全文获取类型
收费全文 | 3753篇 |
免费 | 42篇 |
专业分类
电工技术 | 34篇 |
综合类 | 8篇 |
化学工业 | 341篇 |
金属工艺 | 19篇 |
机械仪表 | 18篇 |
建筑科学 | 63篇 |
矿业工程 | 1篇 |
能源动力 | 35篇 |
轻工业 | 151篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 101篇 |
一般工业技术 | 189篇 |
冶金工业 | 2627篇 |
原子能技术 | 12篇 |
自动化技术 | 191篇 |
出版年
2021年 | 26篇 |
2020年 | 16篇 |
2018年 | 22篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 32篇 |
2013年 | 47篇 |
2012年 | 68篇 |
2011年 | 62篇 |
2010年 | 49篇 |
2009年 | 53篇 |
2008年 | 47篇 |
2007年 | 49篇 |
2006年 | 44篇 |
2005年 | 40篇 |
2004年 | 34篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 19篇 |
2000年 | 28篇 |
1999年 | 108篇 |
1998年 | 784篇 |
1997年 | 429篇 |
1996年 | 324篇 |
1995年 | 191篇 |
1994年 | 146篇 |
1993年 | 161篇 |
1992年 | 34篇 |
1991年 | 34篇 |
1990年 | 37篇 |
1989年 | 48篇 |
1988年 | 52篇 |
1987年 | 38篇 |
1986年 | 38篇 |
1985年 | 33篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 31篇 |
1980年 | 25篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 54篇 |
1976年 | 114篇 |
1975年 | 16篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1970年 | 15篇 |
1969年 | 22篇 |
1968年 | 17篇 |
1966年 | 22篇 |
排序方式: 共有3795条查询结果,搜索用时 15 毫秒
1.
Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia. 相似文献
2.
Hannerz Harald; Albertsen Karen; Nielsen Martin Lindhardt; Tüchsen Finn; Burr Hermann 《Canadian Metallurgical Quarterly》2004,23(3):283
This study explored whether factors related to the work environment could predict changes in body mass index (BMI) and whether the effect of psychosocial factors was dependent on baseline BMI. The sample consisted of 1,980 male employees from the Danish National Work Environment Cohort Study. Changes in BMI between 1995 and 2000 were analyzed, by multiple regression, as a function of background variables and a series of occupational variables obtained in 1995. Age, baseline BMI, job insecurity, and psychological demands predicted changes in BMI. Job insecurity and high or low psychological demands increased the likelihood of weight gain among obese employees, whereas they increased the likelihood of weight loss among employees with a low BMI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
4.
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
5.
6.
7.
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
8.
Bound-state beta decay of highly ionized atoms 总被引:1,自引:0,他引:1
9.
A self‐consistent texture model is implemented in the finite‐element code ABAQUS/Explicit®. Hardening of the slip systems is described by evolution laws for dislocation densities, and the Bauschinger effect is included. With these ingredients the cold rolling of an IF‐steel is simulated and the evolution of texture and anisotropy is examined. The use of the dislocation based hardening law is found to have a significant effect on the evolution of the anisotropic yield surface, but only very little influence on the texture. Furthermore, the hardening model is used to investigate the evolution of dislocation densities in differently oriented grains during plane strain compression. It is found that the dislocation density varies greatly depending on orientation, an observation which can help to explain the orientation dependence of recrystallization. 相似文献
10.
Hermann Ney 《Informatik-Spektrum》2003,26(2):94-102
Dieser Beitrag behandlt die Rolle des statistischen Ansatzes in der maschinellen (oder automatischen) Sprachverarbeitung.
相似文献