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591.
The Central Valley, California, R-EMAP project assessed the effects of highly modified, agriculturally dominated landuse on the aquatic resources of the lower portion of the Central Valley watersheds. The focus of this paper is to assess the utility of the EMAP design and the River Reach File version 3 (RF3) 1:100,000 scale Digital Line Graph (DLG) as a sampling frame. The study area is 34,099 mi2(88,316 km2) and comprises the lower reaches of the Sacramento River and San Joaquin River watersheds to the 1000 ft. (305 m) elevation. Sampling sites are selected using a tessellation stratified design to represent the two main populations of interest: natural streams and man-made waterways. Sites are selected to represent 13,226 miles of streams and sloughs, and 14,648 miles of irrigation canals, ditches and drains. To achieve an approximately equal sample size across stream orders and basins, the sample design was weighted by Strahler order categories to ensure sampling occurred in the higher order streams. Based on office and field reconnaissance, the study provided information on the quality of RF3 as a sampling frame. Site selection using RF3 had a success rate of approximately 44%. The RF3 database has an error rate of approximately 7%. When human influence factors were included, the error rate increased to 16%. There was an 11% error rate when selecting sites for natural streams, and approximately a 14% error rate for man-made waterways. The reconnaissance information indicated that presence or absence of irrigation ditches and return drains depends on changing agricultural uses. Some of the error in the RF3 for natural streams and man-made waterways can be attributed to rapid urban expansion, especially in the San Joaquin basin.  相似文献   
592.
In order to assess the urban runoff control effectiveness of a low-impact development best management practice (LID-BMP) treatment train system, a field test of selected LID-BMPs was conducted in China. The LID-BMPs selected include three grassed swales, a buffer strip, a bioretention cell, two infiltration pits, and a constructed wetland. The test site is in a campus in southern China. The LID-BMPs, connected in a series, received stormwater runoff from four tennis courts with an area of 2808 m2 and eight basketball courts with an area of 4864 m2. Construction of the LID-BMPs was completed in early spring of 2012, and the sampling was conducted during May of 2012 to September of 2013. During the sampling effort, besides the performance evaluations of grassed swales and the bioretention cell in controlling runoff quantity as well as quality, the emphasis was also on determining the performance of the LID-BMP treatment train system. A total of 19 storm events were monitored, with nine producing no runoff and ten producing runoff. Data collected from the ten storm events were analyzed for estimating runoff quantity (peak flow rate and total runoff volume) and quality reduction by the LID-BMPs. The sum of loads (SOL) method was used for calculating the water quality performance of LID-BMPs. Results indicated that, for peak flow rate, a bioretention cell reduction of 50–84 % was obtained, and grassed swale reduction was 17–79 %, with a runoff volume reduction of 47–80 and 9–74 %, respectively. For water quality, the bioretention cell in general showed good removal for zinc (nearly 100 %), copper (69 %), NH3-N (ammonia nitrogen) (51 %), and total nitrogen (TN) (49 %); fair removal for chemical oxygen demand (COD) (18 %); and poor removal for total suspended solids (TSS) (?11 %) and total phosphorus (TP) (?21 %). And its performance effectiveness for pollutant removal increased in the second year after 1 year of stabilizing. When considering the aggregated effect of the LID-BMP treatment train system, it showed excellent removal for NH3-N (73 %), TN (74 %), and TP (95 %) and fair removal for COD (19 %) and TSS (35 %). The assessment results of the LID-BMP treatment train system provide valuable information on how to link the different types of LID-BMP facilities and maximize the integrated effectiveness on urban runoff control.  相似文献   
593.
Polybrominated diphenyl ethers (PBDEs) are persistent, bioaccumulative, and toxic chemicals that are present in air, water, soil, sediment, and biota (including fish). Most previous studies of PBDEs in fish were spatially focused on targeted waterbodies. National estimates were developed for PBDEs in fish from lakes and reservoirs of the conterminous US (excluding the Laurentian Great Lakes) using an unequal probability design. Predator (fillet) and bottom-dweller (whole-body) composites were collected during 2003 from 166 lakes selected randomly from the target population of 147,343 lakes. Both composite types comprised nationally representative samples that were extrapolated to the sampled population of 76,559 and 46,190 lakes for predators and bottom dwellers, respectively. Fish were analyzed for 34 individual PBDE congeners and six co-eluting congener pairs representing a total of 46 PBDEs. All samples contained detectable levels of PBDEs, and BDE-47 predominated. The maximum aggregated sums of congeners ranged from 38.3 ng/g (predators) to 125 ng/g (bottom dwellers). Maximum concentrations in fish from this national probabilistic study exceeded those reported from recent targeted studies of US inland lakes, but were lower than those from Great Lakes studies. The probabilistic design allowed the development of cumulative distribution functions to quantify PBDE concentrations versus the cumulative number of US lakes from the sampled population.  相似文献   
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596.
