全文获取类型
收费全文 | 21497篇 |
免费 | 856篇 |
国内免费 | 319篇 |
专业分类
电工技术 | 488篇 |
综合类 | 543篇 |
化学工业 | 3876篇 |
金属工艺 | 527篇 |
机械仪表 | 746篇 |
建筑科学 | 871篇 |
矿业工程 | 180篇 |
能源动力 | 577篇 |
轻工业 | 2104篇 |
水利工程 | 246篇 |
石油天然气 | 177篇 |
武器工业 | 27篇 |
无线电 | 2481篇 |
一般工业技术 | 2912篇 |
冶金工业 | 3718篇 |
原子能技术 | 170篇 |
自动化技术 | 3029篇 |
出版年
2023年 | 116篇 |
2022年 | 367篇 |
2021年 | 503篇 |
2020年 | 297篇 |
2019年 | 361篇 |
2018年 | 409篇 |
2017年 | 376篇 |
2016年 | 423篇 |
2015年 | 364篇 |
2014年 | 561篇 |
2013年 | 1065篇 |
2012年 | 846篇 |
2011年 | 1022篇 |
2010年 | 775篇 |
2009年 | 855篇 |
2008年 | 834篇 |
2007年 | 854篇 |
2006年 | 733篇 |
2005年 | 634篇 |
2004年 | 705篇 |
2003年 | 915篇 |
2002年 | 1198篇 |
2001年 | 1021篇 |
2000年 | 592篇 |
1999年 | 544篇 |
1998年 | 1348篇 |
1997年 | 862篇 |
1996年 | 642篇 |
1995年 | 431篇 |
1994年 | 318篇 |
1993年 | 352篇 |
1992年 | 195篇 |
1991年 | 152篇 |
1990年 | 146篇 |
1989年 | 136篇 |
1988年 | 132篇 |
1987年 | 110篇 |
1986年 | 112篇 |
1985年 | 155篇 |
1984年 | 87篇 |
1983年 | 90篇 |
1982年 | 83篇 |
1981年 | 106篇 |
1980年 | 99篇 |
1979年 | 62篇 |
1978年 | 49篇 |
1977年 | 101篇 |
1976年 | 192篇 |
1975年 | 51篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
31.
We managed four cases of lymphorrhea after extraperitoneal pelvic lymphadenectomy by means of minocycline instillation into the cavity around the drainage tube. Two patients had concomitantly undergone cystectomy and one prostatectomy via the extraperitoneal approach. In all four cases, the lymphorrhea markedly subsided, which dramatically shortened the duration of drainage. No side effects occurred. These findings indicate that minocycline instillation is an efficacious treatment for lymphorrhea. 相似文献
32.
Biesemans S. Hendriks M. Kubicek S. De Meyer K. 《Electron Devices, IEEE Transactions on》1998,45(6):1310-1316
A method to analyze the accuracy of the extracted values for the channel length (Leff) and series resistance (Rs) of MOSFET devices is presented. The analysis is based on a statistical argument being the variance σ of the extracted results. This variance is found to be a good measure for the accuracy of the particular extraction method used. It is shown that, in the case of deep submicron technologies, errors as large as 200 nm for ΔL can be made for these extraction methods depending on the process design and the process control. The use of a single transistor method is suggested as a possible solution to the low accuracy of the L-array methods 相似文献
33.
The influence of ointment formulation on the stability, the in-vitro release and the in-vivo absorption through the skin of rabbits was investigated. The choice of the selected ointments has no influence on the drug stability with the exception of an acidified emulsion base. A good correlation between in-vitro release and in-vivo absorption was found revealing that metronidazole was quickly released and effectively absorbed from a polyethylene glycol base. 相似文献
34.
M. L. Rojas-Cervantes A. J. Lopez-Peinado J. De D. Lopez-Gonzalez F. CarrascO-Marin 《Journal of Materials Science》1996,31(2):437-444
Some zirconia-supported vanadium oxides have been prepared by sol-gel method and characterized by different techniques. The vanadium content exerts an effect on the area and pore-size of precursors and samples calcined. The presence of vanadium also affects the decomposition of precursors into ZrO2 and to its phase transformation, as well as the formation of fibres, as shown by SEM-EDX. XPS analyses show the presence of two species of vanadium at the surface, V5– and V4+, the percentage of each one depending on the load of vanadium in the catalyst. 相似文献
35.
36.
Mei Xuan Xu Wen Guang Liu Yun Lin Guan Zuo Peng Bi Kang De Yao 《Polymer International》1995,38(2):205-209
The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties. 相似文献
37.
Probabilistic Visual Cryptography Schemes 总被引:1,自引:0,他引:1
38.
39.
Ching-Te Chuang De V. Shih-Lien Lu Soumyanath K. Partovi H. Sakurai T. 《Design & Test of Computers, IEEE》1998,15(3):119-124
Microprocessor and other lC performance continues to improve at historic rates, with no visible end in sight for the next 10 years. However, we are starting to encounter a power wall. This is true for high-performance components as well as for low-power chips with a very limited energy budget offered by batteries. We need to find ways to manage power and energy consumption on all fronts-technology, design, and architecture-without compromising performance. Otherwise, we may face discontinuation of Moore's law for the semiconductor industry in the near future. This would be triggered not by any difficulty in the scaling of process technology but by formidable barriers posed by packaging and cooling, inefficacy of power delivery, and energy constraints dictated by battery technology, which is advancing at a very lukewarm pace 相似文献
40.
To study the conservation of peroxisomal targeting signals, we have determined the intracellular localization of human peroxisomal catalase when expressed in yeast. Using immunofluorescence, differential centrifugation and immunoelectron microscopy, we show that the protein is targeted to the peroxisomes of the heterologous cell and assembled in its active tetrameric form. These data show the conservation of the catalase targeting signal and import specificity between human and yeast peroxisomes. 相似文献