全文获取类型
收费全文 | 2007篇 |
免费 | 154篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 23篇 |
综合类 | 10篇 |
化学工业 | 693篇 |
金属工艺 | 35篇 |
机械仪表 | 22篇 |
建筑科学 | 69篇 |
矿业工程 | 7篇 |
能源动力 | 52篇 |
轻工业 | 234篇 |
水利工程 | 17篇 |
石油天然气 | 11篇 |
无线电 | 110篇 |
一般工业技术 | 367篇 |
冶金工业 | 252篇 |
原子能技术 | 6篇 |
自动化技术 | 254篇 |
出版年
2023年 | 33篇 |
2022年 | 100篇 |
2021年 | 162篇 |
2020年 | 76篇 |
2019年 | 66篇 |
2018年 | 86篇 |
2017年 | 62篇 |
2016年 | 91篇 |
2015年 | 82篇 |
2014年 | 83篇 |
2013年 | 147篇 |
2012年 | 126篇 |
2011年 | 152篇 |
2010年 | 101篇 |
2009年 | 92篇 |
2008年 | 92篇 |
2007年 | 84篇 |
2006年 | 75篇 |
2005年 | 63篇 |
2004年 | 60篇 |
2003年 | 42篇 |
2002年 | 42篇 |
2001年 | 16篇 |
2000年 | 21篇 |
1999年 | 10篇 |
1998年 | 25篇 |
1997年 | 22篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有2162条查询结果,搜索用时 250 毫秒
991.
Work on thematic thinking, an individual's preference for basing decisions and cognitive processes on thematic similarity, has been developed recently. These preferences also build the basis for idea generation (thematic ideation) and evaluation processes. Research results indicate that there are inter‐individual differences in these preferences. We apply these findings from the field of cognition to the business context and theoretically develop and empirically test a set of antecedents and consequences of thematic thinking. Results indicate that experience and positive affect are positively related to thematic thinking. The consequences that were examined, adaptation and creativity, showed relations which were reverse to the ones hypothesized based on related prior literature. Counter‐intuitively, adaptation is positively related to thematic thinking, while creativity is negatively related. We discuss theoretical and managerial implications and highlight avenues for future research on thematic thinking. 相似文献
992.
993.
Jian Wang Kaspars Berzins Diana Hicks Julia Melkers Fang Xiao Diogo Pinheiro 《Scientometrics》2012,93(2):391-411
This paper proposes a method for classifying true papers of a set of focal scientists and false papers of homonymous authors in bibliometric research processes. It directly addresses the issue of identifying papers that are not associated (??false??) with a given author. The proposed method has four steps: name and affiliation filtering, similarity score construction, author screening, and boosted trees classification. In this methodological paper we calculate error rates for our technique. Therefore, we needed to ascertain the correct attribution of each paper. To do this we constructed a small dataset of 4,253 papers allegedly belonging to a random sample of 100 authors. We apply the boosted trees algorithm to classify papers of authors with total false rate no higher than 30% (i.e. 3,862 papers of 91 authors). A one-run experiment achieves a testing misclassification error 0.55%, testing recall 99.84%, and testing precision 99.60%. A 50-run experiment shows that the median of testing classification error is 0.78% and mean 0.75%. Among the 90 authors in the testing set (one author only appeared in the training set), the algorithm successfully reduces the false rate to zero for 86 authors and misclassifies just one or two papers for each of the remaining four authors. 相似文献
994.
Docosahexanoic acid (DHA) and eicosapentanoic acid (EPA) have been shown to possess anti-carcinogenic properties in mammary cancers, both in vitro and in vivo. The objective of this study was to investigate the effect of treating three different breast cancer cell lines with DHA or EPA on cellular growth, chemotherapy efficacy, and CD95 expression and localization in the cell. MDA-MB-231, MCF-7 and SKBr-3 cells were incubated with EPA or DHA with or without chemotherapy agents [doxorubicin (dox), Herceptin]. Cell growth was assessed by WST-1 assay and CD95 expression was investigated using flow cytometry, Western blotting and confocal microscopy. DHA and EPA inhibited the growth of all three breast cancer cell lines in a dose-dependent fashion (P?<?0.05). DHA, and to a lesser extent EPA, induced the movement and raft clustering of CD95 in the cell membrane (via confocal microscopy) and the surface expression (via flow cytometry) in MDA-MB-231 cells. Neither fatty acid altered the growth/metabolic activity of the non-transformed MCF-12A breast cell line. Pre-treatment with DHA, but not EPA, improved the efficacy of dox in estrogen receptor negative MDA-MB-231 cells (P?<?0.05), but not in the other two cell lines. Pre-treating cells with DHA increased CD95 surface expression (threefold) and the plasma membrane raft content of CD95 (2fold) and FADD (>4-fold) after dox treatment, compared to dox treatment alone (P?<?0.05). This study demonstrated that pre-treatment of estrogen receptor negative MDA-MB-231 cells with DHA increased the anti-cancer effects of dox and presents evidence to suggest that this may be mediated in part by CD95-induced apoptosis. 相似文献
995.