Media plays a vital role in informing the public about environmental threats. Although climate change is a global problem, developing countries such as India are often more vulnerable to the impacts due to poverty, illiteracy, and low public awareness. Using data from a nationally representative survey in India, this paper explores the relationships between media use, issue attention, and trust in informational sources on one hand and science-based climate change beliefs, risk perceptions, and policy support on the other. Results suggest that the Indian media, through consistent and accurate coverage of global warming using trusted sources, can play a positive role in increasing public engagement among a largely unaware population. Implications for climate change communication in India are discussed.  相似文献   
597.
A lack of trust in the information exchanged via social media may significantly hinder decisionmaking by community members and emergency services during disasters. The need for timely information at such times, though, challenges traditional ways of establishing trust. This paper, building on a multi‐year research project that combined social media data analysis and participant observation within an emergency management organisation and in‐depth engagement with stakeholders across the sector, pinpoints and examines assumptions governing trust and trusting relationships in social media disaster management. It assesses three models for using social media in disaster management—information gathering, quasi‐journalistic verification, and crowdsourcing—in relation to the guardianship of trust to highlight the verification process for content and source and to identify the role of power and responsibilities. The conclusions contain important implications for emergency management organisations seeking to enhance their mechanisms for incorporating user‐generated information from social media sources in their disaster response efforts.  相似文献   
598.
Introduced plants that have both production values and negative impacts can be contentious. Generally they are either treated as weeds and their use prohibited; or unfettered exploitation is permitted and land managers must individually contend with any negative effects. Buffel grass (Cenchrus ciliaris) is contentious in Australia and there has been no attempt to broadly and systematically address the issues surrounding it. However, recent research indicates that there is some mutual acceptance by proponents and opponents of each others’ perspectives and we contend that this provides the basis for a national approach. It would require thorough and on-going consultation with stakeholders and development of realistic goals that are applicable across a range of scales and responsive to regional differences in costs, benefits and socio-economic and biophysical circumstances. It would be necessary to clearly allocate responsibilities and ascertain the most appropriate balance between legislative and non-legislative mechanisms. A national approach could involve avoiding the introduction of additional genetic material, countering proliferation in regions where the species is sparse, preventing incursion into conservation reserves where it is absent, containing strategically located populations and managing communities to prevent or reduce dominance by buffel grass. This approach could be applied to other contentious plant species.  相似文献   
599.
Membrane bioreactor treatment of commonly used organophosphate pesticides   总被引:1,自引:0,他引:1  
Five pesticide formulations registered for use in Canada containing organophosphate-insecticide active ingredients azinphos-methyl, chlorpyrifos, diazinon, malathion and phorate were subjected to treatment by membrane bioreactor (MBR) technology. The target active ingredients were introduced to the MBR at ppm level concentrations. The biodegradation of these compounds was analyzed daily using selected ion monitoring gas chromatography-mass spectrometry (GC/MS-SIM) following extraction of the analytes using solid-phase extraction (SPE). Amounts measuring 83 % to 98 % of the target analytes were removed with steady-state concentrations being reached within 5 days of their introduction. The dissolved oxygen, temperature, pH, and total heterotrophic bacterial population were monitored daily to ensure optimal conditions for biodegradation. The quality of the effluent from the MBR was assessed daily through spectrophotometric methods. Measurements were conducted for the concentration of ammonia, nitrate, nitrite, total and reactive phosphorus, as well as the chemical oxygen demand (COD) of the effluent. This study demonstrated that the MBR technology is feasible and efficient for treatment of organophosphate pesticides without introducing additional chemical additives.  相似文献   
600.
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