全文获取类型
收费全文 | 904篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
化学 | 443篇 |
晶体学 | 7篇 |
力学 | 39篇 |
数学 | 92篇 |
物理学 | 364篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 33篇 |
2017年 | 11篇 |
2016年 | 32篇 |
2015年 | 21篇 |
2014年 | 22篇 |
2013年 | 40篇 |
2012年 | 36篇 |
2011年 | 49篇 |
2010年 | 37篇 |
2009年 | 45篇 |
2008年 | 42篇 |
2007年 | 48篇 |
2006年 | 31篇 |
2005年 | 34篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 8篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 12篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1977年 | 11篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1933年 | 6篇 |
1929年 | 5篇 |
排序方式: 共有945条查询结果,搜索用时 196 毫秒
1.
Towards Polysulfuric Acids: The Hydrogentrisulfate Anion [HS3O10]− in A[HS3O10] (A=Na,K, Rb) 下载免费PDF全文
Lisa Verena Schindler Prof. Dr. Thorsten Klüner Prof. Dr. Mathias S. Wickleder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13865-13870
The reaction of Na2SO4 and K2SO4 with fuming sulfuric acid (65 % SO3) yielded colorless extremely sensitive crystals of Na[HS3O10] (monoclinic; P21/n (No. 14); Z=4; a=707.36(2), b=1378.56(4), c=848.10(3) pm; β=94.817(1)°; V=824.09(4) ? 106 pm3) and K[HS3O10] (orthorhombic; Pccn (No. 56); Z=4; a=1057.16(3), b=807.81(2), c=897.57(2) pm; V=766.51(3) ? 106 pm3). The analogous rubidium compound Rb[HS3O10] (orthorhombic; Pnma (No. 62); Z=4; a=891.43(3), b=1095.34(4), c=839.37(3) pm; V=819.58(5) ? 106 pm3) originates from the reaction of Rb2CO3 and SO3. All of the different structures contain the hitherto unknown anion [HS3O10]? and are stamped by strong hydrogen bonds linking the anions either to dimers or chains. Theoretical investigations by DFT methods give further insight in the structural characteristics of [HS3O10]?. The preparation of the [HS3O10]? anion can be seen as an important milestone on our way to the still elusive polysulfuric acids. 相似文献
2.
Corrigendum: Labeling and Selective Inactivation of Gram‐Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts 下载免费PDF全文
Dr. Anzhela Galstyan Dr. Desiree Block Dr. Silke Niemann Dr. Malte C. Grüner Prof.Dr. Stefania Abbruzzetti Michele Oneto Dr. Constantin G. Daniliuc Dr. Sven Hermann Prof.Dr. Cristiano Viappiani Prof.Dr. Michael Schäfers Prof.Dr. Bettina Löffler Priv.‐Doz.Dr. Cristian A. Strassert Dr. Andreas Faust 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9051-9051
3.
Niklas Rinn Dr. Jens P. Eußner Willy Kaschuba Dr. Xiulan Xie Prof. Dr. Stefanie Dehnen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):3094-3104
Reactions of R1SnCl3 (R1=CMe2CH2C(O)Me) with (SiMe3)2Se yield a series of organo‐functionalized tin selenide clusters, [(SnR1)2SeCl4] ( 1 ), [(SnR1)2Se2Cl2] ( 2 ), [(SnR1)3Se4Cl] ( 3 ), and [(SnR1)4Se6] ( 4 ), depending on the solvent and ratio of the reactants used. NMR experiments clearly suggest a stepwise formation of 1 through 4 by subsequent condensation steps with the concomitant release of Me3SiCl. Furthermore, addition of hydrazines to the keto‐functionalized clusters leads to the formation of hydrazone derivatives, [(Sn2(μ‐R3)(μ‐Se)Cl4] ( 5 , R3=[CMe2CH2CMe(NH)]2), [(SnR2)3Se4Cl] ( 6 , R2=CMe2CH2C(NNH2)Me), [(SnR4)3Se4][SnCl3] ( 7 , R4=CMe2CH2C(NNHPh)Me), [(SnR2)4Se6] ( 8 ), and [(SnR4)4Se6] ( 9 ). Upon treatment of 4 with [Cu(PPh3)3Cl] and excess (SiMe3)2Se, the cluster fragments to form [(R1Sn)2Se2(CuPPh3)2Se2] ( 10 ), the first discrete Sn/Se/Cu cluster compound reported in the literature. The derivatization reactions indicate fundamental differences between organotin sulfide and organotin selenide chemistry. 相似文献
4.
