全文获取类型
收费全文 | 18787篇 |
免费 | 1463篇 |
国内免费 | 852篇 |
专业分类
电工技术 | 1096篇 |
技术理论 | 1篇 |
综合类 | 1982篇 |
化学工业 | 2678篇 |
金属工艺 | 742篇 |
机械仪表 | 1154篇 |
建筑科学 | 1413篇 |
矿业工程 | 456篇 |
能源动力 | 1047篇 |
轻工业 | 831篇 |
水利工程 | 900篇 |
石油天然气 | 1193篇 |
武器工业 | 202篇 |
无线电 | 699篇 |
一般工业技术 | 2409篇 |
冶金工业 | 872篇 |
原子能技术 | 71篇 |
自动化技术 | 3356篇 |
出版年
2024年 | 26篇 |
2023年 | 181篇 |
2022年 | 225篇 |
2021年 | 361篇 |
2020年 | 375篇 |
2019年 | 428篇 |
2018年 | 454篇 |
2017年 | 594篇 |
2016年 | 645篇 |
2015年 | 713篇 |
2014年 | 849篇 |
2013年 | 1567篇 |
2012年 | 960篇 |
2011年 | 1093篇 |
2010年 | 828篇 |
2009年 | 993篇 |
2008年 | 940篇 |
2007年 | 1052篇 |
2006年 | 1047篇 |
2005年 | 848篇 |
2004年 | 784篇 |
2003年 | 734篇 |
2002年 | 656篇 |
2001年 | 565篇 |
2000年 | 542篇 |
1999年 | 532篇 |
1998年 | 477篇 |
1997年 | 385篇 |
1996年 | 440篇 |
1995年 | 316篇 |
1994年 | 281篇 |
1993年 | 182篇 |
1992年 | 200篇 |
1991年 | 145篇 |
1990年 | 101篇 |
1989年 | 89篇 |
1988年 | 69篇 |
1987年 | 56篇 |
1986年 | 36篇 |
1985年 | 66篇 |
1984年 | 64篇 |
1983年 | 61篇 |
1982年 | 53篇 |
1981年 | 14篇 |
1980年 | 21篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1975年 | 5篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
941.
Justin Salminen Peter Blomberg Jarno Mäkinen Lea Räsänen 《American Institute of Chemical Engineers》2015,61(9):2739-2748
Mining and metals processing are not invisible activities and are heavy industries, which require energy, water, chemicals, and land area. Recently more emphasis is given to environmental and societal aspects in mining and processing. Development of good practices with improved resource efficiency, new recovery methods and sustainability thinking are increasingly required. This work shows pH titration method for acid mine drainage (AMD) water incorporated with aqueous thermodynamic model for selective metals precipitation from complex solution. Also two examples on gold recovery methods from aqueous streams are shown: biosorption using fungal matter and solvent extraction using a task‐specific ionic liquid. By understanding chemical thermodynamics and natural phenomena, there is a better chance of developing solutions for environmental problems and new industrial processes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2739–2748, 2015 相似文献
942.
943.
944.
Dmitry Eskin 《加拿大化工杂志》2015,93(11):2051-2054
945.
采用改进多分辨率快速S变换的电能质量扰动识别 总被引:1,自引:0,他引:1
噪声干扰是影响电能质量暂态扰动识别准确率的最重要因素。经过S变换后获得的扰动信号的模时–频矩阵具有灰度图像特点。因此,可通过二维数学形态学方法,滤除噪声干扰,获得更高的识别准确率。首先,针对扰动信号时–频分布特点,设计具有不同时–频分辨率的多分辨率快速S变换方法以降低运算量、提高特征表现能力;之后,在阈值滤波基础上,根据信号时–频分布特点,选择线段型、零角度结构元进行灰度级形态学开运算,进一步滤除高频频域噪声;最后,从原始信号、信号傅里叶谱、多分辨率快速S变换模矩阵中提取5种特征建立决策树分类器,识别含噪声信号与6种复合扰动信号在内的12种电能质量信号。通过仿真对比实验发现,新方法具有更好的抗噪能力,更加适用于低信噪比环境下的电能质量信号识别。 相似文献
946.
