全文获取类型
收费全文 | 11446篇 |
免费 | 4364篇 |
国内免费 | 26513篇 |
专业分类
安全科学 | 1131篇 |
废物处理 | 302篇 |
环保管理 | 1633篇 |
综合类 | 28905篇 |
基础理论 | 2791篇 |
环境理论 | 7篇 |
污染及防治 | 5610篇 |
评价与监测 | 1522篇 |
社会与环境 | 163篇 |
灾害及防治 | 259篇 |
出版年
2023年 | 23篇 |
2022年 | 23篇 |
2021年 | 29篇 |
2020年 | 616篇 |
2019年 | 1876篇 |
2018年 | 2041篇 |
2017年 | 2050篇 |
2016年 | 1812篇 |
2015年 | 2246篇 |
2014年 | 2875篇 |
2013年 | 3326篇 |
2012年 | 2966篇 |
2011年 | 2498篇 |
2010年 | 2282篇 |
2009年 | 2252篇 |
2008年 | 1912篇 |
2007年 | 1976篇 |
2006年 | 1384篇 |
2005年 | 1066篇 |
2004年 | 997篇 |
2003年 | 785篇 |
2002年 | 634篇 |
2001年 | 636篇 |
2000年 | 746篇 |
1999年 | 629篇 |
1998年 | 494篇 |
1997年 | 457篇 |
1996年 | 510篇 |
1995年 | 464篇 |
1994年 | 319篇 |
1993年 | 246篇 |
1992年 | 313篇 |
1991年 | 299篇 |
1990年 | 265篇 |
1989年 | 226篇 |
1988年 | 183篇 |
1987年 | 100篇 |
1986年 | 108篇 |
1985年 | 86篇 |
1984年 | 83篇 |
1983年 | 77篇 |
1982年 | 93篇 |
1981年 | 81篇 |
1980年 | 26篇 |
1979年 | 30篇 |
1978年 | 28篇 |
1977年 | 29篇 |
1976年 | 14篇 |
1972年 | 16篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
251.
Grace B. Villamor Robert Gilmore Pontius Jr. Meine van Noordwijk 《Regional Environmental Change》2014,14(2):825-834
This paper examines the size and intensity of changes among five land categories during the two time intervals in a region of Indonesia that is pioneering negotiations concerning reducing emissions from deforestation and forest degradation (REDD). Maps at 1973, 1993, and 2005 indicate that land-cover change is accelerating, while carbon loss is decelerating in Jambi Province, Sumatra. Land dynamics have shifted from Forest loss during 1973–1993 to Agroforest loss during 1993–2005. Forest losses account for most reductions in aboveground carbon during the both time intervals, but Agroforest plays an increasingly important role in carbon reductions during the more recent interval. These results provide motivation for future REDD policies to count carbon changes associated with all influential land categories, such as Agroforests. 相似文献
252.
2008年江苏持续性降雪中的水汽和动力抬升机制分析 总被引:1,自引:0,他引:1
2008年1月下旬江苏省出现了历史罕见的持续性暴雪过程,研究发现,降雪量的大小与低空急流的日变化相对应,暴雪过程中700 hPa西南急流对水汽的输送起着重要的作用,作为大尺度天气系统,700 hPa急流的加速发生在降雪量增大之前,其值阈大小与6 h降雪量之间没有对应关系,急流减弱在暴雪结束以后;降雪的发生和发展与南北风的增大和冷暖平流有关,低层偏北风作为冷垫对暖湿气流的抬升和水汽的凝结起到了一定的作用;江苏降雪过程中水汽主要来源于700~500 hPa,低层东风气流对黄海南部的水汽输送非常有限;强降雪的发生与700 hPa水汽通量散度相对应,水汽通量散度辐合增大,降雪量增大;在降雪过程中垂直运动对降雪量的大小有很好的指示意义。 相似文献
253.
