THE PRODUCTION OF SOUND BY RADIANT ENERGY     

Bell AG 《Science (New York, N.Y.)》1881,2(49):242-253

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Professor A. Graham Bell's Studies of the Deaf     

Bell AG 《Science (New York, N.Y.)》1890,16(396):135-136

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B1-b2 transition in calcium oxide from shock-wave and diamond-cell experiments     

Jeanloz R  Ahrens TJ  Mao HK  Bell PM 《Science (New York, N.Y.)》1979,206(4420):829-830

Volume and structural data obtained by shock-wave and diamond-cell techniques demonstrate that calcium oxide transforms from the B1 (sodium chloride type) to the B2 (cesium chloride type) structure at 60 to 70 gigapascals (0.6 to 0.7 megabar) with a volume decrease of 11 percent. The agreement between the shockwave and diamond-cell results independently confirms the ruby-fluorescence pressure scale to about 65 gigapascals. The shock-wave data agree closely with ultrasonic measurements on the B1 phase and also agree satisfactorily with equations of state derived from ab initio calculations. The discovery of this B1-B2 transition is significant in that it allows considerable enrichment of calcium components in the earth's lower mantle, which is consistent with inhomogeneous accretion theories.  相似文献   

The efficiency of the bulb and potato aphidRhopalosiphoninus latysiphon (Davidson) as a vector of potato virus V     

A. C. Bell 《Potato Research》1988,31(4):691-694

Summary Experiments to test the ability ofRhopalosiphoninus latysiphon to transmit potato virus V showed a transmission rate of 16 per cent after only two weeks; this was maintained for a further two weeks, beyond which time the rate rose rapidly. A comparison of the mode of inoculation of PVV byR. latysiphon andMyzus persicae suggested that the mechanism may be similar for both species.  相似文献   

10份玉米品种在喀麦隆的适应性研究     

张军  陈顺全  张文庆  李高超  Bell 《作物杂志》2022,38(3):87-66

为探讨我国不同玉米品种在喀麦隆的适应性,以来自中国和喀麦隆的各5个玉米品种为试验材料,在中国援喀麦隆农业技术示范中心考察不同品种的生育期、农艺性状、田间发病情况和产量。结果表明,我国玉米品种生育期为92~94d,喀麦隆品种为110~112d;中国玉米品种株型为半紧凑或紧凑型,整齐度较好,喀麦隆品种均为平展型,整齐度一般;喀麦隆品种的株高和穗位高显著高于中国品种;10个玉米品种均有不同程度的病虫害发生。中国玉米穗行数和行粒数整体高于喀麦隆品种,百粒重则低于喀麦隆品种。喀麦隆品种CHL 103和CMS 9015、中国品种鄂玉30和华盛2000的产量在9.5t/hm²以上,表现出较好的丰产、抗逆性。  相似文献   

Microbial and nematode communities associated with potatoes genetically modified to express the antimicrobial peptide magainin and unmodified potato cultivars     

Maureen O’Callaghan  Emily M. Gerard  Nigel L. Bell  Nick W. Waipara  Lee T. Aalders  David B. Baird  Anthony J. Conner 《Soil biology & biochemistry》2008,40(6):1446-1459

The antimicrobial peptide magainin II has activity against a range of micro-organisms. Tubers harvested from potatoes genetically modified (GM) to express a synthetic magainin gene show improved resistance to the bacterial pathogen Erwinia carotovora. The microbial and nematode communities associated with three magainin-expressing potato lines, their near-isogenic, unmodified parental cultivar (Iwa) and an unrelated cultivar (Karaka) were investigated on field-grown plants. Heterotrophic plate counts were used to enumerate aerobic culturable bacterial and fungal populations, while cultivation-independent analysis of bacterial communities was based on denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from community DNA from phyllosphere, rhizosphere and geocaulosphere (tuber surface) samples. Small but statistically significant differences in the population sizes of culturable bacteria, fungi and yeast were detected among some GM magainin-expressing lines and the unmodified control. However, these differences were typically smaller than the differences between the unmodified parental line control (Iwa) and the unrelated cultivar control (Karaka). Similarly, the difference in the proportion of the nematode population belonging to the fungal feeding trophic group between Iwa and Karaka was greater than that amongst Iwa and its near-isogenic GM lines, and was significantly so for the genus Aphelenchus. The nematode channel ratio (NCR) indicated a more fungal-dominated decomposition channel in soil beneath Karaka compared to Iwa at harvest. In general, eubacterial phylloplane communities were similar for all lines, while the rhizosphere communities associated with two of the three GM lines differed from communities associated with their unmodified parental line control. When roots were senescent, there was no significant difference among potato lines in rhizosphere eubacterial communities or individual trophic groups of the nematode community. Greater diversity was found in geocaulosphere; α-proteobacteria and actinomycete communities of two of the three GM lines differed significantly from their unmodified parental line control and the unrelated cultivar control, while the communities associated with the third GM line were more similar to those of the two control lines. This highlights the importance of testing several GM lines when assessing non-target effects. Results suggest that there is little likelihood of any major sustained non-target effect of genetic modification using a magainin II transgene on plant-associated and soil microflora and function.  相似文献   

