全文获取类型
收费全文 | 512篇 |
免费 | 52篇 |
国内免费 | 1篇 |
专业分类
化学 | 487篇 |
力学 | 4篇 |
数学 | 41篇 |
物理学 | 33篇 |
出版年
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 29篇 |
2019年 | 29篇 |
2018年 | 14篇 |
2017年 | 5篇 |
2016年 | 27篇 |
2015年 | 21篇 |
2014年 | 45篇 |
2013年 | 22篇 |
2012年 | 51篇 |
2011年 | 42篇 |
2010年 | 34篇 |
2009年 | 26篇 |
2008年 | 33篇 |
2007年 | 25篇 |
2006年 | 25篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有565条查询结果,搜索用时 15 毫秒
81.
82.
Advances in Iodine(III)‐Mediated Halogenations: A Versatile Tool to Explore New Reactivities and Selectivities
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Andreas M. Arnold Anna Ulmer Dr. Tanja Gulder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(26):8728-8739
Within the repertoire of organic chemical transformations, the halogenation of substrates is among the most versatile, reliable, and broadly applicable reactions. Although a multitude of different methods are known today, there is still a huge demand for novel and, in particular, catalytic halogenation methods that exhibit new reactivities and selectivities. The class of hypervalent iodanes meets exactly these needs and thus offers a great opportunity to fuel this highly desirable direction within the field of halogenation chemistry. This Concept gives a short overview of recent examples focusing on selective and/or mechanistically unusual halogenations. 相似文献
83.
Site‐Selective Disulfide Modification of Proteins: Expanding Diversity beyond the Proteome
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Seah Ling Kuan Dr. Tao Wang Prof. Dr. Tanja Weil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17112-17129
The synthetic transformation of polypeptides with molecular accuracy holds great promise for providing functional and structural diversity beyond the proteome. Consequently, the last decade has seen an exponential growth of site‐directed chemistry to install additional features into peptides and proteins even inside living cells. The disulfide rebridging strategy has emerged as a powerful tool for site‐selective modifications since most proteins contain disulfide bonds. In this Review, we present the chemical design, advantages and limitations of the disulfide rebridging reagents, while summarizing their relevance for synthetic customization of functional protein bioconjugates, as well as the resultant impact and advancement for biomedical applications. 相似文献
84.
Bringmann G Haagen Y Gulder TA Gulder T Heide L 《The Journal of organic chemistry》2007,72(11):4198-4204
Streptomyces cinnamonensis DSM 1042 produces the polyketide-isoprenoid compound furanonaphthoquinone I (FNQ I) and isoprenylated phenazines, predominantly endophenazine A. However, the recently identified biosynthetic gene cluster for these compounds only contains a single gene for a mevalonate pathway enzyme, that is, a putative mevalonate kinase gene. This is in strong contrast to all Streptomyces strains examined so far, where all six genes encoding the mevalonate pathway enzymes are clustered in a single operon of 6.8 kb and, thus, raised the question about the biosynthetic origin of the isoprenoid moieties of FNQ I and endophenazine A. In this study, we investigated the incorporation of [13C2]acetate and [2-13C]glycerol into FNQ I and endophenazine A. The results unequivocally prove that the isoprenoid building blocks of both compounds are predominantly formed via the mevalonate pathway (approximately 80%) but that the MEP pathway (approximately 20%) contributes to the biosynthesis of these molecules, too. In actinomycetes, this is the first experimentally proven example of the utilization of both biosynthetic routes for the formation of one single secondary metabolite. The incorporation pattern of [2-13C]glycerol was consistent with a "reverse" prenyl transfer, that is, with the formation of a C-C bond from C-3 of GPP to the polyketide nucleus of FNQ I. 相似文献
85.
86.
87.
