全文获取类型
收费全文 | 14033篇 |
免费 | 1805篇 |
国内免费 | 831篇 |
专业分类
电工技术 | 784篇 |
综合类 | 1526篇 |
化学工业 | 855篇 |
金属工艺 | 1867篇 |
机械仪表 | 1712篇 |
建筑科学 | 3453篇 |
矿业工程 | 419篇 |
能源动力 | 344篇 |
轻工业 | 194篇 |
水利工程 | 745篇 |
石油天然气 | 612篇 |
武器工业 | 158篇 |
无线电 | 1052篇 |
一般工业技术 | 1363篇 |
冶金工业 | 352篇 |
原子能技术 | 61篇 |
自动化技术 | 1172篇 |
出版年
2024年 | 79篇 |
2023年 | 242篇 |
2022年 | 416篇 |
2021年 | 532篇 |
2020年 | 500篇 |
2019年 | 478篇 |
2018年 | 437篇 |
2017年 | 539篇 |
2016年 | 562篇 |
2015年 | 618篇 |
2014年 | 929篇 |
2013年 | 901篇 |
2012年 | 1066篇 |
2011年 | 1146篇 |
2010年 | 799篇 |
2009年 | 816篇 |
2008年 | 705篇 |
2007年 | 916篇 |
2006年 | 849篇 |
2005年 | 720篇 |
2004年 | 605篇 |
2003年 | 531篇 |
2002年 | 386篇 |
2001年 | 354篇 |
2000年 | 313篇 |
1999年 | 251篇 |
1998年 | 200篇 |
1997年 | 170篇 |
1996年 | 117篇 |
1995年 | 106篇 |
1994年 | 88篇 |
1993年 | 63篇 |
1992年 | 45篇 |
1991年 | 38篇 |
1990年 | 43篇 |
1989年 | 32篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
51.
Motion capture cannot generate cartoon‐style animation directly. We emulate the rubber‐like exaggerations common in traditional character animation as a means of converting motion capture data into cartoon‐like movement. We achieve this using trajectory‐based motion exaggeration while allowing the violation of link‐length constraints. We extend this technique to obtain smooth, rubber‐like motion by dividing the original links into shorter sub‐links and computing the positions of joints using Bézier curve interpolation and a mass‐spring simulation. This method is fast enough to be used in real time. 相似文献
52.
The aircraft lap joints are inspected with an enhanced visual inspection technique named “Edge of Light”, which is patented
by the NRC Institute for Aerospace Research. This technique is applicable for rapid detection of possible hidden corrosion
in lap joints. The surface deformation due to hidden corrosion can be characterized by this optical-based inspection method.
In this study, a calibration procedure is developed to quantify the lap joint surface deformation. The effect of surface reflectivity
is investigated with the solid film highlighting technique (SolidHiTM), which helps achieve a uniform reflectivity during the inspection. The efficiency of the technique is demonstrated with
the experimental results.
This work is supported by NRC-IAR New Initiative Research Funding. 相似文献
53.
54.
55.
56.
57.
58.
59.
Li S.-M.Li S.-S.Chang D.-G. 《工程设计学报》2017,(2):182-186
To find out the causes of vibration and noise of the trigeminal universal joint which appeared in the installation and use process, the additional moment distribution with the varies of the input shaft angular and the deflection angle was analyzed. Kinematics diagrams of the trigeminal universal joint when the output shaft installed by single radial bearing or twin radial bearing were established. The system coordinates were established under the two installation ways, and the motion equations were established by the direction cosine matrix tools. It indicated that the trigeminal universal joint installed by the single radial bearing was an approximately isometric speed transmission, and was a constant velocity transmission with twin radial bearing installed. Furthermore, the additional moment component on the input shaft and the output shaft was analyzed under the two installation ways. According to the virtual displacement principle, the additional moment on the tripod universal joint when the output shaft installed by twin radial bearing and single radial bearing were determined. When installed by single radial bearing, the deflection moment exists and the vibration frequency of additional moment was three times of the input shaft as a sine curve. The variation trend of the additional moment was straight up with the increase of deflection angle. When installed by twin radial bearing, the deflection moment was zero and the additional moment increased gradually with the increase of deflection angle but did not fluctuate. The analysis revealed that additional moment existed in the trigeminal universal joint system under both installation ways would produce bending vibration. This study is of great significance to study the causes of vibration and determine the nonlinear dynamics of the system. 相似文献
60.
Peng Chuanqi Gao Xiaofei Xu Jing Du Bujie Ning Xuhui Tang Shaoheng Bachoo Robert M. Yu Mengxiao Ge Woo-Ping Zheng Jie 《Nano Research》2017,10(4):1366-1376
A major clinical translational challenge in nanomedicine is the potential of toxicity associated with the uptake and long-term retention of non-degradable nanoparticles (NPs) in major organs.The development of inorganic NPs that undergo renal clearance could potentially resolve this significant biosafety concern.However,it remains unclear whether inorganic NPs that can be excreted by the kidneys remain capable of targeting tumors with poor permeability.Glioblastoma multiforme,the most malignant orthotopic brain tumor,presents a unique challenge for NP delivery because of the blood-brain barrier and robust blood-tumor barrier of reactive microglia and macroglia in the tumor microenvironment.Herein,we used an orthotopic murine glioma model to investigate the passive targeting of glutathione-coated gold nanoparticles (AuNPs) of 3 nm in diameter that undergo renal clearance and 18-nm AuNPs that fail to undergo renal clearance.Remarkably, we report that 3-nm AuNPs were able to target intracranial tumor tissues with higher efficiency (2.3x relative to surrounding non-tumor normal brain tissues) and greater specificity (3.0x)than did the larger AuNPs.Pharmacokinetics studies suggested that the higher glioma targeting ability of the 3-nm AuNPs may be attributed to the longer retention time in circulation.The total accumulation of the 3-nm AuNPs in major organs was significantly less (8.4x) than that of the 18-nm AuNPs.Microscopic imaging of blood vessels and renal-clearable AuNPs showed extravasation of NPs from the leaky blood-tumor barrier into the tumor interstitium.Taken together,our results suggest that the 3-nm AuNPs,characterized by enhanced permeability and retention,are able to target brain tumors and undergo renal clearance. 相似文献