全文获取类型
收费全文 | 105篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
地球物理 | 40篇 |
地质学 | 30篇 |
海洋学 | 21篇 |
天文学 | 17篇 |
综合类 | 1篇 |
自然地理 | 3篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2012年 | 1篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有112条查询结果,搜索用时 156 毫秒
61.
Feeding Habits of the Mesopelagic Fish Gonostoma gracile in the Northwestern North Pacific 总被引:1,自引:0,他引:1
The diet of Gonostoma gracile, a numerically abundant mesopelagic fish in the Subtropical Region and the Transition Domain of the northwestern North Pacific,
was examined using 520 specimens collected during June–July 1988, June 1995 and November 1995. The prey included mainly copepods,
ostracods, amphipods and euphausiids. Copepods and ostracods were the most abundant, comprising approximately 70% of the total
diet. There was little evidence of an ontogenetic dietary shift; Pleuromamma copepods were the most abundant prey for all size classes of fish ranging from 19 to 116 mm in standard length. The size
range of prey increased with growth, but all fish sizes examined fed mainly on 1–4 mm long prey. Luminescent copepods and
ostracods were the most abundant prey, suggesting that G. gracile detects its prey visually.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
62.
The determination of rare earth elements (REEs), Th and U in seaweeds of various species and in ambient surface seawater were performed by inductively coupled plasma mass spectrometry. The seaweeds and the seawater samples were collected at 10 different coastal areas of Niigata Prefecture in Japan twice a year (spring and autumn) in 2004 and 2005. Results showed that concentration of REEs in seaweed species from Niigata Prefecture were about 103 times higher than those in seawater, and the enrichment factors of REEs were larger in heavy REE than light REE. A significant concentration difference of REEs, Th and U was found among species even in the same phylum. Undaria pinnatifida had the highest concentration of U. Considering that U. pinnatifida has low concentrations of REEs among typical brown algae, different REEs and U uptake mechanisms are suggested. The concentration of REEs, Th and U did not vary remarkably between sampling points and/or seasons. 相似文献
63.
64.
Song JY Nakayama K Murakami Y Jung SJ Oh MJ Matsuoka S Kawakami H Kitamura S 《Marine pollution bulletin》2008,57(6-12):889-894
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79+/-1.88 x 10(7)leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45+/-0.45 x 10(8)cells/mL. The bacterial numbers of control fish were 4.27+/-3.68 x 10(4)CFU/g, whereas they were 4.58+/-1.63 x 10(5)CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease. 相似文献
65.
66.
基于银因其具有良好的广谱抗茵活性和低毒性而在医学方面有着较为广泛的应用,对银离子(硝酸银)和含银不锈钢的抗茵活性进行了初步研究。实验结果表明,在10^6CFu/mL的初始接种浓度下,银离子对枯草杆菌、大肠杆菌和假单胞茵的最小抑茵质量浓度和最小杀菌质量浓度分别为2,6,8mg/L和2,8,10mg/L。大肠杆菌经8mg/L的银离子处理2h后,有99.9%以上的细菌被破坏。含银不锈钢也表现了较强的抗菌性能。在普通的、银合金和银涂层的sus304不锈钢表面附着的单层生物膜浸泡在PBS溶液中3d后,经CFDA-DAPI双染色和荧光显微镜观察计数获得的假单胞菌的平均存活率为98.0%,38.5%和15.1%。 相似文献
67.
Lithological and geochemical features of platformal carbonates record the signatures of the global climates and the regional environmental settings and also reconstruct the diagenetic history and porosity evolution, which are essential to evaluate the potential of hydrocarbon reservoirs. This study investigates the platformal carbonates of the Oligo‐Miocene Krunji Formation of North East Java Basin, which are potentially significant hydrocarbon reservoirs. The carbonate sequence in a 283 m thick section at Kranji in East Java is subdivided into three lithological units: limestone unit 1, dolostone unit 2, and limestone unit 3, in ascending order. The strontium‐isotope ratios of well‐preserved calcite samples indicate the depositional period from Chattian (late Oligocene) to Burdigalian (early Miocene), which is consistent with ages of the foraminifer assemblages. Unit 1 consists of low‐porosity limestone, in which two horizons of subaerial exposure are recognized by the occurrence of red‐colored matrix and lower δ13C values. Unit 2 consists of dolomitic rock and exhibits coarse‐grained calcitic grains and cross‐stratified structure. Considering that this unit has been subject to dolomitization, the sediment of unit 2 was initially permeable and was likely deposited in a shoal setting. The overlying unit 3 of Aquitanian–Burdigalian age is characterized by a highly granular texture. High porosity and uniformly low δ13C and δ18O values indicate that Unit 3 was subjected to more intense meteoric diagenesis than the Chattian unit 1. This was likely a consequence of the Antarctic ice‐sheet expansion during the Oligocene/Miocene transition, which amplified sea level change. The unit 2 dolomite has high δ13C and δ18O values and a high 87Sr/86Sr ratio which resulted from the reflux of seawater into permeable the sediment body in middle‐late Miocene (Burdigalian Tortonian) following the deposition of unit 3. The porosity and permeability of the Kujung Formation were initially controlled by sedimentological processes, but largely modified by later diagenetic processes. 相似文献
68.
