全文获取类型
收费全文 | 682篇 |
免费 | 44篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 727篇 |
出版年
2023年 | 15篇 |
2022年 | 10篇 |
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 17篇 |
2016年 | 35篇 |
2015年 | 24篇 |
2014年 | 32篇 |
2013年 | 49篇 |
2012年 | 48篇 |
2011年 | 49篇 |
2010年 | 38篇 |
2009年 | 33篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 17篇 |
2004年 | 17篇 |
2003年 | 9篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1975年 | 5篇 |
1973年 | 3篇 |
1969年 | 2篇 |
1948年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有727条查询结果,搜索用时 78 毫秒
1.
AbstractIn this day and age, it is widely argued that stakeholder engagement in water-related decision-making processes yields many benefits, including legitimacy, acceptance and trust. Key legal frameworks, such as the European Water Framework Directive and the Aarhus Convention, have spurred the emergence of formal forms of stakeholder engagement. On the other hand, many engagement processes are spontaneous and self-organized. This article investigates the strategies used in formal (government-led) and informal (bottom-up) engagement processes in search of a middle ground. To this end, case studies in the Netherlands, the United States, Uganda and Ethiopia are analyzed using the OECD’s stakeholder engagement checklist. We conclude with reflection on the ways forward to make formal and informal stakeholder engagement complementary. 相似文献
2.
In the recent past, society has become increasingly aware of the environmental impact of political and corporate action. Hence, several industrial sectors are currently undergoing a transition to more sustainable products and processes. Sustainable production processes for C2-C4 alcohols can help to decrease the environmental impacts of large downstream markets such as fuels and polymers. However, a reliable and consistent framework is needed for companies to further develop and commercialize these processes. Furthermore, standardized procedures for determining the sustainability of a process are essential in evaluating the environmental benefits. 相似文献
3.
4.
In traditional microbial biobutanol production, the solvent must be recovered during fermentation process for a sufficient space-time yield. Thermal separation is not feasible due to the boiling point of n-butanol. As an integrated and selective solid-liquid separation alternative, solvent impregnated resins (SIRs) were applied. Two polymeric resins were evaluated and an extractant screening was conducted. Vacuum application with vapor collection in fixed-bed column as bioreactor bypass was successfully implemented as butanol desorption step. In course of further increasing process economics, fermentation with renewable lignocellulosic substrates was conducted using Clostridium acetobutylicum. Utilization of SIR was shown to be a potential strategy for solvent removal from fermentation broth, while application of a bypass column allows for product removal and recovery at once. 相似文献
5.
Peptide Bioconjugates of Electron‐Poor Metallocenes: Synthesis,Characterization, and Anti‐Proliferative Activity 下载免费PDF全文
Marcus Maschke Jens Grohmann Claudia Nierhaus Dr. Max Lieb Prof. Dr. Nils Metzler‐Nolte 《Chembiochem : a European journal of chemical biology》2015,16(9):1333-1342
We report the synthesis of metallocene compounds Cp2M with two different electron‐withdrawing substituents on both cyclopentadienyl rings (hexafluoroacetone (HFA) and chlorobenzoyl ( 1 – 5 ); HFA and COOH ( 6 and 7 ), M=Fe or Ru). The COOH‐containing derivatives were used to synthesize peptide bioconjugates with enkephalin ( 8 and 9 ) and neurotensin ( 10 and 11 ) as well as fluorescein‐labeled neurotensin ( 12 ). All the molecules were fully characterized, including X‐ray structures for 6 and 7 . The physicochemical properties (lipophilicity and electrochemistry) and cytotoxicity on MCF‐7, HT‐29, and PT‐45 cancer cells were evaluated for selected compounds. Electrochemical investigation by cyclic voltammetry revealed that all bis‐substituted metallocenes are up to 300 mV harder to oxidize compared to the monosubstituted 2‐ferrocenylhexafluoropropan‐2‐ol (FcHFA: Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =214 mV; disubstituted derivatives: up to Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =512 mV; both vs. FcH0/+). For the bis‐substituted compounds, log P determinations by RP‐HPLC showed increased lipophilicity in comparison to the monosubstituted FcHFA and RcHFA. Cellular uptake was investigated by fluorescence microcopy, and this revealed endosomal entrapment for 12 . 相似文献
6.
