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991.
锚固系统质量检测的小波分析法 总被引:6,自引:2,他引:4
波动方程的有限元数值解表明,对锚杆灌浆体内部缺陷的探测,可用声速、幅值、波形等声参数作为判断的依据。基于小波包分析得到的能量特征向量,可以作为缺陷特征向量进行无损检测。人工神经网络这类非线性动力学系统运用于该灰色系统的质量预测,可取得良好的效果。 相似文献
992.
993.
鄂尔多斯地区退耕还林造林模式研究 总被引:3,自引:2,他引:1
通过对鄂尔多斯地区退耕还林造林模式的研究,在造林技术方面总结出先进适用又符合当地实际的造林模式。其中,①风沙区造林模式:旱柳、柠条防风固沙林,杨树、沙柳、柠条防风固沙林,柠条、紫穗槐防风固沙林;②丘陵沟壑区造林模式:油松+沙棘,沙棘+柠条,油松+山杏;③干旱硬梁区造林模式:柠条两行一带式植苗造林、旱柳、沙柳防风固沙林、榆树、柠条防风固沙林,取得了显著成效。造林实践表明,3a后保存率达100%,造林成活率大于70%的造林面积准格尔旗占84%、鄂托克旗占82%,生长状况优良。说明采用的造林模式是成功的,可以直接指导退耕还林等项目的建设和可供毗邻地区生产造林借鉴。 相似文献
994.
995.
华北中部岩石圈电性结构——应县—商河剖面大地电磁测深研究 总被引:13,自引:0,他引:13
20 0 1年, 沿着山西应县到山东商河, 重新布置大地电磁测深剖面进行研究.采用现代先进的大地电磁数据处理技术和快速松弛二维反演方法获得该剖面二维电性结构模型, 从而充分展示了华北地区岩石圈电性结构的特点.从电性特征上讲, 华北岩石圈以太行山前断裂为界划分为东、西两区, 东区为低阻区, 西区为高阻区.在东区, 上地壳电性结构基本与华北裂谷系的隆、坳构造格局相对应, 岩石圈的电导最高达3× 104 S, 远远大于强烈活动的安第斯山岩浆弧区和西藏高原岩石圈的电导.这里, 在构造连接部位的地壳中有不连续的高导体存在, 电导率大约0.1~ 0.8S/m.在西区, 太行山和恒山的岩石圈为高阻块体, 表现出稳定大陆区岩石圈导电性结构的特点.但恒山高阻块体之下发现一组向西缓倾的高导层, 其电导率为0.0 4~0.2 5S/m, 顶面在2 0km深处, 底面深度大约40km. 相似文献
996.
“数字福建”及“数字闽东南”的构建与应用 总被引:2,自引:0,他引:2
余明 《地球信息科学学报》2003,5(2):32-35
本文介绍“数字福建”建设发展状况及实施目标和任务,结合闽东南地区数字化、网络化、可视化和智能化问题,提出闽东南可持续发展的几点建议。建设“数字闽东南”就是要实现闽东南区域网络平台集成、应用系统集成和信息资源集成的电子化、数字化和智能化。 相似文献
997.
998.
Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version le (B0Z) and the other B1Z based on B0Z and heterogeneously-treated by ‘combined approach’ , were coupled to the meso-scale model MM4, respectively. Through the calculations of equations from the companion paper, parameters representing land surface heterogeneity and suitable for the coupling models were found out. Three cases were simulated for heavy rainfalls during 36 hours, and the sensitivity of short-term weath-er modeling to the land surface heterogeneity was tested. Through the analysis of the simulations of the three heavy rainfalls, it was demonstrated that B1Z, compared with B0Z, could more realistically reflect the features of the land surface heterogeneity, therefore could more realistically reproduce the circulation and precipitation amount in the heavy rainfall processes of the three cases. This shows that even short-term weather is sensitive to the land surface heterogeneity, which is more obvious with time passing, and whose influence is more pronounced in the lower layer and gradually extends to the middle and upper layer. Through the analysis of these simulations with B1Z, it is suggested that the bulk effect of smaller-scale fluxes (i.e., the momentum, water vapor and sensible heat fluxes) near the significantly-heterogeneous Land surface is to change the larger-scale (i.e., meso-scale) circulation, and then to influence the development of the low-level jets and precipitation. And also, the complexity of the land-atmosphere interaction was shown in these simulations. 相似文献
999.
The influences of boundary layer parameterization schemes on mesoscale heavy rain system 总被引:2,自引:0,他引:2
1.Introducti0nThemesoscaleoperationalmodel-whichisoftenused,isMM4orMM5'butMM4isusedfrequentlyonlO3kmscale.Thephysicalprocessesinthismodeldevelopconstantly.FororiginalMM4,thecomputationofsurfacefluxesisnotaccurate,andKmodelfortheturbu-lencefluxesbetweenany2levelsneedstobeimprovedbynewtreatment.Inordertostudytheinfluencesofboundarylayerparameterizationschemesonmesoscaleheavyrainsystem,sur-facefluxesandKmodelinoriginalMM4areimprovedbytherecentresearchinthispaPer.Theflux-profilerelationsforv… 相似文献
1000.
A method based on Giorgi (1997a, 1997b) and referred to as ‘combined approach’, which is a combination of mosaic approach and analytical-statistical-dynamical approach, is proposed. Compared with those of other approaches, the main advantage of the combined approach is that it not only can represent both interpatch and intrapatch variability, but also cost less computational time when the land surface heterogeneity is considered. Because the independent variable of probability density function (PDF) is extended to the single valued function of basic meteorological characteristic quantities, which is much more universal, the analytical expressions of the characteristic quantities, (e.g., drag coefficient, snow coverage, leaf surface aerodynamical resistance) affected by roughness length are derived, when the roughness length (and/ or the zero plane displacement) heterogeneity has been mainly taken into account with the approach. On the basis of the rule which the PDF parameters should follow, we choose a function y of the roughness length z0 as the PDF independent variable, and set different values of the two parameters width ratio αn and height ratio γ of PDF (here a linear, symmetric PDF is applied) for sensitivity experiments, from which some conclusions can be drawn, e.g., relevant characteristic terms show different sensitivities to the heterogeneous characteristic (i.e., roughness length), which suggests that we should consider the heterogeneities of the more sensitive terms in our model instead of the heterogeneities of the rest, and which also implies that when the land surface scheme is coupled into the global or regional atmospheric model, sensitivity tests against the distribution of the heterogeneous characteristic are very necessary; when the parameterαn is close to zero, little heterogeneity is represented, andαn differs with cases, which have an upper limit of about 0.6; in the reasonable range ofαn, a peak-like distribution of roughness length can be depicted by a small value ofγ, etc.. 相似文献