全文获取类型
收费全文 | 411篇 |
免费 | 14篇 |
专业分类
电工技术 | 10篇 |
综合类 | 1篇 |
化学工业 | 76篇 |
金属工艺 | 6篇 |
机械仪表 | 7篇 |
建筑科学 | 12篇 |
能源动力 | 9篇 |
轻工业 | 17篇 |
无线电 | 73篇 |
一般工业技术 | 92篇 |
冶金工业 | 56篇 |
原子能技术 | 2篇 |
自动化技术 | 64篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 15篇 |
2021年 | 21篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 17篇 |
2012年 | 7篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 20篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1970年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有425条查询结果,搜索用时 15 毫秒
31.
Determining points-to sets is an important static-analysis problem. Most of the classic static analyses (used e.g., by compilers
or in programming environments) rely on knowing which variables might be used or defined by each expression in a program.
In the presence of pointers, the use/def set of an expression like *p = *q can only be determined given (safe) points-to sets for p and q.
Previous work has shown that both precise flow-sensitive and precise flow-insensitive pointer analysis is NP-Hard, even when
restricted to single-procedure programs with no dynamic memory allocation. In this paper, we show that it is not even possible
to compute good approximations to the precise solutions (i.e., to compute points-to sets whose sizes are within a constant
factor of the sizes of the precise points-to sets) unless P=NP.
Received: 1 November 2001 / 4 February 2002 相似文献
32.
33.
Hudgins J.L. Bailey D.W. Dougal R.A. Venkatesan V. 《Power Electronics, IEEE Transactions on》1995,10(5):615-620
The ionization process in a high gain photoconductive GaAs power switch is explored computationally, based on a streamer model. The streamer velocity was found to increase with increasing electric field, decreasing temperature, or increasing background ionization density. The electric field dependence of streamer velocity is consistent with experimental observations, lending support for the model's predictions about the temperature and background ionization density dependencies. The large electric field associated with the highly charged streamer tip allows virtual propagation of the ionization column at speeds above 10 8 cm/s, well in excess of the carrier saturated drift velocity 相似文献
34.
Five parallel transfer function formulations for digital filters are given. The coefficients in these allow a simple and very fast multiplication process. These functions provide a maximum bandwidth of about double that of an earlier set. 相似文献
35.
Venkatesan Guruswami 《Algorithmica》2003,38(3):451-469
We prove hardness results for approximating set splitting problems and
also instances of satisfiability problems which have no mixed
clauses, i.e., every clause has either all its literals unnegated or
all of them negated. Results of Håstad imply tight
hardness results for set splitting when all sets have size exactly $k
\ge 4$ elements and also for non-mixed satisfiability problems with
exactly $k$ literals in each clause for $k \ge 4$. We consider the
case $k=3$. For the MAX E3-SET SPLITTING, problem in which all sets have size
exactly 3, we prove an NP-hardness result for approximating within
any factor better than ${\frac{19}{20}}$. This result holds even for satisfiable
instances of MAX E3-SET SPLITTING, and is based on a PCP construction due to
Håstad. For non-mixed MAX 3SAT, we give a
PCP construction which is a slight variant of the one given by Håstad for MAX 3SAT, and use it to prove the NP-hardness of
approximating within a factor better than ${\frac{11}{12}}$. 相似文献
36.
Mittle V. N. Venkatesan K. Gupta S. C. 《Industry Applications, IEEE Transactions on》1980,(1):119-126
The stability analysis of a static slip-power-recovery drive is presented A set of nonlinear differential equation describing the dynamics of the system are developed and linearized about an operating point using perturbation technique. Using the characteristic equation obtained from the motional impedance matrix and the Routh-Hurwitz criterion instability regions have been plotted in the torque-firing angle plane. The effects of system inertia, filter parameters, and applied voltage upon the instability regions have been investigated. An experimental verification of the stability region has also been presented. 相似文献
37.
K.A. Venkatesan Dinesh K. Patre K.N. Sabharwal T.G. Srinivasan P.R. Vasudeva Rao 《溶剂提取与离子交换》2013,31(3):551-565
ABSTRACT The rate of extraction of uranium by macroporous bifunctional phosphinic acid (MPBPA) resin from nitric acid medium has been studied under particle diffusion controlled conditions. The internal diffusion coefficient was found to increase with increase in temperature and decrease with increase in particle size. The activation energies and entropies suggest that the extraction of uranium essentially follows ion exchange mechanism at low concentration of nitric acid while it is through linkage of >P=0 group of the resin at high concentrations. 相似文献
38.
Paulraj Kanmani Ramraj Satishkumar Neelakandan Yuvaraj Kupusamy Alagesan Paari Vellaiyan Pattukumar Venkatesan Arul 《Korean Journal of Chemical Engineering》2011,28(3):860-866
The aim of this study was to optimize medium composition for higher yield of total viable cells and bacteriocin by Enterococcus faecium MC13. The factors such as peptone, meat extract, yeast extract, lactose, glycerol, tween 80, triammonium citrate and K2HPO4 were selected based on the Lactobacillus MRS medium composition. Two level factorial designs (FD) and steepest ascent path were performed to identify vital factors among the variables. Through the 2?8 FD, peptone, yeast extract and lactose were found to be significant factors involved in the enhanced production of viable cells and bacteriocin. Therefore, these three foremost factors were further optimized by central composite design to achieve efficient yield. The optimum MRS composition was found to be peptone (40.0 g/L), meat extract (30.0 g/L), yeast extract (40.0 g/L), lactose (24.0 g/L), glycerol (5.8 g/L), Tween 80 (3.0 g/L), triammonium citrate (1.0 g/L), K2HPO4 (2.5 g/L), MgSO4·7H2O (0.10 g/L), MnSO4·7H2O (0.05 g/L) and dipotassium PO4 (2.0 g/L). The optimized growth medium allowed higher amount of bacteriocin activity (36,100 AUml?1) and total viable cells (14.22 LogCFUml?1) production which were two-times higher than the commercial MRS medium. 相似文献
39.
40.