全文获取类型
收费全文 | 1218篇 |
免费 | 161篇 |
国内免费 | 297篇 |
专业分类
安全科学 | 341篇 |
废物处理 | 21篇 |
环保管理 | 213篇 |
综合类 | 595篇 |
基础理论 | 148篇 |
污染及防治 | 140篇 |
评价与监测 | 72篇 |
社会与环境 | 57篇 |
灾害及防治 | 89篇 |
出版年
2024年 | 4篇 |
2023年 | 16篇 |
2022年 | 42篇 |
2021年 | 58篇 |
2020年 | 57篇 |
2019年 | 63篇 |
2018年 | 38篇 |
2017年 | 52篇 |
2016年 | 71篇 |
2015年 | 61篇 |
2014年 | 88篇 |
2013年 | 98篇 |
2012年 | 111篇 |
2011年 | 117篇 |
2010年 | 76篇 |
2009年 | 74篇 |
2008年 | 70篇 |
2007年 | 116篇 |
2006年 | 88篇 |
2005年 | 52篇 |
2004年 | 49篇 |
2003年 | 34篇 |
2002年 | 27篇 |
2001年 | 24篇 |
2000年 | 32篇 |
1999年 | 19篇 |
1998年 | 17篇 |
1997年 | 25篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 13篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1676条查询结果,搜索用时 406 毫秒
951.
B. H. King 《Behavioral ecology and sociobiology》2000,48(4):316-320
In the parasitoid wasp Spalangia endius more offspring and a greater proportion of daughters were oviposited in, and emerged from 0-day-old versus 3-day-old hosts.
Offspring that developed on the younger hosts (1) were larger at adulthood, (2) developed more quickly, (3) had higher survivorship
to adulthood, and (4) were more often able to chew their way out of the host. Sons and daughters did not differ in how host
age affected their size, development rate, or survivorship. The greater proportion of daughters from the younger hosts may
be adaptive, as described by the host quality model (a variant of the Trivers and Willard hypothesis). It is adaptive if greater
size or more rapid development has a more positive effect on a daughter’s than a son’s fitness and the positive effect is
large enough to compensate for sons being trapped disproportionately to daughters in the older hosts. Despite greater success
at drilling the younger hosts, mothers did not try to drill them sooner or more often. Having previously oviposited on the
older rather than the younger hosts had no detrimental effect on the mother’s subsequent longevity or offspring production.
Received: 8 March 2000 / Revised: 9 June 2000 / Accepted: 24 June 2000 相似文献
952.
四种竞争与环境可持续性 总被引:1,自引:1,他引:0
本文提出了人类生产与消费活动所造成的环境功能的数量竞争、质量竞争、空间竞争和时间竞争的概念,系统地阐述了各自的内涵及其相互关系。 相似文献
953.
Sunil Kumar Sharma 《International Journal of Green Energy》2016,13(14):1490-1500
This study forecasts day-ahead wind speed at 15 minute intervals at the site of a wind turbine located in Maharashtra, India. Wind speed exhibits non-stationarity, seasonality and time-varying volatility clustering. Univariate linear and non-linear time series techniques namely MSARIMA, MSARIMA-GARCH and MSARIMA-EGARCH have been employed for forecasting wind speed using data span ranging from 3 days to 15 days. Study suggests that mean absolute percentage error (MAPE) values first decrease with the increase in data span, reaches its minima and then start increasing. All models provide superior forecasting performances with 5 days data span. It is further evident that ARIMA-GARCH model generates lowest MAPE with 5 days data span. All these models provide superior forecasts with respect to current industry practices. This study establishes that employing various linear and non-linear time series techniques for forecasting day-ahead wind speed can benefit the industry in terms of better operational management of wind turbines and better integration of wind energy into the power system, which have huge financial implications for wind power generators in India. 相似文献
954.
采用臭氧氧化污泥减量法对畜禽养殖废水SBR中的剩余污泥进行处理。当臭氧反应时间控制在30min时,污泥的溶解比例在30%左右(以MLSS计)。上清液中一定量的SCOD溶出可为生物处理单元提供充足的碳源,同时在上清液中,TN、TP及水相重金属浓度增加有限,臭氧氧化后的污泥液回流污水处理系统后造成的N、P处理负荷较小,重金属对污泥微生物的活性抑制风险较低。若继续延长臭氧的反应时间,上清液SCOD、TN、TP以及重金属cu、Pb的释放速率明显增加,同时上清液的C/N降低,臭氧化后的污泥液回流反而不利于生物单元的脱氮处理。综合考虑TN、TP及水相重金属浓度增加的危害性,臭氧反应时间应控制在30min,臭氧实际投加量应为123.1mg O3/gSS。 相似文献
955.
