Bodenmikrobiologische Prozesse und Testaceen (Protozoa) als Indikatoren für Schwermetallbelastung     

Ellen Kandeler  Gabriele Lüftenegger  Sigrid Schwarz 《植物养料与土壤学杂志》1992,155(4):319-322

Soil microbial processes and Testacea (Protozoa) as indicators of heavy metal pollution The influence of the emissions from a copper smelter on soil microbial processes was investigated at 4 meadow sites along a concentration gradient in Brixlegg (Austria). The first site is within 300 m of the source, further sites are situated 1125 m, 2425 m and 5900 m from the smelter. Heavy metal pollution close to the smelter induced a decrease of microbial biomass, respiration, dehydrogenase activity and the related enzyme activities in soil samples (5–10 cm soil depth): Protease, alkaline phosphatase, arylsulfatase, actual and potential nitrification. Thus, soil microbial processes in the 5–10 cm layer appear to be directly affected by heavy metals. Regarding the testate amoebae, their low individual and species numbers at 5–10 cm soil depth obstruct clear trends of this animal group. However, comparing the heavy polluted site with the control area, abundances, species numbers and biomass of testate amoebae slightly decreased at the polluted site (5–10 cm). Contrary to the results in the 5–10 cm layer, most soil microbial processes as well as abundances, species numbers and biomass of testaceans in the upper soil (0–5 cm) seem to be more strongly influenced by the supply of organic substrate than by the content of heavy metals in the soil.  相似文献   

    

Hans Schwarz 《Forstwissenschaftliches Centralblatt》1931,53(5):184-185

Ohne Zusammenfassung  相似文献   

Modelling experts’ judgments on soil compaction to derive decision rules for soil protection—A case study from Switzerland     

Silvia Tobias  Olaf Tietje 《Soil & Tillage Research》2007,92(1-2):129-143

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Interlinked fast and slow positive feedback loops drive reliable cell decisions     

Brandman O  Ferrell JE  Li R  Meyer T 《Science (New York, N.Y.)》2005,310(5747):496-498

Positive feedback is a ubiquitous signal transduction motif that allows systems to convert graded inputs into decisive, all-or-none outputs. Here we investigate why the positive feedback switches that regulate polarization of budding yeast, calcium signaling, Xenopus oocyte maturation, and various other processes use multiple interlinked loops rather than single positive feedback loops. Mathematical simulations revealed that linking fast and slow positive feedback loops creates a "dual-time" switch that is both rapidly inducible and resistant to noise in the upstream signaling system.  相似文献   

Insect juvenile hormone: activity of selected terpenoid compounds     

Schwarz M  Sonnet PE  Wakabayashi N 《Science (New York, N.Y.)》1970,167(3915):191-192

A nuimber of compounds with terpenoid skeletons attached to various functional groups were prepared and tested for their effects as a juvenile hormone in the yellow mealworm Tenebrio molitor. Several of these compounds showed high activity.  相似文献   

Effects of marijuana use     

Schwarz CJ  Kaplan J 《Science (New York, N.Y.)》1973,180(4091):1121-1122

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Temperature Dependence of Wing Abnormality in Tribolium confusum     

Slater JV  Rescigno A  Amer NM  Tobias CA 《Science (New York, N.Y.)》1963,140(3565):408-409

When Tribolium confusum pupae were exposed continuously to temperatures from 10 degrees C to 40 degrees C, the adults which finally emerged exhibited wing abnormalities typical of those obtained with x-irradiation. The data indicate the implication of two processes. Two mathematical models are suggested to account for this phenomenon.  相似文献   

Endocranial features of Australopithecus africanus revealed by 2- and 3-D computed tomography   总被引：4，自引：0，他引：4  

G C Conroy  M W Vannier  P V Tobias 《Science (New York, N.Y.)》1990,247(4944):838-841

The earliest hominid from South Africa, Australopithecus africanus, is known from only six specimens in which accurate assessment of endocranial capacity and cranial venous outflow pattern can be obtained. This places a severe limit on a number of hypotheses concerning early hominid evolution, particularly those involving brain-body size relationships and adaptations of the circulatory system to evolving upright posture. Advances in high-resolution two- and three-dimensional computed tomography (CT) now allow the inclusion of another important specimen to this list, MLD 37/38 from Makapansgat. A new computer imaging technique is described that "reconstructs" the missing portions of the endocranial cavity in order to determine endocranial capacity. In addition, CT evaluation allows assessment of cranial venous outflow pattern even in cases where the endocranial cavity is completely filled with stone matrix. Results show that endocranial capacity in this specimen is less than originally proposed and also support the view that gracile and robust australopithecines evolved different cranial venous outflow patterns in response to upright postures.  相似文献   

Axonal neuregulin-1 regulates myelin sheath thickness     

Michailov GV  Sereda MW  Brinkmann BG  Fischer TM  Haug B  Birchmeier C  Role L  Lai C  Schwab MH  Nave KA 《Science (New York, N.Y.)》2004,304(5671):700-703

In the nervous system of vertebrates, myelination is essential for rapid and accurate impulse conduction. Myelin thickness depends on axon fiber size. We use mutant and transgenic mouse lines to show that axonal Neuregulin-1 (Nrg1) signals information about axon size to Schwann cells. Reduced Nrg1 expression causes hypomyelination and reduced nerve conduction velocity. Neuronal overexpression of Nrg1 induces hypermyelination and demonstrates that Nrg1 type III is the responsible isoform. We suggest a model by which myelin-forming Schwann cells integrate axonal Nrg1 signals as a biochemical measure of axon size.  相似文献   

Steroid binding at sigma-"opioid" receptors   总被引：3，自引：0，他引：3  

S Schwarz  P Pohl  G Z Zhou 《Science (New York, N.Y.)》1989,246(4937):1635-1638

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