全文获取类型
收费全文 | 3426篇 |
免费 | 10篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 210篇 |
金属工艺 | 10篇 |
机械仪表 | 27篇 |
建筑科学 | 45篇 |
矿业工程 | 3篇 |
能源动力 | 17篇 |
轻工业 | 221篇 |
水利工程 | 6篇 |
石油天然气 | 3篇 |
无线电 | 59篇 |
一般工业技术 | 163篇 |
冶金工业 | 2485篇 |
原子能技术 | 10篇 |
自动化技术 | 167篇 |
出版年
2024年 | 9篇 |
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 26篇 |
2018年 | 36篇 |
2017年 | 27篇 |
2016年 | 30篇 |
2015年 | 20篇 |
2014年 | 35篇 |
2013年 | 73篇 |
2012年 | 51篇 |
2011年 | 64篇 |
2010年 | 49篇 |
2009年 | 54篇 |
2008年 | 53篇 |
2007年 | 57篇 |
2006年 | 32篇 |
2005年 | 33篇 |
2004年 | 21篇 |
2003年 | 34篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 74篇 |
1998年 | 782篇 |
1997年 | 440篇 |
1996年 | 285篇 |
1995年 | 157篇 |
1994年 | 156篇 |
1993年 | 137篇 |
1992年 | 25篇 |
1991年 | 33篇 |
1990年 | 30篇 |
1989年 | 47篇 |
1988年 | 41篇 |
1987年 | 27篇 |
1986年 | 31篇 |
1985年 | 31篇 |
1984年 | 4篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 23篇 |
1980年 | 28篇 |
1978年 | 9篇 |
1977年 | 72篇 |
1976年 | 149篇 |
1975年 | 6篇 |
1968年 | 2篇 |
排序方式: 共有3436条查询结果,搜索用时 15 毫秒
91.
92.
The outdating of units of blood can be reduced by decreasing the amount of time they spend in an assigned or crossmatched status. This reduction can be achieved in a hospital by establishing a maximum surgical blood order schedule (MSBOS) which reduces the excessive number of units of blood crossmatched preoperatively for patients undergoing elective surgery. The various steps which occurred in the development of a MSBOS in a large general hospital are detailed and the projected reduction in the number of crossmatched units which can be achieved with the MSBOS is illustrated. illustrated. The projected number of units of blood transfused to patients during their hospitalization for 50 common primary surgical procedures in the United States during 1974 is presented as a basis for defining maximum blood orders for each procedure. 相似文献
93.
94.
Castillo E Fontenla-Romero O Guijarro-Berdiñas B Alonso-Betanzos A 《Neural computation》2002,14(6):1429-1449
The article presents a method for learning the weights in one-layer feedforward neural networks minimizing either the sum of squared errors or the maximum absolute error, measured in the input scale. This leads to the existence of a global optimum that can be easily obtained solving linear systems of equations or linear programming problems, using much less computational power than the one associated with the standard methods. Another version of the method allows computing a large set of estimates for the weights, providing robust, mean or median, estimates for them, and the associated standard errors, which give a good measure for the quality of the fit. Later, the standard one-layer neural network algorithms are improved by learning the neural functions instead of assuming them known. A set of examples of applications is used to illustrate the methods. Finally, a comparison with other high-performance learning algorithms shows that the proposed methods are at least 10 times faster than the fastest standard algorithm used in the comparison. 相似文献
95.
N6-(p-Azidobenzyl)adenosine (ABA) and nitrobenzylthioinosine (NBMPR) were employed as covalent probes of the nucleoside transport mechanism in human erythrocytes. NBMPR, a potent inhibitor of nucleoside transport, binds tightly (KD 0.3-1 nM) to specific sites on nucleoside transporter elements. ABA, a less potent inhibitor of uridine influx, competitively inhibited NBMPR binding (Ki 15 nM). [3H]ABA was bound tightly (KD 13.4 nM) but reversibly to sites on erythrocytes which appeared to be those which bind NBMPR. ABA binding was inhibited by uridine and adenosine. Irradiation with UV light caused site-bound [3H]ABA on erythrocyte membranes to become covalently bound and, similarly, photoactivation resulted in covalent attachment of membrane-bound [3H]NBMPR. In the presence of dithiothreitol, a free radical scavenger, photoactivation of the site-bound 3H-ligand on membranes depleted of extrinsic membrane proteins resulted in selective incorporation of 3H into band 4.5 of the membrane polypeptides which were resolved on sodium dodecyl sulfate-polyacrylamide gel electropherograms. This result, when considered with previous findings, indicates that the NBMPR-binding component of the nucleoside transport mechanism (or the entire mechanism, if the NBMPR site is an integral part) is a band 4.5 polypeptide. 相似文献
96.
