全文获取类型
收费全文 | 1337篇 |
免费 | 62篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 24篇 |
综合类 | 3篇 |
化学工业 | 284篇 |
金属工艺 | 83篇 |
机械仪表 | 62篇 |
建筑科学 | 15篇 |
矿业工程 | 1篇 |
能源动力 | 50篇 |
轻工业 | 72篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 145篇 |
一般工业技术 | 369篇 |
冶金工业 | 92篇 |
原子能技术 | 13篇 |
自动化技术 | 184篇 |
出版年
2024年 | 1篇 |
2023年 | 28篇 |
2022年 | 37篇 |
2021年 | 42篇 |
2020年 | 30篇 |
2019年 | 31篇 |
2018年 | 50篇 |
2017年 | 52篇 |
2016年 | 60篇 |
2015年 | 43篇 |
2014年 | 62篇 |
2013年 | 101篇 |
2012年 | 68篇 |
2011年 | 90篇 |
2010年 | 61篇 |
2009年 | 62篇 |
2008年 | 56篇 |
2007年 | 50篇 |
2006年 | 26篇 |
2005年 | 32篇 |
2004年 | 23篇 |
2003年 | 33篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 37篇 |
1997年 | 28篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 19篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1405条查询结果,搜索用时 15 毫秒
81.
Brajesh Kumar Kaushik Sankar Sarkar Rajendra Prasad Agarwal R.C. Joshi 《Microelectronics Journal》2010,41(2-3):85-92
This paper deals with waveform analysis, crosstalk peak and delay estimation of CMOS gate driven capacitively and inductively coupled interconnects. Simultaneously switching inputs for the coupled interconnects are considered. A transmission line-based coupled model of interconnect is used for analysis. Alpha-power Law model of MOS transistor is used to represent the transistors in CMOS driver. Peaks and delays at far-end of victim line are estimated for conditions when the inputs to the two coupled interconnects are switching in-phase and out-of-phase. The comparison of analytically obtained results with SPICE simulations show that the proposed model captures noise peak and their timing; 90% propagation delay; transition time delay and waveform shape with good accuracy, such as not more than 5% error in crosstalk peak estimation. 相似文献
82.
Nina Orlovskaya Sergey Yarmolenko Jag Sankar Jakob Kuebler Mykola Lugovy 《Journal of Materials Science》2008,43(17):5942-5947
A study of hot pressed B4C-based laminates, after rolling and without rolling, has been performed to elucidate the existence of fracture resistance/crack
length anisotropy induced by this processing technique. While the crack lengths/fracture resistance was affected significantly
by the presence of the residual stresses in B4C/B4C–ZrB2 laminates, no differences in Vickers crack lengths were observed in B4C/B4C laminates prepared by rolling and hot pressing, as compared to the crack lengths seen in pure B4C ceramics prepared by hot pressing without rolling. X-ray diffraction analysis confirmed that no texture has been formed
during the rolling and hot pressing of B4C ceramics. 相似文献
83.
Structural studies on an inhibitory antibody against Thermus aquaticus DNA polymerase suggest mode of inhibition 总被引:1,自引:0,他引:1
Murali R; Helmer-Citterich M; Sharkey DJ; Scalice ER; Daiss JL; Sullivan MA; Krishna Murthy HM 《Protein engineering, design & selection : PEDS》1998,11(2):79-86
TP7, an antibody against Thermus aquaticus DNA polymerase I (TaqP), is used
as a thermolabile switch in 'hot start' variations of PCR to minimize
non-specific amplification events. Earlier studies have established that
TP7 binds to the polymerase domain of TaqP, competes with primer template
complex for binding and is a potent inhibitor of the polymerase activity of
TaqP. We report crystallographic determination of the structure of an Fab
fragment of TP7 and computational docking of the structure with the known
three-dimensional structure of the enzyme. Our observations strongly
suggest that the origin of inhibitory ability of TP7 is its binding to
enzyme residues involved in DNA binding and polymerization mechanism.
Although criteria unbiased by extant biochemical data have been used in
identification of a putative solution, the resulting complex offers an
eminently plausible structural explanation of biochemical observations. The
results presented are of general significance for interpretation of docking
experiments and in design of small molecular inhibitors of TaqP, that are
not structurally similar to substrates, for use in PCR. Structural and
functional similarities noted among DNA polymerases, and the fact that
several DNA polymerases are pharmacological targets, make discovery of
non-substrate based inhibitors of additional importance.
相似文献
84.
