全文获取类型
收费全文 | 664篇 |
免费 | 46篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 285篇 |
金属工艺 | 5篇 |
机械仪表 | 17篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 183篇 |
水利工程 | 2篇 |
无线电 | 22篇 |
一般工业技术 | 58篇 |
冶金工业 | 11篇 |
原子能技术 | 11篇 |
自动化技术 | 75篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 76篇 |
2021年 | 79篇 |
2020年 | 22篇 |
2019年 | 19篇 |
2018年 | 26篇 |
2017年 | 28篇 |
2016年 | 31篇 |
2015年 | 23篇 |
2014年 | 30篇 |
2013年 | 42篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 39篇 |
2009年 | 28篇 |
2008年 | 33篇 |
2007年 | 25篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 14篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有711条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Antonella Gori Cecilia Brunetti Luana Beatriz dos Santos Nascimento Giovanni Marino Lucia Guidi Francesco Ferrini Mauro Centritto Alessio Fini Massimiliano Tattini 《International journal of molecular sciences》2021,22(15)
Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate. 相似文献
85.
This paper presents the design of a new adaptive optimization‐based second‐order sliding mode control algorithm for uncertain nonlinear systems. It is designed on the basis of a second‐order sliding mode control with optimal reaching, with the aim of reducing the control effort while maintaining all the positive aspects in terms of finite‐time convergence and robustness in front of matched uncertainties. These features are beneficial to guarantee good performance in case of vehicle dynamics control, a crucial topic in the light of the increasing demand of semiautonomous and autonomous driving capabilities in commercial vehicles. The new proposal is theoretically analyzed, as well as verified relying on an extensive comparative study, carried out on a realistic simulator of a 4‐wheeled vehicle, in the case of a lateral stability control system. 相似文献
86.
87.
Maria Carmela Annosi Alberto Monti Antonella Martini 《Creativity & Innovation Management》2020,29(3):528-545
Previous research has shown the importance of individual learning goal orientation for both job and task performance and consequently organizational performance. Despite its importance, knowledge on the antecedents of learning goal orientation remains scarce, especially in the context of self‐managing team‐based organizations. In fact, most of the research on goal orientation antecedents has been focused on individual characteristics, belief, and ability, while the contextual factors that might influence them remain unspecified. We build on and further extend earlier studies by jointly exploring the role of individual and contextual factors affecting individual learning orientation. In particular, this study combines individual informal social network, self‐efficacy, performance feedbacks, and team identification into a model that explains individuals' learning goal orientation within self‐managing team‐based organizations. The model was empirically tested on a sample of 104 individuals belonging to an R&D organization relying on self‐managing teams. Results show that performance feedback has a negative direct effect, while team identification has a positive direct effect on individual learning goal orientation. In addition, we found that individual self‐efficacy is a mediator of the relationships between performance feedback and brokerage in the advice network and individual learning goal orientation. Finally, we did not find a relationship between centrality in the friendship network and individual learning goal orientation. 相似文献
88.
89.
Structure–Activity Relationships of Benzenesulfonamide‐Based Inhibitors towards Carbonic Anhydrase Isoform Specificity 下载免费PDF全文
Avni Bhatt Dr. Brian P. Mahon Vinicius Wilian D. Cruzeiro Dr. Benedetta Cornelio Dr. Marie Laronze‐Cochard Dr. Mariangela Ceruso Prof. Dr. Janos Sapi Dr. Graham A. Rance Prof. Dr. Andrei N. Khlobystov Assoc. Prof. Dr. Antonella Fontana Prof. Dr. Adrian Roitberg Prof. Dr. Claudiu T. Supuran Prof. Dr. Robert McKenna 《Chembiochem : a European journal of chemical biology》2017,18(2):213-222
Carbonic anhydrases (CAs) are implicated in a wide range of diseases, including the upregulation of isoforms CA IX and XII in many aggressive cancers. However, effective inhibition of disease‐implicated CAs should minimally affect the ubiquitously expressed isoforms, including CA I and II, to improve directed distribution of the inhibitors to the cancer‐associated isoforms and reduce side effects. Four benzenesulfonamide‐based inhibitors were synthesized by using the tail approach and displayed nanomolar affinities for several CA isoforms. The crystal structures of the inhibitors bound to a CA IX mimic and CA II are presented. Further in silico modeling was performed with the inhibitors docked into CA I and XII to identify residues that contributed to or hindered their binding interactions. These structural studies demonstrated that active‐site residues lining the hydrophobic pocket, especially positions 92 and 131, dictate the positional binding and affinity of inhibitors, whereas the tail groups modulate CA isoform specificity. Geometry optimizations were performed on each ligand in the crystal structures and showed that the energetic penalties of the inhibitor conformations were negligible compared to the gains from active‐site interactions. These studies further our understanding of obtaining isoform specificity when designing small molecule CA inhibitors. 相似文献
90.
Gottardini E Cristofori A Cristofolini F Maccherini S Ferretti M 《The Science of the total environment》2008,402(2-3):299-305
A fully randomized sampling design was adopted to test whether pollen viability of Austrian pine (Pinus nigra Arnold) was impacted by NO(2) pollution. Spatial strata (500500 m each) with high (41.9-44.6 microg m(-3)) and low (15.4-21.0 microg m(-3)) NO(2) were selected from a defined population in a small area (236.5 km(2), <200 m range in elevation) in Northern Italy. Pollen viability was measured by means of the Tetrazolium (TTC) test. Analysis of variance by means of a generalised linear model showed that NO(2) was a significant factor (P=0.0425) affecting pollen viability. Within the treatment, no significant differences were detected among replicates. Within each replicate, sampling unit data were significantly different (P=0.000) and this suggested some improvement in the applied sampling design was needed. Pollen viability was significantly related to pollen germination (P<0.01) and tube length (P<0.01). This suggested a possible impact of NO(2) on the regeneration of Austrian pine in polluted environments. 相似文献