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排序方式: 共有203条查询结果,搜索用时 31 毫秒
1.
常规PID控制具有结构简单、稳定性好、可靠性高等优点,在调速系统中被广泛应用。但常规PID控制的设计需依靠数学模型,负载、模型参数的变化及非线性因素等影响常规PID的精确调节。单神经元PSD控制器利用神经元的自学习、自组织能力,根据被控对象的变化情况对控制器的权值进行在线调整,达到在线调整PID参数的目的,并且采用无需对象模型的控制算法构成了自适应控制。与常规的PID调节器相比,具有更好的鲁棒性。同时,通过对PSD控制器的改进,在直流伺服系统的仿真应用中得到了较理想的结果。  相似文献   
2.
目的:评价泰勒宁片和科洛曲片对隆乳手术后疼痛的疗效和不良反应。方法:采用随机开放平行对照试验。共完成60例,其中A组30例予泰勒宁片,单次1片;B组30例予科洛曲片,单次1片。结果:泰勒宁片对隆乳手术后引起的中度或重度疼痛总有效率可达96.7%,科洛曲片的总有效率可达83.3%。服药后泰勒宁片组的疼痛强度差均高于科洛曲组,经统计学处理,有显著性差异(P<0.05)。不良反应发生率较科洛曲片组高。结论:泰勒宁片为中强度镇痛药,对于隆乳手术后引起的中重度疼痛有良好的镇痛效果。  相似文献   
3.
讨论了强酸、强碱中和过程PH控制方案。以0.9mol/L的NaoH中和0.9mol/L的HNO3,流量增量为0.1-0.3kg/min,用模糊控制将PH控制在各要求的值上,ΔpH≤0.2,获得满意的结果。  相似文献   
4.
光离子化检测仪进行挥发性有机物测定研究   总被引:3,自引:0,他引:3  
陈兵 《实用预防医学》2006,13(2):447-448
目的在光离子化TVOC仪上,许多有机物都有浓度响应。采用现场直读仪器方法对空气中挥发性有机物进行测定,建立其方法。方法采用现场读数仪器和气体采样器同时在现场采样和测定,将现场采集的样品进行气相色谱分析,比较两种结果的差异。结果现场光离子化TVOC仪与气相色谱仪的测定结果无显著性差异。结论光离子化检测法适合室内空气中总有机挥发物的测定与国标法无差别。  相似文献   
5.
Serum and intracytoplasmic cytokines are mandatory in host defense against microbes, but also play a pivotal role in the pathogenesis of autoimmune diseases by initiating and perpetuating various cellular and humoral autoimmune processes.  相似文献   
6.
7.
《Vaccine》2015,33(30):3463-3470
BackgroundA vaccine against serogroup B Neisseria meningitidis, major cause of bacterial meningitis in children and adults, has recently been developed. In a context of an increasing parental mistrust against vaccinations, understanding the reason for their choices is crucial in order to improve immunization coverage. Our study aimed at evaluating parental attitudes and perceptions towards serogroup B meningococcal invasive disease vaccination.MethodsA prospective observational study was conducted in different French independent-practice medical offices (general practitioners and paediatricians) and nurseries between May 1 and December 31, 2013, using a questionnaire distributed in electronic and paper forms to parents having at least one child between the ages of 2 months and 16 years old.Results1270 parents were included, of whom 671 (52.8%) spontaneously stated to be in favour of this vaccination. Their choice was mainly justified by the severity of the disease (63.8%) and the desire to protect their child (51.7%). In multivariate analysis, the young age of parents (OR 0.949 per additional year; p < 10−3), the history of vaccination against serogroup C meningococcal invasive diseases (OR 6.755; p < 10−3), and the prior knowledge of the vaccine (OR 2.081; p = 0.001) were associated with vaccination acceptance. The main reasons for refusal were the lack of hindsight on this new vaccine (50.6%) and the fear of side effects (45.5%). After objective information on the disease and the vaccine, only 6.3% of the entire responding population would refuse to consider vaccination.ConclusionsThe spontaneous acceptance rate of vaccination against serogroup B meningococcal invasive disease is insufficient. However, after objective information by their physician or public health authorities, only a few parents would in the end be completely resistant.  相似文献   
8.
