全文获取类型
| 收费全文 | 1306篇 |
| 免费 | 34篇 |
| 国内免费 | 3篇 |
专业分类
| 电工技术 | 9篇 |
| 综合类 | 3篇 |
| 化学工业 | 235篇 |
| 金属工艺 | 25篇 |
| 机械仪表 | 27篇 |
| 建筑科学 | 52篇 |
| 矿业工程 | 1篇 |
| 能源动力 | 55篇 |
| 轻工业 | 134篇 |
| 水利工程 | 14篇 |
| 石油天然气 | 2篇 |
| 无线电 | 81篇 |
| 一般工业技术 | 285篇 |
| 冶金工业 | 268篇 |
| 原子能技术 | 16篇 |
| 自动化技术 | 136篇 |
出版年
| 2024年 | 7篇 |
| 2023年 | 17篇 |
| 2022年 | 23篇 |
| 2021年 | 40篇 |
| 2020年 | 31篇 |
| 2019年 | 41篇 |
| 2018年 | 48篇 |
| 2017年 | 41篇 |
| 2016年 | 43篇 |
| 2015年 | 26篇 |
| 2014年 | 52篇 |
| 2013年 | 61篇 |
| 2012年 | 76篇 |
| 2011年 | 73篇 |
| 2010年 | 52篇 |
| 2009年 | 40篇 |
| 2008年 | 40篇 |
| 2007年 | 39篇 |
| 2006年 | 27篇 |
| 2005年 | 27篇 |
| 2004年 | 22篇 |
| 2003年 | 22篇 |
| 2002年 | 24篇 |
| 2001年 | 14篇 |
| 2000年 | 12篇 |
| 1999年 | 21篇 |
| 1998年 | 56篇 |
| 1997年 | 52篇 |
| 1996年 | 29篇 |
| 1995年 | 18篇 |
| 1994年 | 16篇 |
| 1993年 | 24篇 |
| 1992年 | 17篇 |
| 1991年 | 13篇 |
| 1990年 | 10篇 |
| 1989年 | 16篇 |
| 1988年 | 13篇 |
| 1987年 | 6篇 |
| 1986年 | 6篇 |
| 1985年 | 8篇 |
| 1984年 | 10篇 |
| 1983年 | 10篇 |
| 1982年 | 7篇 |
| 1981年 | 6篇 |
| 1980年 | 9篇 |
| 1979年 | 11篇 |
| 1977年 | 13篇 |
| 1976年 | 13篇 |
| 1975年 | 12篇 |
| 1968年 | 9篇 |
排序方式： 共有1343条查询结果，搜索用时 15 毫秒
991.
Skeletal mechanism generation for surrogate fuels using directed relation graph with error propagation and sensitivity analysis 总被引：1，自引：0，他引：1
A novel implementation for the skeletal reduction of large detailed reaction mechanisms using the directed relation graph with error propagation and sensitivity analysis (DRGEPSA) is developed and presented with examples for three hydrocarbon components, n-heptane, iso-octane, and n-decane, relevant to surrogate fuel development. DRGEPSA integrates two previously developed methods, directed relation graph-aided sensitivity analysis (DRGASA) and directed relation graph with error propagation (DRGEP), by first applying DRGEP to efficiently remove many unimportant species prior to sensitivity analysis to further remove unimportant species, producing an optimally small skeletal mechanism for a given error limit. It is illustrated that the combination of the DRGEP and DRGASA methods allows the DRGEPSA approach to overcome the weaknesses of each, specifically that DRGEP cannot identify all unimportant species and that DRGASA shields unimportant species from removal. Skeletal mechanisms for n-heptane and iso-octane generated using the DRGEP, DRGASA, and DRGEPSA methods are presented and compared to illustrate the improvement of DRGEPSA. From a detailed reaction mechanism for n-alkanes covering n-octane to n-hexadecane with 2115 species and 8157 reactions, two skeletal mechanisms for n-decane generated using DRGEPSA, one covering a comprehensive range of temperature, pressure, and equivalence ratio conditions for autoignition and the other limited to high temperatures, are presented and validated. The comprehensive skeletal mechanism consists of 202 species and 846 reactions and the high-temperature skeletal mechanism consists of 51 species and 256 reactions. Both mechanisms are further demonstrated to well reproduce the results of the detailed mechanism in perfectly-stirred reactor and laminar flame simulations over a wide range of conditions. The comprehensive and high-temperature n-decane skeletal mechanisms are included as supplementary material with this article. 相似文献
992.
