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排序方式: 共有185条查询结果,搜索用时 9 毫秒
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W P Cochrane R Greenhalgh N E Looney 《Journal of the Association of Official Analytical Chemists》1976,59(3):617-621
Ethephon (2-chloroethylphosphonic acid) and fenoprop (2-(2,4,5-trichlorophenoxy) propionic acid) may be determined in the same apple sample. After extraction with methanol, 2 separate methylation procedures were required to quantitatively convert each compound. Ethephon was esterified with diazomethane and analyzed by a flame photometric detector in the P-mode. Fenoprop was esterified with boron trifluoride/methanol and analyzed by electron capture gas chromatography. Average recoveries were about 95% at 0.05 ppm for both compounds. The limit of detection was 0.05 ppm for ethephon and 0.01 ppm for fenoprop in a 1 g sample. The persistence of both compounds before and after harvest was studied. Ethephon and fenoprop were applied simultaneously to apple trees at the recommended concentrations of 300 and 20 ppm, respectively. Ethephon residues averaged 1.6, 0.75, and 0.4 ppm at 2 hr, 10 days, and after washing at 13 days, respectively. The corresponding fenoprop residues were 0.70, 0.025, and 0.024 ppm. 相似文献
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Effects of Addition of Tissue‐Type Plasminogen Activator in In Vitro Fertilization Medium on Bovine Embryo Development and Quality 下载免费PDF全文
F Krania E Dovolou CA Rekkas EK Theodosiadou I Pappas GS Amiridis 《Reproduction in domestic animals》2015,50(1):112-120
Plasminogen activators/Plasmin system plays pivotal role in regulating reproductive functions of mammals. Here, we examined the effects of modification of in vitro fertilization medium (IVF medium) with the addition of tissue‐type plasminogen activator (t‐PA), on bovine embryo development and quality, assessed by quantification of expression of various genes related to metabolism, oxidation, implantation and apoptosis. In addition, plasminogen activator activity (PAA) and plasminogen activator inhibition (PAI) were measured in the spent media. After conventional IVM, 2016 cumulus‐oocyte complexes (COCs) were divided into four groups with modified composition of the IVF medium containing t‐PA and/or its inhibitor epsilon‐aminocaproic acid (control, t‐PA, t‐PA+ε‐ACA, ε‐ACA). Presumptive zygotes were cultured for 8 days in synthetic oviductal fluid (SOF) medium; gene expression studies were carried out on morulae and blastocysts. t‐PA alone significantly suppressed cleavage and blastocyst formation rates, but this effect was neutralized by the addition of ε‐ACA. PAA in the treated group was significantly reduced by ε‐ACA, but without total elimination. Significant differences were detected in the expression of genes related to apoptosis and/or cell cycle arrest (BAX, BCL2L1, KAT2B) between embryos produced in t‐PA‐modified media and controls, giving an overall notion that the inferior developmental competence of treated embryos may be attributed to apoptotic phenomena induced by t‐PA. In conclusion, it appears that excessive t‐PA content in the IVF media, suppresses blastocyst formation rate, possibly due to induction of apoptotic phenomena. 相似文献
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Follicular Dynamics in Heifers during Pre-pubertal and Pubertal Period Kept under Two Levels of Dietary Energy Intake 总被引:1,自引:0,他引:1
MA Romano VH Barnabe JP Kastelic CA de Oliveira RM Romano 《Reproduction in domestic animals》2007,42(6):616-622
The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake. 相似文献
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小鼠血清抗磺胺二甲氧嘧啶抗体的研制 总被引:1,自引:0,他引:1
曹盛丰 《上海交通大学学报(农业科学版)》2007,25(2):96-98,119
将磺胺二甲氧嘧啶(SDM)与载体牛甲状腺球蛋白(BTG)偶联,构建SDM完全抗原SDM-BTG。用SDM-BTG免疫小鼠,诱导小鼠产生血清抗SDM抗体。ELISA检测表明:SDM-BTG免疫小鼠所产生的多克隆抗体与SDM-BSA包被抗原的结合有较强的特异性和较高的亲和力。 相似文献
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PC Sereno DB Dutheil M Iarochene HCE Larsson GH Lyon PM Magwene CA Sidor DJ Varricchio JA Wilson 《Science (New York, N.Y.)》1996,272(5264):986-991
Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous. 相似文献
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Complement Titres of Naturally and Artificially Raised Piglets II. Comparison with the Results of Electrophoretic Examinations 下载免费PDF全文
Delma Cochrane C. L'Ecuyer Christine E. Rice 《Canadian journal of veterinary research》1964,28(2):38-42
Serial serum samples from piglets in one naturally-raised and three artificially-raised litters, 19 animals, were examined by cellulose acetate electrophoresis. The electropherograms of all day-old suckling and colostrum deprived piglets showed five definite bands, the first, third, fourth and fifth corresponding in position to the albumin, alpha-, beta- and gamma-globulin regions for adult pig serum. The second, well-defined band was located between the albumin and main alpha-globulin bands. This component, considered to be alpha1-globulin or fetuin, was no longer visible as a distinct band in the electrophoretic pattern for sera of three-week old suckling piglets or of five-week old artificially-raised piglets. No consistent relationship was observed between the rate of increase in haemolytic complement titre and the proportional changes in the various categories of serum globulins. 相似文献
10.
PC Sereno AL Beck DB Dutheil B Gado HCE Larsson GH Lyon JD Marcot OWM Rauhut RW Sadleir CA Sidor DD Varricchio GP Wilson JA Wilson 《Science (New York, N.Y.)》1998,282(5392):1298-1302
Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous. 相似文献