检索结果-南通市图书馆

Seasonal and Annual Variations of CO_2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2013年第1期12卷 147-158页

作者： WANG Wen liao yun-cheng GUO Qiang College of Agronomy Northwest A&F University

To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

关键词： CO 2 flux carbon sequestration soil water content rainfall event rain-fed winter wheat agro-ecosystem

Effect of polyamine on seed germination of wheat under drought stress is related to changes in hormones and carbohydrates

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第12期15卷 2759-2774页

作者： LIU Yang XU Hong WEN Xiao-xia liao yun-cheng College of Agronomy Northwest A&F University

Drought is a multifaceted stress condition that inhibits crop growth. Seed germination is one of the critical and sensitive stages of plants, and its process is inhibited or even entirely prevented by drought. Polyamines （PAs） are closely associ- ated with plant resistance to drought stress and seed germination. However, little is known about the effect of PA on the seed germination of wheat under drought stress. This study investigated the involvement of PAs in regulating wheat seed germination under drought stress. Six wheat genotypes differing in drought resistance were used, and endogenous PA levels were measured during seed germination under different water treatments. In addition, external PAwas used for seed soaking and the variation of hormones, total soluble sugar and starch were measured during the seed germination under different water treatments. These results indicated that the free spermidine （Spd） accumulation in seeds during the seed germination period favored wheat seed germination under drought stress; however, the free putrescine （Put） accumulation in seeds during the seed germination period may work against wheat seed germination under drought stress. In addition, seed soaking in Spd and spermine （Spm） significantly relieved the inhibition of seed germination by drought stress; howev- er, soaking seeds in Put had no significant effect on seed germination under drought. External Spd and Spm significantly increased the endogenous indole-3-acetic acid （IAA）, zeatin （Z）＋zeatin riboside （ZR）, abscisic acid （ABA）, and gibberellins （GA） contents in seeds and accelerated the seed starch degradation and increased the concentration of soluble sugars in seeds during seed germination. This may promote wheat seed germination under drought stress. In conclusion, free Spd and Put are key factors for regulating wheat seed germination under drought stress and the effects of Spd and Put on seed germination under drought notably related to hormones and starch metab

关键词： polyamine drought seed germination wheat abscisic acid starch

Asymmetric and Single-Side Splitting of Dissipative Solitons in Complex Ginzburg–Landau Equations with an Asymmetric Wedge-Shaped Potential

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2019年第1期36卷 24-27页

作者： yun-Cheng liao Bin Liu Juan Liu Jia Chen National Engineering Laboratory for Destructive Testing and Optoelectronic Sensing Technology and Application Nanchang HangKong University Nanchang Institute of Science and Technology

We report some novel dynamical phenomena of dissipative solitons supported by introducing an asymmetric wedge-shaped potential(just as a sharp ‘razor') into the complex Ginzburg–Landau equation with the cubicquintic nonlinearity. The potentials corresponding to a local refractive index modulation with breaking symmetry can be realized in an active optical medium with respective expanding antiwaveguiding structures. Using the razor potential acting on a central dissipative soliton, possible outcomes of asymmetric and single-side splitting of dissipative solitons are achieved with setting different strengths and steepness of the potentials. The results can potentially be used to design a multi-route splitter for light beams.

关键词： Dissipative Solitons Complex Ginzburg-Landau Equations Asymmetric Wedge-Shaped Potential

Clinical Features and Microvascular Complications Risk Factors of Early-onset Type 2 Diabetes Mellitus

在线全文

学校读者我要写书评

暂无评论

Current Medical Science 2019年第5期39卷 754-758页

作者： Jia-xin HUANG yun-fei liao Yu-ming LI Department of Ultrasound Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China Department of Endocrinology Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China

