全文获取类型
收费全文 | 41628篇 |
免费 | 416篇 |
国内免费 | 309篇 |
专业分类
安全科学 | 1138篇 |
废物处理 | 1612篇 |
环保管理 | 5499篇 |
综合类 | 6808篇 |
基础理论 | 11429篇 |
环境理论 | 32篇 |
污染及防治 | 11014篇 |
评价与监测 | 2614篇 |
社会与环境 | 1937篇 |
灾害及防治 | 270篇 |
出版年
2022年 | 380篇 |
2021年 | 383篇 |
2020年 | 272篇 |
2019年 | 340篇 |
2018年 | 663篇 |
2017年 | 616篇 |
2016年 | 931篇 |
2015年 | 732篇 |
2014年 | 1078篇 |
2013年 | 3184篇 |
2012年 | 1341篇 |
2011年 | 1851篇 |
2010年 | 1474篇 |
2009年 | 1497篇 |
2008年 | 1850篇 |
2007年 | 1912篇 |
2006年 | 1660篇 |
2005年 | 1389篇 |
2004年 | 1320篇 |
2003年 | 1275篇 |
2002年 | 1236篇 |
2001年 | 1585篇 |
2000年 | 1109篇 |
1999年 | 715篇 |
1998年 | 518篇 |
1997年 | 550篇 |
1996年 | 557篇 |
1995年 | 638篇 |
1994年 | 573篇 |
1993年 | 514篇 |
1992年 | 514篇 |
1991年 | 495篇 |
1990年 | 487篇 |
1989年 | 513篇 |
1988年 | 435篇 |
1987年 | 382篇 |
1986年 | 363篇 |
1985年 | 376篇 |
1984年 | 372篇 |
1983年 | 403篇 |
1982年 | 406篇 |
1981年 | 353篇 |
1980年 | 314篇 |
1979年 | 355篇 |
1978年 | 284篇 |
1977年 | 249篇 |
1976年 | 243篇 |
1975年 | 251篇 |
1973年 | 216篇 |
1972年 | 239篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
J.M.R. Hutchinson 《Environment international》1980,3(5):363-364
The development of traceability in low-level radioactivity measurements is discussed. The role that the development of large quantities of natural matrix standards can play is also discussed. 相似文献
133.
Deposition velocities have been determined for corn and soybeans in the first 4–6 weeks of growth in a full-scale study of canopy flow in a wind tunnel. Particles of 1, 5, 10 and 15 μm aerodynamic diameter made of sodium florescein were injected into the Environmental Wind Tunnel Facility at Colorado State University. Deposition velocities were determined as a function of free stream velocity (183, 305 and 610 cm/s) and approach flow turbulence intensity (~1% and 8%). Plants were arranged in realistic field configurations. Hot-wire anemometer studies confirmed that the fluid velocity profiles developed in the wind tunnel were similar to the flow realized in canopies in natural fields. An increase in velocity and turbulence intensity was found to decrease the deposition velocities. A minimum deposition velocity was observed at a particle diameter of 5 μm. 相似文献
134.
135.
136.
137.
J A Heidman 《Journal - Water Pollution Control Federation》1975,47(6):1493-1498
138.
139.
140.
There is a growing recognition that knowledge of indigenous communities, based on accumulated observations and experience over time, is significant for sustainable environmental management in collaboration with modern scientific knowledge. A number of innovative policy initiatives are currently being implemented in New Zealand to enable indigenous Maori tribes and sub-tribes to rehabilitate and manage their local fisheries in accordance with customary values and practices. These policies are an important milestone from an historical perspective as they are meant to recognise and empower the role of Maori as Treaty partners. The fisheries management regime in New Zealand now provides for Maori representation at the local level within a co-management framework that enables local Maori communities to exercise their customary rights. These institutional arrangements have been crafted to facilitate Maori input, based on customary values and practices, to complement modern Western management practices for sustainable harvesting of marine resources. Nevertheless, the degree to which these initiatives constitute an adequate response to Maori Treaty aspirations is debatable. A major constraint in this respect is that the government is compelled to recognise the needs of other, economically and politically more dominant, non-Maori user-groups in allocating and managing access to fishery resources and the marine environment. 相似文献