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The anticonvulsant effect of either phenobarbital or dilantin was potentiated by exogenous glycine in DBA/2 audiogenic seizure mice and in 3-mercaptopropionic acid-induced seizures. In seizures caused by pentylenetetrazol, glycine potentiated the anticonvulsant effect of phenobarbital only slightly; in combination with dilantin, which was ineffective by itself, it did not have an effect. Valproic acid, in large doses, prevented 3-mercaptopropionic acid-induced seizures; glycine did not potentiate its effect. Glycine thus potentiates anticonvulsant effects, but only of some drugs and only in some of the seizure models. This suggests that the mechanism of the anticonvulsant effect of glycine is similar to that of some of the anticonvulsant drugs such as dilantin and different from others, and that this mechanism is not effective in all seizure models.  相似文献   

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Global competition, advancements in technology and ever changing customers’ demand have made the manufacturing companies to realize the importance of flexible manufacturing systems (FMS). These organizations are looking at FMS as a viable alternative to enhance their competitive edge. But, implementation of this universally accepted and challenging technology is not an easy task. A large number of articles have been reviewed and it is found that the existing literature lacks in providing a clear picture about the implementation of FMS. In this paper, work of various researchers has been studied and it is found that it is really a very difficult task for any organization to transform into FMS on the basis of existing research results. A wide gap exists between the proposed approaches/algorithms for the design of different components of FMS and the real-life complexities. Besides describing the gap in various issues related to FMS, some barriers, which inhibit the adaptation and implementation of FMS, have also been identified in this paper.  相似文献   

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Biologists routinely compare inferences about the order of evolutionary branching (phylogeny) with the order in which groups appear in the fossil record (stratigraphy). Where they conflict, ghost ranges are inferred: intervals of geological time where a fossil lineage should exist, but for which there is no direct evidence. The presence of very numerous and/or extensive ghost ranges is often believed to imply spurious phylogenies or a misleadingly patchy fossil record, or both. It has usually been assumed that the frequency of ghost ranges should increase with the age of rocks. Previous studies measuring ghost ranges for whole trees in just a small number of temporal bins have found no significant increase with antiquity. This study uses a much higher resolution approach to investigate the gappiness implied by 1,000 animal and plant cladograms over 77 series and stages of the Phanerozoic. It demonstrates that ghost ranges are indeed relatively common in some of the oldest strata. Surprisingly, however, ghost ranges are also relatively common in some of the youngest, fossil-rich rocks. This pattern results from the interplay between several complex factors and is not a simple function of the completeness of the fossil record. The Early Palaeozoic record is likely to be less organismically and stratigraphically complete, and its fossils -- many of which are invertebrates-may be more difficult to analyse cladistically. The Late Cenozoic is subject to the pull of the Recent, but this accounts only partially for the increased gappiness in the younger strata.  相似文献   

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Twenty strains ofThermomonospora, isolated from the environments of patients with hypersensitivity pneumonitis or received from culture collections or other workers, were studied for their detailed morphological, physiological, and immunological characteristics. The species studied includedThermomonospora fusca, T. alba, T. curvata, T. mesophilia, andT. mesouviformis. The results indicate that several species can be differentiated by various criteria studied; however, two species,T. fusca andT. alba, could not be separated from one another by any of the tests or methods used in the study.  相似文献   

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On the accuracy of some mark-recapture estimators   总被引:1,自引:0,他引:1  
D. A. Roff 《Oecologia》1973,12(1):15-34
Summary The behaviour of the mark-recapture estimators of Petersen, Bailey (triple catch) and Jolly and Seber are examined theoretically and empirically by means of simulation techniques. The correlation between the parameter and its associated variance is shown to be significant for all the estimators. This correlation makes the estimated variance an insensitive measure of the accuracy of the estimate except at very high sampling intensities. Such sampling intensities are rarely achieved in experimental work and so the method of mark-recapture must be considered of very limited use. At the sampling intensities necessary to give a coefficient of variation of less than 0.05 it does not seem likely that the correlation between and its variance will produce serious underestimation but the minimum confidence limits are recommended.  相似文献   

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On the interpretation of some planktonology equations   总被引:1,自引:0,他引:1  
D. A. Voronov 《Oecologia》1991,88(2):303-304
Summary The concept of the mean value of a function is used to interpret some population-dynamics equations. The well-known formula for the per capita growth rate r gives a precise mean value for any (not only exponentially growing) populations. This result is used to derive the birth and death rate equations of Paloheimo (1974) with minimal initial limitations.Abbreviations t time - N number of animals - E number of eggs - r specific (i.e. per capita) population growth rate - b specific birth rate - d specific death rate - D duration of embryonic development  相似文献   

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The lipid content of sea squirts is low, namely less than a half percent of the fresh weight. Lipids consist of about seventy percent of saponifiable lipids and of about twenty percent of non-saponifiable lipids. Both types of these lipids, including sterols, can be synthesized from acetate by these animals. Small amounts of C30 sterols were observed only in Microcosmus sulcatus and Halocynthia papillosa, the species with a low content of C27 sterols and a high content of C28 sterols. In addition these species contained considerable higher amounts of sterols with a double bond at the C22 position than Ciona intestinalis and Styela plicata did.  相似文献   

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本文对兰科中9个亚族的分类问题进行了探讨,并发表了5个新亚族:宽距兰亚族Subtrib Yoaniinae、肉药兰亚族Subtrib.Sterosandrinae、紫茎兰亚族Subtrib.Risleyinae、坛花兰亚族Subtrib.A- canthephippiinae和筒瓣兰亚族Subtrib.Anthegoiinae。  相似文献   

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