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961.
钢筋混凝土柱的破坏与能量吸收 总被引:2,自引:0,他引:2
本文根据作者所做钢筋混凝土柱的低周疲劳试验,就钢筋混凝土柱的破坏与其能量吸收之间的关系进行了分析。 相似文献
962.
宋友桂 《华东地质学院学报》1998,21(2):123-127
本文对天目山龙王庙地剖面样品的测试分析,得出以下结论:1.古地磁揭示,该剖面主要属布容正极性世,地层年代属于Q3-Q。4 相似文献
963.
964.
利用中国科学院禹城试验站的系列气象观测资料计算了逐日潜在腾发量(ETP).将日潜在腾发量系列分解为均值项和随机项两个部分,利用标准差对随机项进行了标准化处理.而后着重研究了标准化以后的随机序列的随机过程特征.首先,建立了该系列的离散的时间序列模型,然后在此基础上建立了相应的连续参数的随机模型,取得了该序列的理论概率分布密度和稳态概率分布密度,并得到了观测结果的验证,同时,还得到了该序列的自相关函数和谱密度函数的解析表达式,从而比较全面地分析了腾发量系列的随机过程特性. 相似文献
965.
966.
商洛地区金属矿产成矿系列刍议 总被引:1,自引:1,他引:0
本文以赋矿岩石建造及成矿作用为依据,将商洛地区主要金属矿产分为三个系列,24个亚系列,指出不同成矿系列相互迭加,构成各具特色的成矿带。 相似文献
967.
热电离质谱铀系法测定碳酸盐标样 总被引:5,自引:0,他引:5
用高精度热电离质谱(TIMS)铀系法测定碳酸盐标样的年龄,测定结果与α谱仪铀系法进行比较,铀含量和年龄值均吻合。方法对U的回收率可达95%,Th为92%。TIMS铀系法具有样品用量少、测试时间短、精度高的优点。 相似文献
968.
Design charts that enable quick determination of the probability distribution parameters related to the ultimate bearing capacity of shallow foundations resting on (c = 0) soils are developed. These charts are intended to assist foundation designers and analysts in studying the reliability of structures as related to the capacity of the foundation system. The approach presented herein provides a more reliable alternative to foundation design and analysis than the current conventional design procedure which employs the assumption of an appropriate factor-of-safety. © Rapid Science Ltd. 1998 相似文献
969.
A lumped-parameter model of groundwater balance is proposed that permits an estimate of discharge variability in comparison
with the variability of recharge, by taking into account the influence of aquifer parameters. Recharge–discharge relationships
are analysed with the model for cases of deterministic and stochastic recharge time-series variations. The model is applied
to study the temporal variability of groundwater discharge in a river valley in the territory of Tajikistan, an independent
republic in Central Asia.
Received, April 1996 Revised, August 1997 Accepted, March 1998 相似文献
970.
Mean orbital elements are obtained from osculating ones by removing the short periodic perturbations. Large catalogues of
asteroid mean elements need to be computed, as a first step in the computation of proper elements, used to study asteroid
families. The algorithms for this purpose available so far are only accurate to first order in the masses of the perturbing
planet; the mean elements have satisfactory accuracy for most of the asteroid belt, but degraded accuracy in the neighbourhoods
of the main mean motion resonances, especially the 2:1. We investigate a number of algorithms capable of improving this approximation;
they belong to the two classes of Breiter-type methods and iterative methods. The former are obtained by applying some higher
order numerical integration scheme, such as Runge–Kutta, to the differential equation whose solution is a transformation removing
the fast angular variables from the equations; they can be used to compute a full second order theory, however, only if the
full second order determining function is explicitly computed, and this is computationally too cumbersome for a complicated
problem such as the N-body. The latter are fixed point iterative schemes, with the first order theory as an iteration step,
used to compute the inverse map from mean to osculating elements; formally the method is first order, but because they implement
a fixed frequency perturbation theory, they are more accurate than conventional single iteration methods; a similar method
is already in use in our computation of proper from mean elements. Many of these methods are tested on a sample of asteroid
orbits taken from the Themis family, up to the edge of the 2:1 resonance, and the dispersion of the values of the computed
mean semimajor axis over 100 000 years is used as quality control. The results of these tests indicate that the iterative
methods are superior, in this specific application, to the Breiter methods, in accuracy and reliability. This is understood
as the result of the cancellations occurring between second order perturbation terms: the incomplete second order theory,
resulting from the use of a Breiter method with the first order determining function only, can be less accurate than complete,
fixed frequency theories of the first order. We have therefore computed new catalogues of asteroid mean and proper elements,
incorporating an iterative algorithm in both steps (osculating to mean and mean to proper elements). This new data set, significantly
more reliable even in the previously degraded regions of Themis and Cybele, is in the public domain.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献