Wu A.T. Murali V. Nulman J. Triplett B. Fraser D.B. Garner M. 《Electron Device Letters, IEEE》1989,10(10):443-445
The gate bias polarity dependence of charge trapping and time-dependent dielectric breakdown (TDDB) in nitrided and reoxidized nitrided silicon dioxides prepared by rapid thermal processing (RTP) is reported. Charge trapping during high-field injection can be reduced by rapid thermal nitridation for both substrate and gate injection. While reoxidation of nitrided oxides shows further reduction in charge trapping for substrate injection, degradation is observed for gate injection. Similar effects are observed for TDDB: reoxidized nitrided oxides show charge-to-breakdown in excess of 300 C/cm2 for substrate injection, but less than 30 C/cm2 for gate injection. These effects are related to the nitrogen and hydrogen profiles in the oxides. By tailoring the process conditions, a symmetric behavior of NO and RONO films with low charge trappings and Q BD in excess of 50 C/cm2 is possible, making them attractive as long-lifetime dielectrics from EEPROM (electrically erasable programmable ROM) and flash EEPROM technologies 相似文献
85.
Jiaze Li Smriti Murali Krishna Jonathan Golledge 《International journal of molecular sciences》2016,17(8)
Abdominal aortic aneurysm (AAA) is a vascular condition that causes permanent dilation of the abdominal aorta, which can lead to death due to aortic rupture. The only treatment for AAA is surgical repair, and there is no current drug treatment for AAA. Aortic inflammation, vascular smooth muscle cell apoptosis, angiogenesis, oxidative stress and vascular remodeling are implicated in AAA pathogenesis. Kallistatin is a serine proteinase inhibitor, which has been shown to have a variety of functions, potentially relevant in AAA pathogenesis. Kallistatin has been reported to have inhibitory effects on tumor necrosis factor alpha (TNF-α) signaling induced oxidative stress and apoptosis. Kallistatin also inhibits vascular endothelial growth factor (VEGF) and Wnt canonical signaling, which promote inflammation, angiogenesis, and vascular remodeling in various pre-clinical experimental models. This review explores the potential protective role of kallistatin in AAA pathogenesis. 相似文献
86.
Selecting a threshold from the gradient histogram, a histogram of gradient magnitudes, of an image plays a crucial role in a gradient based edge detection system. This paper presents a methodology to determine the threshold from a gradient histogram generated using any kind of linear gradient operator on an image. We consider the image as a random process with dependent samples, model the gradient histogram using theories of random process and random input to a system, and determine a region of interest in the gradient histogram using certain properties of a probability density function. Standard histogram thresholding techniques are then used within the region of interest to get the threshold value. To obtain the edges, this threshold value is then used as the upper threshold of the hysteresis thresholding technique that follows the non-maximum suppression operation applied on the gradient magnitude image. The proposed methodology of determining a threshold in a gradient histogram is deduced through rigorous analysis and hence it helps in achieving consistently appreciable edge detection performance. Experimental results using different real-life and benchmark images are shown to demonstrate the effectiveness of the proposed technique. 相似文献
87.
88.
Anil G. Khadakkar K. Ravi Sankar P. Rathinam R. Narayanan S. P. Rao J. K. Popli 《Strain》1997,33(2):57-60
This paper describes an experimental investigation carried out involving instrumentation, measurement and monitoring of stresses in a large diameter gas pipeline during its lowering operations. It also highlights the ingenious techniques developed and adopted to overcome the difficulties pertaining to long leadwires, measurement of existing strains on the curved surface of a pipeline and protection of strain gauge installations. These novel methods were used to ensure smooth and proper functioning of strain gauge instrumentation even under the severe field conditions at site for more than two weeks, till the lowering operations and pipeline monitoring was successfully completed. 相似文献
89.
K.H. Sabeena Farvin S. Hari Senthil KumarR. Anandan Suseela MathewT.V. Sankar P.G. Viswanathan Nair 《Food chemistry》2007,105(4):1390-1395
We have investigated the preventive effects of squalene against isoprenaline-induced myocardial infarction in male albino rats. Supplementation with squalene significantly prevented the isoprenaline-induced adverse changes in the levels of protein and glycoprotein components in plasma and heart tissue of experimental groups of rats. It exerted an antioxidant effect by inhibiting the isoprenaline-induced lipid peroxidation and by maintaining the level of non-enzymatic free radical-scavenger, reduced glutathione at near normalcy. Histopathological observations also confirmed the possible cardioprotective action of squalene by maintaining the normal architecture of the heart tissue. The results of the present investigation demonstrate that supplementation with squalene offers cardioprotection in experimental rats by its antioxidant and membrane- stabilizing properties. 相似文献
90.
K.R. Murali 《Materials Science in Semiconductor Processing》2010,13(3):193-198
CdSexTe1?x films were deposited by the slurry coating technique using CdSexTe1?x powders synthesized in the laboratory. X-ray diffraction studies indicated the formation of a hexagonal phase. From EDAX compositional analysis, the individual concentrations of Se and Te in the films were estimated. Analysis of the optical data indicate the band gap to vary from 1.44 to 1.68 eV as the value of ‘x’ changes from 0 to 1. XPS analysis was also carried out on the films. The films were used as photoanodes in polysulphide electrolyte and it was observed that the films with composition CdSe0.6Te0.4 exhibited the maximum photoactivity. The Mott–Schottky plot indicated an n-type behaviour. Spectral response measurements were made and the electrodes exhibited a quantum efficiency of 0.6. 相似文献