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21.
Summary The anaesthetic effects of intravenous tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg (TK) and tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg-xylazine 0.11 mg/kg (TKX) were evaluated in six wethers. Heart rate, respiration rate, arterial blood pressure, and the electrocardiogram were monitored during anaesthesia. Analgesia was tested by electrical stimulation in the left flank. Atropine (0.03 mg/kg) was given intramuscularly before induction, but after recording of baseline heart rate and respiratory rate. The duration of analgesia was 28.7 ± 6.9 min with TK and 82.8 ± 26.6 min with TKX. Heart rate increased significantly within 5 min after TK or TKX administration. Respiratory rate remained unchanged after TK administration, but increased significantly from 5 to 45 min after TKX administration. Arterial blood pressure decreased significantly at 15 min with TK and 30 min with TKX. Sheep remained recumbent for 201 min with TK and 166 min with TKX. All recovered uneventfully. We conclude that either TK or TKX may be used for anaesthetising sheep.  相似文献   
22.
Hyperactivated Motility in Sperm   总被引:5,自引:0,他引:5  
Hyperactivation is a movement pattern seen in sperm at the site and time of fertilization in mammals. It may be critical to the success of fertilization, because it enhances the ability of sperm to detach from the wall of the oviduct, to move around in the labyrinthine lumen of the oviduct, to penetrate mucous substances and, finally, to penetrate the zona pellucida of the oocyte. The movement of hyperactivated sperm appears different under different physical conditions and in different species, but basically it involves an increase in flagellar bend amplitude and, usually, beat asymmetry. Presumably, a signal or signals exist in the oviduct to initiate hyperactivation at the appropriate time; however, none has yet been identified with certainty. While the signal transduction cascade regulating hyperactivation remains to be completely described, it is clear that calcium ions interact with the axoneme of the flagellum to switch on hyperactivation. Although hyperactivation often occurs during the process of capacitation, the two events are regulated by somewhat different pathways.  相似文献   
23.
WZ Li  SS Xie  LX Qian  BH Chang  BS Zou  WY Zhou  RA Zhao  G Wang 《Science (New York, N.Y.)》1996,274(5293):1701-1703
Large-scale synthesis of aligned carbon nanotubes was achieved by using a method based on chemical vapor deposition catalyzed by iron nanoparticles embedded in mesoporous silica. Scanning electron microscope images show that the nanotubes are approximately perpendicular to the surface of the silica and form an aligned array of isolated tubes with spacings between the tubes of about 100 nanometers. The tubes are up to about 50 micrometers long and well graphitized. The growth direction of the nanotubes may be controlled by the pores from which the nanotubes grow.  相似文献   
24.
The aim of this study was to document the expression and localization of VEGF system comprising of VEGF isoforms (VEGF 120, VEGF 164 and VEGF 188) and their receptors (VEGFR1 and VEGFR2) in buffalo corpus luteum (CL) obtained from different stages of the oestrous cycle. Real‐time RT‐PCR (qPCR), Western blot and immunohistochemistry were applied to investigate mRNA expression, protein expression and localization of examined factors. In general, all the components of VEGF system (the VEGF isoforms and their receptors) were found in the water buffalo CL during the oestrous cycle. The mRNA as well as protein expression of VEGF system was highest during the early and mid‐luteal phase, which later steadily decreased (p < 0.05) after day 10 to reach the lowest level in regressed CL. As demonstrated by immunohistochemistry, VEGF protein was localized predominantly in luteal cells; however, VEGFR1 and VEGFR2 were localized in luteal cells as well as in endothelial cells. In conclusion, the dynamics of expression and localization of VEGF system in buffalo corpora lutea during the luteal phase were demonstrated in this study, indicating the possible role of VEGF system in the regulation of luteal angiogenesis and proliferation of luteal as well as endothelial cells through their non‐angiogenic function.  相似文献   
25.
The current study investigated the possibility of using the AMH concentration as a predictor of the ability of Korean Hanwoo cows to produce cumulus‐oocyte complexes, embryos that survive after transfer as well as the pregnancy outcome of surrogates. Eight sessions of ovum pick‐up (OPU) were performed with 19 donor cows at an interval of 3–4 days. Antral follicle count (AFC), oocyte quality and in vitro embryo development were recorded for each cow. Embryos produced from cows with different AMH profiles were transferred into recipients (n = 96). Cows in the high (≥0.25 ng/ml) and intermediate (0.1≥ to <0.25 ng/ml) AMH groups had a significantly higher AFC per OPU session (20.40 ± 1.36 and 16.91 ± 1.52, respectively; mean ± standard deviation) than cows in the low AMH group (<0.1 ng/ml; 12.19 ± 2.14). In addition, more cumulus‐oocyte complexes per donor were recovered in the high (11.46 ± 1.22) and intermediate (7.38 ± 0.83) AMH groups than in the low AMH group (4.77 ± 0.44). The percentage of oocytes reached blastocyst stage was significantly higher in the intermediate (47.0%) and high (38.5%) AMH groups than in the low AMH group (32.3%). The number of embryos produced per cow was higher in the high (3.9 ± 0.2) and intermediate (6.9 ± 0.6) AMH groups than in the low AMH group (2.2 ± 0.3). The percentage of embryos that gave birth to viable calves when transferred into recipients was higher for those derived from cows in the intermediate AMH group (50.7%) than for those derived from cows in the low (35.7%) and high (36.4%) AMH groups. In conclusion, a single measurement of AMH concentration predicted the in vitro embryo production potential of donor Korean native cows before OPU and is linked with embryo viability after transfer into recipients.  相似文献   
26.
