首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   299427篇
  免费   11956篇
  国内免费   6480篇
电工技术   9716篇
技术理论   7篇
综合类   9805篇
化学工业   41510篇
金属工艺   16324篇
机械仪表   13325篇
建筑科学   13686篇
矿业工程   4135篇
能源动力   7444篇
轻工业   17091篇
水利工程   4004篇
石油天然气   8222篇
武器工业   891篇
无线电   37918篇
一般工业技术   50965篇
冶金工业   32981篇
原子能技术   2881篇
自动化技术   46958篇
  2024年   603篇
  2023年   2246篇
  2022年   3958篇
  2021年   5534篇
  2020年   4233篇
  2019年   3789篇
  2018年   18309篇
  2017年   17806篇
  2016年   13988篇
  2015年   6127篇
  2014年   7328篇
  2013年   11495篇
  2012年   12904篇
  2011年   20729篇
  2010年   17907篇
  2009年   15526篇
  2008年   16713篇
  2007年   17548篇
  2006年   10039篇
  2005年   9917篇
  2004年   7943篇
  2003年   7357篇
  2002年   6208篇
  2001年   5811篇
  2000年   5762篇
  1999年   6221篇
  1998年   12052篇
  1997年   8401篇
  1996年   6839篇
  1995年   4940篇
  1994年   4241篇
  1993年   3768篇
  1992年   2489篇
  1991年   2276篇
  1990年   1990篇
  1989年   1739篇
  1988年   1524篇
  1987年   1098篇
  1986年   1051篇
  1985年   1012篇
  1984年   867篇
  1983年   741篇
  1982年   761篇
  1981年   720篇
  1980年   602篇
  1979年   486篇
  1978年   417篇
  1977年   533篇
  1976年   958篇
  1975年   299篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This study introduces delay independent decentralized guaranteed cost control design method based on two controller structures for nonlinear uncertain interconnected large scale systems with time delays. First, a set of equivalent Takagi-Sugeno (T-S) fuzzy models are extended to represent the systems. Then a decentralized state-feedback guaranteed cost performance controller is proposed for the fuzzy systems. Based on delay independent Lyapunov functional approach, some sufficient conditions for the existence of the controller can be cast into the feasible problem of LMIs irrespective of the sizes of the time delays so that the system can be asymptotically stabilized for all considered uncertainties whose sizes are not larger than their bounds. Finally, the minimizing approach is proposed to search the suboptimal upper bound value of guaranteed cost function. Moreover, the corresponding conditions are extended into the generalized dynamic output-feedback close-loop system. Finally, the better control performances of the proposed methods are shown by the simulation examples.  相似文献   
992.
In an underwater environment, measurements regarding true targets and false targets (clutter) can be made. Therefore, a suitable data association method to exactly detect and track a target and an efficient track initiation method for judging tracks formed by the target should be selected in this environment. This paper attempts to propose a new data association method and track initiation method to detect and track targets more effectively. Also, the performance of the new method is tested in a series of Monte Carlo simulation runs and is compared with the existing data association and track initiation methods in a cluttered environment.  相似文献   
993.
This paper deals with the problem of adaptive control of uncertain nonlinear port-controlled Hamiltonian systems subject to actuator saturation, and proposes a number of results on the control design. Firstly, the adaptive stabilization problem is studied, and a control design method is developed by using both the dissipative Hamiltonian structural and saturated actuator properties. Secondly, for the case that there are both parametric uncertainties and external disturbances in the AS systems, an adaptive H control design approach is presented. Finally, study of an example of power systems with simulations shows that the adaptive controller proposed in this paper is effective.  相似文献   
994.
Diabetes therapy management in AAL environments, such as old people and diabetes patients homes, is a very difficult task since many factors affect a patient’s blood sugar levels. Factors such as illness, treatments, physical and psychological stress, physical activity, drugs, intravenous fluids and change in the meal plan cause unpredictable and potentially dangerous fluctuations in blood sugar levels. Right now, operations related to dosage are based on insulin infusion protocol boards, which are provided by physicians to the patients. These boards are not considering very influential factors such as glycemic index from the diet, consequently patients need to estimate the dosage leading to dose error, which culminates in hyperglycemia and hypoglycemia episode. Therefore, right insulin infusion calculation needs to be supported by the next generation of personal-care devices. For this reason, a personal device has been developed to assist and consider more factors in the insulin therapy dosage calculation. The proposed solution is based on Internet of things in order to, on the one hand, support a patient’s profile management architecture based on personal RFID cards and, on the other hand, provide global connectivity between the developed patient’s personal device based on 6LoWPAN, nurses/physicians desktop application to manage personal health cards, glycemic index information system, and patient’s web portal. This solution has been evaluated by a multidisciplinary group formed by patients, physicians, and nurses.  相似文献   
995.
996.
Floor control refers to the need for coordinating activities occurred in synchronously cooperating applications shared among collaborators. We address this for ubiquitous collaboration—the capability of multiple users to link together with disparate access device anytime and anywhere. Floor control has been studied for years but most researchers focus on relaxed coordination mechanisms with stationary devices that allow updates by any user on any object and resolve the uncoordinated updates. In this paper we present a floor control mechanism, called XGSP-Floor, which implements a coordination mechanism at application level for enabling users to consistently share the same resource in real time (synchronous collaboration) in ubiquitous collaboration environment. The implementation platform on cell phone devices may not be new. But we believe the implementation and experiment for XGSP-Floor on cell phone devices is a new challenge in ubiquitous collaboration environment even though the coordination mechanism can intuitively impose a tremendous overhead in worst case. We also describe the results of the modeling of XGSP-Floor and formal verification to prove the correctness of the modeling using Colored Petri Nets. We describe lessons learned and discuss future work.  相似文献   
997.
998.
999.
This work processes linear prediction (LP) residual in the time domain at three different levels, extracts speaker information, and demonstrates their significance and also different nature for text-independent speaker recognition. The subsegmental analysis considers LP residual in blocks of 5 msec with shift of 2.5 msec to extract speaker information. The segmental analysis extracts speaker information by processing in blocks of 20 msec with shift of 2.5 msec. The suprasegmental speaker information is extracted by viewing in blocks of 250 msec with shift of 6.25 msec. The speaker identification and verification studies performed using NIST-99 and NIST-03 databases demonstrate that the segmental analysis provides best performance followed by subsegmental analysis. The suprasegmental analysis gives the least performance. However, the evidences from all the three levels of processing seem to be different and combine well to provide improved performance, demonstrating different speaker information captured at each level of processing. Finally, the combined evidence from all the three levels of processing together with vocal tract information further improves the speaker recognition performance.  相似文献   
1000.
In this paper we consider an adaptive control problem of finite DoF worm-like locomotion systems (WLLS) which contact the ground with Coulomb dry friction. Using a rough mathematical friction law the system is shown to belong to a system class that allows adaptive control. Gaits from the kinematic theory can be tracked by means of adaptive controllers. For this we introduce two different adaptive controllers for λ-tracking and focus on that one which is not based on the derivative of the output. We pay attention to the analysis of such systems and present some theoretical control investigations including proofs. Numerical simulations of tracking different reference signals under arbitrary choice of the system parameters demonstrate and illustrate that the introduced simple adaptive controllers work successfully and effectively. Current experiments are aimed at the justification of theoretical results.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号