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51.
A comprehensive range of phenylacetic acids substituted with nitro, halogen, methyl, amino, hydroxyl and N-acetylamino groups have been synthesized and their growth-regulating activities assessed in the wheat cylinder, pea curvature and pea segment tests. The influence of substituents on molecular shape is shown to be more important in determining activity than their effects on electron distribution. Studies with 2,6-disubstituted phenylacetic acids have indicated that the most active compounds can attain a certain spatial configuration in which one surface of the molecule, including the plane of the ring system, is flat and the carboxyl group is above with its axis of rotation perpendicular to this surface. Positional requirements for growth-regulating activity in phenylacetic acids are shown to be less important than in the phenoxyacetic and benzoic acids.  相似文献   
52.
THE technique of in vivo activation analysis has been used in the sequential study of whole-body calcium1. Neutrons are produced by bombarding a lithium target with 10 MeV protons from the 1.5 m Nuffield cyclotron. The patients, after being irradiated to a dose of about 1.5 rem, are transferred to a whole-body counter in which the activities induced in calcium, sodium and chlorine are monitored. We briefly describe here a new technique for making in vivo measurements on line by counting during the period of irradiation. In particular we have examined the feasibility of measuring the whole-body nitrogen content and of detecting trace amounts of the toxic element cadmium. Liquid phantoms simulating the conditions in the human body are used for these studies.  相似文献   
53.
The direct and systemic antifungal activity of 100 compounds structurally related to iV-(2, 2, 2-trichloro-i-methoxyethyl)formamide has been measured. Some of the compounds showed either protectant or systemic activity against powdery mildew fungi. Compounds not possessing a terminal formamido group showed little anti-mildew activity and for good systemic activity an alkyloxy or alkylamino side-chain in the molecule appeared to be necessary.  相似文献   
54.
METHYLATED basic amino-acids have been detected in many proteins1 and we report here the methylation of rhodopsin2–5. Bovine rhodopsin has been found to contain MML (?-N-monomethyl lysine), DML (?-N-dimethyl lysine) and 3-MH (3-methyl histidine). Residues of TML (?-N-trimethyl lysine) and DMA (dimethyl arginine) were also detected in an un-characterized protein association with rhodopsin which is solubilized from outer segments by 1 % nonionic detergent ‘Ammonyx LO’. In vitro methylation of the basic residues in bovine rhodopsin was also detected after dissected retinas had been incubated in a nutrient medium containing 3H-(methyl) methionine.  相似文献   
55.
Nutrient Dilution by Starch in CO2-enriched Chrysanthemum   总被引:1,自引:0,他引:1  
Increasing growth irradiance and CO2 generally decreases foliarnutrient concentration on a dry weight basis and increases foliarstarch concentration. However, the extent to which starch concentrations‘dilute’ foliar nutrient concentrations when thelatter are expressed on a dry weight basis is not known. Todetermine the importance of differential starch accumulationin calculating nutrient concentrations on a dry weight basis,leaf nutrient and starch concentrations were measured in Chrysanthemum? morifolium ‘Fiesta’ (Ramat.) cuttings grown atthree irradiance levels and two CO2 levels for eight weeks inboth winter and spring. On a dry weight basis, foliar concentrationsof most nutrients were lower in both seasons as a result ofthe elevated CO2 and irradiance levels, and total dry weightswere higher. Per cent starch was greater at the high CO2 levelin both seasons but was only greater at higher irradiances inthe winter experiment. When starch was subtracted from the leafdry weights, the differences between CO2 and irradiance treatmentsdisappeared with respect to N, P, K, Ca, Mg, S, and B but notfor Fe, Mn, Zn, and Cu. Key words: CO2 enrichment, starch, nutrients, irradiance  相似文献   
56.
PORATH  DAN; GALUN  ESRA 《Annals of botany》1967,31(2):283-290
A method has been described by which floral buds of hermaphroditemelons isolated at various stages from archesporium to preleptotenein the pollen mother cells (PMC) can be grown through to pollen-grainformation in culture. Floral buds cultured for this period ina medium with thymidine-methyl-3H (3H-T) showed incorporationof label into the nuclei of tapetal cells and PMCs. The labelincorporated into the PMC was probably due to pre-meiotic DNAsyn-thesis. In other tissues of the floral buds, 3H-T incorporationproceeded through meiosis. Metabolic and environmental factorsinvolved in normal differentiation of the microsporogenous tissueof floral buds cultured in vitro are discussed.  相似文献   
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DAN W. BROCK 《Bioethics》1995,9(3):269-275
The Human Genome Project will produce information permitting increasing opportunities to prevent genetically transmitted harms, most of which will be compatible with a life worth living, through avoiding conception or terminating a pregnancy. Failure to prevent these harms when it is possible for parents to do so without substantial burdens or costs to themselves or others are what J call "wrongful handicaps". Derek Parfit has developed a systematic difficulty for any such cases being wrongs — when the harm could be prevented only by preventing the existence of the individual who would have a worthwhile life even with the handicap, then bringing him into existence with the handicap does not make him worse off and so does not wrong him. I argue that a non "person-affecting" principle requiring the avoidance of suffering and limited opportunity correctly accounts for cases of wrongful handicaps without requiring that the individuals with the handicap have been made worse off and therefore wronged. It is an advantage, not a difficulty, of this account that it does not imply that the person with the handicap has been wronged or is a victim with a special moral complaint.  相似文献   
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