Over the last decade, motorcycle use has been rapidly increasing in Indonesia as have violations of traffic rules committed by motorcyclists. This study aims to explore the impacts of motorcyclists’ attitudes, habits, preferences, and travel patterns on their behaviour in disregarding traffic regulations in three cities in Indonesia. The theory of planned behaviour and structural equation modelling are employed to explore these relationships. Consistent with results from previous studies in developed countries, an individual’s beliefs and attitudes, social norms and perceived behaviour control significantly influence behaviour in disregarding traffic rules. Young adults and students are found to be more likely to frequently violate traffic regulations. However, unlike previous findings from developed countries, in Indonesia, males are less likely to disregard traffic rules than females. Overall, pushing the motorcycle through a (very) narrow gap, speeding, driving recklessly, and overtaking on the wrong side are the most frequent traffic violations that make up repetitive violation behaviour among urban motorcyclists in Indonesia. The results highlight the need to revisit Indonesian National Traffic Law traffic violation classification and penalties and separate violations that are likely to cause fatal results, thus requiring tougher law enforcement, from violations that are unlikely to have fatal consequences. 相似文献
947.
Prediction of the in vivo performance of the drug product from the in vitro studies is the major challenging job for the pharmaceutical industries. From the current regulatory perspective, biorelevant dissolution media should now be considered as quality control media in order to avoid the risk associated. Physiological based pharmacokinetic models (PBPK) coupled with biorelevant dissolution medium is widely used in simulation and prediction of the plasma drug concentration and in vivo drug performance. The present investigation deals with the evaluation of biorelevant dissolution media as well as in vivo drug performance by PBPK modelling using STELLA® simulation software. The PBPK model was developed using STELLA® using dissolution kinetics, solubility, standard gastrointestinal parameters and post-absorptive disposition parameters. The drug product selected for the present study includes Linezolid film-coated immediate-release tablets (Zyvox), Tacrolimus prolonged-release capsules (Advagraf), Valganciclovir tablets (Valcyte) and Mesalamine controlled-release capsules (Pentasa) each belonging to different biopharmaceutics classification system (BCS). The simulated plasma drug concentration was analyzed and pharmacokinetic parameters were calculated and compared with the reported values. The result from the present investigation indicates that STELLA® when coupled with biorelevant dissolution media can predict the in vivo performance of the drug product with prediction error less than 20% irrespective of the dosage form (immediate release versus modified release) and BCS Classification. Thus, STELLA® can be used for in vivo drug prediction which will be helpful in generic drug development. 相似文献
948.
949.
以乙基黄药为捕收剂,硫化钠为硫化剂,通过单矿物浮选试验系统地研究了白铅矿浮选时硫化钠用量、硫化时间、搅拌条件、加药方式以及矿浆p H对硫化过程中矿物的浮游性、矿浆电位、硫离子电极电位的影响。采用多元回归方法建立了浮选回收率与硫化电位的数学模型,数学模型很好地反映了两者之间的关系。使用相关系数法分析了各因素对硫化电位的影响趋势及两者间的相关性。利用Matlab数学软件拟合出硫化电位与主要影响因子间的数学模型方程,再结合回收率与电位的数学模型,可以实现对硫化过程及时、合理的调控。 相似文献
950.
Panagiotis Michalatos 《Architectural Design》2016,86(5):108-115
Does the ontology of design software influence built form? Panagiotis Michalatos , lecturer in architectural technology at Harvard Graduate School of Design and a principal research engineer at Autodesk, Inc, here looks at how the move from drawing typologies to digital modelling since the mid-1990s has affected architectural aesthetics. He goes on to examine two more recent developments that may announce a further paradigm shift: granular tracking of design input, and data organisation practices in biomedics which, transferred to architecture, could allow for a more spatio-temporal approach. 相似文献