全文获取类型
收费全文 | 283篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 101篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 22篇 |
轻工业 | 22篇 |
武器工业 | 1篇 |
无线电 | 29篇 |
一般工业技术 | 28篇 |
冶金工业 | 20篇 |
原子能技术 | 2篇 |
自动化技术 | 30篇 |
出版年
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 27篇 |
2012年 | 7篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 8篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1938年 | 1篇 |
1934年 | 2篇 |
排序方式: 共有290条查询结果,搜索用时 15 毫秒
41.
42.
Stuchly Maria A. Kraszewski Andrzej Stuchly Stanislaw S. Hartsgrove George W. Spigel Ronald J. 《IEEE transactions on bio-medical engineering》1987,(12):944-950
The electric field strength was measured in a full-scale heterogeneous model of man exposed in the near field of resonant dipoles. The model was comprised of skull, spinal cord, rib cage, all other major bones, brain, lung, and muscle tissue. Electrical properties of these simulated tissues were the same as respective live tissue properties at test frequencies of 160, 350, and 915 MHz. The rates of energy absorption were calculated on the basis of the measured field strengths and tissue conductivities. Patterns of the energy deposition are compared for two orientations of the antennas with respect to the body. Also the results for the heterogeneous model are compared to data for homogeneous model having average tissue electrical properties. 相似文献
43.
44.
This paper deals with the study of thermal stresses due to a plane crack lying on an interface in a microperiodic two-layered composite under a uniform perpendicular heat flow. An approximate analysis is carried out within the framework of linear stationary thermoelasticity with microlocal parameters. Taking this approach, a general method of solving the resulting boundary-value problem is presented. Effective results have been achieved through the use of suitable potential solutions and reducing the thermal crack problem to its skew-symmetric isothermal mechanical counterpart. An illustrative example is given in the paper by considering an insulated stress-free penny-shaped crack. For this problem the solution is obtained in terms of elementary functions and discussed from the point of view of fracture theory. 相似文献
45.
A Distributed Key Generation (DKG) protocol is an essential component of threshold cryptosystems required to initialize the
cryptosystem securely and generate its private and public keys. In the case of discrete-log-based (dlog-based) threshold signature
schemes (ElGamal and its derivatives), the DKG protocol is further used in the distributed signature generation phase to generate
one-time signature randomizers (r = gk). In this paper we show that a widely used dlog-based DKG protocol suggested by Pedersen does not guarantee a uniformly random
distribution of generated keys: we describe an efficient active attacker controlling a small number of parties which successfully
biases the values of the generated keys away from uniform. We then present a new DKG protocol for the setting of dlog-based
cryptosystems which we prove to satisfy the security requirements from DKG protocols and, in particular, it ensures a uniform
distribution of the generated keys. The new protocol can be used as a secure replacement for the many applications of Pedersen's
protocol. Motivated by the fact that the new DKG protocol incurs additional communication cost relative to Pedersen's original
protocol, we investigate whether the latter can be used in specific applications which require relaxed security properties
from the DKG protocol. We answer this question affirmatively by showing that Pedersen's protocol suffices for the secure implementation
of certain threshold cryptosystems whose security can be reduced to the hardness of the discrete logarithm problem. In particular,
we show Pedersen's DKG to be sufficient for the construction of a threshold Schnorr signature scheme. Finally, we observe
an interesting trade-off between security (reductions), computation, and communication that arises when comparing Pedersen's
DKG protocol with ours. 相似文献
46.
The technique of the realisation of nth-order transfer functions with only two operational amplifiers is presented. 相似文献
47.
M Radkowski M Sadowska E Kopicz-Kamińska A Horban J Slusarczyk 《Canadian Metallurgical Quarterly》1996,1(5):325-326
Results of quantitative determinations of peripheral blood lymphocytes presenting CD4 or simultaneously CD4 and CD8 antigens as well as HLA-DR and CD25 antigens in patients with different clinical stages of CD4+ and CD4+CD8+ cells were observed. The fall of CD4+CD8+ lymphocytes percentage was slight in the initial stages of infection but more sharp during the full-blown AIDS. The percentage of HLA-DR positive cells was higher in seropositive patients in comparison with controls and increased with the progression of HIV infection into AIDS. The CD25 expression was also higher in HIV-infected patients, however, it decreased in patients with late stages of AIDS. The observed disturbances could be caused by the direct destruction by replicating HIV or by severe abnormalities of immune system function. 相似文献
48.
49.
Jacek Chroscielewski Zbigniew Cywinski Ireneusz Kreja Stanislaw Uminski 《Computers & Structures》1983,17(1):37-44
Computer aided finite element analysis has been applied to evaluate the structural behavior of a solid plate representing statically certain box-type construction of a dry dock gate. Possible comparison of particular results following from different procedures, valid for constant plate stiffness and rigid supports, has been performed and the distribution of reactions for variable plate stiffness, within two different numerical accuracies, has been studied. For practical requirements the nonlinear elastic flexibility of dock gate packing has been taken into account and an adequate numerical step-by-step approach, satisfying the considered material characteristics, developed. For last case the deflections, reactions, and internal forces have been examined in detail and a comparison with those for rigid supports presented. 相似文献
50.
Andrzej Cichocki Stanislaw Osowski 《International journal for numerical methods in engineering》1977,11(5):900-904
A simple method for solving the matrix equation describing the general active ladder network, is presented. Using Coates flow graphs and continuants the expressions for current, voltage, and also example of application are given. 相似文献