The Firm as Social Networks: An Organisational Perspective   总被引：1，自引：0，他引：1  

HENRY WAI‐CHUNG YEUNG 《Growth and change》2005,36(3):307-328

ABSTRACT This paper offers an organizational perspective on the firm in new economic geographies. It starts with the premise of the firm as a production function in neoclassical economics and a cost minimisation device in transaction cost economics. By pointing out the inadequacy in these mainstream economic perspectives on the firm, I draw upon recent behavioral and managerial theories to develop a relational conception of the firm as social networks in which actors are embedded in ongoing power relations and discursive processes. In further elaborating this relational perspective on the firm as an organisational device, I show how the firm is governed through social relations among different actors, how it is a site of contested ideologies and political representations among these actors, and how space and geographical scales matter in shaping its social construction. Taken together, this organisational perspective aims to shift our research agenda in urban and regional development from promoting the growth of the firm per se to understanding how the firm serves as a relational institution that connects spatially differentiated actors in different places and regions.  相似文献   

Production of interspecific hybrids between Glycine max and G. tomentella through embryo culture     

Gyu Hwa Chung  Jin Hyeong Kim 《Euphytica》1990,48(2):97-101

Summary Interspecific hybrids have been obtained in an incompatible cross between Glycine max and G. tomentella through the in vitro culture of hybrid embryos. The percentage of successful pod setting in the crosses averaged 12.8% but there were marked differences depending on the soybean cultivar used as the female parent. Hybrid embryos at globular to heart stages were extracted from the embryo sac 15–25 days after pollination and cultured in vitro. Hybrid plants were successfully obtained by culturing the embryos on B5 medium supplemented with 0.1 mg/l IBA followed by culture on B5 medium supplemented with 0.1 mg/l TBA plus 0.25 mg/l 2-iP. The F1 plants resembled the wild male parent in growth form, but had an intermediate leaf shape between that of the parents.  相似文献   

Development of an enzyme-linked immunosorbent assay for the pyrethroid cypermethrin   总被引：4，自引：0，他引：4  

Lee HJ  Shan G  Ahn KC  Park EK  Watanabe T  Gee SJ  Hammock BD 《Journal of agricultural and food chemistry》2004,52(5):1039-1043

A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of cypermethrin was developed. Two haptens, the trans- and cis-isomers of 3-[(+/-)-cyano-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarbonyloxy]methyl]phenoxyacetic acid, were conjugated with thyroglobulin as immunogens. Four antisera were generated and screened against six different coating antigens. The assay that was the most sensitive for cypermethrin was optimized and characterized. The IC(50) for cypermethrin was 13.5 +/- 4.3 microg/L, and the lower detection limit (LDL) was 1.3 +/- 0.5 microg/L. This ELISA had relatively low cross-reactivities with other major pyrethroids, such as deltamethrin, phenothrin, resmethrin, fluvalinate, and permethrin. Methanol was found to be the best organic cosolvent for this ELISA, with an optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters were unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths strongly suppressed the absorbances. To increase the sensitivity of the overall method, a C(18) sorbent-based solid-phase extraction was applied to various domestic and environmental water samples. The water samples, fortified with cypermethrin, were analyzed according to this method. Good recoveries and correlation with spike levels were observed.  相似文献   

Major phenolics in apple and their contribution to the total antioxidant capacity     

Lee KW  Kim YJ  Kim DO  Lee HJ  Lee CY 《Journal of agricultural and food chemistry》2003,51(22):6516-6520

The contribution of each phytochemical to the total antioxidant capacity of apples was determined. Major phenolic phytochemicals of six apple cultivars were identified and quantified, and their contributions to total antioxidant activity of apples were determined using a 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay and expressed as vitamin C equivalent antioxidant capacity (VCEAC). Average concentrations of major phenolics and vitamin C in six apple cultivars were as follows (mg/100 g of fresh weight of apples): quercetin glycosides, 13.20; procyanidin B(2), 9.35; chlorogenic acid, 9.02; epicatechin, 8.65; phloretin glycosides, 5.59; vitamin C, 12.80. A highly linear relationship (r (2) > 0.97) was attained between concentrations and total antioxidant capacity of phenolics and vitamin C. Relative VCEAC values of these compounds were in the order quercetin (3.06) > epicatechin (2.67) > procyanidin B(2) (2.36) > phloretin (1.63) > vitamin C (1.00) > chlorogenic acid (0.97). Therefore, the estimated contribution of major phenolics and vitamin C to the total antioxidant capacity of 100 g of fresh apples is as follows: quercetin (40.39 VCEAC) > epicatechin (23.10) > procyanidin B(2) (22.07) > vitamin C (12.80) > phloretin (9.11) > chlorogenic acid (8.75). These results indicate that flavonoids such as quercetin, epicatechin, and procyanidin B(2) rather than vitamin C contribute significantly to the total antioxidant activity of apples.  相似文献   

粘土作为乳化剂的研究Ⅰ.粘土悬液的pH值与乳浊液稳定性的关系     

薛家骅  陈明伯 《土壤学报》1963,11(3):312-315

固体粉末可以作为乳化剂早在本世紀初就已发现^[1]。由于所得的乳浊液一般地讲液滴较粗,稳定性也差,因而长期以来很少被注意。最近L.N.Mukerjee和S.N.Srivastava等人系統地检查了多种难溶无机化合物和粘土作为工业用和农业喷洒用乳化剂的可能性^[2,3]。但对于粘土粉末作为乳化剂的条件没有深入研究。本文是研究一定pH范围内几种本国粘土的乳化效能。  相似文献   

Sequential establishment of stripe patterns in an expanding cell population     

Liu C  Fu X  Liu L  Ren X  Chau CK  Li S  Xiang L  Zeng H  Chen G  Tang LH  Lenz P  Cui X  Huang W  Hwa T  Huang JD 《Science (New York, N.Y.)》2011,334(6053):238-241

Periodic stripe patterns are ubiquitous in living organisms, yet the underlying developmental processes are complex and difficult to disentangle. We describe a synthetic genetic circuit that couples cell density and motility. This system enabled programmed Escherichia coli cells to form periodic stripes of high and low cell densities sequentially and autonomously. Theoretical and experimental analyses reveal that the spatial structure arises from a recurrent aggregation process at the front of the continuously expanding cell population. The number of stripes formed could be tuned by modulating the basal expression of a single gene. The results establish motility control as a simple route to establishing recurrent structures without requiring an extrinsic pacemaker.  相似文献   

Response: Angiotensin II: Does It Have a Direct Obligate Role in Ovulation?     

