为了揭示稻渔种养系统生产潜力和制定高产高效栽培措施提供科学依据。从中国知网和web of science等2个数据库,分别以稻渔(包括稻虾、稻鱼、稻蟹、稻鳖、稻鳅)、施肥、产量、种植密度、种植方式、rice-fish、rice-crayfish、rice-crab、...为了揭示稻渔种养系统生产潜力和制定高产高效栽培措施提供科学依据。从中国知网和web of science等2个数据库,分别以稻渔(包括稻虾、稻鱼、稻蟹、稻鳖、稻鳅)、施肥、产量、种植密度、种植方式、rice-fish、rice-crayfish、rice-crab、rice-turtle、rice-loach、yield、variety、seeding density、planting pattern、fertilizer and China等为关键词检索,共收集目标文献108篇。总结稻渔系统水稻的产量潜力和产量差,通过分析品种、施肥量、种植密度、种植方式和饲料氮磷残留对稻渔系统水稻产量的影响,阐明稻渔种养系统水稻产量差的影响因素及缩小产量差的途径。结果表明,当前我国稻渔系统产量潜力较大,稻虾、稻鱼、稻蟹、稻鳖、稻鳅模式水稻高产纪录分别为9.64、9.46、10.47、9.14、9.62 t/hm^(2),总样本平均产量分别实现了潜力产量的79%、75%、76%、74%、78%,其中水稻品种、种植密度和施肥量是产量差的主要限制因素。稻虾模式氮磷钾最优施肥量分别为86.2、69.2、66.5 kg/hm^(2),稻鱼模式分别为151.3、45.7、108.0 kg/hm^(2);杂交稻的稻虾、稻鱼、稻鳖和稻鳅模式水稻产量比常规稻增加3.9%~50.6%;籼稻产量在稻虾、稻鱼、稻鳖和稻鳅模式下比粳稻增加4.6%~25.6%。稻虾、稻鱼、稻蟹和稻鳅系统水稻的适宜种植密度分别为32.2万、30.2万、24.7万、45.1万株/hm^(2);另外,一定量饲料氮磷残留可提高水稻产量。我国稻虾、稻鱼、稻蟹、稻鳖、稻鳅模式下水稻的增产潜力分别为2.07、2.39、2.50、2.37、2.15 t/hm^(2)。适宜的品种、施肥量、播种密度和饲料氮磷残留量可以缩小产量差,其中品种以籼稻和杂交稻为宜;优化施肥量可以使稻虾和稻鱼模式下水稻分别增产5.5%、5.1%;优化种植密度则使水稻增产4.8%~15.5%。展开更多
The pore structure characteristics of high-sulfur coal from Wansheng in Chongqing have been studied by a nitrogen adsorption method （BET）. The effects of grinding and pre-treating with nitric acid on the inorganic s...The pore structure characteristics of high-sulfur coal from Wansheng in Chongqing have been studied by a nitrogen adsorption method （BET）. The effects of grinding and pre-treating with nitric acid on the inorganic sulfur content of coal have been investigated. Organic sulfur in coal pretreated with nitric acid was desulfurized by using propylene-glycol-KOH （PG-KOH）. Fractal kinetic properties of these two desulfurization procedures were investigated by using fractal geometric theory. The results show that both the specific surface area and pore volume increased with the decrease in particle diameter. The microspore surface of coal had fractal characteristics; the fractal dimension was 2.48. The sulfur content decreased with the decrease in particle diameter by grinding. After pretreatment with nitric acid, the desulfurization ratio （DFR） of inorganic sulfur increased to over 99% and the DFR of total sulfur to over 70%. The desulfurization procedure of inorganic sulfur had fractal kinetic characteristics; its reactive frac- tal dimension was 2.94. The organic sulfur desulfurization procedure by PG-KOH was also tallied with fractal kinetic properties; the reactive fracta! dimension was 2.57. The effect of temperature on the desul- furization ratio of organic sulfur can be described with an Arrhenius empirical equation. The rate constant, pre-exponential factor and the activation energy of the reaction increased with the decrease in particle diameter.展开更多
