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1.
Summary At the present time the autonomous exploration of the sea may be divided into three main fields: airScuba down to 60 m; diving saucers down to 1200 m; bathyscaph down to the greatest depths of the ocean. In the near future, theScuba with special gas mixtures, excluding nitrogen, and the underwater permanent laboratories, will open a new field for biological investigations; progress in metallurgy may also allow diving with engines, without a floating tank, down to 2000 m.The ability of the deep-sea vehicles to stop and remain at a definite depth below the surface needs further research.TheScuba is interesting for investigating the biotopes where the usual devices cannot be used from a surface vessel, for instance in submarine caves. Very special biocoenoses have been found in the totally dark parts of these caves with impoverished stocks and sometimes relict species; the sampling may be perfect both on soft and hard bottoms. With the deep-sea vehicles, investigations may be carried out on the behaviour and distribution of the bottom epifauna. The bathyscaph also allows a general view of the vertical distribution of plankton much better than using plankton samplers, because the plankton nets or pumps are always working on a discontinuous scale. Unfortunately the sampling is much more difficult, especially as far as the plankton is concerned. It is necessary that the engineers pay more attention to the biological devices; very good data have been obtained for temperature, pressure, sound-velocity, etc., but in many instances the biologist diving with a deep-sea vehicle cannot do more than look at the animals and take photographs.  相似文献   

2.
Summary Autoradiographic investigations on the uptake ofl-glutamate andl-aspartate have shown that the amino acids were taken up by neurones as well as by glial cells of cultured human and rat spinal cord. The activity of glutamate and aspartate varied considerably between individual neurones, whereas glial cells showed a more even distribution of the labelled amino acids. Our results suggest that both neurones and glial cells are involved in the uptake of amino acid transmitters.  相似文献   

3.
This paper treats Bernard Bolzano's (1781–1848) investigations into a fundamental problem of geometry: the problem of adequately defining the concepts of line (or curve), surface, solid, and continuum. Bolzano's interest in this problem spanned most of his creative lifetime. In this paper a full discussion is given of the philosophical and mathematical motivation of Bolzano's problem as well as his two solutions to the problem. Bolzano's work on this part of geometry is relevant to the history of modern mathematics, because it forms a prelude to the more recent development of topological dimension theory.  相似文献   

4.
Summary The recent successes in chemotherapy suggest that a solution of the same order should now be possible for cancer. The cause of cancer being still unknown, the therapeutic action aimed at is the creation in the organism of conditions unfavorable for cell multiplication. Certain of the factors essential for cell growth, such as the hydrocarbons, have already been studied in this light. The author has demonstrated the possibility of influencing the high degree of hydration of tumor tissue by the use of substances capable of effecting a homogeneous distribution of the dispersed substances in the aqueous phase. Furthermore, it was proposed to influence the protein repair accompanying cell multiplication by means of substances having an affinity for proteins. This was done to effect a condensation of protein elements before they reach the tumor, thus producing a return to the normal concentration of the free protein fraction, and, at the same time, a decrease in the turn-over of these elements through the tumor. Electrophoretic measurements made with theTiselius apparatus have made it possible to follow protein affinity and to suggest the synthesis of compounds containing quinone and imine groups which may prove valuable in future investigations along these lines.  相似文献   

5.
Summary The inhibition of cardiac myofibrillar ATPase activity by EDTA can be completely reversed by Ca++ under certain experimental conditions. This shows that there is no fundamental difference between the reaction of cardiac myofibrillar ATPase and the tension development of glycerinated cardiac fibres, as was supposed byBriggs andHannah on account of the results ofParker andBerger.  相似文献   

6.
We analyse some aspects of Einstein's research on the light quantum between 1905 and 1916. The central subject of our paper is the discussion of the possible relationship between a little known paper of his on photochemical equivalence and his well-known 1916 derivation of Planck's formula, indicating the possibility of a deep continuity between these, at first sight, little correlated, investigations. We also re-examine another chapter of Einstein's research on the behavior of radiation: momentum fluctuations (MF). The recurring use he made of his formula for MF has already been analysed in the literature. We emphasize that although through shifts of meaning, it establishes a close relationship between two distant stages of his research. We indicate where one might discover Einstein's first dissatisfaction with the probabilistic character of quantum physics, in relation to some aspects of his works of 1916.  相似文献   

7.
Summary Tetrahymena size distribution during the cell cycle was analyzed by means of radioautography with the aid of a sonic-digitizer, and a computer. The study demonstrates that as the organism ages and passes through the various cell cycle phases the volume distribution of the organisms in each phase remains lognormal.Acknowledgments. This work was supported by a research grant from Gtiftung Volkswagenwerk No. 112273 toA. Ron. The authors wish to acknowledge the technical help of Mrs.O. Horovitz and MissS. Urieli, as well as the expert photomicrography of Mrs.E. Salomon.  相似文献   

