全文获取类型
收费全文 | 42963篇 |
免费 | 442篇 |
国内免费 | 548篇 |
专业分类
安全科学 | 1250篇 |
废物处理 | 1870篇 |
环保管理 | 5131篇 |
综合类 | 9316篇 |
基础理论 | 10506篇 |
环境理论 | 20篇 |
污染及防治 | 10799篇 |
评价与监测 | 2675篇 |
社会与环境 | 2153篇 |
灾害及防治 | 233篇 |
出版年
2022年 | 398篇 |
2021年 | 369篇 |
2020年 | 285篇 |
2019年 | 349篇 |
2018年 | 619篇 |
2017年 | 613篇 |
2016年 | 937篇 |
2015年 | 713篇 |
2014年 | 1085篇 |
2013年 | 3251篇 |
2012年 | 1308篇 |
2011年 | 1791篇 |
2010年 | 1497篇 |
2009年 | 1571篇 |
2008年 | 1821篇 |
2007年 | 1861篇 |
2006年 | 1605篇 |
2005年 | 1403篇 |
2004年 | 1334篇 |
2003年 | 1366篇 |
2002年 | 1264篇 |
2001年 | 1633篇 |
2000年 | 1135篇 |
1999年 | 710篇 |
1998年 | 495篇 |
1997年 | 500篇 |
1996年 | 493篇 |
1995年 | 597篇 |
1994年 | 604篇 |
1993年 | 504篇 |
1992年 | 527篇 |
1991年 | 515篇 |
1990年 | 564篇 |
1989年 | 513篇 |
1988年 | 421篇 |
1987年 | 403篇 |
1986年 | 365篇 |
1985年 | 388篇 |
1984年 | 416篇 |
1983年 | 406篇 |
1982年 | 393篇 |
1981年 | 388篇 |
1980年 | 309篇 |
1979年 | 336篇 |
1978年 | 289篇 |
1977年 | 235篇 |
1974年 | 239篇 |
1972年 | 248篇 |
1971年 | 241篇 |
1967年 | 259篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
D Heinevetter H J Lewerenz R Plass R Macholz 《Journal of environmental science and health. Part. B》1985,20(5):539-558
In vitro investigations of the influence of lindane and its metabolites were performed on microsomal and mitochondrial ATPases from liver, kidney and brain of rat and mouse. The microsomal Na+-K+-ATPases in rat liver were inhibited by the tested substances. An increase of activity was observed only with 2.5 X 10(-5) M gamma-HCH. Effects on the microsomal Na+-K+-ATPase from kidney and brain of rat were also indicated. The mitochondrial enzyme in rat liver was stimulated by all the compounds tested at concentrations of 10(-4) M - 10(-2) M. The effects on mitochondrial enzymes from kidney and brain varied in dependence on the tested substances. In the microsomes and mitochondria of mouse an influence on the Na+-K+-ATPases similar to the effects on the preparations from organs of rat was evident. 相似文献
32.
33.
34.
V. Nataf M. V. Senat M. Albert L. Bidat P. de Mazancourt J. Roume L. Allard D. Le Tessier Y. Ville J. Selva 《黑龙江环境通报》2002,22(8):675-680
Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
35.
36.
P Joseph S Viswanatha M K Krishnakumari 《Journal of environmental science and health. Part. B》1992,27(3):269-280
The haematotoxicity of technical hexachlorocyclohexane (HCH) (1000 ppm) was investigated in male albino rats fed with diet free of vitamin A or containing vitamin A at 2000 or 10(5) I.U./kg. Assessment of HCH-induced haematotoxicity at the end of the 7 weeks feeding period was done on the basis of haemoglobin content, total count of red blood cells and white blood cells and the differential counts of the white blood cells as well as by parameters such as packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin content, prothrombin time and clotting time. In the rats fed with vitamin A-free diet containing HCH, significant reductions were noticed in the total white blood cells count, clotting time and prothrombin time indicating severe haematotoxicity. Differential count of the white blood cells of these rats revealed a non-significant reduction in the lymphocyte count. The only indication of haematotoxicity caused by hexachlorocyclohexane in the vitamin A supplemented rats was a slight but statistically significant reduction of the total count of white blood cells. These results demonstrate that the haematotoxicity of hexachlorocyclohexane in the rats is enhanced by vitamin A-deficiency and its supplementation particularly in excess but not at hypervitaminotic level is protective against the toxicity. 相似文献
37.
