全文获取类型
收费全文 | 17207篇 |
免费 | 188篇 |
国内免费 | 140篇 |
专业分类
安全科学 | 389篇 |
废物处理 | 699篇 |
环保管理 | 2166篇 |
综合类 | 3743篇 |
基础理论 | 4036篇 |
环境理论 | 9篇 |
污染及防治 | 4230篇 |
评价与监测 | 1108篇 |
社会与环境 | 1089篇 |
灾害及防治 | 66篇 |
出版年
2022年 | 133篇 |
2021年 | 152篇 |
2019年 | 129篇 |
2018年 | 234篇 |
2017年 | 236篇 |
2016年 | 362篇 |
2015年 | 283篇 |
2014年 | 408篇 |
2013年 | 1197篇 |
2012年 | 461篇 |
2011年 | 716篇 |
2010年 | 533篇 |
2009年 | 629篇 |
2008年 | 729篇 |
2007年 | 761篇 |
2006年 | 671篇 |
2005年 | 555篇 |
2004年 | 575篇 |
2003年 | 558篇 |
2002年 | 514篇 |
2001年 | 631篇 |
2000年 | 403篇 |
1999年 | 310篇 |
1998年 | 196篇 |
1997年 | 217篇 |
1996年 | 238篇 |
1995年 | 240篇 |
1994年 | 248篇 |
1993年 | 227篇 |
1992年 | 209篇 |
1991年 | 211篇 |
1990年 | 200篇 |
1989年 | 177篇 |
1988年 | 173篇 |
1987年 | 157篇 |
1986年 | 158篇 |
1985年 | 150篇 |
1984年 | 172篇 |
1983年 | 173篇 |
1982年 | 177篇 |
1981年 | 150篇 |
1980年 | 139篇 |
1979年 | 124篇 |
1978年 | 138篇 |
1977年 | 116篇 |
1976年 | 105篇 |
1975年 | 109篇 |
1974年 | 118篇 |
1971年 | 98篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
711.
712.
Przemysław Niedzielski Marek Siwulski Monika Gąsecka Lidia Kozak Iwona Rissmann 《Journal of environmental science and health. Part. B》2013,48(12):929-937
The aim of the study was to evaluate the possibility of supplementation with inorganic forms of selenium (Na2SeO4 and Na2SeO3) in concentrations of 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 and 1.5 mM of three medicinal mushroom species: Agrocybe aegerita, Hericium erinaceus and Ganoderma lucidum. Tested mushroom species grew in Se additions of 0–0.6 mM (A. aegerita and H. erinaceus), while growth of G. lucidum bodies was observed for 0–0.8 mM. For the latter mushroom species, the total Se content was the highest. Content of Seorg was diverse; for control bodies it was the highest for G. lucidum (only organic forms were present), lower for A. aegerita (84% organic forms) and the lowest for H. erinaceus (56% organic forms). Accumulation of Se(IV) was generally significantly higher than Se(VI) for all tested mushroom species. There was no significant decrease of A. aegerita or G. lucidum biomass with the exception of G. lucidum bodies growing under 0.8 mM of Se species addition (15.51 ± 6.53 g). Biomass of H. erinaceus bodies was the highest under 0.2 (197.04 ± 8.73 g), control (191.80 ± 6.06 g) and 0.1 mM (185.04 ± 8.73 g) of both inorganic salts. The addition to the medium of Se salts brought about macroscopic changes in the fruiting bodies of the examined mushrooms. Concentrations exceeding 0.4 mM caused diminution of carpophores or even their total absence. In addition, colour changes of fruiting bodies were also recorded. At Se concentrations of 0.4 and 0.6 mM, A. aegerita fruiting bodies were distinctly lighter and those of H. erinaceus changed colour from purely white to white-pink. 相似文献
713.
