全文获取类型
收费全文 | 382篇 |
免费 | 8篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 109篇 |
金属工艺 | 17篇 |
机械仪表 | 10篇 |
建筑科学 | 9篇 |
能源动力 | 13篇 |
轻工业 | 15篇 |
水利工程 | 1篇 |
无线电 | 54篇 |
一般工业技术 | 61篇 |
冶金工业 | 36篇 |
原子能技术 | 2篇 |
自动化技术 | 49篇 |
出版年
2022年 | 3篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 15篇 |
2012年 | 8篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 21篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
81.
In a recent article [J. Rajagopalan, J.H. Han, M.T.A. Saif, Science 315 (2007) 1831–1834], we have reported substantial (50–100%) plastic strain recovery in freestanding nanocrystalline metal films (grain size 50–65 nm) after unloading. The strain recovery was time dependent and thermally activated. Here we model the time evolution of this strain recovery in terms of a thermally activated dislocation propagation mechanism. The model predicts an activation volume of ≈42b3 for the strain recovery process in aluminum. 相似文献
82.
Prasanna J.K. Rajagopalan A.N. 《Vision, Image and Signal Processing, IEE Proceedings -》2006,153(5):650-656
A recursive-state estimation scheme for image restoration using the particle filter is described. Handling non-causal blurs within a recursive framework is a challenging problem. Most recursive image restoration schemes assume the blur to be causal or semi-causal in nature, but this is unrealistic. A novel choice for the state vector and a concurrent block estimation technique to incorporate full-plane regions of support for the image model as well as the blur are proposed. The particle filter-based framework enables general types of degradations to be tackled. The method assumes that the functional form of the distortion as well as the noise statistics are known but does not place any restrictions on them. Several experimental results are presented to validate the approach 相似文献
83.
We report a calculation of the band structure and superconductivity of phosphorus in the simple cubic phase under pressure. The effect of pressure on the band structure is obtained by means of the linear muffin-tin orbital method. The superconducting transition temperature(T
c) is calculated using the Allen-Dynes formula. It is found that the value ofT
c increases continuously with pressure from 110 kbar up to 210 kbar and then decreases. The change in the slope ofT
c is associated with the appearance of a new piece of Fermi surface. The calculated values ofT
c are compared with the available experimental data. 相似文献
84.
Flexible versus dedicated technology: A capacity expansion model 总被引:3,自引:0,他引:3
S. Rajagopalan 《International Journal of Flexible Manufacturing Systems》1993,5(2):129-142
Over the past two decades, flexible manufacturing systems have been adopted in a variety of industries. Shorter product lives have necessitated acquiring flexible facilities. Further, the economies of scope that can be derived from producing products with different seasonality have made flexible facilities attractive. At the same time, dedicated facilities (such as transfer lines) have not disappeared because they offer economies of scale beneficial in high volume manufacturing environments. Hence, when producing a wide variety of products with different seasonality and demand growth rates, firms need to consider both economies of scale and economies of scope in deciding whether to acquire capacity of flexible or dedicated technology or both. In this paper, we consider the problem of making capacity acquisition decisions, when there is a choice of flexible and dedicated technologies available in a deterministic multi-product manufacturing environment with demand assumed to be nondeclining over time. We present a novel formulation of the problem and show the equivalence of the formulation to the uncapacitated plant location formulation. This enables us to use a very efficient solution procedure (Erlenkotter 1978) to solve even large problems optimally. We then present the results of an extensive computational study performed to evaluate the impact of key problem parameters on the proportion of flexible and dedicated capacity acquired. An interesting result of the study is that the proportion of flexible capacity acquired decreases with increasing scale economies. We also find that investment in flexible technology is significant even when it is relatively more expensive than dedicated technology. 相似文献
85.
G. Rajagopalan N. S. Reddy H. Ehsani I. B. Bhat P. S. Dutta R. J. Gutmann G. Nichols O. Sulima 《Journal of Electronic Materials》2003,32(11):1317-1321
A single-step diffusion followed by precise etching of the diffused layer has been developed to obtain a diffusion profile
appropriate for high-efficiency GaSb thermophotovoltaic (TPV) cells. The junction depth was controlled through monitoring
of light current-voltage (I–V) curves (photovoltaic response) during the post-diffusion emitter-etching process. The measured
photoresponses (prior to device fabrication) have been correlated with the quantum efficiencies (QEs) and the open-circuit
voltages in the fabricated devices. An optimum junction depth for obtaining the highest QE and open-circuit voltage is presented
based on diffusion lengths (or minority carrier lifetimes), carrier mobility, and the typical diffused impurity profile in
GaSb. 相似文献
86.
