全文获取类型
收费全文 | 2346篇 |
免费 | 171篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 1055篇 |
金属工艺 | 21篇 |
机械仪表 | 41篇 |
建筑科学 | 77篇 |
矿业工程 | 5篇 |
能源动力 | 41篇 |
轻工业 | 565篇 |
水利工程 | 15篇 |
石油天然气 | 7篇 |
无线电 | 80篇 |
一般工业技术 | 293篇 |
冶金工业 | 69篇 |
原子能技术 | 6篇 |
自动化技术 | 236篇 |
出版年
2024年 | 5篇 |
2023年 | 48篇 |
2022年 | 276篇 |
2021年 | 306篇 |
2020年 | 84篇 |
2019年 | 70篇 |
2018年 | 88篇 |
2017年 | 84篇 |
2016年 | 98篇 |
2015年 | 75篇 |
2014年 | 95篇 |
2013年 | 157篇 |
2012年 | 137篇 |
2011年 | 163篇 |
2010年 | 109篇 |
2009年 | 117篇 |
2008年 | 92篇 |
2007年 | 92篇 |
2006年 | 76篇 |
2005年 | 62篇 |
2004年 | 54篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 6篇 |
1998年 | 18篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 13篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1932年 | 2篇 |
排序方式: 共有2518条查询结果,搜索用时 15 毫秒
71.
André Campaniço Dr. Marta P. Carrasco Dr. Mathew Njoroge Ronnett Seldon Prof. Kelly Chibale Dr. João Perdigão Prof. Isabel Portugal Prof. Digby F. Warner Prof. Rui Moreira Prof. Francisca Lopes 《ChemMedChem》2019,14(16):1537-1546
Herein we report the screening of a small library of aurones and their isosteric counterparts, azaaurones and N-acetylazaaurones, against Mycobacterium tuberculosis. Aurones were found to be inactive at 20 μm , whereas azaaurones and N-acetylazaaurones emerged as the most potent compounds, with nine derivatives displaying MIC99 values ranging from 0.4 to 2.0 μm . In addition, several N-acetylazaaurones were found to be active against multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical M. tuberculosis isolates. The antimycobacterial mechanism of action of these compounds remains to be determined; however, a preliminary mechanistic study confirmed that they do not inhibit the mycobacterial cytochrome bc1 complex. Additionally, microsomal metabolic stability and metabolite identification studies revealed that N-acetylazaaurones are deacetylated to their azaaurone counterparts. Overall, these results demonstrate that azaaurones and their N-acetyl counterparts represent a new entry in the toolbox of chemotypes capable of inhibiting M. tuberculosis growth. 相似文献
72.
73.
Improved photon management in a photoelectrochemical cell with Nd-modified TiO2 thin film photoanode
Anna Kot Dominik Dorosz Marta Radecka Katarzyna Zakrzewska 《International Journal of Hydrogen Energy》2021,46(22):12082-12094
Photon management involving particularly an up-conversion process is proposed as a relatively novel strategy for improving the efficiency of hydrogen generation in photoelectrochemical cells (PEC) with wide-band gap photoanodes. Optically active photoanode has been constructed by electrodeposition of titanium dioxide nanopowders containing Nd3+ ions, synthesized via a sol-gel method, onto ITO/TiO2(thin film) substrates. Thin films of TiO2 have been deposited by means of RF magnetron sputtering in an ultra-high-vacuum system. X-ray diffraction, scanning electron microscopy, UV-VIS-NIR spectrophotometry, and photoluminescence have been applied to assess the properties of photoanodes. In experiments involving photon-assisted water splitting, an external up-converter containing Yb3+/Er3+ rare-earth ions has been used. Photocurrent as a function of voltage (VB) under illumination with white light is relatively high (280 μA at VB = 0 V) for pure TiO2 thin films and it is not affected by the electrodeposition of TiO2:Nd3+ powders. NIR-driven up-conversion with laser excitation at λ = 980 nm has been found responsible for a 13-fold increase in photocurrent at VB = 0 V in the modified PEC configuration. 相似文献
74.
Ultrastructural and developmental toxicity of potato and tomato leaf extracts to beet armyworm,Spodoptera exigua (lepidoptera: noctuidae)
下载免费PDF全文
![点击此处可从《Microscopy research and technique》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zbigniew Adamski Katarzyna Radtke Agnieszka Kopiczko Szymon Chowański Paweł Marciniak Monika Szymczak Marta Spochacz Patrizia Falabella Filomena Lelario Laura Scrano Sabino A. Bufo 《Microscopy research and technique》2016,79(10):948-958
Beet Armyworm, Spodoptera exigua is a herbivorous moth and a serious pest of many economically important plants, which are used as food sources. Because of rigorous standards of food quality, usage of synthetic insecticides in crop protection, against pests, is limited. Solanaceae plant extracts may be a relatively cheap source of efficient natural insecticides that can limit usage of synthetic substances. Their biological activity is not fully known. In particular, ultrastructural studies, using transmission electron microscopy, are not usual. In the present article we describe the effects of sublethal concentrations of tomato and potato leaf extracts against S. exigua. Acute lethal effects were not observed. Both extracts exerted similar effects within midgut and fat body cells. Midgut cells were not significantly altered while fat body cells showed prominent swelling of nuclear envelope and endoplasmic reticulum, vacuolization of mitochondria and fusion of fat droplets. These changes were much more intensive within groups exposed to potato than tomato extracts at highest concentration at least. Light microscopy was used to observe and document developmental alterations of S. exigua exposed to potato and tomato leaf extracts. Potato leaf extracts significantly decreased hatching success and caused morphological malformations of imagoes. Among them, malformations of wings were the most prominent. Interestingly, these effects were not observed within populations exposed to tomato extracts at highest concentration at least. 相似文献
75.
