全文获取类型
收费全文 | 1656篇 |
免费 | 47篇 |
国内免费 | 8篇 |
专业分类
化学 | 1199篇 |
晶体学 | 14篇 |
力学 | 19篇 |
数学 | 165篇 |
物理学 | 314篇 |
出版年
2022年 | 9篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 7篇 |
2017年 | 19篇 |
2016年 | 30篇 |
2015年 | 18篇 |
2014年 | 31篇 |
2013年 | 84篇 |
2012年 | 61篇 |
2011年 | 96篇 |
2010年 | 45篇 |
2009年 | 60篇 |
2008年 | 87篇 |
2007年 | 106篇 |
2006年 | 92篇 |
2005年 | 107篇 |
2004年 | 93篇 |
2003年 | 74篇 |
2002年 | 75篇 |
2001年 | 33篇 |
2000年 | 35篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 39篇 |
1996年 | 28篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 23篇 |
1983年 | 14篇 |
1982年 | 25篇 |
1981年 | 19篇 |
1980年 | 22篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 19篇 |
1974年 | 14篇 |
1973年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有1711条查询结果,搜索用时 78 毫秒
91.
Watanabe M Ikagawa A Wang H Murata K Ikariya T 《Journal of the American Chemical Society》2004,126(36):11148-11149
Well-defined chiral Ru amido complexes promoted asymmetric Michael addition of 1,3-dicarbonyl compounds including malonates, beta-keto esters, and 1,3-diketones to nitroalkenes to give the corresponding adducts with excellent ees and in excellent yields. 相似文献
92.
Nakanishi M Eguchi A Akuta T Nagoshi E Fujita S Okabe J Senda T Hasegawa M 《Current protein & peptide science》2003,4(2):141-150
Improving the performance of non-viral gene-delivery vehicles that consist of synthetic compounds and nucleic acids is a key to successful gene therapy. Supplementing synthetic vehicles with various biological functions by using natural or artificial peptides is a promising approach with which to achieve this goal. One of the obstacles hindering this effort is that some of the potentially useful peptides, especially those with many basic amino acid residues, interfere with the formation of the complex owing to strong electrostatic interactions with the nucleic acid. In this review, we describe our recent work in examining the potential of these peptides in gene delivery, using a recombinant lambda phage particle as the model for the gene-delivery complex. Lambda phage encapsulates large duplex DNA in a rigid polyplex-like shell with a diameter of 55 nm, and can display various peptides on this capsid, independently of particle formation. By examining the expression of marker genes encapsulated in the phage capsid, we have demonstrated that the protein transduction domain of HIV Tat protein and the nuclear localization signal derived from SV40 T antigen can remarkably facilitate the delivery of these marker genes across the two major barriers, the cell membrane and the nuclear membrane, respectively. Our results indicate that these basic peptides can constitute effective components of synthetic gene-transfer complexes, as long as sufficient copies are displayed on the outer surface of the complex. 相似文献
93.
A spin-probe ESR study has been made on the dynamics of 2-propanol and water molecules in the nanochannel of MCM-41 at various temperatures. In the former system, 2-propanol is separated into two phases: one with molecules immobilized in the ESR time scale and the other with mobile ones, even at temperatures more than 40 degrees higher than the bulk melting point. In the case of water, on the other hand, only the "immobilized" water was detected at a temperature as high as 313 K. At higher temperature, spin-probe molecule undergoes anisotropic rotational diffusion to reduce resistance from the solvent molecules in the nanochannel. These results are explained in relation to the intermolecular network intensified in the nanochannel. Static as well as dynamic structures of these solutions have been discussed. 相似文献
94.
Prof. Dr. Yasuchika Hasegawa Takafumi Matsui Dr. Yuichi Kitagawa Dr. Takayuki Nakanishi Dr. Tomohiro Seki Prof. Dr. Hajime Ito Prof. Dr. Yuta Nakasaka Prof. Dr. Takao Masuda Prof. Dr. Koji Fushimi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12308-12315
Oxygen-sensitive and near-infrared (NIR) luminescent YbIII coordination polymers incorporating ligands based on pyrene derivatives were synthesized: YbIII–TBAPy and YbIII–TIAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoate)pyrene; TIAPy: 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene). The coordination structures of these materials have been characterized by means of electrospray ionization mass spectrometry, X-ray diffraction analysis, and thermogravimetric analysis. Moreover, the porous structure of YbIII–TIAPy has been evaluated by measuring its N2 adsorption isotherm. The NIR luminescence properties of YbIII–TBAPy and YbIII–TIAPy have been examined by acquiring emission spectra and determining emission lifetimes under air or argon and in vacuo. YbIII–TIAPy exhibited high thermal stability (with a decomposition temperature of 400 °C), intense luminescence (with an emission quantum yield under argon of 6.6 %), and effective oxygen-sensing characteristics. These results suggest that NIR luminescent YbIII coordination polymers prepared using pyrene derivatives could have applications in novel thermo-stable oxygen sensors. 相似文献
95.
96.
97.
98.
99.
100.