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991.
Howden W.E. Wieand B. 《IEEE transactions on pattern analysis and machine intelligence》1994,20(6):445-462
Formal verification of program properties may be infeasible or impractical, and informal analysis may be sufficient. Informal analysis involves the informal acceptance, by inspection, of the validity of program properties or steps in an analysis. Informal analysis may also involve abstraction. Abstraction can be used to eliminate details and concentrate on more general properties. Abstraction will result in informal analysis if it includes the use of undefined properties. A systematic, informal method for analysis called QDA (Quick Defect Analysis) is described. QDA is a comments analysis process based on facts and hypotheses. Facts are used to create an abstract program model, and hypotheses are selected, nonobvious program properties which are identified as needing verification. Hypotheses are proved from the facts that define an abstraction. QDA is hypothesis-driven in the sense that only those parts of an abstraction that are needed to prove hypotheses are created. The QDA approach was applied to a previously well tested operational flight program (OFP). The QDA method and the results of the OFP experiment are presented. The problems of incomplete or unsound informal analysis are analyzed, the relationship of QDA to other analysis methods is discussed, and suggested improvements to the QDA method are described 相似文献
992.
The present study describes the development of an enzyme-linked immunosorbent assay capable of quantifying serum antibody of all four canine IgG subclasses. A panel of subclass-restricted and subclass-specific monoclonal antibodies was used to measure IgG subclasses in the serum of healthy dogs, as well as in dogs with a range of clinical diseases. The subclasses have been redefined as IgG1, IgG2, IgG3 and IgG4 based on a comparison with the relative concentration and electrophoretic mobilities of human IgG subclasses. In serum samples from healthy dogs, the concentration of IgG1 (mean, 8.17 +/- 0.95 mg ml-1) and IgG2 (mean, 8.15 +/- 3.16 mg ml-1) were very similar and considerably higher than the levels of IgG3 (mean, 0.36 +/- 0.43 mg ml-1) and IgG4 (mean, 0.95 +/- 0.45 mg ml-1). There was no apparent difference in the level of subclasses between the different breeds comprising this normal population. Sera from dogs with a range of immune-mediated or inflammatory diseases all had markedly elevated levels of IgG2 (more than 13 mg ml-1), but IgG1 decreased (less than 4 mg ml-1) to levels below the normal range. 相似文献
993.
Anmar W. Sabri Zainab H. Ali Serwan F. Shawkat Lamia A. Thejar Thaer I. Kassim Khalid A. Rasheed 《河流研究与利用》1993,8(3):237-250
The influences of the Samarra impoundment on the ecology of the downstream sector of the river Tigris are investigated. Zooplankton were collected monthly from July 1987 to July 1988. It was found that zooplankton were most abundant during high river discharges in March. During the month of low river discharge, September, the zooplankton population was greatly reduced immediately below the barrage and remained so to the last downstream station. Several factors seem to explain such differences. The high discharge from the impoundment was found to be the dominating factor and may flush the small backwaters in which zooplankton were abundant, thus increasing the population in the river. Zooplankton species vary in their ability to sustain populations in the river, variations which are due mainly to species-specific characteristics. 相似文献
994.
Investigations have been carried out on an erosion-corrosion apparatus to investigate the behaviour of corrosion-resistant highalloy iron-base materials containing hard phases. These materials had been optimized for increased wear resistance under complex stress conditions. As expected, in dry erosion tests, very low mass losses were established; there was little difference between the materials. Also, in corrosive environments (NaCl, H2SO4), the materials showed good stability; however, the duplex structures were superior to the martensitic ones. The combination of erosion and corrosion produced large differences and, in some cases, markedly reduced resistance to damage. These results confirmed observations that it is impossible to deduce the environmentally influenced mechanical behaviour of an alloy from its behaviour in separate corrosion and erosion experiments. The basic mechanisms underlying these processes have been investigated only tentatively. 相似文献
995.
