全文获取类型
收费全文 | 3664篇 |
免费 | 369篇 |
国内免费 | 458篇 |
专业分类
测绘学 | 1439篇 |
大气科学 | 216篇 |
地球物理 | 685篇 |
地质学 | 1215篇 |
海洋学 | 245篇 |
天文学 | 24篇 |
综合类 | 382篇 |
自然地理 | 285篇 |
出版年
2024年 | 26篇 |
2023年 | 58篇 |
2022年 | 69篇 |
2021年 | 104篇 |
2020年 | 120篇 |
2019年 | 112篇 |
2018年 | 97篇 |
2017年 | 152篇 |
2016年 | 145篇 |
2015年 | 163篇 |
2014年 | 224篇 |
2013年 | 278篇 |
2012年 | 281篇 |
2011年 | 289篇 |
2010年 | 181篇 |
2009年 | 212篇 |
2008年 | 227篇 |
2007年 | 287篇 |
2006年 | 265篇 |
2005年 | 221篇 |
2004年 | 189篇 |
2003年 | 183篇 |
2002年 | 133篇 |
2001年 | 103篇 |
2000年 | 76篇 |
1999年 | 72篇 |
1998年 | 54篇 |
1997年 | 29篇 |
1996年 | 30篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有4491条查询结果,搜索用时 15 毫秒
971.
972.
973.
974.
Yuan‐Sen Yang Shang‐Hsien Hsieh Keh‐Chyuan Tsai Shiang‐Jung Wang Kung‐Juin Wang Wei‐Choung Cheng Chuan‐Wen Hsu 《地震工程与结构动力学》2007,36(15):2291-2306
An Internet‐based framework, named Internet‐based Simulation for Earthquake Engineering (ISEE) was developed to facilitate collaborative earthquake engineering experiments performed by multiple laboratories in a network environment. One of the approaches in the ISEE framework, named Database Approach, offers an easy way to perform multi‐site networked collaborative pseudo‐dynamic experiments. The Database Approach uses the Structured Query Language (SQL), a common and standardized computer language used in database management systems, for inter‐laboratory communications. Using the SQL protocol, it is easy to monitor the experiments' progress, access the data, as well as develop additional programs to expand the functions for a networked experiment. This approach offers consistency and durability of selected experimental data both during and after experiments. Two networked pseudo‐dynamic experiments were conducted to demonstrate the feasibility and expansibility of the Database Approach in ISEE. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
975.
A.?PerrinEmail author C.?Puzzarini J.-M.?Colmont C.?Verdes G.?Wlodarczak G.?Cazzoli S.?Buehler J.-M.?Flaud J.?Demaison 《Journal of Atmospheric Chemistry》2005,51(2):161-205
In order to investigate the upper troposphere/lower stratosphere (UTLS) region of the earth's atmosphere, ESA/ESTEC (European
space agency) is considering the opportunity to develop the spaceborne limb sounding millimeter sensor “MASTER” (millimeter
wave acquisitions for stratosphere/troposphere exchange research). This instrument is part of the “atmospheric composition
explorer for chemistry and climate interactions” (ACECHEM) project. In addition, ESA/ESTEC is developing the “MARSCHALS” (millimeter-wave
airborne receiver for spectroscopic characterization of atmospheric limb sounding) airborne instrument which will demonstrate
the feasibility of MASTER. The present paper describes the line-by-line database which was generated in order to meet at best
the needs of the MASTER (or MARSCHALS) instrument. The linelist involves line positions, line intensities, line broadening
and line shift parameters in the 294–305, 316–325, 342–348, 497–506 and 624–626 GHz spectral microwindows. This database was
first generated for the target molecules for MASTER (H2O, O3, N2O, CO, O2, HNO3, HCl, ClO, CH3Cl, BrO). In addition, ten additional molecules (SO2, NO2, OCS, H2CO, HOCl, HCN, H2O2, COF2, HO2 and HOBr) had also to be considered in the database as “possible interfering species” for the retrieval of the target molecules
of MASTER. The line parameters were derived, depending on their estimated accuracy, (i) from a combination of spectral parameters
included in the JPL and HITRAN catalogs (ii) from data taken into the literature or (iii) using data obtained through experimental
measurements (and/or) calculations performed during the present study. 相似文献
976.
Abnormally high-priced transactions in urban land speculation bring detrimental effects on economy, environment, and society. Governmental agencies around the world are striving hard to monitor and control land speculation by introducing various policy objectives and tools for an efficient urban development planning. One of the major challenges in controlling land speculation is to quickly identify the spatiotemporal locations of concern (hot spots) by monitoring the spatial clustering pattern changes over time and to alert the appropriate decision-making agencies for timely policy intervention. In this paper, we introduce a framework to rapidly detect the spatiotemporal hot spots of speculative land transactions in near-real-time data by exploiting the prospective monitoring procedures. We applied this method in the city of Hwasung, Republic of Korea, as an empirical illustration and found that the locations Jeongnam, Bongdam, Mado, and Dongtan were identified as hot spots with high, concentrated transaction values. The results indicate that the proposed framework is a capable tool for capturing prospective temporal indicators and pinpointing the localities of land speculation. 相似文献
977.
978.
979.
980.
由于GML所采用的层次模型与关系模型之间存在重大差异,传统的关系模型不适合半结构化的GML数据的存储.针对该问题,本文从本原XML数据库(NXD)的角度,对GML空间数据存储问题进行了研究.首先分析了NXD的特征及其相对于XED的优势,然后对当前主流NXD的优缺点进行分析与比较,结合GML的特点,选用eXist对GML... 相似文献