全文获取类型
收费全文 | 99835篇 |
免费 | 1244篇 |
国内免费 | 1349篇 |
专业分类
安全科学 | 3933篇 |
废物处理 | 3835篇 |
环保管理 | 14884篇 |
综合类 | 21794篇 |
基础理论 | 27474篇 |
环境理论 | 75篇 |
污染及防治 | 19100篇 |
评价与监测 | 6034篇 |
社会与环境 | 4682篇 |
灾害及防治 | 617篇 |
出版年
2022年 | 872篇 |
2021年 | 871篇 |
2020年 | 687篇 |
2019年 | 910篇 |
2018年 | 1363篇 |
2017年 | 1390篇 |
2016年 | 2354篇 |
2015年 | 1898篇 |
2014年 | 2640篇 |
2013年 | 9328篇 |
2012年 | 2638篇 |
2011年 | 3211篇 |
2010年 | 3513篇 |
2009年 | 3667篇 |
2008年 | 2867篇 |
2007年 | 2812篇 |
2006年 | 2902篇 |
2005年 | 2806篇 |
2004年 | 3044篇 |
2003年 | 2926篇 |
2002年 | 2445篇 |
2001年 | 2937篇 |
2000年 | 2362篇 |
1999年 | 1676篇 |
1998年 | 1417篇 |
1997年 | 1410篇 |
1996年 | 1545篇 |
1995年 | 1630篇 |
1994年 | 1527篇 |
1993年 | 1372篇 |
1992年 | 1376篇 |
1991年 | 1342篇 |
1990年 | 1319篇 |
1989年 | 1247篇 |
1988年 | 1085篇 |
1987年 | 1019篇 |
1986年 | 1001篇 |
1985年 | 1083篇 |
1984年 | 1173篇 |
1983年 | 1180篇 |
1982年 | 1177篇 |
1981年 | 1106篇 |
1980年 | 959篇 |
1979年 | 945篇 |
1978年 | 830篇 |
1977年 | 720篇 |
1976年 | 647篇 |
1974年 | 634篇 |
1973年 | 652篇 |
1972年 | 664篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
541.
The Science of Nature - 相似文献
542.
Mitigation and Adaptation Strategies for Global Change - 相似文献
543.
The possible effects of landscape structure on starling roost distribution were investigated in western France using GIS analysis at different radii (2, 4, 8 and 10 km). Composition (11 land use classes) and configuration (patch size, diversity index) of the landscapes surrounding 97 roost sites used by starlings from 1981 to 2002 and surrounding 50 random points not used as roost sites were compared. Significant results suggested that starling roosts were established preferentially in the centre of an agricultural landscape where large units of pastures and arable land predominated and where natural areas were lacking both in large patches (forests or wetland classes) and in small patches such as woods in the mixed land class. A varied farmland landscape with natural areas and small patches should be promoted to limit the starling damage in wintering regions and also to favour their reproduction in regions where it has declined. 相似文献
544.
含纤维素废水生物水解的应用研究 总被引:1,自引:0,他引:1
提取植物或动物纤维所产生的高浓有机废水,含短小纤维、木质素、纤维素、半纤维素、蜡质、果胶及其分解产物(糖、脂肪酸、醇等),较难生物处理,属含纤维素废水。试验研究和生产应用表明,生物水解对含纤维素废水中高分子有机物,可予分解并提高度水可生化性:在常温、PH约9.5时,水解池污泥浓度达6.5~16.0g/L,容积负荷达2.9kgCOD/m^3.d,COD去除率为24—36%,VFA提高3.9—5.1倍,BOD/COD提高12~16%。分析认为:中温、酸性,纤维素、木素含量低时,水解效果应更好。 相似文献
545.
Jenny M. McCarthy Thomas Gumbricht Terence McCarthy Philip Frost Konrad Wessels Frank Seidel 《Ambio-人类环境杂志》2003,32(7):453-457
欧科范果三角洲地区泛滥范围年年在变化.这种变化与安哥拉高地集水区的区域性降水及当地降雨量有关.我们采用了1972~2000年的3000多幅卫星图像来描绘湿地的格局,其中从1985~2000年的图像几乎是NOAAAVHRR每日连续传送的,1972年以来的其它图像是从Landsat传感器上传下来的,其连续性次之.对AVHRR图像每10天为一期,用无监督分类方法分成陆地和水体.对LandsatTM和ERS2-ATSR数据进行分析的结果,与测算的淹没区域89%相吻合.结果显示欧科范果湿地近期30年期间的变化约在2450~11400km2之间. 相似文献
546.
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
547.
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
548.
549.
G. Siegert 《Die Naturwissenschaften》1984,71(7):370-371
550.