全文获取类型
收费全文 | 272076篇 |
免费 | 4006篇 |
国内免费 | 891篇 |
专业分类
电工技术 | 5678篇 |
综合类 | 416篇 |
化学工业 | 37862篇 |
金属工艺 | 11202篇 |
机械仪表 | 9631篇 |
建筑科学 | 6191篇 |
矿业工程 | 1324篇 |
能源动力 | 6469篇 |
轻工业 | 23105篇 |
水利工程 | 2870篇 |
石油天然气 | 4610篇 |
武器工业 | 79篇 |
无线电 | 36069篇 |
一般工业技术 | 53421篇 |
冶金工业 | 48039篇 |
原子能技术 | 5715篇 |
自动化技术 | 24292篇 |
出版年
2021年 | 2511篇 |
2020年 | 1894篇 |
2019年 | 2466篇 |
2018年 | 4359篇 |
2017年 | 4453篇 |
2016年 | 4792篇 |
2015年 | 2975篇 |
2014年 | 4978篇 |
2013年 | 12509篇 |
2012年 | 7625篇 |
2011年 | 9889篇 |
2010年 | 7965篇 |
2009年 | 8966篇 |
2008年 | 9672篇 |
2007年 | 9615篇 |
2006年 | 8549篇 |
2005年 | 7588篇 |
2004年 | 7126篇 |
2003年 | 6765篇 |
2002年 | 6192篇 |
2001年 | 6214篇 |
2000年 | 6075篇 |
1999年 | 6139篇 |
1998年 | 14211篇 |
1997年 | 10269篇 |
1996年 | 7842篇 |
1995年 | 6369篇 |
1994年 | 5673篇 |
1993年 | 5541篇 |
1992年 | 4507篇 |
1991年 | 4164篇 |
1990年 | 4039篇 |
1989年 | 3742篇 |
1988年 | 3587篇 |
1987年 | 3136篇 |
1986年 | 3035篇 |
1985年 | 3580篇 |
1984年 | 3355篇 |
1983年 | 2991篇 |
1982年 | 2817篇 |
1981年 | 2914篇 |
1980年 | 2744篇 |
1979年 | 2635篇 |
1978年 | 2494篇 |
1977年 | 2919篇 |
1976年 | 3533篇 |
1975年 | 2305篇 |
1974年 | 2306篇 |
1973年 | 2294篇 |
1972年 | 1847篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Protection of Metals and Physical Chemistry of Surfaces - The present review is devoted to the sorption properties of magnetite towards hexavalent chromium ions and the possibility of its use as a... 相似文献
3.
4.
Avdeev Ya. G. Kuznetsov D. S. Kuznetsov Yu. I. 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(7):1307-1312
Protection of Metals and Physical Chemistry of Surfaces - Impedance spectroscopy was used to study the adsorption of the IFKhAN-92 inhibitor, a triazole derivative, on cathodically polarized... 相似文献
5.
Mechanical properties and thermal shock in thin ZrO2–Y2O3–Al2O3 films obtained by the sol-gel method
Antonio Díaz-Parralejo M. Ángeles Díaz-Díez José Sánchez-González Antonio Macías-García Juan Pablo Carrasco-Amador 《Ceramics International》2021,47(1):80-86
Thin multilayer coatings of ZrO2–Y2O3–Al2O3 were prepared using the sol-gel method and dip-coating technique in order to advance in the study of what influence the incorporation of Al2O3 has on films of Y2O3-doped ZrO2, investigating its role in the synthesis of the solutions and in the characteristics and properties of the coatings. After the characterization of the solutions used in the process, the microstructure of the films was studied and their mechanical behaviour and resistance to thermal shock were determined so as to optimize the characteristics and functionality of these coatings. With increased alumina content, 3YSZ-Al2O3 (20 mol%), the cubic phase of the zirconia disappeared completely at the sintering temperature used (700 °C), resulting in the tetragonal phase with Al in solution. There was also a decrease in the coatings' hardness and Young's modulus, and an increase in toughness and resistance to thermal shock. These results allow guidelines to be established for the design of multilayer structures that are, tougher, more resistant, and have improved surface properties. 相似文献
6.
