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991.
We consider a wireless multimedia code-division multiple-access system, in which the terminals transmit at different rates. We formulate the problem as a constrained optimization problem, with the objective of maximizing the total effective rate. An optimal power control strategy is derived. When the scale of the system is large, the optimal solution takes a simple form, which is easy to be applied practically. Furthermore, our basic model can be extended to include delay-sensitive traffic  相似文献   
992.
用超对称幺正变换解具有逆场算符的Jaynes—Cummings模型   总被引:4,自引:0,他引:4  
对于具有逆场算符的Jaynes-Cummings Hamiltonian,我们发现了它的超对称结构,并应用超对称幺正变换的方法将其对角化,从而得到了它的本征值、本征态,同时也计算了态的演化和跃迁几率。  相似文献   
993.
Networks are currently being deployed to provide dedicated channels to support large data transfers and stable control flow needed in large-scale scientific applications. We present experimental results on application-level throughputs achievable on such channels using a range of hosts and dedicated connections. These results high-light the throughput limitations in several cases due to host issues, including disk and file system speeds, processor scheduling and loads, and complexity of internal data paths. We characterize such effects using the notion of host-bandwidth, which must be considered together with the connection-bandwidth in designing and optimizing transport protocols for dedicated channels. We propose a new transport protocol implementation, named Hurricane, to achieve high utilization of dedicated channels. While the overall protocol is quite similar to existing UDP-based protocols, new parameters, such as group size of NACKS, are identified and carefully optimized to achieve high channel utilization. Our end hosts consist of workstations, a cluster and Cray X1 supercomputer. Between two workstations, we consider: (A) 1 Gbps layer 3 connection of several hundred miles, and (B) 10 Gbps layer 2 connection of several thousand miles. Between Cray X1 and the cluster, we consider: (C) 450 Mbps layer 3 channel provisioned by policy, and (D) 1 Gbps layer 2 connection provisioned over an mpls tunnel.  相似文献   
994.
This paper presents, for the first time, the design of a size-reduced rectangular patch hybrid coupler. Different types of compact rectangular patch hybrid couplers with different ground plane patterns are described. For demonstration, two compact rectangular patch hybrid couplers are designed to operate at 3.5 GHz. They are measured to have 30.1% and 33.3% bandwidth with 67.3% and 72.3% size reduction compared with the optimized one without patterned ground plane.  相似文献   
995.
[Correction Notice: An erratum for this article was reported in Vol 75(5) of Journal of Consulting and Clinical Psychology (see record 2007-13640-017). Coauthor Joseph L. Fava's affiliation was incorrect and should list Brown University Medical School/The Miriam Hospital.] Several recent studies suggest that daily weighing is important for long-term weight control, but concerns have been raised about possible adverse psychological effects. The "STOP Regain" clinical trial provides a unique opportunity to examine this issue both cross-sectionally and prospectively. Successful weight losers (N = 314) were randomly assigned to a control or to a face-to-face or Internet intervention designed to help them maintain their weight loss and were then followed for 18 months. The intervention groups reported increases in daily self-weighing, which were associated with successful weight loss maintenance. We found no evidence that increases in frequency of weighing or daily weighing per se had any adverse effects in this study population. Rather, increases in self-weighing were associated with increases in dietary restraint (p  相似文献   
996.
A novel approach to perform a high number of individual polymerase chain reactions (PCR) in microcapsule reaction compartments, termed “Microcapsule‐PCR” was developed. Temperature stable microcapsules with a selective permeable capsule wall were constructed by matrix‐assisted layer‐by‐layer (LbL) Encapsulation technique. During the PCR, small molecular weight building blocks – nucleotides (dNTPs) were supplied externally and diffuse through the permeable capsule wall into the interior, while the resulted high molecular weight PCR products were accumulated within the microcapsule. Microcapsules (∼110.8 µm average diameter) filled with a PCR reaction mixture were constructed by an emulsion technique having a 2% agarose core and a capsule formed by LbL coating with poly(allylamine‐hydrochloride) and poly(4‐styrene‐sulfonate). An encapsulation efficiency of 47% (measured for primer‐FITC (22 bases)) and 98% PCR efficiency was achieved. Microcapsules formed by eight layers of polyelectrolyte and subjected to PCR cycling (up to 95 °C) demonstrated good temperature stability without any significantly changes in DNA retention yield and microcapsule morphology. A multiplex Microcapsule‐PCR experiment demonstrated that microcapsules are individual compartment and do not exchange templates or primers between microcapsules during PCR cycling.  相似文献   
997.
998.
Reports an error in the original article by M. T. McGuire et al (Journal of Consulting and Clinical Psychology, 1999[Apr], 67[2], 177–185). On page 181, the Figure 1 caption was incorrect. The correct caption is provided. (The following abstract of this article originally appeared in record 1999-10771-002.) This study identified predictors of weight gain versus continued maintenance among individuals already successful at long-term weight loss. Weight, behavior, and psychological information was collected on entry into the study and 1 year later. Thirty-five percent gained weight over the year of follow-up, and 59% maintained their weight losses. Risk factors for weight regain included more recent weight losses (less than 2 years vs. 2 years or more), larger weight losses (greater than 30% of maximum weight vs. less than 30%), and higher levels of depression, dietary disinhibition, and binge eating levels at entry into the registry. Over the year of follow-up, gainers reported greater decreases in energy expenditure and greater increases in percentage of calories from fat. Gainers also reported greater decreases in restraint and increases in hunger, dietary disinhibition, and binge eating. … (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
999.
The aim of this study is to investigate current parental support for student learning with information technology (IT) in Hong Kong. A total of 3340 and 3656 parents and 539 and 440 primary school heads responded to two surveys in 2005/06 and 2006/07, respectively, in this cross-sectional study. The results show a persistent positive perception of and support for IT among educators and parents, which signify a solid foundation for the extension of student learning from the classroom to the home environment. The high level of expectation among school heads for parental support reflects the need for schools to initiate cooperation with parents to extend IT-supported learning to the home setting. The shift in parental apprehension from worry over the provision of IT facilities to worry over the cultivation of proper attitudes toward the use of IT reveals the importance of fostering information literacy in home–school collaboration.  相似文献   
1000.
Based on the linear prediction property of sinusoidal signals, two constrained weighted least squares frequency estimators for multiple real sinusoids embedded in white noise are proposed. In order to achieve accurate frequency estimation, the first algorithm uses a generalized unit-norm constraint, while the second method employs a monic constraint. The weighting matrices in both methods are a function of the frequency parameters and are obtained in an iterative manner. For the case of a single real tone with sufficiently large data samples, both estimators provide nearly identical frequency estimates and their performance approaches Crame/spl acute/r-Rao lower bound (CRLB) for white Gaussian noise before the threshold effect occurs. Algorithms for closed-form single-tone frequency estimation are also devised. Computer simulations are included to corroborate the theoretical development and to contrast the estimator performance with the CRLB for different frequencies, observation lengths and signal-to-noise ratio (SNR) conditions.  相似文献   
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