全文获取类型
收费全文 | 1867篇 |
免费 | 126篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 31篇 |
综合类 | 9篇 |
化学工业 | 587篇 |
金属工艺 | 28篇 |
机械仪表 | 25篇 |
建筑科学 | 134篇 |
矿业工程 | 24篇 |
能源动力 | 49篇 |
轻工业 | 159篇 |
水利工程 | 7篇 |
石油天然气 | 12篇 |
无线电 | 173篇 |
一般工业技术 | 368篇 |
冶金工业 | 118篇 |
原子能技术 | 7篇 |
自动化技术 | 275篇 |
出版年
2023年 | 14篇 |
2022年 | 19篇 |
2021年 | 51篇 |
2020年 | 45篇 |
2019年 | 44篇 |
2018年 | 32篇 |
2017年 | 38篇 |
2016年 | 73篇 |
2015年 | 73篇 |
2014年 | 100篇 |
2013年 | 108篇 |
2012年 | 89篇 |
2011年 | 106篇 |
2010年 | 68篇 |
2009年 | 101篇 |
2008年 | 81篇 |
2007年 | 79篇 |
2006年 | 72篇 |
2005年 | 74篇 |
2004年 | 50篇 |
2003年 | 54篇 |
2002年 | 40篇 |
2001年 | 25篇 |
2000年 | 26篇 |
1999年 | 32篇 |
1998年 | 41篇 |
1997年 | 28篇 |
1996年 | 25篇 |
1995年 | 28篇 |
1994年 | 29篇 |
1993年 | 28篇 |
1992年 | 31篇 |
1991年 | 24篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 20篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 19篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 17篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1974年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有2006条查询结果,搜索用时 17 毫秒
1.
Nazir Kizzie‐Hayford Doris Jaros Yvonne Schneider Harald Rohm 《International Journal of Food Science & Technology》2015,50(2):381-388
A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage. 相似文献
2.
Sakizadeh Mohamad Mohamed Mohamed M. A. Klammler Harald 《Water Resources Management》2019,33(4):1425-1437
Water Resources Management - Overexploitation of groundwater in the Malayer Plain has resulted in a continuous decline of groundwater levels over recent years with associated risks to water... 相似文献
3.
Wyatt L. Brown Douglas A. Day Harald Stark Demetrios Pagonis Jordan E. Krechmer Xiaoxi Liu Derek J. Price Erin F. Katz Peter F. DeCarlo Catherine G. Masoud Dongyu S. Wang Lea Hildebrandt Ruiz Caleb Arata David M. Lunderberg Allen H. Goldstein Delphine K. Farmer Marina E. Vance Jose L. Jimenez 《Indoor air》2021,31(1):141-155
Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations. 相似文献
4.
Hannerz Harald; Albertsen Karen; Nielsen Martin Lindhardt; Tüchsen Finn; Burr Hermann 《Canadian Metallurgical Quarterly》2004,23(3):283
This study explored whether factors related to the work environment could predict changes in body mass index (BMI) and whether the effect of psychosocial factors was dependent on baseline BMI. The sample consisted of 1,980 male employees from the Danish National Work Environment Cohort Study. Changes in BMI between 1995 and 2000 were analyzed, by multiple regression, as a function of background variables and a series of occupational variables obtained in 1995. Age, baseline BMI, job insecurity, and psychological demands predicted changes in BMI. Job insecurity and high or low psychological demands increased the likelihood of weight gain among obese employees, whereas they increased the likelihood of weight loss among employees with a low BMI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
This paper presents a half-rate clock and data recovery circuit (CDR)that combines the fast acquisition of a phase selection (PS) delay-locked loop (DLL) with the low jitter of a phase-locked loop (PLL). The PLL acquisition time improves considerably with use of a phase frequency magnitude detector(PFMD) that feeds back an estimate of the magnitude of the frequency difference in addition to the sign. Measurements in 0.5/spl mu/m CMOS technology show operation up to 700 Mb/s, a 7% acquisition range, an initial acquisition time of 8 bit times with jitter of 30% bit time, and jitter of 16 ps after the PLL acquires lock. With a phase frequency detector (PFD), the PLL locks in about 700 ns from an initial frequency difference of 7%. Measurements using a PFMD show the 700 ns PLL acquisition time is reduced on average by about a factor of 5 to 140 ns from an initial 7% frequency difference. The power dissipation is 300mW. 相似文献
6.
7.
Methodological issues in geropsychological assessment research are discussed and exemplified with recent investigations. Increased use of short-term longitudinal designs, more diverse and representative sampling, and routine inclusion of measures of health are among the recommendations made for future studies. Caution is urged in the application of new tests or screening batteries until sufficient independent validation studies are completed. Research contrasting neuropsychological performance of older persons from different racial and ethnic groups is briefly reviewed, and applications of geropsychological assessment to practical arenas such as competency determination are critiqued. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
An inulin syrup made from Jerusalem artichoke tubers, either in its commercial form or after ultrafiltration, was freeze-dried and used as a prebiotic ingredient in the small-scale manufacture of wafer crackers. The flours used for the preparation of wafer batters were from wheat, rye or spelt wheat, or 1:1 combinations of wheat flour and rye flour or wheat flour and spelt wheat flour. Batter viscosity was strongly influenced by the selection of the flour type, but remained within technologically acceptable limits. The ultrafiltration of the inulin syrup, using a 1 kDa membrane, resulted in a significant reduction of the content of free sugars and minerals which, in turn, had a significant impact on the CIE-Lab color values of the wafer crackers. Using spelt wheat flour instead of wheat flour significantly increased wafer cracker firmness measured by penetration, as did the incorporation of ultrafiltered freeze-dried instead of native freeze-dried Jerusalem artichoke syrup. Sensory analysis revealed a significant influence of product formulation on appearance, flavor and texture of the wafer crackers. It can be concluded from quality scores, which were calculated by using weighting factors assigned to the sensory attributes, that wheat flour may be partially replaced by rye flour or spelt wheat flour without negatively affecting the sensory properties of the wafer crackers. 相似文献
9.
Ohne Zusammenfassung 相似文献
10.