全文获取类型
收费全文 | 310篇 |
免费 | 0篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 4篇 |
环保管理 | 27篇 |
综合类 | 220篇 |
基础理论 | 21篇 |
污染及防治 | 34篇 |
评价与监测 | 4篇 |
社会与环境 | 1篇 |
出版年
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1984年 | 5篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1968年 | 4篇 |
1964年 | 3篇 |
1963年 | 6篇 |
1961年 | 9篇 |
1960年 | 6篇 |
1959年 | 5篇 |
1958年 | 11篇 |
1957年 | 6篇 |
1955年 | 6篇 |
1954年 | 5篇 |
1953年 | 3篇 |
1947年 | 3篇 |
1943年 | 5篇 |
1941年 | 5篇 |
1939年 | 4篇 |
1938年 | 5篇 |
1937年 | 4篇 |
1935年 | 4篇 |
1934年 | 4篇 |
1933年 | 3篇 |
1932年 | 3篇 |
1929年 | 3篇 |
1928年 | 5篇 |
1926年 | 3篇 |
1925年 | 3篇 |
1923年 | 6篇 |
1921年 | 3篇 |
1920年 | 3篇 |
1919年 | 5篇 |
1916年 | 3篇 |
1915年 | 3篇 |
1914年 | 6篇 |
1913年 | 5篇 |
排序方式: 共有314条查询结果,搜索用时 15 毫秒
271.
272.
273.
274.
275.
Urs Baumann Caroline Brunner Ernst Pletscher Nicole Tobler 《Environmental Sciences Europe》2003,15(3):163-167
The goal of this work is to make ecotoxicologically-relevant substance bands visible on thin-layer chromatographic plates. Bacteria (Bacillus subtilis, Vibrio fischeri, Salmonella typhimurium), fungi (Aspergillus niger), algi (Pseudokirchneriella subcapitata) and pollen (Impatiens walleriana) were used as test organisms. With the aid of these organisms, it has been possible to identify bactericide, fungicide, algicide, phytotoxic and genotoxic bands. 相似文献
276.
277.
Ted L. Ernst Nancy C. Leibowitz Denis Roose Steve Stehman N. Scott Urquhart 《Environmental management》1995,19(1):99-113
The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) will monitor the
nation's resources by evaluating the status and trends of selected indicators of condition using a probability-based sampling
design. The EMAP-Wetlands program will monitor the condition of the nation's wetlands. The EMAP classification system is an
aggregation of the many subclasses of the US Fish and Wildlife Service's National Wetlands Inventory (NWI) classification
system. This aggregation results in fewer wetland classes with more wetlands per class than the NWI system. Aggregation of
the NWI classification was based primarily on dominant vegetation cover, flooding regimes, dominant water source, and adjacency
to rivers and lakes. We evaluated the EMAP classification system and sampling design using NWI digital wetlands data for portions
of Illinois, Washington, North Dakota, and South Dakata. Relative numbers of wetlands, total areas, average areas, and common
versus rare classes were compared between the EMAP and NWI classification systems. As expected, the EMAP classification provided
fewer wetland polygons, each with larger areas, without altering total wetland area. Summary statistics comparing sample estimates
to true population parameters (represented by the NWI data) demonstrated the effectiveness of the EMAP sampling design with
the exception of rare EMAP classes in the selected regions. Although simple random sampling is inadequate for both large and
small wetlands, the EMAP sampling design is readily adapted to provide better estimates for these categories. Aggregating
the NWI classification to the EMAP classification provides fewer wetland classes, with more wetlands per class, for EMAP's
annual reports and statistical summaries.
The research in this report has been funded by the United States Environmental Protection Agency (EPA) under contracts 68-C8-0006
to ManTech Environmental Technology, Inc. and 68-03-3532 to The Bionetics Corporation. Mention of trade names does not constitute
endorsement or recommendation for use. 相似文献
278.
Based on intergroup theory, this study examined relationships among group characteristics (racioethnicity, gender, and level), contextual organizational unit characteristics (gender and racioethnic heterogeneity, resource support for women and racioethnic minorities) and perceptions of diversity climate by faculty at a large university. Compared to white men, white women and racioethnic minorities placed greater value on employer efforts to promote diversity, and held more favorable attitudes about the qualifications of women and racioethnic minorities. The study found that group rather than contextual organizational unit characteristics were more strongly related to diversity climate. However, the organizational unit characteristic, gender heterogeneity, was significantly related to valuing diversity. The greater the ratio of women in a unit, regardless of the respondents' gender, racioethnicity or level, the more favorable diversity activities were viewed. In addition, units whose allocation of resources to racioethnic minorities were perceived as insufficient by respondents were more likely to have members who valued diversity and held favorable perceptions toward the qualifications of racioethnic minorities. Implications for organizations and future research are offered. 相似文献
279.
Ernst Auhagen 《Die Naturwissenschaften》1931,19(45):916-917
280.