From 1988 to 1991, we studied the postfledging dispersal of 31 radio-tagged White-crowned Pigeons ( Columba leucocephala ) from three natal keys in Florida Bay. Immature birds dispersed from the natal keys at 26–45 days after batching, and most young dispersed more than 20 km during the first 10 days postdispersal. Dispersing birds flew either north to the Florida mainland or east to northeast to the mainline Florida Keys. On the mainland, immature birds fed nearly exclusively within Everglades National Park or an adjacent state wildlife management area. On the mainline keys, White-crowned Pigeons selectively used 5.01–20 ha forest fragments (p < 0.10) during the first 72 hours postdispersal. After this period, dispersing birds showed no preference among fragment size classes but used deciduous seasonal forests more frequently than suburban habitat(p < 0.10). The spatial pattern of dispersal on the mainline keys suggests that, during the first 72 hours postdispersal. White-crowned Pigeons are not able to reach northern Key Largo, where 69% of the deciduous seasonal forests are protected in state or federal ownership. Protection of large forest fragments, especially on southern Key Largo, should be a priority for maintaining populations of White-crowned Pigeons. These forests provide a series of "stepping stones" that enable dispersing immature White-crowned Pigeons to fly to more distant areas where habitat availability is less restricted. This species is threatened in Florida and may play an important role in maintaining plant species diversity in the seasonal deciduous forests of south Florida by dispersing seeds of at least 37 species of trees and shrubs. Protection of sufficient habitat to allow successful postfledging dispersal of this important seed disperser will also protect the ecosystem's biodiversity. 相似文献
38.
An experimental investigation of explanations for inconsistencies in responses to second offers in double referenda 总被引:1,自引:0,他引:1
Anthony C. Burton Katherine S. Carson Susan M. Chilton W. George Hutchinson 《Journal of Environmental Economics and Management》2003,46(3):472
This paper demonstrates the potential for induced preference experiments to test previously unverified explanations of observed behavior in contingent valuation surveys. The NOAA Panel on Contingent Valuation called for experimental evidence on potential biases in the double referendum format. We test Carson, Groves, and Machina's (Incentives and informational properties of preference questions, Plenary address to the European Association of Resource and Environmental Economists, Oslo, Norway, June 1999) simple cost uncertainty and weighted averaging explanations of inconsistent responses to follow-up offers in such double referenda against a baseline of certainty and truthful preference revelation. The results find evidence to support the Weighted Average hypothesis. Results regarding the cost uncertainty hypothesis are more ambiguous and merit further investigation. 相似文献
39.
ABSTRACT: Two dynamic programming models — one deterministic and one stochastic — that may be used to generate reservoir operating rules are compared. The deterministic model (DPR) consists of an algorithm that cycles through three components: a dynamic program, a regression analysis, and a simulation. In this model, the correlation between the general operating rules, defined by the regression analysis and evaluated in the simulation, and the optimal deterministic operation defined by the dynamic program is increased through an iterative process. The stochastic dynamic program (SDP) describes streamflows with a discrete lag-one Markov process. To test the usefulness of both models in generating reservoir operating rules, real-time reservoir operation simulation models are constructed for three hydrologically different sites. The rules generated by DPR and SDP are then applied in the operation simulation model and their performance is evaluated. For the test cases, the DPR generated rules are more effective in the operation of medium to very large reservoirs and the SDP generated rules are more effective for the operation of small reservoirs. 相似文献
40.
A significant positive correlation between the lipid content of eight fish species and their bioconcentration factor (BCF) of 1,2,4-trichlorobenzene is demonstrated. The log BCF value on a lipid basis is in good agreement with the log n-octanol/water partition coefficient. 相似文献