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双样条子域法分析变截面连续弯箱梁桥 被引量:4
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作者 徐光辉 丁汉山 《土木工程学报》 EI CSCD 北大核心 1990年第4期32-42,共11页
本文将规则外形但箱壁厚度有变化的弯箱梁桥划分为若干子域,每个子域上用乘积型样条函数逼近子域的位移状态,基于变分原理导得截锥壳基本子域的刚度矩阵,从而建立结构的总刚度方程。本文方法在处理截面厚度变化、内横隔板、不同荷载及... 本文将规则外形但箱壁厚度有变化的弯箱梁桥划分为若干子域,每个子域上用乘积型样条函数逼近子域的位移状态,基于变分原理导得截锥壳基本子域的刚度矩阵,从而建立结构的总刚度方程。本文方法在处理截面厚度变化、内横隔板、不同荷载及不同支承条件时几乎无需增加计算工作量。编制了适于微机应用的程序,计算结果得到模型试验的验证。说明对常用的单箱单室或单箱双室的连续弯箱梁桥,完全可用微机进行空间分析,并具有精度高、计算工作量少等特点。 展开更多
关键词 双样条子域法 弯箱梁桥 连续
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双样分析精密度的表示方法和评价 被引量:1
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作者 杨慧辉 周易 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 1994年第1期61-66,共6页
双样分析精密度有多种表达式。本文对标准偏差、平均偏差、极差及其应用范围作一简述。使用表达式R=A-B<2.48作为判据,可以简单和有效地确定常规分析中重复性精密度是否符合要求。
关键词 分析化学 双样分析 精密度 极差
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岩石土壤及沉积物样品中^(210)Pb-^(210)Bi-^(210)Po的快速联合测定 被引量:5
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作者 王玉学 郭冬发 +3 位作者 黄秋红 王哲 孙伟 刘立坤 《岩矿测试》 CAS CSCD 北大核心 2013年第3期462-468,共7页
铀系核素210Pb-210Bi-210Po目前通常采用相对独立的分析技术,三核素分别进行测定,并存在一些技术问题需要解决。文献报道的三核素联测技术需要使用多种昂贵的测试设备和示踪剂,或者制源体系抗干扰能力较弱且分析周期较长。本文研究了21... 铀系核素210Pb-210Bi-210Po目前通常采用相对独立的分析技术,三核素分别进行测定,并存在一些技术问题需要解决。文献报道的三核素联测技术需要使用多种昂贵的测试设备和示踪剂,或者制源体系抗干扰能力较弱且分析周期较长。本文研究了210Bi、210Po同时且定量恒温自沉积于铜箔的最佳制源条件,建立了双样-两次铜箔恒温自沉积制源-总α、总β同时计数法快速联合测定岩石、土壤及沉积物样品中210Pb-210Bi-210Po的分析技术。结果表明,当铜镀片面积为3.14 cm2,盐酸浓度为0.5 mol/L,氯化钠浓度为3.5 mol/L,溶液体积为20 mL,恒温90℃,振速为120 r/min,振幅20 mm,制源70 min,210Bi和210Po可同步定量自沉积且210Pb不沉积。在抗坏血酸存在下,大量共存元素不干扰自沉积。方法的精密度优于5%,全程加标放化回收率在99.5%~100.5%之间。该联测技术采用的制源体系抗稳定铋干扰能力较强,回收稳定,分析周期短,仅需一台国产测试设备并无需示踪剂即可完成三核素联合测定,同时也适合于三核素的独立测定。 展开更多
关键词 铜箔 210Pb 210Bi 210Po 双样 联合测定 总α总β计数
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Role of bisphosphonates in osteoporosis caused by adult growth hormone deficiency 被引量:1
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作者 CHENG Zhiling LI Jie +1 位作者 CHEN Zhongpei REN Wei 《中南大学学报(医学版)》 CAS CSCD 北大核心 2024年第6期839-847,共9页
In recent years,growth hormone and insulin-like growth factors have become key regulators of bone metabolism and remodeling,crucial for maintaining healthy bone mass throughout life.Studies have shown that adult growt... In recent years,growth hormone and insulin-like growth factors have become key regulators of bone metabolism and remodeling,crucial for maintaining healthy bone mass throughout life.Studies have shown that adult growth hormone deficiency leads to alterations in bone remodeling,significantly affecting bone microarchitecture and increasing fracture risk.Although recombinant human growth hormone replacement therapy can mitigate these adverse effects,improving bone density,and reduce fracture risk,its effectiveness in treating osteoporosis,especially in adults with established growth hormone deficiency,seems limited.Bisphosphonates inhibit bone resorption by targeting farnesyl pyrophosphate synthase in osteoclasts,and clinical trials have confirmed their efficacy in improving osteoporosis.Therefore,for adult growth hormone deficiency patients with osteoporosis,the use of bisphosphonates alongside growth hormone replacement therapy is recommended. 展开更多
关键词 growth hormone adult growth hormone deficiency OSTEOPOROSIS BISPHOSPHONATES insulin-like growth factor 1 SKELETON
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Megestrol acetate plus metformin for fertility-sparing treatment of atypical endometrial hyperplasia and early-stage endometrial adenocarcinoma: a prospective study
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作者 Yuanyuan WANG Tianjiao LAI +4 位作者 Danxia CHU Jing BAI Shuping YAN Haixia QIN Ruixia GUO 《南方医科大学学报》 CAS CSCD 北大核心 2024年第11期2055-2062,共8页
