全文获取类型
收费全文 | 16932篇 |
免费 | 617篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 158篇 |
综合类 | 33篇 |
化学工业 | 2910篇 |
金属工艺 | 297篇 |
机械仪表 | 226篇 |
建筑科学 | 743篇 |
矿业工程 | 43篇 |
能源动力 | 329篇 |
轻工业 | 6021篇 |
水利工程 | 70篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 970篇 |
一般工业技术 | 2409篇 |
冶金工业 | 1469篇 |
原子能技术 | 97篇 |
自动化技术 | 1771篇 |
出版年
2023年 | 111篇 |
2022年 | 154篇 |
2021年 | 327篇 |
2020年 | 231篇 |
2019年 | 238篇 |
2018年 | 264篇 |
2017年 | 261篇 |
2016年 | 380篇 |
2015年 | 395篇 |
2014年 | 458篇 |
2013年 | 658篇 |
2012年 | 627篇 |
2011年 | 814篇 |
2010年 | 587篇 |
2009年 | 566篇 |
2008年 | 615篇 |
2007年 | 572篇 |
2006年 | 433篇 |
2005年 | 359篇 |
2004年 | 308篇 |
2003年 | 281篇 |
2002年 | 259篇 |
2001年 | 202篇 |
2000年 | 216篇 |
1999年 | 221篇 |
1998年 | 456篇 |
1997年 | 338篇 |
1996年 | 280篇 |
1995年 | 182篇 |
1994年 | 150篇 |
1993年 | 170篇 |
1992年 | 121篇 |
1990年 | 126篇 |
1989年 | 126篇 |
1987年 | 121篇 |
1984年 | 109篇 |
1977年 | 146篇 |
1976年 | 167篇 |
1916年 | 108篇 |
1915年 | 106篇 |
1913年 | 106篇 |
1912年 | 135篇 |
1911年 | 115篇 |
1910年 | 122篇 |
1909年 | 136篇 |
1908年 | 132篇 |
1907年 | 129篇 |
1906年 | 130篇 |
1905年 | 129篇 |
1904年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 656 毫秒
21.
22.
Steffen Vojacek Lukas Schulig Nathalie Wössner Norman Geist Prof. Dr. Walter Langel Prof. Dr. Manfred Jung Prof. Dr. Dennis Schade Prof. Dr. Andreas Link 《ChemMedChem》2019,14(8):853-864
Indoles are privileged structures in medicinal and bioorganic chemistry that are particularly well suited to serve as platforms for diversity. Among many other therapeutic areas, the indole scaffold has been used to design aromatic compounds useful to interfere with enzymes engaged in the regulation of substrate acylation status, such as sirtuins. However, the planarity of the indole ring is not necessarily optimal for all target enzymes, especially when functionalization with aromatic side chains is required. Replacement of flat scaffolds by nonplanar molecular cores dominated by sp3 hybridization is a common strategy to avoid the disadvantages associated with poor solubility and high promiscuity, while covering less-well-explored areas of chemical space. Thus, we synthesized fragment-like tetrahydroindoles suitable for fragment-based drug discovery as well as a well-characterized small library intended as multipurpose screening compounds. For proof of principle, these compounds were screened against sirtuins 1–3, enzymes known to be addressable by indoles. We found that 2,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxamides are potent and selective SIRT2 inhibitors. Compound 16 t displayed an IC50 value of 0.98 μm and could serve as exquisite starting point for hit-to-lead profiling. 相似文献
23.
High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis 下载免费PDF全文
Bruna M. Azevedo Flávio L. Schmidt Helena M. A. Bolini 《International Journal of Food Science & Technology》2015,50(6):1374-1381
The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose. 相似文献
24.
Daniel Whittaker Andreas Geist Giuseppe Modolo Robin Taylor Mark Sarsfield Andreas Wilden 《溶剂提取与离子交换》2018,36(3):223-256
Over the last decade there has been much interest in the applications of diglycolamide (DGA) ligands for the extraction of the trivalent lanthanide and actinide ions from PUREX high active raffinates or dissolved spent nuclear fuel. Of the DGAs, the N,N,N’,N’-tetraoctyldiglycolamide (TODGA) is the best known and most widely studied. A number of new actinide separation processes have been proposed based on extraction with TODGA. This review covers TODGA-based processes and extraction data, specifically focusing on how phase modifiers have been used to increase metal loading and thus enhance the operating process envelopes. Effects of third phase formation and the organic phase speciation are reviewed in this context. Relevant aspects of the extraction chemistry of important solvents (TODGA-modifier-diluent combinations) are described and their performances demonstrated by a consideration of the published flowsheet tests. It is seen that modifiers are successfully enabling the use of TODGA in actinide separation processes but to date the identification and testing of suitable modifiers has been rather empirical. There is a growing understanding of the fundamental chemistry occurring in the organic phase and how that affects extractant speciation and metal loading capacity but studies are still needed if TODGA-based flowsheets are to become an industrially deployable option for minor actinide (MA) recovery processes. 相似文献
25.
Freddy A. Bernal Dr. Marcel Kaiser Prof. Dr. Bernhard Wünsch Prof. Dr. Thomas J. Schmidt 《ChemMedChem》2020,15(1):68-78
Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model. 相似文献
26.
27.
Dr. Hui Qiu Richard Caldwell Dr. Lesley Liu-Bujalski Dr. Andreas Goutopoulos Reinaldo Jones Justin Potnick Dr. Brian Sherer Dr. Andrew Bender Dr. Roland Grenningloh Dr. Daigen Xu Dr. Anna Gardberg Dr. Igor Mochalkin Dr. Theresa Johnson Dr. Ariele Viacava Follis Jared Head Dr. Federica Morandi 《ChemMedChem》2019,14(2):217-223
Bruton's tyrosine kinase (Btk) is an attractive target for the treatment of a wide array of B-cell malignancies and autoimmune diseases. Small-molecule covalent irreversible Btk inhibitors targeting Cys481 have been developed for the treatment of such diseases. In clinical trials, probe molecules are required in occupancy studies to measure the level of engagement of the protein by these covalent irreversible inhibitors. The result of this pharmacodynamic (PD) activity provides guidance for appropriate dosage selection to optimize inhibition of the drug target and correlation of target inhibition with disease treatment efficacy. This information is crucial for successful evaluation of drug candidates in clinical trials. Based on the pyridine carboxamide scaffold of a novel solvent-accessible pocket (SAP) series of covalent irreversible Btk inhibitors, we successfully developed a potent and selective affinity-based biotinylated probe 12 (2-[(4-{4-[5-(1-{5-[(3aS,4S,6aR)-2-oxo-hexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanamido}-3,6,9,12-tetraoxapentadecan-15-amido)pentanoyl]piperazine-1-carbonyl}phenyl)amino]-6-[1-(prop-2-enoyl)piperidin-4-yl]pyridine-3-carboxamide). Compound 12 has been used in Btk occupancy assays for preclinical studies to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon. 相似文献
28.
29.
30.
Ohne Zusammenfassung 相似文献