全文获取类型
收费全文 | 278篇 |
免费 | 35篇 |
专业分类
化学 | 264篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 30篇 |
物理学 | 15篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2017年 | 2篇 |
2016年 | 26篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 25篇 |
2012年 | 22篇 |
2011年 | 25篇 |
2010年 | 23篇 |
2009年 | 8篇 |
2008年 | 28篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1985年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1964年 | 1篇 |
排序方式: 共有313条查询结果,搜索用时 187 毫秒
211.
Dr. Slava Ziegler Dr. Verena Pries Dr. Christian Hedberg Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2013,52(10):2744-2792
Identification and confirmation of bioactive small‐molecule targets is a crucial, often decisive step both in academic and pharmaceutical research. Through the development and availability of several new experimental techniques, target identification is, in principle, feasible, and the number of successful examples steadily grows. However, a generic methodology that can successfully be applied in the majority of the cases has not yet been established. Herein we summarize current methods for target identification of small molecules, primarily for a chemistry audience but also the biological community, for example, the chemist or biologist attempting to identify the target of a given bioactive compound. We describe the most frequently employed experimental approaches for target identification and provide several representative examples illustrating the state‐of‐the‐art. Among the techniques currently available, protein affinity isolation using suitable small‐molecule probes (pulldown) and subsequent mass spectrometric analysis of the isolated proteins appears to be most powerful and most frequently applied. To provide guidance for rapid entry into the field and based on our own experience we propose a typical workflow for target identification, which centers on the application of chemical proteomics as the key step to generate hypotheses for potential target proteins. 相似文献
212.
Kristof Tappertzhofen Verena V. Metz Mario Hubo Matthias Barz Rolf Postina Helmut Jonuleit Rudolf Zentel 《Macromolecular bioscience》2013,13(2):203-214
Herein the synthesis of antibody–polymer conjugates, with a quite narrow dispersity based on the polymer HPMA, are reported. These conjugates are synthesized by coupling antibodies to maleimide‐functionalized poly(N‐(2‐hydroxypropyl)‐methacrylamide) (poly‐HPMA) copolymers derived through reversible addition‐fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate via the intermediate step of an activated ester polymer. We develop a protocol that allows the attachment of two different model antibodies, monoclonal anti‐RAGE (receptor for advanced glycation end‐products) antibody, and polyclonal human immunoglobulin (huIgG). Modification of the antibody and conjugation is monitored by SDS‐PAGE electrophoresis. Preserved affinity is demonstrated by Western Blott and cell‐uptake analysis, for example, to cells of the immune system.
213.
Meister H Landwehr M Pyschny V Grugel L Walger M 《The Journal of the Acoustical Society of America》2011,129(5):EL204-EL209
The corruption of intonation contours has detrimental effects on sentence-based speech recognition in normal-hearing listeners Binns and Culling [(2007). J. Acoust. Soc. Am. 122, 1765-1776]. This paper examines whether this finding also applies to cochlear implant (CI) recipients. The subjects' F0-discrimination and speech perception in the presence of noise were measured, using sentences with regular and inverted F0-contours. The results revealed that speech recognition for regular contours was significantly better than for inverted contours. This difference was related to the subjects' F0-discrimination providing further evidence that the perception of intonation patterns is important for the CI-mediated speech recognition in noise. 相似文献
214.
215.
