全文获取类型
收费全文 | 3281篇 |
免费 | 161篇 |
国内免费 | 3篇 |
专业分类
化学 | 2205篇 |
晶体学 | 38篇 |
力学 | 121篇 |
数学 | 476篇 |
物理学 | 605篇 |
出版年
2023年 | 33篇 |
2022年 | 33篇 |
2021年 | 38篇 |
2020年 | 54篇 |
2019年 | 51篇 |
2018年 | 65篇 |
2017年 | 55篇 |
2016年 | 108篇 |
2015年 | 95篇 |
2014年 | 106篇 |
2013年 | 195篇 |
2012年 | 263篇 |
2011年 | 284篇 |
2010年 | 130篇 |
2009年 | 114篇 |
2008年 | 226篇 |
2007年 | 190篇 |
2006年 | 179篇 |
2005年 | 173篇 |
2004年 | 149篇 |
2003年 | 117篇 |
2002年 | 81篇 |
2001年 | 40篇 |
2000年 | 43篇 |
1999年 | 33篇 |
1998年 | 31篇 |
1997年 | 22篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 29篇 |
1991年 | 30篇 |
1990年 | 30篇 |
1989年 | 26篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1985年 | 22篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 13篇 |
1978年 | 20篇 |
1977年 | 16篇 |
1976年 | 15篇 |
1975年 | 14篇 |
1974年 | 11篇 |
1973年 | 14篇 |
排序方式: 共有3445条查询结果,搜索用时 15 毫秒
61.
Cremer GA Bureaud N Lelièvre D Piller V Piller F Delmas A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(24):6353-6360
Our goal was to develop mimics of MUC1, highly immunogenic to induce an efficient immune response against the tumor-associated form of MUC1, and sufficiently different from the natural antigen to bypass the tolerance barrier in humans. With the aim of obtaining a well-defined peptide construct as a means of evoking the precise immune responses required in immunotherapy, we synthesized artificial mimics of the MUC1 protein composed of two MUC1 repeat units of inverse orientation and a universal T-helper epitope. To synthesize these heteromeric peptide constructs, we followed a convergent approach using chemoselective ligation based on oxime chemistry. A stem peptide was first synthesized bearing two orthogonally masked aldehydes. After successive deprotection, two oxime bonds can be specifically generated. The proposed strategy proved to be concise and robust, and allowed the synthesis of the tri-branched protein in a very satisfactory yield. The different constructs were tested for their ability to generate antibodies able to recognize the MUC1 protein. 相似文献
62.
63.
Data on the mean multiplicity of
- produced in minimum bias proton-proton, proton-neutron and proton-nucleus interactions as well as central nucleus-nucleus collisions at momenta of 1.4–400 GeV/c per nucleon have been compiled and studied. The results for neutron-neutron and nucleon-nucleon interactions were then constructed. The dependence of the mean pion multiplicity in proton-nucleus interactions and central collisions of identical nuclei are studied as a function of the collision energy and the nucleus mass number. The number of produced pions per participant nucleon in central collisions of identical nuclei is found to be independent of the number of participants at a fixed incident momentum per nucleon. The mean multiplicity of negatively charged hadrons per participant nucleon for central nucleus-nucleus collisions is lower by about 0.12 than the corresponding multiplicity for nucleon-nucleon interactions atp
LAB
15 A·GeV/c, whereas the result at 200 A·GeV/c is above the corresponding nucleon-nucleon multiplicity. This may indicate change of the collision dynamics at high energy. 相似文献
64.
Dominique Lorcy Leonardo Mattiello Cyril Poriel Joëlle Rault-Berthelot 《Journal of Electroanalytical Chemistry》2002,530(1-2)
New three-dimensional copolymers containing 9,9′-spirobifluorenyl-ethylene units were prepared by anodic oxidation of 9,9′-spirobifluorenes 2-mono- or 2,7′-disubstituted by a dithiafulvenyl unit. The synthesis, physicochemical properties and electrochemistry of both monomers and derived oligomers and polymers are reported. 相似文献
65.
Jiří Kohout Mária Kabešová Prof. Dipl.-Ing. Dr. Ján Gažo 《Monatshefte für Chemie / Chemical Monthly》1977,108(5):1011-1018
The infrared spectra of thiocyanato-copper(II) complexes of the type Cu(NCS)2
L
2 with all isomeric picolines and lutidines (L) as well as those of the type Cu(NCS)2
L
3 withL=3- and 4-picoline, 3,4- and 3,5-lutidine were measured. The behaviour of the (CN) stretching vibrations of the Cu(NCS)2
L
2 complexes led to conclusions on the different kind of coordination of the NCS groups in dependence on the ligandL. The mutually conditioned strength of the Cu–NCS and Cu–N(L) bonds in the equatorial plane, especially in the presence of ligandsL with the steric effect, was determined from the frequency shift of the Cu–NCS and Cu–N(L) stretching vibrations with regard to the vibrations for Cu(NCS)2(pyridine)2.
