全文获取类型
收费全文 | 1853篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 220篇 |
金属工艺 | 23篇 |
机械仪表 | 24篇 |
建筑科学 | 139篇 |
矿业工程 | 2篇 |
能源动力 | 32篇 |
轻工业 | 284篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
无线电 | 185篇 |
一般工业技术 | 264篇 |
冶金工业 | 501篇 |
原子能技术 | 16篇 |
自动化技术 | 148篇 |
出版年
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 26篇 |
2018年 | 33篇 |
2017年 | 28篇 |
2016年 | 21篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 61篇 |
2012年 | 57篇 |
2011年 | 87篇 |
2010年 | 55篇 |
2009年 | 60篇 |
2008年 | 68篇 |
2007年 | 63篇 |
2006年 | 47篇 |
2005年 | 58篇 |
2004年 | 58篇 |
2003年 | 42篇 |
2002年 | 40篇 |
2001年 | 45篇 |
2000年 | 25篇 |
1999年 | 48篇 |
1998年 | 133篇 |
1997年 | 94篇 |
1996年 | 52篇 |
1995年 | 51篇 |
1994年 | 35篇 |
1993年 | 42篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 23篇 |
1987年 | 27篇 |
1986年 | 25篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 17篇 |
1980年 | 19篇 |
1979年 | 15篇 |
1978年 | 19篇 |
1977年 | 15篇 |
1976年 | 31篇 |
1973年 | 11篇 |
1972年 | 10篇 |
1971年 | 13篇 |
排序方式: 共有1877条查询结果,搜索用时 15 毫秒
1.
2.
3.
Irine Banu Lucy 《Journal of Materials Science》2007,42(14):5875-5879
Capacitance and dielectric loss measurements were carried out using an Al/Cu–GeO2/Al sandwich structure for 0 to 10 vol% Cu films, 120–400 nm thick, deposited at 0.4–1.5 nm/s in the frequency and temperature
range 1–106 Hz and 90–573 K, respectively. The variation of capacitance and dielectric loss with frequency and temperature follows the
Goswami and Goswami model. Capacitance decreases slowly with increasing thickness and also varies with the change in deposition
rate of the cermet film. 相似文献
4.
Butler Emily A.; Egloff Boris; Wlhelm Frank H.; Smith Nancy C.; Erickson Elizabeth A.; Gross James J. 《Canadian Metallurgical Quarterly》2003,3(1):48
At times, people keep their emotions from showing during social interactions. The authors' analysis suggests that such expressive suppression should disrupt communication and increase stress levels. To test this hypothesis, the authors conducted 2 studies in which unacquainted pairs of women discussed an upsetting topic. In Study 1, one member of each pair was randomly assigned to (a) suppress her emotional behavior, (b) respond naturally, or (c) cognitively reappraise in a way that reduced emotional responding. Suppression alone disrupted communication and magnified blood pressure responses in the suppressors' partners. In Study 2, suppression had a negative impact on the regulators' emotional experience and increased blood pressure in both regulators and their partners. Suppression also reduced rapport and inhibited relationship formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Almond preferences were produced by giving rats a mixture of almond and sucrose (Experiments 1-4) or saccharin (Experiment 4). A subsequent extinction procedure consisted of either repeated 2-bottle almond versus water tests (Experiment 1) or repeated exposure to almond alone (Experiments 2-4). The main independent variable was whether access to food following a session was given immediately, 30 min later, or 120 min later. No effect of extinction was found in any experiment. An important finding was that varying the delay until food access had no detectable effect. It was concluded that inadvertent flavor-food associations do not maintain preference for the flavor under extinction conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
8.
Aqueous extracts of the coralline red algaeBossiella orbigniana have been shown to catalyze the enzymatic oxidation of arachidonic acid to a previously unreported ω6 eicosapentaenoic acid
product. This unique fatty acid contains a conjugated tetraene with absorption maxima at 293, 306, and 321 nm, and was identified
by spectral methods as 5(Z),8(Z),10(E),12(E),14(Z)-eicosapentaenoic acid. The compound was given the trivial name bosseopentaenoic
acid. Under experimental conditions, production of bosseopentaenoic acid was linear up to 2 hr and dioxygen was consumed.
Bosseopentaenoic acid, along with several other conjugated tetraenes, was also present in the algae endogenously as revealed
by a comparison of the ultraviolet (UV) spectra and the high-performance liquid chromatographic (HPLC) pattern of the purified
product and the organic extract ofBossiella. 相似文献
9.
ABSTRACT: The effect of post-cooking holding-time on sensory assessment of low (89 g/kg) and high (218 g/kg) fat beefburgers was assessed. Burgers were served to panelists approximately 3 or 18 min after cooking. Fat content influenced fattiness, moistness/juiciness and overall appearance (P < 0.05), overall acceptability and overall texture (P< 0.01) and tenderness and crumbliness (p<0.001). Burgers with the higher fat content had higher scores. Holding-time influenced sensory overall appearance only with lower scores at extended holding times (P < 0.01). Treatment differences were small, mostly less than one sensory scale unit. Higher lightness and yellowness values were found for burgers with higher fat contents. 相似文献
10.
Neal E. Craft Katherine S. Epler Therese A. Butler Willie E. May Regina G. Ziegler 《Journal of research of the National Institute of Standards and Technology》1993,98(3):355-359
Aliquots of serum collected in a large case-control study of cervical cancer were stored at −70°C for up to 4 years during implementation of the study. When 500 μL serum aliquots were thawed in preparation for carotenoid and vitamin A assays, volumes were noticeably variable and fell below 500 μL in the majority of the samples. We were concerned about evaporation/sublimation during storage of the samples because loss of water would concentrate the analytes of interest. We evaluated the use of density and sodium ion concentration measurements to confirm its occurrence. We found that serum density was an unreliable indicator of extent of volume loss since the anticipated increases in density due to evaporation were of the same magnitude as inter-individual variation in serum density. In contrast, Na+ concentration is tightly regulated and would rise if water had been lost from the samples. In a representative sample of serum aliquots from the case-control study, 24 of 25 vials contained less than 500 μL of serum. The mean sodium ion concentration (138.1 ± 3.6 mmol/L) was within the normal range for human serum of 136–145 mmol/L, and no correlation was observed between serum volume and Na+ concentration. These results strongly suggest that the observed low volumes were not due to evaporative losses. Instead, the variably low volumes of serum aliquots were probably due to pipetting errors in the initial aliquotting resulting from the use of air-displacement pipettes. 相似文献