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991.
992.
993.
目的 探讨低钾血症在颅脑创伤患者中的发病情况及其与预后的关系。方法 2010 年6月至2013 年6 月共有168 例住院期间出现低钾血症且年龄≥18 岁的颅脑创伤患者纳入研究。依据低钾血症严重程度的不同,将患者分成轻度组(3.00mmol/L≤血钾<3.50mmol/L)、中度组(2.50mmol/L≤血钾<3.00mmol/L)和重度组(血钾<2.50mmol/L),各组均采用患者血钾的最低值进行数据分析。高钠血症和低磷血症分别被定义为血钠>147.00mmol/L 和血磷<0.80mmol/L。结果 受试患者的血钾在1.10~3.40mmol/L,平均2.90mmol/L。当血钾出现最低值时,与其余两组比较,重度组患者具有更高的血钠和更低的血磷水平(均P<0.01)。与轻度组(10.5%)或中度组(25.7%)相比,重度组患者的病死率(82.1%)显著上升(均P<0.01)。多变量逻辑回归分析结果显示,低格拉斯哥昏迷评分(OR=1.28,95%CI=1.12~1.42,P<0.01)、低血钾(OR=5.57,95%CI=2.76~10.93,P<0.01)、低血磷(OR=2.76,95%CI=1.11~7.25,P<0.01)以及高血尿素氮(OR=1.16,95%CI=1.07~1.24,P<0.01)是导致患者死亡的独立危险因素。结论 颅脑创伤患者是出现低钾血症的高危人群,重度低钾血症的患者更容易合并高钠血症和低磷血症。重度低钾血症和低磷血症是颅脑创伤患者死亡的独立危险因素。 相似文献
994.
We investigate the stability and phase transition of localized modes in Bose–Einstein Condensates (BECs) in an optical lattice with the discrete nonlinear Schrödinger model by considering both two- and three-body interactions. We find that there are three types of localized modes, bright discrete breather (DB), discrete kink (DK), and multi-breather (MUB). Moreover, both two- and three-body on-site repulsive interactions can stabilize DB, while on-site attractive three-body interactions destabilize it. There is a critical value for the three-body interaction with which both DK and MUB become the most stable ones. We give analytically the energy thresholds for the destabilization of localized states and find that they are unstable (stable) when the total energy of the system is higher (lower) than the thresholds. The stability and dynamics characters of DB and MUB are general for extended lattice systems. Our result is useful for the blocking, filtering, and transfer of the norm in nonlinear lattices for BECs with both two- and three-body interactions. 相似文献
995.
Xiaodong Xu Lifen Zhang Jian Zhou Jun Wang Jinghua Yin Jinliang Qiao 《Journal of Macromolecular Science: Physics》2015,54(1):32-44
The thermal behaviors of glycidyl methacrylate (GMA)-grafted polypropylene (PP) (PP-g-GMA) with two different grafting degrees, namely, GPP1 and GPP2, were investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA), and thermogravimetrical analysis (TGA). DSC results suggested that the GMA grafted PP exhibited higher crystallization temperature Tc, higher melting temperature Tm, and higher crystallinity compared with the neat PP. The isothermal crystallization kinetics was analyzed with the Avrami equation and the total crystallization activation energy was calculated. It was concluded that the crystallization processes of PP and the grafted PP were controlled by nucleation and the values of the crystallization activation energy of PP and the grafted PP were almost identical. POM results suggested that the GMA grafted PP exhibited smaller spherulites size compared with the neat PP. WAXD patterns indicated that the neat PP encouraged the formation of γ phase, compared with the grafted PP, during the crystallization process. DMA results showed that melt grafting did not induce a clear effect on the γ-transition and β-transition of the amorphous phase but resulted in a decrease in mobility of the PP chains in the crystals. TGA curves suggested that the melt grafting slightly improved the thermal stability of PP. 相似文献
996.
该文对一类对称三次Hamilton系统在非光滑对称摄动下产生的极限环数目进行研究.通过多参数摄动理论和定性分析方法,得到这类在非光滑摄动下的三次系统可以存在至少19个极限环. 相似文献
997.
