全文获取类型
收费全文 | 864篇 |
免费 | 33篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 149篇 |
金属工艺 | 6篇 |
机械仪表 | 7篇 |
建筑科学 | 39篇 |
矿业工程 | 3篇 |
能源动力 | 41篇 |
轻工业 | 140篇 |
水利工程 | 10篇 |
石油天然气 | 20篇 |
无线电 | 60篇 |
一般工业技术 | 109篇 |
冶金工业 | 216篇 |
原子能技术 | 5篇 |
自动化技术 | 86篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 23篇 |
2016年 | 23篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 34篇 |
2012年 | 43篇 |
2011年 | 46篇 |
2010年 | 53篇 |
2009年 | 22篇 |
2008年 | 39篇 |
2007年 | 37篇 |
2006年 | 35篇 |
2005年 | 29篇 |
2004年 | 23篇 |
2003年 | 20篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 19篇 |
1998年 | 61篇 |
1997年 | 26篇 |
1996年 | 25篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 15篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1966年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有897条查询结果,搜索用时 15 毫秒
71.
We have presented an empirical model for predicting the viscosity of binary mixtures of gases, based on our previous correlation for natural gas mixtures (Miadonye and Clyburn, 2003). New parameters were derived for binary mixtures of carbon monoxide-noble gases and for carbon monoxide-nitrogen gases, for temperatures from 0-1000°C. The model was validated with the Chapman-Enskog equation for gas mixtures, with and without length scaling factor. For five equimolar and eight non-equimolar mixtures of gases at temperatures from 0-1000°C, the model gave an excellent viscosity prediction with an overall average absolute deviation of 0.45%. The model is simple to incorporate in design and simulation packages, and more accurate than any correlation currently used for estimating the viscosities of gas mixtures. 相似文献
72.
Initiatives towards large-scale dissemination of solar dryers for drying of agri-produce face severe competition from the largely prevalent practice of open sun drying in most of the developing countries. Therefore, solar drying systems must offer exceptionally attractive financial gains to enhance their acceptance among the potential users. A modest attempt to develop a simple framework to facilitate a comparison of the financial feasibility of solar drying as against open sun drying has been made in the present work. Results of some exemplifying calculations are presented and briefly discussed. 相似文献
73.
We hypothesized that an in vitro bioartificial skin rejection model using living LSEs grown in tissue culture could be developed for the study of autologous, allogenic, and/or xenogeneic inflammatory/immune mechanisms and topical immunosuppressive drugs. Human fibroblasts were mixed with type 1 rat-tail collagen to form a matrix (4 to 5 days), on which human keratinocytes were seeded. After a keratinocyte monolayer formed, CT cultures were raised to the air-liquid interface for continued growth. In the REJ LSE model, immunocytes isolated from human blood were seeded on top of the NHEK monolayer at the time of air-lifting. Thickness measurements of the acellular keratin and keratinocyte layers, and nuclear/cytoplasmic ratios, in both CT and REJ were made using digital image analysis. Immunostaining with anticytokeratin demonstrated a viable, keratin-producing epidermal layer; staining with anti-TGF-beta suggested a role for this cytokine in the rejection or wound-healing process. The LSE appeared histologically similar to normal human epidermis. Immunocytes added to the REJ cultures caused an obvious rejection response and were clearly identifiable in the gels as CD45+ staining cells. The LSE model appears promising for the study of immune/inflammatory mechanisms, thermal injury, screening antirejection agents that might be applied topically and as an in vitro replacement for skin graft studies in animals. 相似文献
74.
A financial analysis of biomass briquetting technology in India has been undertaken. Simple cost functions for briquetting machines have been developed. Unit cost of briquette production for various types of raw materials and different capacities of briquetting units have been calculated. Role of different factors affecting the cost of production of briquettes have also been analysed. 相似文献
75.
Karen Foley 《Landscape Research》2014,39(4):359-386
AbstractHousing development in rural localities represents one of the most visible and contested indicators of landscape change, as many European rural landscapes that are regulated by weak planning regimes are transformed by incremental suburbanisation. However, scant attention has been given to understanding stakeholder perceptions and interpretations of the physical processes of landscape change and preferences towards accommodating new housing development in rural areas among stakeholder groups. We address this deficit by drawing on a series of stakeholder focus groups undertaken in Ireland addressing: 1) stakeholder perceptions of landscape change and 2) attitudes towards future change scenarios based on digitally manipulated images of landscape change. The focus group analysis suggests a nuanced interpretation among rural residents of the impact of accommodating housing development, particularly in balancing local demand for rural housing with preferences for maintaining a sense of ‘rural character’; however, there were variations across rural space dependant on the extent of development experienced in recent years. 相似文献
76.
