全文获取类型
收费全文 | 2688篇 |
免费 | 138篇 |
国内免费 | 186篇 |
专业分类
林业 | 604篇 |
农学 | 202篇 |
基础科学 | 132篇 |
244篇 | |
综合类 | 1288篇 |
农作物 | 107篇 |
水产渔业 | 71篇 |
畜牧兽医 | 241篇 |
园艺 | 45篇 |
植物保护 | 78篇 |
出版年
2024年 | 17篇 |
2023年 | 59篇 |
2022年 | 86篇 |
2021年 | 86篇 |
2020年 | 92篇 |
2019年 | 110篇 |
2018年 | 49篇 |
2017年 | 104篇 |
2016年 | 100篇 |
2015年 | 87篇 |
2014年 | 185篇 |
2013年 | 157篇 |
2012年 | 239篇 |
2011年 | 231篇 |
2010年 | 176篇 |
2009年 | 137篇 |
2008年 | 144篇 |
2007年 | 165篇 |
2006年 | 161篇 |
2005年 | 101篇 |
2004年 | 99篇 |
2003年 | 72篇 |
2002年 | 66篇 |
2001年 | 29篇 |
2000年 | 36篇 |
1999年 | 30篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 23篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 25篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有3012条查询结果,搜索用时 15 毫秒
71.
72.
新疆乌什县国家级公益林分级区划落界浅析 总被引:1,自引:0,他引:1
分析新疆鸟什县国家级公益林分级区划界定情况,总结取得的成就,并就分级区划界定过程中存在的问题,提出对策和建议。 相似文献
73.
在网络技术迅速发展的今天,图书馆传统的服务模式已经无法满足读者对文献信息资源的需求。文章论述了数字环境下图书馆的发展变化和图书馆开展服务创新的必要性,以西安音乐学院图书馆《西北民族音乐学术资源数据库》的建设为例,阐述了音乐院校图书馆改变传统服务观念,为师生提供主动服务、知识服务的工作实践。 相似文献
74.
75.
76.
《Journal of Sustainable Forestry》2013,32(1-2):305-320
Summary The goal of this paper is to describe recent attempts to define the stewardship concept and to translate it into action on the ground. The focus is on national forest lands and the unique challenges federal land managers face in working with the public to implement a concept that has different meanings to a variety of stakeholders. Stewardship requires more flexibility than is often found under existing administrative authorities. Large, bureaucratic agencies face many barriers in applying creative and innovative solutions to existing problems, not the least of which are internal and external reward structures. While there exist some authorities that allow for the creative testing of stewardship contracting projects on the ground, a number of challenges remain. Two significant ones are: (1) the need for a clearer, consistent understanding (by both Forest Service employees and constituents) of the authorities that can be used to test stewardship concepts; and (2) a more broad-based agreement on the desired outcome of stewardship projects. Given the current lack of understanding and agreement on how to implement stewardship concepts, the most effective means of moving the issue forward will be to apply innovative tests of contracting methods under current or new temporary authorities. These tests should be designed, implemented, monitored, and evaluated using broad-based, inclusive, on-the-ground coalitions that create effective ties and linkages between local and national levels. 相似文献
77.
78.
现代电气照明是一门技术与艺术相结合的学科。照明设计作为照明技术成果的体现,是完成各种照明设施的手段,它不仅涉及照明理论,光源研究、照明器研制、建筑设计及色彩调配、灯光分布等工程内容,更强调照明生理学及照明心理学。故在设计中应力求达到上述要求,并注意整体效果及艺术效果。 相似文献
79.
DENG Hua LI Hui YANG Hong ZHOU Zhaohai LIANG Haozhao XU Zhigao WU Fuda LI Qiaofeng HUANG Luqi 《畜牧兽医学报》1956,51(11):2836-2848
To study the clinicopathology and histopathology of African swine fever (ASF), and to explore the internal relationship between pathological changes and disease occurrence and development and its pathological mechanism, 13 Landrace pigs with bodyweight about 20 kg were intramuscular injected with African swine fever virus (ASFV), strain Pig/HLJ/18 at a dose of 102HAD50·mL-1. During the experiment, all the dead pigs were systematically dissected and sampled, paraffin sections were produced, and haematoxylin-eosin staining was performed. Clinicopathological evaluation standards for acute ASF were established, then pathological lesions (classification variables) were expressed by counting frequency and percentage, and the lesion degree (continuous variables) was graded and scored according to different pathological changes of various tissues and organs. The results showed that all infected pigs were in line with the clinical characteristics of ASF, including acute, febrile and highly infectious, with a 100% incidence rate and 100% mortality. The dead pigs showed typical characteristics of septicemia, cadavers prone to corruption, blood clotting adverse or hemolysis, rigor mortis incomplete. The main pathological lesions were hemorrhagic necrotizing lymphadenitis, acute inflammatory splenomegaly (septic spleen), cerebral edema, pulmonary edema and lung consolidation et al. The spleen and lymphonodus are the target organs attacked by ASFV, with the most significant lesions, the earliest occurrence time, the longest duration and the highest frequency. The most prominent pathological changes are blood circulation disorders, including multiple pathological manifestations such as edema, hyperemia, congestion, hemorrhage, infarction, disseminated intravascular coagulation (DIC), and the most important characteristics are hemorrhagic lesions. The inflammatory reaction of lymphocytic exudation caused by ASFV runs through the whole process, especially in the middle and later stages of the course. The results suggest that the main pathological process of acute African swine fever is a typical immune/inflammatory cascade reaction and severe systemic blood circulation disorder, which resulted in the high incidence rate and high mortality rate of acute ASF. 相似文献
80.
<机械制图>是农业工程工科类学科的一门重要的技术基础课程.在新的形势下,它面临着几个比较突出的问题.笔者对其进行了分析,并在多年实践教学的基础上,提出了自己的见解与解决思路,它在提高教学效率、强化技能训练、增强"标准"意识及知识的教、学系统化方面收到了良好效果. 相似文献