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991.
FU Jun-ping ZHANG Hao-jingZHANG Xiong XIONG Ding-rongGUO Fei 《Chinese Astronomy and Astrophysics》2014
We have collected the 37 GHz radio data of PKS 1510-089 from 1990 to 2005, and obtained its long-term light curve after making data processing. From the light curve we can find that the activity in PKS 1510-089 is very strong. In this paper, the Period04 method is used for the first time to analyze the light periodicity of PKS 1510-089. The result indicates that its radio emission at 37 GHz has the periods of (1.87±0.13) yr and (0.87±0.07) yr. This result is consistent with the results obtained by Xie et al. in 2004, 2005, 2008, and Wu et al. in 2005 with other methods of data analysis. 相似文献
992.
The European Centre for Medium-Range Weather Forecasts Re-Analysis Interim
(ERA-Interim) meteorology and measurements from the Microwave Limb Sounder,
High Resolution Dynamics Limb Sounder, and Ozone Monitoring Instrument
onboard the Earth Observing System Aura satellite were applied to analyze
the dynamical and chemical features of a cutoff low (COL) event over
northeast China in early July 2007. The results showed the polar
stratospheric origin of an upper-level warm-core cyclone at 100--300 hPa,
associated with a funnel-shaped tropopause intruding into the
mid-troposphere just above the COL center. The impacts of the stratospheric
intrusion on both column ozone and ozone profiles were investigated using
satellite measurements. When the intensity of the COL peaked on 10 July
2007, the total column ozone (TCO) increase reached a maximum (40--70 DU).
This could be dynamically attributed to both the descent of the tropopause
(~75%) and the downward transport of stratospheric ozone across the
tropopause (~25%). Analysis of the tropospheric ozone profiles
provided evidence for irreversible transport/mixing of ozone-rich
stratospheric air across the tropopause near the upper-level front region
ahead of the COL center. This ozone intrusion underwent downstream transport
by the upper tropospheric winds, leading to further increase in TCO by
12--16 DU over broad regions extending from east China toward the northern
Japan Sea via South Korea. Meteorological analysis also showed the
precedence of the stratospheric intrusion ahead of the development of
cyclones in the middle and lower troposphere. 相似文献
993.
In recent years, export value-added tax (VAT) refund rebate and export tax (EVRRET) measures have been adopted for energy-intensive products in China. They are proclaimed to be climate policy, yet there is no explicit and unique carbon cost set on export, and the implicit export carbon tax rates vary dramatically across sectors and over different periods. A method is provided to introduce an explicit and unique carbon cost into the current EVRRET. By setting a comparable carbon cost (US$20/tCO2 and US$30/tCO2) for eight major energy-intensive sectors to which the EVRRET is widely applied, it derives the corresponding ad valorem average rate for each sector. The introduction of a carbon cost into export VAT refund rebate policy would not increase the current export VAT refund rebate rate (except for the chemical sector), but would simply define a ceiling. However, the same introduction into the export tax policy would lead to an overall increase in sectoral export tax rates. In terms of competitiveness and World Trade Organisation concerns, the better option for introducing a carbon cost into Chinese exports would be through reforming export VAT refund rebate policy. 相似文献
994.
利用天津近30年来的逐年电力负荷数据以及2002-2005年逐时电力负荷资料,分析了天津电力负荷的变化特征,研究了电力负荷与气象因子的关系.结果表明:近30年来,天津电力负荷的长期趋势基本受当地GDP的影响,气温等气象因子的作用不明显;在季节和日尺度上,气温的影响十分显著,7、8月气温每上升1℃,气象负荷将增加120MW左右;除气温的影响外,夏季、初秋相对湿度对电力负荷的影响非常显著,此外,4月、6月、7月和12月还得考虑风的影响;一般来说,夏季最高气温在30℃以上,平均相对湿度大于65%时,才可能出现极端电力负荷. 相似文献
995.
996.
