共查询到20条相似文献，搜索用时 15 毫秒
1.
<正>The Earth is a very large and complex system that consists of human and natural components interacting bidirectionally with each other,thus forming coupled human and natural systems (CHANS)[1].The increasing dominance of human impacts,especially after the 1950s [2],marked a new era for the Earth,the Anthropocene,which means humans have become the main drivers of the evolution of changes in the Earth system.Therefore,modeling CHANS is essential for understanding the emergent system prope... 相似文献
2.
Huizhong Fan Mingpan Huang Youhua Chen Wenliang Zhou Yibo Hu Fuwen Wei 《国家科学评论(英文版)》2023,(6):108-116
Marine biodiversity plays important roles in ocean ecosystem services and has substantial economic value.Species diversity,genetic diversity and phylogenetic diversity,which reflect the number,evolutionary potential and evolutionary history of species in ecosystem functioning,are three important dimensions of biodiversity.Marine-protected areas have been demonstrated as an effective area-based tool for protecting marine biodiversity,but only 2.8 % of the ocean has been fully protected.It is urge... 相似文献
3.
GUO Huadong 《中国科学院院刊(英文版)》2009,23(4):226-228
Global change refers in the atmosphere, oceans, to anthropogenic changes biosphere, pedosphere and lithosphere over the past century. It is a long process with large dimensions. Factors sensitive to these changes mainly include performance factors （such as temperature and precipitation）, response factors （such as eco-system, natural disasters, water resources, variations in snow and ice）, and driving factors （greenhouse gases and reflection rates）. Global change has caught the attention of the world. 相似文献
4.
The oceans account for 71% of the Earth’s surface and are rich in the most advantageous and characteristic resources of marine microbes. The research on diversity is the key point for exploring and exploiting marine microbial resources. Giving attention to species diversity and genetic diversity of marine microbes, discovering novel metabolites with multiple functions, revealing key secondary metabolic process and the main regulation mechanisms in marine microbes, and developing a new technology of biosynthesis, are the important foundation for discovering innovative drugs and developing functional products with characteristics. The present paper has reviewed the recent advances in the four research areas of marine microbial species diversity, genetic diversity, chemical diversity and metabolic diversity in China. 相似文献
5.
Diego Bueso Maria Piles Philippe Ciais Jean-Pierre Wigneron álvaro Moreno-Martínez Gustau Camps-Valls 《国家科学评论(英文版)》2023,(5):167-179
Environmental change is a consequence of many interrelated factors.How vegetation responds to natural and human activity still needs to be well establishe d,quantified and understood.Re cent satellite missions providing hydrologic and ecological indicators enable better monitoring of Earth system changes,yet there is no automatic way to address this issue directly from observations.Here,we develop an observation-based methodology to capture evidence of changes in global terrestrial ecosystems an... 相似文献
6.
Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions an... 相似文献
7.
GUO Huadong 《中国科学院院刊(英文版)》2013,(2):96-98
Remote sensing, which came into being at the first International Symposium on Remote Sensing of Environment （ISRSE） 50 years ago, has enabled people to obtain objecive and realistic spatial and temporal information through the application of Earth observation technologies and analyze and understand the macro-level changes of the Earth system from a spaial view. The technology of Earth observaion from space has incomparable advantages in the study of the Earth. This aricle introduces the 50-year development of Earth observaion in the world and the 30-year development of Earth observaion in China and reflects on the building of China＇s Earth observaion system. 相似文献
8.
《中国科学院院刊(英文版)》2008,22(2)
Dr. Yang Weiping has been appointed executive vice director-general of the CAS Beijing Institute of Genomics (BIG). He obtained his B.S. degree in biology from Hebei Normal University in 1985, and his PhD in ecology from the CAS Institute of Zoology (IOZ) in 1996. He went to the US in 1998 for six-month training in biology diversity information system management and in 2000 he became a professor of IOZ. Afterwards he went to UK for an advanced study in project administration and organization management. ... 相似文献
9.
<正>Large-scale complex structures,such as spacecraft cabins,aircraft composite skins and launch vehicle fuel tanks,are the core components of the equipment in aerospace,energy,shipbuilding and other fields.Their milling quality and efficiency are factors directly affecting the performance and productivity of spacecraft,aircraft and other key equipment.This kind of structure generally features large dimension,high accuracy, 相似文献
10.
<正>After eons of evolution,biological systems have developed excellent performance in terms of sensing,intelligence,and actuation—the three primary robotics elements that are closely related to the overall performance of robot systems.For example,the buccal pits of some snakes,as the necessary sensors for accurate predation,have a high-temperature sensitivity of 0.003 K[1]; 相似文献
11.
