全文获取类型
收费全文 | 8564篇 |
免费 | 564篇 |
国内免费 | 55篇 |
专业分类
电工技术 | 133篇 |
综合类 | 7篇 |
化学工业 | 1743篇 |
金属工艺 | 327篇 |
机械仪表 | 586篇 |
建筑科学 | 165篇 |
矿业工程 | 1篇 |
能源动力 | 371篇 |
轻工业 | 644篇 |
水利工程 | 30篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 1750篇 |
一般工业技术 | 1827篇 |
冶金工业 | 623篇 |
原子能技术 | 149篇 |
自动化技术 | 813篇 |
出版年
2024年 | 7篇 |
2023年 | 109篇 |
2022年 | 112篇 |
2021年 | 281篇 |
2020年 | 216篇 |
2019年 | 181篇 |
2018年 | 246篇 |
2017年 | 271篇 |
2016年 | 318篇 |
2015年 | 227篇 |
2014年 | 337篇 |
2013年 | 543篇 |
2012年 | 556篇 |
2011年 | 671篇 |
2010年 | 486篇 |
2009年 | 501篇 |
2008年 | 470篇 |
2007年 | 370篇 |
2006年 | 331篇 |
2005年 | 306篇 |
2004年 | 277篇 |
2003年 | 239篇 |
2002年 | 252篇 |
2001年 | 212篇 |
2000年 | 206篇 |
1999年 | 198篇 |
1998年 | 310篇 |
1997年 | 183篇 |
1996年 | 140篇 |
1995年 | 94篇 |
1994年 | 99篇 |
1993年 | 80篇 |
1992年 | 44篇 |
1991年 | 55篇 |
1990年 | 38篇 |
1989年 | 32篇 |
1988年 | 28篇 |
1987年 | 29篇 |
1986年 | 17篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1974年 | 5篇 |
排序方式: 共有9183条查询结果,搜索用时 15 毫秒
221.
Gihwan Cho 《Journal of Network and Systems Management》1998,6(1):31-50
Using the Internet as a foundation for wirelessnetworking, there is currently a great deal of interestin providing IP networking support for mobile hosts. Asa result of IPs reliance on the entire Internet address for host identification, most proposalsdepend on a default route through the mobile host's homeaddress, which makes for unnecessarily long routes. Thispaper introduces two concepts, localregion and patron service, based on thelocality features of host moving and calling patterns.It then shows how these concepts work together torealize a location management scheme for achievingoptimal routing for most traffic while restricting costlylocation propagation. The proposed scheme wasimplemented using a network simulator and evaluated fromrouting effectiveness point of view, as compared withits location overhead. 相似文献
222.
BK Park ES Cho JD Lee C Oh MS Lee SZ Kim SH Kim KW Cho 《Canadian Metallurgical Quarterly》1998,43(8):611-618
The effect of a naturally occurring plant phenolic constituent (the acylphloroglucinol derivative, jensenone, derived from Eucalyptus jensenii) on the food intake of two folivorous marsupials, the common ringtail (Pseudocheirus peregrinus) and the common brushtail possum (Trichosurus vulpecula) was studied. When fed diets containing varying concentrations of jensenone, both species regulated their intake of jensenone so as not to exceed a ceiling intake. This ceiling was about twice as high for common ringtails as for common brushtails from northern Australia. Southern populations of common ringtails showed greatly reduced capacities to tolerate jensenone. When common brushtails were injected (0.5 mg.kg-0.75 body mass) with ondansetron (a selective antagonist of serotonin 5HT3 receptors), they ate significantly more jensenone than animals injected with physiological saline. The same pattern was observed when common ringtails were fed diets containing both jensenone and ondansetron (0.0035 mg.g-1 wet mass of diet). Ondansetron injection had no effect on food intake when the food did not contain jensenone while the addition of higher doses of ondansetron to diets of common ringtails very slightly reduced food intakes of a non-jensenone diet. When common brushtails were given 50 mg of jensenone by gastric lavage, their average subsequent intake of dietary jensenone matched the difference between the daily threshold and the dose given, although the response of individuals was highly variable. Lavage with water alone had no effect on subsequent jensenone intake compared with the pre-dose period. We interpret these results as evidence that the antifeedant effects of jensenone and related compounds are partly mediated by serotonin action on 5HT3 receptors most likely via "nausea" to condition a food aversion. 相似文献
223.
The index inhomogeneity and the microstructure of ZrO(2) films prepared by Ar-ion-assisted deposition are investigated. The results show that as the Ar-ion momentum transferred to the growing film increases, the average refractive index increases, the vacuum-to-air spectral shift becomes almost zero, the sign of relative inhomogeneity transits from negative to positive, and the void fraction of the top layer next to air becomes smaller than that of the bottom one. These optical properties result from the improved packing density and denser outer region next to air. The Ar-ion bombardment also induces the changes in microstructure of ZrO(2) films, such as the preferential (111) orientation of cubic phase, increase in compressive stress, and reduction of surface roughness. 相似文献
224.
