全文获取类型
收费全文 | 2920篇 |
免费 | 101篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 3024篇 |
出版年
2023年 | 11篇 |
2021年 | 26篇 |
2020年 | 32篇 |
2019年 | 39篇 |
2018年 | 52篇 |
2017年 | 45篇 |
2016年 | 51篇 |
2015年 | 37篇 |
2014年 | 53篇 |
2013年 | 139篇 |
2012年 | 111篇 |
2011年 | 165篇 |
2010年 | 100篇 |
2009年 | 113篇 |
2008年 | 138篇 |
2007年 | 140篇 |
2006年 | 112篇 |
2005年 | 111篇 |
2004年 | 98篇 |
2003年 | 76篇 |
2002年 | 78篇 |
2001年 | 56篇 |
2000年 | 39篇 |
1999年 | 54篇 |
1998年 | 179篇 |
1997年 | 105篇 |
1996年 | 85篇 |
1995年 | 64篇 |
1994年 | 55篇 |
1993年 | 41篇 |
1992年 | 37篇 |
1991年 | 39篇 |
1990年 | 30篇 |
1989年 | 40篇 |
1988年 | 32篇 |
1987年 | 39篇 |
1986年 | 31篇 |
1985年 | 27篇 |
1984年 | 25篇 |
1983年 | 28篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 21篇 |
1979年 | 18篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1976年 | 65篇 |
1975年 | 21篇 |
1974年 | 11篇 |
1973年 | 16篇 |
排序方式: 共有3024条查询结果,搜索用时 31 毫秒
1.
Macintosh Katrina A. McDowell Richard W. Wright-Stow Aslan E. Depree Craig Robinson Guy M. 《Nutrient Cycling in Agroecosystems》2021,120(2):121-129
Nutrient Cycling in Agroecosystems - Reducing agriculturally derived diffuse contaminant losses (via non-point sources) from land to water has proven difficult for decades. Owing to the diversity... 相似文献
2.
Yang Hu Stephanie M. Sjoberg Chunpen Chen Amber L. Hauvermale Craig F. Morris Stephen R. Delwiche Ashley E. Cannon Camille M. Steber Zhiwu Zhang 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2105-2117
This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging. 相似文献
3.
Eco-driving has been proposed as an approach to significantly reduce greenhouse gas emissions arising from personal automobile use. Eco-driving is the adoption of a measured driving style, minimising unnecessary breaking and aggressive acceleration. Eco-driving can be seen as a low cost and immediate approach to emission reduction as it involves the modification of drivers’ behaviours as opposed to the development and implementation of newer, more efficient technology. Despite the proposed benefits of eco-driving, numerous challenges are faced in order to encourage the adoption of these behaviours and maintain them long term. This narrative review presents the concept of eco-driving, with a focus on the long-term maintenance of these behaviours, including training programmes and feedback devices. It is clear within current literature that, despite the economic and environmental benefits of adopting eco-driving, drivers require feedback on their actions in order to promote long-term, behavioural, change. 相似文献
4.
Ashim Gupta Craig Cady Anne-Marie Fauser Hugo C. Rodriguez R. Justin Mistovich Anish G. R. Potty Nicola Maffulli 《International journal of molecular sciences》2020,21(24)
Stem cells for regenerative medicine purposes offer therapeutic benefits, but disadvantages are still ill defined. The benefit of stem cells may be attributed to their secretion of growth factors (GFs), cytokines (CKs), and extracellular vesicles (EVs), including exosomes. We present a novel cell-free stem cell-derived extract (CCM), formulated from human progenitor endothelial stem cells (hPESCs), characterized for biologically active factors using ELISA, nanoparticle tracking analysis and single particle interferometric reflectance imaging sensing. The effect on fibroblast proliferation and ability to induce stem cell migration was analyzed using Alamar Blue proliferation and Transwell migration assays, respectively. GFs including IGFBP 1, 2, 3, and 6, insulin, growth hormone, PDGF-AA, TGF-α, TGF-β1, VEGF, and the anti-inflammatory cytokine, IL-1RA were detected. Membrane enclosed particles within exosome size range and expressing exosome tetraspanins CD81 and CD9 were identified. CCM significantly increased cell proliferation and induced stem cell migration. Analysis of CCM revealed presence of GFs, CKs, and EVs, including exosomes. The presence of multiple factors including exosomes within one formulation, the ability to promote cell proliferation and induce stem cell migration may reduce inflammation and pain, and augment tissue repair. 相似文献
5.
6.
7.
8.
Clíona Rooney Karim Hadjri Keith Mcallister Máirín Rooney Verity Faith Cathy Craig 《Journal of Housing and the Built Environment》2018,33(1):45-67
Lifetime home standards (LTHS) are a set of standards aimed at making homes more accessible. Previous research, however, indicates that LTHS do not adequately meet the needs of those with sensory impairments. Now, with visual impairment set to increase globally and acknowledging the recognised link between quality of dwelling and wellbeing, this article aims to examine the experiences of visually impaired people living in lifetime homes. The objectives are to investigate existing lifetime homes and to identify whether LTHS meet occupants’ needs. Qualitative semi-structured interviews were carried out with six visually impaired people living in homes designed to LTHS in Northern Ireland. Collected data was analysed using interpretative phenomenological analysis identifying three super-ordinate themes: (1) living with visual impairment; (2) design considerations and (3) coping strategies. A core theme of balance between psychological and physical needs emerged through interconnection of super-ordinate themes. Although there are benefits to living in lifetime homes, negative aspects are also apparent with occupants employing several coping strategies to overcome difficulties. Whilst residents experience negative emotions following visual impairment diagnoses, results suggest that occupants still regard their homes as key places of security and comfort in addition to then highlighting the need for greater consideration of specific individual needs within general guidelines. 相似文献
9.
Cunkui Huang Craig Hawrelechko James Donald Haibo Huang Xiaohui Deng 《American Institute of Chemical Engineers》2020,66(8):e16265
Solvent mass transfer plays a key role in a thermal gravity drainage process involving solvent. The diffusion coefficients of solvent in such a process are not well studied. This article presents the effective diffusion coefficients of solvent in bitumen-saturated sands under high temperature/pressure conditions measured using a CT scanning technique. Experimental results show that the effective diffusion coefficient of n-hexane in bitumen-saturated sands varied with the solvent concentration or with the viscosity of solvent–bitumen mixture (i.e., De ∝ c0.4 or De ∝ μm−0.46). The solvent concentration weighted diffusion coefficient of n-hexane in the bitumen under the condition 160–170°C/1,900 kPa had an order of magnitude of about 10−5 cm2/s for solvent volume concentration less than 0.2. The penetration distance of n-hexane in bitumen-saturated sands depended on the nonlinearity of diffusion and had a value of −2 cm after 1-day diffusion. The stronger the nonlinearity of diffusion, the shorter the penetration distance. 相似文献