全文获取类型
收费全文 | 4224篇 |
免费 | 74篇 |
国内免费 | 39篇 |
专业分类
安全科学 | 229篇 |
废物处理 | 143篇 |
环保管理 | 1103篇 |
综合类 | 401篇 |
基础理论 | 1029篇 |
环境理论 | 7篇 |
污染及防治 | 936篇 |
评价与监测 | 273篇 |
社会与环境 | 181篇 |
灾害及防治 | 35篇 |
出版年
2023年 | 14篇 |
2022年 | 29篇 |
2021年 | 40篇 |
2020年 | 37篇 |
2019年 | 45篇 |
2018年 | 62篇 |
2017年 | 81篇 |
2016年 | 101篇 |
2015年 | 91篇 |
2014年 | 90篇 |
2013年 | 522篇 |
2012年 | 161篇 |
2011年 | 214篇 |
2010年 | 140篇 |
2009年 | 153篇 |
2008年 | 193篇 |
2007年 | 238篇 |
2006年 | 171篇 |
2005年 | 133篇 |
2004年 | 143篇 |
2003年 | 163篇 |
2002年 | 132篇 |
2001年 | 72篇 |
2000年 | 90篇 |
1999年 | 54篇 |
1998年 | 66篇 |
1997年 | 53篇 |
1996年 | 69篇 |
1995年 | 62篇 |
1994年 | 81篇 |
1993年 | 62篇 |
1992年 | 50篇 |
1991年 | 44篇 |
1990年 | 47篇 |
1989年 | 35篇 |
1988年 | 45篇 |
1987年 | 30篇 |
1986年 | 40篇 |
1985年 | 42篇 |
1984年 | 36篇 |
1983年 | 49篇 |
1982年 | 58篇 |
1981年 | 53篇 |
1980年 | 32篇 |
1979年 | 34篇 |
1978年 | 29篇 |
1977年 | 31篇 |
1976年 | 14篇 |
1974年 | 12篇 |
1972年 | 12篇 |
排序方式: 共有4337条查询结果,搜索用时 15 毫秒
991.
Dr Joyce C. Harper Edith Coonen Alan H. Handyside Robert M. L. Winston Anton H. N. Hopman Joy D. A. Delhanty 《黑龙江环境通报》1995,15(1):41-49
We have previously detected chromosome abnormalities in human embryos whilst identifying the sex for preimplantation diagnosis of X-linked disease. In this study we assess the incidence of these abnormalities, both for sex chromosomes and autosomes 1 and 17, using dual fluorescent in situ hybridization (FISH). Sixty-nine normally fertilized embryos of good morphology at the 6–10 cell stage (day 3 post-insemination) were examined. The embryos were spread whole using HCl and Tween 20 to dissolve the cytoplasm. Thirty-four embryos were analysed for the sex chromosomes and 35 for autosomes 1 and 17. All probes were directly labelled with fluorochromes allowing analysis in 2 h. Control lymphocytes demonstrated that the probes were of high specificity. For the sex chromosomes, five embryos were mosaic (15 per cent) with the remaining 29 being uniformly XX or XY. In no case was an XX nucleus found in an otherwise XY embryo, indicating that even though mosaicism for the sex chromosomes is present, such abnormalities would not lead to a misdiagnosis of sex. For the autosomes, 16 embryos were abnormal (46 per cent); one embryo was triploid, one was monosomic for chromosome 1, and ten others were diploid mosaics (three diploid/aneuploid, three diploid/polyploid, and four diploid/haploid). A further four embryos had variable chromosome numbers in the majority of nuclei which appeared to be the result of uncontrolled mitotic division. The presence of haploidy or double monosomy, which occurred in 15 per cent of nuclei, has important implications for the diagnosis of trisomies and dominant disorders. 相似文献
992.
An evaluation of all fetuses from our institution with prenatally diagnosed cephaloceles was conducted to determine the frequency and spectrum of genetic syndromes associated with this abnormality. Review of the sonographic images, postnatal autopsy or pathology reports, delivery room records, paediatric neurosurgical findings, radiographs, and cytogenetic data were collected. Fifteen postnatally confirmed cases of prenatally diagnosed cephaloceles and two misdiagnosed cases were identified. Thirteen were midline occipital lesions, one was frontoparietal, and one was frontoethmoidal. Excluding microcephaly, hydrocephaly, and distortion of intracranial anatomy, 9 of 15 (60 per cent) had other associated anomalies, including two fetuses with aneuploidy. The prenatal diagnosis of a cephalocele should initiate a thorough search for other abnormalities. In this series, there were three multifactorial, two chromosomal, two sporadic, and two autosomal recessive syndromes identified. An accurate diagnosis is critical in determining the prognosis and providing appropriate genetic counselling. 相似文献
993.