Helen Bernard Martin Bisping Bernd Broschewitz Michael Bucher Alexandra Fetsch Doris F?rster Oliver Frandrup-Kuhr Gerd Fricke Matthias Greiner Stefan Gross Christoph-Michael H?nel Katrin Heusler Julia J?hne Norbert Kenntner Andreas Kliemant Kristian K��hn Manfred Kutzke Wulf Ladehoff Dr. Petra Luber Olaf Mosbach-Schulz Britta M��ller Albert Rampp Annette Reinecke Bettina Rosner 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2011,6(4):483-495
This is a report on the results of the work of the German EHEC Task Force on the food safety side of the EHEC O104:H4 disease outbreak investigation in Germany. During the first phase of the outbreak investigation the main goal was to identify the contaminated food. To achieve this, two different strategies were followed in parallel. One approach was a detailed trace back analysis for all salad ingredients and raw vegetables that have been served to customers at five outbreak clusters in order to identify common food sources and delivery chains. The second approach was a trace forward analysis of the supply chains of a sprout producer in order to find out if he had delivered any outbreak clusters. Both approaches revealed that contaminated sprouts from a producer in Lower Saxony highly likely had caused the outbreak. Aim of the second investigation phase was to find and stop the source of the EHEC O104:H4 bacteria. The Task Force gave recommendations on source elimination measures and collected and analysed epidemiological information in order to find out when the source was active. Next to that, a detailed trace back for batches of suspicious seeds that had been used by the sprout producer was initiated. The results from this activity formed the basis for the tracing of seeds coordinated by the European Food Safety Authority, which revealed that fenugreek seeds imported from Egypt were the most likely common link between the EHEC O104:H4 outbreaks in Germany and France. In conclusion, the newly developed outbreak investigation strategy of the task Force EHEC with close collaboration between German federal and federal state authorities and between food safety authorities, health authorities and scientists was a recipe of success and can be a model for future food-borne outbreak investigations. 相似文献
996.
997.
Andrea Wangorsch Anuja Kulkarni Annette Jamin Jelena Spiric Julia Brcker Jens Brockmeyer Vera Mahler Natalia Blanca‐Lpez Marta Ferrer Miguel Blanca Maria Torres Paqui Gomez Joan Bartra Alba García‐Moral María J. Goikoetxea Stefan Vieths Masako Toda Gianni Zoccatelli Stephan Scheurer 《Molecular nutrition & food research》2020,64(19)
998.
999.
Carreras Alberto Delgado-Luque Isabel M. Martín-Vega Francisco J. Aguayo-Torres Mari Carmen Gómez Gerardo Entrambasaguas J. Tomás Atxutegi Eneko Solozabal Ruben Blanco Bego Fajardo Jose Oscar Liberal Fidel 《Wireless Personal Communications》2019,106(4):2005-2022
Wireless Personal Communications - The principle of Cloud Radio Access Network (C-RAN) is the split of traditional base stations into Radio Remote Units (RRU) as low-cost wireless access points,... 相似文献
1000.
Linda Heintze Dorian Schmidt Theo Rodat Lydia Witt Julia Ewert Malte Kriegs Rainer Herges Christian Peifer 《International journal of molecular sciences》2020,21(23)
In this study, we aimed at the application of the concept of photopharmacology to the approved vascular endothelial growth factor receptor (VEGFR)-2 kinase inhibitor axitinib. In a previous study, we found out that the photoisomerization of axitinib’s stilbene-like double bond is unidirectional in aqueous solution due to a competing irreversible [2+2]-cycloaddition. Therefore, we next set out to azologize axitinib by means of incorporating azobenzenes as well as diazocine moieties as photoresponsive elements. Conceptually, diazocines (bridged azobenzenes) show favorable photoswitching properties compared to standard azobenzenes because the thermodynamically stable Z-isomer usually is bioinactive, and back isomerization from the bioactive E-isomer occurs thermally. Here, we report on the development of different sulfur–diazocines and carbon–diazocines attached to the axitinib pharmacophore that allow switching the VEGFR-2 activity reversibly. For the best sulfur–diazocine, we could verify in a VEGFR-2 kinase assay that the Z-isomer is biologically inactive (IC50 >> 10,000 nM), while significant VEGFR-2 inhibition can be observed after irradiation with blue light (405 nm), resulting in an IC50 value of 214 nM. In summary, we could successfully develop reversibly photoswitchable kinase inhibitors that exhibit more than 40-fold differences in biological activities upon irradiation. Moreover, we demonstrate the potential advantage of diazocine photoswitches over standard azobenzenes. 相似文献