一种电流模式多功能滤波器结构

提出了一种简单的电流模式多功能滤波器结构，具有一个输入端和三个输出端，可以实现低通，高通，带通，全通和陷波功能，不需要任何严格匹配关系，该结构中使用了６个ＣＣ器件，两个接地电阻和两个接地电容，结构十分简单且无源灵敏度很低。     

福建土壤对酸沉降的相对敏感性评价与区划

选择母岩、土壤类型、土地利用和降雨量 4个生态因子 ,应用半定量化方法对其进行类目划分和权重 ,综合评价了福建省土壤对酸沉降的相对敏感性 ,并应用地理信息系统进行了区划 .由于福建省风化缓慢的硅质岩所占的比例较大 ,土壤大多呈酸性至微酸性反应 ,降水丰富 ,加之针叶林面积大 ,所以全省有 60 %以上面积的土壤显示出较大的敏感性等级 (5～ 7级 )     

UV-absorbing compounds and susceptibility of weedy species to UV-B radiation

Stratospheric ozone (O₃) depletion has led to increased terrestrial ultraviolet‐B (UV‐B) radiation (290–320 nm). Leaves exposed to this radiation produce UV‐absorbing compounds in the epidermal cells, which protect plants from UV‐B damage. To determine the role of UV‐absorbing compounds in the UV‐B sensitivity of weeds (common chickweed (Stellaria media), downy brome (Bromus tectorum), green smartweed (Polygonum scabrum), redroot pigweed (Amaranthus retroflexus), spotted cat’s‐ear (Hypochoeris radicata), and stork’s‐bill (Erodium cicutarium)) seedlings were exposed to 0, 4 (field ambient), 7 (18% O₃ depletion) and 11 (37% O₃ depletion) kJ m^?2 d^?1 of biologically effective UV‐B radiation in a greenhouse. Ultraviolet‐absorbing compounds were extracted from the second true‐leaf (0.5 cm² samples) with methanol : distilled water : HCl (79 : 20 : 1) in an 85°C water bath for 15 min, and the absorbance of the extracts measured at 300 nm. The shoot dry biomass was recorded to determine the susceptibility to UV‐B radiation. Common chickweed was the most sensitive and green smartweed the least sensitive weed to UV‐B radiation. The latter accumulated more UV‐absorbing compounds and this accumulation occurred earlier compared with common chickweed. As UV‐B_BE radiation levels increased from 0 to 11 kJ m^?2 d^?1, the green smartweed shoot biomass did not decline. However, the biomass of all five susceptible species declined despite an increase in the UV‐absorbing compounds in response to increased UV‐B radiation. Therefore, formation of a ‘UV‐screen’ in these species is not sufficient to fully prevent UV‐B damage. When the concentration of UV‐absorbing compounds in the six species was plotted against their susceptibility to UV‐B radiation, no relationship was observed. Thus, while the accumulation of UV‐absorbing compounds may be a major factor in the protection of certain species against UV‐B radiation and may offer some degree of defence in other species, it does not explain UV‐B susceptibility differences in weedy species in general.     

Effects of the sodium‐glucose cotransporter 2 (SGLT2) inhibitor velagliflozin,a new drug with therapeutic potential to treat diabetes in cats

Sodium‐glucose cotransporter 2 (SGLT2) inhibitors are used in the treatment of human diabetics. They increase glucose excretion and correct hyperglycemia. We examined the investigational SGLT2 inhibitor velagliflozin in two groups of six neutered adult obese cats (equal gender distribution). Placebo (Pl) or drug (D; 1 mg/kg) was administered for 35 days. Routine blood examinations, fructosamine, beta‐hydroxybutyrate (BHB), nonesterified fatty acids (NEFA), glucagon, adiponectin, and leptin were measured before and after treatment, also water intake, and urinary electrolytes, glucose, and volume. Indirect calorimetry, an intravenous glucose tolerance test (IVGTT; 0.8 g/kg) and insulin tolerance test (IVITT) were conducted. All cats tolerated treatment well. Significant changes with D included a decrease in the respiratory exchange ratio, an increase in cholesterol, a small increase in albumin, and a rise in BHB and NEFA. Glucose clearance was unaltered, although less insulin was secreted during the IVGTT (p = .056) suggesting improved insulin sensitivity. IVITT was unchanged. Treatment did not affect glucagon, leptin, or adiponectin. Water intake, urine output, urinary glucose excretion, and the glucose/creatinine ratio but not urinary electrolytes were significantly higher post‐D. We conclude that velagliflozin is a promising drug, which increases urinary glucose excretion in cats and could thereby be beneficial for the treatment of hyperglycemia.     

