全文获取类型
收费全文 | 5430篇 |
免费 | 184篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 57篇 |
综合类 | 1篇 |
化学工业 | 953篇 |
金属工艺 | 85篇 |
机械仪表 | 91篇 |
建筑科学 | 313篇 |
矿业工程 | 18篇 |
能源动力 | 134篇 |
轻工业 | 499篇 |
水利工程 | 48篇 |
石油天然气 | 38篇 |
武器工业 | 1篇 |
无线电 | 355篇 |
一般工业技术 | 934篇 |
冶金工业 | 1125篇 |
原子能技术 | 20篇 |
自动化技术 | 951篇 |
出版年
2023年 | 30篇 |
2022年 | 34篇 |
2021年 | 88篇 |
2020年 | 75篇 |
2019年 | 69篇 |
2018年 | 98篇 |
2017年 | 75篇 |
2016年 | 127篇 |
2015年 | 90篇 |
2014年 | 161篇 |
2013年 | 355篇 |
2012年 | 255篇 |
2011年 | 335篇 |
2010年 | 232篇 |
2009年 | 198篇 |
2008年 | 266篇 |
2007年 | 239篇 |
2006年 | 196篇 |
2005年 | 202篇 |
2004年 | 150篇 |
2003年 | 134篇 |
2002年 | 135篇 |
2001年 | 86篇 |
2000年 | 77篇 |
1999年 | 88篇 |
1998年 | 140篇 |
1997年 | 132篇 |
1996年 | 95篇 |
1995年 | 90篇 |
1994年 | 68篇 |
1993年 | 78篇 |
1992年 | 85篇 |
1991年 | 50篇 |
1990年 | 61篇 |
1989年 | 57篇 |
1988年 | 55篇 |
1987年 | 57篇 |
1986年 | 60篇 |
1985年 | 73篇 |
1984年 | 59篇 |
1983年 | 73篇 |
1982年 | 57篇 |
1981年 | 40篇 |
1980年 | 50篇 |
1979年 | 67篇 |
1978年 | 51篇 |
1977年 | 49篇 |
1976年 | 48篇 |
1975年 | 41篇 |
1972年 | 31篇 |
排序方式: 共有5623条查询结果,搜索用时 31 毫秒
171.
Philip J. Nickel 《Minds and Machines》2013,23(4):489-502
Some of the systems used in natural language generation (NLG), a branch of applied computational linguistics, have the capacity to create or assemble somewhat original messages adapted to new contexts. In this paper, taking Bernard Williams’ account of assertion by machines as a starting point, I argue that NLG systems meet the criteria for being speech actants to a substantial degree. They are capable of authoring original messages, and can even simulate illocutionary force and speaker meaning. Background intelligence embedded in their datasets enhances these speech capacities. Although there is an open question about who is ultimately responsible for their speech, if anybody, we can settle this question by using the notion of proxy speech, in which responsibility for artificial speech acts is assigned legally or conventionally to an entity separate from the speech actant. 相似文献
172.
Zoe R. Howard Corliss A. O'Bryan Philip G. Crandall Steven C. Ricke 《Food research international (Ottawa, Ont.)》2012,45(2):755-764
Foodborne illness caused by Salmonella spp. is a worldwide problem. In the United States Salmonella Enteritidis is the second most commonly isolated serotype from human illness, and is known to be strongly associated with shell eggs and egg containing products. Eggs can become contaminated internally either by penetration through the shell or directly during formation in the reproductive tract. This review begins with a brief account of the physiology of egg production and the various physical and chemical barriers the egg possesses to prevent bacterial contamination. Factors involved in vertical and horizontal transmission of S. Enteritidis are examined, as well as the role of forced molt in colonization of the hen. Pre- and post-harvest mitigation strategies are also discussed. 相似文献
173.
174.
175.
A planar antenna array that includes 12 corrugated tapered slot elements for use in ultrawideband (UWB) biomedical microwave imaging systems is presented. The used corrugate tapered slot antenna has a compact size, low profile, moderate gain, and distortionless performance in the time domain. The array is immersed in a carefully designed matching liquid of suitable dielectric constant to improve the matching between the array and the imaged object, and thus, to increase the dynamic range of the imaging system. A suitable platform is designed and fabricated to accommodate the array, breast phantom, and a coupling liquid for the case of UWB breast imaging. The design of the whole system is optimized using trust‐region framework method in the simulation tool CST Microwave Studio. The performance of the designed array is confirmed via measurements in a realistic imaging environment. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
176.
Thomas R. Bieler Scott C. Sutton Bret E. Dunlap Zackery A. Keith Philip Eisenlohr Martin A. Crimp Brad L. Boyce 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(1):121-128
The evolution of heterogeneous deformation in a tantalum polycrystal was examined during a three-point bending experiment using electron backscatter pattern mapping. Slip bands formed at strains as low as 1%, and they became more intense with strain. Heterogeneous deformation was evident as intragranular orientation gradients as large as 30° were observed after a strain of about 8%. Nonmonotonic changes in the local average misorientation distribution were observed, implying that dislocation substructure developed in a complex manner. Slip bands were analyzed using plane traces computed from local orientation information. With the assumption of uniaxial stress, Schmid factors for favorable slip systems were identified for each grain and compared with observations, showing evidence for macroscopic activity on both {110} and {112} slip systems. Reconstructed boundary data were used to estimate the geometric potential for slip transfer at grain boundaries. The correlations indicated that when active slip systems were favorably oriented for slip transfer across the boundary, it was often observed in the form of continuous slip bands aligned across the boundary. In boundaries where geometrical alignment and Schmid factors were not favorable for slip transfer, there was a higher likelihood to form ledges (topographic discontinuities) along the grain boundaries. Dislocation pileups at grain boundaries were also correlated with a low potential for slip transfer. 相似文献
177.
178.
Bibliometric analysis of publication metadata is an important tool for investigating emerging fields of technology. However, the application of field definitions to define an emerging technology is complicated by ongoing and at times rapid change in the underlying technology itself. There is limited prior work on adapting the bibliometric definitions of emerging technologies as these technologies change over time. The paper addresses this gap. We draw on the example of the modular keyword nanotechnology search strategy developed at Georgia Institute of Technology in 2006. This search approach has seen extensive use in analyzing emerging trends in nanotechnology research and innovation. Yet with the growth of the nanotechnology field, novel materials, particles, technologies, and tools have appeared. We report on the process and results of reviewing and updating this nanotechnology search strategy. By employing structured text-mining software to profile keyword terms, and by soliciting input from domain experts, we identify new nanotechnology-related keywords. We retroactively apply the revised evolutionary lexical query to 20 years of publication data and analyze the results. Our findings indicate that the updated search approach offers an incremental improvement over the original strategy in terms of recall and precision. Additionally, the updated strategy reveals the importance for nanotechnology of several emerging cited-subject categories, particularly in the biomedical sciences, suggesting a further extension of the nanotechnology knowledge domain. The implications of the work for applying bibliometric definitions to emerging technologies are discussed. 相似文献
179.
180.