全文获取类型
收费全文 | 2538篇 |
免费 | 79篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 32篇 |
综合类 | 4篇 |
化学工业 | 625篇 |
金属工艺 | 80篇 |
机械仪表 | 62篇 |
建筑科学 | 45篇 |
能源动力 | 103篇 |
轻工业 | 76篇 |
水利工程 | 19篇 |
石油天然气 | 2篇 |
无线电 | 503篇 |
一般工业技术 | 408篇 |
冶金工业 | 262篇 |
原子能技术 | 21篇 |
自动化技术 | 380篇 |
出版年
2023年 | 8篇 |
2022年 | 37篇 |
2021年 | 48篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 41篇 |
2017年 | 34篇 |
2016年 | 47篇 |
2015年 | 42篇 |
2014年 | 83篇 |
2013年 | 206篇 |
2012年 | 134篇 |
2011年 | 149篇 |
2010年 | 136篇 |
2009年 | 153篇 |
2008年 | 148篇 |
2007年 | 112篇 |
2006年 | 107篇 |
2005年 | 91篇 |
2004年 | 82篇 |
2003年 | 72篇 |
2002年 | 67篇 |
2001年 | 50篇 |
2000年 | 48篇 |
1999年 | 51篇 |
1998年 | 105篇 |
1997年 | 67篇 |
1996年 | 56篇 |
1995年 | 38篇 |
1994年 | 38篇 |
1993年 | 29篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 26篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1973年 | 8篇 |
1967年 | 5篇 |
排序方式: 共有2622条查询结果,搜索用时 15 毫秒
1.
The accumulation of two independent, broadly applicable formulations for determining the boundary to manipulator workspaces, presented elsewhere, are compared in this paper. Insights gained from one method are used to explain behavior exhibited in the other. Results are also compared and validated. A numerical formulation based on continuation methods is used to map curves that are on the boundary of a manipulator workspace. Analytical criteria based on row rank deficiency criteria of the manipulator's analytical Jacobian are used to map a family of one-dimensional solution curves on the boundary. The other formulation, based on a similar rank-deficiency criteria, yields analytic boundaries parametrized in terms of surface patches on the boundary. Results concerning the applicability of the numerical method to open- and closed-loop systems are compared with those limited to the open-loop for the analytical method. Conclusions regarding the behavior of the manipulator on geometric entities characterized by singular curves, higher-order bifurcation points, and surfaces inside the workspace are drawn. Applicability of both methods and their limitations are also addressed. 相似文献
2.
Shen-Fu Hsiao Jia-Siang Yeh 《Electronics letters》1998,34(12):1180-1182
A pass-transistor based cell library containing only two types of cells is designed and a corresponding logic/circuit synthesiser developed for logic mapping of any combinational circuit. The proposed design has better performance than the recently proposed lean integration with pass transistors (LEAP) cell library. Furthermore, the modified LEAP cell library can be easily migrated to a new process technology due to the smaller number of cells 相似文献
3.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
4.
This study focuses on how to assess the optimal environmental investment decisions under economic and ecological uncertainty, and establishes the continuous time model using the real option approach to optimize environmental pollution policy. Unlike traditional cost benefit analysis, this work extends the model of [Pindyck, R.S., 2002. Optimal timing problems in environmental economics. Journal of Economic Dynamics and Control 26(9–10), 1677–1697], and attempts to identify the storage threshold of pollution stocks and the optimal timing for implementing environmental pollution decisions. 相似文献
5.
Lianshan Yan Yeh C. Yang G. Lin L. Chen Z. Shi Y.Q. Willner A.E. Yao X.S. 《Lightwave Technology, Journal of》2003,21(7):1676-1684
We demonstrate the first programmable group-delay module based on polarization switching. With a unique binary tuning mechanism, the device can generate any differential group delay value from -45 to +45 ps with a resolution of 1.40 ps, or any true-time-delay value from 0 to 45 ps with a resolution of 0.7 ps. The delay varying speeds for both applications are under 1 ms and can be as fast as 0.1 ms. We evaluate both the dynamic and static performances of the device while paying special attention to its dynamic figures of merit for polarization-mode dispersion emulation and compensation applications. Our experiment shows that the device exhibits a negligible transient-effect induced power penalty (<0.2 dB) in a 10-Gb/s nonreturn-to-zero system. 相似文献
6.
Ho-Ming Yeh 《Chemical Engineering Communications》2002,189(10):1360-1367
Effects of inclined angle and plate spacing on the degree of separation in batch-type flat-plate thermal diffusion columns, with operating expense and fixed charge kept unchanged, are discussed. It was found that the degree ofseparation increases when the inclined angle increases or when the platespacing decreases. However, decreasing the plate spacing will lead to decreasingthe amount of solution to be treated in the column, while increasing the inclined angle will enlarge the operating time for reaching the steady state. 相似文献
7.
MT Yeh TN Mather RT Coughlin C Gingrich-Baker JW Sumner RF Massung 《Canadian Metallurgical Quarterly》1997,35(4):944-947
A new indirect fluorescent-antibody (IFA) assay with antigen produced in vitro in the human promyelocytic leukemia cell line HL60 was used to identify the first recognized case of human granulocytic ehrlichiosis in Rhode Island. This IFA assay was used to detect granulocytic ehrlichiae in white-footed mice and in a dog inhabiting the area surrounding the patient's residence. Host-seeking Ixodes scapularis ticks found in the same habitat also were infected. I. scapularis ticks collected from other locations were fed on dogs and New Zealand White rabbits to assess the competency of these species as hosts of granulocytotropic Ehrlichia. Tick-induced infections of dogs were confirmed by serologic testing, tissue culture isolation, and PCR amplification, whereas several rabbits seroconverted but were PCR and culture negative. PCR amplification of the 16S rRNA gene and DNA sequencing of the PCR products or culture isolation was used to confirm granulocytic Ehrlichia infections in humans, dogs, white-footed mice, and ticks. 相似文献
8.
The behavior of a spatially smoothing adaptive array is examined. An expression for the weight vector is first derived. Using the array gain on the desired signal and the coherent interference is obtained. Then the expression for output signal-to-noise (SNR) is derived. It shows that the performance of the spatially smoothing array depends on the number of the subarrays, the angle separation, relative power and initial phase difference between the desired signal and the coherent interference. For good interference suppression it is found that the magnitude of the phase difference of the incident and interference signals must be greater than the beamwidths of both the subarray and the equivalent array. There is also a tradeoff between increasing the groups of subarrays and decreasing the number of elements in the subarrays. Computer simulation results are given that validate the analysis 相似文献
9.
Herchang Ay JiinYuh JangJer-Nan Yeh 《International Journal of Heat and Mass Transfer》2002,45(20):4069-4078
An experimental study is performed using an infrared thermovision to monitor temperature distribution over a plate-fin surface inside the plate finned-tube heat exchangers. The differentiation of the temperature function is derived to determine the local convective heat transfer coefficients on the tested fin, using a local element lumped conduction equation included the convective effect on the boundaries with experimental data. It is disclosed that the infrared thermography is capable of rapidly detecting location and extent of transition and separation regions of the boundary layer over the whole surface of the tested models. Through the comparison of the test results on the strategy region of the in-line and staggered arrangements, it is more easy to understand or interpret the detailed dynamic phenomena of flow existed in the heat exchangers. In addition, the experimental results demonstrate that the averaged heat transfer coefficient of staggered configuration is 14-32% higher than that of in-lined configuration 相似文献
10.