全文获取类型
收费全文 | 2139篇 |
免费 | 29篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 38篇 |
综合类 | 1篇 |
化学工业 | 419篇 |
金属工艺 | 51篇 |
机械仪表 | 50篇 |
建筑科学 | 57篇 |
矿业工程 | 6篇 |
能源动力 | 36篇 |
轻工业 | 158篇 |
水利工程 | 15篇 |
石油天然气 | 23篇 |
武器工业 | 1篇 |
无线电 | 197篇 |
一般工业技术 | 299篇 |
冶金工业 | 472篇 |
原子能技术 | 18篇 |
自动化技术 | 329篇 |
出版年
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 26篇 |
2016年 | 28篇 |
2015年 | 20篇 |
2014年 | 46篇 |
2013年 | 108篇 |
2012年 | 68篇 |
2011年 | 80篇 |
2010年 | 52篇 |
2009年 | 47篇 |
2008年 | 62篇 |
2007年 | 78篇 |
2006年 | 81篇 |
2005年 | 67篇 |
2004年 | 70篇 |
2003年 | 54篇 |
2002年 | 59篇 |
2001年 | 57篇 |
2000年 | 62篇 |
1999年 | 69篇 |
1998年 | 113篇 |
1997年 | 82篇 |
1996年 | 64篇 |
1995年 | 61篇 |
1994年 | 58篇 |
1993年 | 43篇 |
1992年 | 38篇 |
1991年 | 40篇 |
1990年 | 39篇 |
1989年 | 31篇 |
1988年 | 33篇 |
1987年 | 22篇 |
1986年 | 20篇 |
1985年 | 27篇 |
1984年 | 25篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1976年 | 16篇 |
1975年 | 18篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1970年 | 12篇 |
排序方式: 共有2170条查询结果,搜索用时 0 毫秒
31.
Wayne O’Brien Author Vitae 《Journal of Systems and Software》2008,81(11):1997-2013
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them. 相似文献
32.
This paper describes a method for temporally calibrating video sequences from unsynchronized cameras by image processing operations, and presents two search algorithms to match and align trajectories across different camera views. Existing multi-camera systems assume that input video sequences are synchronized either by genlock or by time stamp information and a centralized server. Yet, hardware-based synchronization increases installation cost. Hence, using image information is necessary to align frames from the cameras whose clocks are not synchronized. The system built for temporal calibration is composed of three modules: object tracking module, calibration data extraction module, and the search module. A robust and efficient search algorithm is introduced that recovers the frame offset by matching the trajectories in different views, and finding the most reliable match. Thanks to information obtained from multiple trajectories, this algorithm is robust to possible errors in background subtraction and location extraction. Moreover, the algorithm can handle very large frame offsets. A RANdom SAmple Consensus (RANSAC) based version of this search algorithm is also introduced. Results obtained with different video sequences are presented, which show the robustness of the algorithms in recovering various range of frame offsets for video sequences with varying levels of object activity. 相似文献
33.
Atsushi Kawamoto 《Structural and Multidisciplinary Optimization》2009,37(4):429-433
This paper deals with the design of compliant mechanisms in a continuum-based finite-element representation. Because the displacements
of mechanisms are intrinsically large, the geometric nonlinearity is essential for designing such mechanisms. However, the
consideration of the geometric nonlinearity may cause some instability in topology optimization. The problem is in the analysis
part but not in the optimization part. To alleviate the analysis problem and eventually stabilize the optimization process,
this paper proposes to apply the Levenberg–Marquardt method to the nonlinear analysis of compliant mechanisms. 相似文献
34.
Summary The nature of the excited state interactions in poly(ethylene terephthalate) is still subject to debate. We study a new series of model compounds composed of a central terephthaloyl group condensed with -hydroxy--phenyl-n-alkanes. Although the molecular architecture prevents these molecules from achieving symmetric ring-ring overlap, the steady-state fluorescence spectra are remarkably similar to those of other models studied earlier, where such overlap was expected. The solvent polarity dependence suggests that the excited state complex is an exciplex and not an excimer. 相似文献
35.
A Review of Metal Fabricated with Laser‐ and Powder‐Bed Based Additive Manufacturing Techniques: Process,Nomenclature, Materials,Achievable Properties,and its Utilization in the Medical Sector 下载免费PDF全文
36.
The in-situ monitoring of the living carbocationic polymerization of isobutylene (IB) and styrene (St) with a fiber optic
Attenuated Total Reflection (ATR) probe in the mid-IR "fingerprint" range is reported here for the first time. Monomer consumption
was followed by the disappearance of the C=C stretching for both IB and St, and the C−H bending of the CH3-group in IB. The formation of polyisobutylene (PIB) was also monitored by tracing the asymmetrical doublet characteristic
of C−H bending of the t-butyl groups of the PIB. Conversion measurements by conventional off-line gravimetry correlated well with the new technique.
Received: 27 August 1997/Revised version: 2 November 1997/Accepted: 20 November 1997 相似文献
37.
Summary Catechin binds strongly to both poly(vinylpyrrolidone) and poly(L-proline) in dilute aqueous solution, inducing a collapse of the more flexible poly(vinylpyrrolidone) chains, but forming a microgel with the more extended poly(L-proline) chains. Low concentrations of poly(L-proline) inhibit the discoloration of aqueous solutions of catechin, thereby implicating the ortho hydroxyyl groups in the catechol moiety in the binding process. Modeling shows that the likely binding sites on poly(L-proline) arise from two minor local conformations. These minor conformations are less frequent in poly(-hydroxy-L-proline) than in poly(L-proline), which may explain why catechin interacts more strongly with poly(L-proline) than with poly(-hydroxy-L-proline). 相似文献
38.
39.
40.
Multi-Modal Dialog Scene Detection Using Hidden Markov Models for Content-Based Multimedia Indexing 总被引:1,自引:1,他引:0
A class of audio-visual data (fiction entertainment: movies, TV series) is segmented into scenes, which contain dialogs, using a novel hidden Markov model-based (HMM) method. Each shot is classified using both audio track (via classification of speech, silence and music) and visual content (face and location information). The result of this shot-based classification is an audio-visual token to be used by the HMM state diagram to achieve scene analysis. After simulations with circular and left-to-right HMM topologies, it is observed that both are performing very good with multi-modal inputs. Moreover, for circular topology, the comparisons between different training and observation sets show that audio and face information together gives the most consistent results among different observation sets. 相似文献