Objective To evaluate the efficacy of medroxyprogesterone acetate(MA)plus metformin as the primary fertility-sparing treatment for atypical endometrial hyperplasia(AEH)and early-stage grade 1 endometrial adenocarcinom... Objective To evaluate the efficacy of medroxyprogesterone acetate(MA)plus metformin as the primary fertility-sparing treatment for atypical endometrial hyperplasia(AEH)and early-stage grade 1 endometrial adenocarcinoma(G1 EAC)and the recurrence rate after treatment.Methods Sixty patients(aged 20-42 years)with AEH and/or grade 1 EAC limited to the endometrium were enrolled prospectively and randomized into two groups(n=30)to receive oral MA treatment at the daily dose of 160 mg(control)or MA plus oral metformin(850 mg,twice a day)for at least 6 months.The treatment could extend to 12 months until a complete response(CR)was achieved,and follow-up hysteroscopy and curettage were performed every 3 months.For all the patients who achieved CR,endometrial expressions of IGFBP-rP1,p-Akt and p-AMPK were detected immunohistochemically.Results A total of 58 patients completed the treatment.After 9 months of treatment,23(76.7%)patients in the combined treatment group and 20(71.4%)in the control group achieved CR;two patients in the control group achieved CR after converting to the combined treatment.The recurrence rate did not differ significantly between the control group and combined treatment group(30.0%vs 22.7%,P>0.05).Ten(35.7%)patients in the control group experienced significant weight gain of 5.7±6.1 kg,while none of the patients receiving the combined treatment exhibited significant body weight changes.Compared with the control group,the patients receiving the combined treatment showed enhanced endometrial expressions of IGFBP-rP1 and p-AMPK with lowered p-Akt expression.Conclusion Metformin combined with MA may provide an effective option for fertility-sparing treatment of AEH and grade 1 stage IA EAC,and the clinical benefits of metformin for controlling MA-induced weight gain and promoting endometrial expressions of IGFBP-rP1 and p-AMPK while inhibiting p-Akt expression warrants further study. 展开更多
关键词 endormetrial adenocarcinoma METFORMIN atypical endometrial hyperplasia fertility-sparing treatment megestrol acetate insulin-like growth factor binding protein-related protein 1
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Cloud-point extraction and preconcentration of bisphenol A from water samples 被引量:2
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作者 谭志坚 李芬芳 《Journal of Central South University》 SCIE EI CAS 2012年第8期2136-2141,共6页
A novel cloud-point extraction (CPE) was successfully used in preconcentration of biphenol A (BPA) from aqueous solutions. Majority of BPA is extracted into the surfactant-rich phase. The parameters affecting the ... A novel cloud-point extraction (CPE) was successfully used in preconcentration of biphenol A (BPA) from aqueous solutions. Majority of BPA is extracted into the surfactant-rich phase. The parameters affecting the CPE such as concentration of surfactant and electrolyte, equilibration temperature and time and pH of sample solution were investigated. The samples were analyzed by high-performance liquid chromatography with ultraviolet detection. Under the optimized conditions, preconcentration of 10 mL sample gives a preconcentration factor of 11. The limit of detection (LOD) and limit of quantification (LOQ) are 0.1 μg/L and 0.33 μg/L, respectively. The linear range of the proposed method is 0.2-20 μg/L with correlation coefficients greater than 0.998 7 and the spiking recove6es are 97.96%-100.42%. The interference factor was tested and the extraction mechanism was also investigated. Thus, the developed CPE has proven to be an efficient, green, rapid and inexpensive approach for extraction and preconcentration of BPA from water samples. 展开更多
关键词 biphenol A cloud-point extraction extraction mechanism high-performance liquid chromatography water samples
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