全文获取类型
收费全文 | 65752篇 |
免费 | 6323篇 |
国内免费 | 3786篇 |
专业分类
电工技术 | 4513篇 |
技术理论 | 1篇 |
综合类 | 6468篇 |
化学工业 | 10483篇 |
金属工艺 | 3501篇 |
机械仪表 | 3789篇 |
建筑科学 | 5032篇 |
矿业工程 | 1729篇 |
能源动力 | 1462篇 |
轻工业 | 8582篇 |
水利工程 | 1482篇 |
石油天然气 | 2434篇 |
武器工业 | 678篇 |
无线电 | 6967篇 |
一般工业技术 | 6424篇 |
冶金工业 | 2454篇 |
原子能技术 | 727篇 |
自动化技术 | 9135篇 |
出版年
2024年 | 352篇 |
2023年 | 1125篇 |
2022年 | 2277篇 |
2021年 | 2864篇 |
2020年 | 2207篇 |
2019年 | 1736篇 |
2018年 | 1803篇 |
2017年 | 2036篇 |
2016年 | 1902篇 |
2015年 | 2783篇 |
2014年 | 3707篇 |
2013年 | 4168篇 |
2012年 | 4870篇 |
2011年 | 5357篇 |
2010年 | 4939篇 |
2009年 | 4668篇 |
2008年 | 4817篇 |
2007年 | 4475篇 |
2006年 | 4089篇 |
2005年 | 3297篇 |
2004年 | 2371篇 |
2003年 | 1864篇 |
2002年 | 1890篇 |
2001年 | 1565篇 |
2000年 | 1228篇 |
1999年 | 846篇 |
1998年 | 543篇 |
1997年 | 398篇 |
1996年 | 388篇 |
1995年 | 326篇 |
1994年 | 208篇 |
1993年 | 157篇 |
1992年 | 123篇 |
1991年 | 108篇 |
1990年 | 69篇 |
1989年 | 63篇 |
1988年 | 59篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 24篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1959年 | 5篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
91.
周莹 《电脑编程技巧与维护》2013,(8):28-30
基于统计的系统聚类分析是一种重要的数据挖掘算法。研究了一种多重系统聚类模型及其算法实现,把变量聚类和样本聚类相结合,并使用了两种方法赋值样本数据阵,使聚类结果更加直观。 相似文献
92.
采用NUC100LE3AN为主控芯片,设计了通用文本型HMI(Human Machine Interface),实现了与大部分品牌PLC的通信连接。介绍了该装置的构架原理、功能及其软硬件设计思想。详细讨论了FLASH存储器空间分配、APROM区与LDROM相互跳转原理、以及应用程序区任务模块的组织形式等。最后通过与信捷XC1-32型PLC连接,进行了功能测试,结果表明设计满足了功能需求。 相似文献
93.
Collision and intersection detection of surfaces is an important problem in computer graphics and robotic engineering. A key idea of our paper is to use the bracket method to derive the necessary and sufficient conditions for the collision of two ruled surfaces. Then the numerical intersection curve can be characterized. The cases for two bounded ruled surfaces are also discussed. 相似文献
94.
Wang JX Liao SH Zhu XH Wang Y Ling CX Ding X Fang YM Zhang XH 《Computer methods and programs in biomedicine》2011,104(3):472-479
This paper presents an intuitive nose surgery planning and simulation system, using 3D laser scan image and lateral X-ray image, to provide high quality prediction of the postoperative appearance, and design the patient specific prosthesis model automatically. After initial registration, the internal surface of soft tissue at the nose region was generated by the statistical data for soft tissue thickness adapted by the individual thickness information from the X-ray image. Then, the sketch contour of the 3D scan data on the lateral X-ray image was modified manually or adjusted automatically according to some aesthetic statistical data, to drive the simulation in real time by the state-of-the-art Laplacian surface deformation method. When satisfied with the 3D postoperative appearance, the deformation was mapped to the internal surface of soft tissue, and the change before and after simulation was utilized to generate the patient specific prosthesis model automatically. The surgeons who used the system confirmed that this planning system is attractive and has potential for daily clinical practice. 相似文献
95.
基于测定推进剂A现有分析方法准确度低,神经网络法对仪器要求高等不足,提出了的一种新的分析方法。该方法利用已知酸的电位滴定数据建立多元线性回归数学模型,利用化学因子分解该模型,对未知样进行浓度测定。实际测定结果表明本方法的最大分析误差不超过0.17%,标准偏差不超过1.9%,满足样品分析要求。 相似文献
96.
97.
98.
99.
In this paper, Adjusted Rand Index (ARI) is generalized to two new measures based on matrix comparison: (i) Adjusted Rand Index between a similarity matrix and a cluster partition (ARImp), to evaluate the consistency of a set of clustering solutions with their corresponding consensus matrix in a cluster ensemble, and (ii) Adjusted Rand Index between similarity matrices (ARImm), to evaluate the consistency between two similarity matrices. Desirable properties of ARI are preserved in the two new measures, and new properties are discussed. These properties include: (i) detection of uncorrelatedness; (ii) computation of ARImp/ARImm in a distributed environment; and (iii) characterization of the degree of uncertainty of a consensus matrix. All of these properties are investigated from both the perspectives of theoretical analysis and experimental validation. We have also performed a number of experiments to show the usefulness and effectiveness of the two proposed measures in practical applications. 相似文献
100.
In breast cancer research, it is of great interest to identify genomic markers associated with prognosis. Multiple gene profiling studies have been conducted for such a purpose. Genomic markers identified from the analysis of single datasets often do not have satisfactory reproducibility. Among the multiple possible reasons, the most important one is the small sample sizes of individual studies. A cost-effective solution is to pool data from multiple comparable studies and conduct integrative analysis. In this study, we collect four breast cancer prognosis studies with gene expression measurements. We describe the relationship between prognosis and gene expressions using the accelerated failure time (AFT) models. We adopt a 2-norm group bridge penalization approach for marker identification. This integrative analysis approach can effectively identify markers with consistent effects across multiple datasets and naturally accommodate the heterogeneity among studies. Statistical and simulation studies demonstrate satisfactory performance of this approach. Breast cancer prognosis markers identified using this approach have sound biological implications and satisfactory prediction performance. 相似文献