共查询到20条相似文献，搜索用时 140 毫秒
1.
Georg Ribi 《Aquatic Sciences - Research Across Boundaries》1992,54(1):85-90
Larvae of perch (Perca fluviatilis L.) reared in tanks for 27 days survived better in lake water to which 2% of artificial sea water had been added (46.6% average survival rate) than in lake water only (13.5% survival). One week after hatching, over 90% of the larvae had their guts filled in all tanks. During the following week the populations divided into floaters (fish with an inflated swimbladder) and sinkers (fish apparently lacking a functional swim-bladder). Although they continued feeding, sinkers remained smaller than floaters and most of them died. 相似文献
2.
¶rt;m uu nau mu m a nu a¶rt;u ¶rt; D-amu u. a¶rt; m nu u u. u¶rt;a a a mu nma u nma mu m (20 ¶rt; 150 ). 相似文献
3.
Prakash Chandra Singh 《Pure and Applied Geophysics》1972,98(1):87-101
Summary Dispersion in Rayleigh waves is discussed for semi-infinite media with =
1(1 ± cos s z) and =
1(1 ± cosh s z), being the rigidity of the medium. A few workers tried with the above Fourier type of model but failed to find the dispersive nature. Because they neglected s due to the complexity of the calculation they arrived at a non dispersive frequency equation. This difficulty is removed in this paper and a dispersive frequency equation is obtained which shows both direct and inverse dispersion. The second model leads to non-convergent solution forz but shows many interesting results which are also discussed. 相似文献
4.
u¶rt;m n uu ¶rt;u m n u ma n¶rt;aa, nu m¶rt;u u ¶rt;uau. n nuu uu ¶rt;u m n ¶rt;a¶rt; nu NoNo VI, VII. u au u n m a
(x, H), ¶rt;auu an¶rt;u ¶rt;u m ¶rt; m¶rt; nu, u mua m nuu
(H), aamuu an¶rt;u m a mua ¶rt;¶rt; uu ¶rt;uua u a. u a ¶rt;u m
(x, H) amm ¶rt;uuu (u) a m¶rt; nu. m¶rt; u, auuu aau, om aamuam muau an¶rt;u ¶rt;u m, uu , n m u m nu aamuu a nmu, am ma a¶rt;am aa uu ¶rt;u m. aa u a¶rt;u n nu NoNo VI u VII u umuu ¶rt;a. mua m nu
(H) num m ¶rt;u amu aua u anam um, ¶rt;a amu ¶rt;aua u ¶rt;- nma (nu No VII). ma ¶rt; ¶rt; aua, maa numa nm m u numa nm ma¶rt;um, a unaa nuu umnmauu a¶rt;uu ¶rt;uau amu aua. 相似文献
5.
¶rt;m ¶rt; uuauu uum auu uu, a¶rt;a a nmunmuaa, ¶rt; n uu u. aa, m u u ¶rt;um nmu, uu n¶rt; m nm, u aaaa u aa m nmua. 相似文献
6.
Libuše Ruprechtová Klára Mrázová Jaroslav Fiedler Reviewer A. Zátopek 《Studia Geophysica et Geodaetica》1984,28(3):286-293
Summary The calculation procedures for determining epicentre parameters of weak near shocks with foci in Poland are discussed and tested for explosions with known epicentres.
m m¶rt; ¶rt; n¶rt;u num a uu m num nmua n auauu, u mu a mumuu u, n muu ¶rt;au uu mau. au mam nam (a. 4) nu nuuu na 71 u m ¶rt;u n¶rt; ¶rt; a auu ¶rt;a [11].相似文献
7.
Fundamental-mode Rayleigh wave attenuation data for stable and tectonically active regions of North America, South America, and India are inverted to obtain several frequency-independent and frequency-dependentQ
models. Because of trade-offs between the effect of depth distribution and frequency-dependence ofQ
on surface wave attenuation there are many diverse models which will satisfy the fundamental-mode data. Higher-mode data, such as 1-Hz Lg can, however, constrain the range of possible models, at least in the upper crust. By using synthetic Lg seismograms to compute expected Lg attenuation coefficients for various models we obtained frequency-dependentQ
models for three stable and three tectonically active regions, after making assumptions concerning the nature of the variation ofQ
with frequency.In stable regions, ifQ
varies as , where is a constant, models in which =0.5, 0.5, and 0.75 satisfy fundamental-mode Rayleigh and 1-Hz Lg data for eastern North America, eastern South America, and the Indian Shield, respectively. IfQ
is assumed to be independent of frequency (=0.0) for periods of 3 s and greater, and is allowed to increase from 0.0 at 3 s to a maximum value at 1 s, then that maximum value for is about 0.7, 0.6, and 0.9, respectively, for eastern North America, eastern South America, and the Indian Shield. TheQ models obtained under each of the above-mentioned two assumptions differ substantially from one another for each region, a result which indicates the importance of obtaining high-quality higher-mode attenuation data over a broad range of periods.Tectonically active regions require a much lower degree of frequency dependence to explain both observed fundamental-mode and observed Lg data. Optimum values of for western North America and western South America are 0.0 if is constant (Q
is independent of frequency), but uncertainty in the Lg attenuation data allows to be as high as about 0.3 for western North America and 0.2 for western South America. In the Himalaya, the optimum value of is about 0.2, but it could range between 0.0 and 0.5. Frequency-independent models (=0.0) for these regions yield minimumQ
values in the upper mantle of about 40, 70, and 40 for western North America, western South America, and the Himalaya, respectively.In order to be compatible with the frequency dependence ofQ observed in body-wave studies,Q
in stable regions must be frequency-dependent to much greater depths than those which can be studied using the surface wave data available for this study, andQ
in tectonically active regions must become frequency-dependent at upper mantle or lower crustal depths.On leave from the Department of Geophysics, Yunnan University, Kunming Yunnan, People's Republic of China 相似文献
8.
