全文获取类型
收费全文 | 9933篇 |
免费 | 555篇 |
国内免费 | 42篇 |
专业分类
化学 | 7343篇 |
晶体学 | 32篇 |
力学 | 167篇 |
数学 | 1533篇 |
物理学 | 1455篇 |
出版年
2023年 | 75篇 |
2022年 | 95篇 |
2021年 | 154篇 |
2020年 | 231篇 |
2019年 | 199篇 |
2018年 | 148篇 |
2017年 | 122篇 |
2016年 | 417篇 |
2015年 | 379篇 |
2014年 | 405篇 |
2013年 | 481篇 |
2012年 | 669篇 |
2011年 | 706篇 |
2010年 | 507篇 |
2009年 | 420篇 |
2008年 | 661篇 |
2007年 | 585篇 |
2006年 | 550篇 |
2005年 | 561篇 |
2004年 | 475篇 |
2003年 | 344篇 |
2002年 | 321篇 |
2001年 | 159篇 |
2000年 | 138篇 |
1999年 | 154篇 |
1998年 | 119篇 |
1997年 | 160篇 |
1996年 | 112篇 |
1995年 | 114篇 |
1994年 | 108篇 |
1993年 | 93篇 |
1992年 | 95篇 |
1991年 | 61篇 |
1990年 | 42篇 |
1989年 | 68篇 |
1988年 | 56篇 |
1987年 | 33篇 |
1986年 | 32篇 |
1985年 | 47篇 |
1984年 | 41篇 |
1983年 | 30篇 |
1982年 | 46篇 |
1981年 | 31篇 |
1980年 | 29篇 |
1979年 | 25篇 |
1978年 | 28篇 |
1977年 | 18篇 |
1975年 | 22篇 |
1973年 | 17篇 |
1968年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Sc3N@C68 is assigned to isomer Sc3N@C68:6140 on the grounds of relative energies, geometrical data, and its 13C NMR pattern. Sc3N@C68:6140 is an endohedral fullerene where each Sc atom is coordinated to the center of an equatorial pentalene unit. Static and dynamic computer simulations explain the different point groups observed in NMR and X-ray experiments. Computed and experimental 13C NMR pattern are in close agreement except for one low-intensity signal. The competing isomer Sc3N@C68:6275 is found to be 409 kJ/mol less stable and shows a different 13C NMR pattern. 相似文献
82.
83.
Nidetzky Bernd Griessler Richard Weinhausel Andreas Haltrich Dietmar Kulbe Klaus D. 《Applied biochemistry and biotechnology》1997,(1):159-172
Some important process properties of α-l,4-D-ghican phosphorylases isolated from the bacteriumCorynebacterium callunae and potato tubers (Solatium tuberosum) were compared. Apart from minor differences in their stability and specificity (represented by the maximum degree of maltodextrin
conversion) and a 10-fold higher affinity of the plant phosphorylase for maltodextrin (K
M of 1.3 g/L at 300 mM of orthophosphate), the performances of both enzymes in a continuous ultrafiltration membrane reactor
were almost identical. Product synthesis was carried out over a time course of 300–400 h in the presence or absence of auxiliary
pullulanase (increasing the accessibility of the glucan substrate for phosphorolytic attack up to 15–20%). The effect of varied
dilution rate and reaction temperature on the resulting productivities was quantitated, and a maximum operational temperature
of 40°C was identified. 相似文献
84.
Andreas Charalambous 《Analytica chimica acta》2005,547(1):53-58
This work is an investigation into the utility of bismuth-film electrodes (BiFEs) for the determination of indium in the presence of cadmium and lead by square wave anodic stripping voltammetry (SWASV). The purpose of this study was to demonstrate that, after judicious choice of the associated chemical and instrumental conditions, it is possible to achieve satisfactory separation of the relevant stripping peak and, thus, to determine simultaneously trace concentrations of cadmium, lead and indium. It was conclusively demonstrated that a BiFE performed better than the equivalent mercury-film electrode (MFE) in this particular application. 相似文献
85.
