全文获取类型
收费全文 | 1537篇 |
免费 | 69篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 348篇 |
金属工艺 | 30篇 |
机械仪表 | 36篇 |
建筑科学 | 46篇 |
矿业工程 | 2篇 |
能源动力 | 99篇 |
轻工业 | 145篇 |
水利工程 | 29篇 |
石油天然气 | 9篇 |
无线电 | 185篇 |
一般工业技术 | 379篇 |
冶金工业 | 99篇 |
原子能技术 | 21篇 |
自动化技术 | 166篇 |
出版年
2023年 | 17篇 |
2022年 | 39篇 |
2021年 | 59篇 |
2020年 | 40篇 |
2019年 | 38篇 |
2018年 | 71篇 |
2017年 | 59篇 |
2016年 | 60篇 |
2015年 | 42篇 |
2014年 | 55篇 |
2013年 | 125篇 |
2012年 | 73篇 |
2011年 | 88篇 |
2010年 | 73篇 |
2009年 | 88篇 |
2008年 | 69篇 |
2007年 | 57篇 |
2006年 | 38篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 17篇 |
1984年 | 17篇 |
1983年 | 27篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1974年 | 8篇 |
排序方式: 共有1613条查询结果,搜索用时 0 毫秒
101.
S. Ashok K. Kain J. M. Tartaglia N. S. Stoloff 《Metallurgical and Materials Transactions A》1983,14(10):1997-2003
High cycle fatigue tests in vacuum have been performed on ordered (Fe, Co, Ni)3V alloys between 25 °C and 850 °C. Heat-to-heat variations in fatigue properties of a Co-16.5 wtpct Fe-25 pct alloy, LRO-1, appeared to be due to differing quantities of grain boundary precipitates. Modification of this alloy with 0.4 pct Ti, to produce an alloy designated LRO-23, reduced the density of grain boundary precipitates and increased ductility, resulting in superior fatigue strength at high temperatures. The fatigue lives of LRO-1 and LRO-23 decreased rapidly above 650 °C, and increased intergranular failure was noted. The fatigue resistance of a cobalt-free alloy, Fe-29 pct Ni-22 pct V-0.4 pct Ti (LRO-37), was examined at 25 °C, 400 °C, and 600 °C; there was little evidence for intergranular fracture at any of these temperatures. Fatigue behavior of the LRO alloys is compared to that of conventional high temperature alloys. 相似文献
102.
103.
The daily dietary intakes and total contents of Cs and I in skeletal muscle and thyroid, respectively, for an average Indian adult were estimated by determining their concentrations in the total cooked diet and tissue samples using instrumental neutron activation analysis. These data were then used to predict the biological half-lives of Cs and I and their radioactive counterparts for the Reference Indian Man. The predicted biological half-lives of Cs and I for Reference Indian Man were found to be comparable with the reported values for the ICRP Reference Man. 相似文献
104.
A new poly(vinylchloride) (PVC) membrane electrode for trace level determination of Co2+ ions has been developed based on 5-amino-3-methylisothiazole as an ionophore, o-nitrophenyloctylether as a plasticizer and oleic acid (OA) as a good lipophilic additive. The electrode exhibits a Nernstian slope of 29.5 ± 0.2 mV/decade in a linear range of 1.0 × 10−1 to 6.3 × 10−7 M for Co2+ ions. The detection limit of this electrode is 3.9 × 10−7 M. It has a fast response time of 12 s and can be used for a period of 4 months without any divergence in potentials. The proposed electrode reveals a good selectivity for Co (II) over a wide variety of other tested cations and could be used in the pH range 3.3–9.0. The electrode was successfully applied as an indicator electrode for the potentiometric titration of cobalt ions with EDTA as well as for the direct determination of Co (II) in real samples. 相似文献
105.