Alejandro Saenz Tanja Asthalter Wolf Weyrich 《International journal of quantum chemistry》1997,65(3):213-223
For the first time, an analytical and efficient algorithm for the evaluation of spherically averaged reciprocal form factors B(s)=〈B( s )〉Ω using Gauss-type basis functions is presented. The spherically averaged Compton profile is available by Fourier transformation of the reciprocal form factor. The algorithm has been successfully implemented in connection with the quantum chemistry codes GAMESS and CRYSTAL92, which perform Hartree–Fock calculations for molecules and solids. In addition, an analytical algorithm for the direct evaluation of spherically averaged Compton profiles and the moments 〈pν〉 (ν≥−1) via the momentum density is proposed for Gauss-type basis functions. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65 : 213–223, 1997 相似文献
88.
Pr(BO2)3 and PrCl(BO2)2: Two Praseodymium meta‐Borates in Comparison Single‐crystalline PrCl(BO2)2 can be obtained by the reaction of praseodymium, Pr6O11 and PrCl3 with a small excess of B2O3 in evacuated silica tubes after seven days at 850 °C. If NaCl is additionally used as flux, single crystals of Pr(BO2)3 dominate the main product. Both praseodymium(III) meta‐borates are air and water stable. The crystals of PrCl(BO2)2 emerge as long, thin, pale green needles which tend to severe twinning due to their fibrous habit. The crystal structure (triclinic, P1¯; a = 420.56(4), b = 655.42(7), c = 808.34(8) pm, α = 82.361(8), β = 89.173(9), γ = 71.980(7)°, Z = 2) exhibits zigzag chains {[(B1)ot1/1Oe2/2(B2)Ot1/1Oe2/2]2−} (≡ {[BO2]−}) of corner‐linked [BO3]3− triangles with syndiotactic orientation of the terminal oxygen atoms which are running parallel to the [100] direction. The Pr3+ cations are surrounded by three Cl− and seven O2− anions with the shape of a tetracapped trigonal prism. The green, transparent crystals of Pr(BO2)3 (monoclinic, C2/c; a= 984.98(9), b = 809.57(8), c = 641.02(6) pm, β = 126.783(9)°, Z = 4) appear either lath‐shaped or rather spherical. In the crystal structure the B3+ cations reside both in trigonal planar as well as in tetrahedral coordination of oxygen atoms. Both types of borate polyhedra ([BO3]3− and [BO4]5−) are linked via corners to form chains of the composition {[(B2)‐Ot1/1Oe2/2(B1)Oe4/2(B2)Ot1/1Oe2/2]3−} (≡ {[BO2]−}) which run parallel [101]. The coordination sphere of the Pr3+ cations consists of ten oxide anions which build up a bicapped square antiprism. 相似文献
89.
Klaus Albert Markus Dachtler Tobias Glaser Heidi Hndel Tanja Lacker Gtz Schlotterbeck Sabine Strohschein Li-Hong Tseng Ulrich Braumann 《Journal of separation science》1999,22(3):135-143
The hyphenation of chromatographic separation techniques with NMR spectroscopy is one of the most powerful and time-saving methods for the separation and structural elucidation of unknown compounds and molecular compositions of mixtures. Most of the routinely used NMR flow-cells have detection volumes between 40–180 μL for conventional separations with analytical columns, and the newest designs employ detection volumes in the order of 200 nL for capillary separations. The low flow rates used in capillary chromatography permit the use of deuterated solvents. Unequivocal structural assignment of unknown chromatographic peaks is possible by two-dimensional stopped-flow capillary HPLC-NMR experiments. 相似文献
90.
Tobat P.I. Saragi Christoph Schmidt Tanja Weis Arno Ehresmann 《Journal of magnetism and magnetic materials》2009,321(14):2204-2209
The surface and interface morphology and magnetization characteristics of Co70Fe30 thin films deposited on bare glass and p-Si/SiO2 substrates and on conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) thin films on such substrates have been studied by atomic force microscopy and magneto-optic Kerr effect. It was found that the average absolute magnitude of the coercive field of Co70Fe30 correlates with the roughness of the underlayer prior to Co70Fe30 deposition. P3HT deposited on p-Si/SiO2 substrates possesses an increased surface roughness as compared to the p-Si/SiO2 surface, but displays a decreased surface roughness as compared to the one of a bare glass substrate. 相似文献