Earlier emf data on cells using the PbSO4/Pb(Hg) electrode have been used, in conjunction with a recent determination of the standard potential of this electrode, to calculate stoichiometric activity coefficients of H2SO4 in water at 298·15°K. 相似文献
993.
Ahmed Gadelmawla Udo Eckstein Kevin Riess Yi-Xuan Liu Ke Wang Jing-Feng Li Ken-ichi Kakimoto Neamul H. Khansur Kyle G. Webber 《Journal of the American Ceramic Society》2023,106(4):2326-2337
The influence of stress on the small-signal dielectric permittivity and piezoelectric coefficient of polycrystalline lead-free perovskite 0.92(Na1/2K1/2)NbO3–(0.08 − x)Bi1/2Li1/2TiO3–xBaZrO3 (x = 0, 0.02, 0.04, 0.06, and 0.07) was characterized under different constant uniaxial stress up to −200 MPa within a temperature range of −150 to 450°C, revealing stress-induced suppression of the electromechanical response as well as shifts in the phase boundaries. For all compositions, the interferroelectric and ferroelectric–paraelectric phase transitions were shifted to higher temperatures under the uniaxial compressive stress. Interestingly, the sensitivity to the applied stress was found to increase with increasing BZ/BLT ratio in the system. The origin of a different extent of stress-sensitivity with BZ/BLT ratio is suggested to be related to the change in the crystal structure. Additionally, at temperatures below −50°C, the relative permittivity showed a significant increase under applied compressive stress. 相似文献
994.
Adam E. Jakus Monica M. Laronda Alexandra S. Rashedi Christina M. Robinson Chris Lee Sumanas W. Jordan Kyle E. Orwig Teresa K. Woodruff Ramille N. Shah 《Advanced functional materials》2017,27(34)
Using an innovative, tissue‐independent approach to decellularized tissue processing and biomaterial fabrication, the development of a series of “tissue papers” derived from native porcine tissues/organs (heart, kidney, liver, muscle), native bovine tissue/organ (ovary and uterus), and purified bovine Achilles tendon collagen as a control from decellularized extracellular matrix particle ink suspensions cast into molds is described. Each tissue paper type has distinct microstructural characteristics as well as physical and mechanical properties, is capable of absorbing up to 300% of its own weight in liquid, and remains mechanically robust (E = 1–18 MPa) when hydrated; permitting it to be cut, rolled, folded, and sutured, as needed. In vitro characterization with human mesenchymal stem cells reveals that all tissue paper types support cell adhesion, viability, and proliferation over four weeks. Ovarian tissue papers support mouse ovarian follicle adhesion, viability, and health in vitro, as well as support, and maintain the viability and hormonal function of nonhuman primate and human follicle‐containing, live ovarian cortical tissues ex vivo for eight weeks postmortem. “Tissue papers” can be further augmented with additional synthetic and natural biomaterials, as well as integrated with recently developed, advanced 3D‐printable biomaterials, providing a versatile platform for future multi‐biomaterial construct manufacturing. 相似文献
995.
‘Sense of place’ is a fundamental, yet presumptive concept within the planning and design disciplines. Professional theories have largely remained focused on the physical aspects of place, as this is their primary mode of production. However, the academic literature suggests that sense of place is a multidimensional concept that extends beyond the physical attributes of a given location. A thorough literature review reveals that sense of place is influenced by four primary dimensions. It is argued that this theoretical perspective can better inform the transformation of space into place by linking each dimension with specific design processes. 相似文献
996.
