全文获取类型
收费全文 | 925篇 |
免费 | 59篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 283篇 |
金属工艺 | 10篇 |
机械仪表 | 28篇 |
建筑科学 | 20篇 |
能源动力 | 25篇 |
轻工业 | 81篇 |
水利工程 | 10篇 |
石油天然气 | 3篇 |
无线电 | 100篇 |
一般工业技术 | 135篇 |
冶金工业 | 83篇 |
原子能技术 | 3篇 |
自动化技术 | 190篇 |
出版年
2023年 | 11篇 |
2022年 | 53篇 |
2021年 | 64篇 |
2020年 | 31篇 |
2019年 | 17篇 |
2018年 | 42篇 |
2017年 | 30篇 |
2016年 | 26篇 |
2015年 | 27篇 |
2014年 | 43篇 |
2013年 | 68篇 |
2012年 | 64篇 |
2011年 | 63篇 |
2010年 | 37篇 |
2009年 | 29篇 |
2008年 | 39篇 |
2007年 | 39篇 |
2006年 | 36篇 |
2005年 | 19篇 |
2004年 | 21篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1987年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1977年 | 8篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1961年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有986条查询结果,搜索用时 15 毫秒
81.
Maddi Salvatore R.; Khoshaba Deborah M.; Pammenter Arthur 《Canadian Metallurgical Quarterly》1999,51(2):117
Our turbulent times require organizations that are hardy in the sense of having cultures, climates, structures, and workforces capable of turning potentially disruptive changes into opportunities. At the individual, or workforce, level, hardiness involves the attitudes of commitment, control, and challenge and the complementary skills of coping and social support. At the organizational level, the isomorphic counterparts of hardy attitudes are the cultural values of cooperation, credibility, and creativity. Furthermore, an organization is hardy if these cultural values are indeed expressed on an everyday basis through its climate and if its structure involves the matrix management scheme of semi-autonomous work teams rather than the more traditional hierarchical arrangement. This article also considers the assessment and consulting functions that can increase the hardiness of organizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
Antonio Cataliotti Valentina Cosentino Alessandro Lipari Salvatore Nuccio Danilo Serazio 《Measurement》2013
This paper is focused on the use of data acquisition boards (DAQs) for the development of high accuracy PC-based instruments for the measurements of electrical power. The proposed systems are simple, portable and low cost because they are based on commercial data acquisition boards (DAQs) connected to a common personal computer. Data processing is carried out by a commercial software based on an interpolating windowed FFT. In the paper it is shown how the voltage can be sensed directly, thanks to the DAQ input range, thus avoiding expensive voltage dividers. The set up of the DAQs-based solutions is described and the evaluation of their metrological features is made by means of a comparison with the Italian power primary standard, which was built at INRIM with a complex solution and expensive with two high precision digital voltmeters. 相似文献
83.
The photolabile and phototoxic fluoroquinolone (FQ) antibacterial drugs norfloxacin and rufloxacin have been used as capping agents for 25 nm Ag nanoparticles, exploiting the noncovalent interaction between the cationic piperazinyl ring of both FQs and the negatively charged metal surface. The resulting FQ‐protected silver nanoclusters (Ag@FQs), ca. 80 nm in diameter, are dispersible in phosphate buffer at physiological pH and their response to light excitation has been studied by steady‐state and time‐resolved spectroscopic and photochemical techniques. The fluorescence emission of the FQs chromophores is not extensively quenched in the Ag@FQs. In contrast, both Ag@FQs exhibit a photochemical stability more than one order of magnitude larger than that of the free drugs. This is the result of significant and differentiated quenching effects by the Ag surface on the kinetic and population of the excited triplet states of FQs, which are the key intermediate in the drugs photodecomposition. In view of the well‐known antimicrobial properties of the Ag nanoparticles, the Ag@FQs could represent intriguing nanohybrids in the perspective multifunctional nanodrugs. 相似文献
84.
Isodiana Crupi Stefano Boscarino Giacomo Torrisi Giorgia Scapellato Salvatore Mirabella Giovanni Piccitto Francesca Simone Antonio Terrasi 《Nanoscale research letters》2013,8(1):392
Laser irradiation of ZnO:Al/Ag/ZnO:Al transparent contacts is investigated for segmentation purposes. The quality of the irradiated areas has been experimentally evaluated by separation resistance measurements, and the results are complemented with a thermal model used for numerical simulations of the laser process. The presence of the Ag interlayer plays two key effects on the laser scribing process by increasing the maximum temperature reached in the structure and accelerating the cool down process. These evidences can promote the use of ultra-thin ZnO:Al/Ag/ZnO:Al electrode in large-area products, such as for solar modules. 相似文献
85.
An Automated Tool for Smart Water Network Partitioning 总被引:1,自引:0,他引:1
Armando Di Nardo Michele Di Natale Giovanni Francesco Santonastaso Salvatore Venticinque 《Water Resources Management》2013,27(13):4493-4508
Water Network Partitioning (WNP) represents the application of the “divide and conquer” paradigm to a Smart WAter Network (SWAN) that allows the improved application of techniques for water balance and pressure control. Indeed, these techniques can be applied with greater effectiveness by defining smaller permanent network parts, called District Meter Areas (DMAs), created by the insertion of gate valves and flow meters. The traditional criteria for the design of network DMAs are based on empirical suggestions (number of properties, length of pipes, etc.) and on approaches such as ‘trial and error’, even if used together with hydraulic simulation software. Nevertheless, these indications and procedures are very difficult to apply to large water supply systems because the insertion of gate valves modifies the original network layout and may considerably worsen the hydraulic performance of the water network. The proposed tool, based on some graph partitioning techniques, commonly applied in distributed computing, and on an original optimisation technique, allows the automatic design of a WNP comparing different possible layouts that are compliant with hydraulic performance. In this paper, the methodology was tested on a real case study using some performance indices to compare different WNPs. The proposed tool was developed in Phyton and integrates graph partitioning, hydraulic simulation techniques and a heuristic optimisation criterion. It allows the definition of DMAs with resulting performance indices that are very similar to the original network layout. 相似文献
86.