86.
87.
88.
Xiaoqiang Li Stefan Miltschitzky Andreas Grauer Veronika Michlov Burkhard Knig 《Tetrahedron》2006,62(52):12191-12196
The synthesis and peptide-binding properties of a Zn(II)nitrilotriacetate complex substituted with pyrimidine hydrazine amides are reported. The metal complex provides millimolar binding affinity in aqueous buffer to peptides bearing N-terminal His. The pyrimidine heterocycles intermolecularly interact with the bound peptide and quench the emission of nearby Trp residues by energy transfer. 相似文献
89.
Windberg E Hudecz F Marquardt A Sebestyén F Kiss A Bösze S Medzihradszky-Schweiger H Przybylski M 《Rapid communications in mass spectrometry : RCM》2002,16(9):834-839
An epitope motif, TX(1)TX(2)T, of mucin-2 glycoprotein was identified by means of a mucin-2-specific monoclonal antibody, mAb 994, raised against a synthetic mucin-derived 15-mer peptide conjugate. For determination of the epitope sequence recognised with highest affinity by mAb 994, a combinatorial approach was applied using the portioning-mixing technique excluding Cys. Antibody binding of libraries was most profound when Gln was at the X(1) position. Analytical characterisation of the TQTX(2)T library was conducted by amino acid analysis and matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) and electrospray ionisation Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometric methods. Control libraries were prepared by mixing 19 individual peptides corresponding to the TQTX(2)T sequence. Thus, mixtures of 6, 10 and 19 pentapeptides were analysed and compared with the combinatorial mixture. MALDI-TOFMS was able to detect only partially the components in the 6- and 10-member mixtures, but failed to characterise a more complex 19-member mixture. In contrast, ESI-FTICRMS resolved all mixtures of higher complexity and provided direct identification at monoisotopic resolution, such as for a peptide library containing 'isobaric' lysine and glutamine (Delta m = 0.0364 Da). The results of this study suggest that ESI-FTICRMS is a powerful tool for characterisation of combinatorial peptide libraries of higher complexity. 相似文献
90.
Andreas M. Küffner Miriam Linsenmeier Fulvio Grigolato Marc Prodan Remo Zuccarini Umberto Capasso Palmiero Lenka Faltova Paolo Arosio 《Chemical science》2021,12(12):4373
Biomolecular condensates are emerging as an efficient strategy developed by cells to control biochemical reactions in space and time by locally modifying composition and environment. Yet, local increase in protein concentration within these compartments could promote aberrant aggregation events, including the nucleation and growth of amyloid fibrils. Understanding protein stability within the crowded and heterogeneous environment of biological condensates is therefore crucial, not only when the aggregation-prone protein is the scaffold element of the condensates but also when proteins are recruited as client molecules within the compartments. Here, we investigate the partitioning and aggregation kinetics of the amyloidogenic peptide Abeta42 (Aβ-42), the peptide strongly associated with Alzheimer''s disease, recruited into condensates based on low complexity domains (LCDs) derived from the DEAD-box proteins Laf1, Dbp1 and Ddx4, which are associated with biological membraneless organelles. We show that interactions between Aβ-42 and the scaffold proteins promote sequestration and local increase of the peptide concentration within the condensates. Yet, heterotypic interactions within the condensates inhibit the formation of amyloid fibrils. These results demonstrate that biomolecular condensates could sequester aggregation-prone proteins and prevent aberrant aggregation events, despite the local increase in their concentration. Biomolecular condensates could therefore work not only as hot-spots of protein aggregation but also as protective reservoirs, since the heterogenous composition of the condensates could prevent the formation of ordered fibrillar aggregates.Biomolecular condensates sequester an aggregation-prone peptide and prevent its aggregation, showing that heterotypic interactions within the condensates can prevent the formation of amyloid fibrils, despite the local increase in concentration. 相似文献