期刊文献+
共找到16篇文章
< 1 >
每页显示 20 50 100
核桃优质高效栽培技术 被引量:3
1
作者 郗荣庭 《北方果树》 2000年第6期29-32,共4页
关键词 核桃 生长可性 品种 栽培技术
下载PDF
Understanding Relationship Between Accessibility and Economic Growth:A Case Study from China(1990–2010) 被引量:10
2
作者 JIAO Jingjuan WANG Jiaoe +1 位作者 JIN Fengjun DU Chao 《Chinese Geographical Science》 SCIE CSCD 2016年第6期803-816,共14页
China′s economy and transport infrastructure have both experienced rapid development since 1978, and especially since 1990. Today, China is the second-largest economic entity in terms of GDP and has the largest high-... China′s economy and transport infrastructure have both experienced rapid development since 1978, and especially since 1990. Today, China is the second-largest economic entity in terms of GDP and has the largest high-speed rail(HSR) network and the second-largest expressway network in the world. This paper explores the relationship between accessibility and economic growth in China from 1990 to 2010. In the study, the basic research units include 333 prefecture-level cities and four municipalities. We explore a bivariate analysis framework of accessibility and economic growth, and their increase rates, to examine this relationship using long-term panel data. The results indicate that, first, accessibility and economic growth show a significant positive relationship using both cross-section and panel data, while the increase rate in accessibility and GDP indicate no significant relationship using cross-section data and a poor significant relationship using panel data. Second, the distributions of local advantage are uneven. Cities with low local advantage with respect to accessibility and GDP are mainly located in China′s eastern coastal region or the provincial capitals, while those with low local advantage in terms of their increase rates are located in the western region. Third, as China′s economic growth and transport networks have evolved, the distribution of local advantage shows little change in terms of accessibility and GDP, but a greater change in terms of their increase rates, which is largely influenced by the distribution of expressway and HSR networks. 展开更多
关键词 ACCESSIBILITY economic growth China GDP transport infrastructure
下载PDF
Partial Characteristics of Hydrogen Production by Fermentative Hydrogen-producing Bacterial Strain B49 被引量:5
3
作者 王相晶 Ren Nanqi +2 位作者 Xiang Wensheng Lin Ming Guo Wanqian 《High Technology Letters》 EI CAS 2003年第3期65-70,共6页
To investigate the characteristics of hydrogen production by a novel fermentative hydrogen-producing bacterial strain B49 (AF481148 in EMBL), batch experiments are conducted under different conditions. Hydrogen produc... To investigate the characteristics of hydrogen production by a novel fermentative hydrogen-producing bacterial strain B49 (AF481148 in EMBL), batch experiments are conducted under different conditions. Hydrogen production has a correlation with cell growth and the consumption of glucose and soluble protein. The optimum pH for cell growth is 4.5±0.15. At acidic pH 4.0±0.15, the bacteria has the maximum accumulated hydrogen volume of 2382 ml/L culture and the maximum hydrogen evolution rate of 339.9 ml/L culture·h with 1% glucose. The optimum temperature for cell growth and hydrogen production is 35℃. In addition, fermentative hydrogen-producing bacterial strain B49 can generate hydrogen from the decomposition of other organic substrates such as wheat, soybean, corn, and potato. Moreover, it can also produce hydrogen from molasses wastewater and brewage wastewater, and hydrogen yields are 137.9 ml H 2/g COD and 49.9 ml H 2/g COD, respectively. 展开更多
关键词 hydrogen production hydrogen-producing bacterial strain B49 CHARACTERISTICS
下载PDF
ELEVATED SOLUBLE EPIDERMAL GROWTH FACTOR RECEPTOR LEVEL IN PITUITARY ADENOMA AND CARCINOMA 被引量:4
4
作者 Yan-guoKong Zu-yuanRen Chang-baoSu Ren-zhiWang Wen-bingMa WeiLian 《Chinese Medical Sciences Journal》 CAS CSCD 2004年第3期199-202,共4页
To investigate effect of the soluble epidermal growth factor receptor (sEGFR/sErbB1) level in the periph-eral blood in development, invasiveness, apoplexy of each type of pituitary tumor. Methods The sEGFR level was d... To investigate effect of the soluble epidermal growth factor receptor (sEGFR/sErbB1) level in the periph-eral blood in development, invasiveness, apoplexy of each type of pituitary tumor. Methods The sEGFR level was determined in peripheral serum from 190 patients with pituitary diseases by enzyme linked immunosobent assay. The sEGFR levels were measured in 10 pituitary Rathke’s pouch, 18 pituitary hyperplasia, 161 pituitary adenomas including 30 microadenomas, 83 large adenomas, 48 giant adenomas, 1 pituitary carcinoma, and 28 