全文获取类型
收费全文 | 251898篇 |
免费 | 16131篇 |
国内免费 | 35902篇 |
专业分类
安全科学 | 23575篇 |
废物处理 | 11617篇 |
环保管理 | 29048篇 |
综合类 | 102902篇 |
基础理论 | 47597篇 |
环境理论 | 211篇 |
污染及防治 | 50436篇 |
评价与监测 | 16583篇 |
社会与环境 | 14978篇 |
灾害及防治 | 6984篇 |
出版年
2024年 | 681篇 |
2023年 | 3283篇 |
2022年 | 9008篇 |
2021年 | 9040篇 |
2020年 | 8665篇 |
2019年 | 6791篇 |
2018年 | 7917篇 |
2017年 | 9247篇 |
2016年 | 9243篇 |
2015年 | 9152篇 |
2014年 | 11366篇 |
2013年 | 20921篇 |
2012年 | 16073篇 |
2011年 | 18043篇 |
2010年 | 15789篇 |
2009年 | 15567篇 |
2008年 | 15973篇 |
2007年 | 15667篇 |
2006年 | 14586篇 |
2005年 | 11275篇 |
2004年 | 8699篇 |
2003年 | 7669篇 |
2002年 | 6794篇 |
2001年 | 6180篇 |
2000年 | 5249篇 |
1999年 | 3590篇 |
1998年 | 2406篇 |
1997年 | 2186篇 |
1996年 | 2214篇 |
1995年 | 2290篇 |
1994年 | 2027篇 |
1993年 | 1490篇 |
1992年 | 1503篇 |
1991年 | 1362篇 |
1990年 | 1251篇 |
1989年 | 1145篇 |
1988年 | 1013篇 |
1987年 | 906篇 |
1986年 | 859篇 |
1985年 | 870篇 |
1984年 | 896篇 |
1983年 | 824篇 |
1982年 | 918篇 |
1981年 | 817篇 |
1980年 | 627篇 |
1979年 | 686篇 |
1978年 | 585篇 |
1977年 | 513篇 |
1975年 | 467篇 |
1974年 | 461篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
411.
Sergio Caroli Francesco La Torre Francesco Petrucci Nicola Violante 《Environmental science and pollution research international》1994,1(4):205-208
The separation and determination of sub-μmol/l levels of six environmentally significant As compounds was accomplished by
means of high performance liquid chromatography (HPLC) combined online with inductively coupled plasma mass spectrometry (ICP-MS).
The species of interest (arsenite and arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine)
were quantified in fish and mussel extracts after separation on a Dionex AS7 column equipped with an on-guard AG7 column using
a bicarbonate buffer as the mobile phase in a gradient mode. The species thus eluted were directly forwarded to the ICP-MS
detector. The detection power of the overall system allows each As form to be determined at concentrations as low a 0.0013–0.0027
μmol 1−1. 相似文献
412.
413.
414.
Critical loads offer a unique way of evaluating impacts of acid deposition by quantifying environmental sensitivity. The critical loads of acidity for UK peat soils have been based upon an arbitrary reduction in pH of 0.2 units. This chemical shift needs to be better related to adverse effects on sensitive biological receptors. It is known that effective precipitation pH equates closely to soil solution pH, and the latter is directly linkable to biotic effects of pH change. On continuation of a long-term experiment assessing impacts of simulated acid rain on peat microcosms in a realistic outdoor environment, Calluna vulgaris continued to flourish at acid deposition loads well above the existing critical load. Calluna plants were harvested and analysed, and acid deposition treatments to the microcosms continued to allow natural vegetation to regenerate. A diverse mixture of moorland plants and bryophytes established at acidity treatments well above the existing critical load, and only a very high acid load resulted in no natural regeneration. A critical effective rain pH value of 3.6 is suggested as a basis for setting critical loads. At this pH, Calluna grows well, and a healthy diverse vegetation community re-establishes when harvested. It is suggested that the peat critical load should be set at the acid load that, at any specific site, would result in a mean effective precipitation pH of 3.6. 相似文献
415.
Methodological Basis of Ecological Safety Standards for the Technogenic Impact of Mineral Resource Exploitation 总被引:1,自引:0,他引:1
A new methodological approach to the development of biological and technological safety standards for the impact of underground mining on the natural biota is proposed. 相似文献
416.
417.
Whereas past research has treated co-management of common pool resources as if villagers and project implementing authorities
were the only relevant actors, numerous external factors beyond the control of these two partners create barriers to successful
co-management. This paper draws on discussions with Forest Department officials to examine the influence of these forces on
the outcomes of Joint Forest Management (JFM) in Tamil Nadu, India. An empirical inquiry into the operational aspects of JFM
indicates the important roles of political parties, powerful people, and other state institutions and functionaries as well
as the flow of foreign funding. Further, the strong demand by local people for socio-economic development interventions as
opposed to improvement of degraded forests belittles the role of the Forest Department relative to other departments. Numerous
other conditioning factors and relationships are explored. The authors call for reforms in public governance to allow better
participation of all the actors involved for this participatory management approach to succeed and sustain. 相似文献
418.
选择位于红壤丘陵区的鄱阳湖流域作为研究对象,利用1 km×1 km分辨率的时序SPOT4 VEGETATION数据,对流域内典型土地覆被--常绿覆被的绿度值、峰值、谷值、年均NDVI(NDVI-I)和NDVI年内极差(NDVI MM)等特征值进行了提取。在此基础上,探讨了不同常绿覆被类型的NDVI指数年内季节变化规律。结果表明:时序NDVI指数基本上能够较好地刻画不同常绿覆被类型之间的差异性,植被指数NDVI特征值随覆被的类型及其生长状态有规律地变化,即NDVI年均值和最小值基本上按“常绿阔叶林>常绿针阔叶混交林>常绿针叶林>常绿针叶-落叶混交林”的顺序变化;典型常绿阔叶林的NDVI指数年内变化曲线基本上没有大的起伏波动;常绿针叶林以及常绿针阔叶混交林占主导地位的常绿混交林NDVI指数年内变化比较和缓,但常在8月和11月有所波动;以常绿针叶林为主、但有较多落〖JP2〗叶林混杂其中的常绿混交林,其NDVI指数年内变化曲线基本上呈和缓的单峰型波动。 相似文献
419.
N. P. Kosykh N. P. Mironycheva-Tokareva A. M. Peregon E. K. Parshina 《Russian Journal of Ecology》2008,39(7):466-474
New experimental data on biological productivity of plant communities in oligotrophic and mesotrophic bogs of the middle taiga
subzone over the past five years are presented. The relationship between net primary production and the stock of live phytomass
is estimated. The stock of necromass in oligotrophic bog ecosystems increases from west to east, while the stock of live phytomass
and net primary production decrease. 相似文献
420.