全文获取类型
收费全文 | 2023篇 |
免费 | 94篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 391篇 |
金属工艺 | 15篇 |
机械仪表 | 16篇 |
建筑科学 | 90篇 |
矿业工程 | 1篇 |
能源动力 | 26篇 |
轻工业 | 334篇 |
水利工程 | 19篇 |
石油天然气 | 4篇 |
无线电 | 104篇 |
一般工业技术 | 325篇 |
冶金工业 | 563篇 |
原子能技术 | 5篇 |
自动化技术 | 214篇 |
出版年
2023年 | 23篇 |
2022年 | 41篇 |
2021年 | 72篇 |
2020年 | 44篇 |
2019年 | 47篇 |
2018年 | 46篇 |
2017年 | 47篇 |
2016年 | 41篇 |
2015年 | 56篇 |
2014年 | 64篇 |
2013年 | 85篇 |
2012年 | 84篇 |
2011年 | 132篇 |
2010年 | 90篇 |
2009年 | 91篇 |
2008年 | 117篇 |
2007年 | 126篇 |
2006年 | 106篇 |
2005年 | 96篇 |
2004年 | 91篇 |
2003年 | 68篇 |
2002年 | 56篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 32篇 |
1998年 | 59篇 |
1997年 | 39篇 |
1996年 | 53篇 |
1995年 | 31篇 |
1994年 | 31篇 |
1993年 | 27篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1942年 | 6篇 |
排序方式: 共有2120条查询结果,搜索用时 585 毫秒
991.
People were trained to decode noise-vocoded speech by hearing monosyllabic stimuli in distorted and unaltered forms. When later presented with different stimuli, listeners were able to successfully generalize their experience. However, generalization was modulated by the degree to which testing stimuli resembled training stimuli: Testing stimuli's consonants were easier to recognize when they had occurred in the same position at training, or flanked by the same vowel, than when they did not. Furthermore, greater generalization occurred when listeners had been trained on existing words than on nonsense strings. We propose that the process by which adult listeners learn to interpret distorted speech is akin to building phonological categories in one's native language, a process where categories and structure emerge from the words in the ambient language without completely abstracting from them. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
Teaching artistic skills to children presents a unique challenge: High-level creative and social elements of an artistic discipline are often the most engaging and the most likely to sustain student enthusiasm, but these skills rely on low-level sensorimotor capabilities, and in some cases rote knowledge, which are often tedious to develop. We hypothesize that computer-based learning can play a critical role in connecting “bottom-up” (sensorimotor-first) learning in the arts to “top-down” (creativity-first) learning, by employing machine learning and artificial intelligence techniques that can play the role of the sensorimotor expert. This approach allows learners to experience components of higher-level creativity and social interaction even before developing the prerequisite sensorimotor skills or academic knowledge. 相似文献
993.
Nancy Kutner Rebecca Zhang Kirsten Johansen Donald Bliwise 《Hemodialysis international. International Symposium on Home Hemodialysis》2013,17(2):223-229
Fragmented nocturnal sleep is commonly reported by patients undergoing daytime conventional hemodialysis (CHD) and may be associated with higher mortality risk. Subjective sleepiness during CHD is also frequently observed. We examined the association of reported sleep fragmentation and nocturnal and daytime (intradialytic) sleep durations with survival in a national cohort of 1440 CHD patients who were interviewed in 2005–2007 in a phone survey conducted by the US Renal Data System. Patient survival was followed through September 30, 2010 in the US Renal Data System. A total of 76% of patients reported that they typically dozed off or slept during their treatment, and intradialytic dozing was especially common among patients whose treatment shift started before 1000 hours. There was a trend for patients who reported dozing during CHD to report nocturnal sleep fragmentation (60.4% vs. 55.1%; P = 0.07). With adjustment for intradialytic sleep and other covariates, nocturnal sleep fragmentation was not associated with survival. Mortality risk was higher for patients who reported sleeping 9 or more hours/night compared with the referent category of nocturnal sleep equal to 6–7 hours (hazard ratio: 1.50 [95% confidence interval: 1.04–2.17]; P = 0.03). Continued investigation of the association of timing and duration of sleep with hemodialysis patient outcomes is warranted. 相似文献
994.
Francy DS Stelzer EA Bushon RN Brady AM Williston AG Riddell KR Borchardt MA Spencer SK Gellner TM 《Water research》2012,46(13):4164-4178
995.
996.
