全文获取类型
收费全文 | 555篇 |
免费 | 52篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 3篇 |
综合类 | 3篇 |
化学工业 | 164篇 |
金属工艺 | 10篇 |
机械仪表 | 17篇 |
建筑科学 | 16篇 |
矿业工程 | 2篇 |
能源动力 | 26篇 |
轻工业 | 102篇 |
水利工程 | 12篇 |
石油天然气 | 21篇 |
无线电 | 46篇 |
一般工业技术 | 91篇 |
冶金工业 | 31篇 |
原子能技术 | 3篇 |
自动化技术 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 25篇 |
2021年 | 48篇 |
2020年 | 27篇 |
2019年 | 30篇 |
2018年 | 36篇 |
2017年 | 37篇 |
2016年 | 32篇 |
2015年 | 24篇 |
2014年 | 35篇 |
2013年 | 49篇 |
2012年 | 35篇 |
2011年 | 51篇 |
2010年 | 37篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有612条查询结果,搜索用时 0 毫秒
111.
112.
113.
Marticorena RM Hunter J Macleod S Petershofer E Kashani M DE LA Cruz J Cook R Dacoiris N McFarlane PA Goldstein MB Donnelly SM 《Hemodialysis international. International Symposium on Home Hemodialysis》2011,15(2):243-249
Buttonhole cannulation is a method of cannulation of native arteriovenous fistulae traditionally practiced by self‐cannulators. At St Michael's Hospital, this method has been modified to allow its use in problematic fistulae by multiple cannulators. In a busy dialysis unit, the need for a few specific cannulators to establish the tunnel tracks in combination with the variable dialysis schedules creates logistical challenges. A new method of creating tunnel tracks with the use of the BioHole? device was evaluated. Buttonhole tracks were created in 12 patients using a peg of polycarbonated material with a holder (BioHole? kit). The peg was inserted into the path left by the hemodialysis sharp needle following the index cannulation. Four of the 12 patients had an alternate access. Buttonhole tracks were successfully created in all the patients, albeit in 2 patients, the initial attempt to establish buttonhole tracks was aborted due to complications and the procedure was rescheduled. Compared with the modified buttonhole technique, pain on cannulation following track creation was significantly less in the BioHole? group (P<0.001). Ease of cannulation was significantly improved in the BioHole? group (P<0.05) when compared with that in thrice‐weekly patients using the modified buttonhole technique. Hemostasis postdialysis did not differ between the study groups. The use of the BioHole? device is effective in the creation of tunnel tracks for buttonhole cannulation, is associated with less pain, and simplifies the logistics of arranging patient and nurses' schedules. 相似文献
114.
N. Fatourehchi M. Sohrabi S. J. Royaee S. M. Mirarefin 《Petroleum Science and Technology》2013,31(15):1578-1589
Abstract Light olefins are basic raw materials for petrochemical industries and the global demand for the latter is growing. The authors investigated the conversion of methanol to light olefins in presence of acidic SAPO-34 molecular sieve as the reaction catalyst. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The molecular sieve was then changed into protonated form by ion exchange process with ammonium chloride at 80°C. A kinetic study was carried out within the temperature range of 375–425°C and 4 bar pressure using a differential fixed bed reactor. An appropriate kinetic model was presented and the kinetic parameters were evaluated as functions of temperature. In addition, the formation of light olefins was implemented in a fluidized bed reactor under a wide range of operating conditions. The experimental results were correlated with those predicted from a hydrodynamic model. Taguchi's experimental design method was applied to determine the optimum operating parameters of this process conducted in the fluidized bed reactor. The optimized parameters were the following: temperature = 425°C; ratio of inlet gas velocity to minimum fluidizing velocity (U0/Umf) = 7; catalyst mean particle size = 240 μm. 相似文献
115.
In the present study, a number of phosphorus modified HZSM-5(Si/Al = 250) zeolite as MTO catalyst were prepared and characterized by various methods. A kinetic model for MTO process over PZSM-5 catalyst was developed based on data obtained from a differential fixed bed reactor within the temperature range of 360–425°C and 1 bar pressure applying the Langmuir-Hinshelwood formulation. The kinetic parameters were evaluated from the experimental data using genetic algorithm. It was found that the predicted data from the model were well correlated with the experimental results, indicating that ethylene and propylene are primary olefins. 相似文献
116.
