全文获取类型
收费全文 | 724篇 |
免费 | 71篇 |
国内免费 | 302篇 |
专业分类
安全科学 | 73篇 |
废物处理 | 21篇 |
环保管理 | 85篇 |
综合类 | 552篇 |
基础理论 | 178篇 |
环境理论 | 1篇 |
污染及防治 | 116篇 |
评价与监测 | 33篇 |
社会与环境 | 21篇 |
灾害及防治 | 17篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 27篇 |
2020年 | 25篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 28篇 |
2016年 | 26篇 |
2015年 | 37篇 |
2014年 | 41篇 |
2013年 | 70篇 |
2012年 | 72篇 |
2011年 | 88篇 |
2010年 | 68篇 |
2009年 | 75篇 |
2008年 | 55篇 |
2007年 | 75篇 |
2006年 | 46篇 |
2005年 | 50篇 |
2004年 | 32篇 |
2003年 | 40篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1097条查询结果,搜索用时 328 毫秒
241.
ELISE F. GRANEK DANIEL R. BRUMBAUGH† SCOTT A. HEPPELL‡ SELINA S. HEPPELL‡ DAVID SECORD§ 《Conservation biology》2005,19(4):1008-1018
Abstract: In the first comprehensive reviews since 1969, two high-level reports on the status of U.S. marine ecosystems and resources have been released: that of the nongovernmental Pew Oceans Commission in 2003 and that of the congressionally mandated U.S. Commission on Ocean Policy in 2004 . Although the two commissions differed in the breadth and depth of their mandates, their findings on the state of our oceans and need for new management approaches are similar, and their major recommendations for science, governance, management and conservation, and education echo and reinforce each other. The history behind the two commissions and the structure and objectives of each remind us of the crucial roles conservation practitioners and scientists must play in the implementation of report recommendations. The reports suggest priorities for conservation practitioners to improve science, management, conservation, governance, and education to better manage and protect ocean resources and ecosystems. To redirect activities affecting the state of global marine resources, integrated research; education and outreach by terrestrial, aquatic, and marine conservation practitioners; and a clear definition of their roles in the implementation of recommendations is essential. Marine ecosystems provide a test case of society's ability to manage complexity in human and natural systems in an integrated manner, with extensive opportunities for participation by conservation practitioners from all disciplines. 相似文献
242.
Yorianta?Sasaerila Regine?Gries Gerhard?Gries Grigori?Khaskin Skip?King Stephen?Takács Hardi?) 《Chemoecology》2003,13(2):89-93
Summary. During peak calling activity by male oil palm bunch
moths, Tirathaba mundella Walker (Lepidoptera: Pyralidae), their
hairpencils, wings or entire body were extracted in hexane. Gas
chromatographic-electroantennographic detection (GC-EAD) analyses of
hair pencil extracts revealed four compounds that consistently elicited
responses from female antennae. The NMR spectrum of isolated compound 1,
and mass spectra and retention indices of compounds 1–4 suggested that
they were (3S,6S)-2,2,6-trimethyl-6-vinyl-tetrahydro-pyran-3-ol (1),
4-hydroxy-3-methoxy-benzaldehyde (2, vanillin),
6,10,14-trimethyl-2-pentadecanone (3), and
6,10,14-trimethyl-2-pentadecanol (4). Comparative GC and GC-MS analyses
of hair pencils extract and synthetic standards confirmed these
structural assignments. Moreover, comparative chromatography of
synthetic and hairpencil-isolated 1 on a Cyclodex-B column (which
separated the four stereoisomers with baseline resolution) revealed that
male T. mundella produce the SS-stereoisomer (SS-1). In field cage
bioassay experiments in Palembang, Indonesia, synthetic SS-1 and
vanillin in combination, but not singly, attracted female T. mundella.
SS-1 plus vanillin were as effective as male T. mundella in attracting
females. Compounds 3 and 4 did not enhance the blend's attractiveness.
Received October 11 2002; accepted March 14, 2003.
R1D="
Correspondence to: Gerhard Gries, email: gries@sfu.ca 相似文献
243.
用活性炭、浮石、陶粒和瓷环分别作为生物滴滤填料进行去除N2S恶臭气体的对比研究。活性炭和浮石对高效脱臭菌有强的吸附和固定作用,挂膜时间短,生物含量高而陶粒和瓷环固定期长,成膜较晚。在循环液流量为24L/h,气流量为0.5m^3/h,进气浓度在500mg/m^3的条件下,活性炭、浮石、陶粒和瓷环的成熟生物膜对H2S的去除率分别为99%、98%、95%和93%,从成膜到发生严重堵塞的生物增量的最大值分别是19.7、70.5、68.9、90.3mg/cm^3。试验对比结果表明,多孔浮石是优质的生物滴滤填料。 相似文献
244.
无苯酚培养基分离到的降酚菌多样性的分子分析 总被引:2,自引:0,他引:2
用3种不含苯酚的培养基(YPG、10%YPG和LB)从上海焦化厂废水处理系统(A2/O法)好氧池的悬浮污泥分离到24株降酚菌株.通过16SrDNAPCR扩增产物的限制性酶切分析(amplifiedribosomalDNArestrictionanalysis,ARDRA)、ERICPCR指纹图谱分析、多组分苯酚羟化酶大亚基(thelargestsubunitofthemulticomponentphenolhydroxylase,LmPH)基因的PCR扩增及16SrRNA基因测序的方法对这些降酚菌株进行表征.通过ARDRA分型,将这24株降酚菌株分为8个类型;利用ERICPCR可以将这24个菌株分为17种类型,说明同一ARDRA类型内菌株具有多样性.对17个ERIC类型代表菌株的16SrDNA扩增产物进行克隆并测序,测序结果在GenBank和RDP中进行比对.结果表明,与这17个代表菌株同源性最高的菌中,有6株是未见报道具有降酚功能的菌株.在这24株降酚菌中,有19株在苯酚含量为200mg/L的MP培养基中培养5d,苯酚降解率为20%左右,其余5株苯酚降解率达到100%,且均属于Rhodococcus属.本研究在降酚菌生物多样性上作了有益的探索.图2表1参20 相似文献
245.
