全文获取类型
收费全文 | 2378篇 |
免费 | 59篇 |
国内免费 | 9篇 |
专业分类
化学 | 1511篇 |
晶体学 | 13篇 |
力学 | 20篇 |
综合类 | 1篇 |
数学 | 259篇 |
物理学 | 642篇 |
出版年
2020年 | 31篇 |
2019年 | 21篇 |
2018年 | 18篇 |
2016年 | 46篇 |
2015年 | 38篇 |
2014年 | 59篇 |
2013年 | 79篇 |
2012年 | 67篇 |
2011年 | 113篇 |
2010年 | 66篇 |
2009年 | 62篇 |
2008年 | 80篇 |
2007年 | 119篇 |
2006年 | 90篇 |
2005年 | 83篇 |
2004年 | 71篇 |
2003年 | 73篇 |
2002年 | 74篇 |
2001年 | 45篇 |
2000年 | 43篇 |
1999年 | 33篇 |
1998年 | 27篇 |
1997年 | 35篇 |
1996年 | 43篇 |
1995年 | 51篇 |
1994年 | 52篇 |
1993年 | 40篇 |
1992年 | 29篇 |
1991年 | 41篇 |
1990年 | 30篇 |
1989年 | 33篇 |
1988年 | 31篇 |
1987年 | 23篇 |
1986年 | 37篇 |
1985年 | 34篇 |
1984年 | 36篇 |
1983年 | 18篇 |
1982年 | 31篇 |
1981年 | 35篇 |
1980年 | 31篇 |
1979年 | 25篇 |
1978年 | 30篇 |
1977年 | 35篇 |
1976年 | 21篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1972年 | 12篇 |
1969年 | 13篇 |
1967年 | 15篇 |
1930年 | 12篇 |
排序方式: 共有2446条查询结果,搜索用时 15 毫秒
961.
R. Hofmann 《Annalen der Physik》2009,18(9):634-639
Based on SU(2) Yang‐Mills thermodynamics we interprete Aracde2's and the results of earlier radio‐surveys on low‐frequency cosmic microwave background (CMB) line temperatures as a phase‐boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields of the CMB whose intensity is nulled by that of Planck distributed calibrator photons. The CMB baseline temperature thus is identified with the critical temperature of the deconfining‐preconfining transition. 相似文献
962.
Gangavaram V. M. Sharma Dr. Bommagani Shoban Babu Kallaganti V. S. Ramakrishna Pendem Nagendar Dr. Ajit C. Kunwar Dr. Peter Schramm Carsten Baldauf Dr. Hans‐Jörg Hofmann Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(22):5552-5566
Origami peptides : A novel class of foldamers consisting of α/δ‐hybrid peptides has been investigated theoretically and experimentally by exploiting the rigidity of the side chain of a new δ‐amino acid prepared from D ‐glucose and D ‐xylose with a furanose side chain (see figure).
963.
Micro‐beam Laue alignment of multi‐reflection Bragg coherent diffraction imaging measurements 下载免费PDF全文
Felix Hofmann Nicholas W. Phillips Ross J. Harder Wenjun Liu Jesse N. Clark Ian K. Robinson Brian Abbey 《Journal of synchrotron radiation》2017,24(5):1048-1055
Multi‐reflection Bragg coherent diffraction imaging has the potential to allow three‐dimensional (3D) resolved measurements of the full lattice strain tensor in specific micro‐crystals. Until now such measurements were hampered by the need for laborious, time‐intensive alignment procedures. Here a different approach is demonstrated, using micro‐beam Laue X‐ray diffraction to first determine the lattice orientation of the micro‐crystal. This information is then used to rapidly align coherent diffraction measurements of three or more reflections from the crystal. Based on these, 3D strain and stress fields in the crystal are successfully determined. This approach is demonstrated on a focused ion beam milled micro‐crystal from which six reflections could be measured. Since information from more than three independent reflections is available, the reliability of the phases retrieved from the coherent diffraction data can be assessed. Our results show that rapid, reliable 3D coherent diffraction measurements of the full lattice strain tensor in specific micro‐crystals are now feasible and can be successfully carried out even in heavily distorted samples. 相似文献
964.
I. Maden R. Maduta J. Hofmann S. Jakirlić J. Kriegseis C. Tropea S. Grundmann 《Flow, Turbulence and Combustion》2016,97(4):1047-1069
Complementary experimental and computational study on flow separation delay at a NACA 0015 airfoil affected by a DBD (Dielectric-Barrier-Discharge) plasma actuator is presented. The effect of the DBD plasma-actuator on the flow development towards its appropriate control is accounted through a relevant body force representing a source term in the equation of motion. The spatial distribution of the force is calculated from the time-averaged properties of the experimentally obtained (by particle image velocimetry - PIV) velocity field by applying the Reynolds-Averaged Navier-Stokes equations. The study focusses in particular on the specific plasma-related turbulence production in the equations governing the Reynolds-stress tensor. Prior to studying the airfoil configuration the computational determination of the body force and corresponding turbulence generation rate is analyzed in a wall jet flow induced by the DBD plasma actuator. 相似文献
965.
