全文获取类型
收费全文 | 6638篇 |
免费 | 260篇 |
国内免费 | 290篇 |
专业分类
林业 | 85篇 |
农学 | 247篇 |
基础科学 | 535篇 |
721篇 | |
综合类 | 5267篇 |
农作物 | 117篇 |
水产渔业 | 4篇 |
畜牧兽医 | 114篇 |
园艺 | 60篇 |
植物保护 | 38篇 |
出版年
2024年 | 15篇 |
2023年 | 52篇 |
2022年 | 99篇 |
2021年 | 114篇 |
2020年 | 151篇 |
2019年 | 143篇 |
2018年 | 64篇 |
2017年 | 175篇 |
2016年 | 224篇 |
2015年 | 258篇 |
2014年 | 438篇 |
2013年 | 385篇 |
2012年 | 577篇 |
2011年 | 694篇 |
2010年 | 581篇 |
2009年 | 575篇 |
2008年 | 594篇 |
2007年 | 556篇 |
2006年 | 392篇 |
2005年 | 277篇 |
2004年 | 144篇 |
2003年 | 156篇 |
2002年 | 58篇 |
2001年 | 54篇 |
2000年 | 61篇 |
1999年 | 33篇 |
1998年 | 46篇 |
1997年 | 61篇 |
1996年 | 33篇 |
1995年 | 35篇 |
1994年 | 25篇 |
1993年 | 31篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有7188条查询结果,搜索用时 468 毫秒
101.
《Journal Of Agricultural & Food Information》2013,14(2-3):125-143
ABSTRACT Identifying the best source of information to satisfy the needs of local clientele has always been the challenge facing collection development and instruction librarians. In order to provide users with the best possible access tool and source for comprehensive information, it is important that librarians be aware of the most productive sources of information in a field. This paper identifies where the bulk of agricultural economics research is published and indexed. It also ascertains whether Google Scholar is as productive in covering this information as CAB Abstracts and EconLit. The cited reference counts for the top 50 cited sources in Web of Knowledge and Google Scholar are also compared. The scatter of the journal literature in this field, based on the Library of Congress Subject Headings, is also provided. The study identified a broad range of article scattering in areas where agricultural economics and agribusiness materials are published. On the cited reference count, Google Scholar was as productive as the Web of Knowledge. Google Scholar is a free source of very useful information for cited references and other subject searches in the area of agricultural economics and could be used to complement traditional databases. 相似文献
102.
《Communications in Soil Science and Plant Analysis》2012,43(1-2):81-100
Abstract Differential thermogravimetry (DTG), differential scanning calorimetry (DSC), and stepwise thermogravimetry (STG), together with two acid hydrolysis methods (hydrolysis with hydrochloric acid in a single step, and hydrolysis with sulfuric acid in two steps), were evaluated to determine the quality of four plant materials (Medicago sativa, Eucalyptus globulus, Quercus ilex, and Pinus halepensis) before and after mixing with a red earth. These quality indices were then compared with the same materials in the field, whether their decomposition could be predicted. All the thermal methods gave poor results. In both DTG and DSC, the presence of the mineral matrix gave rise to strong distortions in the spectra. Since the spectrum of any mixture is not simply the sum of the spectra of the two components (organic matter + mineral matter), these distortions could not be corrected by simply subtracting the spectrum of the red earth alone. STG trials also gave poor results, because the presence of the mineral matrix greatly increased the quality indices, and reduced the ability of the method to distinguish between organic matter qualities. In view of our results, the usefulness of thermal methods in the characterization of soil organic matter would seem to be restricted to certain organic horizons (L, F, and perhaps H). In contrast, methods based on acid hydrolysis were comparatively more satisfactory. Their resolution (ability to distinguish organic matter qualities) was much higher than that of thermal methods. However, they were able to distinguish carbon more accurately than nitrogen. The sulfuric acid method, unlike the hydrochloric acid method, was affected by the presence of a mineral matrix. While both methods could be improved, in their present form they seem to operate as good predictors of carbon and nitrogen mineralization. 相似文献
103.
分析福建省莆田市涵江区农产品质量安全工作取得的成绩和存在的问题,从提升全区的农产品质量安全水平的角度,提出对策建议。 相似文献
104.
"发展经济学"创始人张培刚1945年的博士论文《农业与工业化》,是近代农业机械化理论之集大成者。由于社会和历史的原因,这一农业机械化理论宝库一直未被认真开发、应用于我国农业机械化的实践,以致走了不少弯路。随着一代经济学大师的离世,如今,挖掘、开发这一理论宝库,用之培养新型农业机械化人才,指导我国农机化实践,必将结出丰硕之果。 相似文献
105.
阐述基本实现农业机械化应坚持的基本思想;明确了基本实现农业机械化的内涵、标志和评价指标体系建立的基本原则;初步构建了评价体系的基本框架。 相似文献
106.
针对农业期刊中插图存在的不规范等问题,提出了论文插图应具有自明性、示意性、简洁性和规范性的一般要求。还提出,要做好科技论文的插图,需要编辑、作者、排版人员做好规范、修改、美术等3道"关口",插图的质量就能大幅提高。 相似文献
107.
Suyang Agricultural Resource Development Bureau 《农机具之友》2010,(3):42-43,30
沐阳县颜集贯勤虞姬花木合作社,实现了农民在市场经济条件下的联合和合作,由过去的松散式产业经营创新发展到目前的利益紧密型产业化经营,提高了农民的组织化程度,改变了农民在市场经济中的弱势地位。给农民带来了实实在在的经济利益,增强了农民抗御市场风险的能力。 相似文献
108.
109.
张弘 《吉林农业科技学院学报》2012,(4):117-119
依据多媒体教学的特点,重新对一般高校设置的课程进行了划分。在分析目前高校多媒体教学应用情况的基础上,提出了基于教学内容开展多媒体教学的建议。 相似文献
110.
以KTA框架为原理,分析了农业科技人员知识转移的重要性,在此基础上提出了知识转移的具体路径,即从知识源、知识接受者和转移媒介3个方面对农业科技人员的知识转移提出建议。 相似文献