全文获取类型
收费全文 | 7055篇 |
免费 | 162篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 265篇 |
综合类 | 9篇 |
化学工业 | 1526篇 |
金属工艺 | 198篇 |
机械仪表 | 129篇 |
建筑科学 | 239篇 |
矿业工程 | 11篇 |
能源动力 | 285篇 |
轻工业 | 676篇 |
水利工程 | 34篇 |
石油天然气 | 13篇 |
无线电 | 533篇 |
一般工业技术 | 1083篇 |
冶金工业 | 1375篇 |
原子能技术 | 191篇 |
自动化技术 | 668篇 |
出版年
2022年 | 66篇 |
2021年 | 87篇 |
2020年 | 53篇 |
2019年 | 86篇 |
2018年 | 95篇 |
2017年 | 90篇 |
2016年 | 112篇 |
2015年 | 80篇 |
2014年 | 155篇 |
2013年 | 341篇 |
2012年 | 235篇 |
2011年 | 342篇 |
2010年 | 261篇 |
2009年 | 270篇 |
2008年 | 282篇 |
2007年 | 273篇 |
2006年 | 249篇 |
2005年 | 254篇 |
2004年 | 191篇 |
2003年 | 204篇 |
2002年 | 201篇 |
2001年 | 123篇 |
2000年 | 124篇 |
1999年 | 142篇 |
1998年 | 317篇 |
1997年 | 241篇 |
1996年 | 175篇 |
1995年 | 154篇 |
1994年 | 170篇 |
1993年 | 132篇 |
1992年 | 85篇 |
1991年 | 83篇 |
1990年 | 87篇 |
1989年 | 79篇 |
1988年 | 71篇 |
1987年 | 68篇 |
1986年 | 78篇 |
1985年 | 91篇 |
1984年 | 88篇 |
1983年 | 76篇 |
1982年 | 79篇 |
1981年 | 86篇 |
1980年 | 76篇 |
1979年 | 57篇 |
1978年 | 40篇 |
1977年 | 79篇 |
1976年 | 101篇 |
1975年 | 68篇 |
1973年 | 47篇 |
1972年 | 46篇 |
排序方式: 共有7235条查询结果,搜索用时 0 毫秒
71.
Arne Ketil Eidsvik Randi Karlsen Gordon Blair Paul Grace 《Journal of Computer and System Sciences》2008,74(2):158-169
Transaction execution in mobile environments needs to be flexible, not only to support typical mobile computing characteristics, like movement, disconnections and limited resources, but also to support the variety of transactional properties that might be required by different applications. Existing models for mobile transaction management solve different aspects of transaction execution, but are not flexible enough to solve all required aspects. Instead of designing a new transaction model, we propose a middleware (MobileTSe) which utilize existing transaction models to handle various requirements for mobile transaction execution. This paper presents an approach for flexible transaction processing in mobile applications, and describes how MobileTSe makes transaction services with different properties available on mobile units. We suggest a solution with transaction service discovery and control using UPnP. 相似文献
72.
Oliver Bimber Daisuke Iwai Gordon Wetzstein Anselm Grundhöfer 《Computer Graphics Forum》2008,27(8):2219-2245
This article focuses on real‐time image correction techniques that enable projector‐camera systems to display images onto screens that are not optimized for projections, such as geometrically complex, coloured and textured surfaces. It reviews hardware‐accelerated methods like pixel‐precise geometric warping, radiometric compensation, multi‐focal projection and the correction of general light modulation effects. Online and offline calibration as well as invisible coding methods are explained. Novel attempts in super‐resolution, high‐dynamic range and high‐speed projection are discussed. These techniques open a variety of new applications for projection displays. Some of them will also be presented in this report. 相似文献
73.
Electron tomography (ET) combines electron microscopy and the principles of tomographic imaging in order to reconstruct the three-dimensional structure of complex biological specimens at molecular resolution. Weighted back-projection (WBP) has long been the method of choice since the reconstructions are very fast. It is well known that iterative methods produce better images, but at a very costly time penalty. In this work, it is shown that efficient parallel implementations of iterative methods, based primarily on data decomposition, can speed up such methods to an extent that they become viable alternatives to WBP. Precomputation of the coefficient matrix has also turned out to be important to substantially improve the performance regardless of the number of processors used. Matrix precomputation has made it possible to speed up the block-iterative component averaging (BICAV) algorithm, which has been studied before in the context of computerized tomography (CT) and ET, by a factor of more than 3.7. Component-averaged row projections (CARP) is a recently introduced block-parallel algorithm, which was shown to be a robust method for solving sparse systems arising from partial differential equations. It is shown that this algorithm is also suitable for single-axis ET, and is advantageous over BICAV both in terms of runtime and image quality. The experiments were carried out on several datasets of ET of various sizes, using the blob model for representing the reconstructed object. 相似文献
74.