Dr. Aleksandra Markovic Luca Gerhards Dr. Pia Sander Dr. Carsten Dosche Prof. Dr. Thorsten Klüner Prof. Dr. Rüdiger Beckhaus Prof. Gunther Wittstock 《Chemphyschem》2020,21(22):2506-2514
Multinuclear transition metal complexes bridged by ligands with extended π-electronic systems show a variety of complex electronic transitions and electron transfer reactions. While a systematic understanding of the photochemistry and electrochemistry has been attained for binuclear complexes, much less is known about trinuclear complexes such as hexaphenyl-5,6,11,12,17,18-hexaazatrinaphthylene-tristitanocene [(Cp2Ti)3HATN(Ph)6]. The voltammogram of [(Cp2Ti)3HATN(Ph)6] shows six oxidation and three reduction waves. Solution spectra of [(Cp2Ti)3HATN(Ph)6] and of the electrochemically formed oxidation products show electronic transitions in the UV, visible and the NIR ranges. Density functional theory (DFT) and linear response time-dependent DFT show that the three formally titanium(II) centers transfer an electron to the HATN ligand in the ground state. The optically excited transitions occur exclusively between ligand-centered orbitals. The charged titanium centers only provide an electrostatic frame to the extended π-electronic system. Complete active self-consistent field (CASSCF) calculation on a structurally simplified model compound, which considers the multi-reference character imposed by the three titanium centers, can provide an interpretation of the experimentally observed temperature-dependent magnetic behavior of the different redox states of the title compound in full consistency with the interpretation of the electronic spectra. 相似文献
5.
We calculate the energy levels corresponding to the Roper resonance based on a two-flavor chiral effective Lagrangian for pions, nucleons, deltas, and the Roper resonance at the leading one-loop order. We show that the Roper mass can be extracted from these levels for lattice volumes of moderate size. 相似文献
6.
Dr. Jan Nekvinda Michael Kugler Dr. Josef Holub Dr. Suzan El Anwar Dr. Jiří Brynda Klára Pospíšilová Dr. Zdeňka Růžičková Dr. Pavlína Řezáčová Dr. Bohumír Grüner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16541-16553
Carbonic anhydrase IX (CA IX), a tumor-associated metalloenzyme, represents a validated target for cancer therapy and diagnostics. Herein, we report the inhibition properties of isomeric families of sulfonamidopropyl-dicarba-closo-dodecaboranes group(s) prepared using a new direct five-step synthesis from the corresponding parent cages. The protocol offers a reliable solution for synthesis of singly and doubly substituted dicarba-closo-dodecaboranes with a different geometric position of carbon atoms. The closo-compounds from the ortho- and meta-series were then degraded to corresponding 11-vertex dicarba-nido-undecaborate(1−) anions. All compounds show in vitro enzymatic activity against CA IX in the low nanomolar or subnanomolar range. This is accompanied by clear isomer dependence of the inhibition constant (Ki) and selectivity towards CA IX. Decreasing trends in Ki and selectivity index (SI) values are observed with increasing separation of the cage carbon atoms. Interactions of compounds with the active sites of CA IX were explored with X-ray crystallography, and eight high-resolution crystal structures uncovered the structural basis of inhibition potency and selectivity. 相似文献
7.
