全文获取类型
收费全文 | 3508篇 |
免费 | 11篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 80篇 |
废物处理 | 162篇 |
环保管理 | 380篇 |
综合类 | 482篇 |
基础理论 | 1232篇 |
环境理论 | 2篇 |
污染及防治 | 756篇 |
评价与监测 | 230篇 |
社会与环境 | 225篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 20篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 136篇 |
2017年 | 136篇 |
2016年 | 201篇 |
2015年 | 77篇 |
2014年 | 42篇 |
2013年 | 72篇 |
2012年 | 447篇 |
2011年 | 246篇 |
2010年 | 68篇 |
2009年 | 74篇 |
2008年 | 78篇 |
2007年 | 103篇 |
2006年 | 97篇 |
2005年 | 414篇 |
2004年 | 550篇 |
2003年 | 419篇 |
2002年 | 73篇 |
2001年 | 50篇 |
2000年 | 35篇 |
1999年 | 47篇 |
1998年 | 10篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 18篇 |
1994年 | 14篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1984年 | 2篇 |
1980年 | 8篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1966年 | 4篇 |
1961年 | 2篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1937年 | 1篇 |
1920年 | 1篇 |
排序方式: 共有3555条查询结果,搜索用时 15 毫秒
1.
2.
3.
Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder. 相似文献
4.
The modern theory of biological evolution: an expanded synthesis 总被引:12,自引:2,他引:12
In 1858, two naturalists, Charles Darwin and Alfred Russel Wallace, independently proposed natural selection as the basic mechanism responsible for the origin of new phenotypic variants and, ultimately, new species. A large body of evidence for this hypothesis was published in Darwins Origin of Species one year later, the appearance of which provoked other leading scientists like August Weismann to adopt and amplify Darwins perspective. Weismanns neo-Darwinian theory of evolution was further elaborated, most notably in a series of books by Theodosius Dobzhansky, Ernst Mayr, Julian Huxley and others. In this article we first summarize the history of life on Earth and provide recent evidence demonstrating that Darwins dilemma (the apparent missing Precambrian record of life) has been resolved. Next, the historical development and structure of the modern synthesis is described within the context of the following topics: paleobiology and rates of evolution, mass extinctions and species selection, macroevolution and punctuated equilibrium, sexual reproduction and recombination, sexual selection and altruism, endosymbiosis and eukaryotic cell evolution, evolutionary developmental biology, phenotypic plasticity, epigenetic inheritance and molecular evolution, experimental bacterial evolution, and computer simulations (in silico evolution of digital organisms). In addition, we discuss the expansion of the modern synthesis, embracing all branches of scientific disciplines. It is concluded that the basic tenets of the synthetic theory have survived, but in modified form. These sub-theories require continued elaboration, particularly in light of molecular biology, to answer open-ended questions concerning the mechanisms of evolution in all five kingdoms of life.Dedicated to Prof. Dr. Dr. hc mult. Ernst Mayr on the occasion of his 100th birthdayThis revised version was published online in March 2004, with corrections to the caption of Figure 6. 相似文献
5.
6.
Michael H?der 《Die Naturwissenschaften》1989,76(7):340
Naturwissenschaften Aktuell
Großforschung mit anderen Namen 相似文献7.
8.
9.
Christopher R. Ellis Jerry Champlin Heinz G. Stefan 《Journal of the American Water Resources Association》1997,33(6):1363-1374
ABSTRACT: Evidence is presented that snowmelt runoff from an urban watershed can produce density current intrusions (underflows) in a lake. Several episodes of density current intrusions are documented. Water temperatures and salinities measured near the bottom of a 10 m deep Minneapolis lake during the late winter warming periods in 1989, 1990, 1991, and 1995 show significant rapid changes which are correlated with observed higher air temperatures and snowmelt runoff. The snowmelt runoff entering this particular lake (Ryan Lake) has increased electrical conductivity, salinity, and density. The source of the salinity is the salt spread on urban streets in the winter. Heating of littoral waters in spring may also contribute to the occurrence of the sinking flows, but is clearly not the only cause. 相似文献
10.
Public Perception of Flood Hazard in the Niger Delta,Nigeria 总被引:3,自引:0,他引:3
Summary Our study had the aim of understanding how floodplain dwellers regard the risk of flooding. About 500 questionnaires were
administered to landowners in the selected settlements in the study area using systematic random sampling. The results of
analysis show, among other things, that the population regards most important the causes of floods as heavy, prolonged rainfall
and river overflow. Nevertheless, they have little knowledge of the frequency of severe floods, and flood alleviation schemes.
Most flood victims do not get compensation or relief during flood disaster, and the reason why they remain in the study area
is influenced by their occupations, especially fishing, subsistence agriculture, and the presence of crude oil in the region
which has attracted many migrants who cannot afford the high cost of accommodation and are therefore forced to live in vulnerable
areas of the floodplain. Finally, the study concludes that flood control in the region needs the cooperation of government,
community efforts and an enlightenment programmes through environmental education and mass media. 相似文献