全文获取类型
收费全文 | 394篇 |
免费 | 48篇 |
国内免费 | 85篇 |
专业分类
安全科学 | 145篇 |
废物处理 | 13篇 |
环保管理 | 41篇 |
综合类 | 198篇 |
基础理论 | 33篇 |
污染及防治 | 41篇 |
评价与监测 | 14篇 |
社会与环境 | 5篇 |
灾害及防治 | 37篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 28篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 34篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 38篇 |
2011年 | 25篇 |
2010年 | 30篇 |
2009年 | 28篇 |
2008年 | 18篇 |
2007年 | 33篇 |
2006年 | 22篇 |
2005年 | 32篇 |
2004年 | 26篇 |
2003年 | 17篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有527条查询结果,搜索用时 875 毫秒
61.
Vikram J. Kaku Michel C. Boufadel Albert D. Venosa James Weaver 《Environmental Fluid Mechanics》2006,6(4):385-406
The evaluation of dispersant effectiveness used for oil spills is commonly done using tests conducted in laboratory flasks.
We used a Hot Wire Anemometer (HWA) to characterize mixing dynamics in the Swirling Flask (SF) and the Baffled Flask (BF),
the latter is being considered by the EPA to replace the prior to test dispersant effectiveness in the laboratory. Five rotation
speeds of the orbital shaker carrying the flasks were considered, Ω = 50, 100, 150, 175 and 200 rpm. The radial and azimuthal
water speeds were measured for each Ω. It was found that the flow in the SF is, in general, two-dimensional changing from
horizontal at low Ω to axi-symmetric at high Ω. The flow in the BF appeared to be three-dimensional at all rotation speeds.
This indicates that the BF is more suitable for representing the (inherently) 3-D flow at sea. In the SF, the speeds and energy
dissipation rates ɛ increased gradually as the rotation speed increased. Those in the BF increased sharply at rotation speeds
greater than 150 rpm. At 200 rpm, the Kolmogorov scale (i.e., size of smallest eddies) was about 250 and 50 μm in the SF and
BF, respectively. Noting that the observed droplet sizes of dispersed oils range from 50 to 400 μm (hence most of it is less
than 250 μm), one concludes that the mixing in the SF (even at 200 rpm) is not representative of the vigorous mixing occurring
at sea. 相似文献
62.
切断位置对赤子爱胜蚓再生速度的影响 总被引:4,自引:0,他引:4
将赤子爱胜蚓从脑、生殖环部位和总体节的 1/ 2和 3/ 4的位置切断 ,得到有头无尾、无头无尾、无头有尾 3种类型 16个处理体段 ,在 (2 0± 1)℃人工气候箱中培养 ,测定其再生速度 .结果表明 ,赤子爱胜蚓切断的位置不同 ,其再生速度不同 .其中 ,脑部的存在与否 ,对再生速度没有显著的影响 .但是生殖环存在的处理比切除生殖环的处理再生速度快 ,且存活率高 .无头无尾体段再生前部和再生后部的比较表明 ,再生前部比再生后部慢 .体节的损失越少 ,再生的速度越快 .图 6表 3参 11 相似文献
63.
Sperm competition models on the evolution of sperm size assume associations with another sperm quality trait, sperm longevity. Sperm length can also provide an indication of possible mechanisms affecting motility and thus fertilization success. Despite their importance, however, detailed mechanisms of sperm competition at the gamete level are poorly understood. In simultaneously hermaphroditic land snails, sperm traits and cryptic female choice are assumed to be crucial in determining fertilization success. We examined the variation in sperm length and number among individuals from four natural populations of the land snail Arianta arbustorum, a species with multiple mating and long-term sperm storage. We also assessed variation in velocity, motility and longevity of sperm in snails from two of the four populations. Independent of shell size, sperm length differed among populations and, to a minor extent, even among individuals within populations. Mean sperm length of a snail was not correlated with the number of sperm delivered in a spermatophore. The mean sperm velocity (=VCL) did not differ between snails from two populations. However, VCL varied among snails. Percentage motility and longevity of sperm differed between snails from the two populations. No correlations were found between length, velocity, percentage motility and longevity of sperm. To conclude, individual snails differed in sperm quality, and this variation may partly explain the differential fertilization success between A. arbustorum snails. Moreover, our findings did not support the positive association between sperm length and longevity assumed by sperm competition models for internally fertilizing species. 相似文献
64.
顾志龙 《中国安全科学学报》1998,8(1):73-77
论述了将小型链条炉排工业锅炉的炉拱设计成在运行中可以全量调节的结构,以适应燃用多种煤种的需要,并减少与固定拱操作有关的意外伤亡事故。这项技术有创新性,适用性和推广价值 相似文献
65.
介绍了舰艇常用材料在海水环境动态高流速条件下自然电位、自然腐蚀率、电偶腐蚀等多方面的腐蚀实验方法及实验结果,得出了舰艇常用系列材料在动态海水中的腐蚀基本数据以及变化规律,为在舰船设计中材料的选择及腐蚀防护方案的制定提供参考。 相似文献
66.
67.
68.
为研究雨水管道沉积物的沉淀特性和污染物含量特征,在武汉市对建筑(包括住宅小区)、道路和绿地3种用地类型的雨水管道沉积物进行采样和分析.沉速测试结果表明,高沉速颗粒在沉积物中所占比例较大,建筑和道路中沉积物的沉速分布相对稳定,建筑、道路和绿地中沉速大于3.00 cm·s-1的颗粒占比依次递减.粒径分析结果显示,沉积物粒径分布范围较广,大多集中在13~628μm范围内,且同种用地类型沉积物粒径分布差别很大.按沉降速度将每份沉积物样品分为7组,分析化学需氧量(COD)、总氮(TN)和总磷(TP)含量与沉降速度之间的联系.结果表明,沉速大于3.00 cm·s-1和小于0.025cm·s-1的沉积物中污染物含量较低,但高沉速沉积物中污染物总量较多.对沉积物样品整体而言,各用地类型COD含量从高到低依次为:绿地道路建筑;道路雨水管道沉积物中氮含量较低,其余两种用地中含量接近;建筑区雨水管道沉积物中磷含量较高,其余两种用地中含量接近;COD∶TN在(51~89)∶1之间,COD∶TP的值在(102~186)∶1之间. 相似文献
69.
为了解三峡库区腹地大气中活性氮的组成及干沉降通量,于2015年每个季节选取代表性月份在万州城区采集了气体和颗粒物样品.利用离子色谱法测定氮素浓度,同时结合大叶阻力模型模拟计算的干沉降速率值,估算了不同形态氮素的干沉降通量.结果表明,HNO3的干沉降速率值最大,年均值为0.39cm/s,约为其它氮素的3~8倍.NO2和NH3是大气活性氮的主要赋存形态,年均浓度值分别为(11.7±3.9)和(11.0±5.3)μg N/m3,两者之和约占总无机氮浓度的80%.万州城区总无机氮干沉降总量为8.5kg N/(hm2·a),其中氧化态氮(NO2、HNO3、颗粒态NO3-)和还原态氮(NH3、颗粒态NH4+)干沉降通量分别为3.5,5.0kg N/(hm2·a),占干沉降总量的41.4%和58.6%.因此,为有效控制三峡库区腹地的氮素污染,应重点关注NH3的减排. 相似文献
70.