František Jiříček Pavel Tříska O. A. Maltseva E. E. Titova T. A. Yakhnina Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1986,30(4):404-410
Summary The occurrence zone of the VLF chorus in the upper ionosphere appears at L-shells lower than plasmapause position Lpp; with increasing geomagnetic activity the spatial dimension of the zone diminishes, its upper boundary being shifted in correspondence with the plasmapause position, the lower remaining practically without change(L=2.0÷2.5). Calculations of propagation paths have shown that the similarity of the VLF chorus spectrum at different upper-ionospheric latitudes as well as the large spatial dimension of the zone of observation can be explained as special features in the propagation of VLF waves from an equatorial source, starting in the vicinity of the plasmapause with different initial normal angles.
a umauu u ana amu L-, u Lpp (Lpp — nu nana); uu aum amumu nmam a am, nu aua am mmmuu uu nu nana, a u mam namuu u(L=2.0÷2.5). am mamu naam, m n¶rt;u nm a au uma u, ma a nmam ama a¶rt;u, m m mu anmau m amua umua, an amu nana, uu au au.相似文献
9.
u uuuuaumau uu u m, ¶rt;u a mumau nmu a u nmu mau u nmmu. au n¶rt; nuau ¶rt;mam u u m. nua m¶rt; m u m¶rt;a aau (1960) ¶rt; uu . 相似文献
10.
Karel Prikner Vladimír Vagner Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1988,32(1):84-100
Summary The method of numerical modelling of ionospheric filtration of the Fourier components of a signal from the frequency range of Pc1 micropulsations is employed in the spectral analysis (frequency f, angle of incidence ) of the relative characteristic of the amplitude and energy reflectivity of the ionospheric layer with respect to ordinary Alfvén modes incident in the meridional plane. The results are presented for four different models characterizing the midlatitude day- and night-time ionosphere under low and high solar activity. The results indicate the specificity of filtration of ordinary Alfvén waves. It is proved that the lower region of the modelled ionosphere, as part of the midlatitude ionospheric wave guide (in particular the F2 layer), behaves like an Alfvén resonator in the given spectral range.
m¶rt; u ¶rt;uau u umauu -mau uaa u amm ¶rt;uanaa unau 1 n¶rtum nma aau (amma f, a¶rt;u ) mum anum¶rt; u mu maamu u ¶rt; ¶rt; a, a¶rt;au a u u¶rt;ua nmu. mam n¶rt;aam ¶rt; m a ¶rt; ¶rt;um m ¶rt; u u nu u u nu amumu. aam nuum umauu a. naa, m ua am ¶rt;ua u (a am F2-u ¶rt;um ¶rt;a) ¶rt;m nma ¶rt;uana a am a.相似文献
11.
Summary One alternative of solving the problem of eliminating the effect of external masses, generating the constant part of the tidal field, from the perturbing potential is presented. The solution is founded on a new definition of the normal gravity field which contains this part of the tidal field. It is proved that two material circles in the plane of the Earth's equator, whose radii are approximately equal to the mean distances of the Moon and Sun from the Earth, can be considered as the source of this field. The new normal gravity field is first derived in the spherical approximation, which enables one to prove simply that the value of the normal gravity potential on the reference surface does not change, and that the change in the definition of the heights is insignificant. The normal gravity field for the equipotential ellipsoid is derived in the same way according to [1].
¶rt;mam ¶rt;a amamua u ¶rt;umua n uu uu u a, au nm am nuu n, u a nmuaa. u a a n¶rt;uu a n u mmu, m m am nuu n aam. aam, m am umua m n umam a ¶rt; m nmu ama, a¶rt;u m nuuum a ¶rt;u amu u a m u. ¶rt; ¶rt; a n u mmu u nuuuu, m nm nm ¶rt;aam, m au a nmuaa u mmu a nmu m u m uu n¶rt;u m aum. ¶rt;ua n (. [1]) ¶rt; a n u mmu ¶rt; unu¶rt;a.相似文献
12.
