全文获取类型
收费全文 | 3889篇 |
免费 | 282篇 |
国内免费 | 430篇 |
专业分类
林业 | 496篇 |
农学 | 289篇 |
基础科学 | 501篇 |
758篇 | |
综合类 | 1985篇 |
农作物 | 56篇 |
水产渔业 | 160篇 |
畜牧兽医 | 189篇 |
园艺 | 49篇 |
植物保护 | 118篇 |
出版年
2024年 | 48篇 |
2023年 | 102篇 |
2022年 | 189篇 |
2021年 | 158篇 |
2020年 | 150篇 |
2019年 | 195篇 |
2018年 | 99篇 |
2017年 | 207篇 |
2016年 | 222篇 |
2015年 | 179篇 |
2014年 | 260篇 |
2013年 | 210篇 |
2012年 | 286篇 |
2011年 | 291篇 |
2010年 | 270篇 |
2009年 | 214篇 |
2008年 | 180篇 |
2007年 | 213篇 |
2006年 | 208篇 |
2005年 | 169篇 |
2004年 | 156篇 |
2003年 | 122篇 |
2002年 | 67篇 |
2001年 | 64篇 |
2000年 | 56篇 |
1999年 | 36篇 |
1998年 | 34篇 |
1997年 | 27篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 12篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1978年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有4601条查询结果,搜索用时 0 毫秒
81.
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
82.
Intrusion detection system is an essential component of network security protection mechanisms. Most intrusion detection system can not adapt the variation of network environment. Aiming at this problem, an adaptive strategy that composed of condition space and strategy space is proposed. The condition space describes the network environment and the strategy space describes the strategy. There is an exclusive strategy corresponds to a certain environment state in condition space. On the base of the adaptive strategy, an adaptive intrusion detection system based on agent and data mining is designed. The simulation experiments indicate that the adaptive strategy is effective. 相似文献
83.
Larger quantities of data about flight performance and flight condition are recorded by flight data recorder (FDR) during the aircraft's flying. It is an importance task to make 3D flying animation from the data on the process of flight data. The design ideas and realizing methods about the software of flying animation system driven by the data from relation database are presented. 相似文献
84.
Data warehouse is not the simply data accumulation of operational database. For exerting the function of data warehouse, the construction of data warehouse should be convenient for the data mining and business intelligent work, supply information access, analyze, and share for decision maker. The key to constructing a successful data warehouse is to fully understand the demand of end users from beginning to the end, search and storage data surround users motive closely. This paper first analyzes the data warehouse characteristic and the sort of data component, emphasizes in effective data loading methods and strategies from operational database to data warehouse, gives five sorts data loading methods. 相似文献
85.
86.
This article puts forward a 3 Layers Model for the communication between embedded system and PC. It is based on the speciality of them and the TCP/IP model. The model defines the communicate process of embedded system to be three layers: Transport Layer, Control Layer and Application Layer. Each layer serves for its higher-up. It can keep the efficiency and credibility of the communicate process and the authors prove and analyse that in the article. the concept of the model is also suitable for Bluetooth, IrDA and other kinds of communication about embedded system. 相似文献
87.
Bill of material of product is data about product structure, and plays an important role in product information management. The paper analyzed characteristics of product BOM, and put forward a product BOM management method based on single layer BOM, witch can well meet requirements of product BOM. 相似文献
88.
用ImageWare实现缺损点云的曲面重构 总被引:1,自引:0,他引:1
针对有缺损的点云数据,提出了在逆行工程软件ImageWare平台下进行曲面重构的途径;介绍了运用逆向工程技术进行CAD模型设计的操作流程;用平行面截取点云数据,拟合出曲线线条;通过对曲线条的桥接,利用完整的曲线条重构出曲面。 相似文献
89.
车辆行驶记录仪及研究现状 总被引:1,自引:0,他引:1
概述了车辆行驶记录仪的原理、组成和功能,介绍了国内外车辆行驶记录仪的发展以及应用情况,阐述了现有记录仪的缺陷和不足,并对记录仪的发展趋势进行了展望。 相似文献
90.
针对任意查询区域年度现状地类面积统计困难、长时序变更流量分析计算耗时等问题,提出基于时空变化图模型的统计优化方法。运用图的连通性原理,对查询统计区域内和边界处的要素实体进行分类,实现了时序快照统计优化算法,解决了任意查询区域时点现状统计困难的问题,提高了时序快照统计的效率。运用多商品流原理进行时空网络图约化性判定,实现了变更流量统计优化算法,减少了要素空间叠置分析次数,解决了长时序土地利用变化变更流量统计耗时问题,提高了统计的效率。最后,以2009—2012年琼海市土地利用数据为例,进一步验证优化算法的有效性和可行性。 相似文献