全文获取类型
收费全文 | 12677篇 |
免费 | 465篇 |
国内免费 | 78篇 |
专业分类
化学 | 9313篇 |
晶体学 | 93篇 |
力学 | 298篇 |
数学 | 1751篇 |
物理学 | 1765篇 |
出版年
2023年 | 79篇 |
2022年 | 101篇 |
2021年 | 147篇 |
2020年 | 227篇 |
2019年 | 176篇 |
2018年 | 154篇 |
2017年 | 127篇 |
2016年 | 309篇 |
2015年 | 275篇 |
2014年 | 319篇 |
2013年 | 606篇 |
2012年 | 828篇 |
2011年 | 1037篇 |
2010年 | 497篇 |
2009年 | 347篇 |
2008年 | 773篇 |
2007年 | 843篇 |
2006年 | 890篇 |
2005年 | 891篇 |
2004年 | 715篇 |
2003年 | 604篇 |
2002年 | 535篇 |
2001年 | 161篇 |
2000年 | 137篇 |
1999年 | 118篇 |
1998年 | 113篇 |
1997年 | 124篇 |
1996年 | 163篇 |
1995年 | 113篇 |
1994年 | 108篇 |
1993年 | 108篇 |
1992年 | 88篇 |
1991年 | 85篇 |
1990年 | 64篇 |
1989年 | 53篇 |
1988年 | 71篇 |
1987年 | 52篇 |
1985年 | 118篇 |
1984年 | 77篇 |
1983年 | 55篇 |
1982年 | 96篇 |
1981年 | 104篇 |
1980年 | 86篇 |
1979年 | 73篇 |
1978年 | 69篇 |
1977年 | 63篇 |
1976年 | 59篇 |
1975年 | 58篇 |
1974年 | 49篇 |
1973年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Yue Xuan Andrew J. Creese Julie A. Horner Helen J. Cooper 《Rapid communications in mass spectrometry : RCM》2009,23(13):1963-1969
We have applied high‐field asymmetric waveform ion mobility spectrometry (FAIMS) to the analysis of the phosphopeptides APLpSFRGSLPKSYVK, APLSFRGpSLPKSYVK, and APLSFRGSLPKpSYVK. The peptides have identical amino acid sequences and differ only in the site of phosphorylation. The results show that FAIMS is capable of at least partially separating these species. Separation was confirmed by coupling FAIMS with high‐resolution electron transfer dissociation (ETD) mass spectrometry. Phosphorylation is retained on the ETD peptide fragments thereby allowing assignment of the site of the modification. Co‐eluting phosphopeptides which differ only in the site of modification are frequently observed in liquid chromatography/tandem mass spectrometry phosphoproteomics experiments, and therefore these proof‐of‐principle results have implications for the application of FAIMS in that field. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
Oliver G. Maupin Andrew D. Baczewski Peter J. Love Andrew J. Landahl 《Entropy (Basel, Switzerland)》2021,23(6)
We present example quantum chemistry programs written with JaqalPaq, a python meta-programming language used to code in Jaqal (Just Another Quantum Assembly Language). These JaqalPaq algorithms are intended to be run on the Quantum Scientific Computing Open User Testbed (QSCOUT) platform at Sandia National Laboratories. Our exemplars use the variational quantum eigensolver (VQE) quantum algorithm to compute the ground state energies of the , , and molecules. Since the exemplars focus on how to program in JaqalPaq, the calculations of the second-quantized Hamiltonians are performed with the PySCF python package, and the mappings of the fermions to qubits are obtained from the OpenFermion python package. Using the emulator functionality of JaqalPaq, we emulate how these exemplars would be executed on an error-free QSCOUT platform and compare the emulated computation of the bond-dissociation curves for these molecules with their exact forms within the relevant basis. 相似文献
994.
995.
S.Y. Frankie Mak Gary C.H. Chiang James E.P. Davidson John E. Davies Andrew Ayscough Gilles Pain Jonathan W. Burton Andrew B. Holmes 《Tetrahedron: Asymmetry》2009,20(6-8):921-944
The enantioselective synthesis of a number of simplified analogues of the cytotoxic natural product eleutherobin is reported. 相似文献
996.
Theodore F. Baumann Ticora V. Jones Thomas Wilson Andrew P. Saab Robert S. Maxwell 《Journal of polymer science. Part A, Polymer chemistry》2009,47(10):2589-2596
We report the synthesis and characterization of novel elastomeric nanocomposites containing polyhedral oligomeric silsesquioxanes (POSS) as both the cross‐linker and filler within a polydimethylsiloxane (PDMS) polymer matrix. These polymer composites were prepared through the reaction of octasilane‐POSS (OS‐POSS) with vinyl‐terminated PDMS chains using hydrosilylation chemistry. In addition, larger super‐POSS cross‐linkers, consisting of two pendant hepta(isobutyl)POSS molecules attached to a central octasilane‐POSS core, were also used in the fabrication of the PDMS composites. The chemical incorporation of these POSS cross‐linkers into the PDMS network was verified by solid‐state 1H magic angle spinning NMR. Based on dynamic mechanical analysis, the PDMS nanocomposites prepared with the octafunctional OS‐POSS cross‐linker exhibited enhanced mechanical properties relative to polymer systems prepared with the tetrafunctional TDSS cross‐linker at equivalent loading levels. The observed improvements in mechanical properties can be attributed to the increased dimensionality of the POSS cross‐linker. The PDMS elastomers synthesized from the larger super‐POSS molecule showed improved mechanical properties relative to both the TDSS and OS‐POSS composites due to the increased volume‐fraction of POSS filler in the polymer matrix. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2589–2596, 2009 相似文献
997.
We study the three point genus zero Gromov-Witten invariants on the Grassmannians which parametrize non-maximal isotropic
subspaces in a vector space equipped with a nondegenerate symmetric or skew-symmetric form. We establish Pieri rules for the
classical cohomology and the small quantum cohomology ring of these varieties, which give a combinatorial formula for the
product of any Schubert class with certain special Schubert classes. We also give presentations of these rings, with integer
coefficients, in terms of special Schubert class generators and relations. 相似文献
998.
999.
Andrew V. Sills 《Journal of Combinatorial Theory, Series A》2008,115(1):67-83
We provide a bijective map from the partitions enumerated by the series side of the Rogers-Selberg mod 7 identities onto partitions associated with a special case of Basil Gordon's combinatorial generalization of the Rogers-Ramanujan identities. The implications of applying the same map to a special case of David Bressoud's even modulus analog of Gordon's theorem are also explored. 相似文献
1000.