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排序方式: 共有1173条查询结果,搜索用时 15 毫秒
71.
72.
PH Katelaris TV Nguyen GJ Robertson R Bradbury MC Ngu 《Canadian Metallurgical Quarterly》1998,28(5):633-638
1. Heterozygous naked neck birds were raised under natural spring (average 21.2 degrees C) and summer temperatures (average 27.1 degrees C) to investigate the influence of dietary energy on broiler performance, carcase yield and nutrient composition of breast meat. 2. Birds were fed on a low energy diet of 12.12 MJ ME/kg, a medium energy diet of 12.96 MJ ME/kg and a high energy diet of 13.79 MJ ME/kg with 2 protein concentrations per energy treatment, 230 and 200 g/kg, from 0 to 3 and 3 to 7 weeks of age, respectively. 3. Summer rearing resulted in a decrease in body weight, body weight gain, carcase weight and carcase part yields of birds. 4. Increasing dietary energy from 12.12 to 13.79 MJ ME/kg increased body weight at 3 and 7 weeks, body weight gains from 0 to 3 and 3 to 7 weeks, carcase weights and relative abdominal fat weights of birds in a linear manner. There was no effect of dietary energy on the nutrient composition of breast meat. 5. It was concluded that there was no differences in dietary energy requirements of heterozygous naked neck birds when grown under natural optimum (21.2 degrees C) and summer temperatures (27.1 degrees C). 相似文献
74.
A Bedekar RM Zink DH Sherman TV Line JF Van Pilsum 《Canadian Metallurgical Quarterly》1998,119(4):677-690
The amino acid sequences of the amidinotransferases and the nucleotide sequences of their genes or cDNA from four Streptomyces species (seven genes) and from the kidneys of rat, pig, human and human pancreas were compared. The overall amino acid and nucleotide sequences of the prokaryotes and eukaryotes were very similar and further, three regions were identified that were highly identical. Evidence is presented that there is virtually zero chance that the overall and high identity regions of the amino acid sequence similarities and the overall nucleotide sequence similarities between Streptomyces and mammals represent random match. Both rat and lamprey amidinotransferases were able to use inosamine phosphate, the amidine group acceptor of Streptomyces. We have concluded that the structure and function of the amidinotransferases and their genes has been highly conserved through evolution from prokaryotes to eukaryotes. The evolution has occurred with: (1) a high degree of retention of nucleotide and amino acid sequences; (2) a high degree of retention of the primitive Streptomyces guanine + cytosine (G + C) third codon position composition in certain high identity regions of the eukaryote cDNA; (3) a decrease in the specificities for the amidine group acceptors; and (4) most of the mutations silent in the regions suggested to code for active sites in the enzymes. 相似文献
75.
OBJECTIVE: Treatment with metformin is occasionally associated with the development of severe lactic acidosis. However, this is usually observed in patients with major contraindications to the drug. In this study, we aimed to determine the prevalence of conditions currently regarded as either contraindications or cautions to the use of metformin in patients with NIDDM. RESEARCH DESIGN AND METHODS: The case notes of metformin-treated NIDDM patients (mean age 62 years) attending a United Kingdom university hospital diabetes clinic over a 3-month period were reviewed according to criteria reflecting a pragmatic view of current prescribing recommendations. RESULTS: Of 89 consecutive patients whose notes could be evaluated in detail, only 41 (46%) had no contraindications or cautions to metformin whatsoever. Concomitant chronic disorders associated with a potentially increased risk of hyperlactatemia were renal impairment (n = 2; plasma creatinine concentrations 1.7 and 2.3 mg/dl, respectively), cardiac failure (n = 2), and chronic liver disease (n = 2). Other potentially relevant disorders included ischemic heart disease (n = 20), clinical proteinuria (n = 14), peripheral vascular disease (n = 22), and pulmonary disease (n = 7). Multiple conditions (i.e., two, three, or four) were present in eight, five, and one patient(s), respectively. CONCLUSIONS: More than half the patients in our series had concomitant conditions or complications conventionally regarded as cautions or contraindications to metformin; approximately 10% had a multiplicity of such conditions. Regular surveillance is necessary to detect the development of complications such as renal impairment. Vigilance is also required in view of the increased risk of major intercurrent illnesses, which may independently disturb lactate metabolism in patients with NIDDM. Metformin should be withdrawn promptly under such circumstances. 相似文献
76.
GA Kosmiadi ZP Abramova TV Vaneeva NM Fomina VIa Gergert EI Shmelev 《Canadian Metallurgical Quarterly》1996,41(4):51-53
The effect of various concentrations of ofloxacin, ciprofloxacin and lomefloxacin on the morphokinetic parameters of the cellular elements of the lung tissue of intact animals (mice, guinea pigs and dogs) was studied under the conditions of the tissue culture. It was shown that in a concentration of 100 micrograms/ml and the exposure time of 24 hours the drugs had no effect on the mobility and structure of the lung tissue cellular elements. When the drugs were used in a concentration of 100 micrograms/ml the mobility rate of the lymphocytes and macrophages proved to by markedly retarded by the end of the 24th hour. In a concentration of 1000 micrograms/ml the drugs killed the cell culture. There were detected no specific differences in the effect of the fluoroquinolones on the cellular elements of the lung tissue of the intact animals. 相似文献
77.
A computer program to generate automatically the stiffness and mass matrices in finite element analysis is introduced. By using programs like this, researchers only need to derive the expressions for the energies (strain or kinetic) and the expressions for the displacements or stresses and their derivatives in terms of nodal variables. Tedious calculations to obtain the matrices are avoided. Such programs would facilitate checking of existing matrices and would encourage researchers to try out new finite element models. 相似文献
78.
RS Bagley TV Baszler ML Harrington GE Pluhar MP Moore RD Keegan SA Greene 《Canadian Metallurgical Quarterly》1995,24(2):122-127
Longitudinal division of the corpus callosum was performed in six normal beagles to determine surgical morbidity. The corpus callosum was divided sagittally on the midline and the effect on neurological function was determined. Five of six dogs were clinically normal within 14 days or less after surgery. One dog had persistent but improving clinical signs consistent with a forebrain disturbance at 30 days after surgery. Overall, minimal morbidity and no mortality was associated with this surgical procedure. Further study is indicated to determine the efficacy of this surgical treatment for seizure control in dogs with idiopathic epilepsy. 相似文献
79.
80.
An ad-hoc sensor network (ASN) is a group of sensing nodes that transmit data over a wireless link to a target node, direct or indirect, through a series of nodes. ASN becomes a high-risk group for several security exploits due to the sensor node’s limited resources. Internal threats are more challenging to protect against than external attacks. The nodes are grouped, and calculate each node’s trust level. The trust level is the result of combining internal and external trust degrees. Cluster heads (CH) are chosen based on the anticipated trust levels. The communications are then digitally signed by the source, encoded using a key pair given by a trustworthy CH, decoded by the recipient, and supervised by verifications. It authenticates the technique by identifying the presence of both the transmitter and the recipient. Our approach looks for a trustworthy neighboring node that meets the trust threshold condition to authenticate the key produced. The companion node reaffirms the node’s reliability by getting the public-key certification. The seeking sensor node and the certification issuer node must have a close and trusting relationship. The results of the proposed hybrid authentication using a node trustworthy (HANT) system are modeled and tested, and the suggested approach outperforms conventional trust-based approaches in throughput, latency, lifetime, and vulnerability methods. 相似文献