黄瓜霜霉病菌对双炔酰菌胺的敏感基线及其抗性突变体生物学性状研究

为建立黄瓜霜霉病菌对双炔酰菌胺的敏感基线及评估其抗性风险,采用叶盘漂浮法测定了采自河北、山东未使用过羧酸酰胺类(CAAs)药剂地区的69株黄瓜霜霉病菌(Pseudoperonospora cubensis)对双炔酰菌胺的敏感性,并对黄瓜霜霉病菌抗双炔酰菌胺突变体的获得方法及突变体的生物学性状进行了研究。结果表明:69株黄瓜霜霉病菌对双炔酰菌胺的平均EC50值为(0.358±0.144)μg/mL,不同敏感性菌株的频率呈连续单峰曲线分布,未发现敏感性下降的亚群体,因此可将其作为黄瓜霜霉病菌对双炔酰菌胺的敏感基线;通过药剂驯化的方法未获得黄瓜霜霉病菌抗双炔酰菌胺的突变体;而通过紫外诱导的方法获得了6个抗双炔酰菌胺的突变体,其抗性水平介于5.74~22.96倍之间,突变频率为1.09×10-7,适合度显著低于其亲本菌株,且抗药性不能稳定遗传;双炔酰菌胺与甲霜灵、嘧菌酯、霜脲氰、氟吡菌胺之间无交互抗性关系,与烯酰吗啉之间有交互抗性关系。据此推测黄瓜霜霉病菌对双炔酰菌胺的抗性风险为低到中等。     

小菜蛾和绒茧蜂乙酰胆碱酯酶对甲胺磷和甲基异柳磷敏感性监测

对 ACh E的 K m、Vmax和 Ki值的研究结果表明 ,田间小菜蛾和绒茧蜂对甲胺磷和甲基异柳磷的抗性与 ACh E对杀虫剂的不敏感性有关。田间监测结果表明 ,每年 9月至次年 2月期间 ,由于田间杀虫剂选择压较高 ,小菜蛾 ACh E对有机磷较不敏感 ,而在每年的 6月至 8月期间 ,ACh E敏感性有所升高 ,达到全年的最高点。寄生于同一虫源的绒茧蜂 ACh E敏感性的变化也呈明显的相关性。绒茧蜂 ACh E的敏感性显著高于小菜蛾 ,尚未达到高度不敏感水平。当田间选择压极高时 ,可导致小菜蛾 ACh E呈高度不敏感 ,此时绒茧蜂 ACh E也表现出较高的不敏感性。     

2013年湖北省小麦赤霉病菌对多菌灵和戊唑醇的敏感性

2013年从湖北省7个小麦主产区分离获得106株禾谷镰刀菌,测定了其对戊唑醇和多菌灵的敏感性。结果表明:戊唑醇和多菌灵对所有供试菌株的EC50值分别为0.064~0.778和0.090~0.858 mg/L。采用SAS软件的W法对EC50分布进行了正态性检验,表明106株菌株对戊唑醇和多菌灵敏感性的频率分布符合正态分布,其EC50平均值分别为(0.383±0.129)和(0.526±0.151)mg/L。不同地区来源的菌株对两种药剂的敏感性存在显著差异,其中襄阳的菌株对两种药剂的敏感性显著低于其他6个地区的。研究结果显示:湖北省小麦赤霉病菌未出现对戊唑醇和多菌灵抗性菌群,两种药剂用于防治小麦赤霉病仍具有使用价值。     

辽宁省不同地区番茄灰霉病菌对咯菌腈的敏感性

为明确辽宁省不同地区间番茄灰霉病菌对咯菌腈的敏感性是否存在差异,以及咯菌腈与其他杀菌剂之间是否存在交互抗性,采用菌丝生长速率法测定番茄灰霉病菌对咯菌腈、腐霉利、多菌灵的敏感性。结果表明,从辽宁省6个不同地区分离的番茄灰霉病菌菌株对咯菌腈的平均EC50差异不显著,番茄灰霉病菌菌株对咯菌腈的敏感性频率呈正态分布,咯菌腈对不同地区共117株番茄灰霉病菌的EC50平均值为(0.007 3±0.004 5)μg/mL,且咯菌腈与腐霉利和多菌灵之间均不存在交互抗药性。     

河南省小麦纹枯病菌对三唑酮的敏感性

正小麦纹枯病是一种世界分布的土传真菌病害。近年来该病在我国冬小麦种植区发生普遍,已成为小麦高产、稳产的重大障碍~([1])。河南省是我国小麦主产区之一,近几年小麦纹枯病的发生面积连续在300万hm~2左右,危害严重~([2])。目前,尚未发现高抗纹枯病的小麦品种,控制该病害主要依靠药剂种子处理结合春季喷雾来进行,所用药剂包括井冈霉素和以三唑酮为代表的三唑类化学药剂。随着     

辽宁省稻瘟病菌对肟菌酯敏感性监测

为了明确稻瘟病菌对肟菌酯的敏感性,利用菌丝生长速率法测定了 2018～2019年辽宁省11个水稻产区分离的220株稻瘟病菌对肟菌酯的敏感性,并在此基础上对供试菌株的抗药性水平进行了分析.结果表明:稻瘟病菌对肟菌酯的EC50值分布范围为0.0111～0.4983 μg·mL-1,敏感性差异达44.89倍.220株稻瘟病菌...