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1.
Forty-four goats were milked and milk flow recorded without or with 1 min manual prestimulation in early, mid and late lactation. Ultrasound measurements of cross sections of the whole mammary gland were performed in a water bath. In additional experiments with 15 goats, milk flow was recorded and frequent blood samples were taken for the determination of oxytocin and prolactin concentrations. Milk yield increased from the first to the third lactation and decreased markedly during the course of lactation. Average and peak milk flow rates were closely related to the actual milk yield. The ultrasound cisternal area was 27.4 +/- 1.5% of the entire udder half cross section. Milking characteristics were scarcely different without or with prestimulation, although oxytocin was released within 30 s after the start of prestimulation, whereas oxytocin concentrations without prestimulation increased only after the start of milking. Concentrations of prolactin were higher during July and August than in April, and increased similarly with or without prestimulation during milking. In contrast to dairy cows, prestimulation and an opportune release of oxytocin during milking does not significantly influence the course of milk flow in goats, and this is probably because large amounts of cisternal milk allow milk ejection to be induced only after the start of milking without causing bimodal or otherwise reduced milk flow.  相似文献   

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The aim of this study was to investigate whether in the maxilla and in the mandible the structure of the anterior medial sagittal alveolar and basal bone is related to the overbite. A total of 460 untreated adult subjects were divided into four groups with either deep bite, normal overbite, end-to-end bite, or open bite and were compared. The overbite, lower face height, and anterior alveolar and basal midsagittal cross-sectional areas from the maxilla and the mandible were assessed on lateral cephalometric radiographs. An index was calculated, dividing the sagittal by the vertical dimension of the midsagittal cross-sectional area. A deeper bite coincided with smaller lower face height, larger alveolar and basal areas, and a more widened shape of the symphysis. If the lower face height was introduced as a covariable, the open bite group showed significantly smaller maxillary and mandibular alveolar and basal cross-sectional areas compared with the end-to-end group, the normal overbite group, or the deep bite group. Vertical variation of the overbite probably coincides with a relative hyperdevelopment or hypodevelopment of the symphysis.  相似文献   

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The relationship between in vitro sensitivity to antimicrobials and the outcome of treatment was studied in 228 cows with coliform mastitis. All the cows were treated with a preparation containing sulphonamide and trimethoprim, and 197 of them were also treated with a non-steroidal anti-inflammatory drug (NSAID). The relationship between in vitro sensitivity to sulphonamide/trimethoprim and recovery was analysed by multivariate logistic regression. The possible confounding effects of treatment with an NSAID, days in lactation, parity, herd, and type of infecting organism were tested. Only treatment with an NSAID had a significant confounding effect and was included in the final statistical model. The recovery rate of the 165 cows infected by coliforms that were sensitive to sulphonamide/trimethoprim (89.1 per cent) was higher than that of the 63 cows infected by coliforms that were resistant to sulphonamide/trimethoprim (74.6 per cent). The odds ratio of recovery for the cases associated with organisms that were sensitive to sulphonamide/trimethoprim relative to the cases associated with organisms that were resistant to sulphonamide/trimethoprim was 2.75, with a 95 per cent confidence from 1.25 to 5.85. The odds ratio of recovery for the cases treated with an NSAID relative to the cases treated with sulphonamide/trimethoprim only was 2.76 with a 95 per cent confidence interval from 1.12 to 6.79.  相似文献   

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Leiomyosarcomas of the small intestine were found in dogs during experimental induction of gastric carcinoma by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Leiomyosarcomas were found most frequenly in the duodenum and jejunum, and occasionally in the stomach but never in the ileum, colon, or rectum. The leiomyosarcomas developed in all the dogs given 50 mug/ml of MNNG in deionized water to drink but not in dogs fed on porridge food made from standard pellet diet mashed with MNNG at the same concentration in tap water. Intestinal sarcomas developed in 3 months to 5 years after the end of MNNG administration, and frequently metastasized to the liver and/or the peritoneum.  相似文献   

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Degenerate primers corresponding to consensus sequences in the catalytic domains of known fungal adenylate cyclases were used to isolate gene-specific homologs from the Dutch elm disease pathogen Ophiostoma novo-ulmi, the dimorphic human pathogen Candida albicans, and the commercial mushroom Agaricus bisporus. All three fungi gave the expected PCR product of about 390 bp. Computer searches of the databases revealed that the products generated from O. novo-ulmi and C. albicans were highly similar to the adenylate cyclase gene of Magnaporthe grisea, the rice blast fungus (91% and 79%, respectively). The PCR product from the homobasidiomycete A. bisporus, on the other hand, showed 78% similarity to the uac1 gene of the heterobasidiomycete smut fungus, Ustilago maydis. Southern hybridization indicated that all three fungi contain a single adenylate cyclase gene. Our data suggest that PCR will be highly successful for the isolation of adenylate cyclase sequences from other fungi.  相似文献   

