全文获取类型
收费全文 | 27283篇 |
免费 | 2091篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 165篇 |
综合类 | 10篇 |
化学工业 | 5941篇 |
金属工艺 | 445篇 |
机械仪表 | 573篇 |
建筑科学 | 836篇 |
矿业工程 | 52篇 |
能源动力 | 631篇 |
轻工业 | 5663篇 |
水利工程 | 309篇 |
石油天然气 | 129篇 |
武器工业 | 1篇 |
无线电 | 1090篇 |
一般工业技术 | 4426篇 |
冶金工业 | 5383篇 |
原子能技术 | 84篇 |
自动化技术 | 3659篇 |
出版年
2024年 | 53篇 |
2023年 | 276篇 |
2022年 | 287篇 |
2021年 | 765篇 |
2020年 | 685篇 |
2019年 | 711篇 |
2018年 | 1235篇 |
2017年 | 1207篇 |
2016年 | 1264篇 |
2015年 | 976篇 |
2014年 | 1147篇 |
2013年 | 2331篇 |
2012年 | 1822篇 |
2011年 | 1650篇 |
2010年 | 1324篇 |
2009年 | 1190篇 |
2008年 | 1204篇 |
2007年 | 1101篇 |
2006年 | 728篇 |
2005年 | 611篇 |
2004年 | 574篇 |
2003年 | 545篇 |
2002年 | 474篇 |
2001年 | 361篇 |
2000年 | 295篇 |
1999年 | 332篇 |
1998年 | 1910篇 |
1997年 | 1203篇 |
1996年 | 745篇 |
1995年 | 397篇 |
1994年 | 307篇 |
1993年 | 323篇 |
1992年 | 91篇 |
1991年 | 75篇 |
1990年 | 63篇 |
1989年 | 58篇 |
1988年 | 87篇 |
1987年 | 75篇 |
1986年 | 62篇 |
1985年 | 71篇 |
1984年 | 61篇 |
1983年 | 34篇 |
1982年 | 37篇 |
1981年 | 60篇 |
1980年 | 59篇 |
1978年 | 30篇 |
1977年 | 104篇 |
1976年 | 207篇 |
1975年 | 33篇 |
1973年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Vicente M. Gómez-López María I. Gil Ana Allende Jeroen Blancke Lien Schouteten María V. Selma 《Food and Bioprocess Technology》2014,7(12):3390-3397
The fresh-cut industry must treat process water to guarantee its microbial quality before reuse or recirculation back into the processing line. In the present study, the suitability of high-power ultrasound (HPU) for disinfecting and recycling process water was evaluated. An ultrasonic horn (20 kHz) was used to inactivate Escherichia coli O157:H7 inoculated in five types of process water which showed different physical and chemical characteristics. Differences in the inactivation level of E. coli O157:H7 at different HPU densities (0.14, 0.28, 0.56, and 1.12 kW/L) with controlled (20–25 °C) and uncontrolled (15–72 °C, 3.6 °C/min) temperature increase were studied. Results showed that the higher the power density and temperature, the higher the efficiency, reaching up to 6 log reductions of E. coli O157:H7. Alkalinity (between 0 and 253 mg HCO3 ?/L) and organic matter concentration (between 9 and 3,525 mg O2/L) in water did not reduce ultrasonic efficacy against E. coli O157:H7. Agglomerates >90 μm, which represented 34 % of those present in the process water, were reduced to only 11 % by HPU. Results indicate that HPU can be successfully applied to treat process water of the fresh produce industry because the antimicrobial efficacy was not affected by the continuous variation of the process water quality. HPU can be a suitable technology for the fresh produce industry to be able to reduce consumption of water and decrease wastewater and the generation of disinfection by-products. 相似文献
992.
Alírio Soares Boaventura Nuno Borges Carvalho 《International Journal of Wireless Information Networks》2013,20(1):67-73
This paper presents a low-power wakeup radio (WUR) for application in indoor location systems. The presented radio has a better performance than the state-of-the-art radios, since it has low-power consumption, only 10 μW and it is perfectly integrated into a wireless sensor network based on ZigBee, which is used for location purposes. This performance was achieved due to an optimised radio frequency design of the WUR, which was embedded with a low-cost/low-power processor, and due to an enhanced control algorithm. Moreover, a software defined radio approach has been used to implement the WUR protocol. The WUR was designed and integrated in an existing WSN-based indoor location system which was originally based on a periodic sleep-wake up duty-cycled protocol. In the WUR protocol the location sensor is kept in deep sleep mode until it receives an external wake-up order. According to estimates, with this scheme, the battery lifetime can be increased from 200 days (using conventional duty-cycle protocol) up to almost 8000 days (sensor waken-up few times per day). 相似文献
993.