Yoshihisa Shinya Kenji Kamiya Tomoyuki Toyoda Yasumi Endo Nelly Soudakova Hirofumi Kondo 《Journal of the Society for Information Display》2009,17(4):331-336
Abstract— The display used in current cell phones has an air gap between the cover glass and the liquid‐crystal‐display (LCD) module to prevent the LCD glass from being damaged. Reflections at the boundaries of the air gap cause a reduction in the LCD luminance and contrast. To address this problem, a newly proposed LCD structure has been investigated. The “Super View Resin (SVR),” a transparent elastic resin which improves the shock resistance and visibility of the LCD, has been developed. Filling the air gap between the cover glass and LCD module with a refractive‐index‐matching resin solves the light‐reflection problem inherent in the use of a reinforced cover‐glass lens. Moreover, the elastic filler works as a damper, reducing any external shock, which prevents not only the cover glass and LCD module from being damaged, but also the glass from being shattered when it is broken. 相似文献
75.
Ken-ichi Kumagai Kenji Kawano Isao Watanabe Kusuo Nishiyama Kanetada Nagamine 《Journal of Superconductivity》1994,7(1):63-67
Muon spin rotation (
+SR) measurement provides clear evidence of the antiferromagnetic order of Cu moments below 35 K for La2–x
Ba
x
CuO4 and below 15 K for La2–x
Sr
x
CuO4 in the narrow range ofx where the high-T
c
superconductivity (SC) is suppressed remarkably. The results suggest that the change of the electronic state coupled with the lattice instability is relevant to the local suppression of SC and freezing of spin fluctuations of the Cu moment. 相似文献
76.
Generalized nonimaging compound elliptical luminaires (CEL's) and compound hyperbolic luminaires (CHL's) are developed for pair-overlap illumination applications. A comprehensive analysis of CEL's and CHL's is presented. This includes the possibility of reflector truncation, as well as the extreme direction that spans the full range from positive to negative. Negative extreme direction devices have been overlooked in earlier studies and are shown to be well suited to illumination problems for which large cutoff angles are required. Flux maps can be calculated analytically without the need for computer ray tracing. It is demonstrated that, for a broad range of cutoff angles, adjacent pairs of CEL's and CHL's can generate highly uniform far-field illuminance while maintaining maximal lighting efficiency and excellent glare control. The trade-off between luminaire compactness and flux homogeneity is also illustrated. For V troughs, being a special case of CHL's and being well suited to simple, inexpensive fabri ation, we identify geometries that closely approach the performance characteristics of the optimized CEL's and CHL's. 相似文献
77.
78.
Computational Economics - This study tries to unravel the stock market prediction puzzle using the textual analytic with the help of natural language processing (NLP) techniques and Deep-learning... 相似文献
79.
80.
S Rustaeus P Stillemark K Lindberg D Gordon SO Olofsson 《Canadian Metallurgical Quarterly》1998,273(9):5196-5203
In cells in which the lipoprotein assembly process had been inactivated by brefeldin A (BFA), membrane-associated apoB-100 disappeared without forming lipoproteins or being secreted, indicating that it was degraded. Reactivation of the assembly process by chasing the cells in the absence of BFA, gave rise to a quantitative recovery of the membrane-associated apoB-100 in the very low density lipoprotein (VLDL) fraction in the medium. These results indicate that the membrane-associated apoB-100 can be converted to VLDL. A new method was developed by which the major amount (88%) of microsomal apoB-100 but not integral membrane proteins could be extracted. The major effect of this method was to increase the recovery of apoB-100 that banded in the LDL and HDL density regions, suggesting that the membrane-associated form of apoB-100 is partially lipidated. We also investigated the role of the microsomal triglyceride transfer protein (MTP) in the assembly of apoB-100 VLDL using a photoactivatable MTP inhibitor (BMS-192951). This compound strongly inhibited the assembly and secretion of apoB-100 VLDL when present during the translation of the protein. To investigate the importance of MTP during the later stages in the assembly process, the cells were preincubated with BFA (to reversibly inhibit the assembly of apoB-100 VLDL) and pulse-labeled (+BFA) and chased (+BFA) for 30 min to obtain full-length apoB-100 associated with the microsomal membrane. Inhibition of MTP after the 30-min chase blocked assembly of VLDL. This indicates that MTP is important for the conversion of full-length apoB-100 into VLDL. Results from experiments in which a second chase (-BFA) was introduced before the inactivation of MTP indicated that only early events in this conversion of full-length apoB-100 into VLDL were blocked by the MTP inhibitor. Together these results indicate that there is a MTP-dependent "window" in the VLDL assembly process that occurs after the completion of apoB-100 but before the major amount of lipids is added to the VLDL particle. Thus the assembly of apoB-100 VLDL from membrane-associated apoB-100 involves an early MTP-dependent phase and a late MTP-independent phase, during which the major amount of lipid is added. 相似文献