首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   107篇
  免费   3篇
  国内免费   1篇
安全科学   7篇
环保管理   22篇
综合类   27篇
基础理论   12篇
污染及防治   28篇
评价与监测   12篇
社会与环境   2篇
灾害及防治   1篇
  2021年   1篇
  2019年   2篇
  2018年   3篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2013年   16篇
  2012年   2篇
  2011年   5篇
  2010年   2篇
  2009年   4篇
  2008年   7篇
  2007年   3篇
  2006年   4篇
  2005年   5篇
  2004年   6篇
  2003年   3篇
  2002年   3篇
  2001年   2篇
  1998年   1篇
  1997年   4篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1985年   2篇
  1984年   1篇
  1976年   1篇
  1973年   2篇
  1972年   1篇
  1969年   1篇
  1934年   2篇
  1929年   2篇
  1928年   1篇
  1927年   2篇
  1926年   1篇
  1923年   1篇
  1922年   2篇
  1921年   1篇
  1919年   1篇
  1918年   2篇
  1917年   1篇
  1914年   1篇
  1913年   1篇
排序方式: 共有111条查询结果,搜索用时 15 毫秒
61.
The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e., dissolved organic matter (DOM), were identified using stable carbon and nitrogen isotopes and fatty acid biomarkers. We found that phytoplankton and its derived DOM from the adjacent open sea and from reef overlying water is not the main source of food for most of the sponges examined nor is bacterioplankton. Interestingly, dual stable isotope signatures (δ13Corg, δ15Norg) and fatty acid biomarkers appoint coral mucus and organic matter derived from crustose coralline algae (CCA) as probable food sources for encrusting sponges. Mucus-derived DOM may contribute up to 66% to the diet of examined sponges based on results of dual isotope mixing model analysis. The contribution of CCA (as purported representative for benthic algae) was smaller with values up to 31%. Together, mucus- and CCA-derived substrates contributed for 48–73% to the diet of sponges. The presence of the exogenous fatty acid 20:4ω6 in sponges, which is abundant in coral mucus of Madracis mirabilis and in CCA, highlights these reef-derived resources as sources of nutrition for DOM feeding cavity sponges. The relatively high concentrations of exogenous 20:4ω6 in all sponges examined supports our hypothesis that the bulk of the food of the cavity sponge community is reef-derived. Our results imply that cavity sponges play an important role in conserving food and energy produced within the reef.  相似文献   
62.
Environmental Modeling & Assessment - Costa Rica has set a very ambitious Nationally Determined Contribution (NDC). Despite the low-carbon footprint of its power sector, the goal set in its NDC...  相似文献   
63.
A case of prenatally detected partial trisomy 15 and 16 is reported. Amniocentesis was performed at 14 weeks' gestation because a 6-mm nuchal translucency was detected on a dating ultrasound evaluation. Karyotype from amniocytes was suspect of an aberration concerning a marker chromosome. FISH analysis demonstrated that this marker chromosome was a der(15). A maternal chromosomal rearrangement t(15;16)(q13;p13.2) was confirmed. At birth, the proband was severely hydropic and had dysmorphic features, which included hypertelorism, micrognathia, incomplete separation of the maxilla and mandible, hyperflexed hands with overlapping fingers, hyposegmented right lung, and a single umbilical artery. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
64.
65.
66.
ABSTRACT: A strategy is developed for making seasonal water supply forecasts in real time. It links the traditional regression based forecasting techniques to real-time data acquired by systems such as the Soil Conservation Service SNOTEL and the U.S. Bureau of Reclamation Hydromet networks. The concept is based on interpolating between the forecast values obtained by using real-time data in the forecast equations that bracket the real time. Different interpolation procedures were examined and the procedure for calculating confidence intervals about the forecast estimates is developed. The entire conceptual procedure is demonstrated using data from the Reynolds Creek, Idaho, experimental watershed maintained by the USDA-ARS Northwest Watershed Research Center in Boise, Idaho.  相似文献   
67.
Although previous research has found weak support for the model of stressful work ‘spilling over’ to negative coping responses during nonwork hours, we argue that a variety of conceptual and methodological problems may partially explain the weak and inconsistent findings. Two important shortcomings are inadequately specified models and a failure to consider nonescapist responses to job-related stress. We therefore propose that there may be escapist (i.e. increased drinking, working through job dissatisfaction for those who believe that alcohol consumption is an effective means to reduce stress) and nonescapist (i.e. decreased drinking for those who are dissatisfied with their jobs but do not believe alcohol is an effective coping strategy) responses to work stress. These hypotheses were tested on a sample of 972 production workers in the Pacific northwest. Results show moderate support for the existence of both escapist and nonescapist responses to job-related stresses. © 1998 John Wiley & Sons, Ltd.  相似文献   
68.
Ambient ammonia monitoring using Ogawa passive samplers was conducted in the Four Corners area and eastern Oklahoma, USA during 2007. The resulting data will be useful in the multipollutant management of ozone, nitrogen oxides, and visibility (atmospheric regional haze) in the Four Corners area, an area with growing oil/gas production and increasing coal-based power plant construction. The passive monitoring data also add new ambient ammonia concentration information for the U.S. and will be useful to scientists involved in present and future visibility modeling exercises. Three week integrated passive ammonia samples were taken at five sites in the Four Corners area and two sites in eastern Oklahoma from December, 2006 through December, 2007 (January, 2008 for two sites). Results show significantly higher regional background ammonia concentrations in eastern Oklahoma (1.8 parts per billion (ppb) arithmetic mean) compared to the Four Corners area (0.2 ppb arithmetic mean). Annual mean ammonia concentrations for all Four Corners area sites for the 2007 study ranged from 0.2 ppb to 1.5 ppb. Peak ambient ammonia concentrations occurred in the spring and summer in both areas. The passive samplers deployed at the Stilwell, Oklahoma site compared favorably with other passive samplers and a continuous ammonia monitoring instrument.  相似文献   
69.
Organic matter (OM) remineralization may be considered a key function of the benthic compartment of marine ecosystems and in this study we investigated if the input of labile organic carbon alters mineralization of indigenous sediment OM (OM priming). Using 13C-enriched diatoms as labile tracer carbon, we examined shallow-water sediments (surface and subsurface layers) containing organic carbon of different reactivity under oxic versus anoxic conditions. The background OM decomposition rates of the sediment used ranged from 0.08 to 0.44 μmol C mlws−1 day−1. Algal OM additions induced enhanced levels of background remineralization (priming) up to 31% and these measured excess fluxes were similar to mineralization of the added highly degradable tracer algal carbon. This suggests that OM priming may be important in marine sediments.  相似文献   
70.
We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products 131I, 132I, 132Te, 134Cs, and 137Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity from radionuclides attached to particulate matter amounted to 4.4 ± 1.3 mBq m−3 of 131I on 19-20 March.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号