全文获取类型
收费全文 | 2220篇 |
免费 | 63篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 46篇 |
综合类 | 1篇 |
化学工业 | 348篇 |
金属工艺 | 47篇 |
机械仪表 | 50篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 72篇 |
轻工业 | 61篇 |
水利工程 | 3篇 |
无线电 | 530篇 |
一般工业技术 | 501篇 |
冶金工业 | 168篇 |
原子能技术 | 16篇 |
自动化技术 | 414篇 |
出版年
2023年 | 7篇 |
2022年 | 24篇 |
2021年 | 38篇 |
2020年 | 23篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 28篇 |
2016年 | 48篇 |
2015年 | 35篇 |
2014年 | 75篇 |
2013年 | 195篇 |
2012年 | 127篇 |
2011年 | 137篇 |
2010年 | 105篇 |
2009年 | 109篇 |
2008年 | 142篇 |
2007年 | 89篇 |
2006年 | 86篇 |
2005年 | 81篇 |
2004年 | 77篇 |
2003年 | 72篇 |
2002年 | 59篇 |
2001年 | 59篇 |
2000年 | 51篇 |
1999年 | 63篇 |
1998年 | 84篇 |
1997年 | 61篇 |
1996年 | 69篇 |
1995年 | 34篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 23篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有2290条查询结果,搜索用时 46 毫秒
151.
Stress Power Dependent Self-Heating Degradation of Metal-Induced Laterally Crystallized n-Type Polycrystalline Silicon Thin-Film Transistors 总被引:2,自引:0,他引:2
Hsing-Huang Tseng Tobin P.J. Kalpat S. Schaeffer J.K. Ramon M.E. Fonseca L.R.C. Jiang Z.X. Hegde R.I. Triyoso D.H. Semavedam S. 《Electron Devices, IEEE Transactions on》2007,54(12):3276-3284
Using a fluorinated high-k/metal gate stack combined with a stress relieved preoxide (SRPO) pretreatment before high-k deposition, we show significant device reliability and performance improvements. This is a critical result since threshold voltage instability may be a fundamental problem, and performance degradation for high-fc is a concern. The novel fluorinated TainfinCy/HfZrOinfin/SRPO gate stack device exceeds the positive-bias-temperature-instability and negative-bias-temperature-instability targets with sufficient margin and has electron mobility at 1 MV/cm comparable to the industrial high-quality polySi/SiON device on bulk silicon. 相似文献
152.
Optical networks with DWDM (Dense Wavelength Division Multiplex) can provide multiple data channels to supply high speed,
high capacity to perform bandwidth-intensive multicast transmission service. Light-tree is a popular technique applied to
support point-to-multipoint multicast services. Any failure during a multicast session would cause severe service loss or
disruptions, especially when the faults occur near the source node. A novel ring-based local fault recovery mechanism, Multiple
Ring-based Local Restoration (MRLR), for point-to-multipoint multicast traffic based on the minimum spanning tree (MST) in
WDM mesh networks is proposed in this article. The MRLR mechanism dismembers the multicast tree into several disjoint segment-blocks
(sub-trees) and reserves preplanned spare capacity to set up multiple protection rings in each segment-block for providing
rapid local recovery. The MRLR scheme outperforms other methodologies in terms of the blocking probability, recovery time,
and average hop count of protection path per session for different network topologies. 相似文献
153.
Rung-Chuang Feng Kuan-Jui Tseng Hsiu-Fang Yan Hsiu-Ya Huang Polun Chang 《Computer methods and programs in biomedicine》2013
This study analyzed and organized the content coverage of the clinical care classification (CCC) system to represent nursing record data in a medical center in Taiwan. The nursing care plan was analyzed using the process of knowledge discovery in the data set. The nursing documentation was mapped based on the full list of nursing diagnoses and interventions available using the CCC system. The result showed that 75.45% of the documented diagnosis terms can be mapped using the CCC system. A total of 21 established nursing diagnoses were recommended for inclusion in the CCC system. The results also showed that 30.72% of assessment/monitor tasks and 31.16% of care/perform tasks were provided by nursing professionals, whereas manage/refer actions accounted for 15.36% of the tasks involved in nursing care. The results showed that the CCC system is a suitable clinical information system for the majority of nursing care documentation, and is useful for determining the patterns in nursing practices. 相似文献
154.