hea-lthy controls. Results In the patients with pituitary hyperplasia, microadenoma, large adenoma, giant adenoma, and pituitary carci-noma, the sEGFR level was 188.92 ± 32.62, 209.83 ± 19.01, 333.20 ± 69.33, 405.85 ± 37.38, and 617.45 fmol/mL indepen-dently. They were all significantly higher than patients with pituitary Rathke’s pouch (156.78 ± 18.24 fmol/mL, P < 0.001) and healthy control group (159.11 ± 40.50 fmol/mL, P < 0.05). The sEGFR level in pituitary carcinoma was higher than pi-tuitary adenoma. In patients with pituitary adenoma, the sEGFR level was positive correlated to the size of pituitary adeno-mas (r = 0.998), the significant difference was observed for the sEGFR level in each group of the patients with pituitary adenomas (P < 0.001). Furthermore, in patients with pituitary ACTH-secreting microadenomas, the serum sEGFR levels in invasiveness (295.00 ± 77.80 fmol/mL) was higher than that in non-invasiveness (210.60 ± 16.4 fmol/mL, P < 0.05). In pati-ents with pituitary ACTH-secreting, PRL-secreting, GH-secreting, and non-functioning large adenomas, the serum sEGFR levels in invasiveness (407.86 ± 28.50, 399.25 ± 30.10, 386.00 ± 13.08, and 369.25 ± 36.70 fmol/mL) was higher than that in non-invasiveness (335.25 ± 63.49, 300.64 ± 47.57, 297.00 ± 61.93, and 269.30 ± 25.68 fmol/mL) respectively (P < 0.05). In patients with invasive pituitary PRL-secreting, GH-secreting, and non-functioning giant adenomas, the serum sEGFR levels not significantly different in between invasiveness (417.50 ± 35.94, 409.50 ± 69.14, and 417.50 ± 44.13 fmol/mL) and non-invasiveness (386.00 ± 49.64, 417.50 ± 44.03, and 409.51 ± 35.17 fmol/mL) (P > 0.05). In patients with pituitary large adeno-mas, the sEGFR levels in pituitary apoplexy (377.48 ± 39.18 fmol/mL) was higher than that in non-pituitary apoplexy (343.18 ± 68.17 fmol/mL, P > 0.05). Conclusions The increased level of peripheral serum sEGFR is concomitant with development, proliferous size of the adenomas in patients with pituitary adenomas. In addition, the elevated levels of serum sEGFR occur in pituitary apoplexy as clinical active tumors, and the non-invasive ACTH secreting adenomas. The sEGFR levels could be differen-tiated helpfully between pituitary adenomas and non-pituitary adenomas. These data suggest that serum sEGFR could be as a referable marker of the size and activation of proliferation in pituitary adenoma. 展开更多
关键词 pituitary adenoma pituitary carcinoma soluble epidermal growth factor receptor
下载PDF
Structural engineering of 3D hierarchical Cd0.8Zn0.2S for selective photocatalytic CO2 reduction 被引量:12
5
作者 Lei Cheng Dainan Zhang +2 位作者 Yulong Liao Jiajie Fan Quanjun Xiang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第1期131-140,共10页
The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is high... The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2. 展开更多
关键词 Cd0.8Zn0.2S flowers Self-assembly growth Photocatalytic CO2 reduction High selectivity Visible-light irradiation
下载PDF
Influence of crystallographic orientation on growth behavior of spherical voids
6
作者 张新明 刘文辉 +1 位作者 唐建国 叶凌英 《Journal of Central South University of Technology》 EI 2008年第2期159-164,共6页
The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dep... The influence of crystallographic orientation on the void growth in FCC crystals was numerically simulated with 3D crystal plasticity finite element by using a 3D unit cell including a spherical void, and the rate-dependent crystal plasticity theory was implemented as a user material subroutine. The results of the simulations show that crystallographic orientation has significant influence on the growth behavior of the void. Different active slip systems of the regions around the void cause the discontinuity in lattice rotation around the void, and the corner-like region is formed. In the case of the void located at grain boundary, large heterogeneous deformation occurs between the two grains, and the equivalent plastic deformation along grain boundary near the void in the case of θ=45^o (θ is the angle between grain boundary direction and X-axis) is larger than the others. Large difference of orientation factor of the two grains leads to large equivalent plastic deformation along grain boundary, and the unit cell is more likely to fail by intergranular fracture. 展开更多
关键词 crystallographic orientation void growth crystal plasticity user subroutine finite element method
下载PDF
Improvement of light uniformity by lighting arrangement for standardized crop production
7
作者 Lee Hwa-Soo Kwon Sook-Youn Lim Jae-Hyun 《Journal of Central South University》 SCIE EI CAS 2014年第11期4311-4319,共9页
