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| 1 | 中国的生育率:到底下降了多少?显示文摘1990年代以来 ,中国的生育水平持续下降 ,已经进入低生育国家的行列。 2 0 0 0年人口普查 ,中国的总和生育率为 1 2 2 ,明显存在漏报。那么中国的生育率到底下降了多少 ?本文利用亲生子女法、生育史重构法和胎次递进比方法分析了 1 990年代生育率的下降过程 ,认为 2 0 0 0年总和生育率最准确的估计应为 1 5 8。通过分解总和生育率的变化 ,认为 1 990年代生育水平的下降 ,2 /5归因于结婚年龄的推迟 。 | Robert D.Retherford Minja Kim Choe Chen Jiajian 李希如 崔红艳 | 2004 | 人口研究2004，28，4： | 31 |
| 2 | Deformed trademark retrieval based on 2D pseudo-hidden markou model 显示文摘 | Chang Minja Chen Shuyuan | 2001 | Pattern Recognition2001，34，6： | 1 |
| 3 | Deformed trademark retrieval based on 2D pseudo-hidden Markov model显示文摘 | Chang Minja Chen Shuyuan | 2001 | Pattern Recognition2001，34，6： | 1 |
| 4 | Dimensionality-driven metal to Mott insulator transition in two-dimensional 1T-TaSe_(2)显示文摘Two-dimensional materials represent a major frontier for research into exotic many-body quantum phenomena.In the extreme two-dimensional limit,electron-electron interaction often dominates over other electronic energy scales,leading to strongly correlated effects such as quantum spin liquid and unconventional superconductivity.The dominance is conventionally attributed to the lack of electron screening in the third dimension.Here,we discover an intriguing metal to Mott insulator transition in 1T-TaSe_(2) that defies conventional wisdom.Specifically,we find that dimensionality crossover,instead of reduced screening,drives the transition in atomically thin 1T-TaSe_(2).A dispersive band crossing the Fermi level is found to be responsible for the bulk metallicity in the material.Reducing the dimensionality,however,effectively quenches the kinetic energy of these initially itinerant electrons,and drives the material into aMott insulating state.The dimensionality-driven metal to Mott insulator transition resolves the long-standing dichotomy between metallic bulk and insulating surface of 1T-TaSe_(2).Our work further reveals a new pathway for modulating two-dimensional materials that enables exploring strongly correlated systems across uncharted parameter space. | Ning Tian Zhe Huang Bo Gyu Jang Shuaifei Guo Ya-Jun Yan Jingjing Gao Yijun Yu Jinwoong Hwang Cenyao Tang Meixiao Wang Xuan Luo Yu Ping Sun Zhongkai Liu Dong-Lai Feng Xianhui Chen Sung-Kwan Mo Minjae Kim Young-Woo Son Dawei Shen Wei Ruan Yuanbo Zhang | 2024 | National Science Review2024，11，3： | 0 |
| 5 | Broadband picometer-scale resolution on-chip spectrometer with reconfigurable photonics显示文摘Miniaturization of optical spectrometers is important to enable spectroscopic analysis to play a role in in situ,or even in vitro and in vivo characterization systems.However,scaled-down spectrometers generally exhibit a strong trade-off between spectral resolution and operating bandwidth,and are often engineered to identify signature spectral peaks only for specific applications.In this paper,we propose and demonstrate a novel global sampling strategy with distributed filters for generating ultra-broadband pseudo-random spectral responses.The geometry of all-pass ring filters is tailored to ensure small self-and cross-correlation for effective information acquisition across the whole spectrum,which dramatically reduces the requirement on sampling channels.We employ the power of reconfigurable photonics in spectrum shaping by embedding the engineered distributed filters.Using a moderate mesh of MZls,we create 256 diverse spectral responses on a single chip and demonstrate a resolution of 20 pm for single spectral lines and 30 pm for dual spectral lines over a broad bandwidth of 115 nm,to the best of our knowledge achieving a new record of bandwidth-to-resolution ratio.Rigorous simulations reveal that this design will readily be able to achieve single-picometer-scale resolution.We further show that the reconfigurable photonics provides an extra degree of programmability,enabling user-defined features on resolution,computation complexity,and relative error.The use of SiN integration platform enables the spectrometer to exhibit excellent thermal stability of±2.0℃,effectively tackling the challenge of temperature variations at picometer-scale resolutions. | Chunhui Yao Minja Chen Ting Yan Liang Ming Qixiang Cheng Richard Penty | 2023 | Light(Science & Applications)2023，12，7： | 0 |
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