全文获取类型
收费全文 | 469篇 |
免费 | 25篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 19篇 |
综合类 | 1篇 |
化学工业 | 142篇 |
金属工艺 | 6篇 |
机械仪表 | 21篇 |
建筑科学 | 18篇 |
能源动力 | 15篇 |
轻工业 | 54篇 |
水利工程 | 6篇 |
石油天然气 | 4篇 |
无线电 | 51篇 |
一般工业技术 | 91篇 |
冶金工业 | 28篇 |
原子能技术 | 6篇 |
自动化技术 | 36篇 |
出版年
2024年 | 3篇 |
2023年 | 6篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 27篇 |
2017年 | 17篇 |
2016年 | 14篇 |
2015年 | 21篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 38篇 |
2011年 | 21篇 |
2010年 | 25篇 |
2009年 | 17篇 |
2008年 | 22篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有498条查询结果,搜索用时 734 毫秒
1.
Roselle Barretto Rania Marie Buenavista Jared Lou Rivera Shuyu Wang P.V. Vara Prasad Kaliramesh Siliveru 《International Journal of Food Science & Technology》2021,56(7):3125-3137
The demand for food production has been constantly increasing due to rising population. In developed countries, for example, the emergence of regional production of old grains that are rarely utilized, along with the production of commonly consumed grains, has gained importance in recent years. These grains, known collectively as ancient or heirloom grains, have offered both farmers and consumers novel ways of cultivation and products with interesting taste, characteristics and nutritional value. Among the 30 000 plant species known, only five cereals currently provide more than 50% of the world's energy intake – bread wheat (Triticum aestivum), rice (Oryza sativa), sorghum (Sorghum bicolor), millets (Panicum sp.) and maize (Zea mays). The excessive utilization of these selected species has a great potential to cause genetic losses and difficulty in bridging future agricultural demands. Teff (Eragrostis tef), an ancient grain extensively cultivated in countries like Eritrea and Ethiopia, provides promising alternatives for new food uses since its nutritional value is significantly higher than most others cereal grains. The absence of gluten allows flexibility in food utilization since it can be directly substituted to gluten-containing products. The grain also offers an excellent balance of essential amino acids and minerals, which can fulfil the recommended daily intake and eliminates the need for fortification and enrichment. This review provides a general overview of the physical properties and nutritional composition of teff grains related to processing and applications in the food and feed industries. The current status of teff utilization, as well as the challenges in production and commercialization, and future opportunities is presented and discussed. 相似文献
2.
Mahmoud M. Abou el Leil Frank A. Camaratta Rocco R. DiGenova 《Journal of the American Ceramic Society》1985,68(1):18-C-
In-service fracture of helicopter windshields was studied. Simulated catastrophic fracture tests were conducted by firing alumina and steel spheres onto stationary tempered and as-received glass panels. The results were studied by Hertzian analysis and modified Auerbach's relations. Thermally tempered glass shows much higher impact resistance than that estimated from superposition of residual stresses. Subcritical impact sites exhibit slow crack growth in tempered plates, eventually leading to fracture of the entire plate. 相似文献
3.
Rosenberg Florian Curbera Francisco Duftler Matthew J. Khalaf Rania 《Internet Computing, IEEE》2008,12(5):24-31
The use of RESTful Web services has gained momentum in the development of distributed applications based on traditional Web standards such as HTTP. In particular, these services can integrate easily into various applications, such as mashups. Composing RESTful services into Web-scale workflows requires a lightweight composition language that's capable of describing both the control and data flow that constitute a workflow. The authors address these issues with Bite, a lightweight and extensible composition language that enables the creation of Web-scale workflows and uses RESTful services as its main composable entities. 相似文献
4.
Abd El-Shafy A. Nafeh Faten H. Fahmy Essam M. Abou El-Zahab 《Solar Energy Materials & Solar Cells》2003,75(3-4):723-728
In this paper the implementation of a suggested stand-alone PV system, for maximum-power point tracking (MPPT), is carried out. Also, this paper presents a comparative study, through experimental work, between the conventional PI controller and the fuzzy logic controller (FLC) under different atmospheric conditions. The implemented system with both the PI controller and the FLC gives a good maximum-power operation of the PV array, but the tracking capability for different optimum operating points is better and faster for the case of using the FLC compared to the case of using the PI controller. 相似文献
5.
Lasserre S Hernando J Hill S Schümann F Anasagasti Pde M Jaoudé GA Markram H 《IEEE transactions on visualization and computer graphics》2012,18(2):214-227
We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons. 相似文献
6.
El Nahrawy Amany M. Hemdan Bahaa A. Abou Hammad Ali B. Othman Abdelmageed M. Abouelnaga Amal M. Mansour A. M. 《SILICON》2021,13(9):2979-2991
Silicon - Magnesium calcium silicate nanostructures (MCSNS) loaded with (0.0, 0.6, 0.9, and 1.2 wt%) of Cephradine-drug consisting of mesoporous particles were functionally prepared by sol-gel... 相似文献
7.
