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排序方式: 共有1053条查询结果,搜索用时 25 毫秒
881.
Yumi Yoshioka Kimihito Nakamura Haruhiko Horino Shigeto Kawashima 《Paddy and Water Environment》2016,14(1):93-103
Quantitative assessment of the impacts of climate change on groundwater levels is important for sustainable groundwater use. This study examined the Tedori River alluvial fan in Ishikawa Prefecture, Japan, where paddy fields occupy 45 % of the total area. A regional groundwater flow model simulated future groundwater levels in response to 38 climate change projections generated for each of three GCMs, using three GHG emission scenarios with the ELPIS-JP datasets. The numerical groundwater flow model consisted of a 1-D unsaturated water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Variable parameters consisted of daily air temperature, precipitation, humidity, solar radiation, and wind speed, which influence groundwater through infiltration, evapotranspiration, snowfall, and snowmelt. Groundwater levels had both decreasing and increasing trends, depending on climate change. There were more decreasing than increasing trends, and the maximum groundwater drawdown during 2010–2090 was ~1 m. Groundwater level was most sensitive to change in rate of precipitation during the non-irrigation period. Variations of relatively low-intensity precipitation days, when daily precipitation was <10 mm, had an effect on groundwater level. These results contribute to development of adaptive and sustainable groundwater managements (e.g. land use management and pumping strategies) in the future. 相似文献
882.
Maruyama Toshisuke Noto Fumikazu Takimoto Hiroshi Nakamura Kimihito Onishi Takeo 《Paddy and Water Environment》2011,9(4):441-449
The long-term nitrogen pollution load potential (NPLPg) to groundwater from farmlands was examined in the Tedori River Basin.
The NPLPg was estimated using the difference between N in the fertilizer application rate and N outputs in crop yield at 5-yearly
intervals from 1960 to 2005. The total yearly NPLPg of 1,085 t (103 kg) in the 1960s decreased to 774 t by 1975. Thereafter,
the NPLPg gradually increased to 976 t in the 1990s, but decreased again to 369 t in 2005. The NPLPg decreased by 23% for
rice and by 37% for horticultural crops from 1960 to 2005 with an overall decrease of 34%. The NPLPg per unit area was relatively
stable over time for rice, soybean, barley, and horticultural crops, but there were significant differences among them. The
NPLPg for rice ranged from 39 to 85 kg ha−1 year−1 with an average of 65 kg ha−1 year−1 and that of the horticultural crops ranged from 273 to 357 kg ha−1 year−1 with an average of 302 kg ha−1 year−1 The significant long-term changes in the NPLPg suggest that evaluation at a specific point in time is insufficient for an
integrated assessment of groundwater pollution. 相似文献
883.
Zolensky ME Zega TJ Yano H Wirick S Westphal AJ Weisberg MK Weber I Warren JL Velbel MA Tsuchiyama A Tsou P Toppani A Tomioka N Tomeoka K Teslich N Taheri M Susini J Stroud R Stephan T Stadermann FJ Snead CJ Simon SB Simionovici A See TH Robert F Rietmeijer FJ Rao W Perronnet MC Papanastassiou DA Okudaira K Ohsumi K Ohnishi I Nakamura-Messenger K Nakamura T Mostefaoui S Mikouchi T Meibom A Matrajt G Marcus MA Leroux H Lemelle L Le L Lanzirotti A Langenhorst F Krot AN Keller LP Kearsley AT 《Science (New York, N.Y.)》2006,314(5806):1735-1739
The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk. 相似文献
884.
885.