8.
Summary A survey is given of recent work on physical aspects of sensory processes. The reasoning which leads to the generally recognized view that one rod of the retina is excited by only one quantum of light is given in par. II. In par. IIIa summary is given of the papers byHecht andVan der Velden on the number of rods which must be struck in order to obtaina sensation of light. Par. III describes the role of the quantum character of light at higher intensities (de Vries), where it sets a limit to intensity discrimination and visual acuity. The influence of Brownian movement on the process of hearing is discussed in par. VI. It is found that the Brownian movement of the inner ear is close to the threshold actually observed (de Vries), whereas the Brownian motion of the air at the eardrum (seeSivian andWhite) is below the audible threshold. The role of the Brownian movementin the sense cells is described in par. VII; the results are used for an analysis of the mechanism of hearing (see alsode Vries); evidence is obtained that electric voltages are generated in the tectorial membrane (the well-known cochlear microphonics) and that they play an important part in the mechanism of energy transfer to the sense cells (similar voltages were also derived from the cupolæ in the lateral lines of fishes by the present author). Finally some physical arguments are sumarized againstYeagley's theory of bird navigation.  相似文献   

9.
Summary Boltzmann's ergodic hypothesis is usually understood as the assumption that the trajectory of an isolated mechanical system runs through all states compatible with the total energy of the system. This understanding of Boltzmann stems from the Ehrenfests' review of the foundations of statistical mechanics in 1911. If Boltzmann's work is read with any attention, it becomes impossible to ascribe to him the claim that one single trajectory would fill the whole of state space. He admitted a continuous number of different possible mechanical trajectories. Ergodicity was formulated as the condition that only one integral of motion, the total energy, is preserved in time. The two reasons for this are external disturbing forces and collisions within the system. Boltzmann found it difficult to ascribe ergodic behavior to a single system where the theoretical dependence on initial conditions, though never observed, has to be admitted as possible. To circumvent the dependence, he invented the concept of a microcanonical ensemble.  相似文献   

10.
Summary Rats fed an essential fatty acid deficient diet (EFAD) showed a statistically significant decrease in the thickness and ultrastructural asymmetry of the luminal membrane and cytoplasmic vesicles of transitional epithelium of the urinary tract, due to a marked thinning of the peculiar thick luminal leaflet. These changes were reversed by adding EFA to the diet. This indicates that the unusual EM appearance of urothelial membrane depends on its content in EFA.Acknowledgment is due to Mrs.M. G. Iwakawa andN. T. Benítez for technical help and Mr.J. Hiza for animal care.D. Lis andA. Eynard are research fellows of Consejo Nacional de Investigaciones Científicas y Técnicas. Work supported in part by CONICET, Argentina.  相似文献   

11.
Summary The chloride electrochemical potential difference between the inside of cells ofNitella translucens and some external solutions, where Cl has been progressively replaced by benzenesulphonate, has been measured by means of Ag-AgCl electrodes. It appears that benzenesulphonate moves into the cell by an electrogenic pump and that the uptake of Cl byNitella is not in contradiction with a carrier hypothesis.

This work was supported by grants from the F.N.R.S. and was carried out in the Biophysics Section of the Edinburgh University. We are indebted to Dr. E. J.Williams and Dr.Hogg for having sponsored this research and kindly provided the material.  相似文献   

12.
Summary A survey is given of some recent progress, particularly in the author's own laboratory, of methods for the separation of macromolecules and particles of biological origin, as viruses, bacteriophage, microsomes, cell fragments, bacteria and whole cells. Special attention is given to recent developments in zone electrophoresis, protein chromatography, gel filtration and the new partition methods for separation of particles and macromolecules (Albertsson). A number of examples are given to illustrate the various applications. Special emphasis is laid upon the new possibilities for biochemical-genetic studies by application of high-resolution separation methods, and the significance of particle separation methods as applied to fragments of biological structures in providing a tool for structure investigations on a macromolecular level—a field which also should be of considerable interest from a chemical point of view.

DrittePaul-Karrer-Vorlesung gehalten an der Universität Zürich am 5. Juli 1961.  相似文献   

13.
Summary The study of the distribution of Cd, Zn and Cu in homogenates of mussels has shown that Zn and Cu are principally associated with high mol. wt. proteins. The same distribution is observed for Cd in untreated mussels, but in Cd chronically intoxicated animals, the metal is principally bound to low mol. wt. proteins synthesized in response to the uptake of the cation and similar to metallothioneins of vertebrates.This research was carried out in participation in the Belgian National Research and Development Program on the Environment-Water-Sea Project-Office of the Prime Minister-Interministerial Commission for Science Policy and Programmation.I am grateful to Prof.A. Disteche and Dr.Ch. Gerday for theiradvice throughout this work. I thankR. Biondo andN. Gerardin for excellent technical assistance.  相似文献   

14.
Summary For the first time, heterotrophic accumulation of dissolved carbon by a soft-bodied marine invertebrate under in situ conditions has been demonstrated. The polychaete wormSchizobranchia insignis Bush concentrated14C-labelled dissolved carbon (DC) exudated by the large brown alga,Macrocystis integrifolia Bory, 14 times over the killed controls. Our evidence suggests that algal exudate may be a significant nutritional supplement to some invertebrates cohabitating withM. integrifolia.This study was supported by Operating Grant No. A6966 to PVF from the National Research Council of Canada.We are grateful to MrG. F. Cota, Dalhousie University, Halifax, for his contributions to the field experiments.  相似文献   

