首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
A method is described for the specific hydrolysis of amino acids from humic substances by using the proteolytic enzyme “Pronase E”. The amino acids are analyzed by a fluorescence detector after precolumn derivatization and HPLC-separation. The pattern and the concentration of amino acids after the enzymatic hydrolysis are set up for humic substances of different origin. Due to the results the enzymatic hydrolysis is suitable for the characterization of humic substances with a nitrogen content higher than 3%. As shown in a kinetic study of the hydrolysis of a fulvic acid the influence of humic substances on the enzyme activity increases in case of lower nitrogen content. Due to the specificity of the proteolytic enzyme the operationally defined method is limited as shown by a protein of a known amino acid content. The amino acids leucine, valine, tyrosine and histidine are released to the highest extent. The determined total extent for the hydrolysis of Insulin B is 26.34% and for Casein 38.37%. By comparison of the enzymatic hydrolysis with the classic acid hydrolysis the advantages of the biochemical method are the simple experimental handling and the mild reaction conditions. Amino acids which are very unstable like glutamine and asparagine can only be analyzed by the enzymatic hydrolysis.  相似文献   

4.
5.
6.
For the shallow lake there can be expected eutrophic conditions according to its morphometric data (z? 2.8 m, l 1.1… 1.8a), even mesotrophic conditions acc. to the catchment area (2.8 km2/hm3, 8 km2/km2, 20% wood) and eutrophic conditions acc. to load (1,340 Population Equivalents/hm3, 0.027… 0.386 g/m2 a P). The actually measured data of oxygen balance, nutrient contents and bioproduction show a eutrophic situation with a trend towards polytrophy. The difference to the expectation values can be explained by an underestimation of direct loading from a duck farm and the back-wash waters of a waterworks, so that sanitation measures for reducing the direct loading are promising. The relocation of the duck farm and of a large complex of stables as well as the introduction of extensive fishery utilization with a balanced stock of predatory fish resulted in perceptible trends of oligotrophication already after two years, especially by a remarkable promotion of the macrophyte stocks in the shallow water zone.  相似文献   

7.
8.
9.
10.
11.
12.
Using of a New Field Analysis Method to Investigate the Stability of Arsenic and its Inorganic Species in Aquatic Systems The stability of arsenic species in aquatic systems is limited by the possibilities of chemical and biochemical reactions. Redox reactions and bioalkylation lead to changes of the species ratios. In this work, the stability of As(III) and As(V) was examined at storage of distilled, de-ionized, and drinking water at different conditions (refrigerator/room temperature; daylight/darkness) and additions (sulfuric acid; ascorbic acid). The determination of these species was carried out by a modified spectrophotometric method, suitable for laboratory analysis as well as for field analysis. The results show that chemical oxidation and biochemical reduction can occur. Sulfuric acid is favourable for the stabilization of total arsenic and of the inorganic species.  相似文献   

13.
Zusammenfassung Eine statistische Analyse der geophysikalischen Potentialfelder, die durch Intensität und Frequenz der regionalen Anomalien bestimmt werden, liefert interessante Ergebnisse über die Struktur der Erdkruste. Im einzelnen können die Tiefe von horizontalen Diskontinuitäten, die Lage von vertikalen tektonischen Störungen, tektonische Vorzugsrichtungen als mittlere Richtungen der Anomalientrends und die mittlere Tiefe derCurie-Isotherme bestimmt werden. Die Grundlage der statistischen Untersuchungen stellt die Korrelationsanalyse dar. Die verschiedenen Methoden werden im einzelnen beschrieben.
Summary A statistical analysis of the geophysical potential fields, which are characterized by intensity and frequency ofthe regional anomalies, shows interesting results on the structure of the crust. Especially there may be determined the depth of horizontal discontinuities, tectonicmean directions as mean directions of anomaly trends and the mean depth of theCurie-point. The basis of the statistical investigations is the correlation-analysis. The several treatments are described in detail.


Mitteilung aus dem Geomagnetischen Institut der DAW, Potsdam, Nr. 264.  相似文献   

14.
So far, the MPN technique has been the method chosen for detecting pathogenic bacteria in waters, since it allows us to use larger volumes. In the evaluation, however, comparatively frequently (10 … 15%) nontypical codes occur. The validity of the Poisson model is confirmed for pure cultures by extensive laboratory experiments with pure cultures and controlled mixed cultures. In mixed cultures, however, a comparatively large number of atypical codes occur, since obviously a single organism is not sufficient for the formation of a growth-cover on the test tube, so that the true number of germs may be considerably underestimated. Obviously, the accompanying flora has an inhibiting effect on the salmonella detection.  相似文献   

15.
By a comparison of methods of the nitrate determination in groundwater the correctness of the values of more than 10 mg/1 nitrate determined with a Nitratsensitrode (VEB Kombinat Keramische Werke Hermsdorf) is proved. In this range of concentrations, the rate of retrieval and the coefficient of variation are about 99.6 % and 2.5 %, respectively. Measured values from samples with less than 10 mg/1 nitrate have a larger error and are recorded as too high.  相似文献   