目的利用高分辨磁共振成像(high-resolution magnetic resonance imaging,HR-MRI)对轻、重度基底动脉(basilar artery,BA)弯曲的患者间斑块分布、大小及成分的差异进行研究。材料与方法经三维时间飞跃法磁共振血管造影(three-dimension ...目的利用高分辨磁共振成像(high-resolution magnetic resonance imaging,HR-MRI)对轻、重度基底动脉(basilar artery,BA)弯曲的患者间斑块分布、大小及成分的差异进行研究。材料与方法经三维时间飞跃法磁共振血管造影(three-dimension time of flight magnetic resonance angiography,3D-TOF-MRA),将BA弯曲的患者纳入研究。测量BA最大弯曲处的血管外壁到BA两端(BA顶部与左右椎动脉汇合处的连接线)的横向距离,分为轻度弯曲组(5 mm<横向距离<10 mm)和重度弯曲组(横向距离≥10 mm)。比较两组的临床相关因素、BA斑块分布(内弧、外弧)、大小(微小斑块、明显斑块)及成分[斑块内出血(intraplaque hemorrhage,IPH)]有无差异。结果92例患者纳入研究,共计106个斑块。轻度弯曲组54例,BA斑块60个;重度弯曲组38例,BA斑块46个。两组间BA斑块均常见于内弧(内弧与外弧:76.7%、73.9%与23.3%、26.1%);重度弯曲组中明显斑块所占比例较轻度弯曲组大(重度与轻度:65.2%与36.7%),差异具有统计学意义(P=0.004);重度弯曲组中IPH所占比例较轻度弯曲组大(重度与轻度:69.6%与25.0%),差异具有统计学意义(P<0.001),两组临床相关因素差异均无统计学意义(P均>0.05)。结论弯曲的基底动脉粥样硬化斑块多分布于内弧。基底动脉重度弯曲组较轻度弯曲组斑块更明显,且重度弯曲组中IPH所占比例较轻度弯曲组大,轻度弯曲组斑块相对来说更稳定。展开更多
文摘The pore structure characteristics of high-sulfur coal from Wansheng in Chongqing have been studied by a nitrogen adsorption method （BET）. The effects of grinding and pre-treating with nitric acid on the inorganic sulfur content of coal have been investigated. Organic sulfur in coal pretreated with nitric acid was desulfurized by using propylene-glycol-KOH （PG-KOH）. Fractal kinetic properties of these two desulfurization procedures were investigated by using fractal geometric theory. The results show that both the specific surface area and pore volume increased with the decrease in particle diameter. The microspore surface of coal had fractal characteristics; the fractal dimension was 2.48. The sulfur content decreased with the decrease in particle diameter by grinding. After pretreatment with nitric acid, the desulfurization ratio （DFR） of inorganic sulfur increased to over 99% and the DFR of total sulfur to over 70%. The desulfurization procedure of inorganic sulfur had fractal kinetic characteristics; its reactive frac- tal dimension was 2.94. The organic sulfur desulfurization procedure by PG-KOH was also tallied with fractal kinetic properties; the reactive fracta! dimension was 2.57. The effect of temperature on the desul- furization ratio of organic sulfur can be described with an Arrhenius empirical equation. The rate constant, pre-exponential factor and the activation energy of the reaction increased with the decrease in particle diameter.
文摘目的利用高分辨磁共振成像(high-resolution magnetic resonance imaging,HR-MRI)对轻、重度基底动脉(basilar artery,BA)弯曲的患者间斑块分布、大小及成分的差异进行研究。材料与方法经三维时间飞跃法磁共振血管造影(three-dimension time of flight magnetic resonance angiography,3D-TOF-MRA),将BA弯曲的患者纳入研究。测量BA最大弯曲处的血管外壁到BA两端(BA顶部与左右椎动脉汇合处的连接线)的横向距离,分为轻度弯曲组(5 mm<横向距离<10 mm)和重度弯曲组(横向距离≥10 mm)。比较两组的临床相关因素、BA斑块分布(内弧、外弧)、大小(微小斑块、明显斑块)及成分[斑块内出血(intraplaque hemorrhage,IPH)]有无差异。结果92例患者纳入研究,共计106个斑块。轻度弯曲组54例,BA斑块60个;重度弯曲组38例,BA斑块46个。两组间BA斑块均常见于内弧(内弧与外弧:76.7%、73.9%与23.3%、26.1%);重度弯曲组中明显斑块所占比例较轻度弯曲组大(重度与轻度:65.2%与36.7%),差异具有统计学意义(P=0.004);重度弯曲组中IPH所占比例较轻度弯曲组大(重度与轻度:69.6%与25.0%),差异具有统计学意义(P<0.001),两组临床相关因素差异均无统计学意义(P均>0.05)。结论弯曲的基底动脉粥样硬化斑块多分布于内弧。基底动脉重度弯曲组较轻度弯曲组斑块更明显,且重度弯曲组中IPH所占比例较轻度弯曲组大,轻度弯曲组斑块相对来说更稳定。
