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Interaction effects between the agglomerative externalities affecting the survival of small startups
The purpose of this study is to identify the relationship between the survival of firms and the influence of agglomeration economies on firm location using a mixed effect Cox model considering random effects, given the industrial conditions of South Korea. Each agglomerative externality had a negative effect on the survival proportion of small startups except the related variety of the tertiary sector. However, the interaction effects between each externality and the location potential and among agglomerative externalities mostly played a complementary role to the survivability of startups; however certain effects reduced the survivability, and the effects were differentiated for each industrial sector. This study provides an advanced understanding of small firm performance after entry into the market in developing and developed nations. 相似文献
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Comparison of the canine corneal epithelial cell sheets cultivated from limbal stem cells on canine amniotic membrane,atelocollagen gel,and temperature‐responsive culture dish 下载免费PDF全文
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In this study, a genetically engineered live attenuated Salmonella Enteritidis (SE) vaccine was evaluated for its ability to protect against Salmonella Typhimurium (ST) infection in chickens. The birds were orally primed with the vaccine on the 1st day of life and given an oral booster at 5 wk of age. Control birds were orally inoculated with phosphate-buffered saline. Both groups of birds were orally challenged with a virulent ST strain at 9 wk of age. Compared with the control chickens, the vaccinated chickens had significantly higher levels of systemic IgG and mucosal IgA against specific ST antigens and a significantly greater lymphoproliferative response to ST antigens. The excretion of ST into the feces was significantly lower in the vaccinated group than in the control group on days 9 and 13 d after challenge. In addition, the vaccinated group had significantly fewer pronounced gross lesions in the liver and spleen and lower bacterial counts in the internal organs than the control group after challenge. These data indicate that genetically engineered live attenuated SE may induce humoral and cellular immune responses against ST antigens and may confer protection against virulent ST challenge. 相似文献
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Phan Van Kiem Chau Van Minh Nguyen Tien Dat La Van Kinh Dan Thuy Hang Nguyen Hoai Nam Nguyen Xuan Cuong Hoang Thanh Huong Trinh Van Lau 《Fitoterapia》2010
Phytochemical investigation of the methanol extract of Tinospora cordifolia aerial parts led to the isolation of four new and seven known compounds. The structures of two new aporphine alkaloids, N-formylasimilobine 2-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside (tinoscorside A, 1) and N-acetylasimilobine 2-O-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside (tinoscorside B, 2), a new clerodane diterpene, tinoscorside C (3), and a new phenylpropanoid, sinapyl 4-O-β-d-apiofuranosyl-(1 → 6)-O-β-d-glucopyranoside (tinoscorside D, 6) were determined by extensive spectroscopic methods including FTICR-MS and 1D and 2D NMR. 相似文献
7.
Antioxidative, antimutagenic, and anticarcinogenic activities of rice bran extracts in chemical and cell assays 总被引:4,自引:0,他引:4
Nam SH Choi SP Kang MY Kozukue N Friedman M 《Journal of agricultural and food chemistry》2005,53(3):816-822
Ethanol-water (70:30 v/v) extracts from rice brans removed from seeds of two blackish-purple pigmented (Sanhaehyanghyulla and Suwon 415) and one nonpigmented (Chuchung) brown rice cultivars were evaluated for antioxidative, anti-tumor-promoting, and anticarcinogenic activities in chemical assays and in mammalian cells (human leukemia HL-60, marmoset B lymphoblastoid B95-8, and Chinese hamster V79 lung cells) by the following tests: inhibition of xanthine oxidase activity; chelation of ferrous ions; reduction of potassium ferricyanide; scavenging of superoxide anions, hydroxyl radicals, and intracellular peroxides; inhibition of 4-nitroquinoline N-oxide-induced mutagenesis; and inhibition of phorbol ester-induced tumor promotion. The extracts from the pigmented rice seeds had generally higher activities in all tests than did the extract from the nonpigmented variety. The results suggest that brans from pigmented rice varieties may provide a source of new natural antioxidants and anticarcinogens and that such rice cultivars with high antioxidative potential also provide a genetic resource for the development of new, improved rice cultivars that may make it possible to enhance both the nutritional and medical value of rice-based diets. 相似文献
8.
