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51.
52.
联合利用中国沿岸长期验潮站实测资料和全球海潮模型NAO.99b在中国海域的结果,进行潮汐非调和常数的计算.分别对渤海、黄海、东海和南海进行分析,结果表明,中国海域潮汐类型复杂,渤海、黄海、东海以半日潮性质为主,南海以日潮性质为主;渤海、南海平均大潮差多分布在0.42~2.09 m,平均小潮差分布在0.27~1.33 m,东海、黄海平均大潮差多分布在1.12~4.44 m,平均小潮差多分布在0.41~2.41 m;渤海、黄海平均大潮高潮位分布在0.48~1.77 m,东海在0.42~2.41 m,南海在0.21~1.35 m;渤海、东海以及南海北部浅海海域潮高日不等现象显著. 相似文献
53.
《International Geology Review》2012,54(7):905-914
Twenty-first century advances in both the analytical procedures and instrumentation used in geochronology promise age accuracy better than ±1‰, but realizing this potential requires knowledge of decay constants (λ) that exceed this level. Given the paucity of improved recent measurements of λ, the community has experimented with hybrid methodologies utilizing data largely generated during the 1970s. In this article, we perform a systematic review of laboratory decay constant determinations relevant to geochronology (i.e. 87Rb, 147Sm, 176Lu, 230Th, 232Th, 235U, and 238U), focusing on methodological consistency. For radioisotopes for which multiple studies are available, results are combined through a random effects model to yield the best available values and associated uncertainties. Unfortunately, despite its vital role in modern geochronology, only one experimental determination of 238U decay met our criteria for consideration, significantly limiting the ability to assess its reliability. Thus, utilizing λ238 as an anchor for establishing other decay constants (e.g. 40K, 176Lu, and spontaneous 238U fission) places an unverified result at the core of geochronology. For geochronology to attain its greatest potential, more and better laboratory determinations of decay constants are required, along with a community methodology that permits us to continuously take advantage of new data. 相似文献
54.
Composition, lattice parameters, and room temperature elastic constants of natural single crystal xenotime from Novo Horizonte 总被引:1,自引:1,他引:0
P. Mogilevsky E. B. Zaretsky T. A. Parthasarathy F. Meisenkothen 《Physics and Chemistry of Minerals》2006,33(10):691-698
The composition, lattice parameters, and elastic constants of natural single crystal YPO4 xenotime from Novo Horizonte (Brazil) were determined using EPMA, XRD, and the pulse-echo technique. The composition indicates a 24% substitution of Y sites with other rare-earth elements. The lattice parameters of the studied crystal deviated only slightly from those reported for synthetic YPO4 and were in a good agreement with trends obeyed by other orthophosphates with the xenotime structure. The measured elastic constants C
11, C
33, C
44, and C
66 were consistent with synthetic crystals when porosity was accounted for. C
12 and C
13 constants were evaluated based on the comparison with other materials with xenotime structure. The elastic constants could be rationalized using interionic force constants and bond energies.
相似文献
P. MogilevskyEmail: |
55.
Detailed studies of the internal motions of dark clouds using spectral lines of many molecules require a laboratory frequency accuracy of the order of a few m s?1. Based on our laboratory studies of the HNCO rotational spectrum in the ground vibrational state, we have increased significantly the accuracy of frequency calculation in a wide range of quantum numbers. We have achieved an (1σ) uncertainty for rotational transitions in the K a = 0, 1 states recalculated to the Doppler velocity scale ≤2 m s?1 for all frequencies <1.1 THz. This value allows radio-astronomical measurements with an accuracy comparable to that of the highest-precision observations based on spectral lines of other molecules. 相似文献
56.
月球大地测量学的进展 总被引:11,自引:0,他引:11
陈俊勇 《大地测量与地球动力学》2004,24(3):1-6
介绍了月球大地测量(Selenodesy)的定义和方法。月球大地测量的一个特点是它的观测数据绝大部分都要依靠航天探测器或环月、绕月卫星来获取。月球大地测量的内容可以考虑3个方面:一是在月球上给出一个有确定定义的坐标参考系。并在其中布测一个控制网;二是确定这一月球参考系的大地测量几何和物理常数;三是求定月球的外部重力场。 相似文献
57.
José Antonio Belinchón 《Astrophysics and Space Science》2009,323(2):185-195
We study a perfect fluid Bianchi II models with time varying constants under the self-similarity approach. In the first of
the studied model, we consider that only vary G and Λ. The obtained solution is more general that the obtained one for the classical solution since it is valid for an equation
of state ω∈(−1,∞) while in the classical solution ω∈(−1/3,1). Taking into account the current observations, we conclude that G must be a growing time function while Λ is a positive decreasing function. In the second of the studied models we consider
a variable speed of light (VSL). We obtain a similar solution as in the first model arriving to the conclusions that c must be a growing time function if Λ is a positive decreasing function. 相似文献
58.
Single-grain dating of quartz near saturation is shown to have the potential of under-estimating equivalent dose. Experimental work shows that dose recoveries can be under-estimated when the administered dose approaches saturation, an observation also seen by Duller (2012). Duller (2012) found that by calculating the ratio between the fast and medium bleaching components, the “fast ratio”, for each grain, the under-estimation can be corrected by removing those grains with low fast ratios. Similar results are shown for samples from archaeological sites in South Africa and South Carolina. To understand why grains with low fast ratios might lead to equivalent dose under-estimation, simulations using a comprehensive quartz model was employed. It was found that large grain-to-grain variation in the decay constants for the fast and medium components can cause this effect. 相似文献
59.
论证了验潮站潮汐调和常数的精度指标与精度评估方法,对中国沿岸有代表性的长期验潮站分别按年、月调和分析结果序列进行了调和常数的精度统计计算。结果表明,对于面向开阔海域的验潮站,由年观测资料分析的主要分潮振幅具有毫米级精度,月分析结果具有厘米级精度。而分布于黄海、东海沿岸和北部湾的验潮站,由年、月观测序列求得的调和常数均存在较大量级的趋势性或周期性变化成分。为海图深度基准面计算和潮汐模型精度评价的需要,对调和常数实施修正和规定参考历元是必要的。 相似文献
60.