In a commercialized, fully artificial plant factory, artificial luminaire is arranged in a unified way using a general illumination theory, an actual measurement, or an empirical methodology. However, with these metho... In a commercialized, fully artificial plant factory, artificial luminaire is arranged in a unified way using a general illumination theory, an actual measurement, or an empirical methodology. However, with these methods, lightings are implemented without considering specific optical characteristics of lighting or material characteristics of each component that constructs a cultivation system, resulting in an amount of light that becomes irregular. The amount of lighting is closely related with the growth and quality of crops, and the deviation between points where cultivated crops are located causes quality difference in the produced crops, thus impairing the economic feasibility of a plant factory. In this regard, a simulation to figure out an optimum lighting layout was performed. Arrangements based on the spectrum distribution of light source and reflector materials were implemented to ascertain the distance between lighting and height of lighting and gather information in the pre-treatment process to improve the uniformity of light in the plant cultivation system. Improvement of around 15% in light uniformity is achieved compared with the existing system after the simulation is carried out. This result would reduce the deviation in crop growth to make uniform quality crop production possible. 展开更多
关键词 high-quality crop light uniformity improvement optimal lighting layout fully artificial plant factory Relux simulation
下载PDF
A software cost model with maintenance and risk costs for safety-critical systems
8
作者 刘宏伟 杨孝宗 +1 位作者 曲峰 董剑 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2006年第5期584-587,共4页
According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets: common faults and fatal faults. Common faults cause slight loss when they are ... According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets: common faults and fatal faults. Common faults cause slight loss when they are activated. A fatal fault can lead to significant loss, and even damage the safety-crltical system entirely when it is activated. A software reliability growth model for safety-critical systems is developed based on G - 0 model. And a software cost model is proposed too. The cost model considers maintenance and risk costs due to software failures. The optimal release policies are discussed to minimize the total software cost. A numerical exampie is provided to illustrate how to use the results we obtained. 展开更多
关键词 safety-critlcal system software reliability growth model software cost model optimal software release time
下载PDF
Utilization of Mill Effluent for Growth, Availability and Uptake of Nutrients by Palm Oil Seedlings
9
作者 Nenny Nurlaeny Mahfud Arifin Denny Sobardini 《Journal of Agricultural Science and Technology(B)》 2017年第5期332-338,共7页
A large amount of palm oil mill effluent is one of the issues faced by palm oil producers in Indonesia. To alleviate the environmental pollution, it is necessary to reduce the problem by using it as a liquid organic f... A large amount of palm oil mill effluent is one of the issues faced by palm oil producers in Indonesia. To alleviate the environmental pollution, it is necessary to reduce the problem by using it as a liquid organic fertilizer. A pot experiment to determine the effects of mill effluent on growth of palm oil seedlings (Elaeis guineensis Jacq.), availability and uptake of macronutrients was conducted in Tandun Plantation Unit, province of Riau, Indonesia. The experiment used a randomized block design, consisting nine combinations of mill effluent doses (3.2, 6.4 and 9.6 L) and recommended fertilizer doses (100%, 75%, 50% NPKMg) in 20 kg soil and one control. The experiment was replicated three times. The results showed that plant height, stem diameter and number of fronds of palm oil seedlings at 26 weeks after planting (WAP) were significantly affected by application of 9.6 L mill effluent with 50%-75% NPKMg, The enhancement of soil organic C (Co,g) content, soil pH and cation exchange capacity due to the application of 9.6 L mill effluent combined with 50% NPKMg caused the availability of soil P and total N (Ntot) increased significantly, while exchangeable K was affected by application of 6.4 L mill effluent combined with 100% NPKMg. All treatments did not affect soil exchangeable Mg. A positive correlation between availability of soil N, P, K and its uptake by palm oil seedlings at 26 WAP were indicated by r = 0.61, 0.63 and 0.57, respectively. 展开更多
关键词 K Mg mill effluent N palm oil (Elaeis guineensis Jacq.) phosphate.
