全文获取类型
收费全文 | 35351篇 |
免费 | 2610篇 |
国内免费 | 1349篇 |
专业分类
电工技术 | 1740篇 |
技术理论 | 2篇 |
综合类 | 2199篇 |
化学工业 | 6122篇 |
金属工艺 | 2007篇 |
机械仪表 | 1970篇 |
建筑科学 | 2564篇 |
矿业工程 | 1033篇 |
能源动力 | 862篇 |
轻工业 | 1901篇 |
水利工程 | 519篇 |
石油天然气 | 2556篇 |
武器工业 | 229篇 |
无线电 | 4003篇 |
一般工业技术 | 4128篇 |
冶金工业 | 2706篇 |
原子能技术 | 427篇 |
自动化技术 | 4342篇 |
出版年
2024年 | 162篇 |
2023年 | 576篇 |
2022年 | 973篇 |
2021年 | 1395篇 |
2020年 | 1058篇 |
2019年 | 881篇 |
2018年 | 1039篇 |
2017年 | 1148篇 |
2016年 | 958篇 |
2015年 | 1259篇 |
2014年 | 1617篇 |
2013年 | 2008篇 |
2012年 | 2087篇 |
2011年 | 2328篇 |
2010年 | 1967篇 |
2009年 | 1802篇 |
2008年 | 1732篇 |
2007年 | 1622篇 |
2006年 | 1790篇 |
2005年 | 1621篇 |
2004年 | 1102篇 |
2003年 | 933篇 |
2002年 | 864篇 |
2001年 | 747篇 |
2000年 | 862篇 |
1999年 | 1051篇 |
1998年 | 1099篇 |
1997年 | 885篇 |
1996年 | 810篇 |
1995年 | 646篇 |
1994年 | 520篇 |
1993年 | 413篇 |
1992年 | 268篇 |
1991年 | 205篇 |
1990年 | 163篇 |
1989年 | 141篇 |
1988年 | 131篇 |
1987年 | 90篇 |
1986年 | 63篇 |
1985年 | 39篇 |
1984年 | 18篇 |
1983年 | 22篇 |
1982年 | 36篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 46篇 |
1976年 | 76篇 |
1975年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
1.
通过密度测定和DSC热分析,观测了超高分子量聚乙烯的辐射效应。实验结果表明:在吸收剂量0—1.13MGy范围内,密度随吸收剂量的增加而增大,熔化热和熔点也有所增加,特别是在低剂量范围内增加十分明显。以上结果都说明,超高分子量聚乙烯在辐照过程中,结晶在完善或有新的结晶形成 相似文献
2.
A distributed problem solving system can be characterized as a group of individual cooperating agents running to solve common problems. As dynamic application domains continue to grow in scale and complexity, it becomes more difficult to control the purposeful behavior of agents, especially when unexpected events may occur. This article presents an information and knowledge exchange framework to support distributed problem solving. From the application viewpoint the article concentrates on the stock trading domain; however, many presented solutions can be extended to other dynamic domains. It addresses two important issues: how individual agents should be interconnected so that their resources are efficiently used and their goals accomplished effectively; and how information and knowledge transfer should take place among the agents to allow them to respond successfully to user requests and unexpected external situations. The article introduces an architecture, the MASST system architecture, which supports dynamic information and knowledge exchange among the cooperating agents. The architecture uses a dynamic blackboard as an interagent communication paradigm to facilitate factual data, business rule, and command exchange between cooperating MASST agents. The critical components of the MASST architecture have been implemented and tested in the stock trading domain, and have proven to be a viable solution for distributed problem solving based on cooperating agents 相似文献
3.
On the basis of the compensation of errors it is postulated that the most accurate correction may not always give the most accurate result for calorific value, and experimental evidence for this is presented. A new criterion is therefore suggested for judging the best (not necessarily the most accurate) cooling correction. Using this principle the cooling correction formula previously proposed is improved which results in higher accuracy whilst retaining the original simplicity. 相似文献
4.
The Jian kiln, located in present-day Jianyang county of Fujian province, mainly produced black-glazed tea bowls. Jian tea bowl was used as a utensil for tea tasting and was greatly appreciated by emperor Huizong of the Northern Song dynasty. The black glaze of Jian bowl was sometimes marked with streaks or spots, usually called “hare's fur” or “oil spot”, which are the crystalline markings of iron oxide precipitated during firing in the dragon kiln. In this study, black-glazed Jian bowl sherds excavated from the late Northern Song strata of Luhuaping and Daluhoumen Jian kiln sites were adopted as test samples. Based on the physico-chemical foundation for the formation of glaze microstructure, the correlation among composition, microstructure, and visual appearance has been investigated by means of energy-dispersive X-ray fluorescence, X-ray diffraction, and field emission electron microscopy. For the first time, the study provides realizing proofs for two kinds of microstructural forming mechanics. 相似文献
5.
Wei Li Zhang Wei Pan Bin Luo Xi Hua Zou Meng Yao Wang 《Photonics Technology Letters, IEEE》2008,20(9):712-714
A theoretical construction of one-to-many (OTM) and many-to-one (MTO) chaos synchronization communications using semiconductor lasers is presented. One center laser provides strong injections (strong link) to other side lasers, and the side lasers also provide weak injections (weak link) to the center one. Simulation results show that the side lasers synchronize with the center laser through injection-locking. In addition, messages transmitted via the strong links or the weak links experience strong chaos pass filtering, enabling us to realize OTM and MTO communications. 相似文献
6.
7.
The strengths of two graphite/epoxy notched laminate systems with a softening strip were investigated. The softening strip was created by replacing the 0°-graphite/epoxy plies by a glass/epoxy composite. Experimental results indicated that the use of softening strips could significantly increase the laminate strength. Analysis was performed with finite elements developed using the classical laminated plate theory and was shown to be adequate. A simple point-stress failure criterion was used to predict the strength of notched laminates with softening strips and the result was found to be satisfactory. 相似文献
8.
9.
Graham A. Jullien Wenzhe Luo Neil M. Wigley 《The Journal of VLSI Signal Processing》1996,14(2):207-220
This paper discusses strategies for implementing DSP systems using residue replication. The theory, recently introduced by two of the authors, uses formal polynomial ring mappings, from binary representations, to direct product ring implementation of integer processing arrays. The mapping produces completely independent computational arrays each computing over the same ring. This paper describes an architecture and processing array to implement, and take advantage of, the special computational ring structures that result from the mapping. A brief review of the theory and mapping techniques, is followed by the discussion of the architecture and VLSI design of an efficient inner product processing array using Fermat Primes. 相似文献
10.
本文报道从1984年6月1日至1985年5月31日对宝鸡市五县(区)医用诊断 X 线照射频度的调查结果。结果表明,胸透和群检胸透医照率最高,占医疗照射总人次数的68.7%,门诊医照率为70.8人次/千人·年,人群受照率为344。5人次/千人·年。按年龄比较,青壮年组医照率最高,占医照总人次数的57.2%。按性别比较,男性多于女性。 相似文献