Satoshi Saitoh Albrecht Melber Hiroshi Ohbayashi Satoshi Nakai Masakuni Matsuoka Masaaki Hosomi 《Journal of Material Cycles and Waste Management》2008,10(1):71-78
We discuss the use of the Schmidt graphical method to calculate the time required to heat a polychlorinated biphenyl (PCB)-contaminated
capacitor in the vacuum thermal recycling process to the processing temperature of 400°C, and we evaluate the results of the
heating time calculation by comparing the calculated values with the corresponding experimental values. The thermal conductivity
and specific heat of the insulating paper and the carbonized paper in the capacitor were unknown, so we determined their values
from experimental data obtained during the vacuum thermal recycling process. The capacitor element is a multilamination of
aluminum foil and insulating paper, so we used an equation for a multilayer plane wall to calculate the value of the thermal
conductivity. For the thermal conductivity and specific heat of the insulating paper impregnated with PCBs, we used values
calculated from the mass ratios and thermal conductivities and specific heats of the individual materials. In addition, the
physical properties vary according to the treatment because of the evaporation of PCBs and the carbonization of the insulating
paper, so we modified the values of the thermal conductivity, specific heat, and density at the boiling point of the PCB and
the carbonization point of the insulating paper before performing the calculations. Our calculated heating times were almost
the same as, or were above, the experimental values, so we concluded that our method can be used as a simple calculation of
the heating time. 相似文献
956.
Earthworms’ body works as a ‘biofilter’ and they have been found to remove the 5 days’ BOD (BOD5) by over 90%, COD by 80–90%, total dissolved solids (TDS) by 90–92%, and the total suspended solids (TSS) by 90–95% from
wastewater by the general mechanism of ‘ingestion’ and biodegradation of organic wastes, heavy metals, and solids from wastewater
and also by their ‘absorption’ through body walls. Earthworms increase the hydraulic conductivity and natural aeration by
granulating the clay particles. They also grind the silt and sand particles, increasing the total specific surface area, which
enhances the ability to ‘adsorb’ the organics and inorganic from the wastewater. Intensification of soil processes and aeration
by the earthworms enable the soil stabilization and filtration system to become effective and smaller in size. Suspended solids
are trapped on top of the vermifilter and processed by earthworms and fed to the soil microbes immobilized in the vermifilter.
There is no sludge formation in the process which requires additional expenditure on landfill disposal. This is also an odor-free
process and the resulting vermifiltered water is clean and disinfected enough to be reused for farm irrigation and in parks
and gardens
G. Bharambe—GU & Research Assistant (Under Rajiv K. Sinha), U. Chaudhari—GU (Worked on vermiculture project). 相似文献
957.
The photodegradation of persistent and bioaccumulative perftuorooctanoic acid (PFOA) in water by 185 nm vacuum ultraviolet (VUV) light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids (PFCAs), that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit. 相似文献
958.
Multi-indicator assessment of water environment in government
environmental auditing 总被引:1,自引:0,他引:1
This study focused on a multi-indicator assessment methodology for governmental environmental auditing of water protection programs. The environmental status of Wuli Lake in China was assessed using the global indicators (driver-status-response) developed by the Commission on Sustainable Development, and four additional indicators proposed by the author: water quality, pollution load, aquatic ecosystem status, and lake sediment deposition. Various hydrological, chemical, biological and environmental parameters were used to estimate the values of the indicators for assessment of environmental status of the lake based on time series data sets for twenty years. The indicators proposed can be customized to meeting the needs for particular assessment of water protection programs. This method can be used to evaluate the performance of national environmental protection programs and provide technical support for environmental auditors. 相似文献
959.
Alga-lysing bacteria have been paid much attention to in recent years. In this study, the alga-lysing strain P05 which was isolated from an immobilizing biosystem was immobilized by coke and elastic filler, forming two biological reactors. The removal efficiencies of algae, NH3-N and organic matter using the two reactors were studied. The results showed that strain P05 was an ideal algal-lysing bacteria strain because it was easy to be immobilized by coke and elastic filler which are of cheap, low biodegradability and the simple immobilization procedure. After 7 d filming, the biological film could be formed and the reactors were used to treat the eutrophic water. These two reactors were of stability and high effect with low cost and easy operation. The optimal hydraulic retention time (HRT) of each reactor was 4 h. The algae removal rates were 80.38% and 82.1% (in term of Chl-a) of coke reactor and filler reactor, respectively. And that of NH3-N were 52.3% and 52.7%. The removal rates of CODMn were 39.03% and 39.64%. The strain P05 was identified as Bacillus sp. by PCR amplification of the 16S rRNA gene, BLAST analysis, and comparison with sequences in the GenBank nucleotide database. 相似文献
960.
Response of soil fauna to simulated nitrogen deposition: A nursery experiment in subtropical China 总被引:2,自引:0,他引:2
XU Guo-liang MO Jiang-ming FU Sheng-lei PER Gundersen ZHOU Guo-yi XUE Jing-Hua 《环境科学学报(英文版)》2007,19(5):603-609
We studied the responses of soil fauna to a simulated nitrogen deposition in nursery experimental plots in Subtropical China. Dissolved NH4NO3 was applied to the soil by spraying twice per month for 16 months, starting January 2003 with treatments of 0, 5, 10, 15 and 30 gN/(m2·a). Soil fauna was sampled after 6, 9, 13 and 16 months of treatment in three soil depths (0-5 cm, 5-10 cm, 10-15 cm). Soil available N increased in correspondence with the increasing N treatment, whereas soil pH decreased. Bacterial and fungal densities were elevated by the N treatment. Soil fauna increased in the lower nitrogen treatments but decreased in the higher N treatments, which might indicate that there was a threshold around 10 gN/(m2·a) for the stimulating effects of N addition. The N effects were dependent on the soil depth and sampling time. The data also suggested that the effects of the different N treatments were related to the level of N saturation, especially the concentration of NO3- in the soil. 相似文献