全文获取类型
收费全文 | 1409篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 26篇 |
化学工业 | 117篇 |
金属工艺 | 51篇 |
机械仪表 | 60篇 |
建筑科学 | 13篇 |
矿业工程 | 38篇 |
能源动力 | 2篇 |
轻工业 | 5篇 |
水利工程 | 19篇 |
石油天然气 | 53篇 |
无线电 | 68篇 |
一般工业技术 | 232篇 |
冶金工业 | 548篇 |
原子能技术 | 152篇 |
自动化技术 | 29篇 |
出版年
2021年 | 15篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 39篇 |
2012年 | 34篇 |
2011年 | 21篇 |
2010年 | 29篇 |
2009年 | 20篇 |
2008年 | 31篇 |
2007年 | 35篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 121篇 |
1997年 | 79篇 |
1996年 | 62篇 |
1995年 | 40篇 |
1994年 | 34篇 |
1993年 | 44篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 20篇 |
1989年 | 24篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 22篇 |
1985年 | 17篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 22篇 |
1978年 | 19篇 |
1977年 | 32篇 |
1976年 | 68篇 |
1975年 | 20篇 |
1974年 | 14篇 |
1973年 | 17篇 |
1972年 | 14篇 |
1970年 | 16篇 |
1968年 | 14篇 |
1966年 | 12篇 |
排序方式: 共有1413条查询结果,搜索用时 234 毫秒
1.
O. Yu. Alekseev V. S. Borisov M. V. Davidovich N. F. Popova 《Journal of Communications Technology and Electronics》2006,51(11):1240-1247
Direct and inverse problems are considered for diffraction by an open end of a rectangular waveguide (RW) with a flange that adjoins a piecewise inhomogeneous planar layered lossy medium. Also considered are similar diffraction problems for a junction of an RW and a rectangular resonator filled with a multilayer medium and a junction of two RWs, one of which contains a multilayer plate. Such open and shielded waveguide probe structures (WPSs) are used for determination and nondestructive testing of parameters of multilayer samples. The direct problem is formulated on the basis of admittance and impedance algorithms with consideration for losses existing in the medium, flange, and screens. In this case, the approximation of the given aperture field allows obtainment of explicit solutions for open and shielded WPSs in the form of integrals. Solution of the inverse problem that lies in determining thicknesses, permittivities, and permeabilities of the layers from measured values of the magnitude of the reflection coefficient is obtained by minimizing the corresponding least-squares error and by constructing artificial neural networks. In order to increase the accuracy, it is proposed to use a two-port of errors and perform measurements for several positions of the sample with respect to the flange and different impedance conditions behind the sample. 相似文献
2.
3.
4.
N. Mitchell A. Alekseev R. Gallix D. Holland R. Meyder A. Panin M. Shimada F. Wong E. Zapretelina 《Journal of Fusion Energy》1997,16(1-2):25-35
The ITER magnet system consists of structurally linked sets of toroidal (TF) and poloidal (PF) field coils, central solenoid (CS), and various support structures. The coils are superconducting, force flow Helium cooled with a Kapton-Glass-Epoxy multilayer insulation system. The stored magnetic energy is about 100GJ in the TF system and 20GJ in the PF-CS. Coils and structure are maintained at 4 K by enclosing them in a vacuum cryostat. The cryostat, comprising an outer envelope to the magnets, forms most of the second radioactivity confinement barrier. The inner primary barrier is formed by the vacuum vessel, its ports and their extensions. To keep the machine size within acceptable bounds, it is essential that the magnets are in close proximity to both of the nuclear confinement barriers. The objective of the magnet design is that, although local damage to one of the barriers may occur in very exceptional circumstances, large scale magnet structural or thermal failure leading to simultaneous breaching of both barriers is not credible. Magnet accidents fall into three categories: thermal (which includes arcing arising from insulation failure and local overheating due to discharge failure in the event of a superconductor quench), structural (which includes component mechanical failure arising from material inadequacies, design errors and exceptional force patterns arising from coil shorts or control failures), and fluid (Helium release due to cooling line failure). After a preliminary survey to select initial faults conceivable within the present design, these faults are systematically analyzed to provide an assessment of the damage potential. The results of this damage assessment together with an assessment of the reliability of the monitoring and protective systems, shows that the magnets can operate with the required safety condition. 相似文献
5.
M Hessing D Kanters H Takeya C van 't Veer TM Hackeng S Iwanaga BN Bouma 《Canadian Metallurgical Quarterly》1993,317(3):228-232
Human C4b-binding protein (C4BP) functions as a cofactor to factor I in the degradation of C4b and accelerates the decay rate of the C4b2a complex. In this study we describe a monoclonal antibody directed against the alpha-chain of C4BP that inhibits the binding of C4b to C4BP. In order to identify the structural domain of the alpha-chain of C4BP that interacts with C4b, tryptic fragments of C4BP were generated. Amino acid sequence analysis of the fragments revealed that the residues Ser333-Arg356 of the alpha-chain of C4BP contain the epitope of this antibody, and as a consequence, that this part of the alpha-chain of C4BP is likely to be involved in the interaction with C4b. 相似文献
6.
7.
8.
BN Mehrotra 《Canadian Metallurgical Quarterly》1996,51(1-3):161-165
Forests are the chief resource for the collection and exploration of biological materials. The past few decades have witnessed a large scale deforestation in India due to substantial pressures generated by population growth, leading to demand for more land for agriculture, urbanization and industrial activities, in addition to increased demand for fuel wood and timber. This has resulted in the loss of soil cover, habitat destruction, environmental degradation and ecological imbalance. This scenario has created a progressive awareness for the conservation and restoration of habitats and, thus, the declaration of many forest areas into protected zones, such as national parks, biosphere reserves, etc., including the protection of some marine areas, by both the National and State Governments. Normally, permission for biological collecting is not granted in these protected areas. In India, forests are a State subject and grant for collection permission is vested with the State Forest Departments. In the absence of any rules, regulations and guidelines, either from National or State Governments, forest authorities impose their terms and conditions, which are arbitrary and even contradictory at times, in the process of granting collecting permits. A set of new rules to be applied throughout the country is needed. 相似文献
9.
10.