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891.
利用投影符技术,将多粒子体系完备的Hilbert空间分成两个相互正交的子空间,以明晰的方式导出了处于某一外界环境中的开放量子力学体系的等效哈密顿算符的一般表达式。考察了一些有实用意义的新的可解模型,通过对各种具体模型的特征多项式的分析与计算,得出了相应的开放多粒子量子体系能谱的峰位和宽度随耦合而变化的性状。 相似文献
892.
893.
894.
要真正测量高速运动物体上的原时,只考虑狭义相对论的时间膨胀效应还不够,还应该考虑到两个参照系间的信号传递所用的时间,本文导出了测量时间与运动物体上的原时的关系,并就某些参考书上的错误进行了讨论。 相似文献
895.
为进一步分析内生致热原(EP)性发热时体温升高与脑脊液环磷酸腺苷(cAMP)含量变化间的因果关系,本文观察了静脉灌注水畅酸钠对家兔EP性发热时体温升高和血浆、脑脊液cAMP含量变化的影响,证明了cAMP很可能作为重要的中枢介质参与家兔EP性发热机制。静脉注射EP后家兔脑脊液cAMP含量的增高不是体温升高的结果。EP性发热时脑脊液中增加的cAMP不可能来源于血浆。水杨酸钠的抑热环节可能在cAMP增高之后。 相似文献
896.
大孔吸附树脂对葡萄籽原花青素的吸附研究 总被引:14,自引:0,他引:14
对8种大孔吸附树脂对葡萄籽原花青素的吸附洗脱性能进行了筛选实验,并选择其中几种树脂研究其对葡萄籽原花青素的吸附特性及机理,发现NKA树脂是比较好的吸附剂。 相似文献
897.
Solar energy is the largest renewable energy source in the world and the primary energy source of wind energy, tidal energy, biomass energy, and fossil fuel. Photocatalysis technology is a sunlight-driven chemical reaction process on the surface of photocatalysts that can generate H2 from water, decompose organic contaminants, and reduce CO2 into organic fuels. As a metal-free polymeric material, graphite-like carbon nitride (g-C3N4) has attracted significant attention because of its special band structure, easy fabrication, and low costs. However, some bottlenecks still limit its photocatalytic performance. To date, numerous strategies have been employed to optimize the photoelectric properties of g-C3N4, such as element doping, functional group modification, and construction of heterojunctions. Remarkably, these modification strategies are strongly associated with the surface behavior of g-C3N4, which plays a key role in efficient photocatalytic performance. In this review, we endeavor to provide a comprehensive summary of g-C3N4-based photocatalysts prepared through typical surface modification strategies (surface functionalization and construction of heterojunctions) and elaborate their special light-excitation and response mechanism, photo-generated carrier transfer route, and surface catalytic reaction in detail under visible-light irradiation. Moreover, the potential applications of the surface-modified g-C3N4-based photocatalysts for photocatalytic H2 generation and reduction of CO2 into fuels are summarized. Finally, based on the current research, the key challenges that should be further studied and overcome are highlighted. The following are the objectives that future studies need to focus on: (1) Although considerable effort has been made to develop a surface modification strategy for g-C3N4, its photocatalytic efficiency is still too low to meet industrial application standards. The currently obtained solar-to‑hydrogen (STH) conversion efficiency of g-C3N4 for H2 generation is approximately 2%, which is considerably lower than the commercial standards of 10%. Thus, the regulation of the surface/textural properties and electronic band structure of g-C3N4 should be further elucidated to improve its photocatalytic performance. (2) Significant challenges remain in the design and construction of g-C3N4-based S-scheme heterojunction photocatalysts by facile, low-cost, and reliable methods. To overcome the limitations of conventional heterojunctions thoroughly, a promising S-scheme heterojunction photocatalytic system was recently reported. The study further clarifies the charge transfer route and mechanism during the catalytic process. Thus, the rational design and synthesis of g-C3N4-based S-scheme heterojunctions will attract extensive scientific interest in the next few years in this field. (3) First-principle calculation is an effective strategy to study the optical, electrical, magnetic, and other physicochemical properties of surface strategy modified g-C3N4, providing important information to reveal the charge transfer path and intrinsic catalytic mechanism. As a result, density functional theory (DFT) computation will be paid increasing attention and widely applied in surface-modified g-C3N4-based photocatalysts. 相似文献
898.
899.
刘建军 《广东微量元素科学》2002,9(1):39-41
为探讨非药物驱铅对铅中毒患儿的治疗效果 ,给锌原卟啉 (ZPP)值 >3 5 μg g- 1Hb的儿童服用降铅保健液 ,未服用者作为对照组。结果表明 ,服用降铅保健液组和对照组儿童 ,经过一个月后 ,ZPP值均有下降 ,服用组的ZPP值平均下降幅度达 2 2 4μg g- 1Hb ,大于对照组 (0 89μg g- 1Hb) ,差异有显著意义 (P <0 0 1 )。两组儿童均未出现肝肾功能异常 ,未有患儿诉不良反应。提示服用降铅保健液驱铅对铅中毒儿童是有效和安全的方法 相似文献
900.
采用柠檬酸三钠还原法制备了粒径约为8.0 nm的银纳米微粒, 并用于标记羊抗人纤维蛋白原. 在pH 5.8的Na2HPO4-NaH2PO4缓冲溶液中及KCl和聚乙二醇6000(PEG6000)存在下, 银标记羊抗人纤维蛋白原与纤维蛋白原发生特异性反应, 导致在465 nm处的共振散射强度降低. 纤维蛋白原浓度在0.067~1.67 μg/mL范围内与共振散射强度的降低值呈良好的线性关系, 相关系数为0.9974, 检出限为0.024 μg/mL, 用于定量测定人血浆中的纤维蛋白原, 结果比较满意. 相似文献