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81.
讨论一种微波、毫米波电磁材料特性和参数宽频带测量方法——自由空间法。给出了该测量方法的测试原理和基于国产AV3630幅相接收机为基础的测试系统构成及系统扩频方法,论述了自由空间测试法需注意的关键技术问题。  相似文献   
82.
运用过程分析式清洁生产审计开展清洁生产,通过对工艺过程、作业活动的过程分析,充分查找物料流失环节及废弃物的排放点.不需过多的经济投入解决物料计量问题,不需用物料衡算方法,而且查找细致、全面、有效且易于操作,不易遗漏,更有利于企业的清洁生产。  相似文献   
83.
城市生活垃圾综合处理系统的选择   总被引:15,自引:0,他引:15  
以上海城市生活垃圾处置为对象,利用层次分析方法,选择了分选回收+堆肥+卫生填埋的综合处置系统,并且确定了堆肥方式应首先考虑仓式静态好氧堆肥。经过运行费比较,所选择的综合处置系统比现行的处置系统具有明显的优势。  相似文献   
84.
输油管道的泥土封堵与蒸汽置换动火技术   总被引:3,自引:0,他引:3  
介绍了输油管道检修中的泥土封堵动火与蒸汽置换动火技术方法。详细阐述了应用泥土封堵更换一段管道动火、管道改流程并在天窗两边加盲板动火、更换污水管线弯头动火、应用蒸汽置换更换一段管道动火和管道改流程动火的实施例。在实际应用中,可根据动火检修管道的具体情况,选用其中的一种或两种方法并用。  相似文献   
85.
Variability in the level of expression of very long chain fatty acids (VLCFAs) is documented in cultured chorionic villus (CV) cells derived from two fetuses, one at risk for an unusual peroxisomal fatty acid β-oxidation defect, and the other at risk for the X-linked form of adrenoleucodystrophy (ALD). Cells from early subcultures of chorionic cells from both cases gave normal values for VLCFA ratios. The results for the fetus at risk for the β-oxidation defect were interpreted to indicate that the fetus was not affected; however, at birth, the infant was clinically and biochemically affected. In the case of the fetus at risk for X-linked ALD, although VLCFAs were normal in subculture 1, the levels of these fatty acids increased dramatically in subculture 3, suggesting an abnormal fetus. Termination of the pregnancy and subsequent biochemical and morphological follow-up confirmed that the fetus was indeed affected by ALD.  相似文献   
86.
A new approach applying fuzzy mathematic theorems, including the Primary Matrix Element Theorem and the Fisher Classification Method, was established to solve the optimization problem of atmospheric environmental sampling sites. According to its basis, an application in the optimization of sampling sites in the atmospheric environmental monitoring was discussed. The method was proven to be suitable and effective. The results were admitted and applied by the Environmental Protection Bureau (EPB) of many cities of China. A set of computer software of this approach was also comuletelv comniled and used.  相似文献   
87.
饮用水中五种有机磷农药的快速检测法   总被引:6,自引:0,他引:6  
本文介绍了使用Waters OASIS-HLB固相萃取小柱从水中分离富集敌百虫、敌敌畏、乐果、甲基对硫磷,对硫磷五种有机磷农药的快速检测法。  相似文献   
88.
The aim of the study was to describe the opinion of pregnant women who had accepted or declined an alpha-fetoprotein (AFP) test, not only on AFP screening in general, but also on whether every pregnant woman should be offered amniocentesis (AC)/chorionic villus sampling (CVS) and an ultrasound scan for fetal malformations. An additional aim was to describe pregnant women's attitudes concerning continued research in the prenatal field. The study was performed as a questionnaire study in two regions over a 1-year period from 1 October 1988 to 30 September 1989. Results are based on answers from 3331 women who had taken an AFP test and 336 women who had declined the offer of a test. A total of 79 per cent of the women thought that an AFP test, 70 per cent that an ultrasound scan for fetal malformations, and 26 per cent that AC or CVS should be offered to all pregnant women. Fifty-nine per cent of the women were positive towards continued research in the prenatal field. Women who had had an AFP test were generally much more positive towards screening and research than women who had declined, who were generally against. Women who had left school without a high school degree were on average more positive towards the screening issues than women who had this degree. In conclusion, the results obtained in this study strongly suggest that women's attitudes are very dependent on how the prenatal screening programme is already organized in their local area.  相似文献   
89.
Maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (βhCG) measurements taken prior to chorionic villus sampling (CVS) in 21 patients who subsequently miscarried were compared with measurements in a control group of 113 patients with uneventful pregnancies. Patients with AFP levels of 10 iu/ml or more prior to the CVS had a 4·3 times greater risk of miscarriage (95 per cent confidence interval 1·3–13·6). AFP levels obtained 1 week after the CVS in the 13 patients with late miscarriages were higher than in the control group (P = 0·06). Patients miscarrying had a greater rise in AFP (P = 0·06) and a greater fall in βhCG levels (P = 0·04) following the CVS procedure, compared with the control subjects. Each 10-unit change in the difference between AFP or βhCG levels prior to and 1 week following the CVS was associated with a significantly increased risk for late miscarriage. Elevated maternal serum AFP levels early in pregnancy and changes in AFP and βhCG levels following CVS may predict an increased risk for subsequent miscarriage.  相似文献   
90.
We have devised and evaluated a rapid screening method for the detection of numerical aberrations of chromosomes13, 18 and 21 in chorionic villus cells. We used non-radioactive in situ hybridization (ISH) with three chromosome-specific probes on overnight-attached mesenchymal cells from chorionic villi. A blind study was performed of 47 karyotypically normal samples, one triploid sample, two samples trisomic for chromosome 21, and two samples from a fetus with putative mosaicism (46/47, +21). All samples were hybridized with the chromosome 18- and 21-specific probes. Thirty samples were additionally hybridized with the chromosome 13-specific probe. The test could be completed within 3-4 days of sampling. In samples disomic with respect to the probed chromosomes, an average of 2 per cent (range 0-9 per cent) had three hybridization signals. By contrast, in the samples trisomic for the probed chromosome(s), 57 per cent (chromosome 13), 51 per cent (chromosome 18), and an average of 74 per cent (55-86 per cent) (chromosome 21) of the nuclei exhibited three signals. In the putative mosaic samples, the number of nuclei with three chromosome 21-specific signals ranged from 41 to 69 per cent. We conclude that this technique rapidly and clearly distinguishes between normal and trisomic/triploid samples, and consequently may be of use in future prenatal diagnosis.  相似文献   
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