全文获取类型
收费全文 | 167篇 |
免费 | 17篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 61篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 4篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 5篇 |
石油天然气 | 2篇 |
无线电 | 12篇 |
一般工业技术 | 24篇 |
冶金工业 | 31篇 |
原子能技术 | 4篇 |
自动化技术 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 12篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 4篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有184条查询结果,搜索用时 46 毫秒
31.
The effects of Rivastigmine, a novel centrally-acting anticholinesterase agent, were evaluated on cerebral edema, neurological and motor deficits, and impairment of spatial memory induced in mice by closed-head injury (CHI). Severe injury was induced in the left hemisphere of mice under ether anesthesia. Rivastigmine (1 or 2 mg/kg) or saline (10 ml/kg) was injected SC 5 min later. Rivastigmine (2 mg/kg) reduced cerebral edema by at least 50% (p < 0.01), 24 h after CHI and accelerated the recovery of motor function 7 and 14 days after CHI. Control mice (n = 24), previously trained to find the goal platform in a Morris water maze failed to recall or relearn its position for at least 11 days post-injury. Those given a single injection of Rivastigmine (2 mg/kg) regained their pre-test latencies by the third day after CHI. The neuroprotective effects of Rivastigmine on brain edema, neurological and motor function, and performance in the Morris water maze were completely antagonized by simultaneous SC injection of either scopolamine (0.5 mg/kg) or mecamylamine (2.5 mg/kg). The antagonists alone had no significant effect on any of these parameters. These data show that the reduction by Rivastigmine of the immediate and long-term sequelae of brain injury are mediated by increased cholinergic activity at both muscarinic and nicotinic receptors. 相似文献
32.
The operations of Nissen, Hill, and Belsey are adequate in controlling esophaegeal reflux in the majority of patients. In a small percentage however, objective and subjective evidence of esophagitis persists in spite of repeated operations to restore lower esophageal sphincter competency. These failures are then usually treated by operative procedures of great magnitude involving organ interposition. Repeated antireflux operations directed to the gastroesophageal area may in some instances result in impairment of blood supply with an increased risk of both esophageal and gastric fistulae. In the past many observers have felt that reflux esophagitis resulted solely from the effects of acid-pepsin secretions bathing the distal esophagus. Recently experimental and clinical data have indicated the importance of duodenal contents in the etiology and perpetuation of reflux esophagitis. During a recent two year period, 6 patients with persistent reflux esophagitis uncontrolled by repeated antireflux procedures have been seen on our service. These 6 patients, underwent 12 unsuccessful antireflux operations elsewhere. Three of the 6 patients had also been subjected to vagotomy-antrectomy for a coexisting duodenal ulcer. A marked lowering of gastric acidity took place but esophageal reflux and esophagitis persisted. These three patients were treated on our service by takedown of the Billroth I anastomosis, closure of the duodenal stump and diversion of the duodenal contents into a Roux-en-Y limb. Three other patients who had undergone unsuccessful antireflux procedures alone were subjected to antral resection, Roux-en-Y diversion and transthoracid vagotomy. This simplified appraoch to the treatment of persistent esophageal reflux uncontrolled by repeated antireflux procedures has given satisfactory results. The operation should be considered when technical considerations preclude further surgical attempts to perform another effective antireflux operation. Total duodenal diversion should, however, not be considered as the primary operation for the patient suffering from reflux esophagitis. However, in circumstances discussed above this direct approach appears preferable to major resectional procedures. 相似文献
33.
Defocused speckle correlation is introduced as a tool for measuring the response in metal sheets during percussion laser drilling. For this procedure the fourth-harmonic Nd:YAG wavelength (266 nm) was used in pulsed mode. The method provides a cost-efficient and robust alternative to speckle interferometry for the study of the small deformations that appear during laser processing. The accuracy was shown to be of the order of a few tens of microradians for the tilt component that is measured, which translates to a few nanometers in deflection when the component is spatially integrated. In the measurements, deflections in the form of craters as large as 50 nm were detected on the back sides of silver and copper sheets. The diameters of the craters were 300 microm in the silver and 150 microm in the copper sheet; the output diameter of the hole was -5 microm. 相似文献
34.