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Becoming more competitive as a nation implies that we need to align our vast technological resources with enlightened human resource management to apply these technologies productively. In this article, the status of new workplace technologies is reviewed, and a "macroergonomic" approach is taken to discuss the impact of new technologies on the individual employee, on management methods, and on organizational structure and design. New workplace technologies pose many challenges for industrial and organizational psychologists, including how they may contribute to systematic research aimed toward productivity improvement. The review concludes that technological innovation will not be adopted and thus will not improve U.S. productivity unless a balance is achieved between technological development and human resource management needs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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Using mortality and incidence data from Alameda County, California, this study attempted to determine whether the higher occurrence rate of prostatic cancer among black men as compared with whites in the United States might be explained by racial differences in factors associated with socioeconomic status. Each death or case of prostatic cancer was assigned to a social class based on census tract of residence, and rates by race and socioeconomic status were computed. Comparison of age-specific mortality and incidence rates by socioeconomic status reveals no gradient in either whites or blacks. The higher risk for blacks holds up at almost every age and socioeconomic level. However, the racial differences are less pronounced for incidence than for mortality. Racial differences in the occurrrence of deaths appearing in Part II of the death certificate are also examined.  相似文献   

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We undertook this study to test the hypothesis that early enteral nutrition might reduce the incidence of serious complications after major abdominal surgery. In a randomized double blind prospective trial 30 patients received Nutridrink and 30 patients received placebo through a nasoduodenal feeding tube. On the day of operation the patients were given median 600 ml nutrition/placebo, 60 ml/h. On the first postoperative day the patients received median 1000 ml nutrition/placebo, second day median 1200 ml nutrition, 1400 ml placebo, third postoperative day median 1000 ml nutrition, 1150 ml placebo and 4th postoperative day median 1000 ml nutrition, 800 ml placebo. All patients were followed for 30 days by the same investigator. The two groups were not different with regard to nutritional status and type of operation. The rate of postoperative infectious complications was significantly lower in the nutrition group, 2/30 compared to 14/30 in the placebo group (p = 0.0009). We conclude that early enteral nutrition given to patients after major abdominal surgery is followed by a major reduction in infectious complications.  相似文献   

11.
王洋  崔衡  王征  杨鹤 《钢铁研究学报》2017,29(8):649-653
为了优化RH处理工艺,提高RH精炼后的IF钢的洁净度水平,通过分析全氧含量和夹杂物的控制水平,研究了纯循环和镇静时间对IF钢洁净度的影响。研究表明,RH加入铝粒反应6min后钢液中全氧质量分数降低至24.7×10~(-6)。加入Ti-Fe合金后,全氧质量分数上升至30×10~(-6)。随后RH经合金化后保持6~9min的纯循环时间,全氧质量分数可降低到27×10~(-6)。延长镇静时间至25min,可使全氧质量分数降低到27×10~(-6);通过直线法计算,夹杂物数量由破空时的13.21个/mm2逐渐降低到破空25min时的7.79个/mm2。  相似文献   

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The functional effects of adenosine 5'-triphosphate (ATP), uridine 5'-triphosphate (UTP), adenosine 5'-tetraphosphate (AP4) and the diadenosine polyphosphates P1,P3-diadenosine triphosphate (Ap3A), P1,P4-diadenosine tetraphosphate (Ap4A) and P1,P5-diadenosine pentaphosphate (Ap5A) were studied in two isolated smooth muscle preparations thought to contain P2Y (P2Y1) receptors, the guinea-pig taenia caeci (which relaxes to ATP) and the rat colon muscularis mucosae (which contracts to ATP). In addition, the breakdown of these compounds by the rat colon muscularis mucosae was investigated by high pressure liquid chromatography. In the guinea-pig taenia caeci all the purine nucleotides caused relaxation with a potency order of Ap3A=Ap4A> ATP>AP4=Ap5A, and these relaxations were antagonised by suramin with apparent pA2 values in the region of 5, consistent with activation of a P2Y1 receptor. In the rat colon muscularis mucosae the nucleotides caused contraction with a potency order of Ap3A = Ap4A>ATP=AP4 =Ap5A >UTP. However, while suramin (100 microM) inhibited responses to ATP and UTP at all concentrations of agonist, it only inhibited contractions induced by the higher concentrations of AP4, Ap3A and Ap4A and had little effect on contractions induced by Ap5A. A higher concentration of suramin (1 mM) enhanced contractions induced by ATP but greatly inhibited those induced by UTP and had no effect on responses to the other agonists. The A1 adenosine receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 10 nM) had no effect on responses to ATP or UTP but inhibited responses to Ap3A, Ap4A, Ap5A and AP4. A combination of suramin (1 mM) and DPCPX (10 nM) almost abolished responses to all the agonists. ATP and UTP were rapidly degraded by the rat colon muscularis mucosae while AP4, Ap3A, Ap4A and Ap5A were degraded more slowly, and the major product detected after breakdown of the purine nucleotides was inosine rather than adenosine. The breakdown of all the nucleotides was inhibited by suramin (1 mM), although this inhibition did not achieve statistical significance in the case of ATP. These results show that while the diadenosine polyphosphates appear to act as P2 agonists in the taenia caeci, in the rat colon muscularis mucosae their major action is via adenosine A1 receptors rather than via P2 receptors. In addition, although they are more stable than ATP or UTP, their action in this tissue is clearly affected by their degradation which complicates the effects of suramin.  相似文献   