High pesticide exposure events among farmers and spouses enrolled in the Agricultural Health Study     

Bell EM  Sandler DP  Alavanja MC 《Journal of agricultural safety and health》2006,12(2):101-116

We completed a nested case-control analysis of factors associated with reporting a high pesticide exposure event (HPEE) by pesticide applicators and spouses during the five years since enrollment in the Agricultural Health Study (AHS). Cases and controls were identified from the 16,415 private pesticide applicators and 14,045 spouses with completed five-year follow-up interviews as of October 2000. Among the applicators, 306 cases with at least one HPEE in the five years since enrollment and 612 controls, randomly selected from those without a reported HPEE, were identified for analysis. Among the spouses, 63 cases were identified and 126 controls were selected. Risk for a new HPEE was increased among applicators reporting at enrollment ever having an HPEE with an odds ratio (OR) of 3.8 (95% CI: 2.7, 5.3). Compared to applicators who applied pesticides fewer than 5 days per year, the ORs ranged from 1.4 (95% CI: 0.9, 2.2) for 6 to 10 days per year to 2.2 (95% CI: 1.4, 3.6) for more than 20 application days per year. The incidence of HPEE among Iowa applicators was much greater (8.8/1000 applicators) than among North Carolina applicators (2.0/1000). Spouses reported fewer HPEEs compared to applicators (2/1000 spouses). Overall, the observed risk factors for new HPEEs among applicators are similar to risk factors observed in previous cross-sectional analyses of HPEE history. Further, only 13% of applicators and 22% of spouses with symptoms resulting from HPEE sought medical care, suggesting that pesticide poisoning surveillance data may seriously underreport the frequency of such events.  相似文献   

Polyunsaturated fatty acid content of wild and farmed tilapias in Thailand: effect of aquaculture practices and implications for human nutrition     

Karapanagiotidis IT  Bell MV  Little DC  Yakupitiyage A  Rakshit SK 《Journal of agricultural and food chemistry》2006,54(12):4304-4310

The total lipid content and fatty acid composition of the muscle tissue of tilapia (Oreochromis niloticus) and of hybrid red tilapia (Oreochromis sp.) from different culture systems and from the natural and artificial environment of Thailand were compared. Wild fish and fish reared under the most extensive conditions had a more favorable fatty acid profile for human consumption as they contained higher proportions of 18:3n-3, 20:5n-3, and 22:6n-3, higher n-3/n-6 PUFA ratios, and lower proportions of 18:2n-6. The muscle tissue of intensively cultured fish was characterized by increased fat deposition that was mainly saturated and monounsaturated fatty acids and 18:2n-6. It is undesirable for the consumer to reduce 20:5n-3 and 22:6n-3 in farmed tilapia and replace them with elevated 18:2n-6. It is recommended that the amount of 18:2n-6 in the feed of the intensively reared tilapia should be reduced by substituting vegetable oils rich in 18:2n-6 with oils rich in 18:1n-9 and/or 18:3n-3.  相似文献   

替米考星对仔猪呼吸道感染的疗效试验   总被引：4，自引：2，他引：4  

卓炳德  张玉西 《中国兽药杂志》2006,40(6):49-51

进行了替米考星对仔猪呼吸道感染的疗效试验,并与泰乐菌素、支炎净、氟苯尼考、克林霉素进行比较。替米考星治疗组仔猪死亡率、有效率、治愈率分别为5.88%、94.12%和88.23%,经统计学分析,效果显著优于对照组(P<0.01);替米考星预防组仔猪发病率、死亡率、有效率和15 d增重分别为4.76%、0、100%和(5.65±1.25)kg,经统计学分析,有效率、治愈率和相对增重显著高于对照组(P<0.01),仔猪发病率、死亡率明显低于对照组(P<0.01)。试验结果表明,替米考星对仔猪呼吸道感染疗效显著,具有临床使用和推广价值。  相似文献   

A survey of contaminated ground with illustrative case histories     

F. G. Bell  D. D. Genske  N. Hytiris  P. Lindsay 《Land Degradation \u0026amp; Development》2000,11(5):419-437

Contaminated ground represents a problem in all the industrialized countries of the world. Contaminated ground may give rise to hazards and that implies a degree of risk which also involves a problem of definition. The investigation of a site which is suspected of being contaminated differs somewhat from a routine site investigation. Sampling of soils, groundwater and gas producing material may be required. Various precautions may be necessary in doing this and operatives may have to wear protective clothing. The first case history considered involves a site investigation for a relief sewer in Glasgow, Scotland. As the site investigation progressed it ran into made‐ground which contained chemical waste. The presence of this waste meant that the nature of the investigation changed and much more stringent safety precautions had to be taken. It also meant that the initial location of the sewer tunnel had to be repositioned at greater depth in uncontaminated sandstone rather than in the superficial deposits above. Two further case histories associated with coal mining in the Ruhr district of Germany are included. The methods involved in investigating these two sites are described, as is their rehabilitation. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献