全文获取类型
收费全文 | 975篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 1篇 |
化学工业 | 263篇 |
金属工艺 | 18篇 |
机械仪表 | 18篇 |
建筑科学 | 13篇 |
矿业工程 | 1篇 |
能源动力 | 58篇 |
轻工业 | 62篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 67篇 |
一般工业技术 | 236篇 |
冶金工业 | 115篇 |
原子能技术 | 20篇 |
自动化技术 | 99篇 |
出版年
2023年 | 12篇 |
2022年 | 27篇 |
2021年 | 39篇 |
2020年 | 28篇 |
2019年 | 37篇 |
2018年 | 46篇 |
2017年 | 21篇 |
2016年 | 30篇 |
2015年 | 30篇 |
2014年 | 33篇 |
2013年 | 69篇 |
2012年 | 45篇 |
2011年 | 53篇 |
2010年 | 32篇 |
2009年 | 40篇 |
2008年 | 29篇 |
2007年 | 37篇 |
2006年 | 26篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 21篇 |
1997年 | 27篇 |
1996年 | 15篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有1007条查询结果,搜索用时 15 毫秒
1.
In this work, the effect of ZrB2 (0, 5, 10 and 20?vol%) ceramic reinforcement on densification, structure, and properties of mechanically alloyed Al was investigated. The milling of Al-ZrB2 powder compositions resulted in formation of agglomerates with varied size. In particular, the size of agglomerates was reduced considerably with increased addition of ZrB2 to Al. Interestingly, the densification of hot pressed Al increased from 96.06% to 99.22% with ZrB2 addition. The reduction of agglomerates size was attributed to the enhanced densification of Al-ZrB2 composites. Pure Al showed relatively low hardness (0.94?GPa) and it was improved to 1.78?GPa with the addition of 20?vol% ZrB2. The mechanical properties have significantly been improved for Al-ZrB2 composites. Especially Al - 20?vol% ZrB2 possessed a very high yield strength (529?MPa), compressive strength (630?MPa) and compressive strain of 19.25%. Realization of such a good combination of mechanical properties is the highest ever reported for Al composites so far in the literature. The coefficient of friction (COF) of Al-ZrB2 varied narrowly between 0.33 and 0.40 after dry sliding wear against steel disc. The wear rate of Al-ZrB2 composites was within mild wear regime and varied between 98.88?×?10?6 and 34.66?×?10?6 mm3/Nm. Among all the compositions, Al - 20?vol% ZrB2 composite exhibited the lowest wear rate and high wear rate was noted for pure Al. Mild abrasion, tribo-oxidation, third body wear (wear debris) and delamination were the major material removal mechanisms for Al-ZrB2 composites. Overall the hardness, strength and wear resistance of Al - 20?vol% ZrB2 composite was improved by 84.3%, 84.3% and 64.2%, respectively when compared to pure Al. 相似文献
2.
3.
Morampudi Mahesh Kumar Prasad Munaga V. N. K. Raju U. S. N. 《Multimedia Tools and Applications》2020,79(27-28):19215-19237
Multimedia Tools and Applications - Rapid advancement in technology has led to the use of biometric authentication in every field. In particular, from the past few years, iris recognition systems... 相似文献
4.
Murugavel Raju 《电子设计应用》2007,(5):100-102
目前,医疗电器OEM厂商正在开发技术含量更高的、用于治疗和监控常见疾病的个人保健设备。这些产品价格合理,极大提高了医疗保健质量。MCU在家用血压计、肺活量计、脉搏血氧计及心率监测器等便携式医疗设备中起着重要作用。大多数此类产品中的实际生理信号是模拟信号,在测量、监控或显示前需要进行放大、过滤等处理。 相似文献
5.
6.
The present paper demonstrates the applicability of population based search optimization method, namely, Differential Evolution
(DE) to a case study of Mahi Bajaj Sagar Project (MBSP), India. Ten different strategies of DE are employed to assess the
ability of DE for solving higher dimensional problems as an alternative methodology for irrigation planning. The parameters
considered in DE are population size, crossover constant and weighting factor. Linear Programming (LP) is utilized as a comparative
approach to assess the ability of DE. Comparison of results of LP and the 10 DE strategies for the given parameters indicated
that both the results are comparable even for high dimensional problems. Extensive sensitivity analysis studies, performed
for 3,600 combinations of above parameters for the 10 DE strategies suggested that DE/rand-to-best/1/bin strategy is the best
strategy giving maximum benefits taking minimum CPU time. It is concluded that DE can be utilized for efficient planning of
any irrigation system with suitable modifications. 相似文献
7.
8.
9.
Bright red luminescent Eu3+ doped polyvinyl alcohol (PVA) films were made by solution casting technique. The emission performance of these films was studied from the measurement of excitation, emission, and lifetimes. On irradiation with an UV source, the doped films emitted bright red light. Such luminescent polymer films are expected to find potential applications as new optical materials. Emission process in the system was explained by an energy level scheme. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3273–3276, 2006 相似文献
10.
Pregnant rats were fed a high carbohydrate diet containing either 1% trilinolein or 1% trilinolein with 0.2% methyl sterculate
from 18 day gestation to 21 day postpartum. The pups were weaned at 21 days and continued on the same diet for an additional
10 days. The microsomal stearyl CoA desaturase activities of the liver were effectively inhibited. Liver triglycerides showed
increases in the saturated fatty acids concentrations at the expense of the corresponding monoenes. The concentration ofcis 6–7 octadecenoic acid was elevated. In liver phospholipids, the concentration of stearic acid was increased without a corresponding
decrease in the oleic acid content. A drastic decrease in the nervonic acid (24∶1, n−9) concentration of liver sphingomyelin
was observed. The lipids of the brain did not contain sterculic acid, and brain desaturase activity was unaffected. There
was no significant change in the concentration of monoenoic acids from 16∶1 to 22∶1. However, nervonic acid was decreased
by 32%. These results suggest that brain nervonic acid may be derived from a precursor other than oleic acid. 相似文献