全文获取类型
收费全文 | 4726篇 |
免费 | 213篇 |
国内免费 | 878篇 |
专业分类
林业 | 298篇 |
农学 | 537篇 |
基础科学 | 1274篇 |
1132篇 | |
综合类 | 2090篇 |
农作物 | 64篇 |
水产渔业 | 99篇 |
畜牧兽医 | 119篇 |
园艺 | 38篇 |
植物保护 | 166篇 |
出版年
2024年 | 43篇 |
2023年 | 115篇 |
2022年 | 192篇 |
2021年 | 220篇 |
2020年 | 187篇 |
2019年 | 239篇 |
2018年 | 146篇 |
2017年 | 191篇 |
2016年 | 230篇 |
2015年 | 214篇 |
2014年 | 242篇 |
2013年 | 266篇 |
2012年 | 394篇 |
2011年 | 378篇 |
2010年 | 339篇 |
2009年 | 319篇 |
2008年 | 253篇 |
2007年 | 291篇 |
2006年 | 287篇 |
2005年 | 234篇 |
2004年 | 190篇 |
2003年 | 122篇 |
2002年 | 129篇 |
2001年 | 113篇 |
2000年 | 75篇 |
1999年 | 61篇 |
1998年 | 53篇 |
1997年 | 44篇 |
1996年 | 52篇 |
1995年 | 44篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1992年 | 31篇 |
1991年 | 17篇 |
1990年 | 23篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有5817条查询结果,搜索用时 31 毫秒
41.
The FCBP(Fuzzy calculating BP) algorithm which is proposed by this paper hasovercome the sensitivity for samples,reduced the number of input layer's samples,lightened the burden of input layer.it is suitable to fuzzy inference and pattern recognition. 相似文献
42.
A novel edge detection algorithm is proposed by implementing fuzzy image enhancement at different scales.The implement of this algorithm can reduce the negative influence bring from the non-maximum suppression algorithm which select only one threshold.The success of the approach depends on the selection of a general fuzzy operator(GFO) for the enhancement of contrast of region after smoothing of image at different scales.Consequently,it is more obvious that coarse intensity changes are obtained at a large scale whereas the fine details of intensity changes are obtained at a small scale.A pretty performance is obtained by used this work. 相似文献
43.
ZHANG Xin-yan 《保鲜与加工》2004,(5):54-56
While design the fuzzy controller, it is very important to determine the membership function of fuzzy variables.The data can be broadly classified as fuzzy sets by using the classification property of the BP neural network. The author selects a BP neural network with one hide layer and uses S function to the input and hide layer, and linear function to the output layer.Advanced BP algorithm isused to train the BP neural network in the environment of MATLAB . The nearer to the target values is the better the last output is.With the trained BP network , the membership values of the inputs can be got ten. This method has high rate and low error. 相似文献
44.
Ye Xiaoming Liu Dongyan 《保鲜与加工》1997,(2):12-20
This paper presents a series of targets which are usefull for engineering.The paper also presents an adaptive weight function according to the fail mechanism of rockmass and a fuzzy aynthetic evaluation medel on rockmass blast ability.The model is applied to evaluate the blast ability of rockmass in an engineering and the result shows that the model is effective. 相似文献
45.
46.
This poper sets up a new Neural Network Fuzzy inference Cooperation system which is based on fuzzy inference principle in Expert Systems,take advantage of the powerful learning function, the little sensitivity to input layer's samples,and the fast convergence and so on in FCBP and take advantage of the good sort property and good suit property to fuzzy value in MFART Network. 相似文献
47.
The inherent fault tolerance of multilayer neural networks (MLNs) is due to thedistributed properties of information processing and information storage in an MLN , and the inher-ent fault-masking capability of every neuron. Also,the concept of inherent fault tolerance of MLNsis formalized, Finally, perceptrons and three-layer nets are shown inherently fault tolerant underreasonable statistical conditions,respectively. 相似文献
48.
Based on experience in customer service evaluation,through the analysis of many factors affecting customer satisfaction calculation estimate, customer service evaluation rules as well as customer-oriented and supply chain partner-oriented methods are developed and discussed from the view of supply chain, besides, we construct two sets of customer satisfaction evaluation systems, in which we perform non-dimensional analysis on evaluation system to form single factor evaluation matrix after using improved AHP to determine each factor item's weighting ,utilizing fuzzy decision theory to construct evaluation model for integrated estimate. This evaluation method is scientific, round and objective with more stability and convienience in practical use. 相似文献
49.
Fingerprint classification can provide an important indexing mechanism in a fingerprint database. An accurate and consistent classification can greatly reduce fingerprint matching time for large database. In the paper, by combining genetic algorithm and neural network is presented a fingerprint classification algorithm which is able to achieve an accurate classification. By inputting the global feature represented by directional image to three layer neural network trained by genetic algorithm, the fingerprints were classified into six categories: whorl, right loop, left loop, arch, double loop and undiscerning type successfully. 相似文献
50.
The Crossing Entropy is defined to scale the similar level of two probability distribution. In many papers on learning BN structure,the Crossing Entropy was used as an indicator of measuring the learning accuracy of an algorithm.The known scoring metrics for learning BN structure is analyzed in this paper,then a new scoring metrics Sum of Mutual Information is proposed based on the information theory.At last,two algorithm for learning BN structure by SIM is represented. 相似文献