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71.
The investigation of cryogenic liquid pool spreading is an essential procedure to assess the hazard of cryogenic liquid usage. There is a wide range of models used to describe the spreading of a cryogenic liquid pool. Many of these models require the evaporation velocity, which has to be determined experimentally because the heat transfer process between the liquid pool and the surroundings is too complicated to be modeled. In this experimental study, to measure the evaporation velocity when the pool is spreading, liquid nitrogen was continuously released onto unconfined concrete ground. Almost all of the reported results are based on a non-spreading pool in which cryogenic liquid is instantaneously poured onto bounded ground for a very short period of time. For the precise measurement of pool spreading and evaporation weight with time, a cone-type funnel was designed to achieve a nearly constant liquid nitrogen release rate during discharge. Specifically, three nozzles with nominal flow rates of 3.4 × 10−2 kg/s, 5.6 × 10−2 kg/s and 9.0 × 10−2 kg/s were used to investigate the effect of the release rate on the evaporation velocity. It is noted that information about the release rate is not necessary to measure the evaporation velocity in case of the non-spreading pool. A simultaneous measurement of the pool location using thermocouples and of the pool mass using a digital balance was carried out to measure the evaporation velocity and the pool radius. A greater release flow rate was found to result in a greater average evaporation velocity, and the evaporation velocity decreased with the spreading time and the pool radius. 相似文献
72.
I.Y. Mostafa E.F. Shabana Z. Khalil F.I.Y. Mostafa 《Journal of environmental science and health. Part. B》2013,48(5-6):499-512
Abstract The growth and total carbohydrate contents of Nostoc muscorum and Tolypothrix tenuis were greatly and significantly reduced by the application of parathion. “Chlorophyll a”, carotene biosynthesis and the rate of glucose absorption were enhanced after supplementation of parathion to the culture media of both cyanobacteria. Nitrogen released to the media, total nitrogen content and total nitrogen fixed were increased in both organisms‐ Increase in protein content was accompanied by remarkable drop in amino, peptide and ammonia fractions‐ Phosphorus uptake, RNA, DNA and total phosphorus content were accelerated to reach maximum accumulation at the highest insecticide level. In metabolism study using 14C‐labelled compound, parathion was readily degraded by Nostoc and Tolypothrix. Following ten days incubation, the aqueous fractions contained 21.1% and 18.1% of the initial activity in Nostoc and Tolypothrix respectively. TLC analysis of the hydrolytic products revealed the presence of three metabolites: p‐aminophenol, p‐nitrophenol and aminoparathion. 相似文献
73.
Swimming pools are considered to be the prime source for public exposure to trihalomethanes (THMs), mainly chloroform, because of their use for hygienic purposes. High doses of chlorine are easily perceptible by smell. The aim of this study was to measure simultaneously the THM levels in urine and blood of swimmers and in pool water itself (from city and university swimming pool), in order to investigate further the relationship between substances in different matrices at known environmental levels with uptake of these substances in indoor swimming pools. Volatile analytes were isolated and preconcentrated from the samples by thin layer headspace analysis (TLHS) with autogenous generation of the liquid sorbent. Chloroform, bromodichloromethane and dibromochloromethane were detected in the urine of all persons attending a swimming pool. Concentrations of THM compounds varied in the case of each swimmer. The research confirmed that approximately 10% of the volatile haloorganic compounds are excreted in urine in the unchanged form. 相似文献
74.
We investigate whether positive framing increases cooperation in three social dilemmas with slightly different properties: a linear public goods (PG) game, a non-linear PG game, and a common pool resource (CPR) game. Results from our laboratory experiments show that contributions to a linear PG are higher if the externality is framed positively, rather than negatively, corroborating earlier findings by Andreoni (1995). By contrast, we find no such framing effects in the non-linear PG game or the CPR game. In these games, the best response in the material payoffs is to contribute less if others contribute more, counteracting effects of pro-social preferences. Positive framing therefore does not help to solve the tragedy of the commons. 相似文献
75.
