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51.
STUDY ON GIS FOR YIELD ESTIMATION BY REMOTE SENSING IN JILIN MAIZE BELTSTUDYONGISFORYIELDESTIMATIONBYREMOTESENSINGINJILINMAIZ...  相似文献   
52.
Estimates of AGN Black Hole Mass and Minimum Variability Timescale   总被引:4,自引:0,他引:4  
Black hole mass is one of the fundamental physical parameters of active galactic nuclei (AGNs), for which many methods of estimation have been proposed. One set of methods assumes that the broad-line region (BLR) is gravitationally bound by the central black hole potential, so the black hole mass can be estimated from the orbital radius and the Doppler velocity. Another set of methods assumes the observed variability timescale is determined by the orbital timescale near the innermost stable orbit around the Schwarzschild black hole or the Kerr black hole, or by the characteristic timescale of the accretion disk. We collect a sample of 21 AGNs, for which the minimum variability timescales have been obtained and their black hole masses (Mσ) have been well estimated from the stellar velocity dispersion or the BLR size-luminosity relation. Using the minimum variability timescales we estimated the black hole masses for 21 objects by the three different methods, the results are denoted by Ms, Mk and Md, respectively. We compared each of them with Mσindividually and found that: (1) using the minimum variability timescale with the Kerr black hole theory leads to small differences between Mσand Mk, none exceeding one order of magnitude, and the mean difference between them is about 0.53 dex; (2) using the minimum variability timescale with the Schwarzschild black hole theory leads to somewhat larger difference between Mσand Ms: larger than one order of magnitude for 6 of the 21 sources, and the mean difference is 0.74 dex; (3) using the minimum variability timescale with the accretion disk theory leads to much larger differences between Mσand Md, for 13 of the 21 sources the differences are larger than two orders of magnitude; and the mean difference is as high as about 2.01 dex.  相似文献   
53.
周琪  李平衡  王权  郑超磊  徐璐 《中国沙漠》2014,34(1):98-107
涡度相关仪通量值所代表的通量贡献区范围,对于通量观测塔的选址、仪器安装高度的确定以及通量观测数据的质量控制等具有重要的指导意义。利用通量贡献区模型对位于古尔班通古特沙漠试验场通量观测资料的空间代表性进行初步分析。结果表明:该荒漠区在大气稳定条件下90%的通量贡献区最远可以达到686.40 m,通量贡献函数最大点的位置在162.50 m;大气稳定时各风向的通量贡献区范围在生长末期均达到最大,生长初期和中期的源区变化因受到各风向风速和植被下垫面的影响而有差异;大气不稳定时不同生长时期各风向通量贡献区没有固定变化规律;通量源区大约有58.71%的信息来自于荒漠区通量观测塔西南至西北方,整个生长季生长末期通量贡献最多,所占比例为40.16%。由FSAM模型测得的通量贡献区范围可以较准确地反映荒漠生态系统下垫面的通量信息。  相似文献   
54.
We have performed a statistical study of the properties of the broadband continuum of Narrow Line Seyfert 1 galaxies (NLS1s) by collecting ratio,infrared, optical and X-ray continuum data from various databases and comparedthe results with control samples of Broad Line Seyfert 1 galaxies (BLSls). We findthat the fraction (~ 6%) of Radio Loud (RL) NLSls is significantly less than thatof BLS1s (~ 13%), which is caused by the lack of radio-very-loud sources in theformer. The rarity of RL NLS1s, especially radio-very-loud ones, is consistent withthe scenario of small black hole and high accretion rate for NLSls. Six new radio loudNLSls are found and five RL NLS1 candidates are presented. In comparison withthe BLS1s, the NLS1s tend to have stronger far infrared emission, cooler infraredcolors and redder B- K color, which suggests that NLS1s are hosted by dust-richernuclei. The NLS1s also show steeper soft X-ray spectrum and large soft X-rayto optical flux ratio, while a significant fraction show fiat soft X-ray spectra. Atleast two factors can account for this, absorption and spectral variability. We alsoperform a correlation analysis between various broad band data. It is found thatmost correlations identified for NLS1s are also valid for radio quiet BLS1s: (1) theoptical colors are anti-correlated with X-ray spectral index; (2) higher optical, X-ray and NIR luminosity objects show bluer optical colors and red H - K color; (3)higher luminosity objects show warmer IRAS color; (4) the radio loudness correlateswith B - K and X-ray to optical flux ratio. Radio loud objects behave somewhatdifferently in a few correlations.  相似文献   
55.
