核心期刊简介及其评价功能分析

近年来,围绕核心期刊存与废的争论,一直是图书情报界、学术界和出版界的热门话题,引起业内人士的极大关注。核心期刊的推出缘何会造成如此大的影响？究其原因,主要是由于核心期刊功能的延伸和强化,特别是在成果认定、期刊评价方面的广泛应用,直接影响到期刊编者、作者等诸多方面的利益,因此人们会从各自不同的角度对它持有不同看法。本文分析和探讨了核心期刊概念引发的问题。     

The effect of antibody to caseous lymphadenitis in ewes on the efficacy of vaccination in lambs

The effect of maternal antibody to the toxin of Corynebacterium pseudotuberculosis, produced by caseous lymphadenitis (CLA) in ewes or by vaccinating ewes before lambing, on the efficacy of vaccination against CLA in their lambs was examined. Lambs were allocated to treatments according to either the vaccination history of their dam or level of CLA toxin antibody of their dam. They were vaccinated twice using 2 different inoculation regimes and then artificially infected with CLA organisms. The number of lambs with CLA lesions was assessed at slaughter. In one experiment high levels of CLA toxin antibody activity in ewes were associated with decreased efficacy of CLA vaccination in their lambs, when lambs were vaccinated at 2 and 8 weeks or 8 and 14 weeks of age. In a second experiment the efficacy of lamb vaccination at 8 and 12 weeks, but not at 14 and 18 weeks of age, was decreased. In sheep flocks with a high prevalence of CLA, vaccinating lambs against CLA at less than 10 weeks of age may not produce optimum protection against CLA in lambs. There was no difference in infection rate between lambs from vaccinated and unvaccinated ewes. However, vaccination of lambs at 2 and 8 wks was less effective that vaccination at 8 and 14 weeks, probably due to reduced immunocompetence in young lambs. In sheep flocks where significant numbers of lambs receive their primary vaccination at less than 3 weeks of age vaccination programmes to control CLA in lambs may be less effective.     

Experimental Constraints on Recycling of Potassium from Subducted Oceanic Crust

Petrological experiments on oceanic crust samples characterize the recycling of potassium from mid-ocean ridge basalts and sediments. Metasomatism could develop directly and continuously from subducted potassium-bearing crust from shallow levels to a maximum depth of 300 kilometers. Phengite (a potassium-rich mica) is the principal potassium host at subsolidus conditions. It transports potassium and water to depths of up to 300 kilometers and could yield over the entire depth range potassium-rich fluids or melts (depending on the specific geotherm), which are likely to constitute one of the primary metasomatic agents for generation of calc-alkaline magmas.     

Expression pattern of HIF1alpha and vasohibins during follicle maturation and corpus luteum function in the bovine ovary

The aim of this study was to characterize expression patterns of hypoxia‐inducible factor‐1alpha (HIF1A) and vasohibin family members (VASH1 and VASH2) during different stages of ovarian function in cow. Experiment 1: Antral follicle classification occurred by follicle size and estradiol‐17beta (E2) concentration in the follicular fluid into 5 groups (<0.5, 0.5–5, 5–40, 40–180 and >180 E2 ng/ml). Experiment 2: Corpora lutea (CL) were assigned to the following stages: days 1–2, 3–4, 5–7, 8–12, 13–16 and >18 (after regression) of oestrous cycle and of pregnancy (months 1–2, 3–4, 6–7, >8). Experiment 3: Cows on days 8–12 were injected with a prostaglandin F2alpha (PGF) analogue and CL were collected before and 0.5, 2, 4, 12, 24, 48 and 64 hr after PGF injection. Expression of mRNA was measured by qPCR, steroid hormone concentration by EIA and localization by immunohistochemistry. HIF1A mRNA expression in our study increases significantly in follicles during final maturation. The highest HIF1A mRNA expression was detected during the early luteal phase, followed by a significant decrease afterwards. In contrast, the mRNA of vasohibins in small follicle was high, followed by a continuous and significant downregulation in preovulatory follicles. The obtained results show a remarkable inverse expression and localization pattern of HIF1A and vasohibins during different stages of ovarian function in cow. These results lead to the assumption that the examined factors are involved in the local mechanisms regulating angiogenesis and that the interactions between proangiogenic (HIF1A) and antiangiogenic (vasohibins) factors impact all stages of bovine ovary function.     

Uterus Cryopreservation: Maintenance of Uterine Contractility by the Use of Different Cryoprotocols

Cryopreservation of cells and even tissue is feasible. New exciting findings arise in the promising field of cryobiology, e.g. the cryopreservation of whole ovaries. Uterus cryopreservation would be advantageous not only for experimental biology, but also for transplantation surgery. The objective of this study was to evaluate various cryopreservation protocols as well as various storage temperatures in cryopreservation of whole swine uteri. The used freezing protocol was slow (0.2°C/min) after arterial perfusion with 1%, 5% or 10% dimethyl sulfoxide (DMSO) solution for 10 min and equilibration in this solution for 30 min. Viability of the organs was tested by histological examination, biochemical parameters and by the capability of rhythmical contractions in a perfusion system. Eighty swine uteri were cryopreserved. All uteri that were frozen with 10% and 5% DMSO were viable after thawing for at least 1 h, whereas only 40% survived with the use of 1% DMSO and 0% with the use of 0.5% DMSO, respectively. There was no difference regarding the survival rates after various cryostorage periods for up to 16 weeks or after cryostorage for 2 weeks in −70°C or −130°C. The cryopreservation of a whole organ such as the swine uterus is a valuable method for the study of cryoprotective agents and freezing protocols. This study demonstrates clearly that the perfusion of the organ with cryoprotectants is the only factor which allows the uterus to contract.