 非完整系统 MEI对称性 MEI守恒量 分数阶模型
下载PDF
时间尺度上Hamilton系统的两类Mei对称性及其Mei守恒量
16
作者 孔楠 朱建青 《商丘师范学院学报》 CAS 2023年第6期4-8,共5页
研究时间尺度上Hamilton系统的两类Mei对称性及由Mei对称性导致的守恒量.给出Hamilton系统的第一类Mei对称性定义和判据方程,引入时间尺度上的谐调函数,得出系统Mei对称性直接导致的广义Mei守恒量的条件和形式,同时,给出该系统在时间尺... 研究时间尺度上Hamilton系统的两类Mei对称性及由Mei对称性导致的守恒量.给出Hamilton系统的第一类Mei对称性定义和判据方程,引入时间尺度上的谐调函数,得出系统Mei对称性直接导致的广义Mei守恒量的条件和形式,同时,给出该系统在时间尺度上的第二类Mei对称性的定义及判据,进而推出其直接导致的Mei守恒量.并分别举例说明结果. 展开更多
关键词 时间尺度 HAMILTON系统 MEI对称性 MEI守恒量
下载PDF
时间尺度上Nielsen方程的Mei对称性导致的两类新型守恒量
17
作者 孔楠 朱建青 《河南教育学院学报(自然科学版)》 2023年第1期31-35,共5页
研究时间尺度上单自由度非迁移完整力学系统Nielsen方程的Mei对称性,及由Mei对称性导致的两类新型Mei守恒量。给出系统的Mei对称性定义和判据方程,得到系统Mei对称性导致的两类新型Mei守恒量的条件和形式,并举例说明结果。
关键词 时间尺度 NIELSEN方程 MEI对称性 结构方程 新型Mei守恒量
下载PDF
天山南北坡树轮稳定碳同位素对气候的响应差异 被引量:7
18
作者 秦莉 尚华明 +2 位作者 张同文 刘卫平 张瑞波 《生态学报》 CAS CSCD 北大核心 2021年第14期5713-5724,共12页
利用采自天山南坡阿克苏河流域、天山北坡伊犁河流域和吉尔吉斯斯坦伊塞克湖流域的树木年轮样本,按照树轮稳定碳同位素研究步骤,分别建立了天山南坡和天山北坡各2条树轮稳定碳同位素去趋势序列(δ13 Ccorr)。采用相关函数和共线性分析... 利用采自天山南坡阿克苏河流域、天山北坡伊犁河流域和吉尔吉斯斯坦伊塞克湖流域的树木年轮样本,按照树轮稳定碳同位素研究步骤,分别建立了天山南坡和天山北坡各2条树轮稳定碳同位素去趋势序列(δ13 Ccorr)。采用相关函数和共线性分析揭示了天山南北坡树轮稳定碳同位素与各气候要素之间的关系。结果表明,天山南坡树轮稳定碳同位素与生长季降水、相对湿度显著负相关,而与温度没有明显的相关关系,表明影响天山南坡树轮稳定碳同位素分馏的主要气候因子是生长季水分状况,尤其是降水;天山北坡树轮稳定碳同位素与生长季尤其是夏季的平均气温、平均最高气温和饱和水汽压亏缺显著正相关,而与降水量、相对湿度显著负相关,表明影响天山北坡树轮稳定碳同位素分馏的气候因子可能较为复杂。进一步分析表明,夏季温度、降水和相对湿度共同调控着天山北坡雪岭云杉树轮稳定碳同位素分馏。 展开更多
关键词 天山 雪岭云杉(Picea schrenkiana Fisch.et mey) 树木年轮 稳定碳同位素 气候响应
下载PDF
全球变化背景下天山西部雪岭云杉径向生长和水分利用效率对气候要素的响应 被引量:8
19
作者 秦莉 尚华明 +6 位作者 喻树龙 张合理 姜盛夏 张同文 刘可祥 苟晓霞 张瑞波 《沙漠与绿洲气象》 2021年第3期1-9,共9页
全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13... 全球气候变暖和大气CO_(2)浓度(Ca)急剧上升已成为不争的事实,并对森林生态系统有着深远的影响,全面理解森林生态系统对全球变化的响应至关重要。中亚干旱区特有树种雪岭云杉(Picea schrenkiana Fisch. et Mey)树轮稳定碳同位素(δ^(13)C)和水分利用效率(iWUE)对气候变暖和大气CO2浓度急剧上升的响应缺乏研究。本研究利用天山西部伊犁河流域的雪岭云杉树轮样本,使用树木年代学方法和树轮稳定碳同位素技术,建立树轮宽度年表、稳定碳同位素(δ^(13)C)以及内禀水分利用效率(iWUE)序列,分析了树轮δ13C和iWUE的长期变化特征,探讨了树轮δ13C和iWUE对气候的响应规律以及iWUE与树轮宽度的关系。结果表明,主要的气候因子并没有强烈地限制树木径向生长;夏季平均气温对树轮δ^(13)C分馏有重要影响,iWUE的长期变化受到全球Ca增加和升温趋势影响,但直接影响iWUE年际变化的主要因素是饱和水汽压亏缺(VPD)。全球升温和Ca增加导致了iWUE的持续升高,但并没有导致雪岭云杉树木径向生长的明显增加。 展开更多
关键词 树木年轮 稳定碳同位素(δ^(13)C) 水分利用效率 雪岭云杉(Picea schrenkiana Fisch.et mey) 天山 气候变化
下载PDF
不同贮藏条件对梭梭种子萌发活力的影响 被引量:6
20
作者 王泽 任财 +4 位作者 梁燕 颜安 麻浩 罗艳丽 粟玲 《湖北农业科学》 2020年第8期121-125,共5页
以吐鲁番梭梭[Haloxylon ammodendron(C.A.Mey.)Bunge]树体上的成熟种子为材料,研究贮藏时间、贮藏温度和贮藏种子含水量对梭梭种子萌发活力的影响。结果表明,室温和冰箱贮藏种子9个月,种子发芽率随着贮藏时间的延长呈下降趋势,下降幅度... 以吐鲁番梭梭[Haloxylon ammodendron(C.A.Mey.)Bunge]树体上的成熟种子为材料,研究贮藏时间、贮藏温度和贮藏种子含水量对梭梭种子萌发活力的影响。结果表明,室温和冰箱贮藏种子9个月,种子发芽率随着贮藏时间的延长呈下降趋势,下降幅度达46.50和35.50个百分点,各时期冰箱贮藏种子发芽率的下降幅度低于常温贮藏。不同温度下贮藏梭梭种子3个月的发芽率、发芽势、发芽指数和胚鲜重特征为-10℃>-18℃>-4℃>4℃>常温,且随着贮藏温度的降低呈先升高后降低,差异显著。不同梭梭种子含水量贮藏3个月的发芽率、发芽指数、胚根长和活力指数随着种子含水量的降低呈先升高后降低趋势,种子含水量为5.50%的降低幅度最小。贮藏温度与活力指数间呈极显著负相关,贮藏种子含水量与发芽指数和活力指数间呈极显著负相关,种子发芽率、活力指数与不同贮藏条件间的相关性高低顺序均为贮藏种子含水量>贮藏温度>贮藏时间,而发芽势、发芽指数与不同贮藏条件间的相关性高低顺序均为贮藏温度>贮藏种子含水量>贮藏时间。 展开更多
关键词 贮藏条件 梭梭[Haloxylon ammodendron(C.A.mey.)Bunge]种子 萌发 活力
下载PDF
上一页 1 2 18 下一页 到第
使用帮助 返回顶部