In this study, the impacts of the tropical Pacific–Indian Ocean associated mode (PIOAM) on Madden–Julian Oscillation (MJO) activity were investigated using reanalysis data. In the positive (negative) phase of the PIOAM, the amplitudes of MJO zonal wind and outgoing longwave radiation are significantly weakened (enhanced) over the Indian Ocean, while they are enhanced (weakened) over the central and eastern Pacific. The eastward propagation of the MJO can extend to the central Pacific in the positive phase of the PIOAM, whereas it is mainly confined to west of 160°E in the negative phase. The PIOAM impacts MJO activity by modifying the atmospheric circulation and moisture budget. Anomalous ascending (descending) motion and positive (negative) moisture anomalies occur over the western Indian Ocean and central-eastern Pacific (Maritime Continent and western Pacific) during the positive phase of the PIOAM. The anomalous circulation is almost the opposite in the negative phases of the PIOAM. This anomalous circulation and moisture can modulate the activity of the MJO. The stronger moistening over the Indian Ocean induced by zonal and vertical moisture advection leads to the stronger MJO activity over the Indian Ocean in the negative phase of the PIOAM. During the positive phase of the PIOAM, the MJO propagates farther east over the central Pacific owing to the stronger moistening there, which is mainly attributable to the meridional and vertical moisture advection, especially low-frequency background state moisture advection by the MJO’s meridional and vertical velocities. 相似文献
997.
Climate Dynamics - Characteristics of boreal summer intraseasonal oscillation (BSISO) over the western Pacific in ENSO decaying summer are revealed in this study. BSISO activity over the western... 相似文献
998.
Yue Li D. Conway Yanjuan Wu Qingzhu Gao S. Rothausen Wei Xiong Hui Ju Erda Lin 《Climatic change》2013,119(3-4):891-904
This study addresses the role of climate variability in the livelihoods of agricultural communities in Ningxia, Northwest China. Data sources comprise meteorological observations and official reports, complemented by questionnaires and focus group discussions designed around a livelihoods framework. Sample villages were located in three different agricultural systems: irrigated, mixed irrigated/grazing, and rainfed. Much of Ningxia is perennially dry and this is a significant limiting factor to agricultural production in the region, exacerbated by drought and buffered by irrigation mainly supplied from the Yellow River. Climate observations show stable temperatures from the 1950s to the 1980s followed by a positive trend (0.38°C/decade 1961–2010). Precipitation shows very modest trends and low decadal variability. Recent climate variability, particularly a drought from 2004–2006, was perceived to have had a significant effect on agricultural production and access to water, but it was not the only challenge respondents had faced. Susceptibility to drought was higher in the mixed irrigated and grazing and rainfed areas, due to farmers’ greater exposure to climatic hazards and because a higher proportion of their income originated from farming activities. Respondents were using a wide range of measures to retain and enhance soil moisture and maintain agricultural production. The discussion examines challenges in disentangling the role of climate within rapidly changing livelihood systems. 相似文献
999.
Climate change can bring positive and negative effects on Chinese agriculture, but negative impacts tend to dominate. The annual mean surface temperature has risen about 0.5–0.8 °C. The precipitation trends have not been identified during the past 100 years in China, although the frequency and intensity of extreme weather/climate events have increased, especially of drought. Water scarcity, more frequent and serious outbreaks of insects and diseases, and soil degradation caused by climate change have impacted agro-environmental conditions. However, temperature rise prolonged the crop growth seasons and cold damages have reduced in Northeast China. The projection of climate change indicates that the surface temperature will continue to increase with about 3.9 to 6.0 °C and precipitation is expected to increase by 9 to 11 % at the end of 21st century in China. Climate warming will provide more heat and as a consequence, the boundary of the triple-cropping system (TCS) will extend northwards by as much as 200 to 300 km, from the Yangtze River Valley to the Yellow River Basin, and the current double-cropping system (DCS) will move to the central part of China, into the current single cropping system (SCS) area which will decrease in SCS surface area of 23.1 % by 2050. Climate warming will also affect the optimum location for the cultivation of China’s main crop varieties. If no measures are taken to adapt to climate changes, compared with the potential yield in 1961–1990, yields of irrigated wheat, corn and rice are projected to decrease by 2.2–6.7 %, 0.4 %–11.9 % and 4.3–12.4 % respectively in the 2050s. Climate warming will enhance potential evaporation and reduce the availability of soil moisture, thus causing a greater need for agricultural irrigation, intensifying the conflict between water supply and demand, especially in arid and semi-arid areas of China. With adequate irrigation, the extent of the reduction in yield of China’s corn and wheat can be improved by 5 % to 15 %, and rice by 5 % or so than the potential yield in 1961–1990. Adaptive measures can reduce the agricultural loss under climate change. If effective measures are taken in a timely way, then climate change in the next 30–50 years will not have a significant influence on China’s food security. 相似文献
1000.