首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5498篇
  免费   380篇
  国内免费   444篇
林业   749篇
农学   350篇
基础科学   540篇
  860篇
综合类   2575篇
农作物   110篇
水产渔业   319篇
畜牧兽医   519篇
园艺   80篇
植物保护   220篇
  2024年   48篇
  2023年   127篇
  2022年   213篇
  2021年   208篇
  2020年   195篇
  2019年   278篇
  2018年   128篇
  2017年   259篇
  2016年   277篇
  2015年   234篇
  2014年   367篇
  2013年   341篇
  2012年   436篇
  2011年   444篇
  2010年   377篇
  2009年   312篇
  2008年   248篇
  2007年   299篇
  2006年   263篇
  2005年   216篇
  2004年   208篇
  2003年   154篇
  2002年   85篇
  2001年   102篇
  2000年   68篇
  1999年   55篇
  1998年   49篇
  1997年   46篇
  1996年   37篇
  1995年   47篇
  1994年   42篇
  1993年   35篇
  1992年   19篇
  1991年   28篇
  1990年   20篇
  1989年   21篇
  1988年   13篇
  1987年   10篇
  1986年   1篇
  1985年   1篇
  1984年   5篇
  1983年   1篇
  1982年   1篇
  1978年   2篇
  1962年   1篇
  1956年   1篇
排序方式: 共有6322条查询结果,搜索用时 62 毫秒
61.
Identification and adjustment on the disfigurements of original data of VISAR are probed by developing software for VISAR data reducing based on measure theory. Then the software is applied to plate impact experiment of ceramics. The disfigurements of light intensity data are identified and adjusted through Lissajou~ figures. The results indicate that VISAR data are reduced quickly and effectively by the software, and the exact free surface velocity history is obtained.  相似文献   
62.
Wavelets have been widely applied in such research areas as image processing, computer vision, network management and data mining. Wavelets have many favorable properties, which are hierarchical and multiresolution decomposition structure, linear time and space complexity of the transformations. The paper presents wavelet application on the algorithms of data mining, in cluding as clustering, classification, distributed data mining, similarity search, approximate query processing, visualization and so on. Finally, the paper concludes by discussing the impact of wavelets on data mining research and outlining potential future research directions and applications.  相似文献   
63.
To construct data warehouse with heterogeneous, self-governing and distributed database system is a challenge. Two problems have to be solved: one is how to collect data from heterogeneous data sources by an effective method, the other is how to clear up and change the format of the data collected from data sources. The opening and the interact-operation property of Web Services is Analyzed. A Data Collection System based on Web Services, which communicates with heterogeneous data sources with SOAP and HTTP, has been designed. A Data Collector is introduced to clear up and to transform data with composition technology. The pivotal XML technology of transforming and loading up the data are discussed.  相似文献   
64.
To the question that a meter is correspond with a set of lead and a sensor,this paper presents a design of data acquisition system for vehicle based on CAN bus.In this way,the combinatorial instrument is only connected by a bus unit.Author introduces the data acquisition structure chart and the CAN interface,analyzes the software by program flow chart,and shows it's application for vehicle virtual instrument.A method of calculating vehicle speed,engine rotate speed and the course of development mileage are also given.  相似文献   
65.
Considering the difficult of acquiring and transmission the signal from the moving equipment, a new fault diagnosis monitoring system is presented. The system acquires the state signal from the moving equipment by data acquisition module that based in W77E58 high-speed SCM, and transmits the data fast by wireless mode. The signal data can be use for fault diagnosis and precise analysis. The system has the ability for acquiring abundance of data with a high speed, the ability for high accuracy data conversion, and has a function of programme controlling gain and programme controlling low-pass filtering. The successful application of this system on the vibration monitor about the material-transporting bogie in an iron works of a domestic steel enterprise proves the stability and credibility about the design project, also testifies its practical value and versatility.  相似文献   
66.
Data Mining can distill the connotative, unknown and potential value information or pattern from many data. It is a problem that must be settled during the developing of Decision Support System how to discover knowledge from Data Warehouse. In order to realize the continuous mathematical forecast that will be used in the Marketing Decision Support System for Industrial Enterprise, the authors use the method of regression to discuss how to design the algorithm for Data Mining, how to design the model for Data Mining, and so on. When the algorithm applied to the sales forecast, the result processing to simulation data indicates it can realize the expected effect.  相似文献   
67.
68.
SVG based on XML is a kind of language describing 2D vector graphics.It is usability and applicability to set up WebGIS.The paper puts forward a system structure of WebGIS based on SVG,which has been applied to campus electronic map system of Chongqing University.It has been proved the method is feasibility and practicability.The paper sets forth some key techniques of implement of the system in detail: coding method of organizing SVG spatial data;generation of SVG electronic map;storage of SVG spatial data and implement of client.  相似文献   
69.
A developing method is given which based on object-oriented modeling techniques for management information systems.The modeling techniques,especially,from CDM to PDM conversion,make it possible that the method can be used for developing such management information systems which based on relational database.The result shows that it can raise the efficency of the system developing,improve the system tability,enhance the system maintenability.  相似文献   
70.
This paper introduces a method of solving the problem of leather cavity measurement in shoe CAD/CAM by industrial CT technology. Concentrating on peculiarity and requirement of leather cavity measurement, this paper presents a X-ray industrial CT system scheme, which not only satisfy the requirement of leather cavity measurement but also can achieve general industrial CT. measurement. The achievement on data collection system and motion control of stepping motor is emphasized.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号