全文获取类型
收费全文 | 241篇 |
免费 | 0篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 8篇 |
环保管理 | 25篇 |
综合类 | 83篇 |
基础理论 | 41篇 |
环境理论 | 2篇 |
污染及防治 | 61篇 |
评价与监测 | 7篇 |
社会与环境 | 4篇 |
灾害及防治 | 1篇 |
出版年
2021年 | 5篇 |
2020年 | 5篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 9篇 |
2005年 | 3篇 |
2004年 | 26篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1967年 | 4篇 |
1966年 | 5篇 |
1965年 | 4篇 |
1962年 | 2篇 |
1960年 | 4篇 |
1959年 | 3篇 |
1958年 | 2篇 |
1957年 | 8篇 |
1956年 | 2篇 |
1955年 | 1篇 |
1954年 | 3篇 |
1952年 | 2篇 |
1946年 | 2篇 |
1944年 | 1篇 |
1931年 | 1篇 |
1928年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 15 毫秒
51.
Here, we review Charles Darwin’s relation to beetles and developments in coleopteran systematics in the last two centuries.
Darwin was an enthusiastic beetle collector. He used beetles to illustrate different evolutionary phenomena in his major works,
and astonishingly, an entire sub-chapter is dedicated to beetles in “The Descent of Man”. During his voyage on the Beagle,
Darwin was impressed by the high diversity of beetles in the tropics, and he remarked that, to his surprise, the majority
of species were small and inconspicuous. However, despite his obvious interest in the group, he did not get involved in beetle
taxonomy, and his theoretical work had little immediate impact on beetle classification. The development of taxonomy and classification
in the late nineteenth and earlier twentieth century was mainly characterised by the exploration of new character systems
(e.g. larval features and wing venation). In the mid-twentieth century, Hennig’s new methodology to group lineages by derived
characters revolutionised systematics of Coleoptera and other organisms. As envisioned by Darwin and Ernst Haeckel, the new
Hennigian approach enabled systematists to establish classifications truly reflecting evolution. Roy A. Crowson and Howard
E. Hinton, who both made tremendous contributions to coleopterology, had an ambivalent attitude towards the Hennigian ideas.
The Mickoleit school combined detailed anatomical work with a classical Hennigian character evaluation, with stepwise tree
building, comparatively few characters and a priori polarity assessment without explicit use of the outgroup comparison method.
The rise of cladistic methods in the 1970s had a strong impact on beetle systematics. Cladistic computer programs facilitated
parsimony analyses of large data matrices, mostly morphological characters not requiring detailed anatomical investigations.
Molecular studies on beetle phylogeny started in the 1990s with modest taxon sampling and limited DNA data. This has changed
dramatically. With very large data sets and high throughput sampling, phylogenetic questions can be addressed without prior
knowledge of morphological characters. Nevertheless, molecular studies have not lead to the great breakthrough in beetle systematics—yet.
Especially the phylogeny of the extremely species rich suborder Polyphaga remains incompletely resolved. Coordinated efforts
of molecular workers and of morphologists using innovative techniques may lead to more profound insights in the near future.
The final aim is to develop a well-founded phylogeny, which truly reflects the evolution of this immensely species rich group
of organisms. 相似文献
52.
For phosphorus recovery from wastewater, the present paper aims at understanding the crystallization of calcium phosphate by using calcites (Juraperle and Coccolith) as seeds from hard water. Synthetic hard water with 60 mgCl(-1) carbonate and 10 mgPl(-1) phosphate was prepared and used in the batch experiments of calcite-seeded crystallization. The solution composition was measured throughout the batch crystallization process, and the corresponding saturation indices with respect to the minerals were calculated with PHREEQC Program. The surface of the calcite seeds was observed and measured with environmental scanning electron microscopy (ESEM), Fourier transform infrared (FTIR) and BET method. The studies show that both calcites are effective seeds for the crystallization of calcium phosphate from hard water; the used calcites are more efficient than the original ones because newly formed crystals with calcium phosphate have covered their surfaces. The studies show that the calcite seeds can be used for phosphorus recovery from hard waters. 相似文献
53.
René M. Rossi Walter Bolli Rolf Stämpfli 《International journal of occupational safety and ergonomics》2013,19(1):55-60
Heat and mechanical protection properties of 6 fabric combinations commonly used in firefighters’ protective clothing were assessed before and after different heat treatment. It was shown that after heat exposure, the values obtained were generally lower than in the original state. The mechanical properties of the materials were more affected by heat than by heat protective properties. In 2 cases, degradation started before a visible change in the material could be observed, which might be potentially dangerous for the end user who will not realize the alteration of the material. 相似文献
54.
