全文获取类型
| 收费全文 | 5947篇 |
| 免费 | 1237篇 |
| 国内免费 | 1705篇 |
专业分类
| 测绘学 | 439篇 |
| 大气科学 | 1426篇 |
| 地球物理 | 1475篇 |
| 地质学 | 3217篇 |
| 海洋学 | 630篇 |
| 天文学 | 275篇 |
| 综合类 | 722篇 |
| 自然地理 | 705篇 |
出版年
| 2024年 | 22篇 |
| 2023年 | 121篇 |
| 2022年 | 278篇 |
| 2021年 | 342篇 |
| 2020年 | 273篇 |
| 2019年 | 273篇 |
| 2018年 | 400篇 |
| 2017年 | 333篇 |
| 2016年 | 375篇 |
| 2015年 | 338篇 |
| 2014年 | 356篇 |
| 2013年 | 372篇 |
| 2012年 | 313篇 |
| 2011年 | 332篇 |
| 2010年 | 398篇 |
| 2009年 | 351篇 |
| 2008年 | 328篇 |
| 2007年 | 341篇 |
| 2006年 | 247篇 |
| 2005年 | 239篇 |
| 2004年 | 189篇 |
| 2003年 | 173篇 |
| 2002年 | 152篇 |
| 2001年 | 181篇 |
| 2000年 | 197篇 |
| 1999年 | 257篇 |
| 1998年 | 251篇 |
| 1997年 | 242篇 |
| 1996年 | 214篇 |
| 1995年 | 159篇 |
| 1994年 | 153篇 |
| 1993年 | 146篇 |
| 1992年 | 116篇 |
| 1991年 | 88篇 |
| 1990年 | 61篇 |
| 1989年 | 66篇 |
| 1988年 | 60篇 |
| 1987年 | 30篇 |
| 1986年 | 33篇 |
| 1985年 | 18篇 |
| 1984年 | 14篇 |
| 1983年 | 14篇 |
| 1982年 | 9篇 |
| 1981年 | 9篇 |
| 1980年 | 4篇 |
| 1979年 | 4篇 |
| 1975年 | 5篇 |
| 1960年 | 2篇 |
| 1959年 | 1篇 |
| 1958年 | 7篇 |
排序方式： 共有8889条查询结果，搜索用时 49 毫秒
951.
There are two different dust storms in Northeast China, normal dust and alkali dust, from Kerqin sand land and Songnen saline land. As well as visible damages of the dust storms, there are some invisible influences. The authors provide evidences that the bacteria carried by dusts from remote area should not be ignored, but the damages of the alkali dusts are still not clear. 相似文献
952.
腾冲火山区地表垂直形变分析 总被引：11，自引：3，他引：8
对腾冲火山区1998～2000年的3期垂直形变资料进行了分析，进而利用相关资料得出与计算有关的参数，再用多元Mogi模型反演了岩浆房的位置和大小，所得出的结果与地震层析反演结果基本相似。分析反演结果，认为火山区可能存在多个岩浆房，并有岩脉相通。 相似文献
953.
贺兰山群变质杂岩形成于晚太古代,遭受过多期变质和变形的改造,其中发育了不同期次和层次的动力变质岩。变余韧性剪切带内发育了条带状片麻岩和变粒岩,相伴有变余鞘褶皱和构造透镜体,变余韧性剪切带的变形发生在较低的温度、压力条件下,地壳加厚作用的初期。变余糜棱岩貌似条带状片麻岩,但在青石中保留了早期石英拔丝构造和加粗的动态重结晶长石集合体。糜棱岩化作用的温度在550℃以上,变形后沿面理形成了饼状或椭圆状青石,变晶时温度近600℃,压力近300MPa。 相似文献
954.
胡连英 《地球科学与环境学报》1988,(3)
本文论述了中国强震迁移与现代地壳波浪运动间的关系,指出了中国强震时空分布上的波浪性、方向性及丛集性特征,并将中国强震运动划分为天平式运动、单波系波浪运动、双波系波浪运动、多波系波浪运动等类型,进而对强震机制进行了探讨,指出强震波带和强震丛集区仍是今后强震活动的主要场所。 相似文献
955.
V.B. Polyakov S.D. Mineev G. Hu D.A. Khramov V.E. Gorbunov 《Geochimica et cosmochimica acta》2005,69(5):1287-1300
Oxygen isotope equilibrium fractionation constants (β18O-factors) of cassiterite were evaluated on the basis of heat capacity and X-ray resonant (Mössbauer spectroscopy and X-ray inelastic scattering) data.The low-temperature heat capacity of cassiterite was measured in the range from 13 to 340 K using an adiabatic calorimeter. Results of measurements of two samples agree very closely but deviate more than 5% from previous heat capacity data used for calculation of thermodynamic functions. The temperature dependence of heat capacity was treated using the modern version of the Thirring expansion, and the appropriate temperature dependence of the vibrational kinetic energy was found.Measurements of temperature-dependent Mössbauer parameters of cassiterite were conducted in the range from 300 to 900 K. The attempt to describe Mössbauer fraction and the second order Doppler (SOD) shift on the basis of the Debye model failed. The first term of the Thirring expansion of the Mössbauer SOD shift agrees with that calculated from the Sn sublattice vibration density of states (VDOS) obtained via synchrotron X-ray scattering. Based on this agreement we calculated the kinetic energy of the cassiterite Sn sublattice from VDOS.From the kinetic energy of the total cassiterite crystalline lattice and its Sn sublattice, β18O-factors of cassiterite were computed in the temperature range 300-1500 K by the method of Polyakov and Mineev (2000). Appropriate polynomials, which are valid at temperatures above 400 K, are the following:
956.
