全文获取类型
收费全文 | 672篇 |
免费 | 34篇 |
国内免费 | 2篇 |
专业分类
综合类 | 2篇 |
化学工业 | 96篇 |
金属工艺 | 12篇 |
机械仪表 | 10篇 |
建筑科学 | 19篇 |
能源动力 | 9篇 |
轻工业 | 62篇 |
水利工程 | 2篇 |
无线电 | 191篇 |
一般工业技术 | 121篇 |
冶金工业 | 88篇 |
原子能技术 | 1篇 |
自动化技术 | 95篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 23篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 13篇 |
2014年 | 14篇 |
2013年 | 32篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 24篇 |
2009年 | 15篇 |
2008年 | 25篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 22篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 23篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 25篇 |
1997年 | 30篇 |
1996年 | 19篇 |
1995年 | 10篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 7篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1967年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有708条查询结果,搜索用时 15 毫秒
1.
Salim Hengky K. Padfield Rory Lee Chew Tin Syayuti Khadijah Papargyropoulou Effie Tham Mun Hou 《Clean Technologies and Environmental Policy》2018,20(3):529-538
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food... 相似文献
2.
PJ Jenkins MA Satta M Simmgen WM Drake C Williamson DG Lowe K Britton SL Chew RV Thakker GM Besser 《Canadian Metallurgical Quarterly》1997,47(6):747-751
We report a patient with a metastatic parathyroid carcinoma and medullary carcinoma of the thyroid. This patient represents a variation of the multiple endocrine neoplasia syndrome (MEN) type 2A. There was no evidence of a phaeochromocytoma. The case illustrates the difficulties that may be encountered in localising the source of PTH secretion; the patient underwent four unsuccessful exploratory operations of the neck and mediastinum before further investigations revealed a single metastatic deposit of parathyroid carcinoma involving the first thoracic vertebra. PCR amplification and sequencing of the RET oncogene from the metastatic parathyroid carcinoma and genomic DNA revealed a heterozygous mutation (Cys634Tyr) in exon 11, as has previously been described to occur in MEN 2A. In addition, loss of tumour heterozygosity was demonstrated at loci from chromosomes 1, 2, 3p, 13q and 16p. This represents the first report of a parathyroid carcinoma in a MEN2A patient, in which the multiple allelic deletions are consistent with the generalised losses observed in aggressive tumours. 相似文献
3.
The nature of damage produced by low energy Ar+ ion and Ar atom milling in the II–VI semiconductors CdTe, ZnS and ZnSe is studied in detail by conventional and high resolution transmission electron microscopy. It is demonstrated that the damage consists of dense arrays of small dislocation loops near to each milled surface. When ion or atom milling of this type is used for thin specimen preparation prior to microscopy the loop arrays can seriously obscure images and so complicate their interpretation. This problem concerning the presence of artifactual defects can be greatly reduced by the use of reactive I+ ion milling for specimen thinning and, in the case of CdTe, spurious dislocation loop formation can be completely suppressed. 相似文献
4.
Qing-Huo Liu Anderson B. Weng Cho Chew 《Geoscience and Remote Sensing, IEEE Transactions on》1994,32(3):494-498
The authors formulate and implement a numerical mode-matching (NMM) method to model electrode-type resistivity tools in invaded thin beds. The authors derive the low-frequency approximation of the Maxwell's equations to obtain the partial differential equation for the potential field. The new NMM program is validated by comparing the numerical results with those obtained from other dc programs. It is found that this new program is much faster than the program using the finite-element method (FEM), and hence is useful for routine interpretation of resistivity logs and for inversion 相似文献
5.
