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21.
22.
Juniperus communis has been used e.g. as poles (posts), haysticks and wall-coating. In some districts it has even been an important export article. The fields of columnar juniper are the result of a long history of cultivation and grazing. In this article the main types of juniper fields in Sogn, Western Norway are presented, and their relationships to soil conditions and traditional use are discussed. According to structure, utilization and development four main types of juniper fields are recognized: I. Traditional juniper fields, II. Semi-cultural juniper fields, III. Secondary juniper fields and IV. Semi-natural juniper fields. Due to changes in agricultural methods, juniper fields are becoming rare. 相似文献
23.
P de Taxis du Po?t Y Arcand R Bernier J N Barbotin D Thomas 《Applied and environmental microbiology》1987,53(7):1548-1555
Stability of the plasmid pKK223-200 in Escherichia coli JM105 was studied for both free and immobilized cells during continuous culture. The relationship between plasmid copy number, xylanase activity, which was coded for by the plasmid, and growth rate and culture conditions involved complex interactions which determined the plasmid stability. Generally, the plasmid stability was enhanced in cultured immobilized cells compared with free-cell cultures. This stability was associated with modified plasmid copy number, depending on the media used. Hypotheses are presented concerning the different plasmid instability kinetics observed in free-cell cultures which involve the antagonistic effects of plasmid copy number and plasmid presence on the plasmid-bearing/plasmid-free cell growth rate ratio. Both diffusional limitation in carrageenan gel beads, which is described in Theoretical Analysis of Immobilized-Cell Growth, and compartmentalized growth of immobilized cells are proposed to explain plasmid stability in immobilized cells. 相似文献
24.
The N2O flux from the surface of grass-covered pots was only significant following grass maturing. Removal of the above-ground plant
material resulted in an immediate and long-lasting increase in N2O production in the soil. The results suggest that easily available organic matter from the roots stimulates the denitrification
when the plants are damaged. Grass cutting might therefore result in a marked nitrogen loss through denitrification. The quantitative
effect was equal in soil with and without succinate added. The size of the anaerobic zone around the roots is therefore sufficient
to allow for denitrification activity mediated by increased organic matter availability because of plant cutting. 相似文献
25.
26.
T Skórski M Kawalec J Kawiak 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1987,25(1):23-27
The composition of peritoneal exudate and spleen cells of CD2F1 mice after fourfold i.p. administration of L 1210 leukemia cells treated with cyclophosphamide (L 1210-CY cells) were examined. The number of cells in peritoneal cavity did not increase, however, the spleen weight rose after administration of L 1210-CY cells. The per cent of lymphocytes T was increased 2.5 times but the content of macrophages and lymphocytes B was normal in the peritoneal cavity after L 1210-CY cells injections. In the spleen an 1.4 times increase of the per cent of lymphocytes B, but normal level of macrophages and lymphocytes T were observed. 相似文献
27.
28.
Ulrik Røen 《Hydrobiologia》1987,145(1):125-130
Chydorus arcticus n.sp. (Cladocera: Chydoridae: Chydorinae) is described, figured, and differentiated from the closely relatedC. sphaericus (O.F. Müller, 1785). The known distribution of the species is given, and some aspects of speciation of arctic crustaceans
are pointed out. 相似文献
29.
The effect of hydrogen peroxide on Salmonella typhimurium in whole egg was evaluated. The bactericidal effects observed on the test organism at 5 degrees and 20 degrees C were found to be similar. There was a 99% kill in the presence of 0.5% and 1.0% H2O2. Addition of the test organism and H2O2 after pre-heating the egg material at 40 degrees C for 15 min caused a rapid kill which was 10,000-fold greater than that produced by H2O2 alone. 相似文献
30.
Acute Effect of Ammonia on Branched-Chain Amino Acid Oxidation and Incorporation into Proteins in Astrocytes and in Neurons in Primary Cultures 总被引:2,自引:1,他引:1
14CO2 production and incorporation of label into proteins from the labeled branched-chain amino acids, leucine, valine, and isoleucine, were determined in primary cultures of neurons and of undifferentiated and differentiated astrocytes from mouse cerebral cortex in the absence and presence of 3 mM ammonium chloride. Production of 14CO2 from [1-14C]leucine and [1-14C]valine was larger than 14CO2 production from [U-14C]leucine and [U-14C]valine in both astrocytes and neurons. In most cases more 14CO2 was produced in astrocytes than in neurons. Incorporation of labeled branched-chain amino acids into proteins varied with the cell type and with the amino acid. Addition of 3 mM ammonium chloride greatly suppressed 14CO2 production from [1-14C]-labeled branched chain amino acids but had little effect on 14CO2 production from [U-14C]-labeled branched-chain amino acids in astrocytes. Ammonium ion, at this concentration, suppressed the incorporation of label from all three branched-chain amino acids into proteins of astrocytes. In contrast, ammonium ion had very little effect on the metabolism (oxidation and incorporation into proteins) of these amino acids in neurons. The possible implications of these findings are discussed, especially regarding whether they signify variations in metabolic fluxes and/or in magnitudes of precursor pools. 相似文献