Tilke A. T. Stapelmann C. Eller M. Bach K.-H. Hampp R. Lindsay R. Conti R. Wille W. Jaiswal R. Galiano M. Jain A. 《Semiconductor Manufacturing, IEEE Transactions on》2007,20(2):59-67
In the present work, a high aspect ratio process (HARP) using a new O3/TEOS based sub atmospheric chemical vapor deposition process was implemented as STI gapfill in sub-65-nm CMOS. Good gapfill performance up to aspect ratios greater than 10:1 was demonstrated. Since the HARP process does not attack the STI liner as compared to HDP, a variety of different STI liners can be implemented. By comparing HARP with HDP, the geometry dependence of nand p-FET performance due to STI stress is discussed 相似文献
106.
107.
James R. Currie Ashok K. Batra Mohammad A. Alim Manmohan D. Aggarwal Ravindra B. Lal 《Journal of Materials Science: Materials in Electronics》2007,18(4):433-439
Polycrystalline SnO2 samples prepared in the laboratory were irradiated with 2 MeV He ions having doses of 3.62 × 1015 ion/cm2. The ac small-signal electrical data acquired for the polycrystalline SnO2 in the frequency (f) range 100 Hz ≤ f ≤ 1 MHz and temperature (T) range 26°C ≤ T ≤ 100°C revealed one semicircular relaxation in the impedance plane for the He implanted sample. However, two semicircular
relaxations were obtained in the same plane for the samples without He implantation. The He implantation indicated enhancement
in the donor density in the polycrystalline SnO2 as depicted via terminal conductance (or resistance).
An erratum to this article can be found at 相似文献
108.
Loc Tran Debrup Banerjee Jihong Wang Ashok J. Kumar Frederic McKenzie Yaohang Li Jiang Li 《Machine Vision and Applications》2013,24(5):995-1014
A novel manifold learning approach is presented to efficiently identify low-dimensional structures embedded in high-dimensional MRI data sets. These low-dimensional structures, known as manifolds, are used in this study for predicting brain tumor progression. The data sets consist of a series of high-dimensional MRI scans for four patients with tumor and progressed regions identified. We attempt to classify tumor, progressed and normal tissues in low-dimensional space. We also attempt to verify if a progression manifold exists—the bridge between tumor and normal manifolds. By identifying and mapping the bridge manifold back to MRI image space, this method has the potential to predict tumor progression. This could be greatly beneficial for patient management. Preliminary results have supported our hypothesis: normal and tumor manifolds are well separated in a low-dimensional space. Also, the progressed manifold is found to lie roughly between the normal and tumor manifolds. 相似文献
109.
Machine learning has emerged as an effective medical diagnostic support system. In a medical diagnosis problem, a set of features that are representative of all the variations of the disease are necessary. The objective of our work is to predict more accurately the presence of cardiovascular disease with reduced number of attributes. We investigate intelligent system to generate feature subset with improvement in diagnostic performance. Features ranked with distance measure are searched through forward inclusion, forward selection and backward elimination search techniques to find subset that gives improved classification result. We propose hybrid forward selection technique for cardiovascular disease diagnosis. Our experiment demonstrates that this approach finds smaller subsets and increases the accuracy of diagnosis compared to forward inclusion and back-elimination techniques. 相似文献
110.
Microstructure and abrasive wear study of (Ti,W)C-reinforced high-manganese austenitic steel matrix composite 总被引:2,自引:0,他引:2
Ashok Kumar Srivastava 《Materials Letters》2008,62(24):3947-3950
A high-manganese austenitic steel matrix composite (Fe-1.42%C-16.02%Mn-0.447%Si-0.288%Al-0.34%Cr-0.028%S-0.25%P-3.02%Ti-3.0%W, all in wt.%) reinforced with in-situ (Ti,W)C was synthesized by conventional melting and casting route. It has been found that the concentration of Ti decreases whereas the concentration of tungsten increases from core to the periphery of the (Ti,W)C particulates. The abrasive wear resistance of as-cast (Ti,W)C-reinforced composite is better than that of the as-cast high-manganese austenitic steel matrix material. 相似文献