A group of public health scientists from the United States and The Netherlands met at a Bicentennial Round Table Conference December 1-2, 1982, to discuss the latest developments in immunization against infectious diseases, focusing on pertussis, poliomyelitis, measles, and rubella. The major differences in immunization practices in the two countries are: (a) In The Netherlands, inactivated polio vaccine is used exclusively; in the United States, the oral polio vaccine is used. Polio-myelitis has virtually disappeared from both countries. (b) In The Netherlands, the pertussis component of DTP (diphtheria, tetanus, pertussis) is not given to children over the age of 1 year, whereas in the United States, it is given to children up to their seventh birthday. (c) Rubella vaccine is given only to girls at ages 11-12 years in The Netherlands, but to all children at ages 12-15 months in the United States. (d) Mumps vaccine is not administered to children in The Netherlands, but in the United States it is given routinely to children at 12-15 months (in combination with measles and rubella vaccine). The participants concluded that both the United States and The Netherlands have effective immunization programs that have significantly reduced the impact of these diseases. 相似文献
97.
J. L. J. Laredo P. A. Castillo A. M. Mora J. J. Merelo 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(12):1145-1156
In this work we propose a fine grained approach with self-adaptive migration rate for distributed evolutionary computation.
Our target is to gain some insights on the effects caused by communication when the algorithm scales. To this end, we consider
a set of basic topologies in order to avoid the overlapping of algorithmic effects between communication and topological structures.
We analyse the approach viability by comparing how solution quality and algorithm speed change when the number of processors
increases and compare it with an Island model based implementation. A finer-grained approach implies a better chance of achieving
a larger scalable system; such a feature is crucial concerning large-scale parallel architectures such as peer-to-peer systems.
In order to check scalability, we perform a threefold experimental evaluation of this model: first, we concentrate on the
algorithmic results when the problem scales up to eight nodes in comparison with how it does following the Island model. Second,
we analyse the computing time speedup of the approach while scaling. Finally, we analyse the network performance with the
proposed self-adaptive migration rate policy that depends on the link latency and bandwidth. With this experimental setup,
our approach shows better scalability than the Island model and a equivalent robustness on the average of the three test functions
under study. 相似文献
98.
P. García-Sánchez J. González P. A. Castillo M. G. Arenas J. J. Merelo-Guervós 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2013,17(6):1059-1075
This work presents a service oriented architecture for evolutionary algorithms, and an implementation of this architecture using a specific technology (called OSGiLiath). Service oriented architecture is a computational paradigm where users interact using services to increase the integration between systems. The presented abstract architecture is formed by loosely coupled, highly configurable and language-independent services. As an example of an implementation of this architecture, a complete process development using a specific service oriented technology is explained. With this implementation, less effort than classical development in integration, distribution mechanisms and execution time management has been attained. In addition, steps, ideas, advantages and disadvantages, and guidelines to create service oriented evolutionary algorithms are presented. Using existing software, or from scratch, researchers can create services to increase the interoperability in this area. 相似文献
99.
Enrique Castillo Aida Calviño Santos Sánchez-Cambronero María Nogal Ana Rivas 《Computers & Operations Research》2013
In this paper we deal with the travel time reliability PUE (probabilistic user equilibrium) problem studied by Lo et al. (2006) [12] and Nie (2011) [15] and we propose an alternative model that assumes a location-scale family for the path travel times, whose means and variances are evaluated in terms of link travel times. This avoids the use of the central limit theorem and convolutions providing a flexible and simple alternative. Contrary to the most existing models that require path enumeration or an iterative method to add paths sequentially, we present a percentile system optimization in its two versions: with and without path enumeration. Two examples of applications, one of them real, are used to illustrate the power of the proposed method. The cpu times required to solve the problem seem reasonable. In addition, we answer an open question raised by Nie (2011) [15] about the permutability of percentiles and partial derivatives of route travel times with respect to route flows. A family of counterexamples is given to demonstrate that the two operations: (a) obtain percentiles and (b) partial derivation of route travel times do not commute. Finally, to reproduce the trial-and-error sequence followed by users when selecting paths, we also present an algorithm that simulates this iterative process and shows that the final long-term user behavior coincides with PUE (probabilistic user equilibrium) problem resulting from some existing models. 相似文献
100.
In this paper a review of type-2 fuzzy logic applications in pattern recognition, classification and clustering problems is presented. Recently, type-2 fuzzy logic has gained popularity in a wide range of applications due to its ability to handle higher degrees of uncertainty. In particular, there have been recent applications of type-2 fuzzy logic in the fields of pattern recognition, classification and clustering, where it has helped improving results over type-1 fuzzy logic. In this paper a concise and representative review of the most successful applications of type-2 fuzzy logic in these fields is presented. 相似文献