全文获取类型
收费全文 | 4274篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 28篇 |
综合类 | 6篇 |
化学工业 | 291篇 |
金属工艺 | 30篇 |
机械仪表 | 42篇 |
建筑科学 | 68篇 |
矿业工程 | 7篇 |
能源动力 | 29篇 |
轻工业 | 158篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 260篇 |
一般工业技术 | 289篇 |
冶金工业 | 2913篇 |
原子能技术 | 20篇 |
自动化技术 | 164篇 |
出版年
2023年 | 16篇 |
2022年 | 22篇 |
2021年 | 31篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 25篇 |
2017年 | 26篇 |
2016年 | 33篇 |
2015年 | 36篇 |
2014年 | 36篇 |
2013年 | 69篇 |
2012年 | 59篇 |
2011年 | 72篇 |
2010年 | 66篇 |
2009年 | 58篇 |
2008年 | 66篇 |
2007年 | 59篇 |
2006年 | 49篇 |
2005年 | 60篇 |
2004年 | 28篇 |
2003年 | 26篇 |
2002年 | 40篇 |
2001年 | 41篇 |
2000年 | 29篇 |
1999年 | 119篇 |
1998年 | 884篇 |
1997年 | 501篇 |
1996年 | 368篇 |
1995年 | 208篇 |
1994年 | 166篇 |
1993年 | 182篇 |
1992年 | 45篇 |
1991年 | 48篇 |
1990年 | 59篇 |
1989年 | 67篇 |
1988年 | 59篇 |
1987年 | 45篇 |
1986年 | 47篇 |
1985年 | 41篇 |
1984年 | 14篇 |
1983年 | 25篇 |
1982年 | 14篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 19篇 |
1978年 | 28篇 |
1977年 | 52篇 |
1976年 | 125篇 |
1971年 | 19篇 |
1970年 | 14篇 |
排序方式: 共有4316条查询结果,搜索用时 15 毫秒
1.
2.
JB Kamien WK Bickel BJ Smith GJ Badger JR Hughes 《Canadian Metallurgical Quarterly》1997,58(4):983-991
The percentage of long-term survivors after intensive chemotherapy and the outcome of MDS patients who achieve partial remission (PR) with intensive chemotherapy (IC) are not known. Between 1981 and 1996 we treated 99 patients with de novo MDS who had high-risk MDS or progression to AML, with IC. 41 (41%) achieved CR, 16 (16%) achieved partial remission (PR), 26 (26%) had failure, and 16 (16%) died in aplasia. Eight of the patients who achieved CR were autografted, three were allografted and the remaining cases received moderate consolidation chemotherapy. After IC, the 16 PR patients fulfilled the criteria for RA in 15 cases and CMML in one case. Median PR duration was 17 months, and three PR were > 3 years (39, 50+, 82+ months). Median actuarial survival of patients who achieved PR and CR was 18 months and 20 months from the onset of IC, respectively (difference not significant). Of the 71 patients treated before 1993, with sufficient follow-up, 10 (14%) had survived > 4 years (long-term survivors). Four of them were alive in first CR after 49+ to 110+ months and probably cured, two were alive in PR after 50+ and 82+ months and four had died after 49-78 months. Long-term survivors were characterized by a significantly higher incidence of RAEB-T at diagnosis, and with normal or favourable cytogenetic findings. In patients with RAEB-T at diagnosis included before 1993, 8/23 (35%) cases who had no unfavourable karyotype had survived > 4 years. Our findings suggest that MDS patients who achieve PR with IC, and not only those who achieve CR, can benefit from this type of treatment. The percentage of long-term survivors remains low, however, and is almost restricted to patients with RAEB-T at diagnosis and no unfavourable karyotype. 相似文献
3.
4.
5.