下载PDF
Strategies for enhancing economic growth and ecological sustainability in Xinjiang province, China
10
作者 ZHANG Feng-hua Munir Hanjra YUN Hui 《Journal of Environmental Science and Engineering》 2009年第1期52-61,共10页
In arid regions, fragile ecological environment is an obstacle to economic development; an efficient pattern of eco-economic development could be sought from different strategies in such regions. China's Xinjiang pro... In arid regions, fragile ecological environment is an obstacle to economic development; an efficient pattern of eco-economic development could be sought from different strategies in such regions. China's Xinjiang province is the most typical arid region in the world, in fact, contradiction among ecological issue and economic development is intense. In this paper, the natural resource condition, social and economic developments are analyzed in Xinjiang province, with emphasis on the economic development stages underpinned by resource superiority after the economic reform era. We argue that: Xinjiang's economic development was determined comprehensively by geography, ecological resources, and human activity; however to explore a new development pattern with lower dependence on ecological resources, lower cost, more protection to the environment, higher value added and levels of science and technology and knowledge is a key challenge for future economic development. Based on the comparison between past and present, Green strategies should be exclusively chosen for eco-economic development due to the pressure on ecological resources, and the sustainable developmental green strategies include: ecology stratagem, trade stratagem, structure adjustment stratagem, capital stratagem, human resources stratagem. The key challenge is to provide supportive policy and instructional environment to foster such strategies. 展开更多
关键词 eco-economy sustainable development arid area
下载PDF
Sustainable Urban Restructuring of Khartoum: A Revolutionary Measure for Rapid Growth Absorption and Urban Changes
11
作者 Sharaf Eldin Ibrahim Bannaga 《Journal of Civil Engineering and Architecture》 2013年第6期732-745,共14页
Rapidly developing cities are under continuous physical and social changes which make sustainable urban growth concept a matured line of thinking. They are therefore, in need of restructuring to contain these changes.... Rapidly developing cities are under continuous physical and social changes which make sustainable urban growth concept a matured line of thinking. They are therefore, in need of restructuring to contain these changes. Likewise, Khartoum is growing rapidly and is subjected to continual transformation. It started in Independence Day (1/1/1956) by 〈3% of Sudan population and reached 16.8% in 2010 while its physical block grew beyond imagination. The objective of this paper is to throw light on Khartoum rapid growth change effects which necessitated implementation of a revolutionary restructuring programme. At first, huge rural influxes were absorbed and later physical distortions were corrected. This included squatter settlements' treatment to strengthen urban fabric, reallocation of incompatible urban functions, revitalization of the CBD (central business district) and other urban renewal schemes. Transportation lines were extended to ease people mobility and higher population concentrations were diluted, particularly the filthy slums. Old neighbourhoods, traditional villages, etc. were re-planned and popular physical development was encouraged. The restructuring programme appropriated population distribution, administrative districts, new local markets' locations and urban activities' distribution. The programme attained social benefits, particularly availing shelter and essential social services. Difficulties from relocation processes were encountered but settlements' regularization achieved social justice and sustained urban growth. 展开更多
关键词 Khartoum RESTRUCTURING rapid growth urban changes urban functions SLUMS RELOCATION re-planning.
