全文获取类型
收费全文 | 1418篇 |
免费 | 36篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 15篇 |
综合类 | 9篇 |
化学工业 | 178篇 |
金属工艺 | 114篇 |
机械仪表 | 33篇 |
建筑科学 | 63篇 |
矿业工程 | 9篇 |
能源动力 | 17篇 |
轻工业 | 147篇 |
水利工程 | 4篇 |
石油天然气 | 8篇 |
无线电 | 159篇 |
一般工业技术 | 216篇 |
冶金工业 | 199篇 |
原子能技术 | 6篇 |
自动化技术 | 280篇 |
出版年
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 35篇 |
2013年 | 79篇 |
2012年 | 53篇 |
2011年 | 79篇 |
2010年 | 65篇 |
2009年 | 75篇 |
2008年 | 87篇 |
2007年 | 81篇 |
2006年 | 79篇 |
2005年 | 79篇 |
2004年 | 54篇 |
2003年 | 67篇 |
2002年 | 57篇 |
2001年 | 28篇 |
2000年 | 25篇 |
1999年 | 31篇 |
1998年 | 29篇 |
1997年 | 29篇 |
1996年 | 37篇 |
1995年 | 40篇 |
1994年 | 21篇 |
1993年 | 24篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1970年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有1457条查询结果,搜索用时 15 毫秒
61.
Diffusion Tensor Imaging (DTI) has made feasible the visualization of the fibrous structure of the brain white matter. In the last decades, several fiber‐tracking methods have been developed to reconstruct the fiber tracts from DTI data. Usually these fiber tracts are shown individually based on some selection criteria like region of interest. However, if the white matter as a whole is being visualized clutter is generated by directly rendering the individual fiber tracts. Often users are actually interested in fiber bundles, anatomically meaningful entities that abstract from the fibers they contain. Several clustering techniques have been developed that try to group the fiber tracts in fiber bundles. However, even if clustering succeeds, the complex nature of white matter still makes it difficult to investigate. In this paper, we propose the use of illustration techniques to ease the exploration of white matter clusters. We create a technique to visualize an individual cluster as a whole. The amount of fibers visualized for the cluster is reduced to just a few hint lines, and silhouette and contours are used to improve the definition of the cluster borders. Multiple clusters can be easily visualized by a combination of the single cluster visualizations. Focus+context concepts are used to extend the multiple‐cluster renderings. Exploded views ease the exploration of the focus cluster while keeping the context clusters in an abstract form. Real‐time results are achieved by the GPU implementation of the presented techniques. 相似文献
62.
Prof. Dr. Hans Ulrich Buhl Dr. Bernd Heinrich Prof. Dr. Peter Loos Prof. Dr. Ulrich Frank Visiting Prof. Daniel L. Moody PhD Prof. Jeffrey Parsons PhD Prof. Dr. Michael Rosemann Prof. Dr. Elmar J. Sinz Prof. Ron Weber PhD Achim Kindler Dr. Prof. Dr. Claus Rautenstrauch Dipl.-Wirt.-Inf. Peter Fettke 《WIRTSCHAFTSINFORMATIK》2005,47(2):152-161
63.
This paper presents an integrated framework for describing and implementing quality of network (QoN) concepts. It focuses on identifying a systems engineering framework for better understanding how to specify and implement QoN concepts. We demonstrate, by means of several examples, that the quality of service interfaces between the end user and the underlying network are very important. Finally, we provide insights as to future development efforts needed to realize the goal of high quality networks. 相似文献
64.
Biological applications of near-field optical microscopy 总被引:1,自引:0,他引:1
Presents several biological applications of near field optical microscopy, in combination with force microscopy. Aperture near field scanning optical microscopy (NSOM) with fluorescence detection gives (bio)chemical specificity and orientational information, in addition to the simultaneously acquired force image. This technique has large potential for DNA sequencing, molecular organization in monolayers, and study of the role of the cytoskeleton in cellular mobility in cell growth, cell migration, formation of protrusions, etc. Fluorescence NSOM gives high resolution on flat, not too deep surfaces. Fluorescence NSOM induces virtually no bleaching, as opposed to confocal fluorescence microscopy. Bright field NSOM in transmission generally yields a complicated contrast, caused by a mixture of dielectric and topographic contributions. Shear force feedback is essential in aperture NSOM operation with fibers, and operates on soft surfaces of cells and chromosomes. Ultimately, aperture NSOM is limited by low efficiency with a source brightness of typically 100 pW to 10 nW. Thus, in spectroscopic applications (fluorescence, Raman, etc.) photon noise will be a fundamental limit in the speed of imaging. Photon tunneling in combination with force microscopy allows routine scanning with a high optical lateral resolution. However, interference effects can be dominant on surfaces which display extensive scattering. As such, the application potential of PSTM to biological surfaces is rather limited. Clearly, the virtues of optics, non-invasiveness, high spectral resolution, and high time resolution all apply to the near field optical domain with its high spatial resolution, which adds extensively to the potential of scanning probe microscopy 相似文献
65.