87.
R Rajagopalan RT Anderson S Sarma J Kallal C Retchin J Jones JF Fowler EF Sherertz 《Canadian Metallurgical Quarterly》1998,9(3):149-154
AIM: To investigate the value of RNA detection by nucleic acid sequence based amplification (NASBA) for the monitoring of Chlamydia trachomatis infections after antibiotic treatment. METHODS: Cervical smears (n = 97) and urine specimens (n = 61) from 25 C trachomatis positive female patients were analysed for the presence of C trachomatis 16S ribosomal RNA (rRNA) by NASBA and C trachomatis plasmid DNA by the polymerase chain reaction (PCR) before and up to five weeks after antibiotic treatment. RESULTS: Chlamydia trachomatis RNA was found in all cervical smears taken before antibiotic treatment (n = 24) and in two smears taken one week after antibiotic treatment; no C trachomatis RNA was detected after two weeks or more. In contrast, C trachomatis DNA was found in all such specimens before treatment, and 21 of 25, six of 21, and five of 20 smears were found to be positive at one, two, and three weeks after treatment, respectively. After four weeks, only one of six smears was positive, and this smear had been negative in the two preceding weeks. Of the 61 urine samples investigated, C trachomatis DNA and C trachomatis RNA were found in all before treatment (n = 15), whereas one week after treatment four of 15 were C trachomatis DNA positive and C trachomatis RNA was detected in one sample only. CONCLUSIONS: These data show that RNA detection by NASBA can be used successfully to monitor C trachomatis infections after antibiotic treatment. Furthermore, it might be possible to use urine specimens as a test of cure because neither C. trachomatis DNA or RNA could be detected two weeks or more after treatment. 相似文献
88.
S Pulimood B Rajagopalan M Jacob S George I Korah 《Canadian Metallurgical Quarterly》1997,22(6):295-296
Hypomelanosis of Ito (HOI) is a neurocutaneous disorder which clinically is a well-characterised disease, in which chromosomal instability may be a component. Various neurological and other non-cutaneous malformations have been reported in association with the characteristic swirling pattern of hypopigmentation. We report two cases of this rare condition, one with hitherto unreported associations. 相似文献
89.
AE Chucrallah MK Crow LE Rice S Rajagopalan SD Hudnall 《Canadian Metallurgical Quarterly》1994,25(5):541-545
Published reports of posttransplant myeloma are extremely uncommon (three cases); to the best of our knowledge there have been no reported cases in cardiac transplant recipients. We are also unaware of any report of Epstein-Barr virus (EBV) genome studies in posttransplant myeloma. We report here the case of a 48-year-old man who developed multiple myeloma 1.5 years after cardiac transplantation. The results of a serum analysis were consistent with past EBV infection. Biopsy of a skull lesion showed a monomorphous population of malignant immature plasma cells that showed monotypic cytoplasmic staining with antibodies to lambda light chains. A monoclonal immunoglobulin heavy chain gene rearrangement was detected by polymerase chain reaction (PCR). Both EBER-1 in situ hybridization and EBNA-1 PCR were negative for the EBV genome. Cyclosporin withdrawal was followed by transient clinical and biological improvement, but the tumor later progressed and eventually stabilized in response to treatment with dexamethasone alone. This case illustrates that posttransplant lymphoproliferative disorders (PTLPDs) encompass not only EBV-positive but also EBV-negative cases and not only lymphomas but also myelomas. 相似文献
90.
Ranjusha Rajagopalan Yougen Tang Xiaobo Ji Chuankun Jia Haiyan Wang 《Advanced functional materials》2020,30(12)
Demand for energy in day to day life is increasing exponentially. However, existing energy storage technologies like lithium ion batteries cannot stand alone to fulfill future needs. In this regard, potassium ion batteries (KIBs) that utilize K ions in their charge storage mechanism have attracted considerable attention due to their unique properties and are therefore established as one of the future battery systems of interest among the scientific community. Nevertheless, the development and identification of appropriate electrode materials is very essential for practical applications. This review features the current development in KIBs electrode and electrolyte materials, the present challenges facing this technology (in the commercial aspect), and future aspects to develop fully functional KIBs. The potassium storage mechanisms, evolution of the KIBs, and the advantages and disadvantages of each category of materials are included. Additionally, various approaches to enhance the electrochemical performances of KIBs are also discussed. This review is not only an amalgamation of different viewpoints in literature, but also contains concise perspectives and strategies. Moreover, the potential emergence of a novel class of K‐based dual ion batteries is also analyzed for the first time. 相似文献