全文获取类型
收费全文 | 15555篇 |
免费 | 1902篇 |
国内免费 | 1470篇 |
专业分类
电工技术 | 690篇 |
技术理论 | 5篇 |
综合类 | 2134篇 |
化学工业 | 888篇 |
金属工艺 | 484篇 |
机械仪表 | 771篇 |
建筑科学 | 1522篇 |
矿业工程 | 403篇 |
能源动力 | 308篇 |
轻工业 | 937篇 |
水利工程 | 555篇 |
石油天然气 | 1365篇 |
武器工业 | 115篇 |
无线电 | 1858篇 |
一般工业技术 | 1026篇 |
冶金工业 | 317篇 |
原子能技术 | 156篇 |
自动化技术 | 5393篇 |
出版年
2024年 | 55篇 |
2023年 | 176篇 |
2022年 | 336篇 |
2021年 | 388篇 |
2020年 | 444篇 |
2019年 | 365篇 |
2018年 | 373篇 |
2017年 | 462篇 |
2016年 | 501篇 |
2015年 | 602篇 |
2014年 | 854篇 |
2013年 | 861篇 |
2012年 | 1027篇 |
2011年 | 1230篇 |
2010年 | 1005篇 |
2009年 | 1061篇 |
2008年 | 1114篇 |
2007年 | 1320篇 |
2006年 | 1153篇 |
2005年 | 941篇 |
2004年 | 843篇 |
2003年 | 667篇 |
2002年 | 551篇 |
2001年 | 413篇 |
2000年 | 342篇 |
1999年 | 304篇 |
1998年 | 254篇 |
1997年 | 186篇 |
1996年 | 176篇 |
1995年 | 168篇 |
1994年 | 165篇 |
1993年 | 106篇 |
1992年 | 88篇 |
1991年 | 58篇 |
1990年 | 50篇 |
1989年 | 52篇 |
1988年 | 23篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 32篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1975年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
An integrated technique that embeds civilized swarm optimization (CSO) and Powell’s pattern search (PPS) method is proposed to search economic dispatch of combined heat and power (CHP) dispatch problem. In the proposed technique, CSO is selected as global search technique and PPS is undertaken as a local search technique. Civilized swarm optimization is having attributes of particle swarm optimization (PSO) and society civilization algorithm (SCA). In CSO, mutually interacting societies forms the civilization. The positions of society particles are updated through the guidance of own leader along with their best positions. The best performing particle of CSO is further improved by PPS method based on a certain set criterion. The PPS method is based on the conjugate search direction method and does not require the gradient or Hessian matrix of the function to be optimized. The CHP dispatch problem has a mutual dependency of demand and heat-power capacity of generating units, so it requires an effective constraint handling strategy. In this work, variable reduction strategy with exterior penalty method is applied to satisfy equality constraints. The proposed technique is tested on five CHP test systems considering valve-point loading effect, prohibited operating zones constraint, and transmission losses. The obtained results are compared to the results reported in the literature and found satisfactory. Further, for verification of statistical performance of the proposed technique, t-test and Wilcoxon signed rank test is also performed. 相似文献
992.
993.
该文结合生物学"共生"理论,以共生模式为切入点,探讨绿化系统与高层住宅的结合问题。文中分析了高层住宅中点共生、间歇共生、连续共生、一体化共生四种绿化模式,提出了结合功能、物种多样化和协同共管的共生策略。 相似文献
994.
基于改进FAHP方法谈我国铁路BOT融资项目的风险 总被引:1,自引:0,他引:1
解析了铁路BOT融资项目各风险因素,运用改进的FAHP方法对其进行了研究,计算出各风险因素权重,找出其中的主要风险,为项目风险决策提供依据,对传统FAHP方法进行改进,提高其判断矩阵的一致性,保证分析结果的可靠性。 相似文献
995.
徐宁 《电气电子教学学报》2012,34(3):103-105
针对专业课的特点和教学要求,本文研究探索如何将研究型教学理念贯穿于"物理光学"教学过程中,通过对研究型教学内涵的分析,介绍了教学改革的具体措施与实施过程。实践表明,研究型教学理念的应用有助于调动学生的积极性,培养学生的创新能力和团队意识,取得很好的教学效果。 相似文献
996.
分析了工厂模式的特点,阐述了分层架构体系的设计思路。以数据访问层的设计为例,从设计模式的角度探讨了可复用的数据访问层的实现方法,并重点分析了工厂模式的具体应用过程。 相似文献
997.
We are presenting an innovative, massively-parallel heterogeneous architecture for the very fast construction and implementation of very large Aho–Corasick and Commentz-Walter pattern-matching automata, commonly used in data-matching applications, and validate its use with large sets of data actively used in intrusion detection systems. Our approach represents the first known hybrid-parallel model for the construction of such automata and the first to allow self-adjusting pattern-matching automata in real-time by allowing full-duplex transfers at maximum throughput between the host (CPU) and the device (GPU). The architecture we propose is easily scalable to multi-GPU and multi-CPU systems and benefits greatly from GPU acceleration, also relying on a highly-efficient storage model for the automata and includes on-demand support for regular-expression matching, as well as support for custom heuristics to be built on top of the architecture, at different processing stages. 相似文献
998.
999.
针对某款变频新国标机器匹配过程中出现制冷能力不稳定、蒸发器没有进行充分换热的情况,主要从以下两方面进行优化,解决了以上问题:1通过Wei sman流型图定量分析确定了分流器要达到雾状流所需要的孔径;2通过布热电偶数据判断每一路的蒸发情况来最终确定U管数量及分流毛细管长度,保证蒸发器充分换热。最终确定该款变频新国标机器采用D5蒸发器、¢4孔径分流器的方案,实现能力达到稳定且APF能够满足新国标3.35的要求。 相似文献
1000.
Patterns in melanocytic lesions: impact of the geometry on growth and transport inside the epidermis
Thibaut Balois Clément Chatelain Martine Ben Amar 《Journal of the Royal Society Interface》2014,11(97)
In glabrous skin, nevi and melanomas exhibit pigmented stripes during clinical dermoscopic examination. They find their origin in the basal layer geometry which periodically exhibits ridges, alternatively large (limiting ridges) and thin (intermediate ridges). However, nevus and melanoma lesions differ by the localization of the pigmented stripes along furrows or ridges of the epidermis surface. Here, we propose a biomechanical model of avascular tumour growth which takes into account this specific geometry in the epidermis where both kinds of lesions first appear. Simulations show a periodic distribution of tumour cells inside the lesion, with a global contour stretched out along the ridges. In order to be as close as possible to clinical observations, we also consider the melanin transport by the keratinocytes. Our simulations show that reasonable assumptions on melanocytic cell repartition in the ridges favour the limiting ridges of the basal compared with the intermediate ones in agreement with nevus observations but not really with melanomas. It raises the question of cell aggregation and repartition of melanocytic cells in acral melanomas and requires further biological studies of these cells in situ. 相似文献