全文获取类型
收费全文 | 11232篇 |
免费 | 1271篇 |
国内免费 | 567篇 |
专业分类
电工技术 | 677篇 |
技术理论 | 6篇 |
综合类 | 1204篇 |
化学工业 | 2013篇 |
金属工艺 | 312篇 |
机械仪表 | 328篇 |
建筑科学 | 1708篇 |
矿业工程 | 619篇 |
能源动力 | 764篇 |
轻工业 | 833篇 |
水利工程 | 1520篇 |
石油天然气 | 820篇 |
武器工业 | 32篇 |
无线电 | 298篇 |
一般工业技术 | 520篇 |
冶金工业 | 790篇 |
原子能技术 | 98篇 |
自动化技术 | 528篇 |
出版年
2024年 | 50篇 |
2023年 | 162篇 |
2022年 | 381篇 |
2021年 | 473篇 |
2020年 | 383篇 |
2019年 | 341篇 |
2018年 | 298篇 |
2017年 | 295篇 |
2016年 | 369篇 |
2015年 | 380篇 |
2014年 | 692篇 |
2013年 | 642篇 |
2012年 | 748篇 |
2011年 | 887篇 |
2010年 | 684篇 |
2009年 | 684篇 |
2008年 | 574篇 |
2007年 | 787篇 |
2006年 | 715篇 |
2005年 | 604篇 |
2004年 | 489篇 |
2003年 | 462篇 |
2002年 | 381篇 |
2001年 | 320篇 |
2000年 | 276篇 |
1999年 | 202篇 |
1998年 | 130篇 |
1997年 | 116篇 |
1996年 | 110篇 |
1995年 | 67篇 |
1994年 | 74篇 |
1993年 | 34篇 |
1992年 | 51篇 |
1991年 | 26篇 |
1990年 | 24篇 |
1989年 | 33篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Baak K. Taeli 《Lakes & Reservoirs: Research and Management》2006,11(3):149-168
Lake Mogan, located in the steppes of central Anatolia, is a vital Turkish ecological system, in terms of its water resources, flora and fauna. The lake also is a unique recreational area for Ankara, the capital of Turkey. However, the lake is currently threatened by severe pollution, being under the risk of serious degradation because of (i) uncontrolled urbanization; (ii) point and non‐point source pollution; (iii) inefficient sewerage systems; (iv) sediment transportation and pollution via influent creeks to the lake; (v) uncontrolled soil erosion in its drainage basin; (vi) inappropriate flood control measures; and (vii) severe degradation of the natural wetlands within its drainage basin. This study evaluates the influence of its influent creeks on the water quality of Lake Mogan, mainly because the creeks are believed to be responsible for the major pollutant load reaching the lake, and because the extensive database documenting this situation has not previously been critically evaluated. Accordingly, this study reviews (i) change in the water quality of Lake Mogan between 1993 and 2002; (ii) the water quality classification of the major influent creeks feeding Lake Mogan; and (iii) the influence of the influent creeks on the water quality of the lake between 1993 and 2004. 相似文献
32.
水生生物环境诊断(AOD)技术应用研究 总被引:4,自引:0,他引:4
介绍一种新型的毒性试验方法——水生生物环境诊断(AOD)技术,该方法将冷冻浓缩和生物测试技术有机地相结合,较好地解决了低毒性水体的毒性测试问题。应用本项技术以红鳍鱼为受试生物,分别对湖北武汉马伧湖、墨水湖、广东深圳河、长江干流寸滩等几个断面、丹江口水库白河、丹江河口、老灌河等不同水体进行AOD测试,所得48hr-LC\-50结果与实际水质状况基本相符。 相似文献
33.
We define the hazardous waste management problem as the combined decisions of selecting the disposal method, siting the disposal plants and deciding on the waste flow structure. The hazardous waste management problem has additional requirements depending on the selected disposal method. In this paper we focus on incineration, for which the main additional requirement is to satisfy the air pollution standards imposed by the governmental restrictions. We propose a cost-based mathematical model in which the satisfaction of air pollution standards is also incorporated. We used the Gaussian Plume equation in measuring the air pollution concentrations at population centers. A large-scale implementation of the proposed model within Turkey is provided. 相似文献
34.
唐德修 《成都纺织高等专科学校学报》2007,24(3):13-15
科学焚烧处理垃圾法具有占地少,场地易选择,时间短,减量化显著,无害化彻底以及回收余热供发电供热等优点.其处理设备和控制系统是保证科学焚烧处理垃圾成功,并带来巨大经济效益的关键.鉴于此,文章对科学焚烧垃圾系统设计作了比较详细的介绍. 相似文献
35.
This study focuses on how to assess the optimal environmental investment decisions under economic and ecological uncertainty, and establishes the continuous time model using the real option approach to optimize environmental pollution policy. Unlike traditional cost benefit analysis, this work extends the model of [Pindyck, R.S., 2002. Optimal timing problems in environmental economics. Journal of Economic Dynamics and Control 26(9–10), 1677–1697], and attempts to identify the storage threshold of pollution stocks and the optimal timing for implementing environmental pollution decisions. 相似文献
36.
介绍工业污染源大气污染物排放连续监测系统的系统结构和应用范围。重点讨论一体化工作站在此系统中实际应用和性能特点。 相似文献
37.
38.
The operating conditions of this study are close to the typical operating conditions of flue gas desulfurization system in coal-fired power plants. The aim of this study is to investigate the absorption kinetics of SO2 and NO from simulated flue gas into an aqueous solution of acidic sodium chlorite using a bench-scale spraying column. The range of absorption rates measured in this study is between 1.91×10?11 and 9.59×10?10?mol?s?1?cm?2. The range of rate constants measured in this study is between 1.32×107 and 1.21×108?(L?mol?1)1.9?s?1, and the average rate constant is 6.16×107?(L?mol?1)1.9?s?1. The activation energy and frequency factor are 129 Kcal/mol (53.97 KJ/mol) and 6.93×1016?[(L/mol)1.9/s], respectively. 相似文献
39.
模拟我国南方沿海浪溅区和水位变动区的海工钢筋混凝土结构物的腐蚀环境,对掺入粉煤灰和矿渣的混凝土抗氯离子侵蚀性进行了试验。结果表明,在水灰比相同的条件下,加掺和料的混凝土抗氯离子侵蚀性高于普通混凝土。 相似文献
40.