全文获取类型
收费全文 | 7891篇 |
免费 | 599篇 |
国内免费 | 1798篇 |
专业分类
安全科学 | 678篇 |
废物处理 | 381篇 |
环保管理 | 649篇 |
综合类 | 3980篇 |
基础理论 | 1843篇 |
环境理论 | 1篇 |
污染及防治 | 1538篇 |
评价与监测 | 515篇 |
社会与环境 | 479篇 |
灾害及防治 | 224篇 |
出版年
2024年 | 26篇 |
2023年 | 124篇 |
2022年 | 368篇 |
2021年 | 356篇 |
2020年 | 366篇 |
2019年 | 258篇 |
2018年 | 371篇 |
2017年 | 416篇 |
2016年 | 434篇 |
2015年 | 392篇 |
2014年 | 406篇 |
2013年 | 491篇 |
2012年 | 893篇 |
2011年 | 688篇 |
2010年 | 439篇 |
2009年 | 364篇 |
2008年 | 393篇 |
2007年 | 364篇 |
2006年 | 388篇 |
2005年 | 589篇 |
2004年 | 679篇 |
2003年 | 536篇 |
2002年 | 188篇 |
2001年 | 163篇 |
2000年 | 129篇 |
1999年 | 99篇 |
1998年 | 55篇 |
1997年 | 53篇 |
1996年 | 45篇 |
1995年 | 52篇 |
1994年 | 28篇 |
1993年 | 28篇 |
1992年 | 27篇 |
1991年 | 23篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1984年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
Foraging desert ants, Cataglyphis fortis, encounter different sequences of visual landmarks while navigating by path integration. This paper explores the question whether the storage of landmark information depends on the context in which the landmarks are learned during an ant's foraging journey. Two experimental set-ups were designed in which the ants experienced an artificial landmark panorama that was placed either around the nest entrance (nest marks) or along the vector route leading straight towards the feeder (route marks). The two training paradigms resulted in pronounced differences in the storage characteristics of the acquired landmark information: memory traces of nest marks were much more robust against extinction and/or suppression than those of route marks. In functional terms, this result is in accord with the observation that desert ants encounter new route marks during every foraging run but always pass the same landmarks when approaching the nest entrance. 相似文献
95.
Population differences in anti-predator behaviour have been demonstrated in several species, although less is known about the genetic basis of these traits. To determine the extent of genetic differences in boldness (defined as exploration of a novel object) and shoaling within and between zebrafish (Danio rerio) populations, and to examine the genetic basis of shoaling behaviour in general, we carried out a study that involved laboratory-raised fish derived from four wild-caught populations. Controlling for differences in rearing environment, significant inter-population differences were found in boldness but not shoaling. A larger shoaling experiment was also performed using one of the populations as the basis of a North Carolina type II breeding design (174 fish in total) to estimate heritability of shoaling tendency. A narrow-sense heritability estimate of 0.40 was obtained, with no apparent dominance effects. 相似文献
96.
97.
98.
M.?A.?de?FigueiredoEmail author D.?M.?Reiner H.?J.?Herzog 《Mitigation and Adaptation Strategies for Global Change》2005,10(4):647-657
This paper examines how legal standards of liability may apply to geologic carbon storage. The liability regime governing
geologic carbon storage will shape the technology's cost-effectiveness and overall attractiveness. We classify potential sources
of liability into operational, in situ, and climate liability. As a first step, we explore in situ liability in the United States. After summarizing legal standards of liability including negligence, breach of implied warranty,
strict liability, and product liability, we discuss how liability may be addressed at the level of the federal government,
state government, industry, and the firm. Finally, we address the implications of judicial treatment of liability for carbon
storage, including the apportionment of liability and the adequacy of current regulations. 相似文献
99.
100.
河南省黄河湿地生态旅游资源的开发与保护研究 总被引:1,自引:0,他引:1
河南黄河湿地旅游资源丰富,有各具特色的湿地景观、复杂多样的生物景观、丰富的地文景观、悠久的历史人文景观和工程园林景观等多种景观类型;但目前存在着开发利用程度较低,市场营销不够、景点开发质量不高,旅游设备简陋、基础设施落后,景点少、点热面冷,人才缺乏、经营管理水平低等众多问题;最后从旅游功能分区、旅游开发、旅游管理、旅游线路设计、旅游环境监测、区域旅游联合、加大宣传力度等方面提出了河南黄河湿地生态旅游资源开发的对策. 相似文献