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971.
972.
本文通过对裁剪窗口以及被裁剪图形的相关性的分析和判别,找出其左右方向关系,论证了“同向认定图形裁剪法”的可行性,并给出了具体实现方法。 相似文献
973.
We investigated the ‘local’ and ‘global’ similarity of vertical turbulent transfer of heat, water vapour, and CO2 within an urban surface layer. The results were derived from field measurements in a residential area of Tokyo, Japan during midday on fair-weather days in July 2001. In this study, correlation coefficients and quadrant analysis were used for the evaluation of ‘global’ similarity and wavelet analysis was employed for investigating ‘local’ similarity. The correlation coefficients indicated that the transfer efficiencies of water vapour and CO2 were generally smaller than that of heat. Using wavelet analysis, we found that heat is always efficiently transferred by thermal and organized motions. In contrast, water vapour and CO2, which are passive quantities, were not transferred as efficiently as heat. The quadrant analyses showed that the heat transfer by ejection exceeded that by sweep, and the ratios of ejection to sweep for water vapour and CO2 transfer were less than that for heat. This indicated that heat is more efficiently transferred by upward motions and supported the findings from wavelet analysis. The differences of turbulent transfer between heat and both CO2 and water vapour were probably caused both by the active role of temperature and the heterogeneity in the source distribution of scalars 相似文献
974.
Gehad M. Saleh 《中国地球化学学报》2006,25(2)
The Zargat Na'am ring complex crops out 90 km NW of Shalatin City in the Southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. It is cut by two sets of joints and faults which strike predominantly NNW-SSE and E-W,and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. It consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills.The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFSM), such as Zr and Nb. The highest concentrations ( 1.5 wt% Zr, 0.25 wt% Nb,0.6 wt% ∑REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartzhosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750 × 10-6), Zr (2500 × 10-6) and REEs (1450 × 10-6). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions. 相似文献
975.
976.
宁波夏季强对流和台风短时暴雨雷达回波特征对比分析 总被引:3,自引:1,他引:3
为了对比宁波地区夏季强对流短时暴雨和台风短时暴雨的多普勒雷达回波特征,选取2004年和2005年该地区夏季出现的强对流短时暴雨和台风短时暴雨的个例作为研究对象,从回波的发展演变、回波形态及回波产品值等进行分析比较,发现:这两类短时暴雨在回波强度、回波高度及垂直液态水含量等产品有明显差异,而降水产品如OHP,STP估计的雨量值,在这两种天气过程中,均比实况雨量资料偏小,且实况雨量越大,偏差也越大;另外,在分析中也发现,用雷达缺省的Z-I关系来估计雨量有很大误差,特别是在台风降水过程中;最后分别建立了对流性降水与台风降水的Z-I关系,以修正宁波夏季的降水估计值。 相似文献
977.
978.
Akio Kitoh 《Natural Hazards》2007,42(2):261-272
There is a close relationship between interannual variability of the Indian summer monsoon rainfall and the El Niño/Southern Oscillation (ENSO) (drought conditions over India accompany warm ENSO events and vice versa). However, recent observations suggest a weakening of this ENSO-monsoon relationship that may be linked to global warming. We report here an analysis of the ENSO-monsoon relationship within the framework of a 1000-year control simulation of the MRI-coupled general circulation model (GCM), MRI-CGCM2.2. An overall correlation between the June-July-August (JJA) Nino3.4 sea surface temperature and the JJA Indian monsoon rainfall is –0.39, with reasonable circulation characteristics associated with the modeled ENSO. The simulated ENSO-monsoon relationship reveals long-term variations, from –0.71 to +0.07, in moving 31-year windows. This modulation in the ENSO-monsoon relationship is associated with decadal variability of the climate system. 相似文献
979.
不整合分类研究进展与新型分类方案 总被引:6,自引:0,他引:6
总结了前人对不整合类型的划分工作和不整合形态特点,在此基础之上,根据不整合的成因机制和不整合形态的主控因素,提出了新型不整合分类方案,将不整合分为七个大类,包括削截不整合、褶曲不整合、底辟不整合、震积不整合、古岩溶不整合、超覆不整合和假整合,并进一步细分为13个亚类。新型的不整合分类考虑了震积作用研究等最新的地质学进展,吸收了许多有益成果,扩充了不整合类型,更加关注盆地的自身特点,通过剔除重复类型等方法,使不整合分类方案更加完备,具有较高的科学性和实用性。文中还以国内外有关油田为例分析了不整合类型基本特征。 相似文献
980.
邓肯E-B模型无法描述软化土体的应力应变关系以及土体的剪胀效应;采用抛物线型体应变曲线的南水模型破坏时的剪胀率趋于定值,与实际土体不符。但南水模型适合描述应力应变峰值点前或最大剪胀率前土体的本构关系,邓肯模型适合描述的应变范围更小。因此,若要进行土工结构渐进破坏的分析计算,则需要建立一个适合于描述直至破坏的更大应变范围的土体本构关系。采用损伤扰动概念,将变形过程中的土体视为“相对完整”的未损伤土体和“完全调整”扰动土体的混合体,其应力应变关系可根据损伤扰动程度,由各自的应力应变关系组合确定。并根据试验提出了确定损伤扰动函数的计算公式。对体应变曲线,则采用抛物线加双曲线的形式加以描述。 相似文献