全文获取类型
收费全文 | 2740篇 |
免费 | 96篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 33篇 |
综合类 | 4篇 |
化学工业 | 508篇 |
金属工艺 | 46篇 |
机械仪表 | 52篇 |
建筑科学 | 93篇 |
矿业工程 | 6篇 |
能源动力 | 122篇 |
轻工业 | 635篇 |
水利工程 | 49篇 |
石油天然气 | 42篇 |
无线电 | 145篇 |
一般工业技术 | 349篇 |
冶金工业 | 212篇 |
原子能技术 | 20篇 |
自动化技术 | 523篇 |
出版年
2023年 | 23篇 |
2021年 | 60篇 |
2020年 | 26篇 |
2019年 | 36篇 |
2018年 | 38篇 |
2017年 | 66篇 |
2016年 | 80篇 |
2015年 | 76篇 |
2014年 | 110篇 |
2013年 | 237篇 |
2012年 | 87篇 |
2011年 | 86篇 |
2010年 | 79篇 |
2009年 | 103篇 |
2008年 | 70篇 |
2007年 | 101篇 |
2006年 | 90篇 |
2005年 | 68篇 |
2004年 | 70篇 |
2003年 | 73篇 |
2002年 | 78篇 |
2001年 | 50篇 |
2000年 | 44篇 |
1999年 | 44篇 |
1998年 | 117篇 |
1997年 | 61篇 |
1996年 | 42篇 |
1995年 | 26篇 |
1994年 | 37篇 |
1993年 | 43篇 |
1992年 | 27篇 |
1991年 | 22篇 |
1990年 | 32篇 |
1989年 | 24篇 |
1988年 | 22篇 |
1987年 | 32篇 |
1985年 | 26篇 |
1984年 | 36篇 |
1983年 | 27篇 |
1982年 | 30篇 |
1981年 | 24篇 |
1980年 | 25篇 |
1979年 | 24篇 |
1978年 | 34篇 |
1977年 | 30篇 |
1976年 | 39篇 |
1975年 | 45篇 |
1974年 | 32篇 |
1973年 | 30篇 |
1971年 | 24篇 |
排序方式: 共有2839条查询结果,搜索用时 203 毫秒
1.
2.
3.
Sathya Vanlin Kala Srikant Manas Bhupeshraj S Tamma Bheemarjuna Reddy 《Wireless Networks》2021,27(1):441-464
Wireless Networks - Femto Cells offer higher data rates to users within closed spaces. Dense deployment of small cells is a characteristic of pre-5G/LTE-Advanced Pro (LTE-A Pro) networks and is a... 相似文献
4.
Zhang Xi Wang Xianhai Zhao Hongke Ordóñez de Pablos Patricia Sun Yongqiang Xiong Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with... 相似文献
5.
Wahab Ali Khan Masood Sadiq Butt Imran Pasha Muhammad Saeed Iqra Yasmin Maratab Ali Muhammad Azam Muhammad Shahroz Khan 《Journal of texture studies》2020,51(6):955-967
Vitamin D lost its functionality during processing and storage, thus, encapsulation with proteins is desirable to preserve bioactivity. The aim of the current study was to develop encapsulated vitamin D fortified mayonnaise (VDFM) using whey protein isolates (WPI) and soy protein isolates (SPI) as encapsulating materials in three different formulations, that is, 10% WPI, 10% SPI, and 5/5% WPI/SPI. Increased shear stress decreased the apparent viscosity along with significant effects on the loss modulus of VDFM. WPI encapsulates showed better results as compared to SPI. WPI based VDFM (M1) depicted the best results in terms of size and dispersion uniformity of oil droplets. Hue angle and total change differed significantly among treatments. The highest value for overall acceptability was acquired by M3 (5:5%WPI:SPI-encapsulates) thus proceed for in vivo trials. Serum vitamin D level was significantly higher in the encapsulated VDFM rat group (58.14 ± 6.29 nmol/L) than the control (37.80 ± 4.98 nmol/L). Conclusively, WPI and SPI encapsulates have the potential to improve the stability and bioavailability of vitamin D. 相似文献
6.