The roles of structural imperfections in InGaN-based blue light-emitting diodes and laser diodes 总被引:2,自引:0,他引:2
S Nakamura 《Science (New York, N.Y.)》1998,281(5379):955-961
REVIEW High-efficiency light-emitting diodes emitting amber, green, blue, and ultraviolet light have been obtained through the use of an InGaN active layer instead of a GaN active layer. The localized energy states caused by In composition fluctuation in the InGaN active layer are related to the high efficiency of the InGaN-based emitting devices. The blue and green InGaN quantum-well structure light-emitting diodes with luminous efficiencies of 5 and 30 lumens per watt, respectively, can be made despite the large number of threading dislocations (1 x 10(8) to 1 x 10(12) cm-2). Epitaxially laterally overgrown GaN on sapphire reduces the number of threading dislocations originating from the interface of the GaN epilayer with the sapphire substrate. InGaN multi-quantum-well structure laser diodes formed on the GaN layer above the SiO2 mask area can have a lifetime of more than 10,000 hours. Dislocations increase the threshold current density of the laser diodes. 相似文献
886.
Shibata K Nakamura T Matsumoto T Otsuji K Okamoto TJ Nishizuka N Kawate T Watanabe H Nagata S Ueno S Kitai R Nozawa S Tsuneta S Suematsu Y Ichimoto K Shimizu T Katsukawa Y Tarbell TD Berger TE Lites BW Shine RA Title AM 《Science (New York, N.Y.)》2007,318(5856):1591-1594
The heating of the solar chromosphere and corona is a long-standing puzzle in solar physics. Hinode observations show the ubiquitous presence of chromospheric anemone jets outside sunspots in active regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their velocity is 10 to 20 kilometers per second. These small jets have an inverted Y-shape, similar to the shape of x-ray anemone jets in the corona. These features imply that magnetic reconnection similar to that in the corona is occurring at a much smaller spatial scale throughout the chromosphere and suggest that the heating of the solar chromosphere and corona may be related to small-scale ubiquitous reconnection. 相似文献
887.
Generation of canine dendritic cells from peripheral blood monocytes without using purified cytokines 总被引:1,自引:0,他引:1
Wijewardana V Sugiura K Oichi T Fujimoto M Akazawa T Hatoya S Inaba M Ikehara S Jayaweera TS Inaba T 《Veterinary immunology and immunopathology》2006,114(1-2):37-48
Dendritic cells (DCs), which differentiate in vitro from peripheral blood monocytes (PBMOs) or bone marrow precursors, are a promising candidate for immunotherapy against cancer. The dog, which suffers common types of cancers along with humans, make an ideal large animal model for cancer studies. Monocyte-derived DCs in the dog have not been well characterized, however, since the appropriate condition for in vitro differentiation has not been established. To tackle this problem, we have developed a conditioned media by culturing T cells with immobilized anti-canine CD3 antibody, and sought to induce differentiation of DCs from PBMOs. When purified CD14+ PBMOs were cultured in the presence of 25% T cell conditioned medium (TCCM), the PBMOs increased size and had extended dendritic processes by day 12 of the culture. The cultured PBMOs were found to increase the expression of MHC class II and CD1a molecules, and significantly increased stimulatory activity for allogeneic T cells in the mixed leukocyte reaction. Moreover, the cells significantly increased their expression of IL-18 and IFN-gamma when stimulated with polyinosinic-polycytidylic acid (Poly (I:C)). The cells have a reduced phagocytic activity, which is a common defect in mature DCs. It follows from these results that TCCM does induce the differentiation of DCs from PBMOs. 相似文献
888.