Epidemiological data exist to support a positive association between Chlamydia trachomatis (Ctr) infection and gynecological cancers; however, putative cellular mechanisms for this association are lacking. Here, we identified Ctr-induced perturbations to host cell phenotypes in vitro that persisted after clearance of infection and could directly contribute to host cell transformation. In particular, human telomerase catalytic subunit (hTERT) mRNA expression and catalytic subunit activity were increased in acute infected late passage IMR90E1A cells. hTERT upregulation was accompanied by recruitment of ceramide, a known regulator of hTERT, to the chlamydial inclusion and was abrogated following doxycycline-mediated infection clearance. In cells cleared of Ctr infection, average telomere length was slightly increased and immunofluorescence staining of the DNA damage marker γH2A.X was reduced after clearance of infection compared with cells that had not been infected. Reduced p53 binding to the promoter of the cell cycle checkpoint regulator p21 was also detected in cells cleared of infection and p21 levels were reduced; moreover, this cell population exhibited increased resistance to etoposide-induced DNA damage. Thus, Ctr infection altered cell aging and survival pathways, which persisted after infection clearance. Cells that survive infection are likely to exhibit altered physiology, as evidenced by an increased resistance to DNA damage-induced apoptosis, which may support cellular transformation.  相似文献   
9.
The objective of this present study was to evaluate the performance of a portable gas chromatograph-photoionization detector (GC-PID), under various test conditions to determine if it could be used in occupational settings. A mixture of 7 volatile organic compounds (VOCs)—acetone, ethylbenzene, methyl isobutyl ketone, toluene, m-xylene, p-xylene, and o-xylene—was selected because its components are commonly present in paint manufacturing industries. A full-factorial combination of 4 concentration levels (exposure scenarios) of VOC mixtures, 3 different temperatures (25°C, 30°C, and 35°C), and 3 relative humidities (RHs; 25%, 50%, and 75%) was conducted in a full-size controlled environmental chamber. Three repetitions were conducted for each test condition allowing for estimation of accuracy. Time-weighted average exposure data were collected using solid sorbent tubes (Anasorb 747, SKC Inc.) as the reference sampling medium. Calibration curves of Frog-4000 using the dry gases showed R2 > 0.99 for all analytes except for toluene (R2 = 0.97). Frog-4000 estimates within a test condition showed good consistency for the performance of repeated measurement. However, there was ~41–64% reduction in the analysis of polar acetone with 75% RH relative to collection at 25% RH. Although Frog-4000 results correlated well with solid sorbent tubes (r = 0.808–0.993, except for toluene) most of the combinations regardless of analyte did not meet the <25% accuracy criterion recommended by NIOSH. The effect of chromatographic co-elution can be seen with m, p-xylene when the results are compared to the sorbent tube sampling technique with GC-flame ionization detector. The results indicated an effect of humidity on the quantification of the polar compounds that might be attributed to the pre-concentrator placed in the selected GC-PID. Further investigation may resolve the humidity effect on sorbent trap with micro GC pre-concentrator when water vapor is present. Although this instrument does not fulfill the accuracy criterion specified in the NIOSH technical report No. 2012–162, it can be used as a screening tool for range finding monitoring with dry gases calibration in the occupational setting rather than compliance monitoring.  相似文献   
10.
The golden standard for functional evaluation of immunodeficiencies is the incorporation of [3H]-thymidine in a proliferation assay stimulated with mitogens. Recently developed whole blood proliferation assays have the advantage of parallel lymphocyte lineage analysis and in addition provide a non-radioactive alternative. Here we evaluate the Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA) in a comparison with [3H]-thymidine incorporation in four patients with severe combined immunodeficiency. The threshold for the minimum number of lymphocytes required for reliable responses in FASCIA is determined together with reference values from 100 healthy donors when stimulated with mitogens as well as antigen specific stimuli. Finally, responses against PWM and SEA + SEB stimuli are conducted with clinically relevant immunomodulatory compounds. We conclude that FASCIA is a rapid, stable and sensitive functional whole blood assay that requires small amounts of whole blood that can be used for reliable assessment of lymphocyte reactivity in patients.  相似文献   
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