A system that contrasts driver behaviour with normative behaviour was tested in an advanced driving simulator. Drivers were provided with auditory and visual tutoring messages if deviations were detected from normative, i.e. legally allowed behaviour with respect to a selection of offences. Results showed that the system was very effective in increasing law-abiding behaviour, which has a major positive effect on traffic safety. However, driver mental effort, as indicated by self-reports and drivers' physiological states, was slightly increased in conditions where drivers received feedback. Opinion about the tutoring system was positive in terms of usefulness. Self-reports on satisfaction differed between age groups; young drivers rated it low, while elderly drivers held a positive attitude. 相似文献
66.
B Modan E Ron L Lerner-Geva T Blumstein J Menczer J Rabinovici G Oelsner L Freedman S Mashiach B Lunenfeld 《Canadian Metallurgical Quarterly》1998,147(11):1038-1042
Among 2,496 infertile Israeli women treated between 1964 and 1974, 143 cancer cases were observed as compared with 116.1 expected (standardized incidence ratio (SIR) = 1.2, 95% confidence interval (CI) 1.0-1.5) through 1991. Site-specific analysis revealed 12 ovarian cancers versus 7.2 expected (SIR = 1.6, 95% CI 0.8-2.9), 21 endometrial cancers versus 4.3 expected (SIR = 4.85, 95% CI 3.0-7.4), and 59 breast cancers versus 46.6 expected (SIR = 1.3, 95% CI 0.96-1.6). Sensitivity analysis revealed that confounding was unlikely to explain the raised risk of endometrial cancer, but nulliparity might explain the increased risk of ovarian cancer. The excess of endometrial cancer was prominent among patients with normal estrogen production but progesterone deficiency (SIR = 9.4, 95% CI 5.0-16.0). The risk for ovarian cancer was similar among the total groups of treated and untreated patients (SIR = 1.7 vs. 1.6). The standardized incidence ratio for endometrial cancer was higher among the treated group than the untreated group, although not significantly. Treatment with ovulation-inducing drugs does not appear to increase the risk for ovarian cancer, but its role cannot be completely excluded. 相似文献
67.
Ron Steinfeld Yuliang Zheng 《Applicable Algebra in Engineering, Communication and Computing》2004,15(3-4):179-200
We investigate the security of a variant of the RSA public-key cryptosystem called LSBS-RSA, in which the modulus primes share a large number of least-significant bits. We show that low public-exponent LSBS-RSA is inherently resistant to Partial Key Exposure (PKE) attacks in which least-significant bits of the secret exponent are revealed to the attacker, and in particular that the Boneh-Durfee-Frankel PKE attack [5] on low public-exponent RSA is less effective for LSBS-RSA systems than for standard RSA. On the other hand, we show that large public-exponent LSBS-RSA is more vulnerable to such attacks than standard RSA. An application to server-aided RSA signature generation is proposed.This is an extended version of an earlier paper presented at the Cryptographers Track RSA Conference (CT-RSA 2001), April 8-12 2001, San Francisco, USA [20].This work was done while the author was at the School of Network Computing, Monash University, Frankston, Australia.Acknowledgement The authors would like to thank the anonymous referees of CT-RSA 2001 for their helpful comments on a preliminary version [20] of some of the results in this paper. 相似文献
68.
High-spatial resolution mass spectrometric imaging of peptide and protein distributions on a surface
For the first time macromolecular ion microscope images have been recorded using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Single-shot, mass-resolved images of the spatial distributions of intact peptide and protein ions over an area of 200 microm in diameter were obtained in less than 1 ms at a repetition rate of 12 Hz. The magnifying ion optics of the ion microscope allowed ion images to be obtained with a lateral resolution of 4 microm. These results prove the concept of high-resolution MALDI-MS imaging in microscope mode without the need for a tight laser focus and the accompanying sensitivity losses. The ion microscopy approach offers an improvement of several orders of magnitude in speed of acquisition compared to the conventional (microprobe) approach to MALDI-MS imaging. 相似文献
69.
McDonnell LA Mize TH Luxembourg SL Koster S Eijkel GB Verpoorte E de Rooij NF Heeren RM 《Analytical chemistry》2003,75(17):4373-4381
It is well known in secondary ion mass spectrometry (SIMS) that sample topography leads to decreased mass resolution. Specifically, the ion's time of flight is dependent on where it was generated. Here, using matrix-enhanced SIMS, it is demonstrated that, in addition to increasing the yield of intact pseudomolecular ions, the matrix allows the user to semiquantitatively record the topography of a sample. Through mapping the topography-related mass shifts of the matrix (which leads to decreased mass resolution), the analogous mass shifts of higher mass ions can be deconvoluted and higher resolution and greater sensitivity obtained. Furthermore, the semiquantitative topographical map obtained can be compared with any chemical images obtained, allowing the user to quickly ascertain whether local intensity maximums are due to topological features or represent genuine features of interest. 相似文献
70.
Given a function f over n binary variables, and an ordering of the n variables, we consider the Expected Decision Depth problem. Namely, what is the expected number of bits that need to be observed until the value of the function is determined, when bits of the input are observed according to the given order. Our main finding is that this problem is (essentially) #P-complete. Moreover, the hardness holds even when the function f is represented as a decision tree. 相似文献