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1.
《Marine Geodesy》2013,36(3-4):147-157
On 7 December 2001, Jason-1 was successfully launched by a Boeing Delta II rocket from the Vandenberg Air Force Base, California. The Jason-1 satellite will maintain the high accuracy altimeter service provided since 1992 by TOPEX/Poseidon (T/P), ensuring the continuity in observing and monitoring the Ocean Dynamics (intraseasonal to interannual changes, mean sea level, tides, etc.). Despite one-fourth the mass and power, the Jason-1 system has been designed to have basically the same performance as T/P, measuring sea surface topography at a centimetric level. This new CNES/NASA mission also provides near real-time data for sea state and ocean forecast. The first two months of the Jason-1 mission have been dedicated to the assessment of the overall system. The goals of this assessment phase were: 1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES); 2. To verify that platform performance requirements are met with respect to Jason-1 requirements; 3. To verify that payload instruments performance requirements evaluated at instrument level are met; 4. To assess the performance of the Jason-1 Ground System. This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products.  相似文献   
2.
王璐玮  汪涛  张晗 《地理研究》2021,40(12):3314-3332
构建显示性比较优势指数,分析“走出去”全球化下中国医药产业的国际竞争力;识别企业战略连接类型,分析“引进来”全球化下生物医药全球生产网络(GPN)与本土创新网络(IIN)间的战略耦合过程;运用超效率SBM模型,测度GPN-IIN战略耦合目标实现的达成效率,并从静、动态视角探究其时空变化的原因。发现:① 中国医药产业通过转口、代加工进入北美市场的难度加大,东盟、金砖国家成为其重要的出口对象,与欧盟加强贸易有助于其形成高标准的自由贸易协定网络。② 2000—2006年,多数外商直接投资(FDI)企业形成“两头在外”的产业布局,在GPN中处于被俘虏地位,大多内资企业学习能力不足,处于IIN边缘。2007—2013年,部分FDI企业由GPN价值链末端向高端转移,部分内资企业由IIN边缘向核心转移,但转移过程中具有强松脚性。2014—2019年,GPN-IIN战略耦合克服上一阶段嵌入不足、松脚性等问题,两者间的关系通道日益增多和稳固。③ GPN-IIN耦合绩效经历了“大分散、小集聚→简单结构孕育→局部结构构建→级联秩序分异”的演变,在此过程中技术进步对其促进效果最强,规模效率次之,纯技术效率最弱。而限制其提升的主要原因从价值链低端锁定、企业类型晋升不足向企业类型退化冗余、社会关系松弛,再向境外业务拓展乏力、资本-技术脱钩过渡。  相似文献   
3.
中国地球气候系统模式的发展及其模拟和预估   总被引:4,自引:0,他引:4  
地球气候系统模式是开展多学科、多圈层集成研究的重要平台,其发展是国际地学领域特别是全球变化领域竞争的前沿。中国的地球气候系统模式研发工作始于20世纪80年代,最近10年得到快速发展。研发格局上已经形成中国科学院、有关部委和高校三足鼎立的局面。文中在简要回顾中国地球气候系统模式早期发展历史的基础上,总结了中国参加第6次耦合模式比较计划的9个地球气候系统模式的技术特点,初步评估了中国4个模式对全球和东亚气候模拟的基本性能,分析了其在4种共享社会经济路径情景下对全球降水与温度的预估变化及其与平衡态气候敏感度的联系。最后,结合国际态势,从发展的角度提出未来中国气候模式研发工作需要加强的8个方向。   相似文献   
4.
A generalized additive model (GAM) was used to model the spatial distribution of snow depth in the central Spanish Pyrenees. Statistically significant non‐linear relationships were found between distinct location and topographical variables and the average depth of the April snowpack at 76 snow poles from 1985 to 2000. The joint effect of the predictor variables explained more than 73% of the variance of the dependent variable. The performance of the model was assessed by applying a number of quantitative approaches to the residuals from a cross‐validation test. The relatively low estimated errors and the possibility of understanding the processes that control snow accumulation, through the response curves of each independent variable, indicate that GAMs may be a useful tool for interpolating local snow depth or other climate parameters. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
5.
Upgrading noncode conforming buildings to mitigate seismic induced damages is important in moderate to high seismic hazard regions. The damage, can be mitigated by using conventional (e.g. FRP wrapping) and emerging (e.g. smart structures) retrofit techniques. A model for the structure to be retrofitted should include relevant performance indicators. This paper proposes a variable stiffness smart structure device known as the Smart Spring to be integrated on building structures to mitigate seismic induced damage. The variable stiffness capability is of importance to structures that exhibit vertical (e.g. soft storey) irregularities and to meet different performance levels under seismic excitation. To demonstrate the utility of the proposed retrofitting technique, a four‐storey steel building is modelled in MATLAB and appropriate performance indicators are chosen. Various return period seismic hazards are generated from past earthquake event records to predict the structure's performance. The performance improvement because of the retrofitting of building structures using the variable stiffness device is presented. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
6.
