全文获取类型
收费全文 | 75223篇 |
免费 | 1054篇 |
国内免费 | 843篇 |
专业分类
测绘学 | 1894篇 |
大气科学 | 5242篇 |
地球物理 | 14024篇 |
地质学 | 27228篇 |
海洋学 | 7115篇 |
天文学 | 17764篇 |
综合类 | 245篇 |
自然地理 | 3608篇 |
出版年
2022年 | 543篇 |
2021年 | 912篇 |
2020年 | 1002篇 |
2019年 | 1056篇 |
2018年 | 2271篇 |
2017年 | 2178篇 |
2016年 | 2615篇 |
2015年 | 1403篇 |
2014年 | 2441篇 |
2013年 | 4108篇 |
2012年 | 2626篇 |
2011年 | 3382篇 |
2010年 | 2953篇 |
2009年 | 3776篇 |
2008年 | 3240篇 |
2007年 | 3323篇 |
2006年 | 3104篇 |
2005年 | 2182篇 |
2004年 | 2208篇 |
2003年 | 2069篇 |
2002年 | 2020篇 |
2001年 | 1786篇 |
2000年 | 1673篇 |
1999年 | 1337篇 |
1998年 | 1411篇 |
1997年 | 1297篇 |
1996年 | 1125篇 |
1995年 | 1061篇 |
1994年 | 989篇 |
1993年 | 847篇 |
1992年 | 825篇 |
1991年 | 820篇 |
1990年 | 889篇 |
1989年 | 686篇 |
1988年 | 682篇 |
1987年 | 754篇 |
1986年 | 651篇 |
1985年 | 890篇 |
1984年 | 925篇 |
1983年 | 811篇 |
1982年 | 791篇 |
1981年 | 668篇 |
1980年 | 677篇 |
1979年 | 646篇 |
1978年 | 647篇 |
1977年 | 524篇 |
1976年 | 498篇 |
1975年 | 511篇 |
1974年 | 468篇 |
1973年 | 495篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
S. A. Miller 《Geophysical Journal International》2008,173(1):334-338
Recently reported rain-triggered seismicity from three separate storms occurred exclusively in karst geology. In this paper, I discuss how the hydrogeology of karst controls rain-triggered seismicity by channeling of the watershed after intense rainfall directly into the karst network. Such channeling results in very large increases in hydraulic head, and more importantly, substantially increases the vertical stress acting on the underlying pore-elastic media. Rapid loading upon a pore-elastic media induces seismicity by increasing pore pressure at depth in a manner similar to that observed from reservoir impounding. Using a simple 1-D model of a pore-elastic medium, it is shown that the instantaneous fluid pressure increase at depth is a substantial fraction of the pressure step applied at the boundary, followed by time-dependent pore pressure increases associated with the typical linear diffusion problem. These results have implications for the change in fluid pressure necessary to trigger earthquakes, and leads to the following hypothesis to be tested: Unambiguous rain-triggered seismicity will only occur in karst regions. 相似文献
992.
This tutorial paper presents a simplified view of one of the more recently published multivariatecalibration methods particularly suited to dealing with non-linear data sets.The method is referred toas MARS and stands for multivariate adaptive regression splines.Simple examples are provided toexplain the workings of the method. 相似文献
993.
Naziha Mokadem Younes Hamed Amina Ben Sâad Imed Gargouri 《Arabian Journal of Geosciences》2014,7(5):2071-2079
Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems, heritage and climate. New insights into the characterisation of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. In the phosphate mining area (El Guettar–M’Dilla basin: Southwestern Tunisia), several diseases have been known as cancer, respiratory, allergies, cardiovascular, dental fluorosis, stress, etc. These diseases are directly related with the installation of the industrial sector of the CPG (from 1896) and the deforestation and the ecosystem degradation (fauna and flora). 相似文献
994.
S. H. Derbyshire 《Boundary-Layer Meteorology》1995,75(1-2):1-24
As argued in Part I (Derbyshire, 1995), variability is a key issue in stable boundary layers, and differences in variability between observations and idealized models may imply sytematic biases. Here we discuss how data analysis can be geared to allow for variability and thus consistency with models. Instrumental errors, smoothing methods and vertical discretization are considered. We then show how statistical averaging broadly improves the agreement of heterogeneous results in Part I with the Brost-Wyngaard closure. Recommendations are made for the information needed to analyze apparent differences between homogeneous and heterogeneous stable boundary layers.Part of UK Meteorological Office Atmospheric Processes Research Division 相似文献
995.
