全文获取类型
收费全文 | 40455篇 |
免费 | 400篇 |
国内免费 | 269篇 |
专业分类
安全科学 | 1163篇 |
废物处理 | 2277篇 |
环保管理 | 5441篇 |
综合类 | 5561篇 |
基础理论 | 10963篇 |
环境理论 | 11篇 |
污染及防治 | 9385篇 |
评价与监测 | 3169篇 |
社会与环境 | 2940篇 |
灾害及防治 | 214篇 |
出版年
2023年 | 154篇 |
2022年 | 277篇 |
2021年 | 345篇 |
2020年 | 214篇 |
2019年 | 267篇 |
2018年 | 1822篇 |
2017年 | 1752篇 |
2016年 | 1867篇 |
2015年 | 693篇 |
2014年 | 922篇 |
2013年 | 2660篇 |
2012年 | 1521篇 |
2011年 | 2650篇 |
2010年 | 1805篇 |
2009年 | 1756篇 |
2008年 | 2258篇 |
2007年 | 2512篇 |
2006年 | 1320篇 |
2005年 | 1171篇 |
2004年 | 1139篇 |
2003年 | 1135篇 |
2002年 | 1087篇 |
2001年 | 1156篇 |
2000年 | 831篇 |
1999年 | 521篇 |
1998年 | 404篇 |
1997年 | 413篇 |
1996年 | 422篇 |
1995年 | 490篇 |
1994年 | 424篇 |
1993年 | 371篇 |
1992年 | 394篇 |
1991年 | 376篇 |
1990年 | 338篇 |
1989年 | 332篇 |
1988年 | 309篇 |
1987年 | 261篇 |
1986年 | 258篇 |
1985年 | 267篇 |
1984年 | 289篇 |
1983年 | 278篇 |
1982年 | 284篇 |
1981年 | 243篇 |
1980年 | 176篇 |
1979年 | 190篇 |
1978年 | 167篇 |
1977年 | 141篇 |
1975年 | 141篇 |
1973年 | 169篇 |
1972年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Kazuharu Yoshizuka Syouhei Nishihama Hideki Sato 《Environmental geochemistry and health》2010,32(4):297-302
The objective of this study was to survey the cation and anion contents of geothermal waters to gather fundamental information
on geographical variations. Sixteen sites in hot spring areas on the island of Kyushu in Japan were studied. The study focused
on the arsenic content of the samples. Very high arsenic concentrations (more than 0.1 mg/l) were detected in most of the
geothermal waters sampled. High contents of boron and fluoride (more than 1.0 mg/l) were also detected in some samples. Arsenic
removal was performed on a laboratory scale using columns packed with a magnetite-type adsorbent. The reduction of arsenic
contamination to a concentration of less than 0.01 mg/l could be achieved in the early stages of adsorption (bed volume = 200). 相似文献
912.
913.
A. Mirmohseni M. Rastgouy Houjaghan 《Journal of environmental science and health. Part. B》2013,48(4):278-284
A simple and cost-effective analysis method based on quartz crystal nanobalance (QCN) coated with a molecularly imprinted polymer (MIP) for measurement of methomyl was investigated. In the first part of this study, a sensitive, selective and reliable quartz crystal nanobalance (QCN) sensor was designed for the selective determination of methomyl in aqueous solutions. In the second part, in order to demonstrate the applicability and performance of the fabricated sensor in the real world situation, it was successfully applied for the determination of methomyl residual in photo catalytic degradation by ZnO powders in aqueous solutions. The fabricated sensor presents a high selectivity and sensitivity (4.56 Hz per mg L?1) for methomyl and it can be used for determination of methomyl concentration ranged between 1 to 45 mg L?1. Furthermore, good reproducibility, R.S.D. = 2.14% (n = 5) was observed. To investigate the performance of the sensor, the change in the insecticide concentration during the photocatalytic degradation of methomyl by ZnO was investigated by QCN and UV/Vis spectroscopy. Results obtained from QCN sensor and UV/Vis spectroscopy measurement are in good mutual agreement. So the fabricated sensor may provide an efficient, low cost, easy-to-use method for the in-field evaluation of specific targeted analytes in aqueous solutions which in turn may lead to improved food and water safety. 相似文献
914.
