全文获取类型
收费全文 | 431篇 |
免费 | 30篇 |
专业分类
电工技术 | 2篇 |
综合类 | 2篇 |
化学工业 | 170篇 |
金属工艺 | 6篇 |
机械仪表 | 10篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 64篇 |
水利工程 | 2篇 |
无线电 | 14篇 |
一般工业技术 | 64篇 |
冶金工业 | 39篇 |
原子能技术 | 7篇 |
自动化技术 | 54篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 23篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 9篇 |
2015年 | 18篇 |
2014年 | 28篇 |
2013年 | 37篇 |
2012年 | 33篇 |
2011年 | 34篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 14篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有461条查询结果,搜索用时 15 毫秒
451.
452.
453.
Pahlow M Müller D Tesche M Eichler H Feingold G Eberhard WL Cheng YF 《Applied optics》2006,45(28):7429-7442
Simulation studies were carried out with regard to the feasibility of using combined observations from sunphotometer (SPM) and lidar for microphysical characterization of aerosol particles, i.e., the retrieval of effective radius, volume, and surface-area concentrations. It was shown that for single, homogeneous aerosol layers, the aerosol parameters can be retrieved with an average accuracy of 30% for a wide range of particle size distributions. Based on the simulations, an instrument combination consisting of a lidar that measures particle backscattering at 355 and 1574 nm, and a SPM that measures at three to four channels in the range from 340 to 1020 nm is a promising tool for aerosol characterization. The inversion algorithm has been tested for a set of experimental data. The comparison with the particle size distribution parameters, measured with in situ instrumentation at the lidar site, showed good agreement. 相似文献
454.
Chen Lyu Lili Wang Birgit Stadlbauer Alexander Buchner Heike Pohla 《International journal of molecular sciences》2022,23(24)
Emerging evidence from research or clinical studies reported that ABCG2 (ATP-binding cassette sub-family G member 2) interrelates with multidrug resistance (MDR) development in cancers. However, no comprehensive pan-cancer analysis is available at present. Therefore, we explore multiple databases, such as TCGA to investigate the potential therapeutic roles of ABCG2 across 33 different tumors. ABCG2 is expressed on a lower level in most cancers and shows a protective effect. For example, a lower expression level of ABCG2 was detrimental to the survival of adrenocortical carcinoma (TCGA-ACC), glioblastoma multiforme (GBM), and kidney renal clear cell carcinoma (KIRC) patients. Distinct associations exist between ABCG2 expression and stemness scores, microenvironmental scores, microsatellite instability (MSI), and tumor mutational burden (TMB) of tumor patients. We observed a significant positive correlation between the ABCG2 mutation site and prognosis in uterine corpus endometrial carcinoma (UCEC) patients. Moreover, transmembrane transporter activity and hormone biosynthetic-associated functions were found to be involved in the functionality of ABCG2 and its related genes. The cDNAs of cancer cell lines were collected to detect exon mutation sequences and to analyze ABCG2 mRNA expression. The mRNA expression level of ABCG2 showed a significant difference among spheres and drug-resistant cancer cell lines compared with their corresponding adherent cancer cell lines in six types of cancer. This pan-cancer study provides, for the first time, a comprehensive understanding of the multifunctionality of ABCG2 and unveils further details of the potential therapeutic role of ABCG2 in pan-cancer. 相似文献
455.
Dr. Simon J. A. Wiedemeyer Dr. Guojie Wu Dr. T. L. Phuong Pham Heike Lang-Henkel Benjamin Perez Urzua Prof. James C Whisstock Dr. Ruby H. P. Law Prof. Torsten Steinmetzer 《ChemMedChem》2023,18(6):e202200632
Two series of macrocyclic plasmin inhibitors with a C-terminal benzylamine group were synthesized. The substitution of the N-terminal phenylsulfonyl group of a previously described inhibitor provided two analogues with sub-nanomolar inhibition constants. Both compounds possess a high selectivity against all other tested trypsin-like serine proteases. Furthermore, a new approach was used to selectively introduce asymmetric linker segments. Two of these compounds inhibit plasmin with Ki values close to 2 nM. For the first time, four crystal structures of these macrocyclic inhibitors could be determined in complex with a Ser195Ala microplasmin mutant. The macrocyclic core segment of the inhibitors binds to the open active site of plasmin without any steric hindrance. This binding mode is incompatible with other trypsin-like serine proteases containing a sterically demanding 99-hairpin loop. The crystal structures obtained experimentally explain the excellent selectivity of this inhibitor type as previously hypothesized. 相似文献
456.