Life on the Edge: Vulnerability and Adaptation of African Ecosystems to Global Climate Change 总被引:1,自引:1,他引:1
Dixon Robert K. Smith Joel Guill Sandra 《Mitigation and Adaptation Strategies for Global Change》2003,8(2):93-113
Donor countriesare providing financial and technicalsupport for global climate change countrystudies to help African nations meet theirreporting needs under the United NationsFramework Convention on Climate Change(UNFCCC). Technical assistance to completevulnerability and adaptation assessmentsincludes training of analysts, sharing ofcontemporary tools (e.g. simulationmodels), data and assessment techniques,information-sharing workshops and aninternational exchange programme foranalysts. This chapter summarizes 14African country studies (Botswana, Côted'Ivoire, Egypt, Ethiopia, the Gambia,Kenya, Malawi, Mauritius, Nigeria, SouthAfrica, Tanzania, Uganda, Zambia andZimbabwe) assessing vulnerabilities toglobal climate change and identifyingadaptation options. The analysis revealedthat the participating African countriesare vulnerable to global climate change inmore than one of the followingsocio-economic sectors: coastal resources,agriculture, grasslands and livestock,water resources, forests, wildlife, andhuman health. This vulnerability isexacerbated by widespread poverty,recurrent droughts, inequitable landdistribution, environmental degradation,natural resource mismanagement anddependence on rain-fed agriculture. Arange of practical adaptation options wereidentified in key socio-economic sectors ofthe African nations analysed. However,underdeveloped human and institutionalcapacity, as well as the absence ofadequate infrastructure, renders manytraditional coping strategies (rooted inpolitical and economic stability)ineffective or insufficient. FutureAfrican country studies should be moreclosely coordinated with development ofnational climate change action plans 相似文献
994.
James D. Goldberg MD Frank A. Chervenak Robert A. Lipman Richard L. Berkowitz 《黑龙江环境通报》1986,6(1):45-49
Arthrogryposis Multiplex Congenita (AMC) was suspected on ultrasound examination of a fetus at 30·5 weeks of gestation. The criteria for establishing this prenatal diagnosis as well as the importance of establishing the diagnosis at any gestational age are discussed. The diagnosis of AMC was confirmed at birth in this case. 相似文献
995.
Vespine wasps have been shown to deposit an attractive chemical in the nest entrance. Foragers use this to help locate the nest when returning to it. We determined how many individuals need to track (pass through) the entrance before the chemical is recognized. We found a logistic response as the number of tracks increased. At 200 tracks and above there was a 75–90% positive response rate to the chemical. We found no evidence of trail-marking behavior performed by foragers inside the nest entrance. We conclude that the trail is not an evolved signal, but is a cue composed of an accumulation of hydrocarbons deposited from the legs or feet of workers as they walk on a substrate. This is the first quantitative measurement of the attractiveness of the nest-entrance chemical in a social wasp. 相似文献
996.
Animals assess the fighting ability of conspecifics either by engaging in aggressive interactions or observing contests between others. However, whether individuals assess physical prowess outside the context of aggressive interactions remains unknown. We examined whether male green swordtails (Xiphophorus helleri) extract information about the fighting ability of solitary individuals via observation and whether acquiring such information elicits behavioral modifications. Contests preceded by mutual visual assessment were significantly shorter than fights where only one or neither of the two individuals was informed in advance. Focal animals initiated aggressive behavior more often against larger opponents only after previewing their adversary, indicating that swordtails can extract information about relative body size from watching solitary conspecifics. When a fighting disadvantage is perceived, observers adopt tactics that increase their probability of winning the contest. 相似文献
997.
环境危机管理经验研究 总被引:1,自引:0,他引:1
Miranda Schreurs Robert Percival 《环境科学研究》2006,19(Z1):133-142
环境危机通常通过推动采用预防危机反复出现,并提高社会对危机事件迅速有效反应能力的措施,而成为改善环境管理的催化剂.回顾了美国、欧洲与日本的几个环境危机事例以及国家调整性政策的改变.总结出进行环境危机管理工作应该考虑:①紧急准备要求国家与地方权力机构应该通过仔细监测工业用有害化学品的使用情况、使用结果与运输情况,以及可能带来的环境影响,了解其潜在的环境灾难.要求从事可能会带来环境危机活动的责任方证明其已经制定了综合有效的应急反应计划.②排放有害物质的责任方要负责承担补救环境与人类健康损失所花费的全额成本.建立有效的责任计划可以推动对预防环境危机措施方面的投资.③发生环境危机时,采取的最基本措施是及时将有关危机性质与范围等情况通告应急反应权力机构及公众.以提高应急反应能力,保持公众的信任.④吸取经验预防环境危机事件再发生.独立调查委员会要探索发生环境事故的原因,并为预防工作提供意见或建议.⑤政府与行业有责任采取措施保护公众免受与有害物质排放和其他有害活动相关的潜在危害;在事故发生时能及时反应并使损害达到最低;对人类健康与环境造的成损害提供赔偿. 相似文献
998.
IntroductionThispaperconcernstheadaptationandapplicationofamesoscalemeteorologicalmodelforgeneratingthewindfieldsandothermeteorologicalparametersforfuturestudiesofairpollutioninthecomplexterrainofHongKongSpecialAdministrativeRegion (HKSAR) .Themainarea… 相似文献
999.
1000.
Robert D Rowe Ralph C DArge David S Brookshire 《Journal of Environmental Economics and Management》1980,7(1):1-19
This paper reports on the development and application of an iterative bidding technique to examine proposed visibility reductions in the Four Corners Region of the southwest United States. The iterative bidding technique is a method to elicit honest bids for “goods” not priced in formal markets. Four issues associated with direct revelation of preferences for environmental goods are explored: (1) the establishment of linkages between the physical parameters of visibility and representation of the “good” called visibility to individuals for valuation purposes; (2) a systematic test for both observed and induced biases associated with the interative bidding technique; (3) replication of the results of previous experiments; and (4) reporting of empirical divergences between compensating and equivalent surplus measures of consumer surplus. 相似文献