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871.
T. Leslie Youd Jamieson H. Steidl Robert L. Nigbor 《Soil Dynamics and Earthquake Engineering》2004,24(9-10):639
Instrumented sites provide essential information for understanding and modeling of ground response and ground deformation. For example, significant new lessons were learned from responses at the Wildlife Liquefaction Array (WLA) including: (1) soil softening led to lengthening of period of transmitted ground motions; (2) soil softening also led to attenuation of short-period spectral accelerations (<0.7 s); (3) amplification of long period motions (>0.7 s) occurred due to liquefaction-induced ground oscillation; and (4) ground oscillation led to a continued rise of pore water pressures after strong ground shaking ceased. A new and expanded instrumented site is being developed 70 m downstream from the old WLA site as part of the NSF Network for Earthquake Engineering Simulation (NEES). The new site has more accelerometers, piezometers and ground deformation measurement devices and the data will be streamed to the NEES-grid in near real time. 相似文献
872.
A rock bolt installed in the field for ground support has only one short exposed end on the rock surface. This condition has posed challenges in field instrumentation. In this paper, a new approach for field monitoring of grouted rock bolts using guided ultrasonic waves is proposed with the receiving transducer on the grout surface near the exposed end of the bolt. The effects of the receiver location are studied with numerical modeling. A location correction factor is introduced to correlate the amplitude ratio along the bolt and that on the grout surface. Experiments are conducted to verify the modeling results. This research indicates that it is practically possible to receive meaningful signals with the receiver on the grout surface and that with the recorded data the attenuation and wave velocity of guided waves in grouted rock bolts can be determined with reasonable accuracy. The proper receiver location is found to be 27 to 32 mm from the bolt center for the test condition. 相似文献
873.
874.
有机溶剂辅助微波消解-电感耦合等离子体质谱法测定多种原油中微量金属元素 总被引:2,自引:2,他引:0
建立了二氯甲烷溶剂辅助微波消解-电感耦合等离子体质谱法测定原油中V、Cr、Fe、Ni、Cu、Zn、Mo、Co、Pb等16种微量金属元素。研究表明,用CH2Cl2分散原油样品,以浓HNO3-H2O2为消解体系,采用CEM微波消解系统消解样品,各元素线性关系良好,相关系数≥0.9995;检出限可达ng/L;方法精密度较高,相对标准偏差(RSD,n=3)<5.0%;回收率为92%~110%。以w(Ni)/w(V)与w(Fe)/w(V)比值为变量参数对不同原油样品进行聚类分析,表明国内与国外不同地区原油样品中各金属元素含量差异较大。 相似文献
875.
在王水介质条件下,用自行设计的微色谱柱在线分离富集系统分离富集矿石样品中的痕量金,采用火焰原子吸收光谱法进行测定。在原子吸收光谱仪吸喷溶液的流路上,用P350微色谱柱研究了金的分离富集条件,采用快速吸附和快速洗脱技术,以盐酸溶液为淋洗液,亚硫酸钠溶液为洗脱液,测定一个样品整个分离和测定过程仅需1 min,成功地克服了火焰原子吸收光谱法测定金灵敏度低的缺点。方法的相对标准偏差小于3.2%,检出限为0.078μg/g。与现行离线分离富集方法相比,建立的方法具有高效、快速、成本低廉的优点,经实际样品验证获得了较为满意的结果。 相似文献
876.
877.
电感耦合等离子体发射光谱法测定红土镍矿中镍钴铜 总被引:3,自引:2,他引:1
红土镍矿样品用无水Na2CO3-Na2B4O7混合熔剂熔融,HCl浸出酸化,电感耦合等离子体发射光谱法直接测定样品中镍、钴、铜的含量。Cu 324.754 nm使用Y 371.030 nm作为内标线,Ni 231.604 nm、Co 228.616 nm使用Y 224.306 nm作为内标线校正基体干扰,方法检出限镍为0.5μg/g、钴为1.0μg/g、铜为1.0μg/g,相对标准偏差(RSD,n=7)为1.2%~2.0%,加标回收率为95.0%~103.6%,能满足红土镍矿的分析要求。 相似文献
878.