The aim of this research was to study the clinical features and microvascular complications risk factors of early-onset type 2 diabetes mellitus(T2DM).We analyzed the clinical data from 1421 T2DM inpatients at Wuhan Union *** were divided into early-onset T2DM group(diagnostic age40 years).All subjects underwent a standardized assessment of microvascular *** were compared with independent-samples t test or Chi-square *** logistic regression was used to determine the risk factors of microvascular *** with early-onset T2DM were more inclined to have a lower systolic blood pressure(SBP),a longer duration of diabetes and higher levels of body mass index(BM1),uric acid(UA),fasting plasma glucose(FPG),total cholesterol(TC),triglyceride(TG)and glycosylated hemoglobin(HbAlc)than those with lateonset T2DM(P<0.05).The prevalence of diabetic retinopathy(DR)was significantly higher and that of diabetic peripheral neuropathy(DPN)was significantly lower in early-onset group than in late-onset group(P<0.05).For DN,UA was an independent risk factor in early-onset *** and TG were independent risk factors in late-onset *** DR,duration of diabetes and SBP were independent risk factors in early-onset *** of diabetes,SBP and HbAlc were independent risk factors in late-onset *** study demonstrated that the clinical characteristics of early-onset T2DM were metabolic disorders,including glucose metabolism,lipid metabolism and amino acid ***-onset T2DM was more likely to be associated with *** potential pathogenesis of early and late-onset T2DM might be *** management of metabolic risk factors especially HbA1c,SBP,TG and UA is advised to be performed in the early stage of diabetes.

关键词： early-onset type 2 diabetes mellitus diabetic microvascular complication diabetic nephropathy diabetic retinopathy diabetic peripheral neuropathy

Photonic zitterbewegung and its interpretation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第2期21卷 76-80页

作者： Wang Zhi-Yong Xiong Cai-Dong Qiu Qi liao-yun School of Optoelectronic Information University of Electronic Science and Technology of ChinaChengdu 610054China

In terms of the volume-integrated Poynting vector, we present a quantum field-theory investigation of the zitterbewegung （ZB） of photons, and show that this ZB occurs only in the presence of virtual longitudinal and scalar photons. To present a heuristic explanation for such a ZB, by assuming that the space time is sufficiently close to the flat Minkowski space, we show that the gravitational interaction can result in the ZB of photons.

关键词： zitterbewegung photons gravitational field

Phase Morphology, Crystallization Behavior and Mechanical Properties of Poly(L-lactide) Toughened with Biodegradable Polyurethane: Effect of Composition and Hard Segment Ratio

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2015年第9期33卷 1294-1304页

作者： Qian Xing Rong-bo Li 董侠 Xiu-qin Zhang liao-yun Zhang Du-jin Wang School of Chemistry and Chemical Engineering University of Chinese Academy and Sciences Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Engineering Plastics Institute of Chemistry Chinese Academy of Sciences Petrochina Petrochemical Research Institute

Polyester-based biodegradable polyurethane （PU） with different hard segment ratios was selected to modify the impact toughness of poly（L-lactide）（PLLA）. The influence of blending composition and hard segment ratio of PU on the phase morphology, crystallization behavior and mechanical properties of PLLA/PU blends has been investigated systematically. The results showed that the PU particles were uniformly dispersed in PLLA matrix at a scale from sub- microns to several microns. The glass transition temperature of PU within these blends decreased compared to that of neat PU, but rose slightly with its content and hard segment ratio. The presence of PU retarded the crystallization ability of PLLA, whereas enhanced its elongation at break and impact resistance effectively. As the PU content reaches up to 30 wt%, the phenomenon of brittle-ductile transition occurred, resulting in a rougher fracture surface with the formation of fibril-like structure. Moreover, under the same concentrations, the elongation at break and impact strength of PLLA blends decreased slightly with the increase of hard segment ratio of PU.

关键词： Poly(L-lactide) Polyurethane Phase morphology Impact modification Hard segment ratio.

A case history study on causation of the landslide in Santa Clara,California, USA

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2015年第2期7卷 185-192页

作者： yun liao Sadek M. Derrega Craig A. Hall Kleinfelder 1330 Broadway Suite 1200 Oakland CA 94612 USA Kleinfelder 4670 Willow Road Suite 100 Pleasanton CA 94588 USA

This paper presents a case history study on the geologic investigation and numerical modeling of areactivated landslide in the County of Santa Clara, California to identify the failure mechanism. Thelandslide occurred on an approximately 18.3-m high, north-facing slope during March 2011. The landslidemeasured about 33.5 m in width and about 51.8 m in length. Along the toe of the slope, a residentialstructure with a swimming pool was built on a cut and fill pad and there are several other structurespresent along the western side of the pad. The landslide occurred immediately to the south of theresidential building and moved northward between the County Road A and the house＇s side yard. Themovement of the landslide resulted in damaging the west-bound traffic lane of County Road A andencroached onto the paved driveway for the residential property. An investigation was performed toidentify the failure mechanism of the landslide to conclude whether Road A re-alignment by the Countyor prominent cutting performed along the lower portion of the slope by the homeowner during 2000through 2004 contributed to the reactivation of the old landslide deposit. The investigation included sitereconnaissance, reviewing available published geologic information, reviewing site-specific geologic andgeotechnical data developed by other consultants, and performing numerical modeling. The outcomes ofthe investigation indicate that the primary causation for the reactivation and failure of the subject preexistinglandslide is the prominent cutting performed along the lower portion of the slope during 2000through 2004 and water tank cut bench. The Road A re-alignment did not contribute to the reactivationof the old landslide deposit. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