Reflex sympathetic dystrophy, characterized by pain, swelling, vasomotor instability, and trophic changes in an extremity, has been infrequently described in patients with occult malignancy. Two cases of reflex sympathetic dystrophy associated with local tumor involvement are reported. Both patients had a history of cancer in clinical remission. Despite aggressive physical therapy measures, the patients' symptoms persisted. Workup of the first patient found an apical paravertebral mass in the lung; biopsy revealed recurrent breast carcinoma. In the second case, workup found an axillary mass contiguous with the lower brachial plexus. Biopsy revealed lymphoma, a second primary malignancy. In both cases, medical treatment of the tumor was instituted, with consequent improvement of hand and shoulder function. Both patients required prolonged hospitalization and multiple procedures that might have been avoided if malignancy had been suspected. Spontaneous development of reflex sympathetic dystrophy in patients with a history of cancer should alert the physician to the possibility of occult malignancy. 相似文献
996.
997.
N. M. Agh-Atabay W. Edward Lindsell Peter N. Preston Peter J. Tomb 《Polymer International》1993,31(4):367-374
Symmetrically substituted 1,3-diynes containing hydroxyalkyl ( 1a-d ), bromoalkyl ( 1e-h ) (diphenylphosphinyl) ( 1i-k ) and carboxyalkyl ( 2a-d ) substituents have been prepared and characterised; the phosphine derivative ( 1k ) has been converted with alkyl iodides ( RI ; R = Me, Et) into bis(phosphonium) salts ( 1l and m ). During preparation of the diynedioic acid. ( 2a ), the non-centrosymmetrical diyne, HO2CCH2C?C—C?C(CH2)2OH ( 3 ), was also isolated. 60Co γ-Irradiation of diacetylene monomers ( 2a – d ) and 10,12-tricosadiyn-1-oic acid gave the corresponding polydiacetylene derivatives ( 4a – d and 5 ), respectively. Rubidium salts of ( 4c ) and ( 4d ), a barium salt of ( 4c ), and a potassium salt of ( 5 ) were prepared and isolated; soluble potassium salts of the carboxylic acid polymers ( 4 ) were generated in aqueous solution. The effects of changes in pH on the UV/visible absorption spectra of aqueous solutions of selected carboxylic acid polydiacetylenes have been recorded, and are discussed. 相似文献
998.
Francis E. Powell Brian W. Brooks 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,57(1):65-71
Dimensionless material balance equations describing an uninhibited enzyme hydrolysis process in a semi-batch reactor (i.e. fed-batch reactor) are formulated; numerical solution of these equations provided concentration profiles of the enzyme-substrate complex by using published kinetic parameters. The unrestricted values obtained are compared with estimates based separately on the reaction steady state and stationary state assumptions. Results are discussed in terms of the enzyme/substrate inventory used and it is found that the reaction steady state is a satisfactory approximation only when this ratio is sufficiently small. The stationary state may be a better approximation at other values, particularly when enzyme is added to substrate or when an empty tank is being filled. Reaction yields from semi-batch and batch operations are compared. Processing takes longer in the semi-batch operations and complete conversions are only practical in this mode when enzyme is added to substrate. 相似文献
999.
A Ilnicka B Paw?owska J Czyzewska I G?ogowska J Korlak M Rodo K Bieganowska W Szirkowiec E Zdzienicka J Zaremba 《Canadian Metallurgical Quarterly》1996,30(1):65-75
The effects of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) and two Chinese traditional (Kampo) medicines, Dai-saiko-to and Saiko-ka-ryukotsu-borei-to on spontaneous soft tissue (heart and tongue) mineralization in DBA/2NCrj mice were studied. These agents were given orally for 4 weeks to DBA/2NCrj mice. After 2 weeks of administration in the heart, 0.006 and 0.03% (w/v) HEBP decreased calcium content by 90 and 30%, respectively, while 0.27 and 2.7 mg/ml Dai-saiko-to reduced calcium content by 30 and 45%, respectively. Saiko-ka-ryukotsu-borei-to (0.27 mg/ml) reduced both calcium and phosphorus content by 50 and 35%, respectively. However, their inhibitory effects on the heart were not observed after 4 weeks of administration. The compounds delayed the onset of increases of bulk calcium and phosphorus content. In the tongue, at 4 weeks, 0.006 and 0.03% (w/v) HEBP reduced calcium content by 30 and 45%, respectively, while two Kampo medicines (at both concentrations used) significantly reduced the content of calcium (by 27-79%) and phosphorus (by 24-32%). These results strongly suggest that two Kampo medicines as well as HEBP may be useful in preventing and curing soft tissue calcification. 相似文献
1000.