Naftolin F  Andrade-Gordon P  Pellicer A  Palumbo A  Apa R  Zreik T  Ki Yoon T  Decherney A 《Science (New York, N.Y.)》1989,245(4920):871

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Pterocarpan profiles for soybean leaves at different growth stages and investigation of their glycosidase inhibitions     

Yuk HJ  Curtis-Long MJ  Ryu HW  Jang KC  Seo WD  Kim JY  Kang KY  Park KH 《Journal of agricultural and food chemistry》2011,59(23):12683-12690

Soybean leaves are eaten as seasonal edible greens in Korea. Analysis of the ethyl acetate extract of these leaves showed that it exhibited potent and selective neuraminidase inhibition, which began at the R3 stage and peaked at R7. Ten pterocarpans, including the new 6a-hydroxypterocarpan 10, were isolated from soybean leaves and their inhibition activities tested against a range of glycosidases. The relationship between structure and enzyme inhibition was investigated: 6a-hydroxypterocarpans exhibited much higher inhibition against neuraminidase (IC(50) = 2.4-89.4 μM) than α-glucosidase (IC(50) = 90.4-?>100 μM). Glyceollin VII (7) displayed 40-fold greater activity (IC(50) = 2.4 μM) against neuraminidase than α-glucosidase (IC(50) = 90.4 μM). On the other hand, coumestanes (1-3) were good α-glucosidase inhibitors (IC(50) = 6.0-42.6 μM). In kinetic analysis, the most potent neuraminidase inhibitors (5-10) were noncompetitive. HPLC analysis indicated that most pterocarpan synthesis began from the R3 stage, and a rapid change of pterocarpan concentrations was observed between the R4 and R7 stages.  相似文献   

Mucosa-associated lymphoid tissue lymphoma of the third eyelid conjunctiva in a dog     

Hong IH  Bae SH  Lee SG  Park JK  Ji AR  Ki MR  Han SY  Lee EM  Kim AY  You SY  Kim TH  Jeong KS 《Veterinary ophthalmology》2011,14(1):61-65

A 4-year-old, neutered female Cocker Spaniel was presented to the veterinary clinic for protrusion of the left third eyelid. When the third eyelids from both eyes were everted, lobulated masses were present on the bulbar surface. The left third eyelid had a larger protrusion. There was no apparent associated ocular or systemic involvement. The tumor of left third eyelid was removed and referred for histological examination. Histologically, there were proliferations of lymphoid follicles surrounded by lymphoid cells forming a marginal zone. Those lymphoid cells occasionally infiltrated into conjunctival epithelium. A few apoptotic bodies with karyopyknotic and karyorrhexic nuclei were observed in the germinal center of lymphoid follicles. Mitotic figures were rare. On immunohistochemistry, tumor cells expressed CD79a but not CD3. A diagnosis of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) of the third eyelid was established based on the histological and immunophenotypical features. At the 1-year follow-up, there was no evidence of recurrence of the mass at the area of excision of the left third eyelid and the remaining tumor of the right third eyelid was still a similar size. The dog still showed no significant findings, except those of the tumor, and no evidence of systemic involvement. To the authors' knowledge, this is the first reported case of MALT lymphoma of the third eyelid in a dog.  相似文献   

Development of an enzyme-linked immunosorbent assay for the detection of the organophosphorus insecticide acephate   总被引：1，自引：0，他引：1  

Lee JK  Ahn KC  Stoutamire DW  Gee SJ  Hammock BD 《Journal of agricultural and food chemistry》2003,51(13):3695-3703

A competitive indirect enzyme-linked immunosorbent assay (ciELISA) for the organophosphorus insecticide acephate, O,S-dimethyl acetylphosphoramidothioate, was developed using a polyclonal antibody. Five different haptens mimicking the analyte were synthesized and conjugated with the carrier proteins bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH) by the N-hydroxysuccinimide active ester and diazotization methods. Polyclonal antibodies raised against hapten-KLH conjugates in rabbits and hapten-BSA conjugates as coating antigens were screened and selected for the assay in the homologous and heterologous ELISA systems. The effects of various assay conditions such as detergent, organic solvents, pH, and preincubation of the mixture of the polyclonal antibody and the analyte on the sensitivity were evaluated. The IC(50) value for acephate was 25 ng/mL in an optimized heterologous system using hapten-4-BSA as a coating antigen and a polyclonal antibody no. 8377 against hapten-1-KLH, showing the detection range of 5-140 ng/mL and the lowest detection limit of 2 ng/mL. The cross-reactivities of the structurally related organophosphorus insecticides, including the major metabolite of the analyte, methamidophos, were less than 1%. Recoveries from the analyte-fortified tap water, mulberry leaves, and lettuce samples in the assay were in the range of 72-121% by simple extraction, concentration, and dilution. These results indicate that the ELISA could be a convenient and supplemental analytical tool for monitoring acephate residues in environmental and agricultural samples.  相似文献