A family of mesoporous molecular sieves (denoted MSU-G) with vesiclelike hierarchical structures and unprecedented thermal (1000 degreesC) and hydrothermal stabilities (more than 150 hours at 100 degreesC) associated with high SiO4 cross-linking was prepared through a supramolecular assembly pathway that relies on hydrogen bonding between electrically neutral gemini surfactants of the type CnH2n+1NH(CH2)2NH2 and silica precursors derived from tetraethylorthosilicate. The vesicle shells are constructed of one or more undulated silica sheets that are about 3 nanometers thick with mesopores (average diameters from 2.7 to 4.0 nanometers) running both parallel and orthogonal to the silica sheets, which makes the framework structure bicontinuous and highly accessible. Catalytic metal ion centers [for example, Ti(IV) and Al(III)] have been incorporated into the framework with the retention of hierarchical structure.  相似文献   
27.
A search was made for 26Mg (26Mg*) from the decay of 26Al (half-life = 0.73 million years) in Al-rich objects from unequilibrated ordinary chondrites. Two Ca-Al-rich inclusions (CAIs) and two Al-rich chondrules (not CAIs) were found that contained 26Al when they formed. Internal isochrons for the CAIs yielded an initial 26Al/27Al ratio [(26Al/27Al)0] of 5 x 10(-5), indistinguishable from most CAIs in carbonaceous chondrites. This result shows that CAIs with this level of 26Al are present throughout the classes of chondrites and strengthens the notion that 26Al was widespread in the early solar system. The two Al-rich chondrules have lower 26Mg*, corresponding to a (26Al/27Al)0 ratio of approximately 9 x 10(-6). Five other Al-rich chondrules contain no resolvable 26Mg*. If chondrules and CAIs formed from an isotopically homogeneous reservoir, then the chondrules with 26Al must have formed or been last altered approximately2 million years after CAIs formed; the 26Mg*-free chondrules formed >1 to 3 million years later still. Because 26Mg*-containing and 26Mg*-free chondrules are both found in Chainpur, which was not heated to more than approximately400°C, it follows that parent body metamorphism cannot explain the absence of 26Mg* in some of these chondrules. Rather, its absence indicates that the lifetime of the solar nebula over which CAIs and chondrules formed extended over approximately5 million years.  相似文献   
28.
Supplementation of exogenous growth hormone (GH) during prepuberty advances onset of spermatogenesis in boars, but the mechanism of action is unknown. The present study is an investigation of the presence and characteristics of testicular growth hormone receptors (GHR). A total of 36 boars were castrated, three boars every 10 days, between the ages of 10 and 120 days. Testicular membrane preparations of 10, 20, 30, 50, 70, 100 and 120‐day‐old boars were used to determine 125I‐bGH binding and Scatchard analysis. Liver from a 60‐kg barrow was used for comparison. Specific 125I‐bGH binding to testicular membrane preparations occurred in all age groups with the exception of 20‐day‐old boars at levels of 30–40% of liver binding. At 30 days of age the unlabelled bGH at 1.1 ng/tube achieved half maximal inhibition (ID50). Results of Scatchard analysis indicated a single class of binding sites. Binding affinity was 2.89 × 109m with a binding capacity of 12 fmole/mg membrane protein. The results from this study suggest that GH may act directly on the cells of the prepubertal boar testis.  相似文献   
29.
30.
A. SÜSS  B. GRAMPP 《Weed Research》1973,13(3):254-266
Zusammenfassung. Um den Einfluß verschiedener Bodenmischungen auf die Aufnahme von adsorbiertem [14C]-markíertem Monolinuron zu verfolgen, wurden jeweils 30, 45, 60, 73 und 90 g Monolinuron-behandelter Boden (0,42-0,53 μg Monolinuron/g Boden) mit unbehandeltem auf 100 g aufgefüllt und damit 15.4–67.1 μg adsorbiertes Monolinuron eingesetzt. Die Aufnahme durch Senipflanzen wurde in Neubauerversuchen während 24 Tagen verfolgt. In 3 Anbauperioden wurden 1.17–9.74 μg aufgenommen. Der überwiegende Teil blieb jedoch an den Boden adsorbiert. Bei einer Bilanzerstellung konnten 99% der zu Versuchsbeginn eingesetzten Monolinuronmenge wieder gefunden werden, Durch den Sorptionsprozeß wurde Monolinuron chemisch nicht vcerändert. Ebenso kann das Ausgangsmolekül in der Pflanze nachgewiesen werden. Die nachweisbare Monolinuronmenge in der Pflanzensubstariz wird umso geringer, je weiter die Aufnahmeintensität zurürkgeht. Über eine Isotopen-Austauschreaktion wurde versucht, das pflanzenverfügbare Monolinuron zu messen.
The uptake of adsorbed monolinuron in the soil by mustard plants  相似文献   
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