全文获取类型
收费全文 | 4862篇 |
免费 | 264篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 32篇 |
综合类 | 5篇 |
化学工业 | 1018篇 |
金属工艺 | 96篇 |
机械仪表 | 102篇 |
建筑科学 | 240篇 |
矿业工程 | 8篇 |
能源动力 | 152篇 |
轻工业 | 471篇 |
水利工程 | 48篇 |
石油天然气 | 18篇 |
武器工业 | 2篇 |
无线电 | 429篇 |
一般工业技术 | 904篇 |
冶金工业 | 845篇 |
原子能技术 | 29篇 |
自动化技术 | 738篇 |
出版年
2024年 | 6篇 |
2023年 | 43篇 |
2022年 | 82篇 |
2021年 | 136篇 |
2020年 | 96篇 |
2019年 | 110篇 |
2018年 | 143篇 |
2017年 | 126篇 |
2016年 | 159篇 |
2015年 | 118篇 |
2014年 | 158篇 |
2013年 | 277篇 |
2012年 | 274篇 |
2011年 | 338篇 |
2010年 | 241篇 |
2009年 | 265篇 |
2008年 | 301篇 |
2007年 | 284篇 |
2006年 | 232篇 |
2005年 | 243篇 |
2004年 | 173篇 |
2003年 | 149篇 |
2002年 | 158篇 |
2001年 | 76篇 |
2000年 | 68篇 |
1999年 | 60篇 |
1998年 | 70篇 |
1997年 | 66篇 |
1996年 | 71篇 |
1995年 | 53篇 |
1994年 | 52篇 |
1993年 | 54篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 38篇 |
1989年 | 38篇 |
1988年 | 31篇 |
1987年 | 42篇 |
1986年 | 39篇 |
1985年 | 33篇 |
1984年 | 26篇 |
1983年 | 29篇 |
1982年 | 27篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1974年 | 5篇 |
排序方式: 共有5137条查询结果,搜索用时 0 毫秒
141.
Holmes Josie Groce Alex Pinto Jervis Mittal Pranjal Azimi Pooria Kellar Kevin O’Brien James 《International Journal on Software Tools for Technology Transfer (STTT)》2018,20(1):57-78
International Journal on Software Tools for Technology Transfer - A test harness, in automated test generation, defines the set of valid tests for a system, as well as their correctness properties.... 相似文献
142.
Adam S. Hollinger Dylan R. McAnallen Matthew T. Brockett Scott C. DeLaney Jun Ma Christopher D. Rahn 《国际能源研究杂志》2020,44(1):560-566
The low cost, simplicity, and easy use of battery-powered multirotor aircraft has led to their adoption in commercial, industrial, agricultural, and military applications. These aircraft, however, have limited payloads and shorter endurance and range than fuel-powered conventional aircraft. To extend these key performance metrics, a structural battery is developed that uses commercially available battery cells as load bearing and power source elements for weight critical applications. The cylindrical structural battery is tested in three-point bending and is found to have four times higher stiffness and two times higher yield strength than the structure without battery reinforcement. Simulations of a quadcopter, redesigned with the proposed cylindrical structural batteries, demonstrate 41% longer hover time. 相似文献
143.
144.
Kevin Heritage Ben Bryant Laura A. Fenner Andrew S. Wills Gabriel Aeppli Yeong‐Ah Soh 《Advanced functional materials》2020,30(36)
First‐order phase transitions, where one phase replaces another by virtue of a simple crossing of free energies, are best known between solids, liquids, and vapors, but they also occur in a wide range of other contexts, including even elemental magnets. The key challenges are to establish whether a phase transition is indeed first order, and then to determine how the new phase emerges because this will determine thermodynamic and electronic properties. Here it is shown that both challenges are met for the spin reorientation transition in the topological metallic ferromagnet Fe3Sn2. The magnetometry and variable temperature magnetic force microscopy experiments reveal that, analogous to the liquid–gas transition in the temperature–pressure plane, this transition is centered on a first‐order line terminating in a critical end point in the field‐temperature plane. The nucleation and growth associated with the transition is directly imaged, indicating that the new phase emerges at the most convoluted magnetic domain walls for the high temperature phase and then moves to self‐organize at the domain centers of the high temperature phase. The dense domain patterns and phase coexistence imply a complex inhomogenous electronic structure, which can yield anomalous contributions to the electrical conductivity. 相似文献
145.