Donald R. Rowe William G. Lloyd 《Journal of the Air & Waste Management Association (1995)》2013,63(3):308-315
ABSTRACT Stable heterogeneous catalysts for the oxidative removal of CO from air at ambient temperatures have been developed. An alumina support impregnated with PdCl2, CuCl2, and CuSO4 is described. Optimal activity was obtained with Pd 0.020 mol/kg, Cu 0.50 mol/kg, CuCl2 20-30% of total Cu, a 2- to 24-hr soak, filtration of surplus raffinate, and a 2- to 4-hr firing in air at 200-350 °C. The catalysts are effective at 20-26 °C and relative humidities in the 15-90% range. They are reversibly deactivated by completely dry or water-saturated air streams. These catalysts have been tested at space velocities up to 30,000 hr-1. In contact with <100 ppm CO, they are highly efficient, removing ~99% of the CO with contact times of ~120 msec (pseudo-first order k' > 25 sec-1). At much higher CO concentrations, the maximum CO loading rate—limited by the Cu(I) reoxidation rate—is approximately 17 m mol CO per Limol Pd per hour. 相似文献
714.
Judith C. Chow John G. Watson Richard T. Egami Clifton A. Frazier Zhiqiang Lu Andrew Goodrich 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1134-1142
Street sweeping is often proposed as a means of reducing the emissions from paved roads. The objective of this study was to evaluate the effectiveness of street sweeping on ambient particulate matter concentrations and to determine the difference In source contributions to PM10 concentrations between street sweeping and non-street sweeping periods. Chemically-speciated measurements of PM10 and PM2.5 were taken in the commercial section of Reno, Nevada, for a one-month sampling period. The Chemical Mass Balance (CMB) model was applied to these data and an average of approximately 50 percent of the PM10 was apportioned to resuspended geological material. During half of the sampling period, streets In the vicinity of the sampling site were completely swept with a regenerative-air vacuum sweeper, while no sweeping was performed during the remainder of the experiment. Ratios of primary geological contributions divided by primary motor vehicle contributions to PM10 were compared between sweeping and non-sweeping periods using analysis of variance. This ratio of source contributions minimizes the effects of variations in traffic volume and meteorological dispersion. No significant differences in geological contributions to PM10 were detected as a result of regenerative-air vacuum street sweeping. 相似文献
715.
Ruthann A. Rudel Julia G. Brody John D. Spengler Jose Vallarino Paul W. Geno Gang Sun 《Journal of the Air & Waste Management Association (1995)》2013,63(4):499-513
ABSTRACT In order to characterize typical indoor exposures to chemicals of interest for research on breast cancer and other hormonally mediated health outcomes, methods were developed to analyze air and dust for target compounds that have been identified as animal mammary carcinogens or hormonally active agents and that are used in commercial or consumer products or building materials. These methods were applied to a small number of residential and commercial environments to begin to characterize the extent of exposure to these classes of compounds. Phenolic compounds, including nonylphenol, octylphenol, bisphenol A, and the methoxychlor metabolite 2,2-bis (p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), were extracted, derivatized, and analyzed by gas chromatography/mass spectrometry (GC/MS)–selective ion monitoring (SIM). Selected phthalates, pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were extracted and analyzed by GC/MS-SIM. Residential and workplace samples showed detectable levels of twelve pesticides in dust and seven in air samples. Phthalates were abundant in dust (0.3524 μg/g) and air (0.005-2.8 μg/m3). Nonylphenol and its mono- and di-ethoxylates were prevalent in dust (0.82-14 μg/g) along with estrogenic phenols such as bisphenol A and o-phenyl phenol. In this 7-sample pilot study, 33 of 86 target compounds were detected in dust, and 24 of 57 target compounds were detected in air. In a single sample from one home, 27 of the target compounds were detected in dust and 15 in air, providing an indication of chemical mixtures to which humans are typically exposed. 相似文献
716.
L.-W. Antony Chen Judith C. Chow Bruce G. Doddridge Russell R. Dickerson William F. Ryan Peter K. Mueller 《Journal of the Air & Waste Management Association (1995)》2013,63(8):946-956
Abstract Observations of the mass and chemical composition of particles less than 2.5 μm in aerodynamic diameter (PM2.5), light extinction, and meteorology in the urban Baltimore-Washington corridor during July 1999 and July 2000 are presented and analyzed to study summertime haze formation in the mid-Atlantic region. The mass fraction of ammoniated sulfate (SO4 2-) and carbonaceous material in PM2.5 were each ~50% for cleaner air (PM2.5 < 10 μg/m3) but changed to ~60% and ~20%, respectively, for more polluted air (PM2.5 > 30 μg/m3). This signifies the role of SO4 2- in haze formation. Comparisons of data from this study with the Interagency Monitoring of Protected Visual Environments network suggest that SO4 2? is more regional than carbonaceous material and originates in part from upwind source regions. The light extinction coefficient is well correlated to PM2.5 mass plus water associated with inorganic salt, leading to a mass extinction efficiency of 7.6 ± 1.7 m2/g for hydrated aerosol. The most serious haze episode occurring between July 15 and 19, 1999, was characterized by westerly transport and recirculation slowing removal of pollutants. At the peak of this episode, 1-hr PM2.5 concentration reached ~45 μg/m3, visual range dropped to ~5 km, and aerosol water likely contributed to ~40% of the light extinction coefficient. 相似文献
717.
