全文获取类型
收费全文 | 855篇 |
免费 | 139篇 |
国内免费 | 47篇 |
专业分类
电工技术 | 37篇 |
综合类 | 92篇 |
化学工业 | 226篇 |
金属工艺 | 11篇 |
机械仪表 | 33篇 |
建筑科学 | 81篇 |
矿业工程 | 153篇 |
能源动力 | 92篇 |
轻工业 | 47篇 |
水利工程 | 35篇 |
石油天然气 | 34篇 |
武器工业 | 8篇 |
无线电 | 13篇 |
一般工业技术 | 80篇 |
冶金工业 | 33篇 |
原子能技术 | 23篇 |
自动化技术 | 43篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 18篇 |
2019年 | 27篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 32篇 |
2015年 | 32篇 |
2014年 | 61篇 |
2013年 | 59篇 |
2012年 | 79篇 |
2011年 | 86篇 |
2010年 | 45篇 |
2009年 | 53篇 |
2008年 | 41篇 |
2007年 | 56篇 |
2006年 | 46篇 |
2005年 | 40篇 |
2004年 | 45篇 |
2003年 | 42篇 |
2002年 | 28篇 |
2001年 | 36篇 |
2000年 | 29篇 |
1999年 | 16篇 |
1998年 | 8篇 |
1997年 | 15篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1041条查询结果,搜索用时 15 毫秒
1.
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
2.
The dynamics of a thin liquid film falling down a uniformly heated wall is studied. The model introduced by Kalliadasis et al. [J. Fluid Mech. 475 (2003) 377] for the same problem is revisited and its deficiencies, namely the prediction of a critical
Reynolds number with 20% error, cured. For the energy equation a high-order Galerkin projection in terms of polynomial test
functions is developed. It is shown that not only does this more refined formulation correct the critical Reynolds number,
but it also gives, with an appropriate expansion close to criticality, the long-wave theory. Bifurcation diagrams for permanent
solitary waves are constructed and compared with the solution branches obtained from different models. It is shown that, in
all cases, the long-wave theory exhibits limit points and branch multiplicity, while the other models predict the continuing
existence of solitary waves. Time-dependent computations show that the free surface and interfacial temperature approach a
train of coherent structures that resemble the infinite-domain stationary solitary pulses. 相似文献
3.
Bedich ika Helena Bendov Ivan Macha
《Chemical Engineering and Processing: Process Intensification》2005,44(12):1312-1319
A procedure has been proposed for the estimation of the terminal falling velocity of non-spherical particles moving in a Carreau model fluid in the transition flow region. The procedure is based on a modification of the relationship formerly developed for the fall of spherical particles including the particle dynamic shape factor. The suitability of the proposed procedure has been confirmed by good agreement between experimental and calculated terminal falling velocity data. In the experiments, the terminal falling velocity of short cylinders and rectangular prisms in polymer solutions of different measure of shear thinning and elasticity has been measured. 相似文献
4.
5.
6.
肖炳荣 《现代塑料加工应用》2003,15(5):32-34
从型材内筋壁厚、加工助剂、辅助原料、塑化控制、模具流道等方面分析了PVC型材低温落锤破裂影响因素,并提出了提高PVC型材低温落锤冲击性能的建议。 相似文献
7.
8.
Heat transfer characteristics for a falling turbulent liquid film flow over a fin are analyzed using the conjugate convection-conduction theory. Numerical results are obtained from a simultaneous solution of the energy equations of the fluid and the fin. Results are presented for the fin temperature distribution, dimensionless heat transfer coefficients, local heat fluxes, and fin efficiencies. 相似文献
9.
10.