全文获取类型
收费全文 | 34220篇 |
免费 | 416篇 |
国内免费 | 516篇 |
专业分类
安全科学 | 1129篇 |
废物处理 | 1639篇 |
环保管理 | 4772篇 |
综合类 | 5371篇 |
基础理论 | 8820篇 |
环境理论 | 23篇 |
污染及防治 | 8930篇 |
评价与监测 | 2317篇 |
社会与环境 | 1924篇 |
灾害及防治 | 227篇 |
出版年
2023年 | 152篇 |
2022年 | 332篇 |
2021年 | 351篇 |
2020年 | 266篇 |
2019年 | 337篇 |
2018年 | 531篇 |
2017年 | 554篇 |
2016年 | 828篇 |
2015年 | 654篇 |
2014年 | 968篇 |
2013年 | 2870篇 |
2012年 | 1198篇 |
2011年 | 1618篇 |
2010年 | 1325篇 |
2009年 | 1353篇 |
2008年 | 1638篇 |
2007年 | 1698篇 |
2006年 | 1451篇 |
2005年 | 1231篇 |
2004年 | 1130篇 |
2003年 | 1216篇 |
2002年 | 1091篇 |
2001年 | 1298篇 |
2000年 | 953篇 |
1999年 | 605篇 |
1998年 | 407篇 |
1997年 | 413篇 |
1996年 | 419篇 |
1995年 | 481篇 |
1994年 | 497篇 |
1993年 | 405篇 |
1992年 | 440篇 |
1991年 | 392篇 |
1990年 | 427篇 |
1989年 | 376篇 |
1988年 | 321篇 |
1987年 | 307篇 |
1986年 | 259篇 |
1985年 | 284篇 |
1984年 | 306篇 |
1983年 | 301篇 |
1982年 | 275篇 |
1981年 | 268篇 |
1980年 | 212篇 |
1979年 | 212篇 |
1978年 | 195篇 |
1977年 | 132篇 |
1975年 | 151篇 |
1972年 | 135篇 |
1971年 | 143篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
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
42.
43.
Data on the existence of a specific system regulating the growth, size, and structure of enterobacterial populations are first summarized in terms of the chemical ecology concept formulated by S.S. Shvarts. The role of this system in transgene functioning is described using the example of the lux operon integrated into Escherichia coli. A relatively simple test for estimating such interactions is proposed.Translated from Ekologiya, No. 2, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Pshenichnov, Maslennikova, Nikitina. 相似文献
44.
Alan R. Thornhill John A. McGrath Robin A. J. Eady Peter R. Braude Alan H. Handyside 《黑龙江环境通报》2001,21(6):490-497
Single cell polymerase chain reaction (PCR) for preimplantation genetic diagnosis (PGD) requires high efficiency and accuracy. Allele dropout (ADO), the random amplification failure of one of the two parental alleles, remains the most significant problem in PCR-based PGD testing since it can result in serious misdiagnosis for compound heterozygous or autosomal dominant conditions. A number of different strategies (including the use of lysis buffers to break down the cell and make the DNA accessible) have been employed to combat ADO with varying degrees of success, yet there is still no consensus among PGD centres over which lysis buffer should be used (ESHRE PGD Consortium, 1999 ). To address this issue, PCR amplification of three genes (CFTR, LAMA3 and PKP1) at different chromosomal loci was investigated. Single lymphocytes from individuals heterozygous for mutations within each of the three genes were collected and lysed in either alkaline lysis buffer (ALB) or proteinase K/SDS lysis buffer (PK). PCR amplification efficiencies were comparable between alkaline lysis and proteinase K lysis for PCR products spanning each of the three mutated loci (ΔF508 in CFTR 90% vs 88%; R650X in LAMA3 82% vs 78%; and Y71X in PKP1 91% vs 87%). While there was no appreciable difference between ADO rates between the two lysis buffers for the LAMA3 PCR product (25% vs 26%), there were significant differences in ADO rates between ALB and PK for the CFTR PCR product (0% vs 23%) and the PKP1 PCR product (8% vs 56%). Based on these results, we are currently using ALB in preference to PK/SDS buffer for the lysis of cells in clinical PGD. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
45.
46.
Brent M. Matsuda 《Conservation biology》1997,11(6):1449-1450
47.
48.
M Mora R Skiles B McKinney M Paredes D Buckler D Papoulias D Klein 《Environmental pollution (Barking, Essex : 1987)》2002,116(1):169-176
Peregrine falcons (Falco peregrinus) have been recorded nesting in Big Bend National Park, Texas, USA and other areas of the Chihuahuan Desert since the early 1900s. From 1993 to 1996, peregrine falcon productivity rates were very low and coincided with periods of low rainfall. However, low productivity also was suspected to be caused by environmental contaminants. To evaluate potential impacts of contaminants on peregrine falcon populations, likely avian and bat prey species were collected during 1994 and 1997 breeding seasons in selected regions of western Texas, primarily in Big Bend National Park. Tissues of three peregrine falcons found injured or dead and feathers of one live fledgling also were analyzed. Overall, mean concentrations of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], a metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], were low in all prey species except for northern rough-winged swallows (Stelgidopteryx serripennis, mean = 5.1 microg/g ww). Concentrations of mercury and selenium were elevated in some species, up to 2.5 microg/g dw, and 15 microg/g dw, respectively, which upon consumption could seriously affect reproduction of top predators. DDE levels near 5 microg/g ww were detected in carcass of one peregrine falcon found dead but the cause of death was unknown. Mercury, selenium, and DDE to some extent, may be contributing to low reproductive rates of peregrine falcons in the Big Bend region. 相似文献
49.
50.