915.
A. P. Altshuller S. L. Kopczynski D. Wilson W. Lonneman F. D. Sutterfield 《Journal of the Air & Waste Management Association (1995)》2013,63(10):791-794
Effects associated with photochemical air pollution were measured during irradiation of n-butane-nitrogen oxide or n-butane-ethane-nitrogen oxide mixtures, with small amounts of propylene or toluene added. The effects measured including nitrogen dioxide and oxidant dosages, yields of formaldehyde and peroxy-acetyl nitrate, and eye irritation response. The results obtained clearly show that beneficial effects result from selective changes in hydrocarbon composition as well as from reduction of total hydrocarbon concenfration. Exclusion of olefins and alkylbenzenes was highly effective in reducing oxidant dosage, formaldehyde and peroxyacetyl nitrate concentrations, and eye irritation response. The only penalty was a modest increase in nitrogen dioxide dosage. A large reduction in nitrogen oxide concentration reduced nitrogen dioxide dosage and eye irritation response, but with the penalty of a large increase in oxidant dosage. The desirability of preferentially reducing olefins and alkylbenzenes rather than paraffinic hydrocarbons, acetylene, and benzene is strongly supported by this study. Research and development efforts should be directed toward preferential hydrocarbon control by mechanical or catalytic control 相似文献
916.
Cindy DeForest Hauser Paul Battle Nina Mace 《Atmospheric environment (Oxford, England : 1994)》2009,43(10):1823-1826
Passive sampling devices are popular in applications which do not require the monitoring of hourly concentrations. Nitrogen oxides are often collected using filters coated with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). The filter extract can then be analyzed using flow injection analysis ion chromatography fitted with a copper/cadmium reduction column or UV–vis spectroscopy. When the latter is used to measure low concentrations of nitrogen oxides, absorbance by PTIO at the analytical wavelength of 545 nm contributes significantly. PTIO concentration on the filter also shows variation with filter storage and exposure time not accounted for in a single point blank subtraction at the analytical wavelength. A method is presented that uses a scaling factor to account for variations in concentration of PTIO on the field blank and provides a more accurate method for determining and correcting for the PTIO contribution to absorption when measuring ambient nitrogen oxide concentrations. 相似文献
917.
918.
Vincent A. Dutkiewicz Sofia Alvi Badar M. Ghauri M. Iqbal Choudhary Liaquat Husain 《Atmospheric environment (Oxford, England : 1994)》2009,43(10):1737-1744
We report data from a yearlong (2006–2007) study of black carbon concentrations ([BC]) measured at 5-min intervals with an Aethalometer in Karachi, Pakistan. Daily mean [BC] varied from about 1 to 15 μg m?3. However, short-term spikes exceeding 40 μg m?3 were common, occurring primarily during the morning and evening rush-hour periods. The [BC] values were highest during November through February, ~10 μg m?3, and lowest during June through September, ~2 μg m?3. Diurnal, seasonal, and day-of-the-week trends are discussed. It is demonstrated that these trends are strongly affected by meteorological patterns. A simple expression is applied to the concentration profiles to separate the effects of meteorological conditions and elucidate the underlying emissions patterns. Daily emissions varied from 14,000 to 22,000 kg of BC per day. When integrated over the year emissions for Karachi Proper were estimated at 6.7 kilometric tons per year and emissions for greater Karachi were 17.5 kilometric tons per year. Folding in the populations of each area yields BC emissions of 0.74 and 1.1 kg per person per year, respectively. Applying the model to previously collected data at Lahore, Pakistan yields emissions during November–January that are around a factor of two higher than those in Karachi, but because the BC measurements in Lahore covered only three months, no estimates of annual emissions were attempted. Given the large populations of these cities the local health impact from PM alone is expected to be severe but because of the high [BC] emissions the impact on the global climate may be equally significant. 相似文献
919.
920.