全文获取类型
收费全文 | 1954篇 |
免费 | 100篇 |
国内免费 | 308篇 |
专业分类
林业 | 258篇 |
农学 | 188篇 |
基础科学 | 423篇 |
419篇 | |
综合类 | 741篇 |
农作物 | 41篇 |
水产渔业 | 30篇 |
畜牧兽医 | 213篇 |
园艺 | 21篇 |
植物保护 | 28篇 |
出版年
2024年 | 8篇 |
2023年 | 39篇 |
2022年 | 54篇 |
2021年 | 57篇 |
2020年 | 43篇 |
2019年 | 74篇 |
2018年 | 49篇 |
2017年 | 72篇 |
2016年 | 83篇 |
2015年 | 80篇 |
2014年 | 97篇 |
2013年 | 93篇 |
2012年 | 150篇 |
2011年 | 126篇 |
2010年 | 140篇 |
2009年 | 124篇 |
2008年 | 97篇 |
2007年 | 130篇 |
2006年 | 126篇 |
2005年 | 108篇 |
2004年 | 114篇 |
2003年 | 77篇 |
2002年 | 63篇 |
2001年 | 53篇 |
2000年 | 40篇 |
1999年 | 44篇 |
1998年 | 35篇 |
1997年 | 32篇 |
1996年 | 25篇 |
1995年 | 25篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1981年 | 1篇 |
1978年 | 4篇 |
排序方式: 共有2362条查询结果,搜索用时 15 毫秒
21.
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
22.
The exact computing of house architectural area and apportionment of area is strongly related to the actual interests of people. If it is done manually,there are many problem such as longer time spending, more workload, requiring detailed verification, nonstandard calculating report. Using ActiveX automation and ADO techniques, the house architectural area computing and plotting system was developed under Autocad R14 environment with VB 6.0 and Access database in order to solve above problem. The developed system can automatically compute house architectural area and apportionment of area for each floor of each building and can print the related data report and drawing. The system works well in many departments of house measurement. Several key technical problem of the system are discussed. 相似文献
23.
Based on the principles of operational risk measurement provided by Basel II,the paper discusses the problem of operational risk correlations among different business lines / risk types.The correlation coefficients between the aggregate losses among different business lines / risk types are calculated.Copula arithmetic is put forward to compute correlation coefficients matrix of aggregate losses.Besides,the result is used to calculate the capital requirement of operational risk. 相似文献
24.
The engineering contract is composed of many documents between client and contractor, such as agreement, notification of award, tender and appendix to bid, conditions for particular application, instruction to bidders, technical specifications, design drawings and bill of quantities etc. Because of the limited time and money to prepare these documents, the defect is unavoidable. The defects include omittance, equivocalness, conflict and mistake. These defects often lead to claims. 相似文献
25.
The implement of enterprise knowledge management gives rise to extensive research on its measurement. Based on the existing measurement theories and evaluation index systems of enterprise knowledge management during the past three years in China, this paper analyzes the problems in measuring target and designing the evaluation index system in the existing research findings, and explains detailedly why measurement target of enterprise knowledge management should be "level evaluation" instead of "performance evaluation", and definitely points out the meanings of enterprise knowledge management level and significance of its evaluation. This paper also indicates that the design of the evaluation index system should be complete, reasonable, proper and operable. 相似文献
26.
JIA Yan-yan 《保鲜与加工》2004,(2):106-109
In this paper, the problems of bringing natural resources and environmental condition into accounting are discussed and lay emphasis on object measurement, imaging and disclosure in accounting report of environmental accounting. The author suggests that the environmental accounting is the necessary production of global economy for sustainable development in modern society; it is also a new ecological accounting subject formed by the result of environmental economies and accounting penetrating into each other. As a contribution of accounting circles to sustainable development, environmental accounting has become a hot topic in recent years. 相似文献
27.
28.
29.
30.
种子含水率在线测量系统 总被引:5,自引:0,他引:5
根据种子含水率的测量要求,研制了一种可同时测量电容、质量和温度3个参量的装置和测量电路。该测量系统的机械装置由2个同心圆筒组成,内筒的旋转运动实现被测种子的动态喂料。采用抗寄生电容效应的开关电容电路测量上、下极板之间的电容;下极板同时也是称量平台;温度传感器测量种子的温度。3个测量值经A/D转换电路以数字量输出。分别用3个电路单独测量已知的电容、质量和温度,以及不同温度和相对湿度条件下对电容测量值的影响,并据此分析了各测量单元的精度、可靠性和可行性。 相似文献