15.
Summary The androgen insensitive, genetically male rat pseudohermaphrodite displays neither masculine or feminine sexual behavior when primed with the appropriate sex hormones. although in the absence of androgen imprinting the animal develops anatomically as female, our results suggest that feminine differentiation of the brain requires active imprinting by perinatal hormone(s), possibly adrenal progesterone.The research was partially supported by a grant from the Rockefeller Foundation.A. S. Goldman is a U.S.P.H.S. Career Development Awardee (No. HD-13,628).  相似文献   

16.
Summary The air stores carried by a number of aquatic insects have: a) a hydrostatic function (Brocher, Oortwijn-Botjes, Thorpe, andCrisp); b) the function of an oxygen store (Ege, de Ruiter et al.) and c) the function of a physical gill (Strauss-Durckheim, Ege, etc.). The fact that oxygen is taken up from water with the aid of an air bubble was demonstrated forNotonecta by comparing the life time of insects with and without physical gill (while replenishing the oxygen store from the air was prevented) byEge, and forCorixa byPopham, whileVlasblom determined the oxygen uptake from water with and without air bubble forNotonecta, Naucoris, Corixa, Sigara andNepa. Nepa andSigara can take up considerable quantities of oxygen by cutaneous respiration.During the summer, the gill function of the air store ofNotonecta andNaucoris is of importance only when a water current passes along the animal, caused by ventilation movements of the legs (de Ruiter et al.). At low temperatures, however, the metabolic rate is so low that in many instances the physical gill provides the oxygen required without ventilation movements.An apparatus for the simultaneous determination of oxygen uptake from air and water (Wolvekamp andVlasblom) gave results that provided a means of evaluating the importance of the physical gill function.In some cases, the air store, although in direct contact with the water, does not need to be replenished. InAphelocheirus andElmis, the negative pressure in the bubble, caused by oxygen consumption and the diffusing out of part of the nitrogen, is compensated for by the mechanical resistance of a feltwork of thin hairs and the surface tension of the boundary layer of the water (Thorpe andCrisp). In the African beetle,Potamodytes, the unprotected air bubble is permanent because the strong river currents produce a lowered pressure around the animal according toBernoulli's principle (Stride).  相似文献   

17.
Summary Following 1 h exposure, the level of phospholipase A2 penetration into the axoplasm of the squid giant axon was 107 to 350% of that in the external media; corresponding values for phospholipase C were 18 to 31%. Phospholipases can therefore be used to study phospholipid function in axons since they can penetrate through connective tissue and Schwann cell to reach the axolemma.I thank Dr.Toshio Narahashi for allowing me to use his laboratory facilities at the Marine Biological Laboratory, Woods Hole, Mass. for the dissection of squid axons. Expert technical assistance in these studies were provided by Mr.Steven Trudel and Mr.Stuart Owen Rosenberg. This work was supported in part by a grant from the University of Connecticut Research Foundation.  相似文献   

18.
Summary The afferent impulses from the ampullae ofLorenzini ofScyllium show, both in the intact animal and in the isolated preparation, a steady discharge at constant temperature with a frequency reaching a maximum at an average of 20° and decreasing continuously at higher and lower temperatures. The discharge stops between 5° and 30° on the average. Rapid cooling causes a temporary rise in frequency, while rapid warming causes a temporary drop in frequency. While the ampullae are not sensitive to a mechanical stimulus, they react definitely to a change in temperature of 0.05°C. The ampullae thus behave like the cold receptors of the homoiotherms.  相似文献   

19.
Résumé Les petits lymphocytes du sang, après avoir été mis en contact pendant plusieurs jours avec les cellules lymphoïdes d'une lignée autochthone, peuvent tuer les cellules de cette lignée et d'autres lignées. Ces investigations peuvent apporter de nouvelles données sur l'opération de contrôle immunologique.

We are grateful to Dr.N. R. Ling for his help and guidance.D. A. Hardy gratefully acknowledges financial support from the Medical Research Council and the John Squire Fund.  相似文献   

20.
Summary The histochemical localization of some enzymatic activities is surveyed in the optic tectum of vertebrates from cyclostomes to birds. These data are compared with results arising from ultrastructural and experimental works in order to outline some possible connections between enzyme localization and functional organization of the optic tectum. The most interesting result derives from acetylcholinesterase which, in the majority of vertebrate species, is localized in tectal layers in which visual and other sensitive afferents discharge. Such a situation, together with some experimental and developmental results, suggests that cholinergic mechanisms play an important role in the function of the optic tectum and that these mechanisms are worthy of further and more detailed investigations.Acknowledgments. The author is grateful to Prof.S. Leghissa, Dr. F. Ciani andDr. L. Villani for the permission to use the photographs 8–11 of the present paper.  相似文献   

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