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191.
192.
设f是一个有穷级的超越整函数,a,b,c是3个有穷复数,满足c≠0,a≠b,且n为正整数.如果a是f的Borel例外值,且Δ_c~nf(z)与f(z)IM分担b,则f(z)=a+Ae~(Bz),其中A,B为两个非零常数. 相似文献
193.
目的 分析和探讨后腹腔镜下肾部分切除术后发生尿瘘的危险因素。方法统计和分析2004-10-2013-06 行腹
腔镜下经后腹膜路径肾部分切除术后发生尿瘘的128 例肾肿瘤患者的临床资料,尿瘘严格定义为手术2d 后仍从后腹膜引流管持续引流出尿液。结果术后有14 例(10.9%)患者发生尿瘘。发生尿瘘的患者中10 例(71.4%)未行CTA 检查,术中平均出血量(232.3±86.7)ml,平均肾动脉阻断时间(28.2±7.5)min,平均住院时间(13.1±2.1)d,9 例(64.3%)术中发现集合系统破损。单因素分析提示年龄(P =0.1102)、糖尿病(P =0.0445)、肿瘤内生型生长(P =0.0835)、术前是否行CTA 检查(P=0.0137)、集合系统损伤(P=0.0935)、肾动脉阻断时间(P =0.1225)及术中出血量(P=0.0045)是发生尿瘘的危险因素;多因素分析提示糖尿病(P =0.0381)、术前是否行CTA 检查(P =0.0433)及术中出血量(P =0.0155)是术后发生尿瘘的独立危险因素。结论糖尿病、术中出血
量及术前是否行肾脏CTA 检查是后腹腔镜下肾部分切除术后发生尿瘘的独立危险因素。减少术中出血有利于术者获得清晰的操作视野,有效缝合破损的集合系统,从而防止尿瘘的发生。 相似文献
194.
Poly(vinyl alcohol)/melamine phosphate composites (PVA/MP) as a novel halogen‐free, flame‐retardant foam matrix were prepared through thermal processing, and then their thermal stability and flame retardancy were investigated by thermo‐gravimetric analysis, micro‐scale combustion calorimeter, cone calorimeter, vertical burning test, and limiting oxygen index (LOI) test. It was found that the thermal stability and combustion properties of the PVA/MP composites could be influenced by the addition of MP. Compared with the control PVA sample (B‐PVA), in the PVA/MP (75/25) composites, the temperature at 5% mass loss (T5%) decreased about 10°C, the residual chars at 600°C increased by nearly 27%, the temperature at the maximum peak heat release rate (TP) shifted from 292°C to 452°C, and the total heat released and the heat release capacity (HRC) decreased by 28% and 14%, respectively. Moreover, the PVA/MP composites could reach LOI value up to 35% and UL94 classification V‐0, showing good flame retardancy. At the same time, both Fourier transform infrared and X‐ray photoelectron spectroscopy spectra of the residual chars from the PVA/MP composites demonstrated that the catalytic effect of MP on the dehydration and decarboxylation reactions of PVA, and the chemical reactivity of MP during the chars‐forming reactions could be used to account for the changed thermal stability and flame retardancy of the PVA/MP composites. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
195.
Injectable hydrogels have attracted a lot of attention in drug delivery, however, their capacity to deliver water-insoluble or hydrophobic anti-cancer drugs is limited. Here, we developed injectable graphene oxide/graphene composite supramolecular hydrogels to deliver anti-cancer drugs. Pluronic F-127 was used to stabilize graphene oxide (GO) and reduced graphene oxide (RGO) in solution, which was mixed with α-cyclodextrin (α-CD) solution to form hydrogels. Native hydrogel was used as control. GO or RGO slightly shortened gelation time. The storage and loss moduli of the hydrogels were tracked by dynamic force measurement. The storage modulus of GO or RGO composite hydrogels was larger than that of the native hydrogel. Hydrogels were unstable in solution and eroded gradually. GO or RGO in Pluronic F-127 solution could potentially improve the solubility of the water-insoluble anti-cancer drug camptothecin (CPT), especially with large drug-loaded CPT amount. Drug release behaviors from solutions and hydrogels were characterized. The nanocomponents (GO or RGO) were able to bind more drug molecules either for CPT or for doxorubicin hydrochloride (DXR) in solution. Therefore, GO or RGO composite hydrogel could potentially enable better controlled and gentler drug release (for both CPT and DXR) than native hydrogel. 相似文献
196.
Abstract This paper reports a new polymer flooding agent used for enhanced oil recovery (EOR), poly(acrylamide-acrylic acid) [P(AM-AA)]/poly(acrylamide-dimethyldiallylammonium chloride) [P(AM-DMDAAC)] polyelectrolyte complex. The solution viscosity of prepared P(AM-AA)/P(AM-DMDAAC) complex is enhanced due to the strong interaction between the two oppositely charged copolymers, i.e., P(AM-AA) and P(AM-DMDAAC), which were prepared through radical copolymerization. The ionic content could be controlled by changing the reaction conditions. The structures of the two copolymers were characterized through FT-IR, 1H NMR, and acidic and precipitation titration. The formation as well as the factors affecting the P(AM-AA)/P(AM-DMDAAC) polyelectrolyte complex were investigated by means of viscosity measuring and light transmittance testing. The experimental results show that the composition of the copolymers, the pH value, and the concentration of the polymer solutions have remarkable effects on the formation of P(AM-AA)/P(AM-DMDAAC) polyelectrolyte complex and the solution viscosity. When DMDAAC content in P(AM-DMDAAC) is 3.2 mol%, AA content in P(AM-AA) is 48–58 mol%, the weight ratio of P(AM-AA) to P(AM-DMDAAC) is 70/30–30/70, the pH value of the solution is 6–10, and the concentration of solution is 1000–3500 ppm, then a homogeneous solution of P(AM-AA)/P(AM-DMDAAC) poly-electrolyte complex could be obtained which exhibits a much higher solution viscosity compared with its components. 相似文献
197.
