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251.
目的 对贮存周期内包含多个温度环境剖面的固体火箭发动机橡胶密封圈贮存寿命进行评估。方法 通过开展硅橡胶材料加速老化试验,结合Arrhenius老化规律,建立硅橡胶老化模型,获得硅橡胶加速老化等当规律,并根据等当关系开展模拟密封装置加速老化试验,考核老化后硅橡胶密封性。最后通过对固体火箭发动机贮存环境剖面进行梳理,计算出贮存周期下的等效温度,并结合试验获得的硅橡胶密封圈老化性能,直接对该贮存周期下密封圈老化寿命进行评估。结果 通过硅橡胶材料老化试验及模拟密封装置老化试验,得到了25℃下硅橡胶能够满足20 a的使用寿命。随后通过梳理并计算得出固体火箭发动机贮存周期下的等效温度为22.78℃,可以直接获得该发动机使用的硅橡胶密封圈寿命在该贮存环境下能够满足20 a使用寿命。结论 通过计算贮存周期下多个温度环境剖面的等效温度,并结合加速老化试验结论,可快速获得橡胶密封圈老化寿命。 相似文献
252.
目的 厘清某型引信在贮存14 a后的失效模式,研究温度周期性交变对引信及其薄弱零件的影响。方法利用ANSYS workbench软件,建立基于时间硬化的蠕变仿真方法。以某型引信为研究对象,开展周期性温度交变的蠕变仿真,根据仿真计算结果和实物的对比分析,找出薄弱零件,分析其老化失效模式。结果 在每个周期内环境温度循环条件下,仿真时长设定为14 a,结果显示,引信整体蠕变应变率超过1%,平均压紧应力下降21%,松弛稳定性变弱,密封性在一定程度上变差。其中,引信电机外壳、电机扇叶、底部线路对接板为薄弱零件,容易发生失效行为。结论 引信贮存在典型西南湿热环境14 a后,周期性温度交变应力将导致引信出现缺陷,缺陷集中在电机外壳、电机扇叶、底部线路对接板处,应重点对这些部位进行防护。 相似文献
253.
Commercial forestry plantations as a postmining land use in the Upper Hunter Valley of New South Wales, Australia are restricted
by both the poor nutrient availability of mining substrates and low regional rainfall. An experiment was conducted to investigate
whether municipal waste products and saline groundwater from coal mining operations could improve early tree growth without
impacting on the environment through salt accumulation and/or nutrient enrichment and changes in groundwater quality. Potential
impacts were investigated by quantifying the nutrient cycling dynamics within the plantation using an input–output mass balance
approach for exchangeable calcium (Ca2+), exchangeable magnesium (Mg2+), exchangeable potassium (K+), exchangeable sodium (Na+), nitrogen (N), and phosphorus (P). Measured inputs to and outputs from the available nutrient pool in the 0–30 cm of the
overburden subsystem were used to estimate the net effect of unmeasured inputs and outputs (termed “residuals”). Residual
values in the mass balance of the irrigated treatments demonstrated large leaching losses of exchangeable Ca, Mg, K, and Na.
Between 96% and 103% of Na applied in saline mine-water irrigation was leached below the 0–30-cm soil profile zone. The fate
of these salts beyond 30 cm is unknown, but results suggest that irrigation with saline mine water had minimal impact on the
substrate to 30 cm over the first 2 years since plantation establishment. Accumulations of N and P were detected for the substrate
amendments, suggesting that organic amendments (particularly compost) retained the applied nutrients with very little associated
losses, particularly through leaching. 相似文献
254.
Several experiments were performed to evaluate the fertilization capability of Paracentrotus lividus sea urchin gametes, which are usually used in fertilization tests, but which, until now, were employed only for few hours after spawning.The aim of this work is to evaluate the possibility of performing the bioassay for longer periods, employing ‘conserved' gametes. As far as the method, the sperm was stored ‘dry' at 4 ∘C; eggs were conserved in an antibiotic solution at 4 ∘C, and they were exposed both to copper solutions as reference toxicant and to aqueous matrices.The use of conserved gametes in the fertilization bioassay lead to EC50 values which were acceptable for about 3 days. Moreover, these experiments permitted to identify the limiting factor: the male gamete. 相似文献
255.
The human-driven loss of biodiversity has numerous ecological, social, and economic impacts at the local and global levels, threatening important ecological functions and jeopardizing human well-being. In this perspective, we present an overview of how tropical defaunation—defined as the disappearance of fauna as a result of anthropogenic drivers such as hunting and habitat alteration in tropical forest ecosystems—is interlinked with four selected Sustainable Development Goals (SDGs). We discuss tropical defaunation related to nutrition and zero hunger (SDG 2), good health and well-being (SDG 3), climate action (SDG 13), and life on land (SDG 15). We propose a range of options on how to study defaunation in future research and how to address the ongoing tropical defaunation crisis, including but not limited to recent insights from policy, conservation management, and development practice. 相似文献
256.
电厂燃煤的安全贮存管理 总被引:1,自引:0,他引:1
电厂燃煤的安全贮存管理是发电用煤的质量保障.燃煤的贮存点选择,库存组成定额及煤的组堆等防损耗方法直接关系到电力生产的安全和效益. 相似文献
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260.
Industrial technical accidents caused by natural disasters are defined as Natech accidents, such as earthquakes and landslides, which can cause tremendous damage to industrial storage tanks, and lead to accidental leakage and even serious fire and explosion accidents. In this study, a landslide-induced storage tank accident model under earthquake disasters was proposed, and the relationship between landslide mass impact and target impact resistance was taken into account. Also, tank failure and the formation of the pool fire were considered to be the consequences of the Natech accident. Through scenario deduction, the dynamic process of landslide Natech was transformed qualitatively into a disaster chain network diagram composed of a scenario state, a disaster-causing factor and emergency management. The Bayesian network was used to learn and deduce the parameters of the network diagram, and in this process, the prior probability and conditional probability of nodes were obtained primarily by Monte Carlo simulation, and by an improved expert scoring method based on the fuzzy set theory. Through visualization software, the sensitivity analysis of landslide Natech was achieved. Finally, a case study of a liquor storage tank area in Guizhou Province, China was carried out, and the results show that a large amount of hazardous material leakage caused by buckling is key to the formation of pool fire accidents, and several prevention measures for earthquake-induced landslide Natech was proposed according to the sensitivity analysis. 相似文献