全文获取类型
收费全文 | 399篇 |
免费 | 11篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 113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 | 19篇 |
水利工程 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 63篇 |
冶金工业 | 38篇 |
原子能技术 | 2篇 |
自动化技术 | 55篇 |
出版年
2022年 | 5篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 9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410条查询结果,搜索用时 0 毫秒
1.
V Douzdjian SS Bhaskar PK Baliga KK Gugliuzza PR Rajagopalan 《Canadian Metallurgical Quarterly》1997,20(8):1310-1314
OBJECTIVE: The racial impact on graft outcome is not well defined in diabetic recipients. The purpose of this study is to analyze our experience with kidney-alone (A) and kidney-pancreas (KP) transplantation in type 1 diabetic recipients and evaluate the impact of racial disparity on outcome. RESEARCH DESIGN AND METHODS: The records of 217 kidney transplants (118 KA, 99 KP) performed on type 1 diabetic patients between 1985 and 1995 at the Medical University of South Carolina and the University of Texas Medical Branch were reviewed. RESULTS: A total of 53 (31%) white patients and 15 (33%) black patients experienced at least one episode of biopsy-proven acute rejection of the renal graft (NS). Patient survival at 1, 2, and 5 years was similar in white (92, 87, 69%) and black (91, 91, 69%) patients (NS). Kidney graft survival at 1, 2, and 5 years in the KA group was 72, 62, and 42% in blacks, compared with 79, 76, and 53% in whites (NS). Kidney graft survival at 1, 2, and 5 years in the KP group was 92, 92, and 74% in blacks, compared with 83, 77, and 58% in whites (NS). Pancreas graft survival at 1, 2, and 5 years was 81, 81, and 81% in blacks, compared with 81, 75, and 62% in whites (NS). Cox regression analysis revealed that donor age > or = 40 years increased the risk of renal graft failure 6.2-fold (P = 0.0001), whereas the addition of a pancreas transplant to a kidney and a living-related transplant decreased the risk of failure of the kidney graft 0.2 (P = 0.005) and 0.1 times (P = 0.005). CONCLUSIONS: Our results suggest that when compared with whites, there may be a trend toward an improved kidney and pancreas graft outcome in blacks undergoing KP transplants. These findings suggest that diabetes may override the risk factors that account for the pronounced disparity in outcome observed between nondiabetic white and black recipients. 相似文献
2.
A simple method (based on Floquet theory) for obtaining the characteristic equation (and hence stability) of periodic discrete-time systems is presented. Using this method it is shown that 2-periodic controllers can be used to relocate the zeros of SISO plants. Some examples are considered to illustrate the use of 2-periodic controllers for robust control of finite gain margin problems 相似文献
3.
M. Rajagopalan R. Asokamani N. Vasavi G. Subramoniam 《Journal of Low Temperature Physics》1987,66(3-4):169-172
Recent experimental observations show that metallic lithium becomes a superconductor at high pressure. Here the theoretically calculated band structure as well as the superconducting transition temperature for this metal at 247 kbar pressure are reported. The band structure was obtained using the APW method. The superconducting transition temperature determined using the band structure results agrees fairly well with that measured experimentally. 相似文献
4.
KI Priyadarsini MA Naylor MR Stratford P Wardman 《Canadian Metallurgical Quarterly》1996,25(2):99-107
This study defines the current modes of treatment of patients with uterine fibromas with a review of the literature. Progesterone treatments appear to be principally used in cases of minor functional symptomatology and we discuss recent studies of mifepristone. GnRH agonists are particularly effective in preoperative treatment for conservative surgery. The indications and results of hysteroscopic resection and laparoscopic myomectomy are compared to those of classic myomectomy and hysterectomy. The indications for myolysis are discussed. 相似文献
5.
Motion blur due to camera shake is a common occurrence. During image capture, the apparent motion of a scene point in the image plane varies according to both camera motion and scene structure. Our objective is to infer the camera motion and the depth map of static scenes using motion blur as a cue. To this end, we use an unblurred–blurred image pair. Initially, we develop a technique to estimate the transformation spread function (TSF) which symbolizes the camera shake. This technique uses blur kernels estimated at different points across the image. Based on the estimated TSF, we recover the complete depth map of the scene within a regularization framework. 相似文献
6.
