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261.
262.
上流式曝气生物滤池两种填料启动挂膜的试验研究 总被引:3,自引:2,他引:1
在相同运行条件下,对瓷粒和陶粒2种不同填料曝气生物滤池(BAF)的启动运行进行了实验研究,考察了不同填料在挂膜过程中CODCr和NH4^+-N的去除效果及出水NO2^--N和NO3^--N质量浓度的变化。结果表明,在常温下(20~25℃)2种填料的所需的启动时间差异较大,陶粒填料所需时间为17d,而瓷粒填料别需37d。启动挂膜过程中,两者对CODCr和NH4^+-N可达到基本相同的去除率,但所需运行时间差异较大,陶粒BAF较之瓷粒BAF稳定,且硝化效果好于瓷粒BAF. 相似文献
263.
松花江哈尔滨江段水生生物调查与评价 总被引:1,自引:0,他引:1
本文分别应用着生藻类、着生原生动物和底栖动物对松花江哈尔滨江段的水质状况进行监测,然后进行综合的生物学评价。结果表明松花江哈尔滨江段的水质受到污染,污染等级为3级。 相似文献
264.
Insect immunology is an active research arena, however, the vast majority of research in the area is conducted on model species
taken from laboratory cultures. We tested the hypothesis that insects are regularly exposed to infections or invasions in
nature and here report results of a field study designed to assess the extent of natural infections in insects collected from
agrarian fields surrounding Kahramanmaraş, Turkey. Specimens were dissected to assess numbers of nodules. Formation of darkened,
melanotic nodules is the predominant cellular immune reaction to microbial and parasitic infection, and once formed, the nodules
are permanently attached to internal surfaces. The collected insects were healthy. Of the >400 examined specimens, at least
some nodules were found in 98%. Numbers of nodules ranged from ∼2/individual to >100 nodules/individual. We conclude that
insects are regularly challenged by microbial and parasitic infections from which they recover. The novel implication of our
data is that insect immune systems may limit the host range and effectiveness of agents deployed in biological control programs.
Knowledge of insect immune systems may contribute to increased use of biopesticides globally. 相似文献
265.
对升流式二级曝气生物滤池去除COD和NHs—N的效果进行了试验研究,并在各个阶段对比中找出最优的运行工况,从而达到节约能源,降低运行成本的目的。通过试验对水力负荷、有机负荷、气水比等参数的变化对去除COD和NH3-N效果的影响。研究结果表明,在进水水力负荷为1~4m3/m^2·h、有机负荷为4-13kgCOD/ms·d及气水比1:1~3:1的工艺条件下,COD和NH3-N的出水水质均能满足杂用水需要。 相似文献
266.
Purpose: Fatal pedestrian collisions are over-represented at night and poor conspicuity is believed to be a leading causative factor. Retro-reflective clothing enhances pedestrian conspicuity, particularly when placed in a biological motion or “biomotion” configuration. In this study, we explored how various retro-reflective clothing configurations affected the ability to judge the direction of a pedestrian walking across the road, which has important implications for collision avoidance. Methods: Participants included 21 young drivers (mean age 21.6 ± 2.0 years) with normal vision. A closed-road circuit was used to assess the accuracy of drivers’ judgement of the direction of walking of a pedestrian at night-time wearing one of five different clothing configurations: four with retro-reflective materials placed in different locations (Biomotion, Legs + Torso, Torso Only, Legs Only), and a control wearing only black clothing (Street). Participants were seated in a stationary vehicle with low beam headlamps, 135 m from a pedestrian, who walked across the road from both sides, in different directions (towards the car, straight across the road, or away from the car). Outcome measures included drivers’ response accuracy and confidence ratings for judging pedestrian walking direction. Results: Accuracy in judging pedestrian walking direction differed significantly across the clothing configurations (p < 0.001). Response accuracy was significantly higher for the Biomotion configuration (80% correct), compared to the other retro-reflective (Legs + Torso 64%; Torso Only 53%; Legs Only 50%) and Street configurations (33%). Similar trends were noted for confidence ratings across the clothing conditions, yet the relationship between confidence ratings and response accuracy within each clothing configurations was poor. Conclusions: The use of retro-reflective clothing in a biomotion configuration facilitated the highest accuracy and confidence in drivers’ judgment of pedestrian walking direction, compared to other configurations. These findings highlight the importance of using biomotion clothing for pedestrians at night, to not only facilitate drivers’ earlier recognition of pedestrians, but also increase their accuracy in determining the walking direction of pedestrians as they cross the road. Practical applications: The use of clothing incorporating retro-reflective material in a biomotion configuration for pedestrians crossing roads at night provides enhanced cues for drivers regarding the presence and walking direction of pedestrians. 相似文献
267.
