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   211篇
  免费   3篇
安全科学   20篇
废物处理   27篇
环保管理   23篇
综合类   30篇
基础理论   50篇
污染及防治   33篇
评价与监测   17篇
社会与环境   12篇
灾害及防治   2篇
  2023年   2篇
  2022年   2篇
  2021年   3篇
  2020年   4篇
  2019年   4篇
  2018年   4篇
  2017年   2篇
  2016年   8篇
  2015年   7篇
  2014年   9篇
  2013年   15篇
  2012年   11篇
  2011年   12篇
  2010年   10篇
  2009年   15篇
  2008年   10篇
  2007年   13篇
  2006年   8篇
  2005年   6篇
  2004年   5篇
  2003年   11篇
  2002年   11篇
  2001年   9篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   4篇
  1994年   7篇
  1993年   2篇
  1992年   3篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1976年   1篇
  1973年   1篇
  1972年   1篇
  1970年   2篇
  1966年   1篇
  1965年   1篇
排序方式: 共有214条查询结果,搜索用时 31 毫秒
131.
A case of dilated coronary sinus with persistent left superior vena cava diagnosed at 33 weeks in a fetus with trisomy 18 is reported. The features of this cardiac anomaly on prenatal ultrasonography and its association with trisomy 18 are discussed. Published in 2003 John Wiley & Sons, Ltd.  相似文献   
132.
133.
134.
135.
A simple and dynamic pharmacokinetic model was developed to predict bioconcentration of organic contaminants in earthworms. The model was parameterized experimentally by placing Lumbricus terrestris in soil contaminated with 200 μg/cm2 of malathion. The toxicokinetics of malathion uptake, depuration, and degradation in soil is measured. After parameterization, the model was able to accurately predict the bioconcentration factor of malathion at steady state. Sensitivity analyses were performed and the rate of absorption was determined to be the most sensitive parameter. Varying the rate of malathion elimination from earthworm tissues, malathion degradation, and the amount of malathion applied to the soil by 25-fold did not result in the bioconcentration of malathion. An increase in the rate of malathion absorption into earthworm tissues by 25-fold did result in bioconcentration. Previously published pharmacokinetic studies on xenobiotics with log K ow values ranging up to 8.05 were used to test the predictive capacity of the model. The model was able to predict from 83% to 105% of the experimentally derived bioconcentration factors.  相似文献   
136.
Many researchers have used the insider–outsider distinction when discussing employment relationships (e.g., Graen & Scandura, 1987; Pfeffer & Baron, 1988). However, there is no known empirical research directly assessing employees' perceptions of their status as organizational insiders. This article is intended as an initial step to theoretically and empirically explore the concept of perceived insider status (PIS). First, we build theoretical arguments describing how organizations may differentiate between insider and outsider employees, leading to differences in perceptions of insider status. We then hypothesize and show empirical evidence that contrasts, but relates, actual inclusion and perceived organizational support to PIS. We subsequently examine two types of discretionary employee behavior, altruism and production deviance, as potential consequences of PIS. Our results suggest that both actual inclusion, as well as perceived insider status, have implications for organizational functioning via discretionary employee behaviors. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
137.
Picocyanobacteria, which specifically excited the phycobilin pigments by green light, were numerically counted under an epifluorescence microscope in the Kuroshio and the Oyashio between 1 and 9 July 1983, and in coastal waters between 10 and 12 August 1983 off Japan. The fluorescence, and the various morphological and chemical characters of the picocyanobacteria were evaluated by using monospecific strains isolated from the study area. Plasma volume determined on the epifluorescence microscopic photographs was converted into cellular organic carbon using a relation obtained from the isolates. Percentages of the picocyanobacteria biomass in terms of cellular carbon ranged between 8.3 to 79.4% of the total picophytoplankton (<3 m), and between 4.7 to 46.4% of the total phytoplankton. The larger percentages of the picocyanobacteria occurred consistently in low chlorophyll waters.  相似文献   
138.
Prenatal diagnosis choices were reviewed in 473 women who presented for genetic counselling prior to 11 weeks' gestation for the indication of advanced maternal age. Group A consisted of 336 patients who were unaware of a possible association between chorionic villus sampling (CVS) and limb defects. Group B consisted of 137 patients who were provided this information. Fifty-one per cent of patients in group A and 45 per cent of patients in group B chose CVS. This difference was not significant by χ2 analysis (P = 0·7). Patterns of prenatal diagnosis procedure utilization from 1987 to 1992 revealed a significant reduction in CVS utilization accompanied by a corresponding increase in amniocentesis after the association between CVS and limb defects was publicized. Referrals for CVS counselling also significantly declined. However, acceptance rates did not change for those patients who received genetic counselling. First-trimester genetic counselling, including a discussion regarding a possible association between CVS and limb defects, helps patients make informed decisions concerning prenatal diagnosis options, and, in our population, resulted in no change in CVS acceptance rates.  相似文献   
139.
We investigated relationships among North Atlantic Tigriopus brevicornis populations and their relationships to Mediterranean T. fulvus and North American T. californicus, using crossing experiments and mitochondrial DNA sequencing. All T. brevicornis populations tested were interfertile, while interspecific crosses produced either no offspring or offspring that did not survive past the larval stage, with the exception of a few T. brevicornis × T. californicus crosses that produced mature adults. DNA sequencing of a fragment of mitochondrial cytochrome oxidase I (COI) showed that samples of T. brevicornis from Iceland, the Faroes, Ireland, Scotland and Nova Scotia formed a single shallow clade. In contrast, T. brevicornis from more southern populations in France and Portugal formed a clade with substantially greater branch lengths. Tigriopus brevicornis was monophyletic, and T. brevicornis plus Mediterranean T. fulvus were together also monophyletic. The phylogeography of T. brevicornis closely mirrored that found in T. californicus, with substantially reduced interpopulation divergence at northern latitudes. The known distribution of T. brevicornis in Iceland and the Faroes is shown and dispersal mechanisms and habitat selection briefly discussed.  相似文献   
140.
Biodegradation experiments of various polycyclic aromatic hydrocarbons were studied with mixed bacteria culture under aerobic conditions. An easy‐to‐handle clean‐up procedure was developed for PAH and their metabolites simultaneously as well as a gc‐ms‐method to identify and quantify these compounds.

Anthracene and dibenzothiophene are completely degradable in an aqeous system, whereas biodegradation of benzo(k)fluoranthene and benzo(h)quinoline is possible only in an oil‐in‐water‐system with dodecane as cosubstrate. No degradation of nitronaphthalene was observed in aqueous systems. New metabolites are 2,3‐dihydroxybenzothiophene, hydroxybenzothiophenecarbonic acid and benzothiophenequinone for dibenzothiophene and hydroxyfluoranthenic acid for benzo(k)flouranthene. Whereas the former metabolites are degradable under the experimental conditions, the latter accumulates during the degradation experiment.

The results are important for microbiological wastewater treatment, since knowledge of biodegradation processes is indespensable for the successful treatment of PAH‐containing wastewater.  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