In this paper, we study the commutativity of Toeplitz operators with radial symbols on the pluriharmonic Bergman space. We obtain the necessary and sufficient conditions for the commutativity of bounded Toeplitz operator and Toeplitz operator with radial symbol on the pluriharmonic Bergman space. 相似文献
998.
Emamectin benzoate, a macrocyclic lactone, can be used in low quantities to control arthropod pests, effectively. However, its poor photostability prevents its further use. To delay its photodegradation, novel acrylate‐type polymeric nanoparticles were synthesized and tested as materials for improving pesticide photostability. N‐acylated emamectin benzoate was synthesized via bonding emamectin benzoate to acrylamide. The resulting pesticide, containing the double bond linkage –C=C–N–, was copolymerized with butyl acrylate and methyl methacrylate by the emulsion polymerization method. The refined polymers were characterized by Fourier transform infrared spectroscopy spectroscopy, and result illustrated the pesticide was conjugated to the polymers. Atomic force microscope and dynamic light scattering analyses were also used for determining the average particle diameters of pesticide–polymer conjugates. Photostability tests showed that the nanoparticles obtained exhibited greatly improved photostability. Additionally, the laboratory toxicity tests demonstrated that the insecticidal effects of the novel emamectin benzoate formulation were better than those of the control pesticide formulation (emamectin benzoate EC). Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
999.
Copolymers of pentafluorophenylhexafluoroisopropyl methacrylate (FPPMA) with trifluoroethyl methacrylate (TFEMA) were prepared in THF solution and in bulk using azobisisobutyronitrile as a free radical initiator. The monomer reactivity ratios of TFEMA (M1) and FPPMA (M2) were calculated as r1 = 0.55 and r2 = 0.07. The refractive indices of poly(TFEMA) and poly(FPPMA) are very similar as 1.435 and 1.430, respectively, at 532 nm, and the copolymer films were transparent. The glass transition temperatures (Tg) of the copolymers were in the range of 80–90°C and showed a negative deviation from the Gordon–Taylor equation. The thermal decomposition temperature (Td) was increased with the content of FPPMA in copolymers. Low water absorption for 1:1 FPPMA/TFEMA copolymer was detected. Copolymers of FPPMA with hexafluoroisopropyl methacrylate (HFPMA) were also prepared. The monomer reactivity ratios of HFPMA (M1) and FPPMA (M2) were calculated as r1 = 0.43 and r2 = 0.10. The Tgs of the copolymers were in the range of 88–95°C and showed also a negative deviation from the Gordon–Taylor equation. Tg and Td of the copolymers were increased with the content of FPPMA. The refractive index of poly(HFPMA) (1.384 at 532 nm) is much lower than that of FPPMA homopolymer, but copolymer films obtained were clear and transparent. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
1000.
The polysiloxane-based alicyclic episulfide resin (PSCER) was synthesized through substitution of oxygen atoms in 1,3-bis[2-(3{7-oxabicyclo[4,1,0]hepyl})ethyl]-tetramethyldisiloxane with sulfur atoms using potassium thiocyanate (KSCN) as the reagent. The product was purified by column chromatography, and the by-products were isolated. It was found by 1H-NMR and 13C-NMR that the by-products were cycloolefins formed by desulfurization of the episulfide groups. PSCER was unstable; desulfurization took place easily, especially at high temperatures. The PSCER resin could not be cured with methylhexahydrophthalic anhydride (MeHPPA). When m-phenylenediamine or isophorondiamine was used as curing agent, PSCER showed a higher reactivity compared with the parent epoxide. However, the reactivity of the alicyclic episulfide was much lower than the polysiloxane based aliphatic episulfide for the steric hindrance of the six member ring. Desulfurization took place upon curing of the alicyclic episulfide resin, therefore the cured resin showed poor mechanical properties. Thermal stability of cured PSCER resin was also poor on account of low bonding energy of C-S and crosslinking density. 相似文献