Diet restriction induced autophagy: a lysosomal protective system against oxidative- and pollutant-stress and cell injury 总被引:1,自引:0,他引:1
Moore MN 《Marine environmental research》2004,58(2-5):603-607
Nutrient deprivation or dietary restriction (DR) confers protection against ageing and stress in many animals and induced lysosomal autophagy is part of this mechanism. The effects of dietary restriction on the toxicity of copper and the polycyclic aromatic hydrocarbon phenanthrene have been investigated in the common marine mussel Mytilus edulis. The findings show that DR-induced autophagy facilitates the recovery of the digestive gland (i.e., molluscan liver analogue) from cell injury caused by both copper and phenanthrene. It is inferred that DR-induced autophagy and lysosomal proteolysis results in improved cellular "housekeeping" through the more efficient removal of oxidatively and pollutant damaged proteins (e.g., protein carbonyls, protein adducts, etc.) and that this contributes to stress resistance. 相似文献
996.
Regoli F Nigro M Chierici E Cerrano C Schiapparelli S Totti C Bavestrello G 《Marine environmental research》2004,58(2-5):637-640
The role of endosymbiotic diatoms as pro-oxidant stressors in porifera has been investigated in the Antarctic sponge Haliclona dancoi in which the presence of diatoms is influenced by marked seasonal variations during the austral summer. Both chlorophaeopigments and frustules were absent in sponge tissues sampled in early November at the beginning of the summer and increased from the mid of December with slightly shifted temporal trends. The efficiency of antioxidant defenses in the sponge showed a marked response to symbionts with clearly enhanced values corresponding to the peak of diatoms. 相似文献
997.
998.
S. F. Dotsenko 《Physical Oceanography》1998,9(5):323-331
The paper analyses the effect of non-linearity and bottom friction on propagation of tsunami-type surface waves from the abyssal
part of the Black Sea towards the shelf zone. The study relies, on numerical solution of unidimensional non-linear equations
for long waves, using the finite-difference technique. Numerical experiments have been conducted for the bottom profile continental
slope and shelf, with the full wave reflection being prescribed at a 10-m depth contour. It has been shown that the major
role in transforming solitary waves belongs to non-linear topographic factors rather than to dissipation. The reflected wave
has been found to be non-linearly distorted, and wave heights in the Black Sea coastal zone have been found to increase by
many times.
Translated by Vladimir A. Puchkin. 相似文献
999.
W. R. Hartley A. Thiyagarajah M. B. Anderson M. W. Broxson S. E. Major S. I. Zell 《Marine environmental research》1998,46(1-5)
The purpose of this research was to evaluate the Japanese medaka (Oryzias latipes) as an ecotoxicological model for the rapid evaluation of environmental estrogens. A novel short-term (48-h) exposure to 17 β-estradiol is proposed in development of a positive control for disruption of gonadal development. Recently hatched medaka fry (30 fry per dose group) with undifferentiated gonads were exposed to 4.0, 29.4, and 115.6 μg/liter of 17 β-estradiol (acetone carrier) for 48 h in a water bath at 25 °C. The fry were then grown-out in spring water for 2 weeks, killed, and processed for histological evaluation. High lethality was encountered during the grow-out period in the 115.6 μg/liter dose group. Fry in the spring water and acetone (carrier) control groups developed into females or males. Fry exposed to 17 β-estradiol developed primarily into females or had testis-ova. 相似文献
1000.
Normal faults occur in a variety of geodynamic environments, both in areas of subsidence and uplift. Normal faults may have slip rates faster or slower than regional subsidence or uplift rates. The total subsidence may be defined as the sum of the hangingwall subsidence generated by the normal fault and the regional subsidence or uplift rate. Positive total subsidence obviously increases the accommodation space (e.g., passive margins and back-arc basins), in contrast with negative total subsidence (e.g., orogens). Where the hangingwall subsidence rate is faster than the sedimentation rate in cases of both positive and negative total subsidence, the facies and thickness of the syntectonic stratigraphic package may vary from the hangingwall to the footwall. A hangingwall subsidence rate slower than sedimentation rate only results in a larger thickness of the strata growing in the hangingwall, with no facies changes and no morphological step at the surface. The isostatic footwall uplift is also proportional to the amount and density of the sediments filling the half-graben and therefore it should be more significant when the hangingwall subsidence rate is higher than sedimentation rate. 相似文献