76.
Development of a long‐life vacuum‐packaged ready‐to‐eat meat product based on a traditional Portuguese seasoned meat
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marta Laranjo Ana Gomes Maria Eduarda Potes Maria José Fernandes Maria João Fraqueza Miguel Elias 《International Journal of Food Science & Technology》2016,51(5):1150-1158
Carne do alguidar is a Portuguese traditional pork fried meat, usually manufactured for self‐consumption purposes. This study developed a ready‐to‐eat (RTE) meat product, to meet today's consumers’ convenience, manufactured at the industrial scale evaluating its quality and shelf life, assessing the effect of vacuum packaging and the use of an antioxidant (50 ppm BHT) to enhance oxidative stability. Physicochemical and microbiological parameters were assessed, and a sensory analysis was performed. Interestingly, no significant differences were recorded between control (non‐BHT) and antioxidant (BHT) samples. Microbiological counts remained at low levels throughout the storage period, ensuring the product's required microbiological quality. At later storage stages, higher values of thiobarbituric acid‐reactive substances arose and off flavours and aromas were perceived. Still, overall appreciation was not affected until 12 months of storage and a significant depreciation was perceived only after 15 months. Fibrousness and rising of off flavours were negatively correlated with overall appreciation. 相似文献
77.
Moshe Y. Vardi Thomas A. Henzinger Rajeev Alur Marta Kwiatkowska 《Formal Methods in System Design》2012,41(1):1-2
The 2011 CAV (Computer-Aided Verification) Award was presented on July 17, 2011 at the 23rd annual CAV conference in Snowbird, Utah to Thomas Ball and Sriram Rajamani of Microsoft Research for their contributions to software model checking, specifically the development of the SLAM/SDV software model checker, which successfully demonstrated computer-aided verification techniques on real programs. 相似文献
78.
Enrique Costa-Montenegro Ana Belén Barragáns-Martínez Marta Rey-López 《Expert systems with applications》2012,39(10):9367-9375
Users face the information overload problem when downloading applications in markets. This is mainly due to (i) the increasing unmanageable number of applications and (ii) the lack of an accurate and fine-grained categorization of the applications in the markets. To address this issue, we present an integrated solution which recommends to the users applications by considering a big amount of information: that is, according to their previously consumed applications, use pattern, tags used to annotate resources and history of ratings. We focus this paper on the service for monitoring users’ interaction. 相似文献
79.
Colour changes of a thermochromic liquid crystal (TLC) ink printed on a black substrate are clearly observed by the naked eye, and therefore it is reasonable to expect that every approach recommended for colour measurements of samples with solid colour would be appropriate. In addition, the published spectroscopic analyses of TLC inks do not provide any guidance or limitations for the measurement geometry. On the other hand, our study demonstrates that spectroscopic measurements of such samples are not so straightforward. When using the most simple and commonly used measurement equipment with a directional illumination and viewing approach, the temperature-dependent spectral features resolve in a narrow spectral region that gives only a small part of the colour play effect. Detection of the entire effect requires the use of integrating spheres, which spatially integrate the radiant flux reflected on a sample in any direction; better results are obtained by spheres of larger diameter. The comparision of spectroscopic and colorimetric results obtained when different measurement geometries are applied on the same sample may demonstrate certain properties of the liquid crystal material inside microcapsules and help in understanding some details of the optical properties of the ink layer. 相似文献
80.
Marek Choratzy ;Marta Majcher ;Katarzyna Fedyszyn Urbanowicz ;Jedrzej Gtasek ;Maciej Gawlikowicz ;Tomasz Duniec 《材料科学与工程:中英文B版...》2014,(12):376-384
The authors compared their earlier results of the tumor biopsies performed under computer tomography (CT) guidance against the results of their recently modified-combined method of visualization and measurement of lung tumor parameters by CT imaging followed by US guided biopsy. In 238 (6.36%) of 3,745 patients in CT examination, the lung tumor was located peripherally, and obtaining histopathological confirmation was crucial to start the proper treatment. The patients were divided into two groups, the division was based on the biopsy method. Within the first group in I 18 patients, parietal lung tumor was confirmed and CT guided biopsy was performed. Within the second group, parietal lung tumor was confirmed in 120 patients and combined method of CT pre- biopsy planning and US guided biopsy were used. Pre-biopsy planning was performed using CT, measurements such as depth and distance of the tumor were made, obtained data were then saved on CT image and patient's skin was marked. Then obtained results were analyzed using test for two proportions. The analysis of the results confirmed the higher efficacy of the combined method taking into account the number of complications (p 〈 0.01) and diagnostic histopathological results (P 〈 0.001). Suggested innovative method, involving both CT pre-biopsy planning and US guided biopsy, allows to analyze simultaneously static CT and dynamic US images and it is considered to be an easy and effective method comparing to relying on static in nature CT images only. Our method is related to a lower complication risk rate. 相似文献