7.
8.
《Food Control》2015
A telephone survey was carried out on 13,486 randomly selected households located in the Abruzzo region (central Italy). Three questionnaires were specifically designed in relation to three different groups of foods (Meat and meat products, Fishery products, Fruit and vegetables). Questions were mainly focused on the amount and number of purchases, type of retailer, and home food handling practices with respect to the week prior to the interview. Data were classified according to a multilingual thesaurus system (LanguaL). Results allowed to estimate domestic purchases (in kg) per capita for different food categories. The category “Red meat/Cattle” accounted for a large part of purchases in the “meat and meat products” group (10.9 kg per capita/year; 32.2% of purchases in the group) while the category “Fish or related organism/Fish” was the most purchased in the “fishery products” group (6.9 kg per capita/year; 63.3%). The aggregation of more detailed characteristics enabled the identification of popular categories of foods, such as “Red meat/Cattle/Divided into pieces” (25% of the “meat and meat products” group). Significant differences (p < 0.05) were found between the four different provinces (L'Aquila, Chieti, Pescara and Teramo) with respect to “Poultry/Chicken” and “Red meat/Cattle” categories. Householders were also asked about post-purchase food handling practices that might be hazardous to food safety. More than 20% of those surveyed stated that they thawed frozen meat at room temperature. The degree of doneness after cooking of different food categories was generally high: over 90% of products purchased in the majority of meat and fish categories were properly cooked. However a noticeable proportion of householders (about 15%) reported medium or rare cooking of “Red meat/Cattle” and “Red meat/Swine”. Differences (p < 0.05) were also found between consumers of different ages, with people over 65 years old being more prone to freeze meat and cook it thoroughly.The survey was carried out in a specific geographic area and on a statistically significant sample of households, thus allowing a collection of data on domestic habits relating to food purchases and home food handling practices. This information should be included in the framework of quantitative microbial risk assessment (QMRA) models as a measure of the actual exposure of consumers to pathogenic microorganism. The LanguaL system also proved to be a practical language-independent method useful not only to identify and describe food items but also to classify them according to specific food safety characteristics. 相似文献
9.
《Journal of the European Ceramic Society》2020,40(9):3423-3430
The electromagnetic properties and EMI shielding effectiveness of Cf/mullite composites via the spark plasma sintering were intensively investigated in the gigahertz range (8.2–12.4 GHz). Experimental results have revealed excellent electromagnetic properties and a high value of EMI shielding effectiveness (nearly 40 dB) for Cf/mullite composites with 1.65 vol% carbon fillers at thickness of 2 mm. We quantitatively characterize the contributions of microstructural features to overall EMI shielding effectiveness using a micromechanics-based homogenization model. The EMI shielding effectiveness enhances with respect to the Cf volume concentration before the threshold. The increasing trend of EMI shielding effectiveness with respect to AC (alternating current) frequency can be attributed to enhanced conductivity at high gigahertz range. It is demonstrated that filler and frequency dependent interface effects are essential to obtain excellent electromagnetic properties of Cf/mullite composite. The present research can provide guidances for the design of ceramic-based composites applied in high-temperature EMI shielding devices. 相似文献
10.
《Intermetallics》2015
Raney-type Ni precursor alloys containing 75 at.% Al and doped with 0, 0.75, 1.5 and 3.0 at.% Ti have been produced by a gas atomization process. The resulting powders have been classified by size fraction with subsequent investigation by powder XRD, SEM and EDX analysis. The undoped powders contain, as expected, the phases Ni2Al3, NiAl3 and an Al-eutectic. The Ti-doped powders contain an additional phase with the TiAl3 DO22 crystal structure. However, quantitative analysis of the XRD results indicate a far greater fraction of the TiAl3 phase is present than could be accounted for by a simple mass balance on Ti. This appears to be a (TixNi1−x)Al3 phase in which higher cooling rates favour small x (low Ti-site occupancy by Ti atoms). SEM and EDX analysis reveal that virtually all the available Ti is contained within the TiAl3 phase, with negligible Ti dissolved in either the Ni2Al3 or NiAl3 phases. 相似文献