Mit 1 Abbildung 相似文献
Mit 1 Abbildung 相似文献
66.
Robin Zuluaga Jean-Luc Putaux Adriana Restrepo Iñaki Mondragon Piedad Gañán 《Cellulose (London, England)》2007,14(6):585-592
Cellulose microfibrils have been prepared from banana rachis using a combination of chemical and mechanical treatments. The
morphology and structure of the samples were characterized using transmission electron microscopy, atomic force microscopy,
and X-ray diffraction. Fourier-transformed infrared spectroscopy (FTIR) was used to characterize the chemical modifications
of the samples after each treatment. Suspensions of bundled or individualized 5-nm-wide microfibrils were obtained after homogenization
(PH) whereas an organosolv (PO) treatment resulted in shorter aggregates of parallel cellulose microcrystallites. The sharper
rings in the X-ray diffraction pattern of the PO-treated sample suggest a higher crystallinity due to a more efficient removal
of hemicelluloses and dissolution of amorphous zones by the acid treatment. Both microfibrils and microcrystals prepared by
both methods can be used as reinforcing filler in nanocomposite materials. 相似文献
67.
68.
J. Kohout M. Quastlerová-Hvastijová J. Gažo 《Monatshefte für Chemie / Chemical Monthly》1973,104(3):779-783
Zusammenfassung Die Ligandenfeldspektren der Komplexe des Typs Cu(NCO)2
L
2 (L=Ligand der Chinolin- bzw. Isochinolingruppe) im festen Zustand wurden aufgenommen. Das Spektrum des Komplexes Cu(NCO)2(Chin)2 weist eine einzige Bande auf und deutet auf eine pseudooktaedrische Struktur. Die Spektren der übrigen Komplexe enthalten hingegen neben den Hauptbanden auch Schultern bzw. ist die anwesende Bande zusammengesetzt, so daß diese Spektren mit einer planaren Struktur im Einklang sind. Die annähernden Werte für den Parameter 10Dq wurden berechnet; sie liegen im Bereich von 7,1 bis 7,8 kK.
Mit 1 Abbildung
6. Mitt.:M. Quastlerová-Hvastijová, J. Kohout undJ. Gao, Z. anorg. allgem. Chem., im Druck. 相似文献
Ligand field spectra of some cyanato-copper(II) complexes with ligands from the quinoline- and isoquinoline group
The ligand field spectra of complexes of the type Cu(NCO)2 L 2 (L=ligand from the quinoline or isoquinoline group) in the solid state were recorded. Only the spectrum of Cu(NCO)2(Quin)2 exhibits a single band and indicates a pseudooctahedral structure, while the spectra of the remaining complexes also contain shoulders in addition to the main band, or this band is composite, thus being in accordance with a planar structure. The approximate values of the parameter 10Dq were calculated and found to be in the range of 7.1 to 7.8 kK.
Mit 1 Abbildung
6. Mitt.:M. Quastlerová-Hvastijová, J. Kohout undJ. Gao, Z. anorg. allgem. Chem., im Druck. 相似文献
69.
Hitchcock PB Lappert MF Liu DS Sablong R 《Chemical communications (Cambridge, England)》2002,(17):1920-1921
The compounds [K((mu-N(SiMe3)C(Ph))2CH)(thf)2]infinity 1, [K(mu-N(SiMe3)C(Ph)C(H)C(Ph)NH)L]2 [L = (thf)2 2, tmen 3], [K(mu-NSi(Me)2C(Ph)C(H)C(Ph)N)(thf)3]2 4 and [K(N(H)C(Ph))2CH](thf)0.5 5 have been prepared from K[(N(SiMe3)C(Ph))2CH] and the X-ray structures of 1-4 are reported. 相似文献
70.
Michaël Deleuze Joseph Delhalle Barry T. Pickup 《Theoretical chemistry accounts》1992,82(3-4):309-319
Summary The vertical ionization potential and the related pole strength of a model alternant chain of 14 hydrogen atoms subject to a homogeneous electric field, parallel to the chain and of increasing intensity are calculated, in the framework of a 6–31G** basis set, at the second-order level of the many-body Green's function theory. Trends observed with orbital relaxation, pair removal and pair relaxation effects are interpreted in terms of deformations of the electron density. 相似文献