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994.
Marijan Herak Ivo Allegretti Davorka Herak Krešimir Kuk Vlado Kuk Krešimir Marić Snježana Markušić Josip Stipčević 《Bulletin of Earthquake Engineering》2010,8(3):483-499
Horizontal-to-vertical spectral ratios (HVSR) of ambient vibrations measured in the ancient town of Ston (Croatia) on 99 locations, are shown to be well matched to the theoretical ones computed for body-waves as well as for the surface waves. This match is poorer for sites on the slopes of nearby hills. The ratios of measured peak horizontal ground acceleration during the damaging earthquake in 1996 (M L = 6.0) and the ones obtained using empirical attenuation laws is approximately equal to the mapped value of the dynamic amplification factor determined on the basis of observed HVSR in the vicinity of the accelerometric station. The HVSR of the accelerogram is very similar to the HVSR of the ambient noise. The damage to the building stock in the old town centre caused by the earthquake series of 1996 is closely related to the estimated soil amplification and its fundamental frequency. More measurements in buildings are needed to arrive at confident conclusions about possible soil-structure resonance. 相似文献
995.
Sedat İnan Kadriye Ertekin Cemil Seyis Şakir Şimşek Furkan Kulak Aynur Dikbaş Onur Tan Semih Ergintav Rahşan Çakmak Ahmet Yörük Muhiddin Çergel Hakan Yakan Hüseyin Karakuş Ruhi Saatçilar Zafer Akçiğ Yıldız İravul Bekir Tüzel 《Acta Geophysica》2010,58(5):767-813
Warm and hot spring water as well as soil gas radon release patterns have been monitored in the Aegean Extensional Province of Western Turkey, alongside regional seismic events, providing a multi-disciplinary approach. In the study period of 20 months, seven moderate earthquakes with M L between 4.0 and 4.7 occurred in this seismically very active region; two earthquakes with magnitude 5.0 also occurred near the study area. Seismic monitoring showed no foreshock activity. By contrast, hydro-geochemical anomalies were found prior to these seismic events, each lasting for weeks. The anomalies occurred foremost in conjunction with dip-slip events and seem to support the dilatancy and water diffusion hypothesis. Increased soil gas radon release was recorded before earthquakes associated with strike-slip faults, but no soil radon anomalies were seen before earthquakes associated with dip-slip faults. Geochemical anomalies were also noticeably absent at some springs throughout the postulated deformation zones of impending earthquakes. The reason for this discrepancy might be due to stress/strain anisotropies. 相似文献
996.
Determination of focal depth by two waveformbased methods: A case study for the 2008Panzhihua earthquake
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With the 2008 MS6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches: (1) using the depth phase sPL and (2) using full waveform inversion of local and teleseismic data. We also show that focal depths can be well constrained using the depth phase sPL with single broadband seismic station. Our study indicates that the main shock is located at a depth of 11 km, much shallower than those from other studies, confirming that the earthquake occurs in upper crust. Aftershocks are located in the depth range of 11-16 km, which is consistent with a ruptured near vertical fault whose width is about 10 km, as expected for an MS6.1 earthquake. 相似文献
997.
Geochemical Atlas of Slovakia and examples of its applications to environmental problems 总被引:2,自引:0,他引:2
S. Rapant D. Bodiš K. Vrana V. Cvečková J. Kordík K. Krčmová I. Slaninka 《Environmental Geology》2009,57(1):99-110
Results of comprehensive geochemical mapping and thematic studies of the Slovak territory (rocks, soils, stream sediments,
groundwaters, biomass, and radioactivity) in the first half of the 1990s led to several new research programmes in Slovakia,
within the frame of which new methodologies for geochemical data evaluation and map visualization were elaborated. This study
describes the application and elaboration of data from the Geochemical Atlas of the Slovak Republic at national and regional
levels. Based on the index of environmental risk (IER = ΣPEC/PNEC), the level of contamination for the geological component of the environment in Slovakia was evaluated. Approximately
10.5% of Slovakia’s territory was characterized as being environmentally disturbed to highly disturbed. In the areas where
environmental loadings have accumulated, 14 regions where environmental risks existed due to high element concentrations were
defined. The model calculations of health risk estimates based on the databases of the Geochemical Atlas for groundwater and
soils indicate that the possible risk occurrence of carcinogenic diseases from groundwater arsenic contents is high in more
than 10% of Slovakia, whereas the chronic risk is negligible. To determinate the background and threshold levels a combined
statistical–geochemical approach was developed and applied as an example for groundwater at the national level as well as
for single groundwater bodies. The results of statistical method application for the whole groundwater body (GBW) were compared
with the background values for anthropogenically non-influenced areas in GBW. Final background value took into account time
variations and spatial distribution of the element in GBW. Furthermore, based on the database from the Geochemical Atlas for
groundwater, groundwater bodies potentially at qualitative risk were delineated for the whole of Slovakia. From a total of
101 groundwater bodies 17 were characterized as being at risk and 22 as being at possible risk. 相似文献
998.