117.
King Daniel W.; King Lynda A.; Erickson Darin J.; Huang Mina T.; Sharkansky Erica J.; Wolfe Jessica 《Canadian Metallurgical Quarterly》2000,109(4):624
There has been recent concern about the degree to which posttraumatic stress disorder (PTSD) symptomatology influences reports of prior exposure to highly stressful life events. In this longitudinal study of 2,942 male and female Gulf War veterans, the authors documented change in stressor reporting across 2 occasions and the association between change and PTSD symptom severity. A regression-based cross-lagged analysis was used to examine the relationship between PTSD symptom severity and later reported stressor exposure. Shifts in reporting over time were modestly associated with PTSD symptom severity. The cross-lagged analysis revealed a marginal association between Time 1 PTSD symptom severity and Time 2 reported stressor exposure for men and suggested that later reports of stressor exposure are primarily accounted for by earlier reports and less so by earlier PTSD symptomatology. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
118.
Ayako Nakano Mina Ushiyama Yoshiharu Iwabuchi Susumi Hatakeyama 《Advanced Synthesis \u0026amp; Catalysis》2005,347(14):1790-1796
Compound 20 , a pseudoenantiomer of β‐isocupreidine (β‐ICD), was synthesized from quinine employing a Barton reaction of nitrosyl ester 13 and acid‐catalyzed cyclization of carbinol 18 as key steps. The Baylis–Hillman reaction of benzaldehyde, p‐nitrobenzaldehyde, and hydrocinnamaldehyde with 1,1,1,3,3,3‐hexafluoroisopropyl acrylate (HFIPA) using 20 as a chiral amine catalyst was found to give the corresponding S‐enriched adducts in high optical purity (>91% ee) in contrast to the β‐ICD‐catalyzed reaction which affords R‐enriched adducts. This result suggests that compound 20 can serve as an enantiocomplementary catalyst of β‐ICD in the asymmetric Baylis–Hillman reaction of aldehydes with HFIPA. 相似文献
119.
Haddaji Younesse Hamdane Hasna Majdoubi Hicham Mansouri Said Allaoui Driss El bouchti Mehdi Tamraoui Youssef Manoun Bouchaib Oumam Mina Hannache Hassan 《SILICON》2021,13(7):2389-2400
Silicon - Geopolymers produced with metakaolin (MK) and thermally untreated phosphate sludge (PS) are beneficial and environmentally advantageous materials, but their fragility limits its... 相似文献
120.
Nam-In Kim Miad Yarali Mina Moradnia Muhammad Aqib Che-Hao Liao Feras AlQatari Mingtao Nong Xiaohang Li Jae-Hyun Ryou 《Advanced functional materials》2023,33(10):2212538
Extreme environments are often faced in energy, transportation, aerospace, and defense applications and pose a technical challenge in sensing. Piezoelectric sensor based on single-crystalline AlN transducers is developed to address this challenge. The pressure sensor shows high sensitivities of 0.4–0.5 mV per psi up to 900 °C and output voltages from 73.3 to 143.2 mV for input gas pressure range of 50 to 200 psi at 800 °C. The sensitivity and output voltage also exhibit the dependence on temperature due to two origins. A decrease in elastic modulus (Young's modulus) of the diaphragm slightly enhances the sensitivity and the generation of free carriers degrades the voltage output beyond 800 °C, which also matches with theoretical estimation. The performance characteristics of the sensor are also compared with polycrystalline AlN and single-crystalline GaN thin films to investigate the importance of single crystallinity on the piezoelectric effect and bandgap energy-related free carrier generation in piezoelectric devices for high-temperature operation. The operation of the sensor at 900 °C is amongst the highest for pressure sensors and the inherent properties of AlN including chemical and thermal stability and radiation resistance indicate this approach offers a new solution for sensing in extreme environments. 相似文献