全文获取类型
收费全文 | 2069篇 |
免费 | 80篇 |
国内免费 | 20篇 |
专业分类
化学 | 1285篇 |
晶体学 | 6篇 |
力学 | 40篇 |
数学 | 266篇 |
物理学 | 572篇 |
出版年
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 27篇 |
2019年 | 30篇 |
2018年 | 19篇 |
2017年 | 16篇 |
2016年 | 47篇 |
2015年 | 48篇 |
2014年 | 57篇 |
2013年 | 98篇 |
2012年 | 126篇 |
2011年 | 125篇 |
2010年 | 71篇 |
2009年 | 55篇 |
2008年 | 94篇 |
2007年 | 119篇 |
2006年 | 103篇 |
2005年 | 91篇 |
2004年 | 75篇 |
2003年 | 47篇 |
2002年 | 40篇 |
2001年 | 31篇 |
2000年 | 34篇 |
1999年 | 23篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 31篇 |
1995年 | 36篇 |
1994年 | 39篇 |
1993年 | 30篇 |
1992年 | 28篇 |
1991年 | 25篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 26篇 |
1985年 | 31篇 |
1984年 | 36篇 |
1983年 | 18篇 |
1982年 | 28篇 |
1981年 | 37篇 |
1980年 | 23篇 |
1979年 | 26篇 |
1978年 | 27篇 |
1977年 | 24篇 |
1976年 | 32篇 |
1975年 | 27篇 |
1974年 | 16篇 |
1973年 | 23篇 |
排序方式: 共有2169条查询结果,搜索用时 0 毫秒
81.
Suwannee Junyapoon Keith D. Bartle Andrew B. Ross Michael Cooke Brian F. Smethurst 《International journal of environmental analytical chemistry》2013,93(4):337-348
Abstract Trace volatile compounds emitted from both domestic and industrial landfills have been identified by programmed temperature vaporization injection (PTV) coupled to gas chromatography with detection by ion-trap mass spectrometry (GC-ITD/MS). The PTV injection system has been developed using a combination of two six-port valves to achieve problems of interference in GC-MS while loading sample. A large volume of landfill gas was re-concentrated onto a sorbent trap, then rapidly liberated into the GC-ITD/MS system by programmed thermal desorption. Using this method, trace volatile compounds in gases from both domestic and industrial landfills such as aromatic hydrocarbons, terpenes, chlorinated hydrocarbons, and sulfur compounds can be identified and quantified. 相似文献
82.
James F. Ross 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1443-1450
Nonhomogeneous copolymer systems that follow Markovian kinetics on a microscale will give non-Markovian sequence distributions in the polymer produced. This is because each microdomain is statistically independent of the others and the assumption of statistical stationarity does not apply. Equations that consider non-homogeneity, however, do apply and can reconcile Markovian kinetics and non-Markovian sequence distributions. Failures of systems to follow lower order Markovian mechanisms based on distribution data should be reviewed for nonhomogeneity. Complex mathematical models that can never be validated experimentally should only be considered if nonhomogeneity fails to explain the data adequately. 相似文献
83.
Zachary S. Kean Dr. Sergey Akbulatov Dr. Yancong Tian Prof. Ross A. Widenhoefer Dr. Roman Boulatov Prof. Stephen L. Craig 《Angewandte Chemie (International ed. in English)》2014,53(52):14508-14511
A catalyst that couples a photoswitch to the biaryl backbone of a chiral bis(phosphine) ligand, thus allowing photochemical manipulation of ligand geometry without perturbing the electronic structure is reported. The changes in catalyst activity and selectivity upon switching can be attributed to intramolecular mechanical forces, thus laying the foundation for a new class of catalysts whose selectivity can be varied smoothly and in situ over a useful range by controlling molecular stress experienced by the catalyst during turnover. Forces on the order of 100 pN are generated, thus leading to measurable changes in the enantioselectivities of asymmetric Heck arylations and Trost allylic alkylations. The differential coupling between applied force and competing stereochemical pathways is quantified and found to be more efficient for the Heck arylations. 相似文献
84.
85.
Stacey M. Frumm Zi Peng Fan Kenneth N. Ross Jeremy R. Duvall Supriya Gupta Lynn VerPlank Byung-Chul Suh Edward Holson Florence F. Wagner William B. Smith Ronald M. Paranal Christopher F. Bassil Jun Qi Giovanni Roti Andrew L. Kung James E. Bradner Nicola Tolliday Kimberly Stegmaier 《Chemistry & biology》2013,20(5):713-725
86.
87.
88.
89.
M.J. Grosskopf R.P. Drake C.C. Kuranz E.M. Rutter J.S. Ross N.L. Kugland C. Plechaty B.A. Remington A. Spitkovsky L. Gargate G. Gregori A. Bell C.D. Murphy J. Meinecke B. Reville Y. Sakawa Y. Kuramitsu H. Takabe H.-S. Park 《High Energy Density Physics》2013,9(1):192-197
Experiments investigating the physics of interpenetrating, collisionless, ablated plasma flows have become an important area of research in the high-energy-density field. In order to evaluate the feasibility of designing experiments that will generate a collisionless shock mediated by the Weibel instability on the National Ignition Facility (NIF) laser, computer simulations using the Center for Radiative Shock Hydrodynamics (CRASH) radiation-hydrodynamics model have been carried out. This paper reports assessment of whether the experiment can reach the required scale size while maintaining the low interflow collisionality necessary for the collisionless shock to form. Comparison of simulation results with data from Omega experiments shows the ability of the CRASH code to model these ablated systems. The combined results indicate that experiments on the NIF are capable of reaching the regimes necessary for the formation of a collisionless shock in a laboratory experiment. 相似文献
90.