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61.
The problem of the presence of carcinogens in the environment has become of considerable concern to the public, as it has been to the biomedical community for some time. The burden of identifying carcinogenic agents and determining threshold levels, if they exist, falls upon the scientific community. Particular care must be exercised in the design, conduct and analysis of experiments directed toward the identification of carcinogens. The data generated from such tests provides the basis for regulatory decisions by governmental authorities. The advice provided by scientists must be based on sound data. There have been instances, however, and there will be others, in which biological variability and the limits of sensitivity of our tests will give equivocal results. It is the duty of scientists to bring such uncertainties to the attention of the public while working towards the development of more sensitive and precise techniques.  相似文献   
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本文对采用过二硫酸铵 (NH4) 2 S2 O8法从 Li Mn2 O4中萃取锂离子进行了研究 ,并就所获得吸附剂 (Mn O2 (Li) )的特性 ,特别是对于分离锂同位素的能力进行了测试。在良好的控制条件下 ,(NH4) 2 S2 O8是一种优良的锂吸附剂 ,它具有非常高的锂萃取度 ,同时保持锰的最小溶解性。所制备的 Mn O2 (Li)在 2 5°C时最大的 7Li/ 6Li同位素分离因子为 1 .0 1 4,它是那些商品有机离子交换剂的几倍。  相似文献   
64.
Errors in pointing to actual and remembered targets presented in three-dimensional (3D) space in a dark room were studied under various conditions of visual feedback. During their movements, subjects either had no vision of their arms or of the target, vision of the target but not of their arms, vision of a light-emitting diode (LED) on their moving index fingertip but not of the target, or vision of an LED on their moving index fingertip and of the target. Errors depended critically upon feedback condition. 3D errors were largest for movements to remembered targets without visual feedback, diminished with vision of the moving fingertip, and diminished further with vision of the target and vision of the finger and the target. Moreover, the different conditions differentially influenced the radial distance, azimuth, and elevation errors, indicating that subjects control motion along all three axes relatively independently. The pattern of errors suggest that the neural systems that mediate processing of actual versus remembered targets may have different capacities for integrating visual and proprioceptive information in order to program spatially directed arm movements.  相似文献   
65.
beta, beta-Dichlorodiethylamine is proved not to induce structural disturbances in phosphatidylcholine liposomes and erythrocyte membranes which is registered by fluorescence methods. Methyl-beta, beta-dichlorodiethylamine and metaxylyl-beta, beta-dichlorodiethylamine cause the increase in microviscosity of lipid bilayer hydrophobic areas in both erythrocyte membranes and liposomes. Besides, polarity of the latter also decreases, and the metaxylyl derivative alkylates nucleophilic centers of phospholipid phosphate groups in liposomes. Erythrocyte membranes, being treated by beta, beta-dichlorodiethylamine derivatives, the increase in the membrane protein hydrophobicity is registered as well as the decrease in their immersion in the lipid bilayer.  相似文献   
66.
Gloves should provide two-way protection from the transmission of microorganisms between worker and patient. Until recently, glove manufacturers paid little attention to barrier properties. Because the operating room is a high-risk area, surgical nurses must be especially careful about gloving practices.  相似文献   
67.
The article presents results of clinical trial of finlepsine-retard. Objectivized parameters characterizing the time course of psychopathologic symptoms were studied in certain concentrations of finlepsine and beta-endrofin in blood serum. Atypical maniac states do not easily respond to therapies but finlepsine-retard gives the modern psychopharmacotherapy a new horizon.  相似文献   
68.
The authors present basic science for, elaborate and set as methodic recommendations some potentiometric methods using ion-selective electrodes. Efficiency of those methods was proved in experiments with such substances as boron compounds, hydrogen cyanide, hydrogen chloride. High sensitivity, selectivity, accuracy and rapidity of the methods with handy technique make the facilities available for analysis of air at workplace, ambient atmosphere, water and biologic materials, detecting wide range of concentrations. Practical application of the methods enabled to specify measures to preserve health of workers and general population, helped in hygienic evaluation of work conditions in composition materials production, high-temperature soldering, optic glass industry.  相似文献   
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Tumour ploidy is of prognostic value in colorectal cancer, DNA aneuploid tumours having a worse outlook. Nearly all studies have concentrated on the DNA content of the primary tumour. We have examined the ploidy of the primary tumour and its lymph node metastases in 71 cases of Dukes' stage C disease, to see whether this provides greater prognostic information than the primary alone. Analysis was performed using formalin-fixed, paraffin-embedded tumour sections. Ploidy of primary and metastases was different in 20 cases (28%), aneuploid nodes being seen with diploid primaries and vice versa. Ploidy of both the primary (chi 2 = 4.86, P = 0.03) and secondary (chi 2 = 4.86, P = 0.03) tumours predicted survival in univariate analysis. Combining the ploidy of primary and nodes, three prognostic groups could be defined--diploid primaries with diploid metastases (hazard relative to both aneuploid, 0.36) had significantly better survival than cases where the ploidy of the primary and nodes were mixed (relative hazard 0.47-0.56), which did better than cases with aneuploid primary and nodes. This study demonstrates that ploidy variation between primary and secondary tumours is common, and better prognostic information may be gained by studying both.  相似文献   
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