Belén A. Acevedo María G. Chaves María V. Avanza Eduardo S. Dellacassa 《International Journal of Food Science & Technology》2014,49(2):423-428
The use of freeze‐drying for concentrating lime Rangpur juice was investigated. This procedure allowed obtaining concentrated Rangpur lime juices between 23 and 51.3 °Brix, without affecting their organoleptic and nutritional characteristics. The efficiency of the procedure was inversely related to the film thickness of the matrix to be lyophilised. The sublimation speed per unit area diminished with the reduction in the residual moisture content of the juice. The mathematical model that fitted to the concentration procedure allowed to predict the time required for concentrating Rangpur lime by freeze‐drying starting from samples of different thickness. When compared with other citric juices evaluated, the Rangpur lime juice was the most suitable for freeze‐drying concentration. The results could be used to devise optimal industrial freeze‐drying cycles for processing Rangpur lime juices at different concentrations. 相似文献
994.
995.
Ana Belén Bautista-Ortín Rim Ben Abdallah Liliana del Rocío Castro-López María Dolores Jiménez-Martínez Encarna Gómez-Plaza 《International journal of molecular sciences》2016,17(1)
The transference and reactivity of proanthocyanidins is an important issue that affects the technological processing of some fruits, such as grapes and apples. These processes are affected by proanthocyanidins bound to cell wall polysaccharides, which are present in high concentrations during the processing of the fruits. Therefore, the effective extraction of proanthocyanidins from fruits to their juices or derived products will depend on the ability to manage these associations, and, in this respect, enzymes that degrade these polysaccharides could play an important role. The main objective of this work was to test the role of pure hydrolytic enzymes (polygalacturonase and cellulose) and a commercial enzyme containing these two activities on the extent of proanthocyanidin-cell wall interactions. The results showed that the modification promoted by enzymes reduced the amount of proanthocyanidins adsorbed to cell walls since they contributed to the degradation and release of the cell wall polysaccharides, which diffused into the model solution. Some of these released polysaccharides also presented some reactivity towards the proanthocyanidins present in a model solution. 相似文献
996.
Biosynthesis and purification of histidine‐tagged human soluble catechol‐O‐methyltransferase
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
997.
Ana Laura CIMADOR Emeli Luciana GALANTE Lucila Ibel MUÑOZ Patricia Silvia ROMANO Antonella Denisse LOSINNO María Cristina VANRELL 《Biocell》2019,43(1):13-20
Trypanosoma rangeli and T. cruzi are both parasitic unicellular species that infect humans. Unlike T. cruzi,
the causative agent of Chagas disease, T. rangeli is an infective and non-pathogenic parasite for humans, but pathogenic
for vectors from the Rhodnius genus. Because both species can coexist in different hosts and overlap their infective
cycles but very little is known about the infection of T. rangeli in mammalian cells, we decided to characterize both the
development of this parasite in cell culture and the effect of therapeutic agents with potential trypanocidal action on
it. We found that T. rangeli exhibits a cycle of infection in Vero cells similar to that for T. cruzi and that the repurposed
drug, 17-AAG, and the natural extract Artemisia sp. essential oil produce a toxic effect on epimastigotes showing
a trypanocidal action from the fifth day of culture. Both treatments also affected the infection of trypomastigotes
and reduced the capacity of replication of amastigotes of T. rangeli. Since T. cruzi / T. rangeli coinfection cases have
been reported, the finding of drugs with potential activity against both species could be significant in the future.
Furthermore, studies of susceptibility of both species to drugs could also help to know the different mechanisms of
pathogenicity in humans displayed by T. cruzi that are absent in T. rangeli 相似文献
998.
Igor A. Magno Fabrício A. Souza Marlo O. Costa Jacson M. Nascimento Adrina P. Silva Thiago S. Costa 《Materials Science & Technology》2019,35(7):791-806
Horizontal directional solidification and precipitation hardening experiments were performed with the Al5.5Si3Cu alloy. Solidification thermal and microstructural parameters such as growth and cooling rates (VL and TR, respectively) and the secondary dendrite arm spacing (λ2) were determined experimentally. As-solidified samples were selected and submitted to the T6-heat treatment (T6-HT). The T6-HT was carried out considering two solution times: 8 and 5?h at 490?±?2°C, followed by quenching in warm water (60?±?2°C), aging for 5?h at 155?±?2°C and air-cooling. Higher HV values were observed for the solution time of 5 h. As highlights of this work, the influence of the processing parameters (VL, TR and λ2) on the distribution, morphology and size of the eutectic Si particles has been investigated. 相似文献
999.
1000.