全文获取类型
收费全文 | 22490篇 |
免费 | 817篇 |
国内免费 | 319篇 |
专业分类
电工技术 | 463篇 |
综合类 | 543篇 |
化学工业 | 3719篇 |
金属工艺 | 516篇 |
机械仪表 | 727篇 |
建筑科学 | 847篇 |
矿业工程 | 180篇 |
能源动力 | 559篇 |
轻工业 | 2073篇 |
水利工程 | 243篇 |
石油天然气 | 178篇 |
武器工业 | 27篇 |
无线电 | 2368篇 |
一般工业技术 | 2775篇 |
冶金工业 | 5417篇 |
原子能技术 | 168篇 |
自动化技术 | 2823篇 |
出版年
2023年 | 109篇 |
2022年 | 340篇 |
2021年 | 463篇 |
2020年 | 264篇 |
2019年 | 332篇 |
2018年 | 382篇 |
2017年 | 358篇 |
2016年 | 397篇 |
2015年 | 347篇 |
2014年 | 524篇 |
2013年 | 1013篇 |
2012年 | 790篇 |
2011年 | 967篇 |
2010年 | 744篇 |
2009年 | 810篇 |
2008年 | 795篇 |
2007年 | 814篇 |
2006年 | 703篇 |
2005年 | 603篇 |
2004年 | 681篇 |
2003年 | 899篇 |
2002年 | 1185篇 |
2001年 | 1013篇 |
2000年 | 589篇 |
1999年 | 604篇 |
1998年 | 1929篇 |
1997年 | 1195篇 |
1996年 | 827篇 |
1995年 | 540篇 |
1994年 | 387篇 |
1993年 | 468篇 |
1992年 | 203篇 |
1991年 | 162篇 |
1990年 | 158篇 |
1989年 | 150篇 |
1988年 | 141篇 |
1987年 | 120篇 |
1986年 | 121篇 |
1985年 | 156篇 |
1984年 | 86篇 |
1983年 | 94篇 |
1982年 | 89篇 |
1981年 | 112篇 |
1980年 | 114篇 |
1979年 | 61篇 |
1978年 | 52篇 |
1977年 | 127篇 |
1976年 | 265篇 |
1975年 | 54篇 |
1973年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
21.
A dedicated low-power CMOS transponder microchip is presented as part of a novel telemetry implant for biomedical applications. This mixed analog-digital circuit contains an identification code and collects information on physiological parameters, i.e., body temperature and physical activity, and on the status of the battery. To minimize the amount of data to be transmitted, a dedicated signal processing algorithm is embedded within its circuitry. All telemetry functions (encoding, modulation, generation of the carrier) are implemented on the integrated circuit. Emphasis is on a high degree of flexibility towards sensor inputs and internal data management, extreme miniaturization, and low-power consumption to allow a long implantation lifetime 相似文献
22.
Crupi F. Kaczer B. Groeseneken G. De Keersgieter A. 《Electron Device Letters, IEEE》2003,24(4):278-280
In this letter, we report new findings in the relation between channel hot-carrier (CHC) degradation and gate-oxide breakdown (BD) in short-channel nMOSFETS biased at V/sub G/>V/sub D/. We observe that the time-to-BD is strongly reduced in the hot carrier regime and that although the channel hot-electron injection into the oxide occurs mainly at the drain side, stress-induced leakage current (SILC) generation and oxide BD always occur at the source side. The results of these measurements indicate that not solely the energy of the injected electrons but also the oxide electric field is determinant in the oxide BD process. 相似文献
23.
24.
25.
26.
J M Degroodt B Wyhowski de Bukanski J De Groof H Beernaert 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1991,192(5):430-432
A method has been developed for the analysis of cimaterol and clenbuterol residues in liver, with detection limits of 0.25 micrograms/kg and 0.5 micrograms/kg, respectively. The recovery varied from 55% to 60%. After extraction, a clean-up procedure with Baker-spe C-18 columns was performed. The two chemical compounds of interest were eluted with methanol. Cimaterol and clenbuterol were quantitatively determined by high-performance liquid chromatography (HPLC) using an RP-Select B (5 microns) column and a post-column reaction procedure. The positive results were confirmed by high-performance thin-layer chromatography (HPTLC) as this technique reaches the same level of sensitivity as the HPLC method. 相似文献
27.
28.
AA De Smet 《Canadian Metallurgical Quarterly》1993,22(7):479-484
Magnetic resonance (MR) images of skeletal muscle tears can clearly delineate the severity of muscle injury. Although MR imaging is seldom necessary in patients with acute muscle trauma, it can be helpful in deciding on clinical management. The two major MR findings in acute muscle tears are deformity of the muscle and the presence of abnormal signal reflecting hemorrhage and edema. In acute tears, methemoglobin within the extravascular blood causes high-signal areas on both T1- and T2-weighted images. With partial tears, the blood may dissect in a distinctive linear pattern along the muscle bundles and fibers. As healing begins, the muscle signal diminishes, first on the T1-weighted images and then on the T2-weighted images. When there is residual abnormal signal on images obtained more than several months after the injury, it is presumed to represent hemorrhage from recurrent tears. In patients with a questionable history of a remote injury, the clinical presentation may be that of persistent pain or a soft tissue mass. In these cases MR imaging may identify the cause of the pain and can exclude a neoplasm by proving that the mass is a hypertrophied or retracted muscle. Thus, MR imaging has a limited, but occasionally important role in selected patients with skeletal muscle tears. 相似文献
29.
30.