关键词： Pre-existing landslide ailure mechanism Slope stability

Investigations on methane hydrate formation,dissociation,and viscosity in gas-water-sand system

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第5期19卷 2420-2430页

作者： Shang-Fei Song Shun-Kang Fu Qing-yun liao Bo-Hui Shi Hong-Ju Chen Jing Gong State Key Laboratory of Natural Gas Hydrates/National Engineering Laboratory for Pipeline Safety China University of PetroleumBeijing102249China PipeChina West East Pipeline Company Shanghai200122China Key Lab of Deepwater Engineering CNOOC Research InstituteBeijing100028China

Understanding the kinetics and viscosity of hydrate slurry in gas-water-sand system is of great significance for the high-efficiency and high-safety development of natural gas *** effect of micronsized sands with various concentrations and particle sizes on the hydrate formation,dissociation,and viscosity in gas-water-sand system are investigated in this *** experimental results show that the hydrate induction time in the sandy system is slightly prolonged compared to the pure gas-water system,and the inhibition effect first strengthens and then weakens as the sand concentration increases from0 wt%to 5 wt%.Besides,the difference of hydrate formation amount in various cases is not *** concentration and particle size of sand have little effect on the kinetics of hydrate *** promoting and inhibiting effects on hydrate formation have been found in the sandy multiphase *** the viscosity characteristics,there are three variations of hydrate slurry viscosity during the formation process:Steep drop type,S-type and Fluctuation ***,appropriate sand size is helpful to reduce the randomness of slurry viscosity ***,even at the same hydrate volume fraction,the slurry viscosity in the formation process is significantly higher than that in dissociation process,which needs further *** work provides further insights of hydrate formation,dissociation,and viscosity in gas-water-sand system,which is of great significance for safe and economic development of natural gas hydrates.

关键词： Hydrate slurry Micron-sized sands Hydrate formation Hydrate dissociation Viscosity characteristics

Effects of Water-Collecting and -Retaining Techniques on Photosynthetic Rates, Yield, and Water Use Efficiency of Millet Grown in a Semiarid Region

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2012年第7期11卷 1119-1128页

作者： WEN Xiao-xia ZHANG De-qi liao yun-cheng JIA Zhi-kuan JI Shu-qin College of Agronomy Northwest A&F University Yangling 712100 P.R.China Wheat Research Centre Henan Academy of Agricultural Sciences Zhengzhou 450002 P.R. China

Field experiments were conducted in 2003 and 2004 to study the effects of plastic ridges and furrow film mulching （plastic film on sowing, as well as plastic film on flat soil and hole sowing） and chemicals （a drought resistant agent and a water- retaining agent） on growth, photosynthetic rate, yield, and water use efficiency （WUE） of spring millet （Setaria italica L.）. The experimental results showed that water-collecting and -retaining techniques can effectively increase soil moisture content, the leaf photosynthetic rate and crop growth. Due to increased soil moisture under the plastic-covered ridge and furrow water-collecting in July and August, dry matter and plant height had a increase at the booting stage （late growth advantage）. However, the plastic-covered flat soil and hole sowing reduced soil evaporation during early growth, the increase of dry matter and plant height appeared at the seedling stage （early growth advantage）. Plastic-covered ridge and furrow sowing supplemented with chemical reagents had significant positive effects on water collection and soil moisture retention. Improvement of soil moisture resulted into the increase of the photosynthetic rate, dry matter accumulation yield and WUE. The water-collecting and -retaining techniques can improve WUE and enhance crop yield. Correlation analysis demonstrated that the photosynthetic rate under the water-collecting and -retaining techniques was significantly associated with the soil moisture, but had no significant relationship with leaf chlorophyll content. Plastic- covered ridge and furrow sowing supplemented with chemical reagents increased the yield and WUE by 114% and 8.16 kg ha-1 mm-1, respectively, compared with the control; while without the chemical reagents the yield and WUE were 95% and 7.42 kg ha-1 mm-1 higher, respectively, than those of the control.

关键词： water use efficiency Loess Plateau of China plastic film mulch drought-resistant agent water-retaining agent