全文获取类型
收费全文 | 8147篇 |
免费 | 360篇 |
国内免费 | 53篇 |
专业分类
电工技术 | 216篇 |
综合类 | 20篇 |
化学工业 | 1791篇 |
金属工艺 | 167篇 |
机械仪表 | 207篇 |
建筑科学 | 249篇 |
矿业工程 | 9篇 |
能源动力 | 534篇 |
轻工业 | 804篇 |
水利工程 | 91篇 |
石油天然气 | 157篇 |
武器工业 | 4篇 |
无线电 | 1006篇 |
一般工业技术 | 1427篇 |
冶金工业 | 489篇 |
原子能技术 | 84篇 |
自动化技术 | 1305篇 |
出版年
2024年 | 19篇 |
2023年 | 187篇 |
2022年 | 434篇 |
2021年 | 550篇 |
2020年 | 388篇 |
2019年 | 397篇 |
2018年 | 499篇 |
2017年 | 350篇 |
2016年 | 399篇 |
2015年 | 246篇 |
2014年 | 379篇 |
2013年 | 628篇 |
2012年 | 414篇 |
2011年 | 479篇 |
2010年 | 306篇 |
2009年 | 282篇 |
2008年 | 250篇 |
2007年 | 226篇 |
2006年 | 194篇 |
2005年 | 169篇 |
2004年 | 133篇 |
2003年 | 110篇 |
2002年 | 126篇 |
2001年 | 71篇 |
2000年 | 73篇 |
1999年 | 80篇 |
1998年 | 135篇 |
1997年 | 112篇 |
1996年 | 74篇 |
1995年 | 85篇 |
1994年 | 56篇 |
1993年 | 54篇 |
1992年 | 40篇 |
1991年 | 23篇 |
1990年 | 31篇 |
1989年 | 45篇 |
1988年 | 46篇 |
1987年 | 31篇 |
1986年 | 28篇 |
1985年 | 42篇 |
1984年 | 49篇 |
1983年 | 41篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 28篇 |
1979年 | 23篇 |
1978年 | 19篇 |
1977年 | 22篇 |
1976年 | 31篇 |
1974年 | 16篇 |
排序方式: 共有8560条查询结果,搜索用时 15 毫秒
1.
PURPOSE: To assess the role postoperative mydriatics play after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (IOL) implantation in causing iris modifications and in controlling inflammation. SETTING: Outpatients Department, Ninewells Hospital, Dundee, Scotland. METHODS: The prospective study comprised 136 patients who had standardized ECCE. Half the patients used a mydriatic for 2 weeks postoperatively. Anterior chamber activity, pain, and eye redness were evaluated at 2 weeks postoperatively; pupil shape, peripheral anterior synechias, IOL position, and iris adhesions, at 6 weeks. RESULTS: Iris-lens adhesions were significantly more common in the group using a mydriatic. There was no difference between the two groups in postoperative inflammation. CONCLUSION: Mydriatics should not be used routinely after ECCE with posterior chamber IOL implantation. 相似文献
2.
This review is written to evaluate the stereoselectivity in cutaneous hydrolysis and transdermal transport of propranolol prodrug. This discussion will be useful in the development of knowledge about stereoselective cutaneous hydrolysis and its influence on stereoselective transdermal transport of many other chiral prodrugs and drugs. Propranolol prodrugs undergo stereoselective hydrolysis in hairless mouse skin homogenate and in excised skin samples during permeation; the stereoselectivity is markedly biased towards hydrolysis of the (R) isomer. Unlike the liver, the esterase activity of the skin is high in its cytosolic fraction. Most of the lipophilic propranolol prodrugs cause stereoselective permeation across hairless mouse skin. A mechanism of stereoselective permeation of propranolol prodrug across the skin has been proposed, which indicates that the stereoselectivity in permeation is resulted from the stereoselective hydrolysis of lipophilic prodrug during permeation. 相似文献
3.
4.
An assessment is made of the technical contents of flight-vehicle structures curricula at 41 U.S. universities with accredited aerospace engineering programs. The assessment is based on the technical needs for the new and projected aeronautical and space systems as well as on the likely characteristics of the aerospace engineering work environment. A number of deficiencies and areas of concern are identified and recommendations are presented for enhancing the effectiveness of flight-vehicle structures education. A number of government supported programs that can help aerospace engineering education are listed in the appendix. 相似文献
5.
Gilbert A. Hartley Ahmed Abdel-Akher Peilei Chen 《International journal for numerical methods in engineering》1992,35(9):1771-1785
Procedures are described for modelling a structural system consisting of thin Kirchhoff plates with internal patch areas capable of displacing as rigid flat surfaces. The physical prototype for these patches could be interconnection points for one-dimensional frame type elements of various shapes and layout, rigidly connected at these finite size 'joints' in the plate. The numerical procedure for modelling the thin plate is the Direct Boundary Element Method (DBEM) and a simple overview of this procedure is provided. Potential trouble spots, of which the user should be aware, are described. The paper will be of interest to structural engineers for analysis of frames having both plate and simple frame elements, for example, building frames; and also to researchers seeking the greater detail that this refined procedure can provide. As a practical tool, the methods described are computationally competitive with existing procedures, including the more rugged approaches used by building structural engineers for dynamic and torsional analysis. 相似文献
6.
A novel rapid power-on operational amplifier and a current modulation technique are used in a 10-bit 1.5-bit/stage pipelined ADC in 0.18-/spl mu/m CMOS to realize power scalability between 1 kS/s (15 /spl mu/W) and 50 MS/s (35 mW), while maintaining an SNDR of 54-56 dB for all sampling rates. The current modulated power scaling (CMPS) technique is shown to enhance the power scaleable range of current scaling by 50 times, allowing ADC power to be varied by a factor of 2500 while only varying bias currents by a factor of 50. Furthermore, the nominal power is reduced by 20%-30% by completely powering off the rapid power-on opamps during the sampling phase in the pipeline's sample-and-holds. 相似文献
7.
KS Ghenghesh AS Altomi A Elgrari MR Alosta Omar AM Sharif Eddin SS Abied 《Canadian Metallurgical Quarterly》1995,72(1-2):13-15
Twenty seven Aeromonas strains (5A. hydrophila, 8A. sobria and 14A. caviae) isolated from children with diarrhoea and 34 Aeromonas strains (9A. hydrophila, 7A. sobria an 18A. caviae) isolated from children without diarrhoea were tested from haemolysin production. The results obtained showed that haemolysin production using human, horse or sheep erythrocytes was significantly associated with A.hydrophila and A sobria but not with A.caviae, regardless of whether these strains were isolated from children with or without diarrhoea. Human or horse rather than sheep erythrocytes are recommended for use in the haemolysin assay. 相似文献
8.
Calcified and fibrotic coronary artery lesions cannot always be dilated with conventional balloon angioplasty even at high pressures. This study examines the success of excimer laser facilitated angioplasty in 38 lesions in 37 patients with lesions that failed balloon angioplasty alone. 相似文献
9.
Adrian Thomas Christopher D. Gilson Tanveer Ahmed 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):73-79
Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically. 相似文献
10.