S. S. Cho B. S. Chun C. H. Won B. S. Lee H. K. Kim B. J. Song M. Ryu 《Advanced Performance Materials》1996,3(1):29-42
The Al-12Si-5Fe-3Cu-1Mg(wt%) alloy was rapidly solidified by centrifugal atomization. The microstructural characteristics of rapidly solidified powder and the microstructure changes with heat treatment were investigated in terms and related to powder size. The microstructures of the powder consisted of dendritic -Al, eutectic phase, Cu-rich phase, and needle-like intermetallic compounds. These phases were much finer than that of ingot cast structure and the size decreased with increasing cooling rate. The X-ray diffraction of the atomized powders revealed the presence of non-equilibrium 3-(AlFeSi) intermetallic phase. This phase appeared to transform to an equilibrium -(AlFeSi) phase by heating at temperatures above 470°C. The extruded rod which was hot extruded at 360°C with an extrusion ratio of 40:1 also revealed the presence of the -(AIFeSi) intermetallic phase. Using DSC, the exothermic peak due to precipitation from the supersaturated -Al matrix was observed in the range of 200–250°C during continuous heating of atomized powder, and the size of the peaks increased with decreasing powder size. 相似文献
225.
Hyunjin Lee Lei Jin Kiyeon Lee Socrates Demetriades Michael Moeng Sangyeun Cho 《Software》2010,40(3):239-258
Simulation is indispensable in computer architecture research. Researchers increasingly resort to detailed architecture simulators to identify performance bottlenecks, analyze interactions among different hardware and software components, and measure the impact of new design ideas on the system performance. However, the slow speed of conventional execution‐driven architecture simulators is a serious impediment to obtaining desirable research productivity. This paper describes a novel fast multicore processor architecture simulation framework called Two‐Phase Trace‐driven Simulation (TPTS), which splits detailed timing simulation into a trace generation phase and a trace simulation phase. Much of the simulation overhead caused by uninteresting architectural events is only incurred once during the cycle‐accurate simulation‐based trace generation phase and can be omitted in the repeated trace‐driven simulations. We report our experiences with tsim, an event‐driven multicore processor architecture simulator that models detailed memory hierarchy, interconnect, and coherence protocol based on the TPTS framework. By applying aggressive event filtering, tsim achieves an impressive simulation speed of 146 millions of simulated instructions per second, when running 16‐thread parallel applications. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
226.
Why would people use Short Message Service (SMS) to say something they would not say in person? There is a trend that SMS is becoming more and more popular because it facilitates more extended modes of communications. Using technology acceptance model, we hypothesize the attitude of SMS would be influenced by its perceived effectiveness for communications, perceived ease of use, and subjective norm. Besides the special aspects of communications, conflict avoidance and privacy protection will enforce the impact of perceived effectiveness of SMS for communication. We investigated 953 SMS users and the results support most of our hypotheses. Furthermore, our analyses also show there are differences between females and males on the influence mechanism behind their attitude towards SMS. 相似文献
227.
228.
A great deal of research indicates that the shared disks (SD) cluster is suitable to high performance transaction processing.
However, the aggregation of SD cluster with real-time processing has not been investigated. By adopting cluster technology,
the real-time services will be highly available and can exploit internode parallelism. In this paper, we consider buffer management
issues in a real-time SD cluster. We first propose a real-time buffer coherency algorithm that exploits inherent characteristics
of real-time applications and SD cluster. Then we extend traditional buffer replacement algorithms to the real-time SD cluster.
They emphasize specific attributes of buffer pages to capitalize locality of references, transaction deadline, and affinity-based
routing. We evaluate the performance of the proposed algorithms under a wide variety of transaction workloads and system configurations. 相似文献
229.
This paper proposed a hybrid genetic based functional link artificial neural network (HFLANN) with simultaneous optimization
of input features for the purpose of solving the problem of classification in data mining. The aim of the proposed approach
is to choose an optimal subset of input features using genetic algorithm by eliminating features with little or no predictive
information and increase the comprehensibility of resulting HFLANN. Using the functionally expanded of selected features,
HFLANN overcomes the nonlinearity nature of problems, which is commonly encountered in single-layer neural networks. The features
like simplicity of the architecture and low computational complexity of the network encourage us to use it in classification
task of data mining. Further, the issue of statistical tests for comparison of algorithms on multiple datasets, which is even
more essential to typical machine learning and data mining studies, has been all but ignored. In this work, we recommend a
set of simple, yet safe and robust parametric and nonparametric tests for statistical comparisons of HFLANN with FLANN and
RBF classifiers over multiple datasets by an extensive simulation studies. 相似文献
230.
Road sign recognition system remains a challenging part of designing an Intelligent Driving Support System. While there exist
many approaches to classify road signs, none have adopted an unsupervised approach. This paper proposes a way of Self-Organizing
feature mapping for recognizing a road sign. The emergent self-organizing map (ESOM) is employed for the feature mapping in
this study. It has the capability of visualizing the distance structures as well as the density structure of high-dimensional
data sets, in which the ESOM is suitable to detect non-trivial cluster structures. This paper discusses the usage of ESOM
for road sign detection and classification. The benchmarking against some other commonly used classifiers was performed. The
results demonstrate that the ESOM approach outperforms the others in conducting the same simulations of the road sign recognition.
We further demonstrate that the result obtained with ESOM is significantly more superior than traditional SOM which does not
take into the boundary effect like ESOM did. 相似文献