全文获取类型
收费全文 | 2810篇 |
免费 | 195篇 |
国内免费 | 64篇 |
专业分类
电工技术 | 16篇 |
综合类 | 4篇 |
化学工业 | 887篇 |
金属工艺 | 32篇 |
机械仪表 | 68篇 |
建筑科学 | 121篇 |
矿业工程 | 7篇 |
能源动力 | 52篇 |
轻工业 | 776篇 |
水利工程 | 25篇 |
石油天然气 | 20篇 |
无线电 | 119篇 |
一般工业技术 | 438篇 |
冶金工业 | 246篇 |
原子能技术 | 12篇 |
自动化技术 | 246篇 |
出版年
2024年 | 7篇 |
2023年 | 24篇 |
2022年 | 134篇 |
2021年 | 151篇 |
2020年 | 73篇 |
2019年 | 61篇 |
2018年 | 83篇 |
2017年 | 86篇 |
2016年 | 109篇 |
2015年 | 80篇 |
2014年 | 118篇 |
2013年 | 192篇 |
2012年 | 164篇 |
2011年 | 229篇 |
2010年 | 150篇 |
2009年 | 166篇 |
2008年 | 162篇 |
2007年 | 142篇 |
2006年 | 107篇 |
2005年 | 92篇 |
2004年 | 80篇 |
2003年 | 78篇 |
2002年 | 66篇 |
2001年 | 36篇 |
2000年 | 25篇 |
1999年 | 47篇 |
1998年 | 53篇 |
1997年 | 36篇 |
1996年 | 41篇 |
1995年 | 31篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 48篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
排序方式: 共有3069条查询结果,搜索用时 0 毫秒
51.
Salvi D Gorman J Arredondo MT Vera-Muñoz C Ottaviano M Salvi S 《Computer methods and programs in biomedicine》2012,107(1):45-52
Personalized health (p-health) systems can contribute significantly to the sustainability of healthcare systems, though their feasibility is yet to be proven. One of the problems related to their development is the lack of well-established development tools for this domain. As the p-health paradigm is focused on patient self-management, big challenges arise around the design and implementation of patient systems. This paper presents a reference platform created for the development of these applications, and shows the advantages of its adoption in a complex project dealing with cardio-vascular diseases. 相似文献
52.
Using [2+2] photocycloaddition of coumarin groups attached to the PMMA chain backbone, we can gradually transfer a semidilute copolymer solution to a uniform speckle-free gel. We reexamined the effects of concentration, crosslinking density, solvent quality on the controversial scaling exponent (αs) between the linewidth (Γs) of the slow mode and the scattering vector (q) during the sol-gel transition. Our results suggest that the slow mode is attributed to large thermally agitated density fluctuation and revealed that the variation of αs is due to the relative length of 1/q to the correlation length (ξ) of the density fluctuation; namely, if ξ>1/q, αs→3, while when ξ<1/q, αs→2. 相似文献
53.
Z. G. Huang Z. N. Guo X. Chen T. M. Yue S. To W. B. Lee 《Materials and Manufacturing Processes》2006,21(4):393-397
This article surveys the advances of molecular dynamics (MD) simulation in the research of ultrafine machining and related technologies. Modeling methods, including interatomic potentials and boundary conditions, are addressed. Algorithm strategies for MD simulations are discussed. By applying simulations with Tersoff potential, a case study of the material removal mechanism of the polishing based on coupling vibrations of liquid (PCVL) is presented. 相似文献
54.
Dania Esposito Andrea Margonelli Emanuela Pace Maria Teresa Giardi Cecilia Faraloni Giuseppe Torzillo Alba Zanini 《Microgravity science and technology》2006,18(3-4):215-218
Photosynthetic microorganisms are expected to be useful to maintain an oxygenic atmosphere and to provide biomass for astronauts in the International Space Station as well as in future long-term space flights. However, fluxes of complex ionizing radiation of various intensities and energies make space an extreme environment for the microorganisms, affecting their photosynthetic efficiency. To automatically monitor the photosynthetic Photosystem II (PSII) activity of microorganisms under space conditions an optical biosensor, which utilizes chlorophyll fluorescence as biological transduction system, was built; the PSII activity was monitored by the biosensor during balloon flights at stratospheric altitudes of about 40 km. The effect of space stress on quantum yield of PSII varied among the tested species depending on the growth light conditions at which they were exposed during the flights. 相似文献
55.
Four experiments examined children's ability to reason about the causal significance of the order in which 2 events occurred (the pressing of buttons on a mechanically operated box). In Study 1, 4-year-olds were unable to make the relevant inferences, whereas 5-year-olds were successful on one version of the task. In Study 2, 3-year-olds were successful on a simplified version of the task in which they were able to observe the events although not their consequences. Study 3 found that older children had difficulties with the original task even when provided with cues to attend to order information. However, 5-year-olds performed successfully in Study 4, in which the causally relevant event was made more salient. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
Margarita Mediavilla Juan-Carlos Fraile Ignacio J. Galindo M. Teresa González 《Journal of Intelligent and Robotic Systems》2003,38(1):85-104
Strategy-based path planning was introduced by the authors as a way to give robotic manipulators some sort of reactive behaviour in dynamic and unpredictable environments. This approach is based on making robots react to moving obstacles using a restricted subset of the configuration space, and on using an off-line pre-planning stage to choose the restricted subset. In this paper, strategy-based path planning is applied and explored, focusing our attention on the off-line stage. It is applied to the joint motion of two and three robots that perform pick and place tasks sharing common working areas. 相似文献
57.