We have compared the duration of motor block produced by four local anaesthetics administered into a chronically implanted subarachnoid catheter in rabbits. Each group (n = 6) received four different doses of amethocaine, bupivacaine, lignocaine or procaine, and the duration of the resulting motor block was assessed. Dose-response curves were plotted for each drug. As a measure of activity of the anaesthetics, we used the dose of each drug required to produce block of 60-min duration (D60 min) and the correlation between D60 min and different drug properties was examined. An inverse linear correlation (r = 0.995; P < 0.01) was observed between log D60 min and the log of the partition coefficient of the local anaesthetics. No correlation was found between the effect and degree of protein binding, pKa or molecular weight. These results suggest that, in spinal anaesthesia, the partition coefficient could be used as a predictor of the duration of anaesthetic action. 相似文献
6.
Bound-state beta decay of highly ionized atoms 总被引:1,自引:0,他引:1
7.
T. Braun K.-F. Becker M. Koch V. Bader R. Aschenbrenner H. Reichl 《Microelectronics Reliability》2005,45(9-11):1672
Automotive under-the-hood electronics often have to withstand temperatures up to 175 °C in combination with harsh environment conditions. This paper gives an overview about the reliability potential of epoxy based encapsulants for automotive applications. Therefore the resistance of epoxy molding compound against typical automotive fluids at temperature of use is analyzed. Six epoxy molding compounds available on the market, showing high temperature automotive potential have been carefully selected to undergo a media resistance testing. For this purpose a dedicated mold tool has been designed and manufactured to prepare these encapsulants for material testing. Thermo-mechanical, mechanical and thermal properties had been determined in initial state directly after molding and after storage in aggressive fluids typical for automotive applications as e.g. gas oil, automatic transmission fluid (ATF), brake fluid or accumulator acid at the respective temperature of use. 相似文献
8.
W. Shang B. Robrahn F. Golding M. H. J. Koch 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,530(3):513-520
A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system. 相似文献
9.
- In uncatalyzed reactions the esterification of stearic, oleic, and linolenic acid proceeded at the same general rate though the speed was somewhat enhanced as the degree of unsaturation of the fatty acid increased. None of the reactions went to completion, after 15 hours being 72%, 83%, and 84%, respectively, completed. Only a small fraction of the distearate was converted to the triglyceride; a greater amount of the dioleate was esterified to the trioleate and about half the dilinolenate was changed to the trilinolenate.
- Of 15 metallic fluorides studied, all afforded some catalysis, but only antimony trifluoride and zinc and cobalt fluorides were outstanding. Antimony trifluoride was the most active although in large amount it caused severe decomposition and charring of the products. Zinc fluoride had the best general properties, approaching antimony trifluoride yet causing practically no decomposition even in high concentration. Its activity was enhanced with an increase in amount, the best concentration apparently being 0.1 mole per 100 grams fatty acid. Antimony trifluoride was also better in larger amount within limits, but cobalt fluoride did not exhibit this property.
- With zinc fluoride as catalyst the reactions of stearic, oleic and linolenic acids after 15 hours were 95%, 94%, and 92%, respectively, completed. At least three-fourths of the diglycerides were converted to triglycerides. From a study of reaction velocities, zinc fluoride caused the monoglyceride to form at a rate approximately four times that of the uncatalyzed reaction and the diglyceride at a six-fold rate. The triglyceride was formed at an almost undiminished rate whereas in the uncatalyzed reaction the formation of triglyceride was diminished rapidly.
- Unsaturation and viscosity were not affected seriously in the presence of the fluorides except antimony trifluoride. Certain other fluorides caused severe darkening but without accompanying serious decomposition.
10.
Terahertz characterisation of building materials 总被引:1,自引:0,他引:1
Piesiewicz R. Kleine-Ostmann T. Krumbholz N. Mittleman D. Koch M. Kurner T. 《Electronics letters》2005,41(18):1002-1004
To obtain realistic models for propagation channels in future pico-cellular indoor terahertz communication systems it is necessary to know the reflective properties of building materials found in a typical office environment. The angular dependent reflection coefficients of different building materials were determined using terahertz time-domain spectroscopy in transmission geometry and Fresnel's equations. This approach is more efficient than a set of measurements in reflection geometry for different angles. Verification of the method with a set of such reflection measurements shows an excellent agreement. 相似文献