A web‐based methodology for the prediction of approximate IDA curves, which consists of two independent processes, is proposed. The result of the first process is a response database of the SDOF model, whereas the second process involves the prediction of approximate IDA curves from the response database by using n‐dimensional linear interpolation. Such an approach enables user‐friendly prediction of the seismic response parameters with high accuracy. In order to demonstrate the capabilities of the proposed methodology, a web application for the prediction of the approximate 16th, 50th and 84th fractile responses of an RC structure was developed. For the presented case study, the response database was computed for a set of 30 ground motion records and the discrete values of six structural parameters. Very good agreement between the computed and the approximated IDA curves of the four‐storey RC building was observed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
7.
Tilapia rendalli is a predominately macrophagous fish. However, it was able to colonise an oligotrophic dam (Flag Boshielo) with limited macrophytes. Therefore, the diet of T. rendalli in this dam was investigated; its stomach contents were examined over 12 months. A size related dietary shift was evident. Juveniles fed mainly on zooplankton while sub-adult and adult fish grazed on both macrophytes and marginal vegetation. T. rendalli’s ability to strive in an environment with limited food resources led to a subsequent study to determine its aquaculture potential. Its growth performance was compared to that of the commonly cultured Oreochromis mossambicus. Juveniles of both species were fed a commercial tilapia diet for 60 days. Specific growth rate and protein efficiency ratio was comparable to that of O. mossambicus (P > 0.05, ANOVA). Feed conversion ratio was significantly higher (P < 0.05) in T. rendalli (1.43) than in O. mossambicus (1.25) indicating a better efficiency in feed utilisation by O. mossambicus. At a physiological level, protease, lipase and cellulase activities did not differ significantly between the two fish species (P > 0.05). Amylase activities were significantly higher (P < 0.05) in T. rendalli than in O. mossambicus. The highest amylase activities were recorded in the proximal intestines as 26.34 and 22.00 μmol/min/mg protein in T. rendalli and O. mossambicus respectively. This may be an indicator that T. rendalli is better equipped to digest plant diets. T. rendalli may be the aquaculture species of choice for emerging fish farmers who cannot afford the highly priced fishmeal as a protein source in fish diets.  相似文献   
8.
程金华  马冬 《安徽地质》2013,(2):108-111,115
赋存于中元古代大谷运组上段地层中的绩溪县洪坑板岩类砚石,通过与歙砚石~歙县龙头石及江西龙尾石、九江石、大畈石、玉山石的物理化学参数测试资料对比分析,歙砚石其原岩均为泥砂质构造沉积岩,但岩性、成分、物理化学性能特征存在一定差异,与歙砚石—龙尾石属于不同成因机制的砚石。  相似文献   
9.
In a companion paper, an overview and problem definition was presented for ground motion selection on the basis of the conditional spectrum (CS), to perform risk‐based assessments (which estimate the annual rate of exceeding a specified structural response amplitude) for a 20‐story reinforced concrete frame structure. Here, the methodology is repeated for intensity‐based assessments (which estimate structural response for ground motions with a specified intensity level) to determine the effect of conditioning period. Additionally, intensity‐based and risk‐based assessments are evaluated for two other possible target spectra, specifically the uniform hazard spectrum (UHS) and the conditional mean spectrum (CMS, without variability).It is demonstrated for the structure considered that the choice of conditioning period in the CS can substantially impact structural response estimates in an intensity‐based assessment. When used for intensity‐based assessments, the UHS typically results in equal or higher median estimates of structural response than the CS; the CMS results in similar median estimates of structural response compared with the CS but exhibits lower dispersion because of the omission of variability. The choice of target spectrum is then evaluated for risk‐based assessments, showing that the UHS results in overestimation of structural response hazard, whereas the CMS results in underestimation. Additional analyses are completed for other structures to confirm the generality of the conclusions here. These findings have potentially important implications both for the intensity‐based seismic assessments using the CS in future building codes and the risk‐based seismic assessments typically used in performance‐based earthquake engineering applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
10.
The self‐centering energy dissipative (SCED) brace is a new steel bracing member that provides both damping to the structure and a re‐centering capability. The goal of this study was to confirm the behavior of SCED braces within complete structural systems and to confirm the ability to model these systems with both a state‐of‐the‐art computer model as well as a simplified model that would be useful to practicing engineers. To these ends, a three‐story SCED‐braced frame was designed and constructed for testing on a shake table. Two concurrent computer models of the entire frame were constructed: one using the opensees nonlinear dynamic modeling software, and a simplified model using the commercial structural analysis software sap2000 . The frame specimen was subjected to 12 significant earthquakes without any adjustment or modification between the tests. The SCED braces prevented residual drifts in the frame, as designed, and did not show any significant degradation due to wear. Both numerical models were able to predict the drifts, story shears, and column forces well. Peak story accelerations were overestimated in the models; this effect was found to be caused by the absence of transitions at stiffness changes in the hysteretic model of the braces. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
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