全文获取类型
收费全文 | 597篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 7篇 |
化学工业 | 156篇 |
金属工艺 | 7篇 |
机械仪表 | 4篇 |
建筑科学 | 66篇 |
能源动力 | 17篇 |
轻工业 | 107篇 |
水利工程 | 3篇 |
无线电 | 20篇 |
一般工业技术 | 89篇 |
冶金工业 | 33篇 |
原子能技术 | 3篇 |
自动化技术 | 97篇 |
出版年
2023年 | 8篇 |
2022年 | 20篇 |
2021年 | 24篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 21篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 23篇 |
2014年 | 35篇 |
2013年 | 40篇 |
2012年 | 42篇 |
2011年 | 47篇 |
2010年 | 35篇 |
2009年 | 37篇 |
2008年 | 30篇 |
2007年 | 34篇 |
2006年 | 31篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
排序方式: 共有618条查询结果,搜索用时 250 毫秒
21.
22.
Anja Wessely Theresa Steeb Ulrike Leiter Claus Garbe Carola Berking Markus Vincent Heppt 《International journal of molecular sciences》2020,21(23)
Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer that predominantly arises in chronically sun-damaged skin. Immunosuppression, genetic disorders such as xeroderma pigmentosum (XP), exposure to certain drugs and environmental noxae have been identified as major risk factors. Surgical removal of cSCC is the therapy of choice and mostly curative in early stages. However, a minority of patients develop locally advanced tumors or distant metastases that are still challenging to treat. Immune checkpoint blockade (ICB) targeting CTLA-4, PD-L1 and PD-1 has tremendously changed the field of oncological therapy and especially the treatment of skin cancers as tumors with a high mutational burden. In this review, we focus on the differences between cSCC and cutaneous melanoma (CM) and their implications on therapy, summarize the current evidence on ICB for the treatment of advanced cSCC and discuss the chances and pitfalls of this therapy option for this cancer entity. Furthermore, we focus on special subgroups of interest such as organ transplant recipients, patients with hematologic malignancies, XP and field cancerization. 相似文献
23.
Characterization of activated sludge flocs by confocal laser scanning microscopy and image analysis 总被引:7,自引:0,他引:7
Schmid M Thill A Purkhold U Walcher M Bottero JY Ginestet P Nielsen PH Wuertz S Wagner M 《Water research》2003,37(9):2043-2052
In this study we present a new approach to determine volumes, heterogeneity factors, and compositions of the bacterial population of activated sludge flocs by 3D confocal imaging. After staining the fresh flocs with fluorescein-isothiocyanate, 75 stacks of images (containing approx. 3000 flocs) were acquired with a confocal laser scanning microscope. The self-developed macro 3D volume and surface determination for the KS 400 software package combined the images of one stack to a 3D image and calculated the real floc volume and surface. We determined heterogeneity factors like the ratio of real floc surface to the surface of a sphere with the respective volume and the fractal dimension (D(f)). According to their significant influence on floc integrity and quality, we also investigated the chemical composition of flocs and quantified their bacterial population structure by using group-specific rRNA-targeted probes for fluorescence in situ hybridization. By a settling experiment we enriched flocs with poor settling properties and determined the above-mentioned parameters. This approach revealed shifts in floc volume, heterogeneity, and bacterial and chemical composition according to the settling quality of the flocs. 相似文献
24.
25.
While a growing number of travelers engages in consumer-generated media (CGM) use and creation, the gap between the number of users and the number of actual content creators remains large. It is important to find out what drives this minority of creators and what makes them different from those who only use CGM. Personality has been found to be a particularly influential trait that predicts behavior. The influence of personality on travel CGM creation was investigated and the results indicate that travelers’ personality traits significantly influence perceived barriers to content creation, motivations to engage in CGM creation, and specific creation behaviors. Contributions and implications are discussed from both a theoretical and a practical perspective. 相似文献
26.
27.
This survey shows that female representation in boards and management groups of large energy companies in Germany, Spain and Sweden is far from being gender-equal. Of the 464 companies surveyed, 295 (64%) had no women at all in boards or management groups and only 5% could be considered gender-equal by having 40% or more women in such positions. Interviews with energy companies confirmed current trends that gender equality efforts within decision-making in business are weak or non-existent. The findings are discussed against the background of differences in risk perceptions among women and men, evidence of women’s impact on boards and companies’ performance and the substantial risks related to unabated climate change. Research is suggested for exploring potential impacts on energy companies' performance with more women in the boards when it comes to mitigation activities. 相似文献
28.
The case for technology in developing regions 总被引:1,自引:0,他引:1
Brewer E. Demmer M. Du B. Ho M. Kam M. Nedevschi S. Pal J. Patra R. Surana S. Fall K. 《Computer》2005,38(6):25-38
Alongside good governance, technology is considered among the greatest enablers for improved quality of life. However, the majority of its benefits have been concentrated in industrialized nations and therefore limited to a fraction of the world's population. We believe that technology has a large role to play in developing regions, that "First World" technology to date has been a poor fit in these areas, and that there is thus a need for technology research for developing regions. Despite the relative infancy of technology studies in developing regions, anecdotal evidence suggests that access to technology has a beneficial economic impact. Cellular telephony is probably the most visible application, but there are many others, some of which we cover in this article. The World Bank's infoDev site catalogs hundreds of information and communications technologies (ICT) projects, albeit not all successful. Most of these projects use existing off-the-shelf technology designed for the industrialized world. Although it is clear that there are large differences in assumptions related to cost, power, and usage, there has been little work on how technology needs in developing regions differ from those of industrialized nations. We argue that Western market forces continue to meet the needs of developing regions accidentally at best. 相似文献
29.
Alanine : glyoxylate aminotransferase is one of three different enzymes used for glycine synthesis in Saccharomyces cerevisiae. The open reading frame YFL030w (named AGX1 in the following), encoding this enzyme, was identified by comparing enzyme specific activities in knockout strains. While 100% activity was detectable in the parental strain, 2% was found in a YFL030w::kanMX4 strain. The ORF found at that locus was suspected to encode alanine : glyoxylate aminotransferase because its predicted amino acid sequence showed 23% identity to the human homologue. Since the YFL030w::kanMX4 strain showed no glycine auxtrophic phenotype, AGX1 was replaced by KanMX4 in a Delta GLY1 Delta SHM1 Delta SHM2 background. These background mutations, which cause inactivation of threonine aldolase, mitochondrial and cytosolic serine hydroxymethyltransferase, respectively, lead to a conditional glycine auxotrophy. This means that growth is not possible on glucose but on ethanol as the sole carbon source. Additional disruption of AGX1 revealed a complete glycine auxotrophy. Complementation was observed by transformation with a plasmid-encoded AGX1. 相似文献
30.
An optimised structure is one which uses the smallest quantity of the best material to perform its function, with adequate
safety factor or margin for error. Structural optimisation occurs not only in mechanical engineering, but also in nature:
plants with hollow stems or stalks gain a height advantage, and are thus more efficient, by approaching the optimum shape.
Here we consider the optimisation of orthotropic tubes, typifying, in a mechanical sense, stalk and stem. The stiffness and
strength of orthotropic tubes of initially circular section are reviewed, and diagrams are proposed which allow the optimum
section shape to be selected. 相似文献