Animals make use of the Earth’s magnetic field for navigation and regulation of vegetative functions; however, the anatomical
and physiological basis for the magnetic sense has not been elucidated yet. Our recent results from histology and X-ray analyses
support the hypothesis that delicate iron-containing structures in the skin of the upper beak of homing pigeons might serve
as a biological magnetometer. Histology has revealed various iron sites within dendrites of the trigeminal nerve, their arrangement
along strands of axons, the existence of three dendritic fields in each side of the beak with specific 3D-orientations, and
the bilateral symmetry of the whole system. Element mapping by micro-synchrotron X-ray fluorescence analysis has shown the
distribution of iron and its quantities. Micro-synchrotron X-ray absorption near-edge-structure spectroscopy has allowed us
to unambiguously identify maghemite as the predominating iron mineral (90 vs 10% magnetite). In this paper, we show that iron-based
magnetoreception needs the presence of both of these iron minerals, their specific dimensions, shapes, and arrangements in
three different subcellular compartments. We suggest that an inherent magnetic enhancement process via an iron-crusted vesicle
and the attached chains of iron platelets might be sufficient to account for the sensitivity and specificity required by such
a magnetoreceptor. The appropriate alignment between the Earth’s magnetic field and the maghemite bands would induce a multiple
attraction of the magnetite bullets perpendicular to the membrane, thus, triggering strain-sensitive membrane channels and
a primary receptor potential. Due to its 3D architecture and physicochemical nature, the dendritic system should be able to
separately sense the three vector components of the Earth’s local field, simultaneously—allowing birds to detect their geographic
position by the magnetic vector, i.e., amplitude and direction of the local magnetic field, irrespective of the animal’s posture
or movement and photoreception. 相似文献
268.
Set-aside management: How do succession, sowing patterns and landscape context affect biodiversity? 总被引:1,自引:0,他引:1
Teja Tscharntke Péter BatáryCarsten F. Dormann 《Agriculture, ecosystems & environment》2011,143(1):37-44
European Union (EU) member states set aside between 5 and 15% of arable land during the last two decades, but abolition of the set-aside scheme in 2008 caused a sudden loss in habitat availability and biodiversity in agricultural landscapes. Management of set-aside has many facets and in this perspective paper we focus on the biodiversity effects of successional age, sowing strategies and landscape context. Young, 1-2-year-old set-asides have been initially considered to be too ephemeral to have any conservation value. However, when a rich seed and bud bank is available, a species-rich natural (secondary) succession can be observed. Arable (annual) weed communities in the first two years of succession can even include endangered plant species with associated rare insect consumers. Furthermore, many bird species benefit from early-successional habitats, whereas small mammal communities are richer in older habitats. If the local plant species pool is poor, sowings of diverse mixtures from regional seed collections can be recommended. Set-aside managers using species-rich sowings often experience that dominant weeds suppress the less competitive annual species. This trend to species-poor communities can be avoided by intraspecific aggregation of competitively weak species. Broadening the spatial scale from the plot to the landscape, efficiency of set-aside is highest in simple landscapes, where set-aside exhibits greatest effect in enhancement of biodiversity and associated services such as pollination and biological control. In complex landscapes, however, additional set-aside does not add much to the high level of biodiversity and ecological processes already present. Twenty percent of semi-natural, non-crop habitat appears to be a rough threshold for enhancing biodiversity and sustaining services such as pollination and biological control, but improved set-aside management should have the potential to reduce the percentage of semi-natural non-crop habitat needed. EU policy should tailor set-aside schemes for the maintenance of biodiversity and also consider that management efficiency is higher in simple than complex landscapes. 相似文献
269.
270.
采用新型酶促厌氧填料、半软性填料、酶促好氧填料和PYC挂膜陶粒填料对两段错向流曝气生物滤池反应器进行污水处理试验研究,分析了4种填料对反应器污水处理效能的贡献并为反应器填料的选择提供科学依据.结果表明,以半软性填料和酶促好氧填料为组合填料的两段错向流曝气生物滤池反应器污水处理效能均优于其它填料. 相似文献