下载PDF
Hybrid PdAg alloy-Au nanorods: Controlled growth, optical properties and electrochemical catalysis 被引量:10
12
作者 Qiao Zhang Xia Guo +3 位作者 Zhenxing Liang Jianhuang Zeng Jian Yang Shijun Liao 《Nano Research》 SCIE EI CAS CSCD 2013年第8期571-580,共10页
Controllable growth of high-quality hybrid nanostructures is highly desirable for the fabrication of hierarchical, complex and multifunctional devices. Here, PdAg alloys have been controllably grown at different locat... Controllable growth of high-quality hybrid nanostructures is highly desirable for the fabrication of hierarchical, complex and multifunctional devices. Here, PdAg alloys have been controllably grown at different locations on gold nanorods, producing dumbbell-like nanostructures with PdAg at the ends of the gold nanorods or branched nanostructures with PdAg grown almost perpendicular to the gold nanorods. The nucleation sites of PdAg alloys on the gold nanorods can be effectively tuned by varying the concentrations of H2PdC14, AgNO3 and cetyltrimethylammonium bromide (CTAB). The dumbbell-like and branched nanostructures were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), line-scanning energy-dispersive X-ray spectros-copy (EDS), X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy. Their electrocatalytic performance was evaluated using ethanol oxidation as a probe reaction. The dumbbelMike nanostructures show a better anti-poisoning performance, but a worse electrochemical activity than the branched ones. The results provide guidelines for the controlled growth of complicated nanostructures for either fundamental studies or potential applications. 展开更多
关键词 NANOSTRUCTURES hybrid materials METALS controlled growth electrochemical catalysis optical properties
原文传递
Success of native and invasive plant congeners depends on inorganic nitrogen compositions and levels 被引量:2
13
作者 Xi-Mei Geng Wei-Ming He 《Journal of Plant Ecology》 SCIE CSCD 2021年第2期202-212,共11页
Aims Successful plant invaders usually exhibit three strategies:Jack-of-all-trades(more robust in stressful sites),Master-of-some(more responsive in favorable sites)and Jack-and-master(both robustness and responsivene... Aims Successful plant invaders usually exhibit three strategies:Jack-of-all-trades(more robust in stressful sites),Master-of-some(more responsive in favorable sites)and Jack-and-master(both robustness and responsiveness).To revisit these strategies,we examined how soil inorganic nitrogen(N)compositions and levels influence the success of native and invasive plant congeners in the context of plant communities.Methods We conducted an experiment involving three fixed factors:species origin,N composition and N level.Here,we selected 21 plant species(eight pairs of invasive and native congeners and five non-congeneric natives)to assemble plant communities,which were subject to nine N environments consisting of three N compositions(3:1,2:2 and 1:3 NO3−/NH4+)and three N levels(low,medium and high N).We determined the following metrics:total biomass,relative biomass(a proxy of species success),mortality rate and mortality time.Important Findings Across nine N environments,native and invasive congeners exhibited similar total biomass,relative biomass and mortality time,but invaders had a marginally lower mortality rate than natives.Similar success between native and invasive congeners was linked to their similar growth and tolerance.N compositions influenced mortality time and N levels affected the total biomass and relative biomass.Importantly,species origin,N composition and N level interactively affected the total biomass,relative biomass and mortality time.These findings suggest that native and invasive plant congeners may be similarly successful across different N environments,and that inorganic N compositions and levels both contribute to plant invasion success. 展开更多
关键词 congeneric comparison environmental tolerance invasion strategy nitrogen availability plant growth
原文传递
Overweight and obesity versus concentrations of VEGF-A, sVEGFR-1, and sVEGFR-2 in plasma of patients with lower limb chronic ischemia
14
作者 Radoslaw WIECZóR Anna Maria WIECZóR +6 位作者 Grazyna GADOMSKA Katarzyna STANKOWSKA Jacek FABISIAK Karol SUPPAN Grzegorz PULKOWSKI Jacek BUDZYNSKI Danuta ROSC 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2016年第11期842-849,共8页
Objective: Being overweight or obese comprises a significant risk factor for atherosclerosis. Fat tissue also generates factors stimulating angiogenesis, the process by which new blood vessels form. The purpose of th... Objective: Being overweight or obese comprises a significant risk factor for atherosclerosis. Fat tissue also generates factors stimulating angiogenesis, the process by which new blood vessels form. The purpose of this paper is to assess concentrations of the vascular endothelial growth factor A (VEGF-A) and its soluble type-1 and type-2 re- ceptors (sVEGFR-1 and sVEGFR-2) in plasma of patients with peripheral arterial disease (PAD) depending on the level of nutrition according to body mass index (BMI). Methods: The study group included patients