全文获取类型
收费全文 | 436篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 12篇 |
废物处理 | 13篇 |
环保管理 | 37篇 |
综合类 | 158篇 |
基础理论 | 100篇 |
污染及防治 | 98篇 |
评价与监测 | 15篇 |
社会与环境 | 11篇 |
出版年
2021年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 21篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 19篇 |
2008年 | 14篇 |
2007年 | 18篇 |
2006年 | 24篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 16篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1966年 | 7篇 |
1965年 | 3篇 |
1964年 | 5篇 |
1963年 | 4篇 |
1962年 | 5篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1955年 | 4篇 |
1954年 | 3篇 |
1952年 | 2篇 |
1951年 | 3篇 |
1943年 | 2篇 |
1940年 | 2篇 |
1939年 | 2篇 |
1923年 | 2篇 |
排序方式: 共有444条查询结果,搜索用时 0 毫秒
441.
H. Borchert H. Seilkopf H. Musso G. Schramm Hans Ulrich 《Die Naturwissenschaften》1955,42(11):351-352
442.
Driver-training and emergency brake performance in cars with antilock braking systems 总被引:1,自引:0,他引:1
The purpose of this study was to assess the effects of a two-day post-license driver-training program on brake performance in cars with antilock braking systems (ABS). A trainee group (n = 26) and a control group (n = 13) participated in the experiment. The trainee group were enrolled in a two-day training course that included instruction in a braking technique that may be used in cars with and without ABS. All participants performed emergency brake tests from 80 and 100 km h−1 in an instrumented car before and after the training period. Results indicated the post-training group used a smoother braking profile, were less reliant on ABS activation, had enhanced postural stability, but took about one car length longer to stop from 100 km h−1 compared with the control group. Implications of these results for braking in cars with and without ABS, and for driver education programs in general are discussed. 相似文献
443.
R. A. Phillips M. K. Petersen K. Lilliendahl J. Solmundsson K. C. Hamer C. J. Camphuysen B. Zonfrillo 《Marine Biology》1999,135(1):159-170
The massive expansion in breeding numbers and range of the northern fulmar Fulmarus glacialis over the last two centuries is generally attributed to an increased availability of fish offal and discarded fishes from
commercial fisheries. This implies that discards should be a major component in fulmar diets in the more recently colonised
areas in the south of their range. This paper examines the contemporary diet of the northern fulmar at three major breeding
sites, Fair Isle (Shetland, UK), Iceland and Disko Fjord (western Greenland). At Fair Isle, 89% of regurgitates contained
fishes, with sandeels (Ammodytidae) recorded in 37%; 32% contained crustaceans (mainly decapods); 8% contained squid. There
was also a temporal trend; sandeels declining and crustaceans increasing in the diet from July to August. In Iceland, fishes
were also the main prey (47 to 93% of wet mass), with sandeels common in the south and west, and capelin (Mallotus villosus) in the north and east. Other fish species were mainly discards, and together with discarded decapods and fish offal formed
5 to 72% of the diet, depending on the sector. Euphausiids, amphipods and copepods constituted 3 to 13% of the diet. At Disko,
39% of samples contained fishes, 64% contained crustaceans (mainly amphipods), 22% contained squid, and 16% contained pteropods.
There was a clear temporal trend, with the bulk of the samples made up of crustaceans in mid-June, capelin from late June
to late July, and crustaceans and pteropods from late July to late August. An extensive review of published studies was also
carried out. The general pattern was for birds in more southerly populations to consume more discarded fishes, fish offal
and benthic invertebrates. However, a considerable proportion of their diet also consisted of juvenile gadids, sandeels, capelin
and pelagic zooplankton, which fulmars catch for themselves, and we suggest that breeding adults in the south are less dependent
on fishing waste than is generally assumed.
Received: 25 September 1998 / Accepted: 7 May 1999 相似文献
444.
The German biologist August Weismann (1834–1914) proposed that amphimixis (sexual reproduction) creates variability for natural selection to act upon, and hence he became one of the founders of the Neo-Darwinian theory of biological evolution. He is perhaps best known for what is called “Weismann’s Doctrine” or “Weismann’s Barrier” (i.e. the irreversible separation of somatic and germ cell functionalities early during ontogeny in multicellular organisms). This concept provided an unassailable argument against “soft inheritance” sensu Lamarck and informed subsequent theorists that the only “individual” in the context of evolution is the mature, reproductive organism. Herein, we review representative model organisms whose embryology conforms to Weismann’s Doctrine (e.g. flies and mammals) and those that do not (e.g. freshwater hydroids and plants) based on this survey and the Five Kingdoms of Life scheme; we point out that most species (notably bacteria, fungi, protists and plants) are “non-Weismannian” in ways that make a canonical definition of the “individual” problematic if not impossible. We also review critical life history functional traits that allow us to create a matrix of all theoretically conceivable life cycles (for eukaryotic algae, embryophytes, fungi and animals), which permits us to establish where this scheme Weismann’s Doctrine holds true and where it does not. In addition, we argue that bacteria, the dominant organisms of the biosphere, exist in super-cellular biofilms but rarely as single (planktonic) microbes. Our analysis attempts to show that competition among genomic variants in cell lineages played a critical part in the evolution of multicellularity and life cycle diversity. This feature was largely ignored during the formulation of the synthetic theory of biological evolution and its subsequent elaborations. 相似文献