On the occurrence,trace element geochemistry,and crystallization history of zircon from in situ ocean lithosphere 总被引:10,自引:2,他引:8
Craig B. Grimes Barbara E. John Michael J. Cheadle Frank K. Mazdab Joseph L. Wooden Susan Swapp Joshua J. Schwartz 《Contributions to Mineralogy and Petrology》2009,158(6):757-783
We characterize the textural and geochemical features of ocean crustal zircon recovered from plagiogranite, evolved gabbro,
and metamorphosed ultramafic host-rocks collected along present-day slow and ultraslow spreading mid-ocean ridges (MORs).
The geochemistry of 267 zircon grains was measured by sensitive high-resolution ion microprobe-reverse geometry at the USGS-Stanford
Ion Microprobe facility. Three types of zircon are recognized based on texture and geochemistry. Most ocean crustal zircons
resemble young magmatic zircon from other crustal settings, occurring as pristine, colorless euhedral (Type 1) or subhedral
to anhedral (Type 2) grains. In these grains, Hf and most trace elements vary systematically with Ti, typically becoming enriched
with falling Ti-in-zircon temperature. Ti-in-zircon temperatures range from 1,040 to 660°C (corrected for a
TiO2 ≈ 0.7, a
SiO2 ≈ 1.0, pressure ≈ 2 kbar); intra-sample variation is typically ~60–150°C. Decreasing Ti correlates with enrichment in Hf
to ~2 wt%, while additional Hf-enrichment occurs at relatively constant temperature. Trends between Ti and U, Y, REE, and
Eu/Eu* exhibit a similar inflection, which may denote the onset of eutectic crystallization; the inflection is well-defined
by zircons from plagiogranite and implies solidus temperatures of ~680–740°C. A third type of zircon is defined as being porous
and colored with chaotic CL zoning, and occurs in ~25% of rock samples studied. These features, along with high measured La,
Cl, S, Ca, and Fe, and low (Sm/La)N ratios are suggestive of interaction with aqueous fluids. Non-porous, luminescent CL overgrowth rims on porous grains record
uniform temperatures averaging 615 ± 26°C (2SD, n = 7), implying zircon formation below the wet-granite solidus and under water-saturated conditions. Zircon geochemistry reflects,
in part, source region; elevated HREE coupled with low U concentrations allow effective discrimination of ~80% of zircon formed
at modern MORs from zircon in continental crust. The geochemistry and textural observations reported here serve as an important
database for comparison with detrital, xenocrystic, and metamorphosed mafic rock-hosted zircon populations to evaluate provenance. 相似文献
999.
Anton Zubrik David Šaman Soňa Vašíčková Bernd R.T. Simoneit L’udmila Turčániová Michal Lovás Josef Cvačka 《Organic Geochemistry》2009,40(1):126-134
Aliphatic diterpenes were isolated from brown coal from Handlová, Slovakia, using microwave assisted extraction of mechanically activated coal powder. The parameters of the extraction procedure were optimized to get the target compounds in high yield. The total extract was separated using adsorption chromatography. GC–MS revealed tetracyclic and tricyclic diterpanes in the aliphatic fraction; they were identified as 16α(H)-phyllocladane (83%), isopimarane (11%), 18-norisopimarane (4%), abietane (2%) and fichtelite (<0.1%). It was found that more than 2 g of the most abundant diterpane, 16α(H)-phyllocladane could be extracted from 1 kg of Handlová coal. Because of the scarcity of relevant analytical data, 16α(H)-phyllocladane was thoroughly characterized by spectroscopic and chromatographic methods. A complete set of 1H and 13C NMR data is given including their comparison with published values and ab initio calculations. EI mass and IR spectra of 16α(H)-phyllocladane are shown and discussed. Kováts retention indices measured on two common GC stationary phases are also given. 相似文献
1000.
Miyake Y Jiang Q Yuan W Hanari N Okazawa T Wyrzykowska B So MK Lam PK Yamashita N 《Marine pollution bulletin》2008,57(6-12):357-364
Dietary intake is one of the important routes of human exposure to brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs). The use of PBDEs may also result in exposure to polybrominated dibenzo-p-dioxins and dibenzofurans (PBDDs/DFs), as these compounds are impurities in technical mixtures of BFRs and can also be formed unintentionally by the same processes that generate chlorinated dioxins. This study determined the concentrations of polybrominated compounds in common seafood in Guangzhou and Zhoushan, and assessed the health risks of these chemicals via consumption of contaminated seafood. Seafood samples (fish, bivalves, shrimp, crab, and cephalopods) purchased from local markets in 2003 and 2004 were analyzed for PBDEs and PBDDs/DFs. The highest concentration of total PBDEs (46.3 ng g(-1) lipid wt.) was detected in fish from Guangzhou, in which BDEs 47 and 209 were the two predominant congeners. The total daily intakes of PBDEs, PBDDs, and PBDFs were, 946, 6.39, and 6.54 pg kg(-1) body weight (bw) in Guangzhou, and 489, 4.99, and 7.65 pg kg(-1) bw in Zhoushan, respectively. The hazard ratios for PBDDs and PBDFs were both greater than unity, indicating that these compounds may pose some health risks to the local population. 相似文献