全文获取类型
收费全文 | 35479篇 |
免费 | 424篇 |
国内免费 | 499篇 |
专业分类
安全科学 | 1130篇 |
废物处理 | 1685篇 |
环保管理 | 4243篇 |
综合类 | 6686篇 |
基础理论 | 8964篇 |
环境理论 | 26篇 |
污染及防治 | 9094篇 |
评价与监测 | 2398篇 |
社会与环境 | 1951篇 |
灾害及防治 | 225篇 |
出版年
2023年 | 168篇 |
2022年 | 384篇 |
2021年 | 373篇 |
2020年 | 280篇 |
2019年 | 331篇 |
2018年 | 582篇 |
2017年 | 567篇 |
2016年 | 856篇 |
2015年 | 674篇 |
2014年 | 998篇 |
2013年 | 2753篇 |
2012年 | 1225篇 |
2011年 | 1632篇 |
2010年 | 1343篇 |
2009年 | 1395篇 |
2008年 | 1637篇 |
2007年 | 1711篇 |
2006年 | 1449篇 |
2005年 | 1250篇 |
2004年 | 1122篇 |
2003年 | 1245篇 |
2002年 | 1071篇 |
2001年 | 1336篇 |
2000年 | 964篇 |
1999年 | 614篇 |
1998年 | 419篇 |
1997年 | 433篇 |
1996年 | 405篇 |
1995年 | 482篇 |
1994年 | 513篇 |
1993年 | 400篇 |
1992年 | 407篇 |
1991年 | 390篇 |
1990年 | 418篇 |
1989年 | 372篇 |
1988年 | 333篇 |
1987年 | 306篇 |
1986年 | 244篇 |
1985年 | 286篇 |
1984年 | 287篇 |
1983年 | 283篇 |
1982年 | 273篇 |
1981年 | 258篇 |
1980年 | 207篇 |
1979年 | 220篇 |
1978年 | 201篇 |
1977年 | 141篇 |
1975年 | 151篇 |
1972年 | 151篇 |
1971年 | 150篇 |
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
51.
Jürgen Heinze Bernhard Stengl Matthew F. Sledge 《Behavioral ecology and sociobiology》2002,52(1):59-65
Workers in de-queened colonies of the neotropical ant, Pachycondyla cf. inversa, form linear or near-linear dominance hierarchies by violent antennation and biting. In these rank orders, social status and ovarian activity are on average highly correlated. Whereas the presence of a fertile queen appears to be sufficient to prevent workers from laying eggs, fertile workers do not completely control reproduction by their nestmates, suggesting that workers are able to differentiate between an egg-laying queen and an egg-laying worker. Here we show that the composition of cuticular hydrocarbons of egg-laying workers is quantitatively and qualitatively different from that of non-laying workers and resembles the hydrocarbon blend of the queen but does not completely match it. Furthermore, using discriminant analysis, it was possible to distinguish workers with four different classes of ovarian development based only on their cuticular hydrocarbon profiles. Fertility-associated changes in cuticular hydrocarbons may play an important role in the behavioural regulation of reproduction in this ant. 相似文献
52.
53.
