全文获取类型
收费全文 | 20383篇 |
免费 | 870篇 |
国内免费 | 145篇 |
专业分类
电工技术 | 328篇 |
综合类 | 33篇 |
化学工业 | 4822篇 |
金属工艺 | 602篇 |
机械仪表 | 646篇 |
建筑科学 | 385篇 |
矿业工程 | 48篇 |
能源动力 | 1429篇 |
轻工业 | 1279篇 |
水利工程 | 157篇 |
石油天然气 | 87篇 |
武器工业 | 1篇 |
无线电 | 2440篇 |
一般工业技术 | 4554篇 |
冶金工业 | 1463篇 |
原子能技术 | 177篇 |
自动化技术 | 2947篇 |
出版年
2024年 | 103篇 |
2023年 | 434篇 |
2022年 | 1038篇 |
2021年 | 1198篇 |
2020年 | 943篇 |
2019年 | 984篇 |
2018年 | 1257篇 |
2017年 | 1000篇 |
2016年 | 955篇 |
2015年 | 626篇 |
2014年 | 906篇 |
2013年 | 1758篇 |
2012年 | 944篇 |
2011年 | 1127篇 |
2010年 | 911篇 |
2009年 | 857篇 |
2008年 | 768篇 |
2007年 | 619篇 |
2006年 | 524篇 |
2005年 | 400篇 |
2004年 | 292篇 |
2003年 | 270篇 |
2002年 | 207篇 |
2001年 | 193篇 |
2000年 | 188篇 |
1999年 | 184篇 |
1998年 | 311篇 |
1997年 | 248篇 |
1996年 | 234篇 |
1995年 | 181篇 |
1994年 | 172篇 |
1993年 | 161篇 |
1992年 | 118篇 |
1991年 | 141篇 |
1990年 | 109篇 |
1989年 | 114篇 |
1988年 | 88篇 |
1987年 | 94篇 |
1986年 | 79篇 |
1985年 | 91篇 |
1984年 | 77篇 |
1983年 | 79篇 |
1982年 | 68篇 |
1981年 | 74篇 |
1980年 | 50篇 |
1979年 | 37篇 |
1978年 | 33篇 |
1977年 | 28篇 |
1976年 | 38篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
61.
Journal of Communications Technology and Electronics - A Compact U-shaped multiple-inputs and multiple-output (MIMO)-antenna with dimensions of 23 × 47 mm2 has been proposed for... 相似文献
62.
The present article is concerned with the investigation of disturbances in a homogeneous transversely isotropic thermoelastic rotating medium with two temperatures, in the presence of the combined effects of Hall currents and magnetic field. The formulation is applied to the thermoelasticity theories developed by Green-Naghdi theories of type-II and type-III. Laplace and Fourier transform techniques are applied to solve the problem. The analytical expressions of displacements, stress components, temperature change, and current density components are obtained in the transformed domain. A numerical inversion technique has been applied to obtain the results in the physical domain. Numerical simulated results are depicted graphically to show the effect of Hall current and two temperatures on resulting quantities. Some special cases are also deduced from the present investigation. 相似文献
63.
Sanjay Sahare Ravi Kant Choubey Gurunath Jadhav Tejashree M. Bhave Samrat Mukherjee Sunil Kumar 《Journal of Superconductivity and Novel Magnetism》2017,30(6):1439-1446
In this report, we studied various structural and optical properties of pure and copper-doped cadmium oxide (CdO) thin films. Nanostructured Cu-doped CdO films were deposited using sol–gel spin-coating technique. The structural and morphological changes have been observed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM) studies. The optical and electrical properties of the pure and Cu-doped CdO thin films were studied by UV–vis spectroscopy and four-point probe method, respectively. The XRD peaks show the formation of nanocrystalline CdO with cubic face-centered crystal structure. The band gaps of the as deposited films were found in the range of 2.32–2.73 eV, while after doping, it decreases due to structural deformation. The electrical resitivity was found to decrease approximately ~10 in Cu-doped CdO thin films. 相似文献
64.
Microfluidics: Inertial Microfluidic Cell Stretcher (iMCS): Fully Automated,High‐Throughput,and Near Real‐Time Cell Mechanotyping (Small 28/2017) 下载免费PDF全文
65.
66.
Ravi Shanker Vidyarthy Dheerendra Kumar Dwivedi Vasudevan Muthukumaran 《Materials and Manufacturing Processes》2018,33(7):709-717
In the present work, the influence of process parameters such as welding current (I), welding speed (S), and flux coating density (F) on different aspects of weld bead geometry for example depth of penetration (DOP), bead width (BW), depth to width ratio (D/W), and weld fusion zone area (WA) were investigated by using the central composite design (CCD). 9–12% Cr ferritic stainless steel (FSS) plates were welded using A-TIG welding. It was observed that all input variables have a direct influence on the DOP, BW, and D/W. However, flux coating density has no significant effect on WA. Mathematical models were generated from the obtained responses to predict the weld bead geometry. An optimized DOP, BW, D/W, and WA of 6.95?mm, 8.76?mm, 0.80, and 41.99?mm2, respectively, were predicted at the welding current of 213.78 A, the welding speed of 96.22?mm/min, and the flux coating density of 1.99?mg/cm2. Conformity test was done to check the practicability of the developed models. The conformity test results were in good agreement with the predicted values. Arc constriction and reversal in Marangoni convection were considered as major mechanisms for the deep and narrow weld bead during A-TIG welding. 相似文献
67.
68.
69.
Rajnish Kumar Rai 《Information & Communications Technology Law》2010,19(2):115-146
The amendment of patent law of India in 2005 to fulfill her international obligation under the TRIPS Agreement (World Trade Organization Agreement on Trade Related Intellectual Property Rights) was an outcome of an attempt to balance the competing interests of several stakeholders, including indigenous pharmaceutical companies, multi-national pharmaceutical companies, non-governmental organizations and civil society groups concerned with access to affordable drugs. The adverse consequence of this delicate balancing is introduction of some provisions in the Act whose compatibility with the TRIPS Agreement is questionable, and which therefore are prone to litigations. Section 107A(b) of the amended patent law dealing with parallel imports is one such provision, which, if interpreted word for word could have significant connotations for the rights of a patent owner. This article aims to examine the inconsistencies intrinsic in Section 107A(b) and discusses the divergences in the Indian patent law associated with the doctrine of exhaustion and parallel imports. This article also proposes legal amendments with a view to eliminate inconsistencies intrinsic in the section and enlarge the ambit of the exhaustion principle conceptualized therein, while concurrently remaining compliant with the TRIPS Agreement. 相似文献
70.
This paper considers an economic lot sizing model with constant capacity, non-increasing setup cost, and convex inventory cost function. Algorithms with computational time of O(N×TDN)have been developed for solving the model, where N is the number of planning periods and TDN is the total demand. This study partially characterizes the optimal planning structure of the model. A new efficient algorithm with computational time of O(N log N) has also been developed based on the partial optimal structure. Moreover, computational study demonstrates that the new algorithm is efficient. 相似文献