16.
17.
A gas-sensitive electrode for the determination of ammonia was tested on the basis of potentiometry by means of parts of measuring devices from the CMEA region. Samples of water, cattle slurry, pig slurry and silo seepage water in the range of concentrations of 10?5 … 10?1 mol/1 NH4-N can be measured. Before measurement the samples have to get pH 11 and have to be diluted, if necessary. A maximum period of time of about eight minutes is required for attaining the potential constancy. The relative standard deviation varies between 0.1 and 4.79%; the rate of retrieval was 99.1% on an average. The results of the potentiometric measurements were equivalent to those of the acidimetric measuring method. The practical advantages consist in a low expenditure of material, energy and time.  相似文献   

18.
The analytical measurement technique presented consists of the ADM 300 flow stream system with two-channel operation and the AE 4 evaluation unit for four-channel operation. Selected parameters for important components of water quality are presented, such as those used in preferred combined methods in the practice of the laboratories of water and wastewater monitoring. The following components with detection limits in mg/l are concerned: ammonium 0.04, nitrite 0.07, nitrate 0.32, Norg. 0.35, o-PO4 0.02, total PO4 0.08, SiO2 0.08, sum of cations 0.79 mmole/l; Mn 0.02, Fe 0.34, Cl? 15.4 and UV-absorbance 0.01 cm?1. The detailed examination of the techniques on samples of waters has proved a statistically secured agreement of the analytical results with the results of the standard methods, with the simultaneous increase of the number of analyses by 100 … 300= and a saving of chemicals of 80= compared with the manual analysis. The device system has the interfaces required for the further data processing by means of PC. The boundary conditions for the application of this technique, especially the necessary lot sizes and laboratory organization, are referred to.  相似文献   

19.
Zusammenfassung In den letzten Jahren wurden in den Erzgruben des Siegerlandes reflexionsseismische Messungen untertage ausgeführt. Für die Auswertung der hierbei erhaltenen Seismogramme sind besondere Verfahren erforderlich, die in der vorliegenden Arbeit entwickelt werden.Im ersten Teil werden die auftretenden geometrischen Probleme behandelt. Es wird gezeigt, daß man bei der Auswertung von Untertage-Seismogrammen zweckmäßigerweise jeden Reflexionseinsatz einzeln auswertet. Man erhält auf diese Weise eine Schar von Ellipsen, deren Häufungszone die Lage der reflektierenden Fläche erkennen lässt. Eine Möglickeit zur Berücksichtigung des Einfallwinkels wird durch geometrische Betrachtungen gefunden.Im zweiten Teil wird die Lage der Reflexionsebene durch rechnerische Methoden festgelegt. Zunächst wird dargelegt, daß hierzu die Korrelationsrechnung angewandt werden kann. Es ergeben sich jedoch einige Nachteile bei der praktischen Anwendung des Verfahrens.So wird die Aufgabe schließlich mit Hilfe der Fehlerrechnung gelöst. Hier kommt es darauf an, durch geeignete Näherungsformeln den Arbeitsaufwand auf ein erträgliches Maß zu bringen. Das erhaltene Ergebnis führt zu einer Festlegung von Lage und Streichrichtung der reflektierenden Fläche und liefert dabei eine Angabe über die Genauigkeit des erzielten Resultates. Schließlich wird angedeutet, wie man das statistische Verhalten der einzelnen Meßwerte untersuchen kann.
Summary During the last years reflection-seismic measurements have been carried out in the ore mines of Siegerland. The special methods required for the interpretation of the seismograms obtained in this work are developed in the present paper.The first part deals with geometric problems arising. It is shown that in the interpretation of subsurface-seismograms each reflection event purposely is to be treated individually. In this way a family of ellipsoids is obtained whose zone of aggregation allows to recognize the position of the reflecting surface. A possibility of taking into account the angle of dip is found by geometrical considerations.In the second part the position of the reflecting surface is ascertained by arithmetical methods. At first, it is shown that correlation arithmetic may be adopted to this purpose. In employing this method practically some disadvantage will, however, be involved.Finally, for the solution of the problem the law of least squares is adopted. In doing so the question arises how to reduce the bulk of work to a reasonable amount by means of approximation formulas. The results thus obtained make it possible to determine the position and strike of the reflecting surface and yield data concerning the accuracy of the results obtained. Then, it is indicated how the statistical behaviour of the individual measurements can be analyzed.


Gekürzte Fassung einer Dissertation, Bergakademie Clausthal 1954 (Berichterstatter Professor Dr.Karl Jung).  相似文献   

20.
From polychlorinated paraffins (C = 13 … 19) cation-active products are obtained on a bench scale by conversion with ethylenediamine and subsequent quaternization with dimethyl sulphate. The cation-active products are investigated with respect to their efficiency in the coagulating flotation of wastewaters of the petroleum industry. The content of petroleum-containing products, the value of COD-Cr as well as turbidity and colouration are reduced by up to 90, 67 and 86%, respectively. These results are almost equivalent to those of a commercial flocculant, which was used by comparison, and considerably exceed the results of FeSO4.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号