全文获取类型
收费全文 | 6586篇 |
免费 | 254篇 |
国内免费 | 1405篇 |
专业分类
林业 | 715篇 |
农学 | 904篇 |
基础科学 | 1151篇 |
1536篇 | |
综合类 | 2715篇 |
农作物 | 336篇 |
水产渔业 | 219篇 |
畜牧兽医 | 372篇 |
园艺 | 145篇 |
植物保护 | 152篇 |
出版年
2024年 | 91篇 |
2023年 | 196篇 |
2022年 | 311篇 |
2021年 | 362篇 |
2020年 | 314篇 |
2019年 | 312篇 |
2018年 | 223篇 |
2017年 | 324篇 |
2016年 | 365篇 |
2015年 | 317篇 |
2014年 | 419篇 |
2013年 | 464篇 |
2012年 | 545篇 |
2011年 | 497篇 |
2010年 | 454篇 |
2009年 | 411篇 |
2008年 | 386篇 |
2007年 | 420篇 |
2006年 | 330篇 |
2005年 | 317篇 |
2004年 | 217篇 |
2003年 | 191篇 |
2002年 | 133篇 |
2001年 | 84篇 |
2000年 | 68篇 |
1999年 | 76篇 |
1998年 | 65篇 |
1997年 | 49篇 |
1996年 | 58篇 |
1995年 | 35篇 |
1994年 | 39篇 |
1993年 | 39篇 |
1992年 | 30篇 |
1991年 | 29篇 |
1990年 | 24篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有8245条查询结果,搜索用时 15 毫秒
61.
INVITED REVIEW—IMAGE REGISTRATION IN VETERINARY RADIATION ONCOLOGY: INDICATIONS,IMPLICATIONS, AND FUTURE ADVANCES
下载免费PDF全文
![点击此处可从《Veterinary radiology & ultrasound》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yang Feng Jessica Lawrence Kun Cheng Dean Montgomery Lisa Forrest Duncan B. Mclaren Stephen McLaughlin David J. Argyle William H. Nailon 《Veterinary radiology & ultrasound》2016,57(2):113-123
The field of veterinary radiation therapy (RT) has gained substantial momentum in recent decades with significant advances in conformal treatment planning, image‐guided radiation therapy (IGRT), and intensity‐modulated (IMRT) techniques. At the root of these advancements lie improvements in tumor imaging, image alignment (registration), target volume delineation, and identification of critical structures. Image registration has been widely used to combine information from multimodality images such as computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) to improve the accuracy of radiation delivery and reliably identify tumor‐bearing areas. Many different techniques have been applied in image registration. This review provides an overview of medical image registration in RT and its applications in veterinary oncology. A summary of the most commonly used approaches in human and veterinary medicine is presented along with their current use in IGRT and adaptive radiation therapy (ART). It is important to realize that registration does not guarantee that target volumes, such as the gross tumor volume (GTV), are correctly identified on the image being registered, as limitations unique to registration algorithms exist. Research involving novel registration frameworks for automatic segmentation of tumor volumes is ongoing and comparative oncology programs offer a unique opportunity to test the efficacy of proposed algorithms. 相似文献
62.
基于"3S"技术的甘肃子午岭自然保护区土地利用变化研究 总被引:1,自引:0,他引:1
以甘肃省子午岭自然保护区为研究对象,运用"3S"技术,对研究区的地形图、不同时相的TM遥感影像进行数据预处理,并分类提取了研究区2个时段的土地利用信息.对分类信息进行统计分析后并与实地调查数据进行比较,结果表明,近20年来甘肃子午岭自然保护区的森林覆盖面积在稳步提高,乔木林面积明显增加.为甘肃子午岭自然保护区工程的建设提供了基础信息,为林区植物种群生长及分布调查研究提供了宏观数据,并且输出了研究区不同时相土地利用专题图. 相似文献
63.
本文介绍了欧盟、美国和日本评估加工农产品中农药残留的数据要求和试验准则,以及开展膳食摄入风险评估和推荐农药最大残留限量(MRL)的方法,汇总了用于农药残留评估的加工农产品及其分类,分析了加工农产品中农药MRL制定现状,为进一步提高我国相关领域技术提供借鉴。比较分析结果表明,欧盟和美国在农药登记资料要求中明确提出了加工试验数据要求并且制定了相应的试验准则,美国在试验准则中描述了加工农产品中农药MRL的推荐原则;美国和日本制定了一定数量的加工农产品中农药MRL,欧盟建立了适用于监管农药MRL的加工因子数据库;欧盟、美国和日本均在相关法规中规定了加工农产品中农药残留的合规性判定。 相似文献
64.
65.
The high-speed access for medical digital image sequences was restricted to special device and complicated system in the past. The authors present a new method of high-speed access for medical digital image sequences which can be performed on general computer by means of the combination of Serial ATA(SATA) and Redundant Array of Independent Disk(RAID).Then they introduce the scheme of system configuration and software program. Lastly the testing result is given and the speediness,cheapness and conveniency of this method are elucidated. 相似文献
66.
67.
The colored patterns on arbitrary cut plane is an important method in 3D data-field visualization of finite element.By using the technology of the Object-Oriented Programming and the method of scan-line,the colored patterns on arbitrary cut plane are given.The example by the OPENGL of Visual C++ R6 can support the theory satisfactorily. 相似文献
68.
69.
Zeag Yongning Tong Fu 《保鲜与加工》1989,(2):43-49
An optimization approach for multi-relational joins based on
the matching concept in graph theory is introduced. The basic idea lies in constructing a join graph from an expression of N-relation query, and seeking for a maximun matching with minimun total weight. The algorithm for bipartition(X, Y) is proposed in this paper. 相似文献
70.
Intelligent recognition system of gun code is designed , which achieves online recognition of gun code. We applied video camera to get image, and some special technique in this deformed character recognition. As well, we applied dynamic template matching to get a better result. 相似文献