Gebbink WA Letcher RJ Burgess NM Champoux L Elliott JE Hebert CE Martin P Wayland M Weseloh DV Wilson L 《Environment international》2011,37(7):1175-1182
In the present study, we identified and examined the spatial trends, sources and dietary relationships of bioaccumulative perfluorinated sulfonate (PFSA; C(6), C(8), and C(10) chain lengths) and carboxylate (PFCA; C(6) to C(15) chain lengths) contaminants, as well as precursor compounds including several perfluorinated sulfonamides, and fluorotelomer acids and alcohols, in individual eggs (collected in 2008) from four gull species [glaucous-winged (Larus glaucescens), California (Larus californicus), ring-billed (Larus delawarensis) and herring (Larus argentatus) gulls] from 15 marine and freshwater colony sites in provinces across Canada. The pattern of PFSAs was dominated by perfluorooctane sulfonate (PFOS; >89% of ΣPFSA concentration) regardless of egg collection location. The highest ΣPFSA concentrations were found in the eggs collected in the urbanized areas in the Great Lakes and the St. Lawrence River area [Big Chicken Island 308 ng/g ww, Toronto Harbour 486 ng/g ww, and Ile Deslauriers (HG) 299 ng/g ww]. Also, eggs from all freshwater colony sites had higher ΣPFSA concentrations, which were significant (p<0.05) in many cases, compared to the marine sites with the exception of the Sable Island colony in Atlantic Canada off the coast of Nova Scotia. C(6) to C(15) chain length PFCAs were detected in the eggs, although the pattern was variable among the 15 sites, where PFUnA and PFTrA dominated the pattern for most colonies. Like the ΣPFSA, the highest concentrations of ΣPFCA were found in the eggs from Big Chicken Island, Toronto Harbour, Ile Deslauriers (HG), and Sable Island, although not all freshwater sites had higher concentrations compared to marine sites. Dietary tracers [δ(15)N and δ(13)C stable isotopes (SIs)] revealed that PFSA and PFCA exposure is colony dependent. SI signatures suggested that gulls from most marine colony sites were exposed to PFCs via marine prey. The exception was the Mandarte Island colony in Pacific British Columbia, where PFSA and PFCA exposure appeared to be via terrestrial and/or freshwater prey consumption. The same was true for the freshwater sites where egg SIs suggested both aquatic and terrestrial prey consumption as the source for PFC exposure depending on the colony. Both aquatic (marine and freshwater) and terrestrial prey are likely sources of PFC exposure to gulls but exposure scenarios are colony-specific. 相似文献
254.
Wood samples impregnated with inorganic wood preservatives containing the elements arsenic, boron, chromium, copper, fluorine, and/or zinc were burned in a furnace. Three different kinds of ash were collected: furnace, boiler, and so-called fly ash. Analyses showed that the ash contained large amounts of elements originating from the inorganic wood preservatives. Further interest was focused on the leachability of the above-mentioned elements. For this purpose a laboratory batch leaching test according to the German Standard DIN 38 414 part 4 was chosen. The results indicate that the leachability is in a range where the release of these elements to the environment from deposited ash can be considered as detrimental. 相似文献
255.
The use of a reference compound to quantify the sorption of nonpolar organic chemicals is proposed. This is because organic carbon normalized sorption coefficients (KOC) do appear to be dependent on the type of sediment, and are thus not generally applicable to characterize the sorption properties of chemicals. Therefore, in this paper the hypothesis that nonpolar chemicals sorb in a constant ratio, independent of the sediment, has been investigated. Evidence for this hypothesis is shown with data from the literature. This enables one to compare sorption properties of nonpolar compounds on different sediments, if the differences between the sediments are normalized with a reference chemical rather than with the organic carbon content. Sediments with an organic carbon content of less than 0.1% seem to be unsuitable, because the compounds do not sorb mainly on the organic carbon, but also on other parts of the sediment. Sorption coefficients of compounds with aqueous solubilities in the μg per liter range or octan-1-ol water partition coefficients of more than 105 are strongly influenced by the experimental techniques used. For these compounds the sorption coefficients measured by different techniques are less comparable. To enable comparison of sorption coefficients of hydrophobic chemicals, the use of a chlorobenzene as a reference compound in sorption experiments is suggested. 相似文献
256.
Dioxins and furans were detected in emissions from eight medical waste incinerators tested in California. Total uncontrolled emissions ranged from 363 to 11, 811 nanograms per dry standard cubic meter. The most effective of three wet scrubbers achieved an emissions control efficiency of 95 percent for total PCDD and PCDF. A baghouse was less than 30 percent efficient in removing PCDD and PCDF from the incinerator emissions. 相似文献
257.