Yuanyuan Qu Jiti Zhou E. Shen Qiao M Zhaojing Zhang Ziyan Liu Wenli Shen Jingwei Wang Duanxing Li Huijie Li 《环境科学学报(英文版)》2015,27(8):126-132
Indole, a typical nitrogen heterocyclic aromatic pollutant, is extensively spread in industrial wastewater. Microbial degradation has been proven to be a feasible approach to remove indole, whereas the microbial resources are fairly limited. A bacterial strain designated as SHE was isolated and found to be an efficient indole degrader. It was identified as Cupriavidus sp. according to 16S rRNA gene analysis. Strain SHE could utilize indole as the sole carbon source and almost completely degrade 100 mg/L of indole within 24 hr. It still harbored relatively high indole degradation capacity within pH 4–9 and temperature 25°C–35°C. Experiments also showed that some heavy metals such as Mn2 +, Pb2 + and Co2 + did not pose severe inhibition on indole degradation. Based on high performance liquid chromatography–mass spectrum analysis, isatin was identified as a minor intermediate during the process of indole biodegradation. A major yellow product with m/z 265.0605 (C15H8N2O3) was generated and accumulated, suggesting a novel indole conversion pathway existed. Genome analysis of strain SHE indicated that there existed a rich set of oxidoreductases, which might be the key reason for the efficient degradation of indole. The robust degradation ability of strain SHE makes it a promising candidate for the treatment of indole containing wastewater. 相似文献
76.
77.
Soil organic carbon decomposition and carbon pools in temperate and sub-tropical forests in China 总被引:2,自引:0,他引:2
Yang L Pan J Shao Y Chen JM Ju WM Shi X Yuan S 《Journal of environmental management》2007,85(3):690-695
Decomposition of soil organic carbon (SOC) is a critical component of the global carbon cycle, and accurate estimates of SOC decomposition are important for forest carbon modeling and ultimately for decision making relative to carbon sequestration and mitigation of global climate change. We determined the major pools of SOC in four sites representing major forest types in China: temperate forests at Changbai Mountain (CBM) and Qilian Mountain (QLM), and sub-tropical forests at Yujiang (YJ) and Liping (LP) counties. A 90-day laboratory incubation was conducted to measure CO(2) evolution from forest soils from each site, and data from the incubation study were fitted to a three-pool first-order model that separated mineralizable soil organic carbon into active (C(a)), slow (C(s)) and resistant (C(r)) carbon pools. Results indicate that: (1) the rate of SOC decomposition in the sub-tropical zone was faster than that in the temperature zone, (2) The C(a) pool comprised approximately 1-3% of SOC with an average mean residence time (MRT) of 219 days. The C(s) pool comprised approximately 25-65% with an average MRT of 78 yr. The C(r) pool accounted for approximately 35-80% of SOC, (3) The YJ site in the sub-tropical zone had the greatest C(a) pool and the lowest MRT, while the QLM in the temperature zone had the greatest MRT for both the C(a) and C(s) pools. The results suggest a higher capacity for long-term C sequestration as SOC in temperature forests than in sub-tropical forests. 相似文献
78.
Methods for determination of minimum pool levels in reservoirs that consider sport fishery values are being sought by managers.
We developed a technique for assessing the effects of incremental changes in minimum pool levels on potential salmonid abundance
in small (<100 surface hectares at full pool) reservoirs in Wyoming managed for irrigation and municipal water supplies. The
method has two components. One component is used to determine the minimum pool level needed to eliminate the risk of overwinter
loss of salmonids due to low dissolved oxygen concentrations. The other component predicts the potential biomass of salmonids
in reservoirs as a function of water depth and total dissolved solids concentration of the reservoir water. Application of
the method is demonstrated for two reservoirs in Wyoming.
The unit is jointly supported by the University of Wyoming, the Wyoming Game and Fish Department, and the US Fish and Wildlife
Service. 相似文献
79.
含氯化亚铁添加剂细水雾灭火有效性的实验研究 总被引:8,自引:2,他引:8
为了提高常规细水雾的灭火有效性,拓展其应用范围,本文采用小尺度实验的方法,研究了含氯化亚铁添加剂细水雾在不同燃料种类、添加剂浓度、压力下扑灭池火的有效性。实验结果表明:向细水雾中添加氯化亚铁,显著地影响了它的灭火性能;细水雾的灭火时间随着加入的氯化亚铁的质量浓度变化而发生改变,而且存在一个最短灭火时间浓度;细水雾喷头的工作压力和燃料的类型也对细水雾的灭火性能有影响,喷头工作压力越大,细水雾的平均灭火时间越短;在相同的实验条件下,细水雾灭煤油火的时间要短于灭乙醇火的时间。 相似文献
80.