Fieselmann A Ganguly A Deuerling-Zheng Y Zellerhoff M Rohkohl C Boese J Hornegger J Fahrig R 《IEEE transactions on medical imaging》2012,31(4):892-906
Tissue perfusion measurement during catheter-guided stroke treatment in the interventional suite is currently not possible. In this work, we present a novel approach that uses a C-arm angiography system capable of computed tomography (CT)-like imaging (C-arm CT) for this purpose. With C-arm CT one reconstructed volume can be obtained every 4-6 s which makes it challenging to measure the flow of an injected contrast bolus. We have developed an interleaved scanning (IS) protocol that uses several scan sequences to increase temporal sampling. Using a dedicated 4-D reconstruction approach based on partial reconstruction interpolation (PRI) we can optimally process our data. We evaluated our combined approach (IS-PRI) with simulations and a study in five healthy pigs. In our simulations, the cerebral blood flow values (unit: ml/100 g/min) were 60 (healthy tissue) and 20 (pathological tissue). For one scan sequence the values were estimated with standard deviations of 14.3 and 2.9, respectively. For two interleaved sequences the standard deviations decreased to 3.6 and 1.5, respectively. We used perfusion CT to validate the in vivo results. With two interleaved sequences we achieved promising correlations ranging from r=0.63 to r=0.94. The results suggest that C-arm CT tissue perfusion imaging is feasible with two interleaved scan sequences. 相似文献
997.
Effect of oxygen on aroma volatiles and quality of fresh-cut cantaloupe and honeydew melons 总被引:1,自引:0,他引:1
Ana L. Amaro John C. Beaulieu Casey C. Grimm Rebecca E. Stein Domingos P.F. Almeida 《Food chemistry》2012
Cantaloupe and honeydew melon cultivars were processed and stored under a high oxygen passive modified atmosphere packaging (MAP) or reduced oxygen controlled atmosphere (CA; 5 kPa O2 + 10 kPa CO2 and balance N2) for 14 days at 5 °C. Atmosphere did not affect softening rate or soluble solids content and had a negligible effect on colour. Volatile compounds known as flavour-important in melons were extracted using stir bar sorptive extraction (SBSE) and quantified via GC–MS. Acetate esters increased more in MAP than in CA. Non-acetate esters increased markedly in both cultivars and storage types. Alcohols were more abundant in honeydew than in cantaloupe. Aldehydes decreased during storage in both cultivars and storage types. Lower O2 availability under CA conditions likely suppressed some of the esters relevant to the aroma of fresh-cut melon. Results suggest that package O2 levels are more important in determining aroma than other quality attributes of fresh-cut melon, and high O2 levels may be required to reveal desirable aroma compounds. 相似文献
998.
A compact time-resolved system for near infrared spectroscopy based on wavelength space multiplexing
Re R Contini D Caffini M Cubeddu R Spinelli L Torricelli A 《The Review of scientific instruments》2010,81(11):113101
We designed and developed a compact dual-wavelength and dual-channel time-resolved system for near-infrared spectroscopy studies of muscle and brain. The system employs pulsed diode lasers as sources, compact photomultipliers, and time-correlated single photon counting boards for detection. To exploit the full temporal and dynamic range of the acquisition technique, we implemented an approach based on wavelength space multiplexing: laser pulses at the two wavelengths are alternatively injected into the two channels by means of an optical 2×2 switch. In each detection line (i.e., in each temporal window), the distribution of photon time-of-flights at one wavelength is acquired. The proposed approach increases the signal-to-noise ratio and avoids wavelength cross-talk with respect to the typical approach based on time multiplexing. The instrument was characterized on tissue phantoms to assess its properties in terms of linearity, stability, noise, and reproducibility. Finally, it was successfully tested in preliminary in vivo measurements on muscle during standard cuff occlusion and on the brain during a motor cortex response due to hand movements. 相似文献
999.
1000.
G Barreto-Torres R Parodi-Rullán S Javadov 《International journal of molecular sciences》2012,13(6):7694-7709
Metformin, an anti-diabetic drug, exerts cardioprotection against ischemia-reperfusion (IR) through the activation of AMPK. However, the molecular mechanisms underlying these beneficial effects remain elusive. In this study, we examined the role of PPARα in mediating cardioprotective effects of metformin on mitochondria. Hearts of male Sprague-Dawley rats perfused by Langendorff were subjected to IR in the presence or absence of metformin and the PPARβ inhibitor, GW6471. IR reduced cardiac function and compromised the structural integrity of cardiac cells evidenced by increased LDH release from the hearts. In addition, IR induced mitochondrial dysfunction as evidenced by reduced respiration and increased mitochondrial permeability transition pore (PTP) opening. However, metformin-treated hearts demonstrated improved post-ischemic recovery of cardiac function and reduced cell death that were associated with increased state 3 respiration at complexes I and II (by 27% and 32%, respectively, both p < 0.05) and decreased PTP opening (by 27%, p < 0.05) compared to untreated hearts. The protective effects of metformin on cardiac function and mitochondria were blocked by GW6471. Thus, our results demonstrate that inhibition of PPARα attenuates the beneficial effects of metformin on mitochondria in acute IR. 相似文献