全文获取类型
收费全文 | 8301篇 |
免费 | 630篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 126篇 |
综合类 | 8篇 |
化学工业 | 2327篇 |
金属工艺 | 146篇 |
机械仪表 | 175篇 |
建筑科学 | 290篇 |
矿业工程 | 20篇 |
能源动力 | 311篇 |
轻工业 | 1184篇 |
水利工程 | 77篇 |
石油天然气 | 21篇 |
无线电 | 577篇 |
一般工业技术 | 1490篇 |
冶金工业 | 836篇 |
原子能技术 | 51篇 |
自动化技术 | 1301篇 |
出版年
2024年 | 18篇 |
2023年 | 111篇 |
2022年 | 298篇 |
2021年 | 540篇 |
2020年 | 287篇 |
2019年 | 291篇 |
2018年 | 344篇 |
2017年 | 320篇 |
2016年 | 405篇 |
2015年 | 281篇 |
2014年 | 381篇 |
2013年 | 595篇 |
2012年 | 529篇 |
2011年 | 649篇 |
2010年 | 450篇 |
2009年 | 408篇 |
2008年 | 450篇 |
2007年 | 361篇 |
2006年 | 262篇 |
2005年 | 211篇 |
2004年 | 192篇 |
2003年 | 189篇 |
2002年 | 137篇 |
2001年 | 102篇 |
2000年 | 87篇 |
1999年 | 89篇 |
1998年 | 168篇 |
1997年 | 149篇 |
1996年 | 109篇 |
1995年 | 65篇 |
1994年 | 57篇 |
1993年 | 60篇 |
1992年 | 38篇 |
1991年 | 32篇 |
1990年 | 20篇 |
1989年 | 31篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 19篇 |
1984年 | 22篇 |
1983年 | 26篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 16篇 |
1973年 | 3篇 |
排序方式: 共有8940条查询结果,搜索用时 156 毫秒
11.
The rapid development of the science and technology of organic semiconductors has already led to mass application of organic light‐emitting diodes (OLEDs) in television monitors of outstanding quality as well as in a large variety of smaller displays found in smartphones, tablets, and other gadgets, while introduction of the technology to the illumination sector is imminent. Notably, the requirements of all such applications for emission in the visible range of the electromagnetic spectrum are well tuned to the optical and electronic properties of typical organic semiconductors, thereby representing relatively “low‐hanging fruits,” in terms of material development and exploitation. However, the question arises as to whether developing materials suited for efficient near‐infrared (NIR, 700–1000 nm) emission is possible, and, crucially, desirable to enable new classes of applications spanning from through‐space, short‐range communications to biomedical sensors, night vision, and more generally security applications to name but a few. Here, the major fundamental hurdles to be overcome to achieve efficient NIR emission from organic π‐conjugated systems are discussed, recent progress is reviewed, and an outlook for further development of both materials and applications is provided. 相似文献
12.
Silvia Ravera Esteban Colombo Claudio Pasquale Stefano Benedicenti Luca Solimei Antonio Signore Andrea Amaroli 《International journal of molecular sciences》2021,22(9)
Background: Injury of the trigeminal nerve in oral and maxillofacial surgery can occur. Schwann cell mitochondria are regulators in the development, maintenance and regeneration of peripheral nerve axons. Evidence shows that after the nerve injury, mitochondrial bioenergetic dysfunction occurs and is associated with pain, neuropathy and nerve regeneration deficit. A challenge for research is to individuate new therapies able to normalise mitochondrial and energetic metabolism to aid nerve recovery after damage. Photobiomodulation therapy can be an interesting candidate, because it is a technique involving cell manipulation through the photonic energy of a non-ionising light source (visible and NIR light), which produces a nonthermal therapeutic effect on the stressed tissue. Methods: The review was based on the following questions: (1) Can photo-biomodulation by red and NIR light affect mitochondrial bioenergetics? (2) Can photobiomodulation support damage to the trigeminal nerve branches? (preclinical and clinical studies), and, if yes, (3) What is the best photobiomodulatory therapy for the recovery of the trigeminal nerve branches? The papers were searched using the PubMed, Scopus and Cochrane databases. This review followed the ARRIVE-2.0, PRISMA and Cochrane RoB-2 guidelines. Results and conclusions: The reliability of photobiomodulatory event strongly bases on biological and physical-chemical evidence. Its principal player is the mitochondrion, whether its cytochromes are directly involved as a photoacceptor or indirectly through a vibrational and energetic variation of bound water: water as the photoacceptor. The 808-nm and 100 J/cm2 (0.07 W; 2.5 W/cm2; pulsed 50 Hz; 27 J per point; 80 s) on rats and 800-nm and 0.2 W/cm2 (0.2 W; 12 J/cm2; 12 J per point; 60 s, CW) on humans resulted as trustworthy therapies, which could be supported by extensive studies. 相似文献
13.
14.
Andrea Mariela Araya-Sibaja Valdir Soldi Carlos Eduardo Maduro Campos Simone Gonçalves Cardoso 《Drug development and industrial pharmacy》2015,41(5):851-858
Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications. 相似文献
15.
16.
17.
18.
Francesco Di Girolamo Andrea Masotti Isabella Lante Margherita Scapaticci Cosima Damiana Calvano Carlo Zambonin Maurizio Muraca Lorenza Putignani 《International journal of molecular sciences》2015,16(9):20896-20912
Extra virgin olive oil (EVOO) with its nutraceutical characteristics substantially contributes as a major nutrient to the health benefit of the Mediterranean diet. Unfortunately, the adulteration of EVOO with less expensive oils (e.g., peanut and corn oils), has become one of the biggest source of agricultural fraud in the European Union, with important health implications for consumers, mainly due to the introduction of seed oil-derived allergens causing, especially in children, severe food allergy phenomena. In this regard, revealing adulterations of EVOO is of fundamental importance for health care and prevention reasons, especially in children. To this aim, effective analytical methods to assess EVOO purity are necessary. Here, we propose a simple, rapid, robust and very sensitive method for non-specialized mass spectrometric laboratory, based on the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) coupled to unsupervised hierarchical clustering (UHC), principal component (PCA) and Pearson’s correlation analyses, to reveal corn oil (CO) adulterations in EVOO at very low levels (down to 0.5%). 相似文献
19.
20.
Andrea Bedon Jean Paul Viricelle Mathilde Rieu Simone Mascotto Antonella Glisenti 《International Journal of Hydrogen Energy》2021,46(27):14735-14747
In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca2FeAl0.95Mg0.05O5) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeOx/CGO/CFA + FeOx) and complete cells (CFA + FeOx/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeOx is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated. 相似文献