全文获取类型
收费全文 | 2008篇 |
免费 | 75篇 |
专业分类
电工技术 | 38篇 |
综合类 | 3篇 |
化学工业 | 393篇 |
金属工艺 | 22篇 |
机械仪表 | 34篇 |
建筑科学 | 76篇 |
矿业工程 | 4篇 |
能源动力 | 40篇 |
轻工业 | 150篇 |
水利工程 | 18篇 |
石油天然气 | 3篇 |
无线电 | 282篇 |
一般工业技术 | 319篇 |
冶金工业 | 230篇 |
原子能技术 | 18篇 |
自动化技术 | 453篇 |
出版年
2023年 | 10篇 |
2022年 | 16篇 |
2021年 | 32篇 |
2020年 | 17篇 |
2019年 | 28篇 |
2018年 | 33篇 |
2017年 | 45篇 |
2016年 | 43篇 |
2015年 | 44篇 |
2014年 | 66篇 |
2013年 | 109篇 |
2012年 | 98篇 |
2011年 | 111篇 |
2010年 | 91篇 |
2009年 | 100篇 |
2008年 | 113篇 |
2007年 | 83篇 |
2006年 | 96篇 |
2005年 | 83篇 |
2004年 | 78篇 |
2003年 | 75篇 |
2002年 | 54篇 |
2001年 | 32篇 |
2000年 | 30篇 |
1999年 | 39篇 |
1998年 | 52篇 |
1997年 | 29篇 |
1996年 | 41篇 |
1995年 | 24篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 22篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 20篇 |
1975年 | 12篇 |
1973年 | 13篇 |
排序方式: 共有2083条查询结果,搜索用时 15 毫秒
991.
Aurlie Guyomard Emmanuelle D Thierry Jouenne Jean‐Jacques Malandain Guy Muller Karine Glinel 《Advanced functional materials》2008,18(5):758-765
A non‐water‐soluble natural antibacterial peptide, gramicidin A, has been successfully incorporated into polyelectrolyte assemblies to elaborate biocidal thin films. For this, we used a double strategy, the first step of which consists of complexing the peptide by a non‐denaturing anionic amphiphilic polysaccharide, namely a hydrophobically modified carboxymethylpullulan. We demonstrate that the use of this amphiphilic anionic derivative allows to efficiently solubilize the peptide in aqueous solution, without denaturation. The amount of peptide solubilized by the amphiphilic polysaccharide was optimized by systematically varying the hydrophobicity and the molar mass of the CMP derivative. In a second step, the negatively charged complex was layer‐by‐layer assembled with cationic poly(L‐lysine) to form biofunctionalized thin films. The amount of peptide incorporated in the multilayers was controlled by changing the number of deposited complex layers, and was quantified by UV spectroscopy. The antibacterial activity of the resulting biofunctionalized films was evidenced against a gram‐positive bacterium, E. faecalis. We demonstrated that the biocidal activity resulted from a double mechanism: contact between bacteria and the film surface, and release of the peptide into the solution surrounding the film. We also showed that the peptide was not completely removed from the film after rinsing, which insured preservation of the biocidal activity of the film surface. 相似文献
992.
Christopher Brouse Guy A Dumont Felix J Herrmann J Mark Ansermino 《IEEE engineering in medicine and biology magazine》2006,25(4):76-82
A software approach has been developed for detecting electrocautery noise in the electrocardiogram (ECG) using a wavelet decomposition of the signal. With this approach, a clinical monitoring expert system can be forewarned of potential artifacts in trend values derived from the ECG, allowing it to proceed with caution when making decisions based on these trends. In 15 operations spanning 38.5 h of ECG data, we achieved a false positive rate of 0.71% and a false negative rate of 0.33%. While existing hardware approaches detect the source of the noise without any ability to assess its impact on the measured ECG, our software approach detects the presence of noise in the signal itself. Furthermore, the software approach is cheaper and easier to implement in a clinical environment than existing hardware approaches. 相似文献
993.
994.
995.
996.