suffering from symptomatic PAD (n=46) in Fontaine classes Ila-lV without any history of neoplastic disease and who have a normal BMI (n=15), are overweight (n=21) or are obese (n=10). The control group (n=30) consisted of healthy non-smoking volunteers who were neither overweight nor obese. Venous blood plasma samples were collected from both groups at rest in the morning to determine plasma concentrations of VEGF-A, sVEGFR-1, and sVEGFR-2 using the enzyme- linked immunosorbent assay (ELISA) method. Results: The group of patients with PAD co-existent with being over- weight or obese tended to have higher mean concentration levels of VEGF-A and sVEGFR-2 when compared with patients suffering from PAD with normal BMIo A statistically significant positive correlation was obtained between BMI and average plasma concentrations of sVEGFR-2 (R=0.37, P=-0.0103). However, no significant correlation was no- ticed between BMI and VEGF-A or sVEGFR-1 concentrations. Conclusions: A positive correlation determined be- tween the level of antiangiogenic factor and BMI value may be indicative of the linearly growing prevalence of some antiangiogenic factors in patients with metabolic disorders, which may be one of numerous factors contributing to incomplete efficiency of collateral circulation development in patients with PAD. 展开更多
关键词 OVERWEIGHT Obesity Angiogenesis Vascular endothelial growth factor Soluble type-1 and type-2receptors Peripheral arterial disease
原文传递
Uniform single-layer graphene growth on recyclable tungsten foils
15
作者 Zhiyu Zou Xiuju Song +3 位作者 Ke Chen Qingqing Ji Yanfeng Zhang Zhongfan Liu 《Nano Research》 SCIE EI CAS CSCD 2015年第2期592-599,共8页
To meet the rising demand of graphene in electronics and optoelectronics, developing an efficient synthesis strategy for effective control of the layer thickness is highly necessary. Herein, we report the synthesis of... To meet the rising demand of graphene in electronics and optoelectronics, developing an efficient synthesis strategy for effective control of the layer thickness is highly necessary. Herein, we report the synthesis of strictly single- layer graphene on the foil of an early transition metal, tungsten (W), via a simple chemical vapor deposition route. The cracking of hydrocarbons is facilitated by the catalytically active metal surface of W, while the subsequent two-dimensional growth is mediated by the carbide-forming ability within the underlying bulk, leading to the formation of uniform monolayer graphene. The as-grown graphene layers can be transferred onto target substrates rapidly through the recently developed electrochemical method, which also allows for reuse of the substrates at least five times without introducing quality deteriora- tion. Moreover, considering the refractory nature of W foils, a complementary component of nickel is added, by means of which the growth temperature of graphene can be significantly reduced. In brief, a highly-efficient and low-cost synthesis route has been developed for the growth of graphene towards large-area uniformity, single-layer thickness and high crystalline quality. 展开更多
关键词 GRAPHENE chemical vapor deposition single layer TUNGSTEN CARBIDE recyclable substrate
原文传递
Effects of soil nitrogen levels on growth and defense of the native and introduced genotypes of alligator weed 被引量:2
16
作者 Mu Liu Fang Zhou +2 位作者 Xiaoyun Pan Zhijie Zhang Bo Li 《Journal of Plant Ecology》 SCIE CSCD 2022年第3期461-472,共12页
Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,... Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,and whether the effects differ between native and introduced populations of invasive plants.We performed a greenhouse experiment with introduced(the USA)and native(Argentina)genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth,constitutive and herbivore(Agasicles hygrophila)-induced chemical defense,and herbivory tolerance.We measured total biomass,elongation rate(as proxy of growth rate),carbon and nitrogen,and the concentration of triterpenoid saponins(defensive chemicals)in leaves and roots.Constitutive resistance(+33%higher leaf triterpenoid saponins in control treatment at low nitrogen level)and tolerance[less decreased total biomass after herbivory treatment(−24%and−15%for high and low nitrogen levels)]were favored at lower nitrogen level,while induced resistance was favored at higher nitrogen level(+24%increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level).Constitutive resistance and tolerance exhibited trade-offs with growth rate,while induced resistance positively correlated with growth rate.Additionally,the introduced genotypes had−6%lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level,but such difference was absent at high nitrogen level.Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant,and interweave with herbivory to determine the performance of introduced genotypes. 展开更多
关键词 Alternanthera philoxeroides Agasicles hygrophila growth–differentiation balance hypothesis phenotypic plasticity plant–herbivore interactions plant invasion
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部