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1.
The Chi Chi earthquake (Mw7.6) occurred at 17:47 UTC on Sept. 20,1999 (01:47 September 21, 1999, local time) in central Taiwan. CWB located the epi- center at (120.82°E; 23.85°N) and the focal depth 8 km. Chi Chi earthquake is the best documented earth- quake ever recorded. The abundance and quality of its near-source observations present an unparalleled op- portunity for studying the rupture history from a close distance. More than 400 free field digital accelerome- ters with 3-compon…  相似文献   
2.
近几十年来,蒙古高原和青藏高原的增温速度高于全球变暖的平均水平,导致生态系统的结构和功能发生了显著变化。叶面积指数(LAI)和蒸散发(ET)在塑造陆地表面过程和气候方面发挥着重要作用。在文中,我们重点关注LAI和ET的时空变化及其相互关系。基于2000-2014年的MODIS产品,我们发现蒙古高原的LAI和ET之间存在普遍的正相关关系,而青藏高原则没有协同作用。总体而言,青藏高原LAI的显著增加(减少)区域占总面积的49.38%(50.62%),蒙古高原则为94.92%(5.09%);青藏高原ET增加区域面积占总面积的21.70%(124.10×10~3 km^2),蒙古高原为88.01%(341.60×10~3 km^2)。更重要的是,随着时间的推移,这种关系在整个空间中发生了很大的变化,并且在景观的某些部分发现了不匹配。需要通过观测和/或实验研究来探讨这些关系,包括植被特征及其干扰的影响。  相似文献   
3.
In this paper a semiparametric approach is introduced to decompose an ARFIMA model in the long memory and short memory unobserved components. The procedure is based on the DECOMEL method which produces a statistical decomposition by minimizing the Euclidean distance between the spectrum of the aggregated series and the sum of the parametric spectra of the components. The extension to long memory stationary models is achieved defining an approximate model where the fractional operator is replaced by the ratio of two polynomials of order one. The feasibility and performance of the proposed procedure are discussed through a case study.  相似文献   
4.
Since 1994, the Rumuruti (R) chondrites have been recognized as a new, well-established chondrite group differing from carbonaceous, ordinary, and enstatite chondrites. The first R chondrite, Carlisle Lakes, was found in Australia in 1977. Meanwhile, the number has increased to 107 (December, 2010). This group is named after the Rumuruti meteorite, the first and so far the only R chondrite fall. Most of the R chondrites are breccias containing a variety of different clasts embedded in a clastic matrix. Some textural and mineralogical characteristics can be summarized as follows: (a) the chondrule abundance in large fragments and in unbrecciated rocks is ∼35–50 vol%; (b) Ca,Al-rich inclusions are rare; (c) the olivine abundance is typically 65–78 vol%; (d) the mean chondrule diameter is ∼400 μm; (e) in unequilibrated R chondrites, low-Ca pyroxene is dominating, whereas in equilibrated R chondrites it is Ca-rich pyroxene; (f) the typical olivine in a metamorphosed lithology is ∼Fa38–40; (g) matrix olivine in unequilibrated, type 3 fragments and rocks has much higher Fa (∼45–60 mol%) compared to matrix olivines in type 4–6 lithologies (∼Fa38–41); (h) spinels have a high TiO2 of ∼5 wt%; (i) abundant different noble metal-bearing phases (metals, sulfides, tellurides, arsenides) occur. The exception is the metamorphosed, type 5/6 R chondrite La Paz Icefield 04840 which contains hornblende, phlogopite, and Ca-poor pyroxene, the latter phase typically occurring in low-grade metamorphosed R chondrites only.In bulk composition, R chondrites have some affinity to ordinary chondrites: (a) the absence of significant depletions in Mn and Na in R chondrites and ordinary chondrites is an important feature to distinguish these groups from carbonaceous chondrites; (b) total Fe (∼24 wt%) of R chondrites is between those of H and L chondrites (27.1 and 21.6 wt%, respectively); (c) the average CI/Mg-normalized lithophile element abundances are ∼0.95 × CI, which is lower than those for carbonaceous chondrites (≥1.0 × CI) and slightly higher than those for ordinary chondrites (∼0.9 × CI); (d) trace element concentrations such as Zn (∼150 ppm) and Se (∼15 ppm) are much higher than in ordinary chondrites; (e) the whole rock Δ17O of ∼2.7 for R chondrites is the highest among all meteorite groups, and the mean oxygen isotope composition is δ17O = 5.36 ± 0.43, δ18O = 5.07 ± 0.86, Δ17O = +2.72 ± 0.31; (f) noble gas cosmic ray exposure ages of R chondrites range between ∼0.1 and 70 Ma. More than half of the R chondrites analyzed for noble gases contain implanted solar wind and, thus, are regolith breccias. The 43 R chondrites from Northern Africa analyzed so far for noble gases seem to represent at least 16 falls. Although the data base is still scarce, the data hint at a major collision event on the R chondrite parent body between 15 and 25 Ma ago.  相似文献   
5.
