全文获取类型
收费全文 | 8121篇 |
免费 | 1039篇 |
国内免费 | 557篇 |
专业分类
化学 | 5889篇 |
晶体学 | 37篇 |
力学 | 370篇 |
综合类 | 16篇 |
数学 | 903篇 |
物理学 | 2502篇 |
出版年
2024年 | 23篇 |
2023年 | 171篇 |
2022年 | 236篇 |
2021年 | 318篇 |
2020年 | 322篇 |
2019年 | 266篇 |
2018年 | 250篇 |
2017年 | 194篇 |
2016年 | 363篇 |
2015年 | 315篇 |
2014年 | 420篇 |
2013年 | 529篇 |
2012年 | 711篇 |
2011年 | 754篇 |
2010年 | 458篇 |
2009年 | 393篇 |
2008年 | 527篇 |
2007年 | 448篇 |
2006年 | 417篇 |
2005年 | 344篇 |
2004年 | 262篇 |
2003年 | 208篇 |
2002年 | 172篇 |
2001年 | 137篇 |
2000年 | 130篇 |
1999年 | 139篇 |
1998年 | 119篇 |
1997年 | 101篇 |
1996年 | 136篇 |
1995年 | 110篇 |
1994年 | 74篇 |
1993年 | 69篇 |
1992年 | 73篇 |
1991年 | 58篇 |
1990年 | 77篇 |
1989年 | 56篇 |
1988年 | 38篇 |
1987年 | 30篇 |
1986年 | 28篇 |
1985年 | 23篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1980年 | 11篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1973年 | 14篇 |
排序方式: 共有9717条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
Siwy Z Trofin L Kohli P Baker LA Trautmann C Martin CR 《Journal of the American Chemical Society》2005,127(14):5000-5001
There is increasing interest in the concept of using nanopores as the sensing elements in biosensors. The nanopore most often used is the alpha-hemolysin protein channel, and the sensor consists of a single channel embedded within a lipid bilayer membrane. An ionic current is passed through the channel, and analyte species are detected as transient blocks in this current associated with translocation of the analyte through the channel-stochastic sensing. While this is an extremely promising sensing paradigm, it would be advantageous to eliminate the very fragile lipid bilayer membrane and perhaps to replace the biological nanopore with an abiotic equivalent. We describe here a new family of protein biosensors that are based on conically shaped gold nanotubes embedded within a mechanical and chemically robust polymeric membrane. While these sensors also function by passing an ion current through the nanotube, the sensing paradigm is different from the previous devices in that a transient change in the current is not observed. Instead, the protein analyte binds to a biochemical molecular-recognition agent at the mouth of the conical nanotube, resulting in complete blockage of the ion current. Three different molecular-recognition agents, and correspondingly three different protein analytes, were investigated: (i) biotin/streptavidin, (ii) protein-G/immunoglobulin, and (iii) an antibody to the protein ricin with ricin as the analyte. 相似文献
16.
17.
18.
19.
20.
Ser Peow Tan 《Geometriae Dedicata》1996,62(2):209-225
Let M be a compact orientable surface with nonempty boundary (x(M)<0) and fundamental group . Let be a geodesic on M (with a fixed hyperbolic structure), and let W be a (cyclically reduced) word in a fixed set
of generators of which represents . In this paper, we give an algorithm to count the number of self-intersections of in terms of W, generalizing a result of Birman and Series, where an algorithm was given to decide if was simple. Some applications of the algorithm to surfaces with one boundary and the Markoff spectrum are also given. 相似文献