全文获取类型
收费全文 | 1883篇 |
免费 | 53篇 |
国内免费 | 11篇 |
专业分类
化学 | 1171篇 |
晶体学 | 10篇 |
力学 | 62篇 |
综合类 | 1篇 |
数学 | 193篇 |
物理学 | 510篇 |
出版年
2020年 | 13篇 |
2019年 | 16篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 22篇 |
2014年 | 27篇 |
2013年 | 83篇 |
2012年 | 82篇 |
2011年 | 103篇 |
2010年 | 44篇 |
2009年 | 53篇 |
2008年 | 87篇 |
2007年 | 94篇 |
2006年 | 89篇 |
2005年 | 79篇 |
2004年 | 80篇 |
2003年 | 60篇 |
2002年 | 49篇 |
2001年 | 38篇 |
2000年 | 40篇 |
1999年 | 46篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 24篇 |
1995年 | 40篇 |
1994年 | 35篇 |
1993年 | 35篇 |
1992年 | 45篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 17篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 33篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 26篇 |
1978年 | 25篇 |
1977年 | 25篇 |
1976年 | 20篇 |
1975年 | 21篇 |
1974年 | 29篇 |
1973年 | 23篇 |
1972年 | 12篇 |
1971年 | 13篇 |
1934年 | 16篇 |
排序方式: 共有1947条查询结果,搜索用时 8 毫秒
81.
82.
A. Saifer M. Kornblum S. P. Worden I. B. Rushing I. P. Barnes A. P. Surer M. Farren Greta Hammarsten B. Melichar L. Vsetecka S. A. Poworinskaja Raimonde Duval J. M. Le Goff E. Justin-Mueller G. Haslewood E. King A. T. Cameron J. S. Guthrie F. D. White Th. Findley Regine Kapeller-Adler N. P. Meschkowa Rangier Lafrançaise P. A. Clifford H. J. Wichmann F. Timm E. Komm F. Kiermeier und A. Douglas-Sauermann 《Fresenius' Journal of Analytical Chemistry》1938,115(7-8):296-300
Ohne Zusammenfassung 相似文献
83.
S. B. Clough N. S. Schneider A. O. King 《Journal of Macromolecular Science: Physics》2013,52(4):641-648
Small-angle X-ray scattering is shown to be an effective technique, complementary to mechanical and thermal methods, for the study of structural ordering in polyurethane elastomers. Wide variations in intensity were found for different sample compositions and are interpreted in terms of the degree of hard segment aggregation. The results support previous conclusions regarding the organization in these samples based on analysis by scanning thermal methods. The polyether polyurethanes studied showed a higher degree of organization than the equivalent polyesters, and longer urethane segments enhance the extent of domain structure. Studies of the temperature dependence of scattering strengthen the previous assignment of a transition at about 150°C to the disordering of domain structure. 相似文献
84.
Dr. Valerie H. L. Wong Dr. Sai V. C. Vummaleti Prof. Luigi Cavallo Dr. Andrew J. P. White Prof. Steven P. Nolan Dr. King Kuok Hii 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13320-13327
A general synthetic route was used to prepare 15 new N‐heterocyclic carbene (NHC)–AgI complexes bearing anionic carboxylate ligands [Ag(NHC)(O2CR)], including a homologous series of complexes of sterically flexible ITent ligands, which permit a systematic spectroscopic and theoretical study of the structural and electronic features of these compounds. The complexes displayed a significant ligand‐accelerated effect in the intramolecular cyclisation of propargylic amides to oxazolidines. The substrate scope is highly complementary to that previously achieved by NHC–Au and pyridyl–AgI complexes. 相似文献
85.
Steven S. Wesolowski Edward F. Valeev Rollin A. King Victor Baranovski Henry F. Schaefer III 《Molecular physics》2013,111(16):1227-1231
Atomic natural orbital (ANO) basis sets for calcium may produce surprisingly poor atomic and molecular properties and energetics. The weaknesses in these basis sets may be traced primarily to deficiencies within the sets of d functions which are incapable of effectively correlating the 3s and 3p electrons. Examples are given which show that addition of tight d functions to the ANO basis is required to achieve qualitatively correct energetics and structures for conventionally bonded calcium compounds. 相似文献
86.
87.
Bharat Kumar Ruth L. Viboh Margel C. Bonifacio William B. Thompson Jonathan C. Buttrick Babe C. Westlake Min‐Soo Kim Robert W. Zoellner Sergey A. Varganov Philipp Mrschel Jaroslav Teteruk Martin U. Schmidt Benjamin T. King 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2012,124(51):13071-13071
88.
J. Mark Parnis Kaitlynn A. King Matthew G. K. Thompson 《Journal of mass spectrometry : JMS》2013,48(11):1224-1231
The chemistry of ionized acetone:Ar mixtures under varied ionizing electron density conditions has been studied using matrix‐isolation techniques. Gaseous acetone diluted in excess argon gas was subjected to electron bombardment with 300 eV electrons at currents between 20 and 200 μA. Linear wire ‘pin’ and metal ‘plate’ electron collector geometries were employed, allowing a wide range of electron density conditions to be explored. The products of subsequent reaction processes were matrix isolated and analyzed by Fourier transform infrared absorption spectroscopy. Products included methane, ketene, 1‐propen‐2‐ol (the enol isomer of acetone), CO, HCO, ethane, ethane, acetylene and CCCO. Product absolute and relative yields varied with acetone number density, the choice of anode geometry and the rate of electron bombardment. The overall chemistry observed is rationalized in terms of mechanistic steps involving unimolecular cation decomposition, ion–molecule reactions, radical–radical reactions and dissociative recombination processes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
89.
90.
We derive production yields for massive pseudo-scalar and scalar axion-like-particles (ALPs), through non-linear Compton scattering of an electron in the background of low- and high-intensity electromagnetic fields. In particular, we focus on electromagnetic fields from Gaussian plane wave laser pulses. A detailed study of the angular distributions and effects of the scalar and pseudo-scalar masses is presented. It is shown that ultra-relativistic seed electrons can be used to produce scalars and pseudo-scalars with masses up to the order of the electron mass. We briefly discuss future applications of this work towards lab-based searches for light beyond-the-Standard-Model particles. 相似文献