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信息通信技术 2010年第3期4卷 18-24页

作者： zhang yumei Sheng Yu China Unicom National Engineering Laboratory of Broadband Service Applications Beijing 100032China China Unicom Research Institute Beijing 100048China

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services(BCMCS) to meet an increasing demand for multimedia data services.Single frequency network(SFN) is recognized as an effective way to improve the spectral efficiency of the BCMCS system.To improve the coverage and the data rate of the BCMCS users,an interference cancellation algorithm based on macro diversity is introduced in this paper.The performance of BCMCS in CDMA2000 EV-DO networks under the condition of SFN is evaluated.The simulation results show a significant improvement in bit error ratio(BER) while quantitatively validating the efficiency of our approach.

关键词：移动通信系统频谱效率网络技术单频网

践行大食物观促进全民营养健康和可持续发展的战略选择

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农业经济问题 2023年第5期 11-21页

作者：樊胜根张玉梅中国农业大学全球食物经济与政策研究院北京100083

本文总结我国食物供需面临的挑战,剖析大食物观的科学内涵,从食物消费、生产和贸易角度研究大食物观发展路径,提出保障全民营养健康和可持续发展的战略思考。本文建议引导居民采取可持续健康膳食模式,同时制定相关政策降低营养食物价格... 详细信息

本文总结我国食物供需面临的挑战,剖析大食物观的科学内涵,从食物消费、生产和贸易角度研究大食物观发展路径,提出保障全民营养健康和可持续发展的战略思考。本文建议引导居民采取可持续健康膳食模式,同时制定相关政策降低营养食物价格和增加收入等保障低收入人群的健康膳食;以居民多样化食物需求和大资源观为导向,构建多元化食物供给体系,通过优化食物供给结构、挖掘多种资源、发展设施农业、研发未来食物、转型绿色低碳生产方式和完善全球食物供应链等路径,增强食物供给的可持续性。最后提出前置食物消费政策、扩大农业政策支持范围、优化支持方向、强化科技支撑、创新大协同管理机制和推进高水平开放等践行大食物观的战略选择。

关键词：大食物观食物供需营养健康可持续发展战略选择

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辅食添加时间对婴儿生长发育影响的队列研究

卫生研究 2023年第1期52卷 90-94页

作者：李玭赵艾张健蓝航莲张玉梅北京大学公共卫生学院营养与食品卫生学系北京100191 清华大学万科公共卫生与健康学院北京100084 内蒙古乳业技术研究院有限责任公司呼和浩特010110

目的分析婴儿辅食添加时间分布及其对婴儿6~8月龄生长发育的影响。方法2017年12月至2018年12月选取北京、郴州两地共168对母乳喂养的健康母婴,从婴儿出生随访至8月龄;按照首次辅食添加时间将调查对象分为合理添加辅食组与不合理添加辅食... 详细信息

目的分析婴儿辅食添加时间分布及其对婴儿6~8月龄生长发育的影响。方法2017年12月至2018年12月选取北京、郴州两地共168对母乳喂养的健康母婴,从婴儿出生随访至8月龄;按照首次辅食添加时间将调查对象分为合理添加辅食组与不合理添加辅食组,利用重复度量分析比较随访结束时两组婴儿各项生长发育Z评分的差异。结果在4~6月龄之间合理添加辅食的婴儿占80.4%(n=135);过早添加辅食(小于4月龄)的婴儿占6.5%(n=11);过晚添加辅食(晚于8月龄)的占6.0%(n=10)。重复度量分析结果表明,辅食添加时间不合理的婴儿6~8月龄的年龄别体质量指数Z评分(body mass index for age Z score,BAZ)与辅食添加合理的婴儿差异有统计学意义(P=0.046);首次辅食添加时间不合理的婴儿6月龄的BAZ较高(β=0.615,95%CI 0.053~1.178)。结论北京、郴州两地母乳喂养婴儿过早或过晚添加辅食的婴儿较少,绝大多数婴儿的首次添加辅食时间为4~6月龄;辅食添加时间不合理可能对婴儿的BAZ产生短期影响。

关键词：辅食添加婴儿生长发育队列研究

Analysis of Channel-aware Multichannel ALOHA in OFDMA Wireless Networks

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信息通信技术 2009年第2期3卷 56-61页

作者： zhang yumei Sheng Yu China Unicom Group Broadband Service Applications Co. Ltd For National Engineering Labs Beijing 100032 China China United Telecommunications Corporation Beijing Branch Beijing 100038 China

Orthogonal frequency division multiple access (OFDMA) systems provide multiple channels that can be accessed via random access schemes. In this paper a channel-aware multichannel random access, based on local channel state information (CSI), was investigated and a multichannel slotted ALOHA scheme was proposed accordingly. Also an analytical investigation of total system throughput and the queue state evolution of generic node in the network were present by assuming the channel has been modeled by means of a two state Markov chain. Through the theoretical model and simulation results, we confi rm that the proposed algorithm has the advantage of high throughput and low access delay.