Lee KT Choi J Jung WT Nam JH Jung HJ Park HJ 《Journal of agricultural and food chemistry》2002,50(15):4190-4193
We isolated a new saponin named codonoposide (1) from the roots of Codonopsis lanceolata (Campanulaceae) and characterized it as 3-O-[beta-D-xylopyranosyl(1-3)-beta-D-glucuronopyranosyl]-3beta,16alpha-dihydroxyolean-28-oic acid 28-O-[beta-D-xylopyranosyl (1-3)-alpha-L-rhamnopyranosyl (1-2)-alpha-L-arabinopyranosyl] ester by chemical, physicochemical, and 2DNMR techniques. Complete hydrolysis of 1 produced a sapogenin (1a), and the partial hydrolysis and further isolation afforded two prosapogenins (1b, 1c). The structures of 1a, 1b, and 1c were found to be 3beta,16alpha-dihydroxyolean-28-oic acid (echinocystic acid, 1a), 3-O-beta-D-glucuronopyranoside of 1a, and 3-O-beta-D-xylopyranosyl (1-3)-beta-D-glucuronopyranoside of 1a, respectively, on the basis of spectroscopic data. On MTT assay, 1a showed marginal cytotoxic activity whereas 1b exhibited more cytotoxicity than 1a. However, the bisdesmosylsaponin 1 exhibited no cytotoxicity (IC(50)>0.3 mM against tested cell lines). This result indicated that glycoside linkage of glucuronic acid at C-3 enhances the cytotoxicity of sapogenin (1a), and additive glycosylation of xylose to 1b strongly enhances the cytotoxicity of 3-O-monosaccharides (1b). Therefore, true forms of codonoposide for the cytotoxicity must be sapogenins or prosapogenins. 相似文献
9.
Kazunori Minamikawa Huynh Cong Khanh Yasukazu Hosen Tran Sy Nam Nguyen Huu Chiem 《Soil Science and Plant Nutrition》2020,66(1):225-234
ABSTRACT Livestock production plays a leading role in agricultural land-use change. Producing biogas from livestock waste and subsequently using the biogas effluent as fertilizer for crops is a promising option to solve environmental problems resulting from expanding livestock production. However, it is difficult to promptly and accurately measure the nitrogen (N) concentration of effluent for farmers in developing countries, making precise N management difficult. The objectives of the current study were (1) to evaluate the feasibility of variable-timing, fixed-rate application of cattle biogas effluent using a leaf color chart (LCC) for rice (Oryza sativa L.) and (2) to determine the optimum LCC threshold for grain yield. We conducted two microcosm experiments in the Mekong Delta of Vietnam in 2018 using eight treatments of N-fertilizer application. In the Zero treatment, we applied no N. In the Estd treatment, we split-applied N as effluent (E) at fixed rate and timing as the standard method. In E2.75, E3.00, E3.25, E3.50, and E3.75, we applied effluent whenever the LCC value went below 2.75, 3.00, 3.25, 3.50, and 3.75, respectively. In U3.25, we applied N as urea (U) whenever the LCC value fell below 3.25. The total effluent-N application rate ranged from 90 to 210 kg N ha?1 season?1. Rice growth was normal but there was a substantial yield gap between the two microcosm experiments due to the seasonal difference in solar radiation. Rice yield tended to increase with increasing LCC threshold. There was a positive linear relationship between LCC and chlorophyll content (SPAD) values (R 2 = 0.73–0.79). Grain yield was well explained (R 2 = 0.70–0.89) by the seasonal mean LCC or SPAD value. Plant total N uptake increased with increasing LCC threshold, but the three calculated indices of N use efficiency (NUE) – apparent N recovery, agronomic NUE, and internal NUE – were not always improved with a higher LCC threshold. Our results showed that the tested variable-timing, fixed-rate strategy for the application of cattle biogas effluent was feasible and the optimum LCC threshold for grain production was 3.75 under the current microcosm conditions. 相似文献
10.
Kim SP Kang MY Kim JH Nam SH Friedman M 《Journal of agricultural and food chemistry》2011,59(18):9861-9869
We investigated antitumor effects of the following four extracts of freeze-dried Hericium erinaceus mushrooms in Balb/c mice intracutaneously transplanted on the backs with CT-26 colon cancer cells: HWE, hot water extraction by boiling in water for 3 h; MWE, microwaving in 50% ethanol/water at 60 W for 3 min; and ACE and AKE, boiling in 1% HCl or 3% NaOH for 2 h. HWE and MWE with a higher content of β-glucans, determined by an assay kit, than ACE and MKE were active in all bioassays. Gas chromatography/mass spectrometry analyses showed the presence of 40, 27, 16, and 13 compounds, respectively, in the four extracts. Daily intraperitoneal (ip) injections of HWE and MWE for 2 weeks significantly reduced tumor weights by 38 and 41%. Tumor regressions were associated with changes in the following cancer biomarkers as compared to phosphate buffer (PBS)-treated control mice: 2.7- and 2.4-fold increases in cytolytic activity of splenic natural killer (NK) cells; restored nitric oxide production and phagocytosis in peritoneal macrophages to 95-98% of normal levels; ~2-fold increase in released pro-inflammatory cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6 from macrophages; and ~56 and ~60% reductions in the number of blood vessels inside the tumor. The pro-angiogenic factors vascular endothelial growth factor (VEGF), cyclooxygenase 2 (COX-2), and 5-lipoxygenase (5-LOX) were also significantly reduced in mRNA and protein expression by tumor genes. Enzyme-linked immunosorbent assay of tumor cells confirmed reduced expression of COX-2 and 5-LOX (32 and 31%). Reduced COX-2 and 5-LOX expression down-regulated VEGF expression, resulting in inhibition of neo-angiogenesis inside the tumors. The results indicate that induction of NK activity, activation of macrophages, and inhibition of angiogenesis all contribute to the mechanism of reduction of tumor size. 相似文献