S.?Heinz V.?Comas S.?Hofmann D.?Ackermann J.?Heredia F.?P.?He?berger J.?Khuyagbaatar B.?Kindler B.?Lommel R.?Mann 《The European Physical Journal A - Hadrons and Nuclei》2010,43(2):181-184
We investigated the capture stage and successive nucleon transfer from the projectile to the target in the superheavy system
64
28Ni + 207
82Pb (Z
proj. + Z
target = 110) . The target-like transfer products were detected at forward angles of (0±2) degrees, such, we selected nuclei resulting
from central collisions. The data reveal several analogies to cold fusion reactions leading to superheavy elements. The observations
are in accordance with the two-center shell model. The experiments have been performed at the velocity filter SHIP at GSI. 相似文献
966.
F.?P.?He?berger S.?Antalic D.?Ackermann S.?Heinz S.?Hofmann J.?Khuyagbaatar B.?Kindler I.?Kojouharov B.?Lommel R.?Mann 《The European Physical Journal A - Hadrons and Nuclei》2010,43(2):175-180
The isotope 261Bh was produced in the reaction 209Bi(54Cr, 2n)261Bh and its \( \alpha\) decay has been remeasured. It was found that it populates by an unhindered transition of \( \approx\) 10 MeV an excited level at E * > 350 keV in the daughter nucleus 257Db . The latter decays by internal transitions either into the isomeric state or the ground state. A somewhat improved half-life value of T 1/2 = 11.8+3.9 -2.4 ms was obtained for 261Bh . The data support the previous assignment of the \( \alpha\) activities 257Db (1) and 257Db (2) to the isomer and to the ground state, respectively. No evidence for an isomeric state in 261Bh decaying by \( \alpha\) emission was found. Based on the experimental results and theoretical calculations a partial decay scheme of 261Bh including spin and parity assignments of the ground-state and excited levels in the daughter nucleus 257Db populated by the \( \alpha\) decay and succeeding internal transitions have been suggested. 261Bh represents so far the heaviest nucleus for which such an attempt has been made. No spontaneous fission (SF) events that could be attributed to 261Bh were observed, resulting in an SF branching b SF < 0.05 . The measured production cross-section is (64±15) pb at E * = 22 MeV. 相似文献
967.
Stphane Baeriswyl Sacha Javor Achim Stocker Tamis Darbre Jean‐Louis Reymond 《Helvetica chimica acta》2019,102(9)
Dendrimers are regularly branched molecular trees which are notoriously difficult to crystallize. Herein we report the crystal structure of a C‐fucosylated second generation peptide dendrimer as complex with lectin LecB in which the only dendrimer‐lectin contact is the LecB bound glycoside (PDB 6S5S). In contrast to a previously reported crystal structure of a first‐generation peptide dendrimer as LecB complex in which the dendrimer formed trimers connected by intermolecular β‐sheets (PDB 5D2A), the present structure features a globular monomeric state held together by intramolecular backbone hydrogen bonds and assembled into a non‐covalent dimer stabilized by hydrophobic contacts between leucine side‐chains and proline‐phenylalanine CH‐π stacking interactions. Molecular dynamics and circular dichroism studies suggest that this crystal structure resembles the structure of the peptide dendrimer in solution. Structures of a partially resolved dendrimer (PDB 6S5R) and of C‐fucosylated disulfide bridged peptide dimers connecting different LecB tetramers are also reported (PDB 6S7G, PDB 6S5P). 相似文献
968.
María Entrialgo-Castaño Anthony E. Salvucci Andreas Lendlein Dieter Hofmann 《Macromolecular Symposia》2008,269(1):47-64
This paper reports computational simulations at two different scales employed to investigate the hydrolytic degradation of two homopolyesters: polyglycolide, PGA and poly(L-lactide), PLLA. Atomistic bulk models were used to investigate the dry and various hydrated states of the two systems. In addition, the first moments of contact between the polymers and water were studied employing atomistic interface models. A higher affinity of water to polyglycolide in comparison with poly(L-lactide) was observed, while diffusion of water was found to be lower in the first polymer. Quantum chemical calculations for the first step of the water-assisted hydrolysis revealed a higher resistance to hydrolytical scission of the L-lactyl units in comparison to glycolyl units. 相似文献
969.
970.
C. Thierfelder P. Schwerdtfeger F. P. Heßberger S. Hofmann 《The European Physical Journal A - Hadrons and Nuclei》2008,36(2):227-231
The K -shell and L -shell ionizations potentials for 268
109Mt were calculated at the Dirac-Hartree-Fock level taking into account quantum electrodynamic and finite nuclear-size effects.
The K
α1 transition energies for different ionization states are accurately predicted and compared with recent experiments in the
α -decay of 272
111Rg . 相似文献