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排序方式: 共有860条查询结果,搜索用时 296 毫秒
101.
Kazuhiro Kawai Tomohito Hayashi Yoshio Kiku Tomoyuki Chiba Hajime Nagahata Hidetoshi Higuchi Tetsu Obayashi Seigo Itoh Ken Onda Sachiko Arai Reiichiro Sato Toshio Oshida 《Animal Science Journal》2013,84(12):805-807
Somatic cell counts (SCC) measurements are typically performed using quantitative methods, such as the Breed method (Breed) and the Fossomatic method (FSCC). The DeLaval cell counter (DCC) developed recently is a quantitative somatic cell counter with a low initial cost and superior portability. However, since the DCC was specifically developed for measuring SCC of ≤ 4 × 106 cells/mL milk from bulk tanks or individual cows, its reliability for estimating SCC that exceed this concentration has not yet been clarified. This study therefore examined whether it is possible to accurately measure SCC by diluting milk samples with initial SCC of 4 × 106 cells/mL, as seen in clinical mastitis milk. We collected milk samples from 99 quarters of 99 Holstein cows with clinical mastitis. These milk samples were diluted 10‐fold with saline and thoroughly mixed before performing SCC measurement with the DCC. The correlation coefficients of SCC measured by the FSCC, Breed and DCC methods indicated strong correlations between each pair of methods. The findings showed that DCC can be used to identify bovine clinical mastitis milk and is useful as a quantitative SCC measurement device on farm sites. 相似文献
102.
The aim of the present study was to clarify the effect of photoperiod on secretory patterns of growth hormone (GH) in male goats. Adult male goats were kept at 20°C with an 8‐h or 16‐h light photoperiod, and secretory patterns of GH secretion were compared. In addition, plasma profiles of prolactin (PRL), insulin‐like growth factor‐I (IGF‐I) and testosterone (T) were also examined to characterize GH secretion. GH was secreted in a pulsatile manner. There was no significant difference in pulse frequency between the 8‐h and 16‐h photoperiods. However, GH pulse amplitude tended to be greater in the group with the 16‐h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16‐h photoperiod (P < 0.05). The GH‐releasing response to GH releasing hormone was greater in the 16‐h than 8‐h photoperiod (P < 0.05). Plasma PRL and IGF‐I levels were higher in the 16‐h than 8‐h photoperiod (P < 0.05). In contrast, plasma T levels were lower in the 16‐h photoperiod (P < 0.05). These results show that a long light photoperiod enhances the secretion of GH as well as PRL and IGF‐I, but reduces plasma T concentrations in male goats. 相似文献
103.
Takashi Otoda Keiji Sakamoto Muneto Hirobe Jamsran Undarmaa Ken Yoshikawa 《Journal of Forest Research》2013,18(1):82-92
We investigated the effects of disturbances on the dynamics of white birch-dominated forests at the southern boundary of the Mongolian forest-steppe. Dendroecological techniques were used to assess regeneration patterns and recent mortality trends in three stands with no evidence of recent anthropogenic disturbance (undisturbed) and four stands with evidence of cutting or fire (disturbed). In the undisturbed stands, only one distinct stem establishment was observed in the period between 1910 and 1950, and no establishment has been observed since then. In the disturbed stands, however, high establishment mainly by sprouting was observed in the period between 1960 and 1980. Percentages of standing dead stems were higher in the undisturbed stands than in the disturbed stands. Mean ages at death in the undisturbed stands were ≥70 years old. The high mortality was likely induced by the death of smaller stems due to light competition, whereas the mortality of larger stems was likely the result of tree senescence. In summary, the undisturbed stands seem to be in danger of decline due to a lack of regeneration during the last half of the previous century and recent high mortality rates of older stems, while the disturbed stands may be maintained for the next several decades by the younger cohort established between 1960 and 1980. White birch-dominated forests at the southern boundary of Mongolian forest-steppe have probably relied on relatively short disturbance intervals in the past because of the disturbance-dependent regeneration trait and relatively short longevity of Betula species. 相似文献
104.
Ken Watanabe Yasuhiro Matsushita Isao Kobayashi Naohiro Kuroda 《Journal of Wood Science》2013,59(2):112-118
Sugi (Cryptomeria japonica D. Don) lumber is known to have a large variability in final moisture content (MCf) and is difficult to dry. This study assessed the capability of artificial neural networks (ANNs) to predict the MCf of individual wood samples. An ANN model was developed based on initial moisture content, basic density, annual ring orientation, annual ring width, heartwood ratio and lightness (L * in the CIE L * a * b * system). The performance of the ANN model was compared with a principal component regression (PCR) model. The ANN model showed good agreement with the experimentally measured MCf with a higher correlation coefficient (r) and a lower root mean square error (RMSE) than the PCR model, demonstrating the importance of nonlinearity of the variables and the higher capability of the ANN model than the PCR model. By adding redness (a * ) and yellowness (b * ) and drying time to the input variables of ANNs, r and RMSE values were improved to 0.98 and 1.2 % for the training data set, and 0.85 and 2.2 % for the testing data set, respectively. Although the developed ANNs are available under the limited conditions of this study, our results suggest that the ANNs proposed offer reliable models and powerful prediction capability for the MCf, even though wood properties vary considerably and their complex interrelations are not fully elucidated. 相似文献
105.