用PCR方法扩增了一株石油降解菌株G5的16S rRNA基因全序列,并对其进行了克隆和测序.对该序列在GenBank中的BLAST结果表明,所有与该序列高度同源的序列都是假单胞菌的16S rRNA基因.其中假单胞菌的代表菌株Pseudomonas aeruginosa,P.fluoroscens,P .putida,P.syringae的16S rRNA基因序列与G5的16S rRNA基因序列同源性分别为93.4%,98.4%,96.3%,97.5%.对G5和其他39株假单胞菌的16S rRNA基因序列进行聚类分析,获得的系统发育树与RDP(Ribosomal Database Project)报道的系统发育树基本一致,其中菌株G5与5株P.chlororaphis聚类在一起.图2参7 相似文献
246.
Eugene P Seskin Robert J Anderson Robert O Reid 《Journal of Environmental Economics and Management》1983,10(2):112-124
In evaluating current environmental protection policy, economists often note that current regulations are more costly than necessary to meet environmental quality standards. While the a priori case is strong that current regulatory approaches are resulting in higher-than-necessary costs to attain environmental standards, there is relatively little empirical evidence to support this claim. The purpose of this paper is to supply some of the missing evidence by presenting the results of one study that assesses some of the potential savings associated with implementing economic, rather than command-and-control, regulatory approaches to abate one type of air pollution in one region of the country. Specifically, the paper examines the costs of meeting a prospective short-term standard for nitrogen dioxide under a range of alternative emissions control strategies for stationary sources of nitrogen oxide emissions in the Chicago Air Quality Control Region. The alternative strategies that are considered range from those that might result under current regulatory policy to those that economic policy approaches (such as emissions charges or marketable permits) are designed to implement. The analysis shows that the most efficient program of emissions controls may be more than an order of magnitude less costly than current regulatory strategies, and that economic approaches have additional advantages over more conventional regulatory approaches. 相似文献
247.
J. Wolstenholme 《黑龙江环境通报》1995,15(2):109-121
Sufficient information is now available from the literature to produce an audit of trisomy 16, in a theoretical cohort of 100 000 recognized pregnancies, from gametogenesis to term and onwards. Recent reports of premature separation of chromosome 16 bivalents during maternal meiosis I provide a novel mechanism for generation of this aneuploidy. Most, if not all, errors resulting in recognized mosaic and non-mosaic trisomy 16 pregnancies investigated using polymorphic DNA markers appear to originate at that stage. The incidence of this maternally derived trisomy 16 in the late first trimester is equivalent to 1500 cases in 100 000 recognized pregnancies, a figure which now corresponds very closely to the reinterpreted oogenesis data. Most trisomy 16 pregnancies are lost around 12 weeks' gestation, but of the order of 10 per cent (120–150 in this audit) undergo reduction to disomy, with 30 of these excluding aneuploidy from the fetal cell lineage (trisomic zygote rescue) and continuing into the second trimester. Maternal uniparental disomy (UPD) in one-third of this latter group is associated with loss later in pregnancy or severe intrauterine growth retardation, but can be compatible with a viable pregnancy. Adverse pregnancy outcomes are not restricted to those with UPD. Analysis of reports of confined placental mosaicism for chromosome 16 without associated UPD indicates that the presence of high levels of trisomic cells in the placenta alone consistently produces a more variable inhibition of fetal growth, which may also, in cases, be associated with late pregnancy loss. 相似文献
248.
An analysis of the energy inputs in corn, rice, sorghum, wheat, soybean, and millet in northeastern China indicates that most of the crops are produced with about one half the fossil energy inputs compared with those in the United States. The inputs of labor, however, are 10–100-fold greater than those in the United States. China also uses 85 to more than 500 h of horse power per hectare in producing its crop and this helps reduce the fossil energy inputs in crop production. A small increase in the use of machinery energy (3%) at appropriate times in the cropping systems could reduce labor inputs by about one third. 相似文献
249.
多环芳烃化合物菲分解菌的分离鉴定及分解特性研究 总被引:17,自引:0,他引:17
利用2,3-二差劲基联苯喷雾技术,从石油污染土壤中分离到2株菲降解菌。它们可以菲为惟一的碳源和能源良好地生长。在生理生化试验的基础上,利用16SrRNA(小核糖亚单位RNA序列)的方法鉴定这株菌为鞘氨醇单胞菌属细菌,这些菌对菲的降解性是通过在液体培养基内菌体的增加及底物的减少来证实的,静止细胞反应试验表明,这些菌除了菲以外还可降解其它芳烃化合物。 相似文献
250.
关于粘胶纤维生产中的废气治理 总被引:6,自引:0,他引:6
通过化纤厂粘胶纤维生产中废气治理实践,提出了粘胶纤维生产中废气治理的新工艺方法.利用该法H2S去除率达98%,CS2回收率接近70%,CS2外排浓度为30~40mg/m3,符合国家排放标准(40mg/m3). 相似文献