全文获取类型
收费全文 | 1201篇 |
免费 | 64篇 |
国内免费 | 90篇 |
专业分类
林业 | 79篇 |
农学 | 66篇 |
基础科学 | 76篇 |
97篇 | |
综合类 | 603篇 |
农作物 | 79篇 |
水产渔业 | 43篇 |
畜牧兽医 | 180篇 |
园艺 | 85篇 |
植物保护 | 47篇 |
出版年
2024年 | 6篇 |
2023年 | 17篇 |
2022年 | 57篇 |
2021年 | 56篇 |
2020年 | 55篇 |
2019年 | 50篇 |
2018年 | 33篇 |
2017年 | 49篇 |
2016年 | 42篇 |
2015年 | 49篇 |
2014年 | 65篇 |
2013年 | 72篇 |
2012年 | 94篇 |
2011年 | 99篇 |
2010年 | 96篇 |
2009年 | 87篇 |
2008年 | 65篇 |
2007年 | 71篇 |
2006年 | 77篇 |
2005年 | 64篇 |
2004年 | 40篇 |
2003年 | 16篇 |
2002年 | 18篇 |
2001年 | 32篇 |
2000年 | 28篇 |
1999年 | 10篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1956年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有1355条查询结果,搜索用时 125 毫秒
51.
云计算在中小企业信息化中的应用研究 总被引:1,自引:0,他引:1
云计算是继网格计算后又一项正在兴起中的技术,它的出现使"互联网上众多的计算机成为一台虚拟超级计算机"的梦想逐渐变成了现实。概述了云计算的概念与原理,阐明了云计算在中小企业中实施的技术与优势,提出了云计算在中小企业实施中存在的问题以及解决问题的策略。 相似文献
52.
全文彬 《信阳农业高等专科学校学报》2004,14(2):103-104
信阳市苗木生产发展迅速,但仍存在着品种单一、结构不合理、缺少品牌优势、科技含量低等问题。应采取统一规划、合理种植、因地制宜等技术措施,促进信阳市苗木生产的可持续发展。 相似文献
53.
文章首先分析了浙江省温州市机插的现状,指出加快突破插秧机械化技术瓶颈,已成为推进水稻生产全程机械化,实现农业现代化的重要主攻方向,要制订切实可行的水稻插秧机械化推进计划;从节省秧田、节水肥药、节本省工、高产稳产、避灾增效、五个方面阐述了机插的优势,从技术上可行、政策上有利、推广有依托、多数农民观念转变四个方面阐述了机插有利条件;最后提出推进水稻机插的对策与措施。 相似文献
54.
介绍了在曲柄压力机上切边冲孔的复合模结构设计、工作原理及装配和调试要求等. 相似文献
55.
Based on the linear strain distribution assumption, strain development of tensile bars and ultimate moment capacity of strengthening section, which strengthened on tension side with service load un removed, is investigated. It is showed that the higher the service load bending moment to original moment capacity ratio M 1k /M u1 is, the smaller the tensile strain of strengthening re barsis, and the more the amount of strengthening re barsis, the smaller the tensile strain of original re barsis. It also showed that,When original re bar area is relatively small and strengthening re bar area is adequate, both original and strengthening re bars may get yielded and a great increment in section moment capacity is achieved, even though the ration M 1k M u1 has a relatively high value. 相似文献
56.
57.
南方暖湿地区河流生态环境需水量估算 总被引:1,自引:0,他引:1
以广东省鹤山市沙坪河生态环境需水为研究对象,从河流水资源规划、开发利用过程中涉及到的生态环境需水问题出发,提出了暖湿地区河流生态环境需水量计算的方法,并计算了各项生态环境需水的数量和比例。其中:基本生态环境需水量0.79 m3/s;水面蒸发需水量0.05 m2/s;输沙需水量0.70 m3/s;稀释净化污染物需水量1.10 m3/s;水土保持需水量1.00 m3/s。沙坪河生态环境需水总量3.64 m3/s,总生态环境需水量约占地表径流总量的38.6%,成果可用于水资源规划与开发利用。 相似文献
58.
Single-lap-joint adhesively bonded metal specimen which is the national standard experimental method in use has an extremely non-uniform distribution of shear stresses along the joint, and tensile stress concentration of high values is produced on the steel substrate interfaces. Therefore the test result, which is not the real bonding shear strength between adhesive and steel substrates, can only be used as a test index for qualities of adhesives not the strength criterion for load is capacity evaluation. The combined bonding disc specimen is adopted for measuring bonding shear properties of adhesive on steel substrates, has a very uniform distribution of shear stresses in adhesive and along the bonding surfaces of steel substrates, of which the uniform coefficient is greater than 0.97. Furthermore, when adhesive joint is treated as an arc and steel substrates are chamfered at both ends of the joint, tensile stresses on the bonding surfaces can be reduced to less than 20 MPa which can hardly cause tensile failure. Thus, the results of combined bonding disc specimens can actually represent the real bonding shear strength or bonding shear-compression strength between adhesive and steel substrates, which can be used as strength criterion for load capacity evaluation of bonding members. 相似文献
59.
This paper takes Sulige Gas Field as a case study and used three methods including laboratory experiments,production performance analysis and reservoir simulation to study the influence of stress sensitivity on production of fractured tight gas wells.The results show that the fracture length and conductivity of hydraulically created fracture are reduced more than 50%,and the stress sensitivity of hydraulically created fracture is stronger than that of matrix.With the increase of gas production,the influence of stress sensitivity becomes stronger,and finally results in 18% reduction of gas production,and hydraulically created fractures play an important role in the influence of stress sensitivity. 相似文献
60.