106.
Okajima Kenji Nagaoka Seiya Islam Mohammad Raihanul Ito Ryouei Watanabe Ken 《Paddy and Water Environment》2020,18(2):345-353
Paddy and Water Environment - Repairs of concrete irrigation channels in Japan are guided to a large extent by the degree to which their walls have degraded over decades of use. Current methods of... 相似文献
107.
本研究以黑河下游额济纳旗成熟的河岸胡杨林为对象,分析不同年龄胡杨(Populus euphratica)的年轮宽度序列与不同时间尺度环境因子的关系。结果表明:①在年尺度上,气温是影响胡杨径向生长的主要因子,但不同年龄胡杨对气温的响应有所不同。②在季节尺度上,休眠季气温越高越有利于壮龄胡杨的径向生长,而生长季气温越高越不利于老龄胡杨的径向生长。③在月尺度上,前一年3月和当年9月的平均气温越高,对壮龄胡杨的径向生长越有利,而当年10月平均气温越高,对老龄胡杨的径向生长越不利;前一年7月径流量的增加对老龄胡杨的径向生长有利,而当年2月径流量的增加对壮龄胡杨径向生长有利。综上所述,在季节和年等相对较长的时间尺度上,气温是影响胡杨径向生长量的主要因素,随着时间尺度的缩小,胡杨对环境因子的响应更为细化,并且表现出一定的滞后效应。径流量作为重要的环境因子在月尺度上才突显出来,前一年7月和当年2月的径流补给对胡杨径向生长有极大的促进作用。因此,在黑河统一调度管理过程中,可通过适度调增2月和7月洪水的下泄量来满足胡杨径向生长对水分的需求。 相似文献
108.
109.
Taisuke Kitano Takeshi Kobayashi Soichiro Yamaguchi Ken‐ichi Otsuguro 《Journal of veterinary pharmacology and therapeutics》2019,42(2):243-247
Xylazine, the classical α2‐adrenoceptor (α2‐AR) agonist, is still used as an analgesic and sedative in veterinary medicine, despite its low potency and affinity for α2‐ARs. Previous pharmacological studies suggested that the α2A‐AR subtype plays a role in mediating the clinical effects of xylazine; however, these studies were hampered by the poor subtype‐selectivity of the antagonists used and a lack of knowledge of their bioavailability in vivo. Here, we attempted to elucidate the role of the α2A‐AR subtype in mediating the clinical effects of xylazine by comparing the analgesic and sedative effects of this drug in wild‐type mice with those in α2A‐AR functional knockout mice using the hot‐plate and open field tests, respectively. Hippocampal noradrenaline turnover in both mice was also measured to evaluate the contribution of α2A‐AR subtype to the inhibitory effect of xylazine on presynaptic noradrenaline release. In wild‐type mice, xylazine (10 or 30 mg/kg) increased the hot‐plate latency. Furthermore, xylazine (3 or 10 mg/kg) inhibited the open field locomotor activity and decreased hippocampal noradrenaline turnover. By contrast, all of these effects were abolished in α2A‐AR functional knockout mice. These results indicate that the α2A‐AR subtype is mainly responsible for the clinical effects of xylazine. 相似文献
110.
Invertebrate drift is one of several fundamental ecological processes in streams. However, little is known about the dynamics of invertebrate drift in Kenyan streams. In this study, we assessed invertebrate drift in two rivers, i.e. Njoro and Kamweti, that differ in the level of anthropogenic disturbances, between February and March, 2016. The aim was to evaluate the effect of river sampling duration (5, 10, 15, 20 and 25 min) and sampling period (day or night) on invertebrate drift densities. The 5-minute sampling period resulted in significantly higher mean drift densities than the other time intervals in both rivers. The highest mean drift density (2.0 ± 0.9 individuals m?3) was recorded at the Njoro River during the day, whereas the lowest drift density (0.3 ± 0.2 individuals m?3) was recorded at the Kamweti River during the day. A strong nocturnal drift pattern was noted at the less disturbed river (Kamweti). The present results suggest that anthropogenic perturbations influence invertebrate drift densities, and sampling duration and sampling period are important factors to consider when sampling invertebrate drift. 相似文献