全文获取类型
收费全文 | 1455篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 65篇 |
金属工艺 | 5篇 |
机械仪表 | 12篇 |
建筑科学 | 35篇 |
矿业工程 | 6篇 |
能源动力 | 18篇 |
轻工业 | 32篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 35篇 |
一般工业技术 | 64篇 |
冶金工业 | 1144篇 |
原子能技术 | 6篇 |
自动化技术 | 39篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 6篇 |
2013年 | 31篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 35篇 |
1998年 | 330篇 |
1997年 | 198篇 |
1996年 | 137篇 |
1995年 | 65篇 |
1994年 | 75篇 |
1993年 | 67篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 21篇 |
1988年 | 17篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 40篇 |
1976年 | 81篇 |
1974年 | 2篇 |
1960年 | 2篇 |
1957年 | 2篇 |
1920年 | 2篇 |
排序方式: 共有1470条查询结果,搜索用时 15 毫秒
11.
Numerical simulation of solvent and water assisted electrical heating of oil sands including aquathermolysis and thermal cracking reactions 下载免费PDF全文
Hassan Hassanzadeh Moosa Rabiei Faradonbeh Thomas Harding 《American Institute of Chemical Engineers》2017,63(9):4243-4258
Simulations of bitumen recovery using solvent‐ and water‐assisted electrical heating of oil sands are presented to evaluate the process and to study gas generation. Aquathermolysis and thermal cracking and dissolution of acid‐gases in water are included. Steam‐assisted gravity drainage (SAGD) is also simulated for comparison. Results show that gas generation negatively impacts SAGD. However, in electrical heating dissolution of gases into solvent weakens their negative impact. Results indicate that SAGD generates a larger gas volume than electrical heating. In both processes, methane is found to be the major species in the produced gas and H2S concentration can reach high values. While the effect of acid–gas solubility in water on oil recovery is not evident its effect on generated gas volume is significant. Simulation results demonstrate that electrical heating is more energy efficient than SAGD. These results find application in design of experiments and pilot and field‐scale implementation of the process. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4243–4258, 2017 相似文献
12.
Gary G. Adams Shahwar Imran Sheng Wang Abubaker Mohammad M. Samil Kok David A. Gray Guy A. Channell Stephen E. Harding 《Food chemistry》2012
Pumpkin, a member of the Cucurbitaceae family has been used frequently as functional medicines for therapeutic use. Several phytochemicals such as polysaccharides, phenolic glycosides, 13-hydroxy-9Z, 11E-octadecatrienoic acid from the leaves of pumpkin, proteins from germinated seeds, have been isolated. 相似文献
13.
Harding CR Watkinson A Rawlings AV Scott IR 《International journal of cosmetic science》2000,22(1):21-52
The process leading to the loss of corneocytes form the skin surface is termed desquamation. In healthy skin it is an orderly and essentially invisible process whereby individual or small groups of corneocytes detach from neighbouring cells to be lost to the environment and replaced by younger cells from the deeper layers. Desquamation is carefully controlled to ensure that corneum cohesion and integrity, and hence tissue thickness, is maintained. The most important components of the corneocytes contributing towards intercellular cohesion are the corneodesmosomes and lipids. Corneodesmosomes are proteinaceous complexes which effectively rivet corneocytes together. The intercellular lipids, primarily responsible for the water barrier, also provide part of the extracellular cement. In addition, the shape of the corneocyte itself plays a role in stratum corneum cohesion. Through interdigitation along their peripheral edges, adjacent corneocytes become physically locked together, a process which reinforces the integrity of the tissue. For effective desquamation to occur corneodesmosomes must be degraded: a process catalysed by serine proteases present within the intercellular space and facilitated by subtle changes in lipid composition and phase behaviour. Ultimately, it is the availability of free water which controls corneodesmolysis. In healthy skin this proteolytic process leaves relatively few corneodesmosomes intact in the most superficial layers. By contrast, in chronic and acute dry skin conditions, corneodesmosomal degradation and hence the final stages of desquamation are perturbed, leading to the characteristic formation of visible, powdery flakes on the skin surface. The inability to degrade these structures ultimately reflects a decreased hydrolytic activity of the desquamatory enzymes, either through reduced synthesis of the enzymes, inherent loss of activity, leaching from the surface layers of the corneum or changes in the surrounding lipid-rich microenvironment, which may indirectly reduce enzyme functionality. Increased understanding of the desquamation process is providing new insights into the mode of action of current moisturizing ingredients and is offering opportunities to develop novel therapies for preventing and correcting dry skin. 相似文献
14.