Ralf Schulz Maike Hauschild Markus Ebeling Jakob Nanko-Drees Joem Wogram Mathias Liess 《Chemosphere》1998,36(15):3071-3082
A field method is described, which allows the qualitative estimation of pesticide contamination in the edgeof-field runoff. The method employs cheap and easy-to-use runoff sampling bottles, which were installed in an agricultural stream catchment over a period of three growing seasons. During this time 18 runoff events were detected, in nine of which insecticide contamination was measured (maximum concentrations: lindane 0.7 μg l−1 and 12.7 μg kg−1, parathion 20 μg l−1 and 728 μg kg−, fenvalerate 18.4 μg 1-1 and 924 μg kg−1). These insecticides were detected mainly as particle-bound chemicals. On about 80 % of the occasions the presence or absence of runoff measured in the field was in agreement with a simulation of runoff presence or absence using the runoff model KINEROS. 相似文献
258.
Rainer Brüggemann Andreas Kaune Laszlo Zelles Anton Hartmann Christian Steinberg 《Umweltwissenschaften und Schadstoff-Forschung》1995,7(5):265-274
Die ?kotoxikologie mu? sich mit biologischen Systemen und ihren Antworten auf schadstoffinduzierten Stre? auseinandersetzen.
Die hierzu verwendete experimentelle Technik eilt dabei den M?glichkeiten dynamischer, proze?orientierter mathematischer Modellierung
weit voraus.
In dieser methodisch orientierten Arbeit werden Techniken aus der mathematischen Disziplin der Verbandstheorie vorgestellt,
die eine Datenanalyse unter den Aspekten vergleichender Bewertung erlauben. Wichtige Ergebnisse sind dabei
相似文献
– | • Aussagen zur Diversit?t mikrobieller Systeme (soweit durch die hier verwendeten Muster von vier Phospholipidfetts?uren erfa?bar), |
– | • Analysen ordinaler Abh?ngigkeiten sowie |
– | • komprimierte Darstellung komplexer Befunde im Zusammenhang mit der Toxizit?t von Huminstoff-Chemikalien-Systemen. |
259.
260.
Astrid Wetzel Gabriela Klante D. Werner 《Umweltwissenschaften und Schadstoff-Forschung》1991,3(5):266-271
Im Zusammenhang mit der Umweltchemikalienprüfung und der Untersuchung und Kontrolle kontaminierter B?den besteht gro?er Bedarf
an Testverfahren mit h?heren Pflanzen, die schnell, einfach und preisgünstig durchzuführen sind und bereits bestehende Testverfahren
nach OECD- und BBA-Richtlinien sinnvoll erg?nzen k?nnen. Dieser Beitrag stellt einen Biotoxizit?tstest vor, der die Nodulation
in der Leguminosen-Kn?llchen-Symbiose als sensiblen Wirkungsparameter für die Belastung mit polyzyklischen aromatischen Kohlenwasserstoffen
(PAK) benutzt. Fremdstoff, Pflanze und Mikroorganismus werden dabei auf einer festen Matrix in Kontakt miteinander gebracht;
das axenische System erlaubt die Untersuchung der Fremdstoffwirkung sowohl auf den Gesamtorganismus Pflanze, als auch auf
die Interaktion von Pflanze und Mikroorganismus (Kn?llchenbildung). In Dose-Response-Versuchen zeigte sich der Wirkungsparameter
Nodulation, gemessen als Anzahl Wurzelkn?llchen pro Pflanze, sensibler als andere pflanzliche Wachstumsparameter.
There is great need for toxicity tests with higher plants for the investigation and monitoring of chemicals in the environment
— especially for tests which are quick, easy, and inexpensive. Such tests should add to and improve current guidelines, e.g.,
OECD- and BBA-Guidelines. This article describes the nodulation of leguminous plants withRhizobium bacteria used in a bioassay with polycyclic aromatic hydrocarbons (PAH). Plants growing on a solid medium were exposed simultaneously
to bacteria and PAH. This axenic culture system allows to observe the impact of PAH on plant growth and the interaction between
plant and bacteria (nodulation). Dose-response-experiments indicated that nodulation measured as number of nodules per plant,
was more sensitive to the inhibition by PAH than other plant growth parameters. 相似文献