对工业可燃粉尘爆炸基础研究进行了综述.对粉尘爆炸领域有史以来的主要基础研究成果进行了高度概括,内容涉及引起粉尘爆炸的可燃物质、影响粉尘云可燃性和爆炸性的因素、粉尘云在空气中的燃烧、引发粉尘爆炸的点火源、一次和二次粉尘爆炸、粉尘闪燃、杂混物的爆炸及粉尘云爆轰8个方面.回顾了粉尘爆炸的预防和缓解措施进展,指出了本质安全设计的意义.最后针对纳米颗粒粉尘的爆炸特性进行了探讨,通常粉尘的最小点火能随粉尘粒径减小而减小、爆炸指数随粉尘粒径减小而增大,这种趋势直到粉尘粒径减小到1~10 μm一直存在,但这种趋势可能不会持续到纳米粉体级别,可能的两个原因是纳米粉体的难于分散和凝并作用. 相似文献
55.
Douglas G. Sprugel Katherine G. Rascher Rolf Gersonde Martin Dovčiak James A. Lutz Charles B. Halpern 《Ecological modelling》2009
Young forests can be manipulated in diverse ways to enhance their ecological values. We used stem maps from two dense, second-growth stands in western Washington and a spatially explicit light model (tRAYci) to simulate effects of five silvicultural manipulations on diameter distribution, species composition, spatial patterning, and light availability. Each treatment removed 30% of the basal area, but differed in how trees were selected for removal. Three primary treatments were thin from below (removing the smallest trees), random thin (removing trees randomly), and gap creation (removing all trees in circles ∼1 tree height in diameter). Two additional treatments combined elements of these approaches: random ecological thin (a mixture of thin from below and random thin) and structured ecological thin (a mixture of thin from below and gap creation). 相似文献
56.
Nyberg Lars Lundström Ulla Söderberg Ulf Danielsson Rolf van Hees Patrick 《Water, Air, & Soil Pollution: Focus》2001,1(1-2):241-263
In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al., 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio. 相似文献
57.
Soil pollution in day-care centers and playgrounds in Norway: national action plan for mapping and remediation 总被引:1,自引:1,他引:0
Ottesen RT Alexander J Langedal M Haugland T Høygaard E 《Environmental geochemistry and health》2008,30(6):623-637
Systematic geochemical mapping based on sampling and analysis of surface soils (0–2 cm) has been carried out in several Norwegian
cities. The soils in the oldest parts of the cities are contaminated with metals (especially Pb) and polycyclic aromatic hydrocarbons
(PAH). Due to the fact that children are often in contact with surface soil, it was realized that special focus had to be
directed towards soils in day-care centers and playgrounds. The first mapping and remedy program was initiated in Trondheim
in 1996. Here, the importance of copper–chromium–arsenic (CCA)-pressure-impregnated wood in playing equipment as a pollution
source for soils was documented, and a process was started with the aim to ban this product. Soils from day-care centers in
the inner city of Bergen were polluted to a degree that required remediation in 45% out of 87 centers, mainly due to high
concentrations of Pb and benzo(a)pyrene. In Oslo, 38% of 700 day-care centers needed remediation due to soil pollution by
Pb, BaP, Cd, Hg, Ni and PCB. Removal of CCA-impregnated wood was necessary in more than half of the day-care centers The Norwegian
parliament has decided to investigate all outdoor playing areas in day-care centers, playgrounds and schoolyards in Norway,
starting in 2007 with day-care centers in the ten largest cities and five most important industrial areas. The Norwegian Institute
of Public Health has developed quality criteria for soils in day-care centers and playgrounds for As, Cd, Cr6+, Hg, Ni, Pb, zinc, PAHsum16, benzo(a)pyrene, and PCBsum7. The Geological Survey of Norway has developed guidance for mapping of soil pollution (sampling, chemical analysis and reporting)
in day-care centers. Especially the sampling strategy has been developed in the period 1996–2007, and the preferred sampling
strategy is to collect at least 10 samples of surface soil (0–2 cm) from (1) “original soil” on the site, (2) artificial man-made
“hills”, and (3) soils used for growing vegetables. A total number of 2,000 day-care-centres are to be investigated, and necessary
remediation should be completed before the end of 2010. 相似文献
58.
Terry V.Callaghan Lars Olof Bjrn Yuri Chernov Terry Chapin Torben R.Christensen Brian Huntley Rolf A.Ims Margareta Johansson Dyanna Jolly Sven Jonasson Nadya Matveyeva Nicolai Panikov Walter Oechel Gus Shaver Sibyll Schaphoff Stephen Sitch Christoph Zckler 《Ambio-人类环境杂志》2004,33(7):362-368
引言
北极已成为对当前气候波动和预计的全球变暖增强的影响进行评估的重要地区.原因有以下几个方面:①在过去几十年中北极经历了大幅度的变暖过程(温度平均升高3℃,而在许多地区温度升高了4~5℃);②气候预测表明气候呈现持续变暖趋势,在2080年之前年平均气温升高4~5℃;③近期的气候变暖正在影响北极的环境和经济,这些影响还会加大,并对生活方式、文化及生态系统造成影响;④北极的变化可能会影响到地球上的其它地区. 相似文献
59.
60.