The pharyngeal dental formula of Mylopharyngodon piceus is 4-5 as a rule, and the dentition isasymmetrical. It is difficult to identify each tooth in the larval dentition. In this paper the appearancepattem of tooth germ with developmental process in this fish is described in detail. The formationpattern of the left dentition is contrasted with that of the right one. In the developmental process,the left pharyngeal dentition lacks teeth at position An3. Thus the left dentition is D-type as designatedby Nakajima(1984), while the right one is A-type.  相似文献   
6.
Sanjiang and Jiaodong areas are the important gold regions in China. The gold mineralization is cor- related with the Mesozoic faults and its derivative faults in the granite or the contact zone between granite and base rock. The mineral mapping is one of the important approaches of prospecting mineralogy. The temporal and spatial band distribution of mineral, mineral combination and mineral typomorphism features are natural regularity rules, but this kind of band feature is sometimes hidden and thus in need of mineral typomorphism re- search and mapping to disclose this band feature and to serve for the prospecting of mineral. The changes of the mineral typomorphism feature are often embodied in the " through" mineral, the typomorphism features of the through mineral change like the gradient toward the ore body, and the changes of the features are most obvious and strongest toward the orebodies. The new American mineralogy mapping indicates the weak change of the mineral composition or structure will lead to the change of the shape and wave length position of the specific ab- sorbent feature. Australian experiment lab investigation has held the reason of a series of mineral. The progress achievement of the remote sensing and computer analysis technology now permits a direct comparison directly between the lab and remote sensing data, so the good feature database of the experiment light spectroscopy can serve for drawing of the spacial distribution and remote sensing material. Mineralogy mapping raised the exten- sive emphasis in the international earth arena.  相似文献   
7.
8.
Geochemical patterns from two lag anomalies in the Cobar region of central New South Wales are described. The region is semi-arid, deeply weathered and some areas are covered by variable thicknesses of aeolian and alluvial transported overburden.Lag morphology and mineralogy are related to landform. In erosional landforms the surface is covered by lag, which is composed of coarse fragments derived locally from bedrock and displays varying degrees of ferruginization, together with a range of secondary pisoids. In depositional landforms the lag is less abundant and contains more pisoids. Deflation by sheetwash may lead to lag being partially buried by alluvium. In a large proportion of pisoid lag, hematite and goethite have been converted to maghemite, allowing ready separation into magnetic and non-magnetic fractions. The non-magnetic fraction is dominated by the lithic lag whereas the magnetic fraction is dominated by pisoid lag.The magnetic and non-magnetic components of the 2–11 mm lag fraction, milled to < 75 μm and subjected to HF-HNO3-HClO4 attack, give rise to distinct geochemical patterns at targets related to a variant of the Cobar style of Pb-Zn mineralization with variable silicification and to Zn mineralization in a swarm of quartz and carbonate veinlets. The patterns are influenced by metal source, lag type, surface chemical conditions and landtbrm. Differences in the correlation between metal contents in the magnetic and non-magnetic lag components, and between trace elements and Fe. indicate variable loss of Cu and Zn from the magnetic lag at some targets but retention of Pb. The presence of a readily cxtractable base metal component in the lag has implications for detecting anomalies in transported cover in the region.  相似文献   
9.
城市森林生态服务功能在城市景观规划中应用的思考   总被引:1,自引:0,他引:1  
回顾了景观规划的发展历程,并依据城市森林生态服务功能的内涵,指出当前国内外景观规划中存在的缺陷与不足.旨在通过对二者关系的分析,解读景观生态学理论引入规划中的功能缺失,以期重新唤起人们对于城市森林生态服务功能重要性的关注,并尝试将城市森林生态服务功能的研究成果应用于景观规划领域,为景观规划的定量化提供数据基础和科学依据.  相似文献   
10.
计算机串口记时延迟的测量与分析   总被引:1,自引:0,他引:1  
何峰  郑勇  骆亚波  郭睿 《测绘科学》2009,34(3):41-43
动态测量中,需要记录观测量的观测时刻,时刻作为测量的基本观测量,需要较高的计时精度,通过串口利用计算机计时是一种便捷可行的方法,但串口的时延是必须要考虑的因素。本文介绍了计算机串口计时的原理及影响其时延的相关因素,阐述了进行时延测量的方法,并通过实验对影响串口时延的5种因素进行了相应的测试和分析,实验结果表明,通常情况下串口时延在毫秒级,通过提高计时程序优先级的方法可成功将时延减小至0.35m s以内;低动态条件下串口时延对动态测量的影响较小,在某些检测设备中甚至可以忽略。  相似文献   
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