全文获取类型
收费全文 | 2465篇 |
免费 | 132篇 |
国内免费 | 10篇 |
专业分类
化学 | 1906篇 |
晶体学 | 10篇 |
力学 | 51篇 |
综合类 | 2篇 |
数学 | 277篇 |
物理学 | 361篇 |
出版年
2023年 | 39篇 |
2022年 | 29篇 |
2021年 | 62篇 |
2020年 | 106篇 |
2019年 | 88篇 |
2018年 | 59篇 |
2017年 | 37篇 |
2016年 | 92篇 |
2015年 | 64篇 |
2014年 | 75篇 |
2013年 | 116篇 |
2012年 | 203篇 |
2011年 | 270篇 |
2010年 | 96篇 |
2009年 | 79篇 |
2008年 | 159篇 |
2007年 | 144篇 |
2006年 | 153篇 |
2005年 | 97篇 |
2004年 | 94篇 |
2003年 | 79篇 |
2002年 | 54篇 |
2001年 | 16篇 |
2000年 | 29篇 |
1999年 | 10篇 |
1998年 | 17篇 |
1996年 | 18篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 26篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 16篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1973年 | 10篇 |
1968年 | 7篇 |
1967年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有2607条查询结果,搜索用时 140 毫秒
31.
A network of solar carcinogenic/erythemal ultraviolet radiometers has been established in New Zealand. Daily integrated irradiances of this biologically harmful ultraviolet radiation for 1989, 1990 and 1991 are reported from radiometers located at Wellington (41°S) and Christchurch (43.5°S) and for 1990 and 1991 from the Auckland (37°S) radiometer. Although the monitoring program has not been running sufficiently long to discern any long-term changes in levels of solar ultraviolet radiation, shorter term trends are apparent, which are attributed to a seasonal cycle in levels of ozone at midlatitudes and changes in atmospheric aerosols. 相似文献
32.
Yongzheng Cong Khatereh Motamedchaboki Santosh A. Misal Yiran Liang Amanda J. Guise Thy Truong Romain Huguet Edward D. Plowey Ying Zhu Daniel Lopez-Ferrer Ryan T. Kelly 《Chemical science》2021,12(3):1001
We report on the combination of nanodroplet sample preparation, ultra-low-flow nanoLC, high-field asymmetric ion mobility spectrometry (FAIMS), and the latest-generation Orbitrap Eclipse Tribrid mass spectrometer for greatly improved single-cell proteome profiling. FAIMS effectively filtered out singly charged ions for more effective MS analysis of multiply charged peptides, resulting in an average of 1056 protein groups identified from single HeLa cells without MS1-level feature matching. This is 2.3 times more identifications than without FAIMS and a far greater level of proteome coverage for single mammalian cells than has been previously reported for a label-free study. Differential analysis of single microdissected motor neurons and interneurons from human spinal tissue indicated a similar level of proteome coverage, and the two subpopulations of cells were readily differentiated based on single-cell label-free quantification.The combination of nanodroplet sample preparation, ultra-low-flow nanoLC, high-field asymmetric ion mobility spectrometry (FAIMS) and latest-generation mass spectrometry instrumentation provides dramatically improved single-cell proteome profiling. 相似文献
33.
Castro C Karney WL Valencia MA Vu CM Pemberton RP 《Journal of the American Chemical Society》2005,127(27):9704-9705
Density functional and coupled cluster calculations show that facile thermal configuration change in [12]annulene occurs via a twist-coupled bond-shifting mechanism. The transition state for this process is highly aromatic with M?bius topology. At the CCSD(T)/cc-pVDZ//BH&HLYP/6-311+G** level, the isomerization of tri-trans-[12]annulene 1a (CTCTCT) to its di-trans isomer 2 (CCCTCT) via such a mechanism has a barrier of 18.0 kcal/mol, in good agreement with earlier experiments. Two other aromatic M?bius bond-shifting transition states were located that result in configuration change for other [12]annulene conformers. This mechanism contrasts sharply with diradical configuration change for acyclic polyenes and with planar bond-shifting mechanisms generally assumed for annulenes. This constitutes evidence that neutral M?bius aromatic annulenes play a role in the dynamic processes of neutral [4n]annulenes. 相似文献
34.
35.
36.
37.
38.
Mössbauer measurements in a-(Fe0.765Mn0.235)78Sn2Si6B14 have been performed with57Fe and119Sn. Both hyperfine fields show a kink near 70 K, indicating a freezing of the transverse spins. The ratio of the two hyperfine fields contains information about the correlation of the transverse spins. The ratioB
hf(Sn)/B
hf(Fe) stays constant aboveT
xy
and rises belowT
xy
. This indicates an alignment of the transverse spins on a local scale, as was also found inAuFe and a-FeZr. 相似文献
39.
40.