全文获取类型
收费全文 | 1929篇 |
免费 | 37篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 24篇 |
综合类 | 4篇 |
化学工业 | 293篇 |
金属工艺 | 17篇 |
机械仪表 | 13篇 |
建筑科学 | 51篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 168篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 75篇 |
一般工业技术 | 250篇 |
冶金工业 | 857篇 |
原子能技术 | 4篇 |
自动化技术 | 184篇 |
出版年
2022年 | 13篇 |
2021年 | 30篇 |
2020年 | 24篇 |
2019年 | 32篇 |
2018年 | 25篇 |
2017年 | 17篇 |
2016年 | 38篇 |
2015年 | 22篇 |
2014年 | 36篇 |
2013年 | 40篇 |
2012年 | 64篇 |
2011年 | 83篇 |
2010年 | 39篇 |
2009年 | 42篇 |
2008年 | 43篇 |
2007年 | 46篇 |
2006年 | 48篇 |
2005年 | 32篇 |
2004年 | 29篇 |
2003年 | 27篇 |
2002年 | 57篇 |
2001年 | 49篇 |
2000年 | 37篇 |
1999年 | 46篇 |
1998年 | 267篇 |
1997年 | 125篇 |
1996年 | 86篇 |
1995年 | 52篇 |
1994年 | 47篇 |
1993年 | 58篇 |
1992年 | 26篇 |
1991年 | 28篇 |
1990年 | 26篇 |
1989年 | 23篇 |
1988年 | 26篇 |
1987年 | 28篇 |
1986年 | 25篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 21篇 |
1976年 | 60篇 |
1975年 | 7篇 |
1973年 | 6篇 |
1970年 | 6篇 |
排序方式: 共有1967条查询结果,搜索用时 15 毫秒
21.
22.
23.
Reading frame selection of nucleic acids has important implications for protein engineering and genomics. Current methods are limited because selection of the gene of interest inevitably depends on the solubility of its translated product. Here we report the construction of the pInSALect vector, which provides strict reading frame selection without concomitant selection for protein solubility or folding. This plasmid incorporates the cis-splicing VMA intein sequence from Saccharomyces cerevisiae to facilitate the post-translational self-excision of the protein of interest, thereby eliminating potential aggregation problems. Results from two libraries of chimeric glycinamide ribonucleotide formyltransferases confirm the superior performance of pInSALect over existing reading frame selection systems. 相似文献
24.
Gade LH 《Accounts of chemical research》2002,35(7):575-582
The chemistry of transition metal amides has received new impetus in recent years due to the systematic exploitation of the amido function [NR(2)](-) in ligand design. A class of 3-fold symmetrical tripodal amido ligands has proved to be a valuable tool in the stabilization of early transition metal and main group metal complexes and complex fragments. Moreover, promising strategies for their use as chemical reagents and homogeneous catalysts have been developed. An overwiew of the current state of this field is given and the potential for further development will be highlighted. 相似文献
25.
Background
Leptin and its soluble receptor (sOB-R) are important to regulation of body composition but there are no data on the developmental variations in these plasma variables and their relationship with body composition measurements, 相似文献26.
Belletier Clément Charkhabi Morteza Pires de Andrade Silva Gustavo Ametepe Kevin Lutz Mathieu Izaute Marie 《Cognition, Technology & Work》2021,23(1):103-116
Cognition, Technology & Work - Rapid technological innovations are constantly influencing the complexification and automatization of the work lines pushing human operators to use diverse... 相似文献
27.
Software and Systems Modeling - Advances in model-based system engineering have greatly increased the predictive power of models and the analyses that can be run on them. At the same time, designs... 相似文献
28.
Silica gel or zeolites AlPO-5 and SAPO-34 are recommended as adsorbents in water-driven heat pumps because of their selective water uptake. Secondary energy, like solar energy, can be used for regeneration of loaded adsorbers. In case of the availability of only low energy levels, the use of dealuminated Y zeolite (DAY) is the better choice because of the infinitely variation of its hydrophilic properties by tailoring of the framework Si/Al ratio. Actual data on the hydrothermal stability of DAY are lacking. Thus, we report on the long-term behavior of DAY zeolites with different Si/Al ratios. 相似文献
29.
BRINKSMEIER Ekkard WALTER André NOWAG Lutz S 《金属热处理》2004,29(8):66-72
通过旋转试验和有限元分析介绍了工件在切削加工过程中产生的畸变情况,分析了工件的装夹方式、切削速度、切削深度和进刀量对100Cr6钢环圆度的影响。通过去应力退火释放冷加工诱发的残余应力后工件的圆度与切削参数有关。另外测试了被试验环的表面残余应力,其表面残余应力与装夹方式有关。将测量的装夹力作为计算参数输入,通过有限元分析方法测试了装夹方式对工件变形的影响。协同测量结果示出了装夹方式影响工件变形的一个主要因素,表面残余应力与工件的径向变形有关,最大的拉伸应力位于夹口位置。旋转切削试验结果表明,提高切削速度圆度会稍有增加;随着切削深度的加大,圆度呈下降趋势,尽管切削力增加了;进给量的增加会导致更高的切削力,因此圆度值也增加;常规的去应力退火可使被加工环的圆度值增加。 相似文献
30.
Jan Behmann Kathrin Hendriksen Ute Müller Wolfgang Büscher Lutz Plümer 《GeoInformatica》2016,20(4):693-714
Tracking the spatio-temporal activity is highly relevant for domains like security, health, and quality management. Since animal welfare became a topic in politics and legislation locomotion patterns of livestock have received increasing interest. In contrast to the monitoring of pedestrians cattle activity tracking poses special challenges to both sensors and data analysis. Interesting states are not directly observable by a single sensor. In addition, sensors must be accepted by cattle and need to be robust enough to cope with a rough environment. In this article, we introduce the novel combination of heart rate and positioning sensors. Attached to neck and chest they are less interfering than accelerometers at the ankles. Exploiting the potential of such combined sensor system that records locomotion and non-spatial information from the heart rate sensor however is challenging. We introduce a novel two level method for the activity tracking focused on the duration and sequence of activity states. We combine Support Vector Machine (SVM) with Conditional Random Field (CRF) and extend Conditional Random fields by an explicit representation of duration. The SVM characterizes local activity states, whereas the CRF addresses sequences of local states to sequences incorporating spatial and non-spatial contextual knowledge. This combination provides a reliable and comprehensive identification of defined activity patterns, as well as their chronology and durations, suitable for the integration in an activity data base. This data base is used to extract physiological parameters and promises insights into internal states such as fitness, well-being and stress. Interestingly we were able to demonstrate a significant correlation between resting pulse rate and the day of pregnancy. 相似文献