997.
Kyle E. Fitch Keith D. Hutchison Kevin S. Bartlett Robert S. Wacker Kevin C. Gross 《International journal of remote sensing》2016,37(11):2604-2620
A system-level analysis has been completed to assess the accuracy of cloud base height (CBH) products of lower-altitude water clouds created from Visible Infrared Imaging Radiometer Suite (VIIRS) data collected by the National Aeronautics and Space Administration (NASA) Suomi National Polar-orbiting Partnership (S-NPP) and the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS). While the analysis focused on the CBH products, it necessarily included an assessment of other key, upstream VIIRS cloud products, including VIIRS cloud top height (CTH), VIIRS cloud optical thickness (COT), and VIIRS cloud effective particle size (EPS). The COT and EPS products are used to derive a geometric cloud thickness, which is then subtracted from the CTH product to generate the CBH product. Thus, a system-level analysis is critical to establishing the detailed algorithm error budget needed to identify the major sources of errors in the CBH product and help focus future research efforts to improve this important cloud product. As a consequence, ground-based data collected at the US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) sites became most useful for conducting this system-level analysis. Therefore, match-up data sets were created between VIIRS cloud products and DOE ARM site data sets from June 2013 to October 2015, and while the primary focus was on the highest-quality data at the Lamont, OK ARM site, data were analysed from a total of four ARM sites. The initial results showed the errors in the VIIRS CBH products, compared to the ARM site data sets, to be large and highly variable; however, errors in VIIRS COT and the derived VIIRS cloud geometric thickness were much smaller. Consequently, the VIIRS CTH products were replaced with the ARM CTH products, which substantially reduced the variability and errors in the VIIRS CBH products. It is concluded that the performance of the VIIRS CBH products is most strongly correlated with errors in the VIIRS CTH products, while errors in COT and geometric cloud thicknesses are acceptable. Thus, future research is needed to reduce the errors in the VIIRS CTH products in order to ensure the VIIRS CBH products are suitable for civilian and military aerodrome operations. 相似文献
998.
Kyle H. Vining Jacob C. Scherba Alaina M. Bever Morgan R. Alexander Adam D. Celiz David J. Mooney 《Advanced materials (Deerfield Beach, Fla.)》2018,30(4)
Dental disease annually affects billions of patients, and while regenerative dentistry aims to heal dental tissue after injury, existing polymeric restorative materials, or fillings, do not directly participate in the healing process in a bioinstructive manner. There is a need for restorative materials that can support native functions of dental pulp stem cells (DPSCs), which are capable of regenerating dentin. A polymer microarray formed from commercially available monomers to rapidly identify materials that support DPSC adhesion is used. Based on these findings, thiol‐ene chemistry is employed to achieve rapid light‐curing and minimize residual monomer of the lead materials. Several triacrylate bulk polymers support DPSC adhesion, proliferation, and differentiation in vitro, and exhibit stiffness and tensile strength similar to existing dental materials. Conversely, materials composed of a trimethacrylate monomer or bisphenol A glycidyl methacrylate, which is a monomer standard in dental materials, do not support stem cell adhesion and negatively impact matrix and signaling pathways. Furthermore, thiol‐ene polymerized triacrylates are used as permanent filling materials at the dentin‐pulp interface in direct contact with irreversibly injured pulp tissue. These novel triacrylate‐based biomaterials have potential to enable novel regenerative dental therapies in the clinic by both restoring teeth and providing a supportive niche for DPSCs. 相似文献
999.
F. I. Abam E. B. Ekwe T. A. Briggs S. O. Effiom O. S. Ohunakin M. Allen 《国际自然能源杂志》2018,39(4):332-342
1000.