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531.
Ⅰ.INTRODUCTION We have discovered that there exists a good corresponding relationship between theanomalous axes of soil temperature at a depth of 1.6m in winter (December to February) andprecipitations in following flood season (Tang et al., 1982a). We have also designed a simplethermodynamical model and applied it to the forecasting of precipitations in the flood season(Tang et al., 1982 b,c). The practical forecast started from 1975. Before 1980, however, therewere only 40-50 stations in China for measuring the soil temperature at a 1.6m depth. Since1980, the stations have been increased to a total of about 180, but no available mean valueshad been obtained from newly added stations before 1982. Therefore the analysis and map-ping of anomalies of soil temperature was not performed until 1983, and from then on theprecision of analysis has been greatly improved. The following is the actual situation of forecast in five years from 1983 to 1987. 相似文献
532.
北半球夏季全球热带和副热带200hPa平均辐散环流的研究 总被引:7,自引:5,他引:7
大气的运动场或风场包括两部分:一是旋转部分,另一是辐散部分。虽然旋转部分的方差占总运动场方差的大部分(约占80%),但与辐散风相联系的垂直环流对于天气系统的发展是重要的。Krishna-murti等人最早研究了全球热带的辐散环流。最近他的研究表明,辐散风场的大部分是属于纬向的行星尺度垂直环流的水平分支,这意味着行星尺度系统总是热力直接环流,并且以纬向环流为主。Van der Boogard计算了7月多年平均的速度势场,发现对流层上层最强的辐散中心在中南半岛上空。 相似文献
533.
534.
The probability of received-power fluctuation in the turbulent atmosphere is discussed with a simple and yet reasonable model for a direct-detection optical system. Good agreement was found between the theore-tical results and the field experiment. Thus the analysis in this paper may be taken as a guide for the design of atmospheric optical system. 相似文献
535.
通过对胶东牟平-乳山地区1:2.5万航空甚低频电磁异常的分析研究,并结合航磁,航放、遥感以及区域构造地质资料,进行了构造地质填图,首次进一步证实了被前人所忽视的近东西向断裂构造的存在,并给予了准确定位。在此基础上进行了金矿成矿远景预测,取得了比较满意的效果。 相似文献
536.
This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with 39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene. 相似文献
537.
Jian Sheng 《Climate Dynamics》1995,12(2):125-140
The Madden-Julian oscillation (MJO) simulated by the Canadian Climate Centre general circulation model (CCC GCM) is identified
by a principal oscillation pattern (POP) analysis and compared with that observed in the real atmosphere. The results are
based upon two integrations of the CCC GCM, one with a parameterization of penetrative cumulus convection (EXP1) and the other
with a moist convective adjustment scheme (EXP2). The signal of MJO can be detected in both integrations as the first POP
of the 200 hPa velocity potential along the equator. The disturbances show a distinctive wave number one structure with the
strongest local amplitude found in the longitudes corresponding to the region of the Asian monsoon. The phase speed of the
eastward wave propagation is higher in the eastern Pacific and lower in the monsoon region where the convective activities
are strongest. These features are in good agreement with the observations. The energy spectrum of the velocity potential peaks
at the frequency corresponding to a period of about 38 days for EXP1, which is somewhat shorter compared to the observed periods
of 40–50 days. On the other hand, two spectral peaks can be clearly identified for EXP2, one with a period of 24 days and
the other with a much longer period, somewhere near 112 days. Both peaks appear statistically significant at 95% level. Long
term data of the observed atmosphere show little indication of such spectral separation. The horizontal patterns identified
by the POP analysis resemble to some extent the baroclinic response of tropical flow to a heat source travelling with the
speed of MJO. At the upper level, Rossby wave energy propagates westward with winds generally following the height contours,
whereas Kelvin wave energy propagates to the east from the heat source with strong cross-contour flow near the equator. At
the lower level, the patterns are essentially reversed. The model-generated precipitation and diabatic heating are examined
by compositing against the moving MJO. It is found in EXP2 that the composite heating distribution is coherent with the flow
pattern only in a certain sector of the equator, depending on whether the fast or slow mode is used to determine the reference
point. The composite vertical heating profile of a slower mode tends to have a maximum found at a lower level. The sensitivity
of simulated MJO to the cumulus convection scheme in the model is discussed.
Received: 19 December 1994 / Accepted: 11 July 1995 相似文献
538.
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
539.
540.
Carbon Storage in Terrestrial Ecosystems of China: Estimates at Different Spatial Resolutions and Their Responses to Climate Change 总被引:20,自引:1,他引:19
Jian Ni 《Climatic change》2001,49(3):339-358
The carbon storage of terrestrial ecosystems in China was estimated using acommon carbon density method for vegetation and soils relating to thevegetation types. Usingmedian density estimates, carbon storage of 35.23 Gt (1 Gt = 1015g) in biomass and119.76 Gt in soils with total of 154.99 Gt were calculated based on thebaseline distribution of37 vegetation types. Total carbon storage of the median estimates at differentspatial resolutionswas 153.43, 158.08 and 158.54 Gt, respectively, for the fine (10),median (20) and coarse (30)latitude × longitude grids. There were differences of –1.56, +3.09and +3.55 Gt carbon storagebetween baseline vegetation and those at different spatial resolutions. Changein mappingresolution would change area estimates and hence carbon storage estimates. Thefiner the spatialresolution in mapping vegetation, the closer the carbon storage to thebaseline estimation. Carbonstorage in vegetation and soils for baseline vegetation is quite similar tothat of biomes predictedby BIOME3 for the present climate and CO2 concentration of 340ppmv. Climate changealone as well as climate change with elevated CO2 concentrationwill produce an increasein carbon stored by vegetation and soils, especially a larger increase in thesoils. Total mediancarbon storage of terrestrial ecosystems in China will increase by 5.09 Gt and15.91 Gt for theclimate scenario at CO2 concentration of 340 ppmv and 500 ppmv,respectively. This ismainly due to changes in vegetation areas and the effects of changes inclimate and CO2concentration. 相似文献