In the last 10 years, several studies have been carried out on the fish fauna of the Ustica Island marine reserve, yet no investigation was specifically addressed to the cryptobenthic fish assemblage. The first task of this study, conducted along the shallow rocky reefs of Ustica, was to determine the species composition, diversity and relative density of the resident cryptobenthic fishes. Furthermore, we aimed to assess the effects of some macro- and microscale habitat characteristics on the distribution pattern of fishes. In particular, the effect of predator density was indirectly evaluated by comparing density data collected within and outside the integral reserve zone. Overall, 20 species belonging to Blenniidae, Gobiidae, Tripterygiidae, Scorpaenidae and Gobiesocidae were recorded. Gobius bucchichi, Scorpaena maderensis, Tripterygion delaisi, T. melanurus and T. tripteronotus were the numerically dominant and most common species. The effects of zone (i.e. of predator density), bottom type and depth on species richness, diversity and evenness were not significant. A greater total fish density was observed on stones compared with rocky cliff and plateau, but only in the shallowest depth range. At level of single species, G. bucchichi was more abundant inside than outside the integral reserve, but only on stones and at 0–2 m depth range. Density of G. bucchichi was generally higher on stones than on rocky cliffs or plateau and between 0 and 5 m depth, although these differences were not always significant. T. delaisi was conversely more abundant in the deepest stratum (7–10 m). Canonical analyses demonstrated that bottom type and depth influenced significantly the fish assemblage structure. The observed differences in the assemblage structure relied mainly upon the dominant species. T. tripteronotus was mainly associated with rocky plateau and the intermediate depth range (3–5 m), whereas S. maderensis, T. melanurus and Lipophrys trigloides inhabited preferentially the rocky cliffs. At microscale level, the habitat choice of the investigated species was almost entirely based on whether the substrate was either vegetated or composed of bare rock. T. delaisi and T. tripteronotus were associated with substrata covered by algae, whilst G. bucchichi, S. maderensis and T. melanurus preferred bare rock bottoms. In some species, the electivity indices for the less abundant type of cover, measured at different spatial scale, changed accordingly. For instance, the smaller the size of the sampled area, the higher was the intensity of the association between G. bucchichi and Anemonia viridis. 相似文献
54.
Russian Journal of Ecology - 相似文献
55.
Effluent from dyeing and finishing processes is an important source of water pollution. The effectiveness of bentonite, kaolinite and sediment from a local deposit in removing methylene blue as a cationic dye from aqueous solutions has been investigated. The adsorption equilibrium (isotherm) has been determined according to Freundlich and Langmuir equations. The optimum amount is 0.5 g for all adsorbents, and the optimum pH ranges are 2-8 for bentonite and 2-6 for kaolinite and sediment. With respect to kinetic modelling, the adsorption of methylene blue on various adsorbents was fitted to a second-order equation. Also, the thermodynamic parameters were determined. The negative free energy values indicate the feasibility of the process and spontaneous nature of adsorption. The positive ΔH° values indicate the endothermic nature of the process. Thus, Egyptian clay minerals and sediments have a great tendency to remove the dye from solutions. 相似文献
56.
Although many conventional physical remediation methods are viewed as proven, they often only relocate wastes to other sites or into the air. How do the emerging biological and chemical in situ methods perform in the same applications? This article reviews their results (much of it in the laboratory) as well as their promise of more complete neutralization of hazardous wastes, lower capital costs, and longer-duration cleanup processes. The optimal method may be a combination of chemical and biological in situ techniques with physical pump-and-treat methods. 相似文献
57.
Nicola M. Marples 《Chemoecology》1993,4(1):29-32
Garden black ants,Lasius niger L., in a laboratory colony, attacked three species of live ladybirds found near their nest, killing the smaller two species. A second colony was offered artificial diets containing crushed ladybirds of two species, and the ants' choice of feeding site noted. Both the diets were aversive compared to control, but that containing 7spot,Coccinella septempunctata L., was more aversive than the diet containing 2spot,Adalia bipunctata L. The implications of this lesser protection for 2spots in terms of the chemical defence of the species are discussed. 相似文献
58.
59.
60.
Henrietta M. Lidiard Joy E. Rae Andrew Parker 《Environmental geochemistry and health》1993,15(2-3):93-104
A number of Mn-oxide minerals in soils from a farm in North Devon have been tentatively identified using a combination of
advanced analytical techniques: scanning electron microscopy (SEM), scanning electron microprobe (SEMP), X-ray diffraction
(XRD) and bulk chemical analysis by wet digestion followed by inductively-coupled plasma spectrometry (ICP). The minerals
lithiophorite and hollandite are thought to occur throughout the study area although there is considerable geographical variation
in the proportions of minerals present. Bimessite, vernadite, romanechite, todorokite and cryptomelane may also be present,
although in smaller amounts.
The use of SEMP, together with a simple sorption experiment, has allowed a study of the extent of uptake of Co and Cu by different
Mn-oxide minerals. Lithiophorite appears to take up Co and Cu more effectively than hollandite within a pH range of 4–6. 相似文献