Robert N. Foley Craig A. Solid Kenneth Lamb 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):24-31
Anemia management in hemodialysis patients is of primary importance for clinicians and dialysis providers. Through a retrospective claims analysis, we studied prevalent US hemodialysis patients 1998–2009, and examined patterns of hemoglobin levels and erythropoiesis‐stimulating agent (ESA, epoetin [EPO], and darbepoetin [DPO] ) doses surrounding hospitalization events. Medicare outpatient claims were used to determine monthly ESA doses and associated hemoglobin levels. ESA dose trajectories were defined with repeated measures models incorporating an autoregressive covariance matrix that compared subsequent measurements with the index month of hospitalization, with variance component covariance matrices chosen for pair‐wise comparisons. Regarding prehospitalization hemoglobin levels, a biphasic pattern occurred in both the EPO (1998–2009, n = 161,242) and DPO (2004–2009, n = 4391) populations; levels rose from 1998 to 2004, fell thereafter in the EPO population, and fell after 2006 or 2007 in the DPO population. In the EPO population, the proportions of patients with hemoglobin less than 10 g/dL were 30.1% in 1998, 14.5% in 2004, and 28.3% in 2009; corresponding values for the DPO population were 21.0% in 2004 and 31.6% in 2009. While some degree of year‐to‐year variability occurred, EPO dose trends were less pronounced, with an apparent peak in 2004 followed by a modest decline; trends were similar for DPO. Trends in EPO dose trajectories did not completely parallel those for hemoglobin level; while EPO doses increased yearly up to 2004, doses stabilized, but did not materially decrease after 2004. No definite annual trends for DPO dose trajectories were apparent. 相似文献
77.
78.
Mild RM Joens LA Friedman M Olsen CW McHugh TH Law B Ravishankar S 《Journal of food science》2011,76(3):M163-M168
Abstract: Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multidrug resistant. Apple‐based edible films containing carvacrol and cinnamaldehyde were evaluated for bactericidal activity against antibiotic resistant and susceptible C. jejuni strains on chicken. Retail chicken breast samples inoculated with D28a and H2a (resistant strains) and A24a (a sensitive strain) were wrapped in apple films containing cinnamaldehyde or carvacrol at 0.5%, 1.5%, and 3% concentrations, and then incubated at 4 or 23 °C for 72 h. Immediately after wrapping and at 72 h, samples were plated for enumeration of viable C. jejuni. The antimicrobial films exhibited dose‐ and temperature‐dependent bactericidal activity against all strains. Films with ≥1.5% cinnamaldehyde reduced populations of all strains to below detection at 23 °C at 72 h. At 4 °C with cinnamaldehyde, reductions were variable for all strains, ranging from 0.2 to 2.5 logs and 1.8 to 6.0 logs at 1.5% and 3.0%, respectively. Films with 3% carvacrol reduced populations of A24a and H2a to below detection, and D28a by 2.4 logs at 23 °C and 72 h. A 0.5‐log reduction was observed for both A24a and D28a, and 0.9 logs for H2a at 4 °C at 3% carvacrol. Reductions ranged from 1.1 to 1.9 logs and 0.4 to 1.2 logs with 1.5% and 0.5% carvacrol at 23 °C, respectively. The films with cinnamaldehyde were more effective than carvacrol films. Reductions at 23 °C were greater than those at 4 °C. Our results showed that antimicrobial apple films have the potential to reduce C. jejuni on chicken and therefore, the risk of campylobacteriosis. Possible mechanisms of antimicrobial effects are discussed. Practical Application: Apple antimicrobial films could potentially be used in retail food packaging to reduce C. jejuni commonly present on food. 相似文献
79.
Jia Du A. D. Hellicar S. M. Hanham L. Li J. C. Macfarlane K. E. Leslie C. P. Foley 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(5):681-690
A high-Tc superconducting (HTS) broadband Josephson detector has been developed and applied to millimetre wave (mm-wave) and terahertz
(THz) imaging. The detector is based on a YBa2Cu3O7-x (YBCO) step-edge Josephson junction, which is coupled to a thin-film log-periodic antenna, designed for operation at 200–600 GHz,
and a hemispheric silicon lens. The junction parameters have been optimised to achieve a high IcRn value so that the detector responds well to the specified frequencies at liquid nitrogen temperature (77 K). Images at ∼200 GHz
and ∼600 GHz were acquired with the same detector; each demonstrated their unique properties. The results demonstrate the
potential of achieving a cheaper, compact and portable multi-spectral imager based on a HTS detector. 相似文献
80.
Wu TH Teslaa T Kalim S French CT Moghadam S Wall R Miller JF Witte ON Teitell MA Chiou PY 《Analytical chemistry》2011,83(4):1321-1327
It is difficult to achieve controlled cutting of elastic, mechanically fragile, and rapidly resealing mammalian cell membranes. Here, we report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized explosive vapor bubble, which rapidly punctures a lightly contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The cavitation bubble pattern is controlled by the metallic structure configuration and laser pulse duration and energy. Integration of the metallic nanostructure with a micropipet, the nanoblade generates a micrometer-sized membrane access port for delivering highly concentrated cargo (5 × 10(8) live bacteria/mL) with high efficiency (46%) and cell viability (>90%) into mammalian cells. Additional biologic and inanimate cargo over 3-orders of magnitude in size including DNA, RNA, 200 nm polystyrene beads, to 2 μm bacteria have also been delivered into multiple mammalian cell types. Overall, the photothermal nanoblade is a new approach for delivering difficult cargo into mammalian cells. 相似文献