Rebecca Wiesner Holger Zagst Wenkui Lan Stewart Bigelow Peter Holper Göran Hübner Leila Josefsson Claire Lancaster Lili Lo Christopher Lößner Huixin Lu Christian Neusüß Carolin Rüttiger Johannes Schlecht Philipp Schürrle Alexander Selsam Debbie van der Burg Shao-Chun Wang Yunxiao Zhu Hermann Wätzig Cari Sänger-van de Griend 《Electrophoresis》2023,44(15-16):1247-1257
Capillary zone electrophoresis ultraviolet (CZE-UV) has become increasingly popular for the charge heterogeneity determination of mAbs and vaccines. The ε-aminocaproic acid (eACA) CZE-UV method has been used as a rapid platform method. However, in the last years, several issues have been observed, for example, loss in electrophoretic resolution or baseline drifts. Evaluating the role of eACA on the reported issues, various laboratories were requested to provide their routinely used eACA CZE-UV methods, and background electrolyte compositions. Although every laboratory claimed to use the He et al. eACA CZE-UV method, most methods actually deviate from He's. Subsequently, a detailed interlaboratory study was designed wherein two commercially available mAbs (Waters’ Mass Check Standard mAb [pI 7] and NISTmAb [pI 9]) were provided to each laboratory, along with two detailed eACA CZE-UV protocols for a short-end, high-speed, and a long-end, high-resolution method. Ten laboratories participated each using their own instruments, and commodities, showing excellence method performance (relative standard deviations [RSDs] of percent time-corrected main peak areas from 0.2% to 1.9%, and RSDs of migration times from 0.7% to 1.8% [n = 50 per laboratory], analysis times in some cases as short as 2.5 min). This study clarified that eACA is not the main reason for the abovementioned variations. 相似文献
8.
Dr. Sören Kirchgäßner Dr. Michael B. Braun Natascha Bartlick Dr. Cengiz Koç Dr. Christopher D. Reinkemeier Prof. Dr. Edward A. Lemke Prof. Dr. Thilo Stehle Prof. Dr. Dirk Schwarzer 《Angewandte Chemie (International ed. in English)》2023,62(12):e202215460
Lysine acetylation is a charge-neutralizing post-translational modification of proteins bound by bromodomains (Brds). A 1,2,4-triazole amino acid (ApmTri) was established as acetyllysine (Kac) mimic recruiting Brds of the BET family in contrast to glutamine commonly used for simulating this modification. Optimization of triazole substituents and side chain spacing allowed BET Brd recruitment to ApmTri-containing peptides with affinities similar to native substrates. Crystal structures of ApmTri-containing peptides in complex with two BET Brds revealed the binding mode which mirrored that of Kac ligands. ApmTri was genetically encoded and recombinant ApmTri-containing proteins co-enriched BRD3(2) from cellular lysates. This interaction was blocked by BET inhibitor JQ1. With genetically encoded ApmTri, biochemistry is now provided with a stable Kac mimic reflecting charge neutralization and Brd recruitment, allowing new investigations into BET proteins in vitro and in vivo. 相似文献
9.
10.
A simple and concise approach to the synthesis of coumarin-containing highly fluorescent asymmetric/symmetric 3,5-diaryl/heteroaryl-2,6-dicyanoaniline derivatives are reported. The compounds were synthesized through base catalyzed three-component one-pot synthesis reaction of 2-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)malononitrile, aliphatic, aromatic/heteroaromatic aldehydes, and malononitrile in solvent-free reaction medium, catalyzed by piperidine under microwave irradiation method. The reaction gave the novel, highly fluorescent coumarin-containing 3,5-disubstituted-2,6-dicyanoaniline derivatives in good yields at 300?W, 80?°C in 2?min. This method provides several advantages; such as shorter reaction time, environmental friendliness, simple workup procedure, lower energy consumption and, generally, good yields with high purity. In addition, the synthesized compounds are fluorescently active dyes even in day light, except for compounds including nitro substituent, and show maximum absorption wavelengths (λabs.max) in the visible region in DMSO at room temperature. Thermal properties of all the synthesized compounds were also evaluated with thermal gravimetric analysis for usability as optic dye. Optical and thermal screening studies of the compounds showed that the dyes have excellent photophysical and thermal stability properties. 相似文献