Ass. Prof. Tien Dinh Vu Associate Prof. Rangabhashiyam Selvasembian Dr.-Ing. Ivana Mutavdžin Dr.-Ing. Elena Horosanskaia Prof. Heike Lorenz Prof. Andreas Seidel-Morgenstern 《化学,工程师,技术》2023,95(11):1851-1857
The flavonoid rutin is present in significant amounts in the flower buds of Sophora japonica L. It offers numerous desired pharmacological effects. Under certain extraction conditions quercetin is found as a hydrolysis product which needs to be separated from rutin. This paper describes the application of liquid chromatography to solve this task. Based on the determination of adsorption equilibrium constants and column efficiencies, the productivity of the separation process is estimated, and scale-up considerations are presented. A comparison with alternatively directly crystallizing rutin from raw extracts is also reported. 相似文献
457.
Heike Lindauer Peter Czerney Ulrich-W. Grummt 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):216-221
A series of new acidochromic dyes absorbing in the NIR spectral region (up to 900 nm) has been synthesized with a systematic variation of the underlying nonsymmetric pyrylium trimethinium acridine structure. The dyes exhibit pKa-values between 5.7 and 6.7. Semiempirical MO-calculations were performed to elucidate the essentials of the chromophores. 相似文献
458.
Dr. Patrick Werner Dr. Patrick Schuenke Dr. Oxana Krylova Heike Nikolenko Prof. Dr. Matthias Taupitz Dr. Leif Schröder 《ChemMedChem》2022,17(13):e202100764
Glycosaminoglycans (GAGs) are highly negatively charged macromolecules with a large cation binding capacity, but their interaction potential with exogeneous Gd3+ ions is under-investigated. These might be released from chelates used as Gadolinium-based contrast agents (GBCAs) for clinical MR imaging due to transmetallation with endogenous cations like Zn2+. Recent studies have quantified how an endogenous GAG sequesters released Gd3+ ions and impacts the thermodynamic and kinetic stability of some GBCAs. In this study, we investigate and compare the chelation ability of two important GAGs (heparin and chondroitin sulfate), as well as the homopolysaccharides dextran and dextran sulfate that are used as models for alternative macromolecular chelators. Our combined approach of MRI-based relaxometry and isothermal titration calorimetry shows that the chelation process of Gd3+ into GAGs is not just a long-range electrostatic interaction as proposed for the Manning model, but presumably a site-specific binding. Furthermore, our results highlight the crucial role of sulfate groups in this process and indicate that the potential of a specific GAG to engage in this mechanism increases with its degree of sulfation. The transchelation of Gd3+ ions from GBCAs to sulfated GAGs should thus be considered as one possible explanation for the observed long-term deposition of Gd3+ in vivo and related observations of long-term signal enhancements on T1-weighted MR images. 相似文献
459.
Dr. Isabel V. L. Wilkinson Dr. Gabriel Castro-Falcón Dr. Maria C. Roda-Serrat Dr. Trevor N. Purdy Jan Straetener Melanie M. Brauny Prof. Dr. Lisa Maier Prof. Dr. Heike Brötz-Oesterhelt Prof. Dr. Lars P. Christensen Prof. Dr. Stephan A. Sieber Dr. Chambers C. Hughes 《Chembiochem : a European journal of chemical biology》2023,24(5):e202200455
The blue biliprotein phycocyanin, produced by photo-autotrophic cyanobacteria including spirulina (Arthrospira) and marketed as a natural food supplement or “nutraceutical,” is reported to have anti-inflammatory, antioxidant, immunomodulatory, and anticancer activity. These diverse biological activities have been specifically attributed to the phycocyanin chromophore, phycocyanobilin (PCB). However, the mechanism of action of PCB and the molecular targets responsible for the beneficial properties of PCB are not well understood. We have developed a procedure to rapidly cleave the PCB pigment from phycocyanin by ethanolysis and then characterized it as an electrophilic natural product that interacts covalently with thiol nucleophiles but lacks any appreciable cytotoxicity or antibacterial activity against common pathogens and gut microbes. We then designed alkyne-bearing PCB probes for use in chemical proteomics target deconvolution studies. Target identification and validation revealed the cysteine protease legumain (also known as asparaginyl endopeptidase, AEP) to be a target of PCB. Inhibition of this target may account for PCB's diverse reported biological activities. 相似文献
460.
Machine learning algorithms are widely applied to create powerful prediction models. With increasingly complex models, humans' ability to understand the decision function (that maps from a high-dimensional input space) is quickly exceeded. To explain a model's decisions, black-box methods have been proposed that provide either non-linear maps of the global topology of the decision boundary, or samples that allow approximating it locally. The former loses information about distances in input space, while the latter only provides statements about given samples, but lacks a focus on the underlying model for precise ‘What-If'-reasoning. In this paper, we integrate both approaches and propose an interactive exploration method using local linear maps of the decision space. We create the maps on high-dimensional hyperplanes—2D-slices of the high-dimensional parameter space—based on statistical and personal feature mutability and guided by feature importance. We complement the proposed workflow with established model inspection techniques to provide orientation and guidance. We demonstrate our approach on real-world datasets and illustrate that it allows identification of instance-based decision boundary structures and can answer multi-dimensional ‘What-If'-questions, thereby identifying counterfactual scenarios visually. 相似文献