Given a set of timetabled tasks, the multi-depot vehicle scheduling problem consists of determining least-cost schedules for
vehicles assigned to several depots such that each task is accomplished exactly once by a vehicle. In this paper, we propose
to compare the performance of five different heuristics for this well-known problem, namely, a truncated branch-and-cut method,
a Lagrangian heuristic, a truncated column generation method, a large neighborhood search heuristic using truncated column
generation for neighborhood evaluation, and a tabu search heuristic. The first three methods are adaptations of existing methods,
while the last two are new in the context of this problem. Computational results on randomly generated instances show that
the column generation heuristic performs the best when enough computational time is available and stability is required, while
the large neighborhood search method is the best alternative when looking for good quality solutions in relatively fast computational
times. 相似文献
997.
Brady Joan Laidig; Guy James D.; Poelstra Paul L.; Brokaw Beth Fletcher 《Canadian Metallurgical Quarterly》1999,30(4):386
Should psychotherapists limit their clinical work with trauma survivors to avoid being traumatized themselves? Vicarious traumatization (VT—the symptoms similar to posttraumatic stress disorder and the disruption in cognitive schemas reported in clinicians who are exposed to the trauma material of their clients—was assessed in a national survey of 1,000 women psychotherapists. Therapists with higher levels of exposure to sexual abuse material reported significantly more trauma symptoms but no significant disruption of cognitive schemas. Spiritual well-being, a key area thought to be damaged by VT, was found to be higher for those clinicians who saw more sexual abuse survivors. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
998.
The authors report on a technique for the treatment of symptomatic, chronic complete dislocations of the acromioclavicular joint. The coracoacromial ligament is substituted for the coracoclavicular ligaments, and a special temporary coracoclavicular lag screw is used to stabilize the clavicle to the coracoid during ligament healing. The technique has been used on 23 patients who were observed for an average of 5.2 years. Good to excellent results were obtained in 19 of 23 patients. The four patients with fair or poor results had one or more resections of the distal clavicle before the reconstruction. Subjectively, 22 of 23 patients reported improvement in their shoulder. 相似文献
999.
High-inversion densities in Nd:YAG-upconversion and bleaching 总被引:1,自引:0,他引:1
Guy S. Bonner C.L. Shepherd D.P. Hanna D.C. Tropper A.C. Ferrand B. 《Quantum Electronics, IEEE Journal of》1998,34(5):900-909
We report on the investigation of upconversion in Nd:YAG and its implications for intensely pumped devices. Analysis of lifetime measurements and the performance of a 1 at.% Nd-doped YAG amplifier give an Auger upconversion rate of 7×103 s-1. This is significantly smaller than previously reported, but modeling of the performance of Nd:YAG devices with high-inversion densities shows that even this rate can still seriously degrade the small-signal gain and significantly increase the thermal load. The variation of cross-relaxation and upconversion rates with doping level is also described. Finally, it is found that the effect of bleaching of the Nd:YAG absorption can lead to a reduced spatial overlap between the signal and inversion profiles and thus can also significantly reduce the gain 相似文献
1000.
Jean-Marie Chapp Nicolas Martin Guy Terwagne Jan Lintymer Joseph Gavoille Jamal Takadoum 《Thin solid films》2003,440(1-2):66-73
Thin films of titanium oxynitride were successfully prepared by dc reactive magnetron sputtering using a titanium metallic target, argon, nitrogen and water vapour as reactive gases. The nitrogen partial pressure was kept constant during every deposition whereas that of the water vapour was systematically changed from 0 to 0.1 Pa. The evolution of the deposition rate with an increasing amount of water vapour injected into the process was correlated with the target poisoning phenomenon estimated from the target potential. Structure and morphology of the films were analysed by X-ray diffraction and scanning electron microscopy. Films were poorly crystallised or amorphous with a typical columnar microstructure. Nitrogen, oxygen and titanium concentrations were determined by Rutherford backscattering spectroscopy and nuclear reaction analysis, and the amount of hydrogen in the films was also quantified. Optical transmittance in the visible region and electrical conductivity measured against temperature were gradually modified from metallic to semiconducting behaviour with an increasing supply of the water vapour partial pressure. Moreover, an interesting maximum of the electrical conductivity was observed in this transition, for a small amount of water vapour. 相似文献