全文获取类型
收费全文 | 2540篇 |
免费 | 115篇 |
国内免费 | 9篇 |
学科分类
工业技术 | 2664篇 |
出版年
2024年 | 3篇 |
2023年 | 47篇 |
2022年 | 57篇 |
2021年 | 112篇 |
2020年 | 79篇 |
2019年 | 99篇 |
2018年 | 121篇 |
2017年 | 107篇 |
2016年 | 107篇 |
2015年 | 57篇 |
2014年 | 110篇 |
2013年 | 244篇 |
2012年 | 125篇 |
2011年 | 171篇 |
2010年 | 104篇 |
2009年 | 120篇 |
2008年 | 123篇 |
2007年 | 73篇 |
2006年 | 63篇 |
2005年 | 54篇 |
2004年 | 46篇 |
2003年 | 46篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 37篇 |
1999年 | 31篇 |
1998年 | 49篇 |
1997年 | 38篇 |
1996年 | 33篇 |
1995年 | 31篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 26篇 |
1991年 | 19篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1988年 | 23篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有2664条查询结果,搜索用时 15 毫秒
11.
12.
13.
Y Numagami AB Zubrow OP Mishra M Delivoria-Papadopoulos 《Canadian Metallurgical Quarterly》1997,69(4):1542-1547
Nitric oxide (NO) is reported to cause neuronal damage through various mechanisms. The present study tests the hypothesis that NO synthase inhibition by N(omega)-nitro-L-arginine (NNLA) will result in decreased oxygen-derived free radical production leading to the preservation of cell membrane structure and function during cerebral hypoxia. Ten newborn piglets were pretreated with NNLA (40 mg/kg); five were subjected to hypoxia, whereas the other five were maintained with normoxia. An additional 10 piglets without NNLA treatment underwent the same conditions. Hypoxia was induced with a lowered FiO2 and documented biochemically by decreased cerebral ATP and phosphocreatine levels. Free radicals were detected by using electron spin resonance spectroscopy with a spin trapping technique. Results demonstrated that free radicals, corresponding to alkoxyl radicals, were induced by hypoxia but were inhibited by pretreatment with NNLA before inducing hypoxia. NNLA also inhibited hypoxia-induced generation of conjugated dienes, products of lipid peroxidation. Na+,K+-ATPase activity, an index of cellular membrane function, decreased following hypoxia but was preserved by pretreatment with NNLA. These data demonstrate that during hypoxia NO generates free radicals via peroxynitrite production, presumably causing lipid peroxidation and membrane dysfunction. These results suggest that NO is a potentially limiting factor in the peroxynitrite-mediated lipid peroxidation resulting in membrane injury. 相似文献
14.
15.
Xingqun Jiang Mishra N. Turner J.N. Spencer M.G. 《Nanotechnology, IEEE Transactions on》2007,6(3):328-333
A novel method has been developed for fabricating full or partial freestanding anodic alumina. In our method a sacrificial metal layer is introduced between an Al film and a Si3N4 substrate. A freestanding alumina film at wafer scale is successfully achieved by anodizing the double metal layer, during which the alumina is spontaneously stripped off the Si3N4 substrate due to the anodic oxidation of the sacrificial layer. The barrier oxide of the alumina film is effectively removed either by H3PO4 dissolution or by CF4 reactive ion etching. The freestanding alumina film is utilized as a contact mask to transfer its nanoporous pattern to a Si substrate. By patterning the sacrificial metal layer with contact lithography, a partial freestanding alumina film is successfully achieved on the silicon chip, producing a unique micro/nanofluidic channel. Compared with previous techniques, the method reported here is advantageous for its simplicity and flexibility 相似文献
16.
AlGaN/GaN HEMTs-an overview of device operation and applications 总被引:5,自引:0,他引:5
Mishra U.K. Parikh P. Yi-Feng Wu 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2002,90(6):1022-1031
Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high-electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems. 相似文献
17.
Sushama Mishra B K Mishra D K Chokappa D O Shah C Manohar 《Bulletin of Materials Science》1994,17(6):1103-1108
It is conjectured that anionic-cationic surfactant combination can be regarded as equivalent to a double chain surfactant
and using molecular packing considerations it is shown that vesicles, viscoelastic solutions and liquid crystals can be designed
by the proper choice of chain lengths of the pair. Using these concepts new systems are designed, from mixtures of cetyltrimethyl
ammonium bromide and sodium alkyl sulfonates, to produce both viscoelastic gels and vesicles. 相似文献
18.
Fault-based side channel cryptanalysis is very effective against symmetric and asymmetric encryption algorithms. Although straightforward hardware and time redundancy based concurrent error detection (CED) architectures can be used to thwart such attacks, they entail significant overhead (either area or performance). In this paper we investigate two systematic approaches to low-cost, low-latency CED for symmetric encryption algorithm RC6. The proposed techniques have been validated on FPGA implementations of RC6, one of the advanced encryption standard finalists. 相似文献
19.
The temperature dependence of the viscosity of the undercooled melts exhibits an important role in the study of nucleation,
crystal growth and the glass-forming ability of materials. Several attempts have been made to study the viscous behaviour
of the glass-forming melts and these investigations are mainly based on free volume theory as well as on the configurational
entropy model. In the present investigation, an attempt has been made to correlate the thermodynamic parameters with the viscosity
of the glass-forming melts and to study the temperature dependence of the viscosity of undercooled liquids on the basis of
the free volume theory as well as on the basis of the configurational entropy model of Adam and Gibbs. The entire study is
confined on the expression for thermodynamic parameters reported by the authors recently. The expression obtained has been
successfully applied to study the temperature dependence of the viscosity of the metallic, molecular and oxide glass-forming
liquids. 相似文献
20.
Mishra S.K. Raghavan V.V. Tzeng N.-F. 《IEEE transactions on pattern analysis and machine intelligence》1991,17(7):731-734
Efficient solutions to the problem of optimally selecting recovery points are developed. The solutions are intended for models of computation in which task precedence has a tree structure and a task may fail due to the presence of faults. An algorithm to minimize the expected computation time of the task system under a uniprocessor environment has been developed for the binary tree model. The algorithm has time complexity of O (N 2), where N is the number of tasks, while previously reported procedures have exponential time requirements. The results are generalized for an arbitrary tree model 相似文献