关键词：无线通信网络正交频率多分址移动通信随机配置通话波段

High-rate CH_(4)-to-C_(2)H_(6) photoconversion enabled by Au/ZnO porous nanosheets under oxygen-free system

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Science China Chemistry 2024年第3期67卷 869-875页

作者： Kai Zheng Xiaojing zhang Jun Hu Chengbin Xu Juncheng Zhu Jing Li Mingyu Wu Shan Zhu Li Li Shumin Wang yumei Lv Xin He Ming Zuo Chengyuan Liu Yang Pan Junfa Zhu Yongfu Sun Yi Xie Hefei National Laboratory for Physical Sciences at Microscale National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China State Grid Anhui Electric Power Research Institute Hefei 230601China

Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.

关键词： dual surface-active sites selective methane coupling ethane room temperature

大食物观下农业产业链韧性面临挑战及提升对策

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中州学刊 2023年第4期 54-61页

作者：张玉梅龙文进中国农业大学经济管理学院北京100083

近几十年来,我国农业生产、消费和贸易都发生了显著变化,农业产业链延长,生产率显著提高,农产品供应更加丰富。但是,农业产业链仍面临农业研发能力不强、资源环境承载压力大、灾害风险高、农产品加工产值低和农产品进口高度集中等诸多... 详细信息

近几十年来,我国农业生产、消费和贸易都发生了显著变化,农业产业链延长,生产率显著提高,农产品供应更加丰富。但是,农业产业链仍面临农业研发能力不强、资源环境承载压力大、灾害风险高、农产品加工产值低和农产品进口高度集中等诸多风险挑战,农业产业链韧性不足。为保障新时期粮食安全和加强农业强国建设,亟须提升农业产业链韧性。未来,应借鉴国际上注重农业生产多样化、农业风险管理和农业科技创新等方面的经验,以“大食物观”发展理念,进一步提高农业科技竞争力,加强农业风险管控,拓宽食物来源和丰富供给品类,延伸农业产业链和增强价值链,优化国内生产和国外进口布局,倡导健康的膳食消费模式,从而全面提升农业产业链韧性。

关键词：韧性农业产业链农业食物系统大食物观

Scheduling Algorithm with Quality of Service Support in IEEE 802.16 Networks

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信息通信技术 2009年第4期3卷 44-49页

作者： zhang yumei Sheng Yu China Unicom Group Broadband Service Applications Co. Ltd for National Engineering Labs Beijing 100032 China United Network Telecommunications Corporation Beijing Branch Beijing 100038 China

The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.

关键词：多媒体通信运算法则 MAC

Clinical Study on Simultaneous Modulated Accelerated Radiotherapy and Concurrent Chemotherapy for Locally Advanced Nasopharyngeal Carcinoma

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Clinical oncology and cancer resexreh 2009年第5期6卷 354-358页

作者： Haiqun Lin Baosheng Li Zicheng zhang yumei Wei Limin Zhai Department of Radiotherapy Shandong Cancer Hospital Jinan 250117 Shandong Province. China.

OBJECTIVE To evaluate the clinical efficacy and toxicities ofsimultaneous modulated accelerated radiotherapy (SMART) andconcurrent chemotherapy for locally advanced nasopharyngealcarcinoma.METHODS Eightyseven patients with nasopharyngealcarcinoma received SMART from April 2002 to September2006.According to the UICC staging system,30 patients werediagnosed as stage Ⅱb,42 patients stage Ⅲ,13 patients stage Ⅳaand 2 patients stage Ⅳb.The intensitymodulated radiotherapywas delivered with the'step and shoot' SMART technique withthe prescribed dose of 66-76 Gy (2.2-2.4 Gy/day) to the grosstumor volume (GTV) and positive neck lymph nodes (GTVLN),with 60 Gy (2.0 Gy/day) to the highrisk clinical target volume(CTV1),encompassing the area around the nasopharynx andthe upper neck,and with 54 Gy (1.8 Gy/day) to the lowriskclinical target volume (CTV2),including the lower neck andsupraclavicular area.Among all the patients,31 received 2 cyclesof SMART concurrently with 5 fluorouracil (5-Fu) and cisplatin(the FP group) and 56 received 2 cycles of concurrent cisplatin.All the patients received 3 to 4 cycles of adjuvant combinationchemotherapy of cisplatin and 5fluorouracil starting from the 1stmonth after completion of SMART.RESULTS With a median follow up of 59 months (rangingfrom 19 to 85 months),the 1,2 and 3year overall survival rateswere 100%,94.6% and 91.3% respectively.Acute mucositis andpharyngitis were more frequently observed in the FP group thanin the cisplatin group.CONCLUSION SMART technique provides an excellentopportunity to spare normal tissue and is probably morebiologically effective.Combination of single cisplatin was moretolerable.

关键词：鼻咽癌同步化疗调和加速放疗晚期临床

A New Phase Transition in Dense Vortices

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Chinese Physics Letters 1995年第5期12卷 293-296页

作者： CHEN Zhijian zhang yumei XU Bowei Department of Physics Shanghai Jiaotong UniversityShanghai 200030 Department of Physics Tongji UniversityShanghai 200092

An improved XY model is adopted for the vortices in the superconductors.In the case of high density,the fugacity should be modified by the higher harmonics.By use of the variational effective potential,we analyze the ... 详细信息

关键词： temperature Transition harmonics