全文获取类型
收费全文 | 830篇 |
免费 | 53篇 |
国内免费 | 118篇 |
专业分类
安全科学 | 55篇 |
废物处理 | 16篇 |
环保管理 | 110篇 |
综合类 | 506篇 |
基础理论 | 96篇 |
污染及防治 | 164篇 |
评价与监测 | 31篇 |
社会与环境 | 10篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 12篇 |
2022年 | 16篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 26篇 |
2015年 | 24篇 |
2014年 | 26篇 |
2013年 | 36篇 |
2012年 | 37篇 |
2011年 | 63篇 |
2010年 | 29篇 |
2009年 | 56篇 |
2008年 | 39篇 |
2007年 | 72篇 |
2006年 | 63篇 |
2005年 | 51篇 |
2004年 | 41篇 |
2003年 | 45篇 |
2002年 | 43篇 |
2001年 | 38篇 |
2000年 | 41篇 |
1999年 | 43篇 |
1998年 | 29篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
排序方式: 共有1001条查询结果,搜索用时 296 毫秒
361.
A laboratory continuous feed biofilm reactor, comprising a bulk fluid reactor, a biofilm plastic module, a feed tank, and pneumatic devices and controls, was operated for a total period of 257 days, including seeding time, to treat domestic-strength synthetic wastewater under increasing ammonium nitrogen (NH(4)(+)--N) loading rates, ranging from 0.17+/-0.01 (0.71+/-0.06 gm(-2)d(-1)) to 0.70+/-0.02 kgm(-3)d(-1) (2.9+/-0.1 gm(-2)d(-1)). The biofilm plastic module was moved vertically in and out of the wastewater in continuous cycles. The maximum NH(4)(+)-N removal rate was reached during the maximum loading phase, when a NH(4)(+)--N loading rate of 0.70+/-0.02 kgm(-3)d(-1) (2.9+/-0.1 gm(-2)d(-1)) was applied to the system. During this loading period, the average NH(4)(+)--N removal rate was 0.30+/-0.10 kgm(-3)d(-1) (1.30+/-0.40 gm(-2)d(-1)). 相似文献
362.
363.
The ability of simultaneous biological phosphorus and nitrogen removal was investigated in a lab-scale continuous-flow two-sludge system. Alternating anaerobic and anoxic conditions were combined with contact oxidation stage for treating raw municipal wastewater. Long-term experiments showed that the contradiction of competing for the organic substrate between denitrifying bacteria and PAOs (phosphorus accumulating organisms) in traditional phosphorus and nitrogen removal system has been resolved. The system can adapt to low influent COD/TN ratio (C/N). Furthermore the SRT (sludge retention time) of nitrifying sludge and denitrifying phosphorus removal sludge can be controlled at optimal conditions respectively. The removal efficiency of COD, TP, TN, and NH4-N was 81.78%, 92.51%, 75.75%, and 84.47% respectively. It was also found that the appropriate influent C/N should be controlled at the range of 3.8-6, while the optimal C/N to the system ranged between 4-5, and the BFR (bypass sludge flow rate) should be controlled at 0.35 around. 相似文献
364.
Municipal Solid Waste (MSW) management in China has been transitioning from a mixed collection and treatment system to a separated collection and treatment system. The continuous rise of MSW treatment capacity and the optimization of technology structure provided basic facility support for China to promote MSW separation at source. China preferred a four-type separation system. Regulated recycling should be enhanced to improve the efficiency and sustainability of recycling industry. As food waste is the main composition of MSW in China, 20%–30% of the food waste diversion and land application could maximize the comprehensive environmental performance. Incineration is to be the pillar technology in MSW separated treatment system in China. 相似文献
365.
原位修复是一种可靠、卓有成效的河道水体净化修复技术,具有治理费用低和最大程度降解污染的特点,适合于污染严重、流量较小的河流水体。本文概述了河道曝气法、生物接触氧化、河流湿地处理和生态浮床等河道原位处理技术的原理、发展及应用情况,其中河道曝气和生物接触氧化起步早,技术较为成熟,为早期污染水体治理贡献很大,相对河流湿地处理和人工浮床起步晚,但成本低,耗资少,处理效率又高,具有很大的发展空间。这些工艺都是经济、有效以及符合可持续发展要求的生物生态技术,在国内外发展比较迅速,但在进一步改进的前提下,其应用前景将十分广阔。 相似文献
366.
367.
Increasing environmental concerns and the introduction of technologies based on renewable resources have stimulated the replacement of persistent petroleum-derived plastics with biodegradable plastics from biopolymers. As a consequence, a variety of products are currently manufactured from bioplastic, including carrier bags. This series of studies investigated the deterioration of carrier bags made with Mater-Bi (MB), a starch-based bioplastic, in soil, compost and two aquatic ecosystems, a littoral marsh and seawater. Results from the laboratory study indicated that bioplastic carrier bags were rapidly deteriorated in soil and compost. After three months of incubation, weight loss of specimens was of 37% and 43% in soil and compost, respectively. Conversely, little deterioration was observed in specimens buried in soil under field conditions or exposed to water of a littoral marsh and of the Adriatic Sea. These findings were consistent with the greater number of bacteria and especially fungi capable of degrading MB that were recovered from soil and compost with respect to the two aquatic ecosystems. Considering that a variety of microbial isolates are capable of using MB as a source of carbon, a new alternative to recycle these MB-based carrier bags was explored. More specifically, starchy residues from bags were fermented by the fungus Rhizopus oryzae to produce up to 35 mg of lactic acid per g of bag residues. 相似文献
368.
Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between 234Th and its parent 238U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, 210Po and 210Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the 210Po/210Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired 234Th/238U and 210Po/210Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated 210Po and 234Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both 210Po and 234Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump. 相似文献
369.
370.
静电放电测试是很多产品标准中常见的电磁兼容检测项目,本文叙述了静电放电测试中一些容易被测试人员忽视的细节,同时分析影响静电放电测试结果的因素,为EMC实验室和企业人员正确开展静电放电测试,和加强实验室管理提供帮助。 相似文献