Ilaria Patruno Dr. Dawn Thompson Dr. Sergio Dall'Angelo Prof. Albert D. Windhorst Dr. Danielle J. Vugts Dr. Alex J. Poot Dr. Nimesh Mody Prof. Matteo Zanda 《ChemMedChem》2020,15(16):1579-1590
Fenretinide (4-HPR) is a synthetic derivative of all-trans-retinoic acid (ATRA) characterised by improved therapeutic properties and toxicological profile relative to ATRA. 4-HPR has been mostly investigated as an anti-cancer agent, but recent studies showed its promising therapeutic potential for preventing metabolic syndrome. Several biological targets are involved in 4-HPR's activity, leading to the potential use of this molecule for treating different pathologies. However, although 4-HPR displays quite well-understood multitarget promiscuity with regards to pharmacology, interpreting its precise physiological role remains challenging. In addition, despite promising results in vitro, the clinical efficacy of 4-HPR as a chemotherapeutic agent has not been satisfactory so far. Herein, we describe the preparation of a library of 4-HPR analogues, followed by the biological evaluation of their anti-cancer and anti-obesity/diabetic properties. The click-type analogue 3 b showed good capacity to reduce the amount of lipid accumulation in 3T3-L1 adipocytes during differentiation. Furthermore, it showed an IC50 of 0.53±0.8 μM in cell viability tests on breast cancer cell line MCF-7, together with a good selectivity (SI=121) over noncancerous HEK293 cells. Thus, 3 b was selected as a potential PET tracer to study retinoids in vivo, and the radiosynthesis of [18F] 3b was successfully developed. Unfortunately, the stability of [18F] 3b turned out to be insufficient to pursue imaging studies. 相似文献
35.
Attila Varga Istvan Keppler Laszlo Fenyvesi 《Journal of Mechanical Science and Technology》2020,34(6):2327-2332
Our goal is the determination of the material flow processes around the mixing screws and introducing a new mixing index which can characterize the perform 相似文献
36.
Characterization of electronic displays using CMOS single‐photon avalanche diode image sensors
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hanning Mai Istvan Gyongy Neale A.W. Dutton Robert K. Henderson Ian Underwood 《Journal of the Society for Information Display》2018,26(4):255-261
Advanced complementary metal‐oxide semiconductor‐compatible single‐photon avalanche diode array technology is progressing rapidly and is being deployed in a wide range of applications. We report for the first time the use of a complementary metal‐oxide semiconductor‐compatible single‐photon avalanche diode array to perform detailed optical measurements on pixels of an organic light‐emitting diode microdisplay at very high sampling rate, very low light level, and over a very wide dynamic range of luminance. This offers a clear demonstration of the huge potential of this single‐photon avalanche diode technology to reveal hitherto obscure details of the optical characteristics of individual and groups of organic light‐emitting diode pixels. 相似文献
37.
The activity and selectivity in the catalytic reduction of NO by a mixture of CO and H2 of three PdO-MoO3/-Al2O3 catalysts are compared in the presence of varying amounts of oxygen at reaction temperatures from 100 to 550°C. The catalysts were prepared by different methods and contain about 2% Mo and 2% Pd. Results are compared with those for PdO/-Al2O3, PdO-MoO3/-Al2O3 containing 2% Pd and 20% Mo, and a commercial Pt-Rh catalyst. The PdO-MoO3/-Al2O3 catalysts are more active for the selective reduction of NO to N2 and N2O than PdO/-Al2O3 under slightly oxidizing conditions at temperatures from 300 to 550°C. At these reaction conditions, the fresh PdO-MoO3/-Al2O3 catalysts are comparable with a commercial Pt-Rh catalyst. The improved activity of PdO-MoO3/-Al2O3 relative to PdO/-Al2O3 is believed to be due to the interaction between Pd and Mo. The effect of O2 on the activity and selectivity of these catalysts is different in the reduction of NO by H2, by CO, and by a mixture of H2 and CO. The results using the mixture of reductants cannot be inferred from the results with the single reductants. 相似文献
38.