Emergency medical service (EMS) providers continually seek ways to improve system performance particularly the response time to incidents. The demand for ambulances fluctuate throughout the week, depending on the day of week, and even the time of day, therefore EMS operators can improve system performance by dynamic relocation/redeployment of ambulances in response to fluctuating demand patters. The objective of the model is to determine the minimum number of ambulances and their locations for each time cluster in which significant changes in demand pattern occur while meeting coverage requirement with a predetermined reliability. The model is further enhanced by calculating ambulance specific busy probabilities and validated by a comprehensive simulation model. Computational results on experimental data sets and data from an EMS agency are provided. 相似文献
7.
Soumya Priyadarsini Panda Ajit Kumar Nayak 《International Journal of Speech Technology》2017,20(4):959-976
Designing text-to-speech systems capable of producing natural sounding speech segments in different Indian languages is a challenging and ongoing problem. Due to the large number of possible pronunciations in different Indian languages, a number of speech segments are needed to be stored in the speech database while a concatenative speech synthesis technique is used to achieve highly natural speech segments. However, the large speech database size makes it unusable for small hand held devices or human computer interactive systems with limited storage resources. In this paper, we proposed a fraction-based waveform concatenation technique to produce intelligible speech segments from a small footprint speech database. The results of all the experiments performed shows the effectiveness of the proposed technique in producing intelligible speech segments in different Indian languages even with very less storage and computation overhead compared to the existing syllable-based technique. 相似文献
8.
S R Rajagopalan 《Bulletin of Materials Science》1983,5(3-4):317-322
The lowest concentration that can be estimated with 100% error in chemical analysis by instrumental technique is referred
to as detection limit. It is equal to the ratio of twice the background signal to the magnitude of analytical signal corresponding
to a concentration of unity. Detection limit (dl) could be improved if the analytical signal alone could be selectively amplified without affecting the background. It is
shown that this could be achieved by chemical amplification. Atomic amplification of two or three orders of magnitude could
be obtained by combining two chemical amplifications in series. It is demonstrated that by using heteropoly acid formation
as the first amplification reaction and determining molybdenum in the heteropoly acid by catalyticdc polarographic wave, a detection limit for the hetero atom of less than a ppb can be obtained. It is pointed out that the
approach of selectively amplifying analytical signals by tandem chemical amplification reactions makes it possible to perform
ultratrace analysis (ppb level) with classical instrumental analytical techniques which havedl at ppm level. 相似文献
9.
Venkatesh Rajagopalan Author Vitae Author Vitae Rohan Samsi Jeffrey Mayer 《Pattern recognition》2007,40(11):2897-2907
This paper presents symbolic time series analysis (STSA) of multi-dimensional measurement data for pattern identification in dynamical systems. The proposed methodology is built upon concepts derived from Information Theory and Automata Theory. The objective is not merely to classify the time series patterns but also to identify the variations therein. To achieve this goal, a symbol alphabet is constructed from raw data through partitioning of the data space. The maximum entropy method of partitioning is extended to multi-dimensional space. The resulting symbol sequences, generated from time series data, are used to model the dynamical information as finite state automata and the patterns are represented by the stationary state probability distributions. A novel procedure for determining the structure of the finite state automata, based on entropy rate, is introduced. The diversity among the observed patterns is quantified by a suitable measure. The efficacy of the STSA technique for pattern identification is demonstrated via laboratory experimentation on nonlinear systems. 相似文献
10.
Graph structure in the Web 总被引:11,自引:0,他引:11
Andrei Broder Ravi Kumar Farzin Maghoul Prabhakar Raghavan Sridhar Rajagopalan Raymie Stata Andrew Tomkins Janet Wiener 《Computer Networks》2000,33(1-6)
The study of the Web as a graph is not only fascinating in its own right, but also yields valuable insight into Web algorithms for crawling, searching and community discovery, and the sociological phenomena which characterize its evolution. We report on experiments on local and global properties of the Web graph using two AltaVista crawls each with over 200 million pages and 1.5 billion links. Our study indicates that the macroscopic structure of the Web is considerably more intricate than suggested by earlier experiments on a smaller scale. 相似文献