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101.
基于INPHO系列软件的数字正射影像图的制作   总被引:1,自引:0,他引:1  
戴小真 《现代测绘》2007,30(5):27-29
INPHO是德国专业的数字摄影测量系统软件,包含空三加密、数字地面模型匹配、及数字正射影像纠正、影像拼接等日列软件。本文以数字航空影像(DMC影像)为例,阐述利用INPHO制作正射影像图的方法,进一步指出制作过程中的一些注意事项。  相似文献   
102.
近年来公共财政的使用往往要接受审计机关的追踪问效。信息化建设通常投资规模较大,无疑成为审计的重点对象。但是,审计只是来自外部的事后监督,虽然发现了问题,许多损失却已既成事实。因此,信息化建设甚至有时被形容为吞噬投资的"黑洞"。应该说,为了有效地防范问题和损失,使用公共资金的机构亟需在内部建立及时的"成本-效果"反馈机制,提前进行自我审计。针对于此,本文借鉴目前国内外已有的一些绩效评估工具,根据政府信息化建设的特点,提出一种较为简单、可操作的持续评估方法。  相似文献   
103.
本文应用先进的微束分析技术-质子探针分析方法对安徽中部沙溪斑岩铜(金)矿床中金的赋存状态进行系统的研究。结果表明,该斑岩铜(金)床中金的赋存状态以微细粒微米级的自然金形式存在,其载体矿物主要为黄铁矿和黄铜矿。本研究对斑岩铜(金)矿床中金的综合利用提供了理论上的依据,同时也为其它同类矿床中金的赋存状态提供了新的研究方法。  相似文献   
104.
Gamma-ray bursts: post-burst evolution of fireballs   总被引:3,自引:0,他引:3  
The post-burst evolution of fireballs that produce γ-ray bursts (GRBs) is studied, assuming the expansion of fireballs to be adiabatic and relativistic. Numerical results as well as an approximate analytic solution for the evolution are presented. Owing to the adoption of a new relation between t R and γ, our results differ markedly from previous studies. Synchrotron radiation from the shocked interstellar medium is carefully calculated, using a conventional set of equations. The observed X-ray flux of GRB afterglows can be reproduced easily. Although the optical afterglows seem much more complicated, our results can still present a rather satisfactory agreement with observations. We also find that the expansion will no longer be highly relativistic about 4 d after the main GRB. We thus suggest that the marginally relativistic phase of the expansion should be investigated so as to check the afterglows observed a week or more later.  相似文献   
105.
数字遥测地震台网采用无线信道在国内地震界借鉴的经验还非常有限。究竟数字无线遥测,能否在(10^-6)误码率指标下,象模拟无线遥测地震台网一样采用单向传输,尚有不同看法。从三峡无线数字遥测地叶网的成功勘选得一邓许多有益的结果,我们关于鸨线信道和信道设备的探索回答了这个问题。结论是:数字地震台网仍然可以采用无线遥测方式组网,采用传输的信道设备既经济原则,技术上也是可行的。  相似文献   
106.
Activities to provide energy for an expanding population are increasingly disrupting and changing the concentration of atmospheric gases that increase global temperature. Increased CO2 and temperature have a clear effect on growth and production of rice as they are key factors in photosynthesis. Rice yields could be increased with increased levels of CO2, however, the rise of CO2 may be accompanied by an increase in global temperature. The effect of doubling CO2 levels on rice production was predicted using rice crop models. They showed different effects of climate change in different countries. A simulation of the Southeast Asian region indicated that a doubling of CO2 increases yield, whereas an increase in temperature decreases yield.Enhanced UV-B radiation resulting for stratographic ozone depletion has been demonstrated to significantly reduce plant height, leaf area and dry weight of two rice cultivars under glasshouse conditions. Data are still insufficient, however, for conclusive results on the effect of UV-B radiation on rice growth under field conditions.Rice production itself has a significant effect on global warming and atmospheric chemistry through methane emission from flooded ricefields. Water regime, soil properties and the rice plant are major factors controlling the flux of methane in ricefields. Global and regional estimates of methane emission rates are still highly uncertain and tentative. Integration of mechanistic modeling of methane fluxes with geographic information systems of factors controlling these processes are required to improve estimates and predictions.  相似文献   
107.
Robust估计的算法优化   总被引:2,自引:0,他引:2  
苏思光  戴嘉芸 《测绘学报》1996,25(2):151-155
本文分析了Robust估计收敛慢的原因,提出以最小二乘平差的残差(V)为初始信息,用L1估计的权函数所计算的权力初始权,根据迭代计算的残差的大小,及残差的变化所提供的信息,构造出加速收敛的算法,计算结果表明,较之一般的方法,迭代次数显著减少,辨识杠杆点含粗差的能力有较大提高,即搜索粗差的效率有很大提高。  相似文献   
108.
Timber structures are characterized by a pinching phenomenon that leads to reduced dissipative capability. A few hysteretic models have been proposed to simulate the mechanical behavior of timber structures, among which the one composed of a bilinear element and a slip element in parallel has been popular in practice. Based on this model, this paper expands on the existing seismic control design methodology to determine the capacity of hysteretic dampers for multi-story timber structures. The equivalent linearization method for a single-degree-of-freedom timber structure with added hysteretic damper is established and is verified through nonlinear timber history analysis over a wide range of structural parameters. The design formulas for determining the damper capacity for a multi-degree-of-freedom system are derived, based on the concept of adjusting the distribution of equivalent stiffness of structure. The seismic control design is applied to many buildings with randomly generated parameters and the effectiveness is confirmed through a nonlinear time history analysis with four sets of seismic excitations. An extended study has shown that the shear force pattern plays an important role in the seismic control design results and thus the performance of structures. The effectiveness of the control of residual deformations by adding dampers is also studied.  相似文献   
109.
300年来中国森林的变化   总被引:3,自引:2,他引:3  
Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are estimated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years (AD 1700-1998) is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×10^8 hm^2 (or 9.2% of the coverage rate) in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated descending. The forest area was reduced by 1.66×10^8 hm^2 (or 17% of the coverage rate) in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×10^8 hm^2 (or 8% of the coverage rate) in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and decreasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Province, it dropped by 35%. During the recovery period 1949-1998, the western provinces, municipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Sichuan-Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions (except Heilongjiang, Hubei, Jiangsu-Shanghai) have achieved an increase over 5%, among which the Guangdong-Hainan, Guangxi, Anhui, Beijing-Tianjin-H  相似文献   
110.
The definition Tor stability D of standing waves given in this paper is used to denote the relative magnitude of annual variation of the waves. Analysis of the temporal (seasonal) and spatial (meridional) changes of the monthly mean circulation at 500 and 100 hPa shows its temporal and spatial demarcation and the bourdary be-tween the middle-and-low latitude circulation and the middle-aod-high latitude circulation in the wave field. Based on the annual march of D and the position of the boundary, a discussion is made of the seasonal trans-formation of the Northern- Hemisphere mean circulation and Ihe- pattern of its development.  相似文献   
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