求极限的等价无穷大代换

给出等价无穷大代换的法则,并由此得到求某些未定式极限的计算方法.     

Radiation dose measurements for staff members involved in holmium-166 preclinical trial

AimNeutron-activated holmium-166 (¹⁶⁶Ho) is an excellent radionuclide for internal radiation therapy (Eβmax = 1.84 MeV) with an appropriate half-life (26.8 h), which emits photons (81 keV, 6.2%) suitable to be detected by gamma cameras. Preparing and injecting radiopharmaceuticals containing beta/gamma emitting holmium-166 implies a risk of exceeding the upper limit for skin and hand radiation equivalent doses (500 mSv/an). This study was aimed to estimate the whole body and finger exposure for staff responsible for dose preparation, dose dispensing, and dose injection of holmium-166 therapy.MethodsTo measure the finger dose from external exposure, all staff members wore TLD dosimeters. Personal dose equivalents Hp(10) were measured using electronic personal dosimeters (EPD MK2, Thermo Fischer Scientific) placed on the left side of the chest. During our study, staff members administered more than 40 ¹⁶⁶Ho-based therapies for preclinical trial. Appropriate radiation safety procedures and shielding were applied at each stage.ResultsIn this study, the whole body doses were 2.80 ± 1.56 nSv MBq⁻¹ for one ¹⁶⁶Ho-therapy preparation/formulation, and 2.68 ± 1.70 nSv MBq⁻¹ for one intravenous injection. Maximum finger doses were 2.9 ± 0.2 μSv MBq⁻¹ and 2.5 ± 0.3 μSv MBq⁻¹ for preparation and injection, respectively (activities injected: 72 ± 3 MBq).ConclusionExtrapolated annual doses from 300 ¹⁶⁶Ho radionuclide therapies were lower than the annual limit doses for skin and the whole body, 500 mSv and 20 mSv, respectively, reported in the European Directive EURATOM 96/29 when applying appropriate radiation protection standards. However, these doses have to be added to other diagnostic or therapeutic protocols, performed in preclinical facilities.     

S-烷基异硫脲盐作为硫醇替代物经环氧开环反应合成β-羟基硫化物

S-烷基异硫脲盐作为一种无毒、无味、易于制备的硫醇替代物，在碱性水介质中、室温下与多种环氧化合物发生环氧开环反应，区域选择性、高收率地合成了一系列β-羟基硫化物。     

Chromatic Uniqueness of a Family of K_4-Homeomorphs

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ａｌｌｇｒａｐｈｓｃｏｎｓｉｄｅｒｅｄｉｎｔｈｉｓｐａｐｅｒａｒｅｆｉｎｉｔｅ,ｕｎｄｉｒｅｃｔｅｄ ,ｕｎｌｏｏｐｅｄａｎｄｓｉｍｐｌｅｇｒａｐｈｓ.ＷｅｄｅｎｏｔｅｔｈｅｃｈｒｏｍａｔｉｃｐｏｌｙｎｏｍｉａｌｏｆａｇｒａｐｈＧｂｙＰ(Ｇ ,λ)ｏｒＰ(Ｇ) .ＷｅｓａｙｇｒａｐｈｓＧａｎｄＨｔｏｂｅｃｈｒｏｍａｔｉａｌｌｙｅｑｕｉｖａｌｅｎｔｉｆＰ(Ｇ) =Ｐ(Ｈ) .ＴｈｅｃｈｒｏｍａｔｉｃｕｎｉｑｕｅｎｅｓｓｏｆａｇｒａｐｈＧｉｓｅｓｔａｂｌｉｓｈｅｄｉｆｉｔｃａｎｂｅｄｅｄ…     

A theoretical study of some problems on low-noise pyroelectric detector-amplifier systems

The configurations of the coupling network, which can effectively aecrease the effect of the noise sources within the amplifier on the equivalent input noise of the whole pyroelectric detector-amplifier system, are studied. The influences of feedback upon the noise properties of the basic amplifiers are analyzed. The procedures of designing low-noise pyroelectric detector-amplifier systems are followed.     

Equivalent Model, Error Analysis, and Design Steps of AGC Loop for MM-Wave Receiver

Automatic Gain Controlled (AGC) Loops are used in MM-Wave receiver in wide-ranging. In this paper, the equivalent model and loop equation of AGC Loop are built, the loop errors are analyzed and then the design steps of AGC Loop are given out.     

量子隧穿中的等效势垒

本文给出等效垫垒的概念及性质，利用等效势垒的性质可以使量子遂穿中的有关问题更容易解决。     

大剂量补充微量元素治疗“胃溃疡型腺癌伴广泛转移”一例

阐述了一例胃底溃疡型腺癌伴周边器官淋巴组织广泛转移患者，行“贲门MT术”姑息治疗后，经九个月大剂量多种微量元素制剂补充达到很好的临床效果。     

Dynamic electrochemical impedance spectroscopy of the adsorption and relaxation of polyaniline chains during potentiodynamic redox transformations

A new approach to an equivalent circuit analysis of impedance spectra of a conducting polyaniline (PAni) layer is presented. Film properties are often modeled by constant-phase elements (CPE), which are closer to experimental results than capacitors. We want to take an insight into the CPE. We propose a novel equivalent circuit based on the Frumkin-Melik-Gaikazyan adsorption model, as we suppose that the PAni layer molecules may behave like other adsorbing and relaxing organic compounds. Measurements are performed using recently developed experimental technique—dynamic electrochemical impedance spectroscopy. Obtained spectra are analyzed using the proposed equivalent circuits. Characteristics of several parameters are analyzed and discussed. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 9, pp. 1111–1119. The text was submitted by the authors in English.