Protecting against corner impacts: sensitivities discovered during a rail cask impact limiter design
D. C. Harding D. Garrido. Quevedo 《Packaging, Transport, Storage and Security of Radioactive Material》2014,25(1):38-46
Type B packages for the transportation of radioactive materials must remain ‘essentially leak tight’ under severe regulatory accident conditions, defined in the US Nuclear Regulatory Commission’s 10 CFR 71·73 and the International Atomic Energy Agency’s TS-R-1. The 9-m free drop test requirement onto an unyielding surface is performed in an orientation ‘for which maximum damage is expected’. Analytical techniques are used to evaluate various possible impact orientations before testing, and historically these maximal damage orientations have been side, slap-down, end, and centre-of-gravity over corner. Other orientations are rarely considered. Sandia National Laboratories (SNL) was asked by Equipos Nucleares SA (ENSA) to design, analyse, and test an impact limiter system for a newly designed rail cask. During the conceptual design process, SNL performed due diligence and evaluated a wide spectrum of possible impact orientations, in order to assure that peak cask body acceleration design goals were not exceeded. However, design of the impact limiter, including not only crush strength of constituent materials (which can be orientation and temperature dependent), but also the shape of the impact limiter, greatly affects peak acceleration response during 9-m drops in various orientations. Although many impact limiter design shapes resemble truncated right circular cylinders attached to each end of the cask, some tend to round the outer corners or truncate those corners with conical sections. SNL’s original conceptual design followed a similar theme, intending to use polyurethane foam or aluminium honeycomb within a bevelled corner shaped cylindrical shell. Detailed finite element analyses indicated excellent impact resistance at regulatory cold temperatures in the stereotypically tested side, slap-down, end, and CGOC impact orientations. Shortly before proceeding to engineering design, a rarely-considered impact orientation of 45° from horizontal indicated that cask body acceleration levels jumped unexpectedly, exceeding the design goal due to insufficient crushable material protecting the sharp corner of the cask. A complete re-design of the impact limiter was necessary, and the lessons learned from this experience could have implications for future impact limiter designs, and possibly existing designs that may not have considered this atypical impact orientation during the design process. 相似文献
15.
J. Benziger L. Cadonati F. Calaprice M. Chen A. Corsi F. Dalnoki-Veress R. Fernholz R. Ford C. Galbiati A. Goretti E. Harding Aldo Ianni Andrea Ianni S. Kidner M. Leung F. Loeser K. McCarty D. McKinsey A. Nelson A. Pocar C. Salvo D. Schimizzi T. Shutt A. Sonnenschein 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2009,608(3):464-474
The system for controlled filling of the nested flexible scintillator containment vessels in the Borexino solar neutrino detector is described. The design and operation principles of pressure and shape monitoring systems are presented for gas filling, gas displacement by water, and water displacement by scintillator. System specifications for safety against overstressing the flexible nylon vessels are defined as well as leak-tightness and cleanliness requirements. The fluid-filling system was a major engineering challenge for the Borexino detector. 相似文献
16.
Pulsed field gradient (PFG) nuclear magnetic resonance (NMR) and microimaging experiments have been performed to study the diffusion of liquid alkanes into a variety of semicrystalline polyethylene (PE) samples. The results highlight the importance of the crystalline phase in controlling the diffusion process in terms of both the geometric impedance imposed by the presence of impenetrable crystals and their effect on the mobility of the polymer chains comprising the amorphous material through which the penetrants migrate. 相似文献
17.
NR Powe RI Griffiths AJ Watson GF Anderson G de Lissovoy JW Greer RJ Herbert RA Milam PK Whelton 《Canadian Metallurgical Quarterly》1994,4(7):1455-1465
To examine the effects of recombinant human erythropoietin (rHuEPO) on hospital utilization, hospital costs, and Medicare reimbursements for hospital care, a longitudinal, matched cohort study was conducted using Medicare claims data of 23,806 Medicare-eligible, dialysis patients who received rHuEPO, did not have a transplant, and were alive for 18 mo or longer and 22,720 controls matched on age, sex, race, cause of ESRD, and dialysis modality. The relative odds (rHuEPO versus control) of admission for all causes and for specific causes over 9 mo, adjusted for admission in the prior 9 mo and the per patient change in total admissions, inpatient days, hospital costs, and Medicare hospital payments between the prior 9-mo period and the subsequent 9-mo period was examined. The adjusted relative odds (95% confidence interval) of admission (rHuEPO versus control) was: higher and statistically significant for all causes, 1.08 (1.03 to 1.14); seizure, 1.52 (1.28 to 1.75); vascular access revision, 1.11 (1.06 to 1.17), and heart failure, 1.17 (1.09 to 1.26); higher but not statistically significant for angina, 1.09 (0.99 to 1.20) and stroke, 1.08 (0.86 to 1.31); and lower but not statistically significant for myocardial infarction, 0.91 (0.72 to 1.10); peripheral vascular disease, 0.81 (0.60 to 1.02); anemia, 0.86 (0.56 to 1.17); and depression, 0.89 (0.37 to 1.40). The mean change per 1,000 patients in admissions was less by 38 (P = 0.03) because of fewer readmissions, and in days was 1,309 less (P < 0.001), for patients treated with rHuEPO versus controls. The mean change per patient in hospital costs was $371 less and was statistically significant (P = 0.03) and in Medicare hospital payments was $132 less but was not statistically significant (P = 0.43) for patients treated with rHuEPO versus controls. rHuEPO was associated with an increase in the probability of hospital admission (particularly admissions potentially related to adverse effects) but a decrease in readmissions, overall admissions, hospital days, and cost to hospitals in this cohort of patients surviving for 18 mo. Although not realized short term, Medicare savings from potential rHuEPO-related reductions in hospital care may be long term through future adjustments in diagnosis-related group-based hospital payment. 相似文献
18.
19.
Journal of Materials Science - A brief review is given of techniques which have been employed in attempts to determine the mechanical properties of composite materials under tensile impact loading.... 相似文献
20.
A case of a retained gallstone in the common bile duct after cholecystectomy (in a 38-year old man) is reported in which infusions with saline and spasmolytics failed to flush out the retained stone into the duodenum. An infusion with sodium cholate over nine days through the T-tube was successful in dissolution of the radiolucent stone. 相似文献