奶牛产酸乳诊治

由于营养供给不合理,导致的泌乳奶牛发生瘤胃酸中毒,而出现产酸乳现象。本研究通过营养调整,结合药物治疗法,有效地防止了奶牛产酸乳的现象。     

Rapid formation of ontong java plateau by aptian mantle plume volcanism

The timing of flood basalt volcanism associated with formation of the Ontong Java Plateau (OJP) is estimated from paleomagnetic and paleontologic data. Much of OJP formed rapidly in less than 3 million years during the early Aptian, at the beginning of the Cretaceous Normal Polarity Superchron. Crustal emplacement rates are inferred to have been several times those of the Deccan Traps. These estimates are consistent with an origin of the OJP by impingement at the base of the oceanic lithosphere by the head of a large mantle plume. Formation of the OJP may have led to a rise in sea level that induced global oceanic anoxia. Carbon dioxide emissions likely contributed to the mid-Cretaceous greenhouse climate but did not provoke major biologic extinctions.     

Dinosaurs on the north slope, alaska: high latitude, latest cretaceous environments

Abundant skeletal remains demonstrate that lambeosaurine hadrosaurid, tyrannosaurid, and troodontid dinosaurs lived on the Alaskan North Slope during late Campanian-early Maestrichtian time (about 66 to 76 million years ago) in a deltaic environment dominated by herbaceous vegetation. The high ground terrestrial plant community was a mild- to cold-temperate forest composed of coniferous and broad leaf trees. The high paleolatitude (about 70 degrees to 85 degrees North) implies extreme seasonal variation in solar insolation, temperature, and herbivore food supply. Great distances of migration to contemporaneous evergreen floras and the presence of both juvenile and adult hadrosaurs suggest that they remained at high latitudes year-round. This challenges the hypothesis that short-term periods of darkness and temperature decrease resulting from a bolide impact caused dinosaurian extinction.     

Southern hemisphere origin of the cretaceous laytonville limestone of california

New paleomagnetic, paleontologic, and stratigraphic data from outcrops of the Laytonville Limestone (101 to 88 million years old) support a Southern Hemisphere origin. A paleomagnetic megaconglomerate test is statistically significant and suggests magnetization at 14 degrees +/- 5 degrees south, predating Late Cretaceous to Eocene (70 to 50 million years ago) accretion. Rapid Kula plate movement or the existence and demise of a now vanished oceanic plate (or both) are required to accommodate the greater than 50 degrees of poleward displacement implied by the paleomagnetic data. This rapid motion brings into question the validity of a "speed limit" for absolute plate velocity based on present-day plate motions.     

办公室计算机的日常维护

办公室计算机日常使用时简单的软硬件维护和操作,从而使计算机发挥出它的最大性能,更好的满足工作需要.     

Is Semen Analysis Useful to Predict the Odds that the Sperm will Meet the Egg?

Any mammalian spermatozoon that achieves successful in vivo fertilization has to perform almost perfectly in many disparate functions and overcome a series of obstacles imposed by the female reproductive tract. This implies that during formation in the testis and epididymis, the spermatozoa did not incur any morphological, metabolic, immunological or genetic abnormalities. Given that the spermatozoa are such highly differentiated cells, this means that every cellular compartment must not only be intact but must also respond appropriately to intracellular and extracellular signals. Assuming that a spermatozoon possesses this level of perfection, and is able to reach and penetrate an oocyte, it can only be regarded as 'fertile' if the DNA it carries is intact and able to sustain embryonic development. Although the proportion of inseminated spermatozoa that meet these criteria is vanishingly small, the female reproductive tract applies stringent selection criteria during sperm transport and, as a result, the probability of conception around the time of ovulation is very high. If laboratory tests of semen quality could approach the efficacy of the female reproductive tract, it would be possible to predict the odds of spermatozoa meeting the egg; however, this is not possible at present. In this article, I suggest a simple model to illustrate how a battery of laboratory tests could eventually be used to make these predictions.     

园林土方工程施工中要注意的七个问题

园林土方工程施工与园林地形改造的需要有很大的关系,其施工方法可有人力施工、机械化和半机械化施工等.土方调配、施工准备、施工排水与降水、土方开挖与填筑、土方的填筑等方面都是施工中需要严格关注和把控的.