In this paper, an approach useful for stochastic analysis of the Gaussian and non-Gaussian behavior of the response of multi-degree-of-freedom (MDOF) wind-excited structures is presented. This approach is based on a particular model of the multivariate stochastic wind field based upon a particular diagonalization of the power spectral density (PSD) matrix of the fluctuating part of wind velocity. This diagonalization is performed in the space of eigenvectors and eigenvalues that are called here wind-eigenvalues and wind-eigenvectors, respectively. From the examination of these quantities it can be recognized that the wind-eigenvectors change slowly with frequency while the first wind-eigenvalue dominates all the others in the low-frequency range. It is shown that the wind field can be modeled in a satisfactory way by taking the first wind-eigenvector as constant and by retaining only the first eigenvalue in the calculations. The described model is then used for stochastic analysis in the time domain of MDOF wind-excited structures. This is accomplished by modeling each element of the diagonalized wind-PSD matrix as the velocity PSD function of a set of second-order digital filters with viscous damping driven by white noise of selected intensity. This approach makes it easy to obtain in closed form the statistical moments of every order of the structural response, taking full advantage of the Itô calculus. Moreover, in the proposed approach, it is possible to reduce the computational effort by appropriately selecting the number of wind modes retained in the calculation. 相似文献
87.
G Lupoli E Cascone F Arlotta G Vitale L Celentano M Salvatore G Lombardi 《Canadian Metallurgical Quarterly》1996,78(5):1114-1118
BACKGROUND: The medical treatment of advanced medullary thyroid carcinoma (MTC) is still questionable. Results of chemotherapy are disappointing with almost no curative responses, few partial responses, and many side-effects. A recent report has suggested the activity of combination recombinant interferon alpha-2b (rIFN-alpha-2b) and octreotide, a somatostatin analogue, in the treatment of a metastatic carcinoid tumor. This new therapeutic schedule may be used in other neuroendocrine tumors. In this study we evaluated the therapeutic effectiveness of octreotide and rIFN-alpha-2b in patients with advanced MTC. METHODS: Eight patients affected by advanced MTC received octreotide at a daily dose of 150 micrograms for 6 months and subsequently at a daily dose of 300 micrograms for another 6 months, subcutaneously, and rIFN-alpha-2b at a daily dose of 5.000.000 IU intramuscularly 3 times a week for 12 months. Plasma calcitonin, carcinoembryonic antigenic levels, and morphologic staging were evaluated at 0, 1, 3, 6, and 12 months. RESULTS: The therapy was stopped in two patients because of diarrhea and toxicity of drugs used. Pre-existing diarrhea in four patients and flushing in one significantly improved during treatment. A maximum decrease of calcitonin was reached after 1 month in 2 patients and after 3 months in 4. In all of the patients carcinoembryonic antigen levels decreased during treatment. No significant changes of size of metastases were observed. CONCLUSIONS: The combination of octreotide and interferon is well tolerated and can be recommended for the treatment of advanced MTC. 相似文献
88.
A new scheme to alleviate contention in optical burst switching networks is proposed. It consists of preventively reserving resources in a node, to be used if resources are busy on the next hop node. The burst is sent back to the preceding node and then resent forward. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution based on deflection routing. 相似文献
89.
Lido Calorini Anna Fallani Donatella Tombaccini Emanuela Barletta Gabriele Mugnai Maria F. Di Renzo Paolo M. Comoglio Salvatore Ruggieri 《Lipids》1989,24(8):685-690
To determine whether a metastatic phenotype may be corelated with a characteristic lipid pattern, we compared the lipid composition
of low metastasizing Balb/c 3T3 cells transformed by the B77 strain of Rous sarcoma virus (B77-3T3 cells) with that of a subclone
isolated by growth in 0.6% agar, the B77-AA6 cells, which exhibit a high capacity for spontaneous metastasis. B77-3T3 cells
revealed characteristics in their lipid composition common to other systems of transformed cells, i.e., an accumulation of
ether-linked lipids, a reduction of the more complex gangliosides, an increase of oleic acid (18∶1) and a decrease of arachidonic
(20∶4) and C22 polyunsaturated fatty acids in phospholipids. High metastatic B77-AA6 cells showed: a) an even more marked
decrease of complex gangliosides; b) a more pronounced increase of 18∶1 and decrease of 20∶4 and 22 polyunsaturated fatty
acids in certain phospholipid classes; and c) a higher percentage of alkyl-acyl subfractions in both phosphatidylcholine and
phosphatidylethanolamine than B77-3T3 cells.
Comparing the data for other systems of metastatic cells with those of lipid studies of spontaneously metastasizing B77-AA6
cell system leads us to conclude that the metastatic phenotype is characterized by a change in ether-linked lipids, rather
than in fatty acids. 相似文献