全文获取类型
收费全文 | 19284篇 |
免费 | 137篇 |
国内免费 | 178篇 |
专业分类
安全科学 | 425篇 |
废物处理 | 917篇 |
环保管理 | 1918篇 |
综合类 | 3951篇 |
基础理论 | 4374篇 |
环境理论 | 10篇 |
污染及防治 | 5293篇 |
评价与监测 | 1576篇 |
社会与环境 | 1053篇 |
灾害及防治 | 82篇 |
出版年
2023年 | 109篇 |
2022年 | 275篇 |
2021年 | 246篇 |
2020年 | 136篇 |
2019年 | 170篇 |
2018年 | 368篇 |
2017年 | 331篇 |
2016年 | 530篇 |
2015年 | 367篇 |
2014年 | 666篇 |
2013年 | 1474篇 |
2012年 | 747篇 |
2011年 | 911篇 |
2010年 | 715篇 |
2009年 | 723篇 |
2008年 | 845篇 |
2007年 | 866篇 |
2006年 | 785篇 |
2005年 | 680篇 |
2004年 | 602篇 |
2003年 | 587篇 |
2002年 | 552篇 |
2001年 | 689篇 |
2000年 | 432篇 |
1999年 | 304篇 |
1998年 | 168篇 |
1997年 | 183篇 |
1996年 | 181篇 |
1995年 | 223篇 |
1994年 | 205篇 |
1993年 | 146篇 |
1992年 | 183篇 |
1991年 | 183篇 |
1990年 | 180篇 |
1989年 | 152篇 |
1988年 | 166篇 |
1987年 | 101篇 |
1986年 | 131篇 |
1985年 | 135篇 |
1984年 | 123篇 |
1983年 | 120篇 |
1982年 | 124篇 |
1981年 | 120篇 |
1979年 | 104篇 |
1978年 | 102篇 |
1974年 | 105篇 |
1967年 | 106篇 |
1966年 | 96篇 |
1964年 | 117篇 |
1962年 | 97篇 |
排序方式: 共有10000条查询结果,搜索用时 70 毫秒
991.
Kusum Komal Karati G. Vineetha N. V. Madhu P. Anil M. Dayana B. K. Shihab A. I. Muhsin C. Riyas T. V. Raveendran 《Environmental monitoring and assessment》2017,189(12):653
El Niño, an interannual climate event characterized by elevated oceanic temperature, is a prime threat for coral reef ecosystems worldwide, owing to their thermal threshold sensitivity. Phytoplankton plays a crucial role in the sustenance of reef trophodynamics. The cell size of the phytoplankton forms the “master morphological trait” with implications for growth, resource acquisition, and adaptability to nutrients. In the context of a strong El Niño prediction for 2015–2016, the present study was undertaken to evaluate the variations in the size-structured phytoplankton of Kavaratti reef waters, a major coral atoll along the southeast coast of India. The present study witnessed a remarkable change in the physicochemical environment of the reef water and massive coral bleaching with the progression of El Niño 2015–2016 from its peak to waning phase. The fluctuations observed in sea surface temperature, pH, and nutrient concentration of the reef water with the El Niño progression resulted in a remarkable shift in phytoplankton size structure, abundance, and community composition of the reef waters. Though low nutrient concentration of the waning phase resulted in lower phytoplankton biomass and abundance, the diazotroph Trichodesmium erythraeum predominated the reef waters, owing to its capability of the atmospheric nitrogen fixation and dissolved organic phosphate utilization. 相似文献
992.
Lino J. Alvarez-Vázquez Gerardo Casal Aurea Martínez Miguel E. Vázquez-Méndez 《Environmental Modeling and Assessment》2017,22(4):279-289
In this work, we propose a technique to automatically optimize the monitoring of any distributed indicator (concentration of a substance along a river, blood pressure of a patient over time, etc.) for which a reliable estimate is previously available. From a mathematical point of view, the problem is based on obtaining a reliable estimate of the chosen indicator (e.g., by numerical simulation), and then solving a multi-objective optimization problem (with mixed real and integer variables) whose solution must provide an efficient and satisfactory monitoring strategy. As an illustrative case, we show the steps to follow in order to implement that strategy when designing a system for monitoring water quality in a river. Finally, we present and analyze the results when applying the proposed technique to study a real case in the Neuse River (North Carolina, USA). 相似文献
993.
Vibrio species isolated from four different sampling stations in the west coast of Peninsular Malaysia were screened for their antimicrobial resistance and plasmid profiles. A total of 138 isolates belonging to 15 different species were identified. Vibrio campbellii, V. parahaemolyticus, V. harveyi, and V. tubiashii were found to predominance species at all stations. High incidence of erythromycin, ampicillin, and mecillinam resistance was observed among the Vibrio isolates. In contrast, resistance against aztreonam, cefepime, streptomycin, sulfamethoxazole, and sulfonamides was low. All the Vibrio isolates in this study were found to be susceptible to imipenem, norfloxacin, ofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and oxytetracycline. Ninety-five percent of the Vibrio isolates were resistant to one or more different classes of antibiotic, and 20 different resistance antibiograms were identified. Thirty-two distinct plasmid profiles with molecular weight ranging from 2.2 to 24.8 kb were detected among the resistance isolates. This study showed that multidrug-resistant Vibrio spp. were common in the aquatic environments of west coast of Peninsular Malaysia. 相似文献
994.
995.
996.
Lasun T. Ogundele Oyediran K. Owoade Felix S. Olise Philip K. Hopke 《Environmental monitoring and assessment》2016,188(10):574
To identify the potential sources responsible for the particulate matter emission from secondary iron and steel smelting factory environment, PM2.5 and PM2.5?10 particles were collected using the low-volume air samplers twice a week for a year. The samples were analyzed for the elemental and black carbon content using x-ray fluorescence spectrometer and optical transmissometer, respectively. The average mass concentrations were 216.26, 151.68, and 138. 62 μg/m3 for PM2.5 and 331.36, 190.01, and 184.60 μg/m3 for PM2.5?10 for the production, outside M1 and outside M2 sites, respectively. The same size resolved data set were used as input for the positive matrix factorization (PMF), principal component factor analysis (PCFA), and Unmix (UNMIX) receptor modeling in order to identify the possible sources of particulate matter and their contribution. The PMF resolved four sources with their respective contributions were metal processing (33 %), e-waste (33 %), diesel emission (22 %) and soil (12 %) for PM2.5, and coking (50 %), soil (29 %), metal processing (16 %) and diesel combustion (5 %) for PM2.5?10. PCFA identified soil, metal processing, Pb source, and diesel combustion contributing 45, 41, 9, and 5 %, respectively to PM2.5 while metal processing, soil, coal combustion and open burning contributed 43, 38, 12, and 7 %, respectively to the PM2.5?10. Also, UNMIX identified metal processing, soil, and diesel emission with 43, 42 and 15 % contributions, respectively for the fine fraction, and metal processing (71 %), soil (21 %) and unidentified source (1 %) for the coarse fraction. The study concluded that metal processing and e-waste are the major sources contributing to the fine fraction while coking and soil contributed to the coarse fraction within the factory environment. The application of PMF, PCFA and UNMIX receptor models improved the source identification and apportionment of particulate matter drive in the study area. 相似文献
997.
998.
999.