搜索引擎中相关性反馈技术 总被引：10，自引：1，他引：10
As an important component of search engines, the relevance feedback system is very effective for improving the performance of search engines. This paper firstly reviews the history of relevance feedback technology in the past 30 years, then introduces 2 major methods in relevance feedback, i. e. term reweighting and query expansion, and discusses the relevance feedback technologies based on vector space model and statistical ranking model. 相似文献
12.
结合军队新型装备采办人才队伍的建设问题,利用系统动力学方法对人才队伍的规模、组织机构等因素,进行了仿真分析和绩效评估。建立了绩效评估的指标体系,提出人才队伍进出的泊松分布模型,基于系统动力学模型对规模调整因子等变量进行了仿真分析。Abstract： As for the training of talented persons for the acquisition of new equipment in the army,this paper uses the system dynamics method for simulation analysis and performance evaluation of the size of talented persons,the organizational institutions and so on.The paper constructs the performance evaluation index system,brings forward the Poisson distribution model for the passing in and out of talented persons,and makes a simulation analysis of the variables such as the factor of size regulation based on the system dynamics model. 相似文献
13.
Jianqiu Wang Zhong Zheng Pengqing Bi Zhihao Chen Yafei Wang Xiaoyu Liu Shaoqing Zhang Xiaotao Hao Maojie Zhang Yongfang Li Jianhui Hou 《国家科学评论(英文版)》2023,(6):215-225
Large voltage losses are the main obstacle for achieving high efficiency in organic solar cells(OSCs).Here we construct ternary OSCs by introducing an asymmetric small molecule acceptor AITC into PBDB-TCl:BTP-eC9 system and demonstrate the effectiveness in simultaneously decreasing energy disorder and non-radiative voltage losses.It is found that the introduction of AITC can modify domain size and increase the degree of crystallinity,which enhances open-circuit voltage and power conversion effic... 相似文献
14.
Hai-Ling Wang Donglin Liu Jian-Hua Jia Jun-Liang Liu Ze-Yu Ruan Wei Deng Shiping Yang Si-Guo Wu Ming-Liang Tong 《国家科学评论(英文版)》2023,(4):123-132
High-nuclear lanthanide clusters have shown great potential for the administration of high-dose mononuclear gadolinium chelates in magnetic resonance imaging(MRI). The development of high-nuclear lanthanide clusters with excellent solubility and high stability in water or solution has been challenging and is very important for expanding the performance of MRI. We used N-methylbenzimidazole-2-methanol(HL) and LnCl3·6H2O to synthesize two spherical lanthanide clusters, Ln 相似文献
15.
《中国科学院院刊(英文版)》2002,16(1)
The CAS has published the 2002 Science & Society series. The series, which consists of reports on scientific development, high-tech development and sustainable development, aims to introduce the world's scientific and technological (S&T) progress and developmental trends in 2001, review the changes in the frontiers of science and technology, pinpoint the main problems in research and development (R&D), and recount S&T development in China. Through the series, it is hoped that China's decades-long efforts at capacity building of sustainability will be made clear to the world, including theoretical exploration, contents, identification,dynamic monitoring, parametric system and quantitative analysis. 相似文献
16.
Yue Liu Zhengwei Yang Xinxin Zou Shuchang Ma Dahui Liu Maxim Avdeev Siqi Shi 《国家科学评论(英文版)》2023,(7):234-250
Data-driven machine learning(ML) is widely employed in the analysis of materials structure-activity relationships,performance optimization and materials design due to its superior ability to reveal latent data patterns and make accurate prediction.However,because of the laborious process of materials data acquisition,ML models encounter the issue of the mismatch between a high dimension of feature space and a small sample size(for traditional ML models) or the mismatch between model parameters a... 相似文献
17.
Higher-order exceptional points(HOEPs) with extraordinary responsivity are expected to exhibit a vastly improved performance in detection-related applications.However,over the past few years,such an approach has been questioned due to several potential drawbacks,including the stringent parameter re quirements,fundamental resolution limits and noise.Here,exploring the conse quence of nonlinear gain saturation in exceptional singularities of non-Hermitian systems,we offer a feasible scheme to over... 相似文献
18.
Fang Xin 《中国科学院院刊(英文版)》2003,17(3)
Reform is a process of insti-tutional changes, in which,at any stage, the character-istics of a given institutional arrange-ment must have its contextual logicand cognate inter-relations of mu-tual causality. Just as Douglass C.North points out: History is alwaysimportant and its importance lies notonly in the fact that we might takesomething valuable from the past,but that the present and future areto link the past via the continuity ofa societys institutional system. Thechoice of today and … 相似文献
19.
《中国科学院院刊(英文版)》2005,(3)
Climate change is real There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring1. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in r… 相似文献
20.
Background and significance of the collaborative research
Microbes predominate in the planet biosphere and are the richest in biodiversity. The diversity of their living strategies and the range of t... 相似文献