全文获取类型
收费全文 | 321634篇 |
免费 | 4511篇 |
国内免费 | 1620篇 |
专业分类
化学 | 175891篇 |
晶体学 | 4550篇 |
力学 | 13422篇 |
综合类 | 53篇 |
数学 | 36915篇 |
物理学 | 96934篇 |
出版年
2021年 | 2004篇 |
2020年 | 2247篇 |
2019年 | 2217篇 |
2018年 | 2167篇 |
2017年 | 2081篇 |
2016年 | 4162篇 |
2015年 | 3514篇 |
2014年 | 4780篇 |
2013年 | 14505篇 |
2012年 | 11382篇 |
2011年 | 14002篇 |
2010年 | 8728篇 |
2009年 | 8665篇 |
2008年 | 12841篇 |
2007年 | 12982篇 |
2006年 | 12612篇 |
2005年 | 11469篇 |
2004年 | 10314篇 |
2003年 | 9080篇 |
2002年 | 8937篇 |
2001年 | 10233篇 |
2000年 | 7818篇 |
1999年 | 6222篇 |
1998年 | 4985篇 |
1997年 | 4803篇 |
1996年 | 4849篇 |
1995年 | 4425篇 |
1994年 | 4157篇 |
1993年 | 3992篇 |
1992年 | 4476篇 |
1991年 | 4344篇 |
1990年 | 4037篇 |
1989年 | 3851篇 |
1988年 | 4143篇 |
1987年 | 3803篇 |
1986年 | 3689篇 |
1985年 | 5332篇 |
1984年 | 5406篇 |
1983年 | 4385篇 |
1982年 | 4762篇 |
1981年 | 4795篇 |
1980年 | 4549篇 |
1979年 | 4664篇 |
1978年 | 4667篇 |
1977年 | 4646篇 |
1976年 | 4598篇 |
1975年 | 4510篇 |
1974年 | 4356篇 |
1973年 | 4527篇 |
1972年 | 2570篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Kang Il Yoo Ji Yeong Jeon Su Jeong Ryu Giri Nam Hyewon Youn Eun Young Choi 《Experimental & molecular medicine》2015,47(2):e140
In allogeneic transplantation, including the B6 anti-BALB.B settings, H60 and H4 are two representative dominant minor histocompatibility antigens that induce strong CD8 T-cell responses. With different distribution patterns, H60 expression is restricted to hematopoietic cells, whereas H4 is ubiquitously expressed. H60-specific CD8 T-cell response has been known to be dominant in most cases of B6 anti-BALB.B allo-responses, except in the case of skin transplantation. To understand the mechanism underlying the subdominance of H60 during allogeneic skin transplantation, we investigated the dynamics of the H60-specific CD8 T cells in B6 mice transplanted with allogeneic BALB.B tail skin. Unexpectedly, longitudinal bioluminescence imaging and flow cytometric analyses revealed that H60-specific CD8 T cells were not always subdominant to H4-specific cells but instead showed a brief dominance before the H4 response became predominant. H60-specific CD8 T cells could expand in the draining lymph node and migrate to the BALB.B allografts, indicating their active participation in the anti-BALB.B allo-response. Enhancing the frequencies of H60-reactive CD8 T cells prior to skin transplantation reversed the immune hierarchy between H60 and H4. Additionally, H60 became predominant when antigen presentation was limited to the direct pathway. However, when antigen presentation was restricted to the indirect pathway, the expansion of H60-specific CD8 T cells was limited, whereas H4-specific CD8 T cells expanded significantly, suggesting that the temporary immunodominance and eventual subdominance of H60 could be due to their reliance on the direct antigen presentation pathway. These results enhance our understanding of the immunodominance phenomenon following allogeneic tissue transplantation. 相似文献
2.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
3.
4.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
5.
6.
7.
8.
9.
Unsymmetrical Pyrene‐Fused Phthalocyanine Derivatives: Synthesis,Structure, and Properties 下载免费PDF全文
Houhe Pan Chao Chen Kang Wang Prof. Dr. Wenjun Li Prof. Dr. Jianzhuang Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3168-3173
Novel pyrene‐fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17‐hexakis(2,6‐dimethylphenoxy)‐22,25‐diaza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz‐pyrene)(OC8H9)6] ( 1 ) and 2,3,9,10‐tra(2,6‐dimethylphenoxy)‐15,18,22,25‐traza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz‐pyrene)2(OC8H9)4] ( 2 ) were isolated for the first time. These unsymmetrical pyrene‐fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene‐fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X‐ray diffraction analysis of 1 , representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene. 相似文献
10.