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91.
Cyanobacterial (Blue-Green Algal) Toxins and their Significance in UK and European Waters 总被引:2,自引:0,他引:2
The cyanobacteria (blue-green algae) which commonly produce mass developments in fresh and saline waters are capable of producing toxins. These compounds have been responsible for the deaths of animals, birds and fish in many countries, and have been linked with several forms of human illness through skin contact and ingestion. Evidence has accumulated over the past decade that cyanobacterial toxins occur commonly in European waters which contain cyanobacterial mass growths. This paper summarizes the recent published occurrence and types of cyanobacterial toxins found in European waters with reference to poisoning incidents.
Cyanobacterial blooms were particularly abundant in the warm dry summer of 1989 in the UK. The deaths of sheep and dogs and the cases of human illness that were ascribed to cyanobacterial toxins were followed by a more intensive and wider investigation into the extent of cyanobacterial toxicity in UK waters than had hitherto been undertaken. Of the cyanobacterial blooms sampled from over 90 freshwaters, approximately two-thirds were toxic (lethal) according to mouse bioassay. Short-term and long-term needs for the recognition, quantification and management of problems which can be caused by potentially toxigenic cyanobacteria in water-bodies used for recreation, aquaculture and potable supply are briefly discussed. 相似文献
Cyanobacterial blooms were particularly abundant in the warm dry summer of 1989 in the UK. The deaths of sheep and dogs and the cases of human illness that were ascribed to cyanobacterial toxins were followed by a more intensive and wider investigation into the extent of cyanobacterial toxicity in UK waters than had hitherto been undertaken. Of the cyanobacterial blooms sampled from over 90 freshwaters, approximately two-thirds were toxic (lethal) according to mouse bioassay. Short-term and long-term needs for the recognition, quantification and management of problems which can be caused by potentially toxigenic cyanobacteria in water-bodies used for recreation, aquaculture and potable supply are briefly discussed. 相似文献
92.
针对高磷鲕状赤铁矿石矿物结构复杂导致的脱磷困难现状,为实现深度脱磷的目的,探索矿物还原过程中磷的形态及微观脱磷过程。以铁品位为44.78%、磷的质量分数为0.92%的高磷鲕状赤铁矿为研究对象,根据其面扫描电镜及矿相结构图可知,矿物之间嵌布紧密、逐层形成鲕状结构,石英、鲕绿泥石与赤铁矿等互相包裹,磷元素集中分布在鲕粒内部的氟磷灰石中。通过对焙烧产物做扫描电镜(SEM)及能谱分析(EDS),对高磷鲕状赤铁矿脱磷机理进行研究。研究结果表明,当YM-1脱磷剂质量分数为16%,还原过程中鲕状结构被破坏,金属铁逐渐从鲕粒中析出聚集,脉石与铁颗粒分离明显,磷化为不同形态被脱除。磁选后尾矿、铁分离完全,磷元素几乎全部进入尾矿,添加复合脱磷剂YM-1焙烧磁选后铁精矿的铁品位为90.16%,铁回收率为91.25%,磷质量分数为0.056%,脱磷率为93.91%。铁精粉各项指标满足工业冶炼要求。 相似文献
93.
在大别山区的变质地层中,于茅山─兰溪和烽火山─回龙山一带,分布着一套含磷、石墨和富白云质及硅质的岩层。采用岩石切片法,在其中发现了一些古菌、藻类炭质残骸,这些化石多数为超微体,细胞结构简单,呈群体共生或连生,二分裂、断殖和出芽生殖现象明显。其类型和形态有一定分异,且出现属真核生物的古酵母菌。其时代为早元古代。 相似文献
94.
95.