Chuen-Jinn Tsai Kai-Chung Cheng Shankar G. Aggarwal Tung-Sheng Shih I.-Fu Hung 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1265-1272
Abstract A new triple filter system sampler/model is proposed for the precise and accurate simultaneous sampling and determination of gas- and aerosol-phase 2,4-toluene diisocyanate (TDI). The system consists of two front Teflon filters for sampling aerosol-phase TDI and a final coated glass fiber filter to collect gas-phase TDI. The aerosol-phase TDI is collected on the first Teflon filter, while the second Teflon filter is used to estimate gaseous TDI adsorbed by the first. According to the gas adsorption test of two Teflon filters in series, the TDI gas adsorption fraction of the two filters is almost the same. Results of the evaporation test using pure TDI aerosols collected on the Teflon filter show that significant evaporation of the compound does not occur during sampling. These two findings allow the use of a model to estimate accurate gasand aerosol-phase TDI concentrations. The comparison test with an annular denuder shows that the triple filter system can minimize the TDI sampling bias between the dual filter and the annular denuder systems. 相似文献
718.
719.
C. M. Peterson H. J. Paulus G. H. Foley 《Journal of the Air & Waste Management Association (1995)》2013,63(10):795-801
Instruments capable of measuring in situ numbers of particles within specific size ranges covering a particle-diameter spectrum of approximately 0.001 – 10 microns have been employed to continuously monitor the concentration and size-distribution of atmospheric aerosols. The monitoring site was a television tower located on the boundary between Minneapolis and St. Paul, Minnesota. Air samples were drawn from 70, 170, and 500 feet above ground level and analyzed with optical, electrical, and condensation particle counters to obtain a number-size distribution within the 0.001 – 10 micron size range. In addition to the measurement of particle number and size, several micrometeorological parameters were simultaneously monitored. Particle number-size distributions which were measured during periods of temperature inversion are reported 相似文献
720.
David G. McFarland Joseph W. DeNardo Walter G. Popiel 《Journal of the Air & Waste Management Association (1995)》2013,63(12):825-827
Verification of forecasts of COH levels at the Downtown Sampling Station using our objective forecast method developed in conjunction with the Allegheny County Bureau of Air Pollution Control gave excellent results. The next step was to expand the area of forecast coverage. COH data taken from July 1968 through June 1969 from six sampling stations located roughly in a large concentric arc around the Downtown Station were studied. Three of the stations are located in river valleys near large industrial plants and the other three are located on higher terrain in suburban areas. COH levels of Low, Moderate, High, and Very High (where Low = 0–0.9, Moderate = 1.0–1.9, High = 2.0–3.0, and Very High = >3.0) were used. The total number of occurrences of High and Very High COHS at the Downtown Station was 10.7% of the total data sample. This was more than twice the frequency of any of the outlying stations. An evaluation of the statistical frequencies indicate the Downtown Station can safely be used as a “control station” in forecasting Low or Moderate COH levels for the six surrounding stations. However, the occurrence of High or Very High COH levels at the six outlying stations do not occur with a high enough statistical consistency to be predicted by using the forecast value of the Downtown Station. The valley stations exhibit the characteristics of separate sub air basins particularly during a period in which morning inversions occur for two or more consecutive days and the average daily wind speed does not exceed 4 m/sec. The results show it is possible to forecast only Low or Moderate COH levels for each of the six outlying stations by using statistical correlations derived from the Downtown Station. Separate objective forecasts which relate the pollution buildup in each valley sub air basin must be used when High or Very High COHS are forecast at the Downtown Station. 相似文献