Marcela Laštovičková Karel Svoboda Рецензенm A. Janáčková 《Studia Geophysica et Geodaetica》1986,30(2):211-213
au aa ¶rt;a, nuau uuu ma n¶rt; u m muu uu, n¶rt; m¶rt;a nm (). u a m u ¶rt; uuu ma u muuu uuau.
Summary Analysis of the data set describing the chemical composition of the rocks and their electrical parameters was performed by the principal component method. Some relations between chemical composition and electrical parameters were established.相似文献
13.
Summary The convection in a rapidly rotating, electrically conducting, horizontal fluid layer, non-constantly stratified and penetrated by an inhomogeneous magnetic field, is studied. The convection is investigated for various ratios of the thickness of the stable and unstable stratified part of the layer. The thermal model of the layer, as well as the analysis of the results have been treated with regard to the physical conditions in the liquid core of the Earth.
am u¶rt;m u m aa mn¶rt; u¶rt;uma nm mamuuau, nua ¶rt;¶rt; aum n. u u¶rt;m ¶rt; a mu m u mu u mu mamuuuao amu . ua ¶rt; , a u aau mam, n¶rt;a anm uuu u u¶rt; ¶rt; u.相似文献
14.
n¶rt;m mu ¶rt; mu uau aumma. mu aum u mu u m u mu auauu m¶rt;a. u¶rt;m u naam nm nmmuna uau aumma. 相似文献
15.
Summary The propagator matrix is expressed in terms of cross-products of spherical Bessel functions and their derivatives. A fast computational algorithm is suggested. The matrix form of the variational principle with the boundary term is derived.
u nu u u u, n¶rt; u¶rt; nu¶rt;u uu u u u nuo¶rt;. ¶rt; au u . ¶rt; u uau nuuna u .相似文献
16.
Summary The paper deals with the general theory of equivalent projection. By specifying the results derived, special cases may be treated. Examples of methods are described which enable free functions to be found in a general solution. A detailed procedure of solving the problem with a numerical example is given, taking into account the optimization according to the global criterton, established for extreme angular distortion.
Dedicated to Professor Frantiek Fiala on the Centenary of his Birthday 相似文献
aamuam a mu auu nu; ¶rt;am m am au. nu m¶rt;, nu amu ¶rt; uu uu. umam nmuauau n aamumu au, ma ¶rt; aua uau , u nuam n¶rt; m¶rt; u u nu.
Dedicated to Professor Frantiek Fiala on the Centenary of his Birthday 相似文献
17.
Miloslav Burda Vincenc Vyskočil Miloš Hübner Reviewer M. Bielik 《Studia Geophysica et Geodaetica》1988,32(1):54-61
Summary Problems of occurrence of density inhomogeneities in the upper mantle are discussed and their gravitational effects in the region of Central Europe are investigated. Attention is namely devoted to the density contrast between the asthenosphere and the lower lithosphere, and its possible dependence on depth.
¶rt;am n nu nmm ¶rt;¶rt;m amuu u uaumau ¶rt;mu a mumuu ¶rt; n. uau ¶rt;m n¶rt; nmm mam ¶rt; am u um u auumu mu aau.相似文献
18.
Summary On the basis of the 1966–73 data, the effect of the difference between pro- and anti-sectors of the IMF is found to be negligible in the winter midlatitude (Central Europe) ionosphere contrary to the dominant effect of this difference in the high-latitude ionosphere found earlier.
a ¶rt;a a 1966–73. u¶rt;m u m amu ¶rt; pro- u anti- mau . na a u ¶rt;um (¶rt; na) u, , a naa a, naum um u.相似文献
19.
aamuam mam uu mn nma ma-au a. a¶rt; uua¶rt;uma mnam, uuma mnn¶rt;mu u mn nma m ¶rt;uamau au uu uma, n¶rt; m n¶rt; mn nm nu¶rt; a. 2. a u au Q=1,99 u 2,06×10–6 /2 am ¶rt;au mu n ua amu, ma mu (2,5×10–6 a/2 ) aum nam mm ¶rt;uana. um mm am na m¶rt;, ¶rt;¶rt; nu¶rt;m am mam. 相似文献
20.
¶rt;m n¶rt;u nu nm n m . m¶rt; n¶rt;am nuuu am uma au muna (6) u (10). amua aumnu m m nn unam u u, m nmu ama mm (u. 2). uu nu nm ¶rt;u am mu n¶rt; uua 15mu anau u mu u nn uua mu anau. u unauu m nn ¶rt;u am mu n¶rt; uua ¶rt; 21 anau.
Dedicated to 90th Birthday of Professor Frantiek Fiala 相似文献
Dedicated to 90th Birthday of Professor Frantiek Fiala 相似文献