B. C. Prabhakar M. Jayananda Mohamed Shareef T. Kano 《Journal of the Geological Society of India》2009,74(2):171-188
In this paper we document widespread coeval felsic-mafic magma interaction and progressive hybridization near Gurgunta in
the northern part of Eastern Dharwar Craton (EDC) where mafic magma pulses have injected into a 2.5 Ga granite pluton. The
pluton contains voluminous pink porphyritic facies with minor equigranular grey facies. The mafic body shows compositional
variation from diorite to meladiorite with hornblende as the chief mafic mineral with lesser clinopyroxene and biotite. The
observed variation on binary diagrams suggests that granite was evolved by fractional crystallization. Chemical characteristics
such as higher Al2O3 and moderate to high CaO, Mg#, Ni, Cr, Co and V are interpreted by slab-melting. Mafic bodies show lower SiO2, Na2O and K2O; but higher CaO, Mg#, FeO, Cr, Ni and V; higher LREE with moderate to higher HREE which suggest their derivation from mantle.
A major active shear zone has played an important role at the time of synplutonic mafic injection and hybridization process.
Field evidences suggest that the synplutonic mafic body has injected into the crystallizing felsic magma chamber in successive
stages. The first stage injection has resulted in extensive mixing and hybridization due to the liquidus state of resident
felsic magma to which hot mafic magma was injected. However, progressive mixing produced heterogeneity as the xenocrysts started
mechanically dispersed into hybrid magma. The second stage injection, after a time gap, encountered colder and viscous hybrid
magma in the magma chamber, which inhibited free injection. As a consequence, the mafic magma spread into magma chamber as
flows, producing massive mafic bodies. However, with the continued mafic pulses and the heat gradient, the viscosity contrasts
of mafic magma and felsic magma were again lowered resulting in second stage mixing. This episode was followed by mingling
when the granite was almost crystallized, but still viscous enough to accommodate lamellar and ribbon like mafic penetrations
to produce mingling. The successive mixing and mingling processes account for the observed heterogeneity in the granite pluton. 相似文献
69.
The Saga Plain is near Beppu–Shimabara graben, a region of potential active volcanism. In the graben, mantle He, which has a high 3He/4He ratio of 1.1 × 10−5, escapes easily from the underlying subduction zone. In groundwater of the Saga Plain, except in the Shiroishi district, this ratio gradually increased as the dissolved He content increased, to a maximum of 5 × 10−6. In central Shiroishi, however, the ratio reached a minimum of 8.7 × 10−7 with increasing dissolved He content, suggesting that groundwater in central Shiroishi has selectively accumulated radiogenic He, which has a very low ratio of 1 × 10−8, rather than reflecting the regional He, which is rich in mantle He. This can be explained if groundwater in Shiroishi has become mixed with fossil pore water drawn from impermeable marine clay aquitard layers. The withdrawal of pore water has also caused severe land subsidence in central Shiroishi. 相似文献
70.
Influence of microbial photosynthesis on tufa stromatolite formation and ambient water chemistry, SW Japan 总被引:1,自引:0,他引:1
Photosynthetic influences on tufa stromatolite formation and ambient water chemistry were investigated at two well-studied streams depositing tufa in Southwestern Japan (Shirokawa and Shimokuraida). The tufa stromatolites in both streams are composed of fine-grained calcite crystals showing annual lamination, and colonized by a number of filamentous cyanobacteria as well as non-phototrophic bacteria. Microelectrode measurements of pH, O2, and Ca2+ near the stromatolite surface (the diffusive boundary layer; DBL) revealed that the investigated tufa stromatolites are formed by photosynthesis-induced CaCO3 precipitation (PCP): cyanobacterial photosynthesis induces calcite precipitation under light conditions, while respiration of cyanobacteria and non-phototrophic bacteria inhibits precipitation in the dark. The bulk water chemistry at the lower sites of the investigated streams showed the daytime decreases of Ca2+ concentration and alkalinity that was expected for significant influence of PCP, while the other expected change, increased pH, was not observed. In order to examine this discrepancy, a novel approach using semi-in situ microelectrode measurements was applied to perform precise quantitative calculations. The calculation results demonstrated that the observed Ca2+ concentration and alkalinity decreases were caused by PCP, and that the concomitant pH increase was expected to be under the detection level of a conventional pH meter. Although the amount of PCP is supposed to be significantly affected by light intensity, observations in Shimokuraida revealed that the amount of PCP on cloudy day nonetheless accounted for about 80% of that on sunny day. Despite the significant role of PCP for tufa stromatolite formation, PCP accounted for only about 10% of the precipitated calcite in the investigated streams, which indicates that tufa stromatolites, the characteristic deposits in the streams, are responsible for only a small portion of calcite precipitation, and the rest is considered to precipitate inorganically at biofilm-free substrates. 相似文献