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141.
矿难救生球系统在瓦斯爆炸冲击波作用下的动态响应 总被引:2,自引:0,他引:2
介绍矿难救生球系统(简称球)的原理及结构,构建巷道空间和球的分析模型,运用数值分析的方法,分别选择3种球体材料和3种球体厚度进行计算,对该系统在瓦斯爆炸冲击波作用下的动态响应进行研讨,分析冲击波作用下球表面的变形、等效应力、等效塑性应变以及球体材料、厚度等因素对球动态响应的影响。结果表明:运用数值分析的方法,可以为救生球系统设计建立一个仿真的实验环境,为优化系统设计、提高设计效率提供参考数据。 相似文献
142.
从电焊机保护接地(或接零)的规则、电源线与焊钳的安全技术、控制电器的安全技术、电焊工作业中的安全保障措施等四个方面,探讨了电弧焊作业中如何防范触电事故的技术措施,实践证明,所述的安全要求和技术方法对于电弧焊作业的安全管理和安全生产具有很高的实用价值。 相似文献
143.
Alexander V. Fedorov Alexey V. Shulgin 《Journal of Loss Prevention in the Process Industries》2007,20(4-6):317-321
The distributed mathematical model of magnesium particle ignition is developed taking into account the heterogeneous chemical reaction and the domain of particle thermal influence on gas. The problem solvability in the stationary case has allowed one to expand classification of regular modes of heating as well as the modes of extinction and ignition of a particle. The limiting size of a gas layer near a particle is found that determines an ignition mode. It is shown that the ignition delay time grows if we take into account the gas layer near the particle. Stability of some heating modes within the framework of finite and infinitesimal perturbations is studied. An opportunity to control the ignition process by high-frequency thermal action on the unstable particle gas states is shown. 相似文献
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146.
In many cooperatively breeding species, dominant females suppress reproduction in subordinates. Although it is commonly assumed
that aggression from dominant females plays a role in reproductive suppression, little is known about the distribution of
aggressive interactions. Here, we investigate the distribution of aggressive and submissive interactions among female meerkats
(Suricata suricatta). In this species, dominant females produce more than 80% of the litters, but older subordinates occasionally breed. Dominant
females commonly kill the pups of subordinates and usually evict older female subordinates from the group 1–3 weeks before
the birth of the dominant female's litter. The aggression frequency of the dominant female toward subordinates and the submission
frequency that each subordinate female showed to the dominant female increased as the age of the subordinate female increased
and as the birth of the dominant female's pups approached. Moreover, as birth approached, both of these behaviors intensified
more quickly between the dominant female and older subordinates than between the dominant female and younger subordinates.
The aggression frequency of the dominant female toward each subordinate female predicted whether that subordinate female was
evicted from the group; the submission frequency by each subordinate female predicted the timing of their eviction during
the pregnancy period of the dominant female. These results support the idea that conflict between dominant and subordinate
females increases with the age of subordinates and, since older subordinate females are most likely to reproduce, suggest
that dominant females may less easily control reproductive attempts by older subordinate females. 相似文献
147.
凝聚态爆炸危险源外壳对爆炸冲击波影响的研究 总被引:1,自引:2,他引:1
容器中或储罐凝聚态化学危险品爆炸事故时有发生,容器或储罐壁的厚度对事故后果是否有影响,有什么影响,笔者利用非线性动力学有限元程序ANSYS/LS-DYNA,通过数值计算,研究了开阔空间带壳凝聚态爆炸危险源在空气中爆炸时,外壳厚度对爆炸应力波强度的影响。研究结果表明:易爆危险源壳体厚度的变化对爆炸冲击波的传播特性有显著影响。带壳易爆危险源爆炸作用场中的应力波峰值随距离的衰减指数与易爆危险源壳体厚度成线性关系,壳体越厚,衰减指数越大,应力波峰值随距离衰减越快。该结果为预测凝聚态易爆危险源爆炸事故后果,制定应急预案提供了科学依据。 相似文献
148.
149.
An interaction of a detonation wave propagating in the cellular detonation mode with a cloud of inert particles is investigated numerically. The analysis of results allows the regimes of propagation of the heterogeneous plane Chapman–Jouguet and cellular detonations and their suppression to be identified. The influence of various parameters of the inert cloud is demonstrated. The critical length of the cloud sufficient for detonation suppression is determined. It is shown that the disperse composition and the nonuniform distribution of particles in the cloud are important parameters affecting the detonation propagation mode. 相似文献
150.
Zhaoyue Sun Lisha Feng Guodong Fang Longgang Chu Dongmei Zhou Juan Gao 《环境科学学报(英文版)》2021,33(3):248-259
Nano-Fe2O3 embedded in montmorillonite particles (Fe-Mt) were prepared to degrade diethyl phthalate (DEP) with citric acid (CA) under xenon light irradiation. Compared to pristine montmorillonite (Na-Mt), the embedding process increased 14.5-fold of iron content and 1.8-fold of specific surface area. The synthesized Fe-Mt have more oxygen vacancies than Fe2O3 nanoparticles (nFe2O3), which could induce more reactive oxygen species (ROSs) generation in the presence of CA under xenon lamp irradiation. Fe-Mt with CA enhanced photo-assisted degradation of DEP 2.5 times as compared to nFe2O3 with CA. Quenching experiments, electron paramagnetic resonance (EPR) spectroscopy and identification of products confirmed that surface-bound ?OH was the main radical to degrade DEP. Common anions (i.e., NO3?, CO32?, Cl?) and humic acid could compete ?OH with DEP and cause slower degradation of DEP. The removal efficiency of DEP was more than 56% with Fe-Mt after three recycles, and the dissolved Fe concentration from Fe-Mt was below 75 μmol/L, indicating Fe-Mt had a good stability as a catalyst. Fe-Mt together with CA appeared to be a promising strategy to remove organic pollutants in surface water, or topsoil under solar irradiation. 相似文献