With the rapid development of the marine economy industry, human exploitation of marine resources is increasing, which is contributing to the growing trend of eutrophication and frequent occurrence of red tide. Accordingly, investigations of seawater quality have attracted a great deal of attention. This study was conducted to construct a seawater environmental quality assessment model based on the variable fuzzy recognition model. The uncertainty and ambiguity of the seawater quality assessment were then considered, combining the monitoring values of evaluation indicators with the standard values of seawater quality. Laizhou Bay was subsequently selected for a case study. In this study, the correct variable model for different parameters was obtained according to the linear and nonlinear features of evaluation objects. Application of the variable fuzzy recognition model for Laizhou Bay, water quality evaluation and comparison with performance obtained using other approaches revealed that the generated model is more reliable than traditional methods, can more reasonably determine the water quality of various samples, and is more suitable for evaluation of a multi-index, multi-level, nonlinear marine environment system; accordingly, the generated model will be an effective tool for seawater quality evaluation.  相似文献   
56.
In deep mineral exploration, the acquisition of audio magnetotelluric (AMT) data is severely affected by ambient noise near the observation sites; This near-field noise restricts investigation depths. Mathematical morphological filtering (MMF) proved effective in suppressing large-scale strong and variably shaped noise, typically low-frequency noise, but can not deal with pulse noise of AMT data. We combine compressive sensing and MMF. First, we use MMF to suppress the large-scale strong ambient noise; second, we use the improved orthogonal match pursuit (IOMP) algorithm to remove the residual pulse noise. To remove the noise and protect the useful AMT signal, a redundant dictionary that matches with spikes and is insensitive to the useful signal is designed. Synthetic and field data from the Luzong field suggest that the proposed method suppresses the near-source noise and preserves the signal well; thus, better results are obtained that improve the output of either MMF or IOMP.  相似文献   
57.

安徽铜陵新桥矿区二叠系栖霞组底部和石炭系黄龙组—船山组之间产出层状、似层状菱铁矿矿层。开展菱铁矿矿层成因研究对于深入剖析区域层控矽卡岩型铜铁矿床成矿机制具有重要意义。本文利用粉晶X射线衍射(XRD)、扫描电镜(SEM)对菱铁矿矿石进行矿物学研究,结果发现菱铁矿矿石主要由菱铁矿、石英、伊利石和有机质等组成,菱铁矿颗粒粒径较小,表面具有成岩自生的自形石英硬模的微结构,SEM原位微区成分分析显示菱铁矿中除了主量元素铁,还含有大量的锰、锌和钙。矿石中存在两种微结构和不同成因的石英:表面具菱铁矿硬模和次生加大结构的碎屑石英;具六方双锥、单锥以及生物成因球形的自生石英。菱铁矿矿石的组成和矿物表面微结构表明其为沉积成因,非岩浆热液起源。富有机质和亚铁的沉积菱铁矿层和沉积胶状黄铁矿层协同作用,可能是铜陵地区乃至长江中下游成矿带层状铜铁矿床层控性重要制约因素,以及可能作为燕山期中酸岩浆演化的氧化性含铜成矿流体卸载成矿的地球化学还原障。

  相似文献   
58.
根据249个表层沉积物样品的Ca,Al,N,P,Mg,Fe,Mn,Ti和有机碳的测定数据,利用稳健RQ型主分量分析及Q型聚类分析方法,对珠江口外陆架表层沉积物进行了地球化学分类,并将该陆架区划分成陆源细碎屑沉积区、经叠加改造的残留泥砂质沉积区、生物碎屑沉积区以及高能环境下的石英砂质沉积区。结果表明了稳健统计方法相对于传统统计方法的优越性,以及采用稳健主分量的Q载荷进行聚类分析相对于用原始变量进行聚类分析的优越性。  相似文献   
59.
裴春传  曾琴 《天文学报》1998,39(1):103-105
使用紫金山天文台青海观测站13.7米毫米波射电望远镜,于1996年12月10日至1997年1月2日和1997年3月25日至1997年4月4日对海尔-波普彗星的CO分子J=1—0转动跃迁谱线(频率为115.27120GHz)进行了观测.观测谱线表明,CO分子相对于地心的速度比彗星整体相对于地心的速度要小些,即有蓝移现象.这反映了CO分子是由该彗星迎着太阳的面以一定的速度产生出来的.从观测谱线中还初步估算了该彗星CO分子的产生速率.  相似文献   
60.
小良试验站三种植被类型地表径流效应的对比研究   总被引:13,自引:0,他引:13  
周国逸  余作岳 《热带地理》1995,15(4):306-312
本文分析研究了3种植被类型下的地表径流在汇流、洪峰及径流过程上的特征,差异是巨大的。在径流过程上桉树林和裸地的变地剧烈,几乎没有什么调蓄作用,洪峰流量占一次性降水径流量的绝大部分,涨水和退水流量都较小。本文应用灰色系统GM(2,1)模型,成功地预测了以年和以月为时间尺度的地表径流序列,其预测模型可以用来对这些时间尺度的地表径流进行预报。  相似文献   
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