Jingtong Hu Chun Jason Xue Meikang Qiu Wei-Che Tseng Edwin Hsing-Mean Sha 《Journal of Signal Processing Systems》2013,71(2):143-157
In Wireless Sensor Networks, the preloaded program code and data on sensor nodes often need to be updated due to changes in user requirements and environmental conditions. Sensor nodes are severely restricted by energy constraints. It is especially energy consuming for sensor nodes to transfer data through wireless radios. To efficiently reprogram sensor nodes through radio, we propose an algorithm, Minimum Data transferred by Copying and Downloading (MDCD) and its extension E-MDCD, to minimize the number of bytes needed to be transferred from the host machine to the sensor nodes. Experimental results show that the E-MDCD algorithm reduces the number of bytes transferred by 93.25 % for small code change compared with the Rsync based algorithm. In average, E-MDCD can reduce 59.82 % compared with the existing the Rsync based algorithm and 16.14 % compared with the Vdelta algorithm. 相似文献
155.
156.
Tsung-Hsien Tsai Tzung-Hsun Tsai Wen-Huey Wu Jonathon Te-Peng Tseng Po-Jung Tsai 《Food chemistry》2010
Propionibacterium acnes play an important role in the pathogenesis of acne by inducing certain inflammatory mediators and comedogenesis. The objective of this study was to evaluate the antimicrobial and anti-inflammatory effects of herbal extracts against P. acnes. Among the ten tested herbs, methanolic extracts of rose (Rosa damascene), duzhong (Eucommia ulmoides Oliv.), and yerba mate (Ilex paraguariensis) were found to inhibit the growth of P. acnes with respective minimum inhibitory concentrations of 2, 0.5, and 1 mg/ml. In addition, duzhong and yerba mate extracts reduced the secretion of pro-inflammatory cytokines such as tumour necrosis factor-α, interleukin (IL)-8, and IL-1β by human monocytic THP-1 cells pretreated with heat-killed P. acnes at a concentration of 0.1 mg/ml. Our results suggested that duzhong and yerba mate extracts possess both antimicrobial and anti-inflammatory effects against P. acnes and can possibly be used as therapeutic agents for acne. 相似文献
157.
King-Jet Tseng Shuyu Cao Jijiu Wang 《Industrial Electronics, IEEE Transactions on》2000,47(6):1228-1236
This paper presents an experimentally verified single-pulse-operation switched reluctance motor converter topology based on the basic buck-fronted topology and the modified C-dump topology. Using only (n+1) power switches, this topology is able to achieve full single-pulse operation, thereby reducing switching losses and acoustic noise. It also achieves a greater demagnetizing voltage compared to the basic buck-fronted topology, without having to increase the DC-source voltage. The converter is more robust as its dump capacitor stops being charged if the chopper switch fails. The principle of operation, modes of operation, transient simulation results, and experimental results are presented. 相似文献
158.
By using fiber gratings as pump reflectors with various reflectivities or N pieces of gain fibers with various lengths externally to linear cavity as self-equalizers, a parallel-type, pump-shared linear cavity laser array (LCLA) is proposed and numerically studied. The average output power is increased and the maximum power variation among channels is reduced from 7.2 to less than 0.1 dB when the reflectivity of each pump reflector or the length of each gain fiber is adjusted appropriately 相似文献
159.
Adequate cooling of the roll and strip is of considerable importance for mill designers, process engineers, and consumers. The purpose of this paper is to review recent heat-transfer research of the cooling technology in the steel-rolling process. The importance of roll and strip cooling on the thermomechanical treatment will be discussed with an assessment of the research on the corresponding heat-transfer coefficients for various cooling systems currently used. Special laboratory apparatus resembling the cooling system used in steel mills has been developed to study the major parameters that control the cooling processes. Since the heat-transfer coefficient is the most important indicator of the effectiveness of a cooling system, the coefficient under various roll-cooling conditions is experimentally studied by the special apparatus and numerically evaluated by a finite difference technique. 相似文献
160.
Linearity and power characteristics of SiGe HBTs at high temperatures for RF applications 总被引:2,自引:0,他引:2
Kun-Ming Chen An-Sam Peng Guo-Wei Huang Han-Yu Chen Sheng-Yi Huang Chun-Yen Chang Hua-Chou Tseng Tsun-Lai Hsu Liang V. 《Electron Devices, IEEE Transactions on》2005,52(7):1452-1458
In this paper, the power gain, power-added efficiency (PAE) and linearity of power SiGe heterojunction-bipolar transistors at various temperatures have been presented. The power characteristics were measured using a two-tone load-pull system. For transistors biased with fixed base voltage, the small-signal power gain and PAE of the devices increase with increasing temperature at low base voltages, while they decrease at high base voltages. Besides, the linearity is improved at high temperature for all voltage biases. However, for devices with fixed collector current, the small-signal power gain, PAE, and linearity are nearly unchanged with temperature. The temperature dependence of power and linearity characteristics can be understood by analyzing the cutoff frequency, the collector current, Kirk effect and nonlinearities of transconductance at different temperatures. 相似文献