Israel Zilbermann Avraham Meshulam Haim Cohen Dan Meyerstein 《Supramolecular chemistry》2013,25(2):325-332
Abstract The mechanisms and kinetics of oxidation of ascorbate, AH?, by Ni(III)Li aq and by LiNi(III) (HPO4)2 ? complexes (L1 = meso-(5,12)-7,7,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; L2 = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) in neutral aqueous solutions have been investigated. The oxidation of ascorbate by the LiNi(III) (HPO4)2 ? and Ni(III)L1 aq proceeds via two consecutive reactions well separated in time. The products of the first reaction are the A.? radical anion and the corresponding Ni(II) complex. The oxidations by the LiNi(III)(HPO4)2 ? complexes proceed via the outer sphere mechanism, whereas the detailed mechanism of reaction of Ni(III)L1 aq cannot be determined. The rate of reaction decreases with the increase in the concentration of phosphate, thus indicating that LiNi(III)(HPO4)(H2O)+ and LiNi(III)OH2+ are stronger oxidizing agents than LiNi(III)(HPO4)? 2. The oxidation of ascorbate by Ni(III)L2 aq proceeds via three consecutive reactions which are well separated in time. Thus the results clearly point out that this process occurs via the inner sphere mechanism. The first transient observed is tentatively identified as L2(H2O)Ni(II)(A.?)2+, i.e., an unexpected complex of the ascorbate anion radical. Also in this process the last transient observed is the A.? anion radical. The stabilization of the ascorbyl radical in a transient complex might be of biological significance. 相似文献
198.
Ying Su Christos S. Karamitros Julian Nomme Theresa McSorley Manfred Konrad Arnon Lavie 《Chemistry & biology》2013,20(4):533-540
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199.
Binbin Wei Qing Li Ronghua Fan Dan Su Xiuli Ou Kelin Chen Xiaohui Chen Ying Jia Kaishun Bi 《Journal of mass spectrometry : JMS》2013,48(4):448-458
Schisandra chinensis (Turcz.) Baill., a traditional Chinese medicine, has been clinically used for the treatment of insomnia for centuries. The insomnia mechanism and the possible active ingredients of S. chinensis remain largely unknown. The objective of this study was to develop a method to detect its components which could pass through the blood brain barrier (BBB) by determining the brain microdialysate and brain tissue homogenate samples and then obtain the pharmacokinetic profile in brain for comprehensive understanding of its hypnotic clinical efficacy. Therefore, an efficient, sensitive and selective ultra fast liquid chromatography/tandem mass spectrometry method for the simultaneous determination of six sedative and hypnotic lignans (schisandrin, schisandrol B, schisantherin A, deoxyshisandrin, γ‐schisandrin and gomisin N) of Schisandra chinensis (Turcz.) Baill. in rat brain tissue homogenate and brain microdialysates has been developed and validated. The analysis was performed on a Shim‐pack XR‐ODS column (75 mm × 3.0 mm, 2.2 µm) using gradient elution with the mobile phase consisting of acetonitrile and 0.1% formic acid water. The method was validated in brain homogenate and microdialysate samples, which all showed good linearity over a wide concentration range (r2 > 0.99), and the obtained lower limit of quantification was 0.1 ng · ml?1 for the analytes in brain microdialysate samples. The intra‐ and inter‐day assay variability was less than 15% for all analytes. The study proved the six lignans, as sedative and hypnotic ingredients, could pass through the BBB with brain targeting, distributed mainly in the hypothalamus and possessed complete pharmacokinetics process in brain. The results also indicated that significant difference in pharmacokinetic parameters of the analytes was observed between two groups, while absorptions of these analytes in insomniac group were significantly better than those in normal group. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
200.
Yuqiao Wang Huijun Zhang Dan Yao Junjie Pu Yuan Zhang Xiaorui Gao Yueming Sun 《Journal of Solid State Electrochemistry》2013,17(3):881-887
Graphene/Fe3O4 nanocomposite was prepared for the immobilization of hemoglobin (Hb) to improve the electron transfer between Hb and glass carbon electrode (GCE). The characterization of nanocomposites was described by transmission electron microscopy, Fourier transform infrared, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The electrochemistry of Hb on the graphene/Fe3O4-based GCE was investigated by cyclic voltammetry and amperometric measurement. The modified electrode showed a wide linear range from 0.25 μmol/L to 1.7 mmol/L with a correlation coefficient of 0.9967. The detection limit of the H2O2 biosensor was estimated at 6.0?×?10?6?mol/L at a signal-to-noise ratio of 3. 相似文献