Synthesis,Characterization and Immunological Evaluation of Self‐Adjuvanting Group A Streptococcal Vaccine Candidates Bearing Various Lipidic Adjuvanting Moieties
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Vincent Fagan Dr. Waleed M. Hussein Mei Su Ashwini K. Giddam Dr. Michael R. Batzloff Prof. Michael F. Good Prof. Istvan Toth Dr. Pavla Simerska 《Chembiochem : a European journal of chemical biology》2017,18(6):545-553
Four group A streptococcal glycolipopeptide vaccine candidates with different lipidic adjuvanting moieties were prepared and characterized. The immunogenicity of the compounds was evaluated by macrophage and dendritic cell uptake studies and by in vivo quantification of systemic IgG antibody by ELISA. Three of the candidates showed significant induction of the IgG response. 相似文献
39.
The reaction of (NO + C3H8 + O2) can result in selective formation of NO2 over H-ZSM5, Cu,H-ZSM5, Ag,H-ZSM5, and Li,H-ZSM5 catalysts when the concentrations of NO and O2 are 0.1 and 9%, SV > 60,000 h−1 (typical for automotive exhausts), and C3H8/NO > 1. Despite stoichiometric excess of reductant hydrocarbon below this limit, the in situ formed NO2 does not react with C3H8, thus conversion of NO to N2 is negligible. NO can be reduced by C3H8 selectively to N2 only when C3H8/NO ≧ 1. Contrary to many suggestions the reaction temperature, concentration of oxygen, space velocity, and type of exchange
ions have minor influence on the selectivity for N2. These parameters affect the rates of reactions (NO + 2), (C3H8 + NOx) and (C3H8 + O2), therefore they also affect the production of N2 in the HC-SCR process, but only when the ratio of C3H8/NO permits. The metal-exchanged zeolites were prepared in situ by solid-state ion exchange from H-ZSM5. Despite the low degree
of copper exchange (63%), Cu,H-ZSM5 produces substantially more N2 than H-ZSM5, Ag,H-ZSM5, or Li,H-ZSM5. However, the selectivity for N2 is lowest over Cu,H-ZSM5, which also produces considerable NO2 in the reaction of (NO + C3H8 + O2) even at C3H8/NO ≧ 1. Contrary to prior findings, the catalytic activity of Cu,H-ZSM5 for the oxidation of NO by O2 to NO2 in absence of hydrocarbon was comparable to that of H-ZSM5 at high space velocities (2.3 l g−1 min−1). By replacing 30 and 40% of the protons of H-ZSM5 by Ag+ and Li+ ions in Ag,H-ZSM5 and Li,H-ZSM5, respectively, the catalytic activity for this reaction becomes negligible at temperatures
≧100°C. Some mechanistic consequences of these experimental observations are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
40.
A TinyOS-enabled MICA2-based wireless neural interface 总被引:2,自引:0,他引:2
Farshchi S Nuyujukian PH Pesterev A Mody I Judy JW 《IEEE transactions on bio-medical engineering》2006,53(7):1416-1424
Existing approaches used to develop compact low-power multichannel wireless neural recording systems range from creating custom-integrated circuits to assembling commercial-off-the-shelf (COTS) PC-based components. Custom-integrated-circuit designs yield extremely compact and low-power devices at the expense of high development and upgrade costs and turn-around times, while assembling COTS-PC-technology yields high performance at the expense of large system size and increased power consumption. To achieve a balance between implementing an ultra-compact custom-fabricated neural transceiver and assembling COTS-PC-technology, an overlay of a neural interface upon the TinyOS-based MICA2 platform is described. The system amplifies, digitally encodes, and transmits neural signals real-time at a rate of 9.6 kbps, while consuming less than 66 mW of power. The neural signals are received and forwarded to a client PC over a serial connection. This data rate can be divided for recording on up to 6 channels, with a resolution of 8 bits/sample. This work demonstrates the strengths and limitations of the TinyOS-based sensor technology as a foundation for chronic remote biological monitoring applications and, thus, provides an opportunity to create a system that can leverage from the frequent networking and communications advancements being made by the global TinyOS-development community. 相似文献