Aryl Bis‐Sulfonamide Inhibitors of IspF from Arabidopsis thaliana and Plasmodium falciparum 下载免费PDF全文
Jonas Thelemann Dr. Boris Illarionov Dr. Konstantin Barylyuk Dr. Julie Geist Prof. Dr. Johannes Kirchmair Dr. Petra Schneider Lucile Anthore Katharina Root Dr. Nils Trapp Prof. Dr. Adelbert Bacher Dr. Matthias Witschel Prof. Dr. Renato Zenobi Prof. Dr. Markus Fischer Prof. Dr. Gisbert Schneider Prof. Dr. François Diederich 《ChemMedChem》2015,10(12):2090-2098
2‐Methylerythritol 2,4‐cyclodiphosphate synthase (IspF) is an essential enzyme for the biosynthesis of isoprenoid precursors in plants and many human pathogens. The protein is an attractive target for the development of anti‐infectives and herbicides. Using a photometric assay, a screen of 40 000 compounds on IspF from Arabidopsis thaliana afforded symmetrical aryl bis‐sulfonamides that inhibit IspF from A. thaliana (AtIspF) and Plasmodium falciparum (PfIspF) with IC50 values in the micromolar range. The ortho‐bis‐sulfonamide structural motif is essential for inhibitory activity. The best derivatives obtained by parallel synthesis showed IC50 values of 1.4 μm against PfIspF and 240 nm against AtIspF. Substantial herbicidal activity was observed at a dose of 2 kg ha?1. Molecular modeling studies served as the basis for an in silico search targeted at the discovery of novel, non‐symmetrical sulfonamide IspF inhibitors. The designed compounds were found to exhibit inhibitory activities in the double‐digit micromolar IC50 range. 相似文献
7.
Influence of the Multivalency of Ultrashort Arg‐Trp‐Based Antimicrobial Peptides (AMP) on Their Antibacterial Activity 下载免费PDF全文
Barbara C. Hoffknecht Dennis J. Worm Sandra Bobersky Pascal Prochnow Prof. Dr. Julia E. Bandow Prof. Dr. Nils Metzler‐Nolte 《ChemMedChem》2015,10(9):1564-1569
Peptide dendrimers are a class of molecules of high interest in the search for new antibiotics. We used microwave‐assisted, copper(I)‐catalyzed alkyne–azide cycloaddition (CuAAC; “click” chemistry) for the simple and versatile synthesis of a new class of multivalent antimicrobial peptides (AMPs) containing solely arginine and tryptophan residues. To investigate the influence of multivalency on antibacterial activity, short solid‐phase‐ synthesized azide‐modified Arg‐Trp‐containing peptides were “clicked” to three different alkyne‐modified benzene scaffolds to access scaffolds with one, two, or three peptides. The antibacterial activity of 15 new AMPs was investigated by minimal inhibitory concentration (MIC) assays on five different bacterial strains, including a multidrug‐resistant Staphylococcus aureus (MRSA) strain. With ultrashort (2–3 residues) peptides, a clear synergistic effect of the trivalent display was observed, whereas this effect was not apparent with longer peptides. The best candidates showed activities in the low‐micromolar range against Gram‐positive MRSA. Surprisingly, the best activity against Gram‐negative Acinetobacter baumannii was observed with an ultrashort dipeptide on the trivalent scaffold (MIC: 7.5 μM ). The hemolytic activity was explored for the three most active peptides. At concentrations ten times the MIC values, <1 % hemolysis of red blood cells was observed. 相似文献
8.
Nils C. Hildebrandt Julia Soldat Roland Marschall 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(17):2051-2057
The (111)‐layered perovskite materials Ba5Ta4O15, Ba5Ta2Nb2O15 and Ba5Nb4O15 are prepared with nanofiber morphology via electrospinning for the first time. The nanofibers are built up from small single crystals, with up to several micrometers length even after calcination. The formation mechanism is investigated in detail, revealing an intermediate formation of amorphous barium carbonate strengthening the nanofiber morphology for high temperature treatment. All nanofiber compounds are able to generate hydrogen without any co‐catalyst in photocatalytic reformation of methanol. After photodeposition of Rh‐Cr2O3 co‐catalysts, the nanofibers show better activity in overall water splitting compared to sol–gel‐derived powders. 相似文献
9.
Nils Hinrichsen 《Lipid Technology》2016,28(3-4):65-67
Since several years there has been a demand for food products free of palm oil, noticeable in the Western European market. Alternatives based on liquid oils, fully hydrogenated fats, and exotic fats like shea and sal etc., have been developed by the research groups of several specialty oils and fats suppliers. This article describes the advantages and disadvantages of those products and compares them to similar products based on palm oil. It is also discussed how reasonable the replacement of palm products would be, since sustainable and 3‐MCPD/glycidolester‐reduced palm based specialty oils are also available on the market. 相似文献
10.
Grinding processes can be optimized by simulating the influence of individual grains on process forces and surface topographies. However, the process results are significantly influenced by tool wear. Simulating this effect allows, e.g., the prediction of necessary tool changes when manufacturing large forming tools. Therefore, a new point-based approach for modeling arbitrarily shaped grains in different states of tool wear was developed. Based on a small amount of representative wear investigations, a flexible tool model was defined, which can be used for various tool shapes without further experiments. This model can be applied for grinding processes with varying engagement situations. 相似文献