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201.
R型聚类分析在区域化探元素分组中的作用探讨 总被引:1,自引:0,他引:1
在处理化探数据方面,R型聚类分析是应用较为广泛的一种数理统计方法。随着研究的深入发现,R型聚类分析的结果并非总是对元素分组起到积极有效的作用。这里对大石寨地区的二叠纪地层、白垩纪地层、黑云母花岗岩以及研究区全区进行39种元素R型聚类分析,得到地层、岩体以及全区的元素组合,但是分组的结果表明,通过R型聚类分析得到的各元素组合均不能明确反映地层、岩体以及全区的地质特征,因此对于R型聚类分析的使用需谨慎。 相似文献
202.
203.
A galaxy that is a good candidate for polar-ring galaxies has been detected in the Hubble Ultra Deep Field (HUDF). The galaxy HUDF 1619 (V ≈ 25 m , z ~ 1) is the most distant object of this type known to date. A large-scale structure crosses the highly warped disk of the main galaxy seen almost edge-on at an angle of about 70°. The luminosity of this structure (the possible polar ring) reaches ~1/3 of the luminosity of the central galaxy. A strong absorption lane is seen in the region where this structure is projected onto the disk of the central object. There are two galaxies of comparable luminosity adjacent to HUDF 1619 (in projection). One of them may be the donor galaxy the interaction with which gave rise to the ring structure. 相似文献
204.
通过传统的TCBS培养基平板计数法、16SrDNA—RFLP(16SrRNA基因的限制性酶切图谱多样性分析)及16SrDNA序列分析等方法对深圳海域水体和九龙江口沉积物中弧菌数量分布进行研究.结果表明TCBS菌群数中弧菌所占的比例因不同采样地点、不同季节而呈现较大差异.在深圳西海域及九龙江口上游盐度较低(盐度〈11)的区域,TCBS菌群中弧菌所占的比例为0,TCBS菌群数与弧菌总数不相关;在河口下游盐度相对较高的区域,弧茵占TCBS菌群数的6.0%~92.0%,TCBS菌群数与弧茵总数不相关或相关性不大;高盐度的海水区域弧菌占TCBS菌群数的37.O%~100.0%,TCBS菌群数与弧菌数量显著相关(P〈0.05).因此环境监测过程中利用TCBS培养基检测海洋弧菌数量时,应该通过分子鉴定或生理生化鉴定方法进行验证,以保证数据的科学性. 相似文献
205.
A. P. Mahtessian 《Astrophysics》2007,50(4):440-450
The effect of observational selection on the relationship between the characteristics of groups of galaxies and their distances
is discussed in this paper. For our groups the dependence of the pairwise distance between the members on the distance of
the group is just that. For the groups of Geller and Huchra, on the other hand, the analogous dependence is distorted by the
effect of their selection criteria for groups of galaxies. The average dispersion of the radial velocities of the galaxies
for our groups is less than half that for the groups of Geller and Huchra, while the mass-to-luminosity ratio is smaller,
on the average, by more than an order of magnitude in our case. Geller-Huchra groups with mass-to-luminosity ratios greater
than 1000 are most likely unreal.
__________
Translated from Astrofizika, Vol. 50, No. 4, pp. 535–546 (November 2007). 相似文献
206.
Results are presented from a spectral, photometric, and morphological study of two compact groups of compact galaxies (CGCG)
from Shahbazian’s list. The observations were made on the 1.5-m ESO telescope and the 2.6-m telescope at the Byurakan Astrophysical
Observatory (BAO) during 1999–2000. These data are compared with data for the Shahbazian compact group 4. A high spatial density
of galaxies, ranging from 10000 to 100000 galaxies per Mpc3, is observed in all the groups that were studied. The discovery of a Seyfert Sy1 galaxy in the Shahbazian 355 compact group
is especially noteworthy. The direct photographs of the CGCGs that were studied contain no signs of merging or tidal interactions
among the members of these groups. This suggests that the galaxies in these dense systems have a common origin.
__________
Translated from Astrofizika, Vol. 50, No. 3, pp. 347–353 (August 2007). 相似文献
207.
Sunita Nair 《Journal of Astrophysics and Astronomy》2002,23(1-2):115-118
The recently discovered gravitationally lensed system CLASS B1359 +154 appears to have six detectable images of a single background
source at a redshift of 3.235. A group of galaxies acts as the lens, at a redshift of ∼ 1. The present work identifies two
distinct, physically plausible image configurations, a 7-image one and a 9-image one. Mass models are constructed corresponding
to realizations of these two configurations. Both models call for, in addition to non-singular galaxy-type lenses, a larger
scale mass component that resembles the extended dark matter distributions seen in relatively low-redshift galaxy groups.
It is presently observationally impossible to study the extended X-ray emission from a group at such a high redshift, hence
lensing studies are of some interest. A lensed system with a high image multiplicity does not necessarily admit of a unique
lensing interpretation; discrimination is possible with additional observable details (e.g., the image parities, which are
uncommon among even the simpler systems). 相似文献
208.
We present a study focusing on the nature of compact groups through the study of their elliptical galaxies. We determine central
velocity dispersions (σo) for 18 bright elliptical galaxies located in the core of Hickson compact groups and a control sample of 12 brightbona fide ellipticals located in the field or very loose groups. Several tests are carried out to avoid systematic effects in σ measurements.
We use these velocity dispersions to compare the position of 11 compact group galaxies in the Fundamental Plane to that of
a large and homogeneous sample of elliptical galaxies (Burstein et al., 1987).We find that little or no significant difference
exists, as far as the Fundamental Plane is concerned, between ellipticals in compact groups and their counterparts in other
environments.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
209.
张志让 《成都信息工程学院学报》1988,(2)
本文通过对D-子群(Perfect Subgroup)的研究,证明群G为超限下Abe1群的充分必要条件是G无非平凡的D-子群。 相似文献
210.
We used a sample of 20 poor groups of galaxies to study the low mass tail of the relationships among the X-ray temperature
T, the X-ray luminosity Lx and the optical velocity dispersion σ. We obtained redshifts for the fainter members of these groups. We find that X-ray
bright groups have more members and higher velocity dispersions on average. Using the fainter group members and MonteCarlo
tests, we define the number of group members required to calculate a robust velocity dispersion. There is a tendency to underestimate
the group velocity dispersion for samples of fewer than∼ 10 members that introduces systematic errors in the slope of the
relationships among Lx, T, and σ. A comparison with the data of Ponman and Mahdavi shows that our improved velocity dispersions provide better constraints
on the relationship between the kinematics of the hot gas and galaxies in these common environments.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献