An extensive and systematic search strategy to determine the conformational profile of 12 cyclic disulfide-bridged opioid peptides with varying affinities at the delta receptor has been carried out to identify the structure that is recognized by the delta receptor for each analogue. The methods and procedures used here for the conformational search have already been validated for [D-Pen2,D-Pen5] enkephalin (DPDPE), one member of this family. Use of these methods led to a low-energy solution conformation of DPDPE in excellent agreement with all the geometric properties deduced from its solution nmr spectra. Each of the analogue was subjected to the same procedure, involving a combination of molecular dynamics simulations at high and low temperature. The study was repeated in two environmental conditions, an apolar environment, simulated by using a distance-dependent dielectric constant, and a polar environment by embedding the peptides in a high constant dielectric (epsilon = 80). An automated comparison of the different conformers based on their backbone rms and average distance between the key aromatic moieties was followed by graphic analysis using maximum structural overlap. The cross-comparison of the conformations for each analogue revealed a unique conformer that may be recognized by the delta receptor for each high-affinity analogue that permitted maintaining the critical elements required for recognition in a simple spatial orientation, while maximizing similarity in other regions. 相似文献
6.
In this letter, we report on the electrical characteristic and the comparison of the metal-insulator-metal (MIM) capacitors with PECVD silicon nitride (SiN) and silicon oxynitride (SiON). Both capacitors are found to exhibit low leakage and high breakdown field strength, as well as absence of dispersive behavior, good linearity, and comparable quality factor behaviors. 相似文献
7.
Sarkar M. Ang Chew Hoe Huang Jiayi Chen T.P. 《Electron Devices, IEEE Transactions on》2005,52(6):1200-1204
In a MOSFET, a nonuniform, graded vertical dopant profile in the polysilicon gate causes a potential drop at the polysilicon/oxide interface. In this paper, the effect of this potential drop on the gate leakage current has been evaluated for the first time. The extent of variations of this affected gate leakage current with gate oxide thickness, gate length, and gate and drain bias conditions have been assessed with device simulation for an nMOS at 0.13 /spl mu/m low-voltage process. The results provide a guideline to the severity of this effect from the point of view of device and circuit operation and standby power consumption. 相似文献
8.
Huang L. Chew K. A. Thilakawardana S. Liu Y. Moessner K. Tafazolli R. 《Broadcasting, IEEE Transactions on》2006,52(4):492-504
Recently, an upsurge of interest has been observed in providing multimedia on-demand (MoD) services to mobile users over wireless networks. Nevertheless, due to the rapidly varying nature of mobile networks and the scarcity of radio resources, the commercial implementation is still limited. This paper presents an efficient group-based multimedia-on-demand (GMoD) service model over multicast-enabled wireless infrastructures, where users requesting the same content are grouped and served simultaneously with a single multicast stream. The grouping is fulfilled through a process named "batching". An analytical model is derived to analyse a timeout-based batching scheme with respect to the tradeoff between user blocking probability and reneging probability. Based on the deduced analytical model, an optimal timeout-based batching scheme is proposed to dynamically identify the optimal tradeoff point that maximizes the system satisfaction ratio given a particular system status. The proposed scheme is evaluated by means of simulation and compared with two basic batching schemes (timeout-based, size-based), and two hybrid ones (combined-for-profit, combined-for-loss). The simulation results demonstrate the proposed approach can ensure significant gains in terms of user satisfaction ratio, with low reneging and blocking probabilities 相似文献
9.
S. Kumar Author Vitae Author Vitae S. Ranganath Author Vitae Author Vitae F.T. Chew Author Vitae 《Pattern recognition》2006,39(6):1088-1098
This paper presents a robust rule-based approach for the splitting of binary clumps that are formed by objects of diverse shapes and sizes. First, the deepest boundary pixels, i.e., the concavity pixels in a clump, are detected using a fast and accurate scheme. Next, concavity-based rules are applied to generate the candidate split lines that join pairs of concavity pixels. A figure of merit is used to determine the best split line from the set of candidate lines. Experimental results show that the proposed approach is robust and accurate. 相似文献
10.
The distorted Born iterative method (DBIM) is used to solve two-dimensional inverse scattering problems, thereby providing another general method to solve the two-dimensional imaging problem when the Born and the Rytov approximations break down. Numerical simulations are performed using the DBIM and the method proposed previously by the authors (Int. J. Imaging Syst. Technol., vol.1, no.1, p.100-8, 1989) called the Born iterative method (BIM) for several cases in which the conditions for the first-order Born approximation are not satisfied. The results show that each method has its advantages; the DBIM shows faster convergence rate compared to the BIM, while the BIM is more robust to noise contamination compared to the DBIM. 相似文献