全文获取类型
收费全文 | 579篇 |
免费 | 37篇 |
国内免费 | 58篇 |
专业分类
安全科学 | 95篇 |
废物处理 | 24篇 |
环保管理 | 98篇 |
综合类 | 348篇 |
基础理论 | 32篇 |
污染及防治 | 50篇 |
评价与监测 | 12篇 |
社会与环境 | 4篇 |
灾害及防治 | 11篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 24篇 |
2019年 | 17篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 19篇 |
2015年 | 24篇 |
2014年 | 24篇 |
2013年 | 23篇 |
2012年 | 34篇 |
2011年 | 43篇 |
2010年 | 18篇 |
2009年 | 24篇 |
2008年 | 30篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 12篇 |
2003年 | 23篇 |
2002年 | 18篇 |
2001年 | 23篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有674条查询结果,搜索用时 585 毫秒
401.
建立了地铁实体模型,开展了地铁火灾实验研究,测量了站台与站厅之间的楼梯处的速度和温度等火灾参数。同时利用火灾动力学模拟程序软件对地铁站台火灾进行了数值模拟,研究了地铁站台和站厅连接楼梯处温度和烟气速度的变化趋势,并与实验结果作了对比分析,验证了数值模拟结果的有效性。研究结果可为有效控制烟气在地铁中的蔓延和组织人员疏散提供技术支持。 相似文献
402.
Frans J. Los Cardi van den Berg Hajo I. J. Wildschut Helen Brandenburg Nicolette S. den Hollander Ernst M. Schoonderwaldt Leen Pijpers Robert Jan H. Galjaard Diane Van Opstal 《黑龙江环境通报》2001,21(13):1150-1158
First-trimester chorionic villus sampling has not reached the popularity of second-trimester amniocentesis in prenatal cytogenetic diagnosis, in contrast to initial expectations. We investigated whether a difference inthe diagnostic performances of cytogenetic investigation in amniotic fluid (AF) cells and chorionic villi in favour of AF-cells might justify this. Diagnostic performance was measured as laboratory failure rate, karyotype quality (G-band score, rate of follow-up samples, rate of wrong diagnoses), and karyotype representativity (rate of follow-up samples, rate of wrong diagnoses). From 1993–1999, 11 883 AF-samples were investigated (AF-cells). In chorionic villi, short term culture preparations solely were karyotyped from 1993–1996 (n=3499) (STC-villi), short and long-term culture preparations simultaneously provided a sufficient amount of tissue being available from 1997 onwards (n=1829) ((STC+LTC)-villi). Laboratory failure rates were the same after amniocentesis (0.40%) and chorionic villus sampling (0.50%). G-band scores (mean±SD) were equal in AF-cells (373±38.1) and LTC-villi (364±32.6) but significantly lower in STC-villi (311±34.6) (p=0.001). Follow-up sampling rates because of quality reasons were the same in AF-cells (0.14%), STC- villi (0.13%) and (STC+LTC)-villi (0.11%). Two wrong diagnoses turned up among AF-cells. Follow-up sampling rates because of representativity reasons differed significantly between AF-cells (0.10%), (STC+LTC)-villi (1.31%), and STC-villi (1.99%) (p<0.001). However, the ratios of the total numbers of follow-up samples and uncertain or abnormal cytogenetic results in STC, and (STC+LTC)-villi at cytogenetic risks ⩾3% (0.132 and 0.160, respectively) were equal to that in AF-cells at risks <3% (0.155). Two wrong diagnoses were made in STC-villi. Diagnostic performance improved in the rank order of STC-villi, (STC+LTC)-villi and AF-cells. At cytogenetic risks ⩾3%, (STC+LTC)-villi showed a diagnostic performance equal to that in AF-cells. This might justify a selective use of chorionic villus sampling. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
403.
地球内部存在大量挥发份,它们自深层逸出过程中一般呈趋临界流体状态。由于超临界流体的特殊性质,它们的运移极有可能与地下的油气藏发生联系,甚至对油气的富集、运移与成藏的各个演化过程可能都有不可忽视的影响。 相似文献
404.
