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排序方式: 共有732条查询结果,搜索用时 218 毫秒
31.
Xian-Kang Zhang Zhuo-Xin Yang Yu-Chun Yang Jian Yang Jian-Li Song Ping Zhao 《地震学报(英文版)》1995,8(4):519-529
In this paper, the theory and method, obtaining the tomographic determination of three-dimensional velocity structure of the
crust by use of the joint inversion of explosion and earthquake data, are given. The velocity distribution of the crust is
regarded as a continuous function of the spatial coordinates without parametrization of the velocity model ahead, so that
the inversion solution would not be influenced by different parametrization procedures. The expressions of integration kernels,
which relates the two kinds of data sets, are also given. The authors have processed the observed data in Tangshan earthquake
region by the method proposed in this paper, and obtained the tomographic results of the middle and upper crust structures
in this region. The comparison of these results with the result obtained only by the explosion data, has also been made. 相似文献
32.
J. Gani P. Todorovic 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(3):209-216
A simple two-dimensional random walk model is developed for the motion of a particle in a fluid flow. Some earlier results for the persistent injection of particles into the flow are extended, and the distribution of the maximum number of particles in suspension over the period (0,t) is derived. 相似文献
33.
高烈度区连续梁桥的减震设计方法研究 总被引:2,自引:1,他引:2
本文以高烈度区的某三跨连续梁桥为例,分别采用基础隔震和消能减震两种措施进行结构的减震分析;针对隔震结构减震效果好但主梁位移过大的特点,提出了在采用铅芯橡胶隔震支座的同时设置粘滞阻尼器的减震方案,其非线性时程分析结果表明,该方案能有效地降低结构的地震反应,可供工程实践参考。 相似文献
34.
Manfred Teschner Eckhard Faber Jürgen Poggenburg Georgios E. Vougioukalakis Georgios Hatziyannis 《Pure and Applied Geophysics》2007,164(12):2549-2571
In this paper the installation and long-term operation of a system for continuous monitoring of fumarolic gases is described.
Several physicochemical and gas-geochemical parameters such as the concentration of CO2, H2S and CO in the fumarolic emissions, as well as the temperatures of the hydrothermal steam and soil in close vicinity of the
fumarole and steam pressure are measured in short-time intervals (typically 15 seconds). Data are logged on-site and in parallel
transferred to a remote station by digital telemetry. Specially developed software enables the real-time observation of the
local conditions in the crater and full bidirectional control of the monitoring system. Fluctuations in the monitored parameters
are also reported. From the data presented it can be concluded that environmental conditions (direction and strength of wind,
precipitation) will interact with some of the parameters monitored. These influences can only be revealed by continuously
operated monitoring systems. 相似文献
35.
长螺旋钻孔泵压灌注CFG桩缩径与对策 总被引:1,自引:0,他引:1
CFG桩是水泥粉煤灰碎石桩的简称。长螺旋钻孔泵压灌注CFG桩在层状土层的软硬分界处及软土中出现缩径,通过降低提钻速率和设置降水井点,缩径问题有所缓解,采取复打技术后彻底解决了缩径问题。 相似文献
36.
考虑利用卫星像片进行制图问题,对于需要两张或更多张卫片才能覆盖的地区进行连续制图时,需要研究多张卫片的图像镶嵌问题,利用二面投影原理对卫片原的镶嵌问题进行了研究,主要考虑两张相邻卫片的几何配准问题。 相似文献
37.
38.
Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric
CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO2 concentrations (of about 5 μmol·mol-1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO2 concentrations occur between 02:30-05:30 AM (local time) and the minimum levels occur between 12:00-15:30 PM. The atmospheric
CO2 concentrations in the summer of 2002 were around 5 μmol·mol-1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the
daily mean atmospheric H2O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO2 and H2O concentrations. We therefore suggest that the near-surface atmospheric CO2 concentration is affected not only by photosynthesis and respiration, but also by the air H2O content in the glaciated region around Muztagata. 相似文献
39.
40.
首先对比较简单的单分量信号和多分量信号进行时-频分析,对比了不同时-频分析方法(STFT、WD、Hilbert时-频谱分析、连续小波分析)的分析精度。结果表明对单分量信号和可以分解为若干单分量信号叠加的多分量信号,Hilbert时-频谱分析精度最好,WD和STFT次之,连续小波变换的精度最差;由于Hilbert时-频谱分析和WD方法要求信号为单分量信号或可以分解为若干单分量的信号,故其不适用于复杂信号的时-频分析;对多分量信号,STFT时-频谱较连续小波时-频谱精度高些。需要指出的是,当使用STFT方法时,取不同的窗参数,STFT的时-频分析精度相差很大,必须使用合适的窗参数,以取得较好的分析效果。此外还对El Centro波的两水平分量和人工合成的地震动进行了时-频分析,虽然STFT的时间分辨率和频率分辨率存在矛盾,但它对信号的适应性最强,对复杂信号的时-频分析精度一般可以满足需要,而连续小波变换进行信号的时-频分析时,时-频分辨精度最差,且对于大于30Hz的频率分量,随频率的增加,时-频分析的效果和精度迅速变差,说明小波变换并不适合于做时-频分析,尤其对于高频信号,用连续小波变换得到的时-频谱图看起来很粗糙,而且很难准确解释。进一步对比了真实地震动和人工地震动的时-频分布,认为用胡聿贤教授合成人工地震动的方法合成的地震动在时-频域上的分布和真实地震动相似。 相似文献