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Administration of targeted prophylaxis for AIDS-related opportunistic infections has contributed significantly to the recent decrease in mortality among patients with AIDS in the United States. Most reported prophylaxis trials have focused on determining (a) the percentage of cases prevented and (b) the effect of widespread antibiotic use on drug susceptibility. A third phenomenon that is seldom reported on is the attenuating effect of failed prophylaxis on the clinical presentation of opportunistic infections (OIs). With the increasingly widespread use of prophylaxis for OIs, more atypical "breakthrough" cases of opportunistic infections will be seen. Reports of clinical changes are reviewed below. Investigators should routinely report the clinical manifestations of breakthrough cases in all articles pertaining to prophylaxis for opportunistic infections in patients with AIDS.  相似文献   

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为进一步提升RH精炼的冶炼效率,更好与高拉速连铸相匹配,对RH冶炼IF钢过程中加Ti时机和纯循环时间对夹杂物的影响开展了试验研究。结果表明,钢液中T.O质量分数在加Al 5 min后小于0.003 0%;夹杂物的数密度在合金化4~5 min后具有最小值,随后增加纯循环时间,夹杂物的数密度无明显变化。在300 t RH工业生产实践中,Al-Ti间隔时间为2 min、纯循环时间为5 min和Al-Ti间隔3 min、纯循环4 min的处理工艺可以保证钢液中的夹杂物充分上浮去除,夹杂物的数密度为0.7~0.8个/mm2,可以实现RH的高效化精炼。在Al-Ti间隔时间大于1 min、纯循环时间大于3 min的操作条件下钢液中未检测到尺寸大于50μm的夹杂物。基于以上工艺优化,IF钢的RH真空处理时间已经降低至20 min。向钢液中加入Al后主要形成Al2O3夹杂物,加入钛铁合金化后钢液中会形成富[Ti]区域,[Ti]将Al2O3还原而生成Al-Ti氧化物。随着[Ti]在钢液内的扩散以及...  相似文献   

19.
The antiviral activity of ribavirin was studied in hamsters infected with subacute sclerosing panencephalitis (SSPE) virus. Ribavirn did not improve the survival of infected hamsters when administered intraperitoneally at the maximal nonlethal dose of 50 mg/kg/day for 10 days. However, when administered intracranially, ribavirin improved the survival of infected hamsters in a dose-dependent manner. The 50% effective dose was calculated to be 1.4 mg/kg/day, and the selectivity index, based on the ratio of the 50% lethally toxic dose (31 mg/kg/day) to the 50% effective dose, was 22. When begun 12 h, but not 36 h, postinfection, ribavirin at a dose of 10 mg/kg/day completely prevented mortality and inhibited the replication of SSPE virus in brains of infected hamsters. Intrathecal or intraventricular administration of ribavirin should be explored for potential use in the treatment of patients with SSPE.  相似文献   

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Compared to others species Homo sapiens is physically underprivileged as much by his relative weakness than by his lack of natural defense. Only his mental abilities allowed him to cope with the various dangers which threaten him and to rule over the biosphere that he managed to modified for his own benefit. The neolithic revolution which saw the generalization of agriculture and the breeding of animals offered a considerable quantities of resources which lead to a strong demographic growth. All this produced a successions of discoveries which improved his quality of life. Today after an era of quantitative growth the production of the agroalimentary sector enter a qualitative period in which the aim is note only to increase the production of the traditional resources but, by the alteration of the genetic heritage, to improve their properties.  相似文献   

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