Slag/metal separation process of the highly reduced oolitic high-phosphorus iron ore fines was investigated. Samples were prepared using the reduced ore fines (metallization rate: 88%) and powder additives of CaO and Na2CO3. Slag/metal separation behavior tests were conducted using a quenching method and the obtained metal parts were subjected to direct observation as well as microstructure examination with SEM and EDS; iron recovery and phosphorus distribution tests were conducted using a Si-Mo high temperature furnace and the obtained metal parts were examined by ICP-AES analysis and mass measurement. Thermodynamic calculation using coexistence theory of slag structure was also performed. Results show that temperature for slag/metal separation must be higher than 1823 K and a satisfying slag/metal separation of the highly reduced ore fines needs at least 4 min; phosphorus con- tent of hot metal is mainly determined by thermodynamics; temperature of 1823-1873 K and Na2CO3 mixing ratio of about 3 % are adequate for controlling phosphorus content to be less than 0.3 mass% in hot metal; temperature, time and Na2CO3 mixing ratio do not have significant effect on iron recovery, and iron recovery rate could be higher than 80% as long as a good slag/metal separation result is obtained. 相似文献
96.
97.
Nitrogen and phosphorus removal from municipal wastewater effluent using microalgal biofilms 总被引:4,自引:0,他引:4
Microalgal biofilms have so far received little attention as post-treatment for municipal wastewater treatment plants, with the result that the removal capacity of microalgal biofilms in post-treatment systems is unknown. This study investigates the capacity of microalgal biofilms as a post-treatment step for the effluent of municipal wastewater treatment plants. Microalgal biofilms were grown in flow cells with different nutrient loads under continuous lighting of 230 μmol/m2/s (PAR photons, 400-700 nm). It was found that the maximum uptake capacity of the microalgal biofilm was reached at loading rates of 1.0 g/m2/day nitrogen and 0.13 g/m2/day phosphorus. These maximum uptake capacities were the highest loads at which the target effluent values of 2.2 mg/L nitrogen and 0.15 mg/L phosphorus were still achieved. Microalgal biomass analysis revealed an increasing nitrogen and phosphorus content with increasing loading rates until the maximum uptake capacities. The internal nitrogen to phosphorus ratio decreased from 23:1 to 11:1 when increasing the loading rate. This combination of findings demonstrates that microalgal biofilms can be used for removing both nitrogen and phosphorus from municipal wastewater effluent. 相似文献
98.
99.
Modification, calibration and verification of the IWA River Water Quality Model to simulate a pilot-scale high rate algal pond 总被引:1,自引:0,他引:1
We implemented the IWA River Water Quality Model No. 1 (Reichert et al., 2001. River Water Quality Model No. 1, IWA Scientific & Technical Report No. 12) to simulate water-quality characteristics in two pilot-scale High Rate Algal Ponds. Simulation results were compared with two years' of data from the ponds. The first year's data from one pond were used for model calibration; the remaining data were used for validation. As originally formulated and parameterized, the model consistently yielded summer-time algal biomass concentrations which were too low - with consequent failures in its reproduction of dissolved oxygen, pH and nutrient dynamics. We experimented with various structural/parametric changes to improve the model's performance. The most effective strategy was to greatly increase the respiratory losses suffered by the heterotrophic osmotrophs (thereby giving the algae access to a larger fraction of the incoming dissolved organic carbon and nitrogen). This suggests that CO2-bubbling alone cannot entirely preclude resource-limitation of algal production. We doubt that our parameterization of heterotrophic osmotrophs is correct and infer that the algae derive a large fraction of their nutrition by direct osmotrophic uptake of dissolved organic matter. This inference is supported by the literature concerning the physiology of the dominant algal species in our ponds. 相似文献
100.
针对彝良难选鲕状赤褐铁矿进行了系统的选矿试验研究,采用强磁选—反浮选及选择性絮凝浮选脱泥—反浮选均可以得到较好的选别指标:在强磁选—反浮选小型闭路试验中可以得到铁品位54.70%、回收率达79.44%、含磷仅0.17%的铁精矿;在选择性絮凝后浮选脱泥—反浮选的工艺流程中可以得到铁品位54.63%、铁回收率达77.62%、含磷仅0.15%的铁精矿. 相似文献