This paper addresses the issue of improving the performance of memory management for real-time Java applications, building upon the real-time specification for Java (RTSJ) from the Real-Time Java Expert Group. In a first step, a collecting dynamic memory solution including both a real-time garbage collector and region-based memory management, is proposed. A thorough analysis of the parameters influencing the performance of write barriers in memory management, together with ways of improvement are then presented. Finally, the implementation of a memory management solution compliant with the RTSJ and integrating the proposed improvements is sketched. 相似文献
58.
Freitas SP Gonçalves TC Serrão JE Santos-Mallet JR 《Microscopy research and technique》2007,70(4):355-360
Male of Triatoma rubrofasciata has four elongated sac-like reproductive mesodermic accessory glands, lined by an inner single layer of secretory cells, with basal plasma membrane infolds and short apical microvilli, and externally enveloped by a thin visceral muscle layer. The secretory cells have a well-developed rough endoplasmic reticulum, Golgi complex, mitochondria, and secretory granules. In one day old adult the gland cells are poorly developed, presenting small, electron-transparent secretory granules scattered among the rough endoplasmatic reticulum, whereas in three days old adult these cells have the cisternae of the rough endoplasmatic reticulum varing size degree, filled with granular electrondense content. In five days old males the secretory granules increase in diameter, being released to the gland lumen. Therefore, there is an increase of the secretory activity according to male maturation. 相似文献
59.
Sara Oliveira Tamaeh Monteiro-Alfredo Rita Henriques Carlos Fontes Ribeiro Raquel Seia Teresa Cruz Clia Cabral Rosa Fernandes Ftima Piedade Maria Paula Robalo Paulo Matafome Snia Silva 《International journal of molecular sciences》2022,23(10)
Curcumin has been suggested as a promising treatment for metabolic diseases, but the high doses required limit its therapeutic use. In this study, a new curcuminoid is synthesised to increase curcumin anti-inflammatory and antioxidant potential and to achieve hypoglycaemic and protective vascular effects in type 2 diabetic rats in a lower dose. In vitro, the anti-inflammatory effect was determined through the Griess reaction, and the antioxidant activity through ABTS and TBARS assays. In vivo, Goto-Kakizaki rats were treated for 2 weeks with the equimolar dose of curcumin (40 mg/kg/day) or curcuminoid (52.4 mg/kg/day). Fasting glycaemia, insulin tolerance, plasma insulin, insulin signalling, serum FFA, endothelial function and several markers of oxidative stress were evaluated. Both compounds presented a significant anti-inflammatory effect. Moreover, the curcuminoid had a marked hypoglycaemic effect, accompanied by higher GLUT4 levels in adipose tissue. Both compounds increased NO-dependent vasorelaxation, but only the curcuminoid exacerbated the response to ascorbic acid, consistent with a higher decrease in vascular oxidative and nitrosative stress. SOD1 and GLO1 levels were increased in EAT and heart, respectively. Altogether, these data suggest that the curcuminoid developed here has more pronounced effects than curcumin in low doses, improving the oxidative stress, endothelial function and glycaemic profile in type 2 diabetes. 相似文献
60.
Vera Pavese Andrea Moglia Silvia Abb Anna Maria Milani Daniela Torello Marinoni Elena Corredoira Maria Teresa Martínez Roberto Botta 《International journal of molecular sciences》2022,23(10)
Castanea sativa is an important tree nut species worldwide, highly appreciated for its multifunctional role, in particular for timber and nut production. Nowadays, new strategies are needed to achieve plant resilience to diseases, climate change, higher yields, and nutritional quality. Among the new plant breeding techniques (NPBTs), the CRISPR/Cas9 system represents a powerful tool to improve plant breeding in a short time and inexpensive way. In addition, the CRISPR/Cas9 construct can be delivered into the cells in the form of ribonucleoproteins (RNPs), avoiding the integration of exogenous DNA (GMO-free) through protoplast technology that represents an interesting material for gene editing thanks to the highly permeable membrane to DNA. In the present study, we developed the first protoplast isolation protocol starting from European chestnut somatic embryos. The enzyme solution optimized for cell wall digestion contained 1% cellulase Onozuka R-10 and 0.5% macerozyme R-10. After incubation for 4 h at 25 °C in dark conditions, a yield of 4,500,000 protoplasts/mL was obtained (91% viable). The transfection capacity was evaluated using the GFP marker gene, and the percentage of transfected protoplasts was 51%, 72 h after the transfection event. The direct delivery of the purified RNP was then performed targeting the phytoene desaturase gene. Results revealed the expected target modification by the CRISPR/Cas9 RNP and the efficient protoplast editing. 相似文献