全文获取类型
收费全文 | 26787篇 |
免费 | 687篇 |
国内免费 | 34篇 |
专业分类
电工技术 | 329篇 |
综合类 | 14篇 |
化学工业 | 5929篇 |
金属工艺 | 517篇 |
机械仪表 | 465篇 |
建筑科学 | 1160篇 |
矿业工程 | 332篇 |
能源动力 | 650篇 |
轻工业 | 1725篇 |
水利工程 | 226篇 |
石油天然气 | 245篇 |
无线电 | 1712篇 |
一般工业技术 | 4081篇 |
冶金工业 | 6147篇 |
原子能技术 | 265篇 |
自动化技术 | 3711篇 |
出版年
2022年 | 246篇 |
2021年 | 413篇 |
2020年 | 266篇 |
2019年 | 346篇 |
2018年 | 422篇 |
2017年 | 369篇 |
2016年 | 485篇 |
2015年 | 391篇 |
2014年 | 614篇 |
2013年 | 1652篇 |
2012年 | 939篇 |
2011年 | 1202篇 |
2010年 | 922篇 |
2009年 | 971篇 |
2008年 | 1154篇 |
2007年 | 1064篇 |
2006年 | 974篇 |
2005年 | 881篇 |
2004年 | 743篇 |
2003年 | 711篇 |
2002年 | 705篇 |
2001年 | 485篇 |
2000年 | 390篇 |
1999年 | 447篇 |
1998年 | 440篇 |
1997年 | 427篇 |
1996年 | 473篇 |
1995年 | 444篇 |
1994年 | 451篇 |
1993年 | 436篇 |
1992年 | 431篇 |
1991年 | 271篇 |
1990年 | 410篇 |
1989年 | 387篇 |
1988年 | 336篇 |
1987年 | 404篇 |
1986年 | 348篇 |
1985年 | 441篇 |
1984年 | 464篇 |
1983年 | 398篇 |
1982年 | 375篇 |
1981年 | 297篇 |
1980年 | 298篇 |
1979年 | 357篇 |
1978年 | 299篇 |
1977年 | 238篇 |
1976年 | 217篇 |
1975年 | 245篇 |
1974年 | 217篇 |
1973年 | 224篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Robert E. Wallace 《Information Systems Management》2013,30(1):65-67
Although most organizations realize the need to shift the emphasis in systems development from transactional systems to tactical and strategic systems, they are often reluctant or unable to do so. This column examines the reasons for this and discusses how MIS managers can motivate both users and senior managers to develop these systems. 相似文献
102.
Robert E. Wallace 《Information Systems Management》2013,30(1):93-96
Abstract A large portion of the literature about business and information systems is written at the grand, strategic level. That is certainly the case for the first two books reviewed in this column. One deals with the broad implications of the shift of routine IT work to Asia and the potential for this shift to expand into development and concepts. The other presents a framework for ameliorating IT risk. The third book is concerned with the nitty gritty of the little decisions, made over and over, in day-to-day operations. The focus is on ways of improving and automating these decisions to gain strategic advantage. And, as you would expect, this third book is much longer and much more detailed than the first two. 相似文献
103.
Andrew Morrison Geska Helena Andersson Robert Brečević Synne Skjulstad 《Digital Creativity》2013,24(1-2):3-20
The metaphor of plasma is taken up to present and discuss movement and engagement by participants in mixed reality installation arts. Two works involving full body video portraits exhibited through large plasma screens in a variety of public settings are covered. Machinic mediations of video realism are considered in terms of embodied interaction in which viewer-participants contribute to the ‘disquiet’ of gendered figuring. Processural, proximal and personal aspects of responsive engagement are discussed. This is extended to performativity that may lead us to critical reflection of our own actions and responses in mixed reality arts. 相似文献
104.
Havasi Catherine Speer Robert Pustejovsky James Lieberman Henry 《Intelligent Systems, IEEE》2009,24(4):24-35
Understanding the world we live in requires access to a large amount of background knowledge: the commonsense knowledge that most people have and most computer systems don't. Many of the limitations of artificial intelligence today relate to the problem of acquiring and understanding common sense. The Open Mind Common Sense project began to collect common sense from volunteers on the Internet starting in 2000. The collected information is converted to a semantic network called ConceptNet. Reducing the dimensionality of ConceptNet's graph structure gives a matrix representation called AnalogySpace, which reveals large-scale patterns in the data, smoothes over noise, and predicts new knowledge. Extending this work, we have created a method that uses singular value decomposition to aid in the integration of systems or representations. This technique, called blending, can be harnessed to find and exploit correlations between different resources, enabling commonsense reasoning over a broader domain. 相似文献
105.
106.
107.
David G. James Robert J. Bartelt Richard J. Faulder 《Journal of chemical ecology》1994,20(11):2805-2819
Synthetic aggregation pheromones ofCarpophilus hemipterus (L.) andCarpophilus mutilatus Erichson were field tested during a 10-month period in southern New South Wales stone fruit orchards to determineCarpophilus spp. phenology and the effect of two pheromone doses on attraction. Aggregation pheromones synergize the attraction of host volatiles toCarpophilus spp. Four major species,C. hemipterus, C. mutilatus, C. davidsoni Dobson andC. (Urophorus) humeralis (F.), were trapped, with greater numbers of each species inC. hemipterus pheromone/fermenting whole-wheat breaddough-baited traps, than in dough-only-traps. InC. mutilatus pheromone/ fermenting-dough-baited traps, onlyC. mutilatus andC. davidsoni responded in greater numbers than to dough-only traps. Beetles first appeared in traps in late September (early spring) when daily maximum temperatures averaged 17.5C. Trappings reached a peak during October and declined to very low levels in November–December (late spring-early summer). Numbers trapped of all species increased during February–March (late summer–early autumn), presumably due to the presence of abundant host resources (ripening and fallen fruit), and continued at high levels until May (late autumn). An 18-week study demonstrated significantly greater responses byCarpophilus spp. to 5000-g than to 500-g doses of C.hemipterus andC. mutilatus pheromones. Greatest responses to 5000g were recorded forC. hemipterus andC. mutilatus responding to their own pheromones (increased attraction over dough alone of 259x and 21.2x respectively). Implications of the study and the potential for using synthetic aggregation pheromones for managingCarpophilus spp. populations in Australian stone fruit are discussed. 相似文献
108.
109.
110.
Classical Cartesian domain decompositions for parallel lattice Boltzmann simulations of fluid flow through heterogeneous porous media are doomed to workload imbalance as the number of processors increases, thus leading to decreasing parallel performance. A one-lattice lattice Boltzmann method (LBM) implementation with vector data structure combined with even fluid node partitioning domain decomposition and fully-optimized data transfer layout is presented. It is found to provide nearly-optimal workload balance, lower memory usage and better computational performance than classical slice decomposition techniques using sparse matrix data structures. Predictive memory usage and parallel performance models are also established and observed to be in very good agreement with data corresponding to numerical fluid flow simulations performed through 3-dimensional packings of cylinders and polydisperse spheres. 相似文献