S-wave velocity and Poisson''''s ratio structure of crust in Yunnan and its implication 总被引：13，自引：2，他引：11
HU Jiafu SU Youjin ZHU Xiongguan & CHEN Yun Geophysical Department of Yunnan University Kunming China Seismological Bureau of Yunnan Province Kunming China Institute of Geology Geophysics Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2005,48(2):210-218
Receiver function of body wave under the 23 stations in Yunnan was extracted from 3-component broadband digital recording of teleseismic event. Thus, the S-wave velocity structure and distribution characteristics of Poisson's ratio in crust of Yunnan are obtained by inversion. The results show that the crustal thickness is gradually thinned from north to south. The crustal thickness in Zhongdian of northwest reaches as many as 62.0 km and the one in Jinghong of further south end is only 30.2 km. What should be especially noted is that there exists a Moho upheaval running in NS in the Chuxiong region and a Moho concave is generally parallel to it in Dongchuan. In addition, there exists an obvious transversal inhomogeneity for the S-wave velocity structure in upper mantle and crust in the Yunnan region. The low velocity layer exists not only in 10.0-15.0 km in upper crust in some regions, but also in 30.0-40.0 km in lower crust. Generally, the Poisson's ratio is on the high side, however it has a better co 相似文献
957.
Hu Xing 《Astrophysics and Space Science》1992,190(1):145-148
On the basis of the model properties of the expansive nondecelerative universe, present temperature of cosmic microwave background and specific entropy in the era of matter, the present parameters of our Universe may be exactly determined. 相似文献
958.
Liu Rui-yuan Hu Hong-qiao Liu Yong-hua Xu Zhong-hua Sato N. Fraser B.J. 《Solar physics》2001,204(1-2):305-313
Simultaneous observations at Zhongshan Station, Antarctica, are presented for the interval of 13–17 July 2000 to show responses
of the polar ionosphere to the Bastille Day (14 July 2000) solar event. The polar ionosphere was highly disturbed, as shown
by frequently large deviations of the geomagnetic H-component, large riometer absorption events and strong ULF waves. Associated
with the huge solar proton event produced by the X5/3B flare, a polar cap absorption (PCA) was observed. It began at ∼ 10:40 UT
on 14 July and ended at ∼ 19:40 UT on 17 July. Superposed on it, there was a large absorption event with a peak of 26 dB,
starting at ∼ 03:00 UT and ending at ∼ 11:10 UT on 15 July. This kind of absorption was probably produced by an intense `cloud
of energetic electrons' during an auroral substorm. The ULF waves were very intense during the main phase and the recovery
phase of the severe magnetic storm on 15 and 16 July. The ionospheric absorption was so strong that the digisonde signal was
blacked out most of the time. The ionosphere returned to normal in the afternoon on 17 July. 相似文献
959.
FENG Xionghan LIU Fan TAN Wenfeng LIU Xiangwen & HU Hongqing . College of Resources Environment Huazhong Agricultural University Wuhan China . Testing Center China University of Geosciences Wuhan China 《中国科学D辑(英文版)》2004,47(8):760-768
Todorokite is one of the common manganese ox-ides in manganese ore deposits, weathering product of manganese-bearing rocks, soils and sediments. It is also an important component in the abundant marine manganese nodules. Since todorokite was firstly found in Japanese Todoroki mine in 1934, its properties and origination have appeared to be very interesting to many researchers[1—3]. It has a stable structure similar to porous molecular sieves, constructed of triple MnO6 octahedral chains. Th… 相似文献
960.
Investigations and assessment of the landslide hazards of Fengdu county in the reservoir region of the Three Gorges project on the Yangtze River 总被引：12，自引：0，他引：12
Shuren?WuEmail author Yimin?Jin Yongshuang?Zhang Jusong?Shi Chen?Dong Weizhi?Lei Ling?Shi Chengxuan?Tan Daogong?Hu 《Environmental Geology》2004,45(4):560-566
The spatial database of landslides in Fengdu County of the reservoir region of the Three Gorges project (TGP) on the Yangtze River was compiled from a variety of different sources including field investigations on landslides, existing catalogues and archives on landslides, reports of meteorological events and human engineering activities that triggered slope failures. The major factors that are found to have affected the slope stabilities are outlined, and an assessment and zonation of landslide hazards of the region is made using an integrated information model, which is divided into destructive, disastrous, likely disastrous and essentially non-disastrous areas from the assessment of landslide hazards. The destructive and disastrous areas are respectively 1.9 and 13.8% of the total region, mostly being nearby townships, highways along the south bank of the Yangtze River and residential quarters along two flanks of the Yangtze River and its distributaries, that will impose direct impact to highway transportation and residential lives, and may effect to some degree the navigation of the Yangtze River, reservoir banks, and building of cities and towns. 相似文献