Kavitej Samra Mathun Kuganesan William Smith Anna Kleyman Robert Tidswell Nishkantha Arulkumaran Mervyn Singer Alex Dyson 《International journal of molecular sciences》2021,22(6)
Metabolically active gasotransmitters (nitric oxide, carbon monoxide and hydrogen sulfide) are important signalling molecules that show therapeutic utility in oxidative pathologies. The reduced form of selenium, hydrogen selenide (HSe−/H2Se), shares some characteristics with these molecules. The simple selenide salt, sodium hydroselenide (NaHSe) showed significant metabolic activity, dose-dependently decreasing ex vivo O2 consumption (rat soleus muscle, liver) and transiently inhibiting mitochondrial cytochrome C oxidase (liver, heart). Pharmacological manipulation of selenoprotein expression in HepG2 human hepatocytes revealed that the oxidation status of selenium impacts on protein expression; reduced selenide (NaHSe) increased, whereas (oxidized) sodium selenite decreased the abundance of two ubiquitous selenoproteins. An inhibitor of endogenous sulfide production (DL-propargylglycine; PAG) also reduced selenoprotein expression; this was reversed by exogenous NaHSe, but not sodium hydrosulfide (NaHS). NaHSe also conferred cytoprotection against an oxidative challenge (H2O2), and this was associated with an increase in mitochondrial membrane potential. Anesthetized Wistar rats receiving intravenous NaHSe exhibited significant bradycardia, metabolic acidosis and hyperlactataemia. In summary, NaHSe modulates metabolism by inhibition of cytochrome C oxidase. Modification of selenoprotein expression revealed the importance of oxidation status of selenium therapies, with implications for current clinical practice. The utility of NaHSe as a research tool and putative therapeutic is discussed. 相似文献
8.
Dr. Heike M. Kropp Dr. Samra Ludmann Dr. Kay Diederichs Dr. Karin Betz Dr. Andreas Marx 《Chembiochem : a European journal of chemical biology》2021,22(21):3060-3066
With increasing temperature, nucleobases in DNA become increasingly damaged by hydrolysis of exocyclic amines. The most prominent damage includes the conversion of cytosine to uracil and adenine to hypoxanthine. These damages are mutagenic and put the integrity of the genome at risk if not repaired appropriately. Several archaea live at elevated temperatures and thus, are exposed to a higher risk of deamination. Earlier studies have shown that DNA polymerases of archaea have the property of sensing deaminated nucleobases in the DNA template and thereby stalling the DNA synthesis during DNA replication providing another layer of DNA damage recognition and repair. However, the structural basis of uracil and hypoxanthine sensing by archaeal B-family DNA polymerases is sparse. Here we report on three new crystal structures of the archaeal B-family DNA polymerase from Thermococcus kodakarensis (KOD) DNA polymerase in complex with primer and template strands that have extended single stranded DNA template 5’-overhangs. These overhangs contain either the canonical nucleobases as well as uracil or hypoxanthine, respectively, and provide unprecedented structural insights into their recognition by archaeal B-family DNA polymerases. 相似文献
9.
In this paper, we discuss the design of a new Medium Access Control (MAC) protocol, SRI-MAC (Synchronous Receiver Initiated MAC), for wireless sensor networks whose goal is to extend the lifetime of the network by avoiding major energy waste causes, such as collisions, overhearing and idle listening. 相似文献
10.
A. Daoud M. T. Abou El-Khair A. N. Abdel-Azim 《Journal of Materials Engineering and Performance》2004,13(2):135-143
Aluminum (Al) alloy 7075 reinforced with Al2O3 particles was prepared using the stir casting method. The microstructure of the cast composites showed some degree of porosity
and sites of Al2O3 particle clustering, especially at high-volume fractions of Al2O3 particles. Different squeeze pressures (25 and 50 MPa) were applied to the cast composite during solidification to reduce
porosity and particle clusters. Microstructure examinations of the squeeze cast composites showed remarkable grain refining
compared with that of the matrix alloy. As the volume fraction of particles and applied squeeze pressure increased, the hardness
linearly increased. This increase was related to the modified structure and the decrease in the porosity. The effect of particle
volume fraction and squeeze pressure on the dry-sliding wear of the composites was studied. Experiments were performed at
10, 30, and 50 N with a sliding speed of 1 m/s using a pin-on-ring apparatus. Increasing the particle volume fraction and
squeeze pressure improved the wear resistance of the composite compared with that of the monolithic alloy, because the Al2O3 particles acted as load-bearing constituents. Also, these results can be attributed to the fact that the application of squeeze
pressure during solidification led to a reduction in the porosity, and an increase in the solidification rate, leading to
a finer structure. Moreover, the application of squeeze pressure improved the interface strength between the matrix and Al2O3 particles by elimination of the porosity at the interface, thereby providing better mechanical locking. 相似文献