Camden Debruler Wenda Wu Kevin Cox Brice Vanness T. Leo Liu 《Advanced functional materials》2020,30(24)
Here, a pH neutral aqueous organic redox flow battery (AORFB) consisting of three electrolytes channels (i.e., an anolyte channel, a catholyte channel, and a central salt water channel) to achieve integrated energy storage and desalination is reported. Employing a low cost, chemically stable methyl viologen (MV) anolyte, and sodium ferrocyanide catholyte, this desalination AORFB is capable of desalinating simulated seawater (0.56 m NaCl) down to 0.023 m salt concentration at an energy cost of 2.4 W h L?1 of fresh water—competitive with current reverse osmosis technologies. Simultaneously, the cell delivers stored energy at 79.7% efficiency with a cell voltage of 0.85 V. Furthermore, the cell is also capable of higher current operation up to 15 mA cm?2, providing 4.55 mL of fresh water per hour. Combining energy storage and water desalination into such a bifunctional device offers the opportunity to address two growing global issues from one hardware installation. 相似文献
146.
147.
148.
M. Vahl Kevin J?rgensen 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,206(4):243-245
A liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometric method is described for the determination
of aflatoxins B1, B2, G1 and G2 in food with the use of aflatoxin M1 as an internal standard. The method works well with matrices such as those of figs and peanuts, but there are problems with
spices, due to limitations of the clean-up method used.
Received: 15 October 1997 相似文献
149.
Keliang Gao Lei Li Lingna He Kevin Hinkle Yun Wu Junyu Ma Lingqian Chang Xi Zhao Daniel Gallego Perez Sigrid Eckardt John Mclaughlin Boyu Liu Dave F. Farson L. James Lee 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(5):1015-1023
A micro/nano‐fabrication process of a nanochannel electroporation (NEP) array and its application for precise delivery of plasmid for non‐viral gene transfection is described. A dip‐combing device is optimized to produce DNA nanowires across a microridge array patterned on the polydimethylsiloxane (PDMS) surface with a yield up to 95%. Molecular imprinting based on a low viscosity resin, 1,4‐butanediol diacrylate (1,4‐BDDA), adopted to convert the microridge‐nanowire‐microridge array into a microchannel‐nanochannel‐microchannel (MNM) array. Secondary machining by femtosecond laser ablation is applied to shorten one side of microchannels from 3000 to 50 μm to facilitate cell loading and unloading. The biochip is then sealed in a packaging case with reservoirs and microfluidic channels to enable cell and plasmid loading, and to protect the biochip from leakage and contamination. The package case can be opened for cell unloading after NEP to allow for the follow‐up cell culture and analysis. These NEP cases can be placed in a spinning disc and up to ten discs can be piled together for spinning. The resulting centrifugal force can simultaneously manipulate hundreds or thousands of cells into microchannels of NEP arrays within 3 minutes. To demonstrate its application, a 13 kbp OSKM plasmid of induced pluripotent stem cell (iPSC) is injected into mouse embryonic fibroblasts cells (MEFCs). Fluorescence detection of transfected cells within the NEP biochips shows that the delivered dosage is high and much more uniform compared with similar gene transfection carried out by the conventional bulk electroporation (BEP) method. 相似文献
150.
Aptamer-based electrochemical detection of picomolar platelet-derived growth factor directly in blood serum 总被引:2,自引:0,他引:2
We report an electrochemical, aptamer-based (E-AB) sensor for the detection of platelet-derived growth factor (PDGF) directly in blood serum. The E-AB approach employs alternating current voltammetry to monitor target-induced folding in a methylene blue-modified, PDGF-binding aptamer. The sensor is sensitive, highly selective, and essentially reagentless: we readily detect the BB variant of PDGF at 1 nM directly in undiluted, unmodified blood serum and at 50 pM (1.25 ng/mL) in serum-diluted 2-fold with aqueous buffer. The sensitivity and selectivity achieved by this sensor match or significantly exceed those of the best analogous optical approaches. For example, the detection limit attained in 50% serum is achieved against a >25 million-fold excess of contaminating blood proteins and represents a 4 order of magnitude improvement over the most sensitive optical PDGF aptasensor reported to date. Moreover, the E-AB sensor combines these promising attributes in a platform that is reusable, label-free, and electronic. Given these advantages, E-AB sensors appear well suited for implementation in portable microdevices directed at the direct detection of proteins and small molecules in complex, largely unprocessed clinical samples. 相似文献