O. O. Sonibare O. B. Agbaje D. E. Jacob J. Faithfull T. Hoffmann S. F. Foley 《Australian Journal of Earth Sciences》2013,60(7):979-985
The terpenoid composition of fossil resin from the Cape York Peninsula, Australia has been analysed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to determine its origin. The pyrolysis products were dominated by cadalene-based C15 bicyclic sesquiterpenoids including some C30–C31 bicadinanes and bicadinenes typical of Class II resin derived from angiosperm plants of Dipterocarpaceae. This observation contrasts with the Araucariaceae (Agathis sp.) source previously suggested for the resin based on Fourier transform infrared (FTIR) analyses. Dipterocarpaceae are not known in Australian vegetation but grow abundantly in Southeast Asia including New Guinea, indicating that the geological origin of the amber is not the Australian mainland but could be traced to Southeast Asia. 相似文献
879.
Research and Application of Cosmic-ray Fast Neutron Method to Measure Soil Moisture in the Field 总被引:1,自引:0,他引:1
It is very difficult to measure large region soil moisture. In recent years, measurement of surface soil moisture by the cosmic ray fast neutron probe has gradually attracted more attention. By this passive, non-invasive and intermediate scale measurement, soil moisture at a horizontal scale of around 300 m can be observed, which makes this method available to fill the gap between little scale of traditional point measurement and large scale of remote sensing in the measurement of soil moisture. In this paper, Cosmic-ray Soil Moisture Observing System (COSMOS) and Wireless Sensor Network (WSN) were used to observe field soil moisture in Zhangye Oasis. The results of the COSMOS soil moisture well reflected the variation trend of soil moisture at the field scale. There were some regular changes with the cosmic ray soil moisture during the irrigation period. Combined with irrigation data in cosmic-ray probe footprint, a bimodal change was showed in the cosmic-ray soil moisture figure during irrigation period. This was because that the order of irrigation of the three communities was different in cosmic-ray probe footprint. WSN data were used to validate this result and we found that root-mean-square error between cosmic-ray soil moisture and SoilNET average soil moisture was very large during irrigation periods because of the impact of cosmic-ray measurement theory. While root-mean-square error would decrease from 0.037 m3/m3 to 0.028 m3/m3 after we eliminated the data in irrigation period. So COSMOS can be used to measure field soil moisture under high heterogeneity condition and provide truly ground data for the validation of remote sensing 相似文献
880.
The Lower Triassic Kangan Formation in the Persian Gulf (South Pars Gas Field) and its adjacent areas are composed of carbonate–evaporite sequences. These sediments were deposited in a shallow marine homoclinal ramp. Study of the anhydrite-bearing intervals shows various structures and textures. The anhydrite structures are mainly bedded, massive, chicken-wire and nodular type and the main textures are felted, sparse crystal, needle shape, lath shape, equant and fibrous. Pervasive and poikilotopic cement together with replacement and porphyroblastic gypsum are accounted as the most common diagenetic features in anhydrite. Evaluation of anhydrite occurrences and features support both primary and secondary formations. The nodular to chicken-wire anhydrite formed under synsedimentary sabkha conditions, whereas anhydrite cements occurred during the late stages of diagenesis (shallow burial stage). Massive to bedded anhydrite could have been formed under subaqueous conditions or originated by coalescing and continued growth of anhydrite nodules in the sabkha zone. Anhydrite fabrics impose a significant control on the reservoir quality of the Kangan carbonates at the South Pars Gas Field. Thick massive and bedded anhydrite could have been formed as an intraformational seals and anhydrite cements occluded pore spaces and reduced the poroperm values. The sequence stratigraphic analysis revealed two depositional sequences in the studied intervals, which are composed of TST and HST. Investigation of anhydrite throughout depositional sequences indicates a change in the content and style of anhydrite texture. Anhydrite content (volume) decreases upward through transgressive system tract (sea-level rise) whereas, it enhances during highstand system tract (sea-level fall). Pervasive and poikilotopic anhydrite cements together with replacement by anhydrite are prevalent features during transgressive and early highstand system tract. At the late HST, with a progradational stacking pattern, anhydrite value increases and felted, radial, equant, crystalline and mosaic texture are the most common anhydrite fabrics. Sequence boundaries that indicate maximum sea level fall and exposure of successions are marked by the broad anhydrite deposits with massive to bedded and chicken-wire structures and various textures that located in late HST package. There is an unambiguous relationship between the microfacies associations, the evaporite textures, and the sea-level fluctuations. This relationship could lead to a predictable pattern that can be of use as a general guide for the sequence stratigraphic interpretations in the area. 相似文献