全文获取类型
收费全文 | 14088篇 |
免费 | 382篇 |
国内免费 | 801篇 |
专业分类
系统科学 | 829篇 |
丛书文集 | 859篇 |
教育与普及 | 247篇 |
理论与方法论 | 89篇 |
现状及发展 | 46篇 |
综合类 | 13201篇 |
出版年
2024年 | 41篇 |
2023年 | 142篇 |
2022年 | 160篇 |
2021年 | 178篇 |
2020年 | 179篇 |
2019年 | 213篇 |
2018年 | 108篇 |
2017年 | 160篇 |
2016年 | 208篇 |
2015年 | 313篇 |
2014年 | 610篇 |
2013年 | 561篇 |
2012年 | 631篇 |
2011年 | 723篇 |
2010年 | 808篇 |
2009年 | 864篇 |
2008年 | 1256篇 |
2007年 | 1068篇 |
2006年 | 767篇 |
2005年 | 716篇 |
2004年 | 612篇 |
2003年 | 612篇 |
2002年 | 552篇 |
2001年 | 492篇 |
2000年 | 447篇 |
1999年 | 340篇 |
1998年 | 304篇 |
1997年 | 294篇 |
1996年 | 333篇 |
1995年 | 291篇 |
1994年 | 229篇 |
1993年 | 196篇 |
1992年 | 185篇 |
1991年 | 154篇 |
1990年 | 136篇 |
1989年 | 172篇 |
1988年 | 88篇 |
1987年 | 64篇 |
1986年 | 31篇 |
1985年 | 12篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1965年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
汪继南 《上饶师范学院学报》2004,24(5):108-112
对CSSCI引文数据和中国期刊网引文数据进行比较,探讨经过来源期刊选择的CSSCI引文和未经过选择因而范围更广的中国期刊网引文评价的排序耦合性并作出相关分析。对CSSCI用于引文评价需完善之处提出建议。 相似文献
983.
CHENLei ZHOUGuo-fu 《武汉大学学报:自然科学英文版》2004,9(5):845-850
In this paper, we present a strategy to implement multi pose face detection in compressed domain. The strategy extracts firstly feature vectors from DCT domain, and then uses a boosting algorithm to build classifiers to distinguish faces and non-faces. Moreover. to get more accurate results of the face detection, we present a kernel function and a linear combination to build incrementally the strong classifiers based on the weak classifiers. Through comparing and analyzing results of some experiments on the synthetic data and the natural data, we can get more satisfied results by the strong classifiers than by the weak classifies. 相似文献
984.
This research considers the mathematical relationship between concentration of Chla and seven environmental factors, i.e. Lake water temperature (T), Secci-depth (SD), pH, DO, CODMn, Total Nitrogen (TN), Total Phosphorus (TP). Stepwise linear regression of 1997 to 1999 monitoring data at each sampling point of Qiandaohu Lake yielded the multivariate regression models presented in this paper. The concentration of Chla as simulation for the year 2000 by the regression model was similar to the observed value. The suggested mathematical relationship could be used to predict changes in the lakewater environment at any point in time. The results showed that SD, TP and pH were the most significant factors affecting Chla concentration. 相似文献
985.
986.
Zhang F 《浙江大学学报(自然科学英文版)》2004,5(5):558-566
This paper provides theoretical foundation tor the problem ot localization in multi-robot formations. Sufficient and necessary conditions for completely localizing a formation of mobile robots/vehicles in SE(2) based on distributed sensor networks and graph rigidity are proposed. A method for estimating the quality of localizations via a linearized weighted least-squares algorithm is presented, which considers incomplete and noisy sensory information. The approach in this paper had been implemented in a multi-robot system of five car-like robots equipped with omni-directional cameras and IEEE 802.11b wireless network. 相似文献
987.
Residue-residue contacts are very important in forming protein structure. In this work, we calculated the average probability of residue-residue contacts in 470 globular proteins and analyzed the distribution of contacts in the different interval of residues using Contacts of Structural Units (CSU) and Structural Classification (SCOP) software. It was found that the relationship between the average probability PL and the residue distance L for four structural classes of proteins could be expressed as lgPL=a+b x L, where a and b are coefficients. We also discussed the connection between two aspects of proteins which have equal array residue number and found that the distribution probability was stable (or un-stable) if the proteins had the same (or different) compact (for example synthase) in the same structural class. 相似文献
988.
作者讨论了线性Fuzzy邻域空间中的层次结构,得到以下结果:⑴线性Fuzzy邻域空间(X,△)局部n-凸当且仅当其各层拓扑线性空间局部凸;⑵线性Fuzzy邻域空间(X,△)是(QL)型Fuzzy拓扑线性空间当且仅当其为诱导空间。 相似文献
989.
运用Photoshop软件处理图像时,“选取”是首要的也是至关重要的五。本文根据艺术设计实际运用情况,对于选取的方法进行了多方面的探索和总结。 相似文献
990.