Helmut Rosemeyer Verena Mokrosch Anup Jawalekar Eva‐Maria Becker Frank Seela 《Helvetica chimica acta》2004,87(2):536-553
The minihairpin 5′‐d(GCGAAGC)‐3′ ( 1 ) was modified either in the loop region, in the base‐paired stem, or at the 5′‐terminus by incorporation of base‐modified nucleosides. The thermal melting was correlated to the structural changes induced by the various donor‐acceptor properties of the nucleosides. Overhanging nonpaired nucleosides at the 5′‐terminus stabilized the hairpin, while a reverse of the dG3?dA5 sheared base pair to dA3?dG5 severely affected the stability. The combination of the minihairpin 5′‐d(GCGAAGC)‐3′ ( 1 ) and the thrombin‐binding aptamer 5′‐d(GGTTGGTGTGGTTGG)‐3′ ( 2 (= 46 )) resulted in the new construct 5′‐d(GGTTGGGCGAAGC GGTTGG)‐3′ ( 43 ) arising by replacement of the 5′‐d(TGT)‐3′ loop of 2 by the minihairpin. The fused oligonucleotide 43 exhibits a two‐phase thermal transition indicating the presence of the two unaltered moieties. According to slight changes of the Tm values of the construct 43 as compared to the separate units 1 and 2 , cooperative distorsions are discussed. 相似文献
216.
Gumann S Nestle N Liebau-Kunzmann V Riedel R 《Solid state nuclear magnetic resonance》2007,31(2):82-90
Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20 with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 degrees C in argon (DeltaT=200 degrees C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 degrees C and formed LiSi(2)N(3), graphite and silicon carbide as crystalline phases at higher temperatures. (7)Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li(+) species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 degrees C. 相似文献
217.
218.
Looser V Langenegger SM Häner R Hartig JS 《Chemical communications (Cambridge, England)》2007,(42):4357-4359
Highly active variants of minimal hammerhead ribozymes are generated by the replacement of substantial parts of stem-loop structures with pyrene building blocks. 相似文献
219.
Hebben N Himmel HJ Eickerling G Herrmann C Reiher M Herz V Presnitz M Scherer W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10078-10087
In this article we analyze in detail the electronic properties of the D(3h)-symmetric tris(ethylene) complexes of nickel, palladium, and platinum ([M(C(2)H(4))(3)] M=Ni, Pd, Pt). In the case of [Pd(C(2)H(4))(3)] the analysis is based on new experimental IR and Raman spectra for the matrix-isolated molecules and in all cases on the results of quantum-chemical (DFT) calculations. The experimental spectra collected for [Pd(C(2)H(4))(3)] provide evidence for several previously unobserved vibrational modes, including the in-phase and out-of-phase nu(C-C) and delta(CH(2)) modes, and the in-phase nu(M-C) mode. Special consideration is given to possible inter-ligand interactions. The interaction force constant f(CC,CC) between two C(2)H(4) ligands can be directly estimated from the spectra, and its very small value (0.002 N m(-1)) indicates the absence of any significant inter-ligand interaction. An analysis of the topology of the theoretical electron density distribution, rho(r), and the corresponding Laplacian, nabla(2)rho(r), for [Pd(C(2)H(4))(3)] and its lighter and heavier homologues [Ni(C(2)H(4))(3)] and [Pt(C(2)H(4))(3)], respectively, is in full agreement with the conclusions drawn from the experimental results. The combined experimental and quantum-chemical results provide detailed insights in the electronic properties of these prototypical ethylene complexes. 相似文献
220.
Single crystals of the new compounds TM2Cu3Ga8 (TM=V, Mo, W) were synthesised from the elements. Structure determinations of the isotypic compounds (cI104, space group , Z=8; Mo2Cu3Ga8: a=11.9171(10) Å, 613 refl., 23 param., R1(F)=0.022, wR2(F2)=0.047; W2Cu3Ga8: 11.9248(8) Å, 346 refl., 23 param., R1(F)=0.048, wR2(F2)=0.086; V2Cu3Ga8: 11.7861(14) Å, 374 refl., 24 param., R1(F)=0.033, wR2(F2)=0.081) showed a new cubic structure type which can be classified as an ordered defect variant of a bcc packing with a′=4a: [(TM)2(Cu)3(□)3][Ga8]. The coordination polyhedra of the transition metals consist of Ga8-cubes with 3 sides capped by Cu leading to coordination number 11. The arrangement of the TMGa8Cu3-polyhedra is in a way they form itself a 3-fold capped cube. All compositions were confirmed by EDX measurements. 相似文献