Taketo OBITSU Masahiko GOTO Toshihisa SUGINO Kohzo TANIGUCHI Kenichiro YUKIZANE Shingo IMOTO Mirei YANAGAWA Mabrouk EL-SABAGH 《Animal Science Journal》2009,80(5):546-555
Four Holstein steers fitted with duodenal cannula were used in a 4 × 4 Latin square design to investigate the effect of the combination of corn silage (CS) and alfalfa hay (AH) in different ratios on the ruminal and intestinal digestion of carbohydrates and feed particle passage rate. Steers were fed mixed diets containing both CS and AH in ratios of 80:20, 60:40, 40:60 and 20:80 on a dry matter basis at 95% of ad libitum feed intake. The increase of AH proportion in diets increased dry matter intake and ruminal digestion of dry matter, non-fiber carbohydrate, neutral and acid detergent fiber linearly. Ruminal digestibility of neutral detergent fiber showed a quadratic response, and total digestibility increased linearly with increasing AH proportion. Digestibility of acid detergent fiber in the rumen was not affected by the dietary treatments, but the total tract digestibility increased as the AH proportion increased. Mean retention time of feed particles in total compartment increased when the AH proportion increased from 20% to 60%, but decreased with further increase of the AH proportion. These results indicate that moderate combinations of CS and AH have an associative effect on ruminal fiber digestion, modifying particle movement in the rumen. 相似文献
889.
Yamasaki M Ishida M Nakamura K Sasaki N Murakami M Kumara WR Tamura Y Lim SY Ohta H Takiguchi M 《Veterinary parasitology》2011,180(3-4):215-225
Antibodies that recognized either Babesia gibsoni or canine red blood cell (RBC) 70-kilodalton (kDa) protein were detected in serum from acutely and chronically B. gibsoni-infected. In those sera, antibodies that reacted with recombinant B. gibsoni and canine heat shock protein 70 (rBgHsp70 and rcHsp70) were detected; therefore, B. gibsoni and canine RBC 70-kDa proteins seemed to be BgHsp70 and cHsp70, respectively. In infected dogs, the amounts of these antibodies increased after infection. Interestingly, polyclonal antibody raised against rBgHsp70 in two rabbits reacted not only with rBgHsp70 but also with rcHsp70 and native cHsp70 from canine RBCs. Because BgHsp70 showed high homology with cHsp70 (70.8%), anti-rBgHsp70 antibody might cross-react with cHsp70. Additionally, the localizations of both BgHsp70 and cHsp70 were observed by indirect fluorescence assay. As a result, cHsp70 was not found on the membrane surface of erythrocytes, suggesting that erythrocytes would not be targets of anti-cHsp70 antibody. Meanwhile, only exoerythrocytic parasites were stained by anti-rBgHsp70 antibody. This result showed that BgHsp70 would be expressed on the surface of parasites during the exoerythrocytic stage. These results indicated that BgHsp70 was a highly immunogenic protein in canine B. gibsoni infection, and that exoerythrocytic parasites might be targets of anti-BgHsp70 antibody. 相似文献
890.
Fujino Y Nakamura Y Kobayashi H Kikuchi K 《The Journal of reproduction and development》2006,52(2):267-275
We examined the relationship between the time elapsed after human chorionic gonadotropin (hCG) administration and developmental stage of porcine embryos after collection. Prepubertal gilts, 7 to 8 months old, were given 1500 IU equine chorionic gonadotropin (eCG) intramuscularly, followed by 500 IU hCG 72 h later. The treated gilts were inseminated artificially on Day 1 (Day 0=the day of hCG administration) and on Day 2. Embryos were collected surgically on Day 6 (140, 144, and 147 h after hCG administration) or on Day 7 (164, 168, and 171 h), and the developmental stages of the collected embryos were examined. From 75.2% (276/367) of the prepubertal gilts treated with hormones, we collected an average of 20.7 embryos per gilt with normal morphology. At 140 h after hCG administration, morulae (54.4%) could be collected. At 144 h, morulae and early blastocysts (57.7% and 28.9%, respectively) were collected. By 147 h, the proportion of embryos at the blastocyst to expanded blastocyst stages had increased (10.0%). From 164 h to 171 h, expanding or expanded blastocysts of more than 200 microm in diameter and hatched blastocysts could be collected. The proportion of hatched blastocysts increased from 3.2% (164 h) to 41.0% (171 h). These results suggests that although the number of ovulations differed among gilts, porcine embryos at the appropriate stages can be collected efficiently by controlling the time elapsed between hCG administration and embryo collection. 相似文献