全文获取类型
收费全文 | 1780篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 27篇 |
金属工艺 | 26篇 |
机械仪表 | 38篇 |
建筑科学 | 2篇 |
矿业工程 | 10篇 |
能源动力 | 1篇 |
轻工业 | 11篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
无线电 | 11篇 |
一般工业技术 | 51篇 |
冶金工业 | 1537篇 |
原子能技术 | 39篇 |
自动化技术 | 27篇 |
出版年
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2017年 | 14篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 34篇 |
1998年 | 449篇 |
1997年 | 261篇 |
1996年 | 183篇 |
1995年 | 144篇 |
1994年 | 87篇 |
1993年 | 84篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 17篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 25篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 57篇 |
1976年 | 104篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1970年 | 3篇 |
1966年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有1789条查询结果,搜索用时 15 毫秒
1.
We characterize the meander of re-entrant excitation in a model of a sheet of mammalian ventricular tissue, and its control by resonant drift under feedback driven stimulation. The Oxsoft equations for excitability in a guinea pig single ventricular cell were incorporated in a two dimensional reaction-diffusion system to model homogeneous, isotropic tissue with a plane wave conduction velocity of 0.35 m s-1. Re-entrant spiral wave solutions have a spatially extended transient motion (linear core) that settles down into rotation with an irregular period of 100-110 ms around an irregular, multi-lobed spiky core. In anisotropic tissue this would appear as a linear conduction block. The typical velocity of drift of the spiral wave induced by low amplitude resonant forcing is 0.4 cm s-1. 相似文献
2.
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
3.
SA Balakirev VI Tsygankin AV Ivanov VI Atroshchenko AN Ianovski? M Sarfundin 《Canadian Metallurgical Quarterly》1997,43(4):445-447
The report deals with the development of procedures, evaluation of laser application and prevention of complications involved in intensive chemoradiation therapy of neoplasms of hemopoietic and lymphoid tissue in childhood. The clinical data on 548 patients, aged 2 months-15 years, with leukemia and solid tumor were evaluated. Laser application for treatment of different complications of chemoradiation therapy of pediatric leukemia proved a valuable innovation. It had a pronounced antiinflammatory and analgetic effect, promoted tissue regeneration processes and cut down the duration of complication treatment drastically. 相似文献
4.
5.
Conclusion In the optimization problem [f
0(x)│hi(x)<-0,i=1,…,l] relaxation of the functionf
0(x)+Nh+(x) does not produce, as we know [6, 7], αk=1 in Newton's method with the auxiliary problem (5), (6), whereF(x)=f
0′(x). For this reason, Newton type methods based on relaxation off
0(x)+Nh+(x) are not superlinearly convergent (so-called Maratos effect). The results of this article indicate that if (F(x)=f
0′(x), then replacement of the initial optimization problem with a larger equivalent problem (7) eliminates the Maratos effect
in the proposed quasi-Newton method. This result is mainly of theoretical interest, because Newton type optimization methods
in the space of the variablesx ∈R
n are less complex. However to the best of our knowledge, the difficulties with nonlocal convergence arising in these methods
(choice of parameters, etc.) have not been fully resolved [10, 11]. The discussion of these difficulties and comparison with
the proposed method fall outside the scope of the present article, which focuses on solution of variational inequalities (1),
(2) for the general caseF′(x)≠F′
T(x).
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 78–91, November–December, 1994. 相似文献
6.
AV Pensler 《Canadian Metallurgical Quarterly》1998,19(4):387-90, 392-4, 396; quiz 398
7.
8.
9.
AV Stefano LF Canosa JL D'Eramo O Fridman JM Affanni GM Somoza 《Canadian Metallurgical Quarterly》1997,118(3):335-345
Gonadotropin-releasing hormone (GnRH) molecular variants in the brain and pituitary gland of pejerrey, Odontesthes bonariensis (Atheriniformes), were characterized by gradient reverse phase high performance liquid chromatography (RP-HPLC). Eluted fractions were tested in radioimmunoassays with different antisera. The results show that the brain extract contains three forms of GnRH: one is immunologically and chromatographically similar to cIIGnRH (chicken II), and another is similar to sGnRH (salmon). A third GnRH appears to be chromatographic and immunologically different from the nine other known forms of the vertebrate hormone. This is the only variant present in the pituitary gland. 相似文献
10.