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991.
本文利用主应变比异常理论分析了祁连建站以来地应变观测资料,认为肃南──祁连断裂段上及附近发生的地震是由于构造应力场的变化,在引张应力状态下,正断层或走滑断层易于活动而导致的。 相似文献
992.
F. Amini 《Soil Dynamics and Earthquake Engineering》1995,14(6):439-443
Two types of clayey soils, a kaolinite and a bentonite, were tested using a resonant column apparatus under random excitation conditions. The concept of root mean square (rms) strain was utilized for the purpose of strain calculations during random loading. The conventional estimator of the transfer function was used for random vibration analysis. The effect of confinement duration (at a constant pressure) on dynamic soil properties, namely damping and shear modulus, was evaluated. The results indicate that for both cohesive soils, the effect of time was less pronounced during random vibration than sinusoidal loading at the same rms strain. This effect is however more pronounced when the peak shearing strain of sinusoidal loading is considered. Furthermore, time effects were more pronounced at low strain levels than at high strain levels. 相似文献
993.
Field survey of the 1994 Mindoro Island,Philippines tsunami 总被引:2,自引:0,他引:2
Fumihiko Imamura Costas E. Synolakis Edison Gica Vasily Titov Eddie Listanco Ho Jun Lee 《Pure and Applied Geophysics》1995,144(3-4):875-890
This is a report of the field survey of the November 15, 1994 Mindoro Island, Philippines, tsunami generated by an earthquake (M=7.0) with a strike-slip motion. We will report runup heights from 54 locations on Luzon, Mindoro and other smaller islands in the Cape Verde passage between Mindoro and Luzon. Most of the damage was concentrated along the northern coast of Mindoro. Runup height distribution ranged 3–4 m at the most severely damaged areas and 2–4 in neighboring areas. The tsunami-affected area was limited to within 10 km of the epicenter. The largest recorded runup value of 7.3 m was measured on the southwestern coast of Baco Island while a runup of 6.1 m was detected on its northern coastline. The earthquake and tsunami killed 62 people, injured 248 and destroyed 800 houses. As observed in other recent tsunami disasters, most of the casualties were children. Nearly all eyewitnesses interviewed described the first wave as a leading-depression wave. Eyewitnesses reported that the main direction of tsunami propagation was SW in Subaang Bay, SE in Wawa and Calapan, NE on Baco Island and N on Verde Island, suggesting that the tsunami source area was in the southern Pass of Verde Island and that the wave propagated rapidly in all directions. The fault plane extended offshore to the N of Mindoro Island, with its rupture originating S of Verde Island and propagating almost directly south to the inland of Mindoro, thereby accounting for the relatively limited damage area observed on the N of Mindoro. 相似文献
994.
Yoichiro Fujii 《Pure and Applied Geophysics》1995,144(1):19-37
In order to study characteristics of horizontal crustal strains, we divide the Japanese Islands into 14 tectonic provinces
consistent with the suggestion given byMatsuda (1990). We calculate frequency distribution of strain rates using the results of the Precise Control Survey initiated by
the Geographical Survey Institute in 1973. This survey is a revision of old first- and second-order triangulation networks
by trilateration. The principal axes and principal strains inside all the geodetic triangles are deduced from the comparison
of the old triangulation and the new trilateration networks. The maximum shear strain rates are calculated by dividing the
accumulated strains with the time intervals. The frequency distribution of strain rates is counted for each tectonic province
and for the entire Japanese Islands.
It is proved that the maximum shear strain rate with highest frequency ranges from 0.10–0.15 microstrain/a for 4409 data in
the Japanese Islands. The mean value of the strain rates throughout the Japanese Islands is deduced to be 0.18 microstrain/a.
We also calculated a mean value of strain rates for each tectonic province. Comparison is made between mean geodetic strain
rates in the provinces and Quaternary strain rates estimated by geomorphic data. It is found that 0.3–0.4 microstrain/a of
the highest order strain rate is now prevailing in the Izu province, the south Fossa-Magna collision zone, and some special
provinces along the eastern part of the Japan Sea coast. 相似文献
995.
对华北地区韧性剪切带几种代表上、中、下地壳深度的糜棱岩及其围岩在高温高压条件下进行纵波速度测定及各向异性研究.对实验样品的纵波速度测定得到以下结果:1.沿糜棱岩面理方向的纵波速度大于与面理垂直方向的纵波速度,差值为0.15-0.30km/s,各向异性为3%-5%;2.糜棱岩的纵波速度低于其围岩的纵波速度,差值为0.10-0.45km/s;3.中地壳角闪岩相糜棱岩的纵波速度各向异性高于上地壳绿片岩相糜棱岩和下地壳麻粒岩相糜棱岩的各向异性;4.地震波速各向异性与糜棱岩矿物优选定向有关. 相似文献
996.
利用新近获得的子午面磁盔-电流片背景太阳风稳态解,对激波从盔底沿电流片方向往外传播时与磁盔间的相互作用进行了数值模拟研究,重要新结果是:1.磁盔的存在使受扰介质速度跃变中央出现下凹,随着激波传出磁盔区并沿电流片方向传播,速度下凹逐渐减弱以致消失;2.激波将磁盔拉长并把盔顶的环形(垂直赤道面)磁场带到行星际空间,成为行星际磁场南向分量的来源之一;3.5个太阳半径(R⊙)内的磁盔部分将出现精细结构,沿盔外边界形成两条高速带,以及马蹄形密度(亮)环形结构等.这些结果表明,太阳附近高速等离子体与磁盔间存在重要的动力学相互作用过程,对行星际空间的太阳风三维结构有重要影响. 相似文献
997.
998.
999.
典型构造背景应变场特征及其演化趋势 总被引:6,自引:1,他引:6
在外力作用下,一定的构造形式周围会产生特定的应变图象。其形态特征在失稳过程中会发生变化。研究应变图象的特征及其变化有助于鉴别失稳前兆,预测变形发展趋势。受构造形式控制,应变场在空间分布上可以划分为若干区域。在变形与失稳过程中,各个区域既有不同的变形行为,也相互影响、相互制约,构成一个紧密联系的动态体系。因此,应当全面观测应变场图象的时间与空间动态演化过程,从中获取失稳前兆,分析失稳机制 相似文献
1000.
复杂构造应力扰动场与发震构造识别问题的研究 总被引:7,自引:2,他引:7
在地震短临阶段异常是由局部断层扩展或弱化引起。实验与数值模拟结果曾得到与之相伴的是平均应力扰动场的四象限分布和最大剪应力扰动场的八瓣式分布。为检验此结果的普适性作了进一步的研究。结果表明不论区域构造及其基本应力场如何复杂,这种四象限分布与八瓣式分布型式不变,这为最终判定失稳区提供了依据。与此同时,在复杂构造情况下这种应力扰动场的畸变也不容忽视 相似文献