ABSTRACT: Wind driven raindrop tracking is used to investigate the microscale redistribution of wind driven rainfalls in street canopies by combining a Eulerian wind flow model and a Lagrangian raindrop tracking model. The former conducts large eddy simulations of the turbulent flows in street canopies, and the latter performs raindrop trajectory calculations by releasing a large number of raindrops into the computational domain. The wind speed model is verified with available wind tunnel measurement. Twenty sets of simulations are carried out for various building configurations and driving rain angles. The simulated results show that the trajectories of smaller raindrops are more slanting and more influenced by the multibuilding perturbed flow field. Impingement of raindrops on the building envelope increases from bottom to top. The height of the front building is a significant factor affecting wind driven rain redistribution. Distinct nonuniform spatial rainfall distributions are found for scenarios with high building configurations and low driving rain angles. The simulated results are further integrated to assess the effect of real raindrop size distributions by weighing the volumetric fraction of a range of drop sizes. There is about 10 percent variation in spatial extent of street canopies. An overall 5 to 17.4 percent increase of the rainfall amount in the upwind zone is observed. 相似文献
405.
406.
Laura Braida Sergio Crovella Michele Boniotto Ariella Luchesi Umberto de Vonderweid Bruno Casetta Antonio Amoroso 《黑龙江环境通报》2001,21(7):543-546
We describe a quantitative, rapid, sensitive and reproducible tandem mass spectrometry (MSMS) method for the one-step detection of aminoacid (AAs) and acylcarnitine (ACs) concentrations in amniotic fluid. This technology is quicker and more sensitive than other methods used to date since it is possible to determine very low AA and AC concentrations in samples simultaneously in a single run. The high degree of automation allows a large number of pregnancies to be screened for metabolic defects in a very short time. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
407.
408.
The Bhopal disaster was a gas leak incident in India, considered the world's worst industrial disaster happened around process facilities. Nowadays the process facilities in petrochemical industries have becoming increasingly large and automatic. There are many risk factors with complex relationships among them. Unfortunately, some operators have poor access to abnormal situation management experience due to the lack of knowledge. However these interdependencies are seldom accounted for in current risk and safety analyses, which also belonged to the main factor causing Bhopal tragedy. Fault propagation behavior of process system is studied in this paper, and a dynamic Bayesian network based framework for root cause reasoning is proposed to deal with abnormal situation. It will help operators to fully understand the relationships among all the risk factors, identify the causes that lead to the abnormal situations, and consider all available safety measures to cope with the situation. Examples from a case study for process facilities are included to illustrate the effectiveness of the proposed approach. It also provides a method to help us do things better in the future and to make sure that another such terrible accident never happens again. 相似文献
409.
Brent D. Kerger Russell Gerads Hakan Gurleyuk Ania Urban Dennis J. Paustenbach 《毒物与环境化学》2015,97(9):1145-1163
Inductively coupled plasma with mass spectrometric detection (ICP-MS) has been used for clinical analysis of cobalt (Co) due to its sensitivity and specificity; however, media-specific validation studies are lacking. This study provides data on performance variables affecting differences between selected analytical platforms (Perkin Elmer and Agilent), tissue sample preparation, storage, and interferences affecting measurements in whole blood, serum, and synovial fluid. The limits of detection (LOD) range from 0.2–0.5 µg/L in serum and synovial fluid, and 0.6–1.7 µg Co/L in whole blood. The Agilent platform with collision reaction cell is more sensitive, while the Perkin Elmer platform with dynamic reaction cell demonstrates more polyatomic interferences near the LOD for serum and whole blood. Split sample analysis showed good accuracy, precision, and reproducibility between serum Co measurements using acid digestion or detergent dilution preparations for persons with metal hip implants or following supplement intake. The results demonstrated reliability of the ICP-MS methodology across the two analytical platforms and between two commercial laboratories for Co concentrations above 5 µg Co/L, but digestion procedures and polyatomic interferences may affect measurements in some media at lower concentrations. These studies validate the described ICP-MS methodology for clinical purposes with precautions at low cobalt concentrations (<5 µg Co/L). 相似文献
410.
This paper describes an experimental investigation of turbulent flame propagation in propane-air mixtures, and in mechanical suspensions of maize starch dispersed in air, in a closed vessel of length 3.6 m and internal cross-section 0.27 m × 0.27 m. The primary motivation for the work is to gain improved understanding of turbulent flame propagation in dust clouds, with a view to develop improved models and methods for assessing explosion risks in the process and mining industries. The study includes computational fluid dynamics (CFD) simulations with FLACS and DESC, for gas and dust explosions respectively. For initially quiescent propane-air mixtures, FLACS over-predicts the rate of combustion for fuel-lean mixtures, and under-predicts for fuel-rich mixtures. The simulations tend to be in better agreement with the experimental results for initially turbulent gaseous mixtures. The experimental results for maize starch vary significantly between repeated tests, but the subset of tests that yields the highest explosion pressures are in reasonable agreement with CFD simulations with DESC. 相似文献