Reliable joints of Ti3SiC2 ceramic and TC11 alloy were diffusion bonded with a 50 μm thick Cu interlayer. The typical interfacial structure of the diffusion boned joint, which was dependent on the interdiffusion and chemical reactions between Al, Si and Ti atoms from the base materials and Cu interlayer, was TC11/α-Ti + β-Ti + Ti2Cu + TiCu/Ti5Si4 + TiSiCu/Cu(s, s)/Ti3SiC2. The influence of bonding temperature and time on the interfacial structure and mechanical properties of Ti3SiC2/Cu/TC11 joint was analyzed. With the increase of bonding temperature and time, the joint shear strength was gradually increased due to enhanced atomic diffusion. However, the thickness of Ti5Si4 and TiSiCu layers with high microhardness increased for a long holding time, resulting in the reduction of bonding strength. The maximum shear strength of 251 ± 6 MPa was obtained for the joint diffusion bonded at 850 °C for 60 min, and fracture primarily occurred at the diffusion layer adjacent to the Ti3SiC2 substrate. This work provided an economical and convenient solution for broadening the engineering application of Ti3SiC2 ceramic. 相似文献
7.
Margarita A. Sazonova Vasily V. Sinyov Anastasia I. Ryzhkova Marina D. Sazonova Tatiana V. Kirichenko Victoria A. Khotina Zukhra B. Khasanova Natalya A. Doroschuk Vasily P. Karagodin Alexander N. Orekhov Igor A. Sobenin 《International journal of molecular sciences》2021,22(2)
Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism’s nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress. 相似文献
8.
Rasool Shumaila Cárdenas Pablo D. Pattison David I. Jensen Birgit Meyling Nicolai V. 《Journal of chemical ecology》2021,47(4-5):476-488
Journal of Chemical Ecology - Entomopathogenic fungi (EPF) can be experimentally established in several plant species as endophytes. Ecological effects of EPF inoculations on plant growth and... 相似文献
9.
Francesca Beretti Francesca Farnetani Luca Reggiani Bonetti Luca Fabbiani Manuela Zavatti Antonino Maiorana Giovanni Pellacani Tullia Maraldi 《International journal of molecular sciences》2021,22(2)
Background: Melanoma is the leading cause of death due to cutaneous malignancy and its incidence is on the rise. Several signaling pathways, including receptor tyrosine kinases, have a role in the development and progression of melanocytic lesions and malignant melanoma. Among those, the hepatocyte growth factor (HGF)/c-met axis is emerging as a critical player because it can play a role in drug resistance. Indeed, 50% of melanoma patients present BRAF mutations, however, all responders develop resistance to the inhibitors typically within one year of treatment. Interestingly, BRAF inhibitors induce reactive oxygen species (ROS) in melanoma cells, therefore, the aim of this study was to investigate a possible interplay between HGF/c-met and ROS sources, such as NADPH oxidases (Nox). Methods: The expression of c-met and Nox were quantified in 60 patients with primary cutaneous melanoma. In vitro experiments on melanoma primary cells and the cell line were performed to dissect the underpinned molecular mechanism. Results: The outcome of interest was the correlation between the high positivity for both Nox4 and c-met and metastasis occurring at least 1 year later than melanoma diagnosis in BRAF mutated patients, in contrast to nonmutated. In vitro experiments demonstrated that the axis HGF/c-met/Nox4/ROS triggers the epithelial-mesenchymal transition. Conclusions: The observed correlation suggests an interplay between c-met and Nox4 in promoting the onset of metastasis. This study suggests that Nox4 inhibitors could be associated to the current therapy used to treat melanoma patients with BRAF mutations. 相似文献
10.
Bosyakova N. A. Pomortsev S. A. Gizatullin R. G. Klyosov Yu. L. Laptov S. V. Kashcheev I. D. Zemlyanoi K. G. 《Refractories and Industrial Ceramics》2021,62(4):381-383
Refractories and Industrial Ceramics - Technology for producing alumina-periclase-carbon refractories of the brands APUK-D and APU-D is developed and implemented. Use of complex antioxidant and... 相似文献