全文获取类型
收费全文 | 4188篇 |
免费 | 121篇 |
国内免费 | 23篇 |
专业分类
化学 | 3462篇 |
晶体学 | 49篇 |
力学 | 62篇 |
数学 | 170篇 |
物理学 | 589篇 |
出版年
2023年 | 23篇 |
2022年 | 18篇 |
2021年 | 45篇 |
2020年 | 56篇 |
2019年 | 53篇 |
2018年 | 35篇 |
2017年 | 37篇 |
2016年 | 75篇 |
2015年 | 83篇 |
2014年 | 97篇 |
2013年 | 205篇 |
2012年 | 223篇 |
2011年 | 291篇 |
2010年 | 147篇 |
2009年 | 153篇 |
2008年 | 315篇 |
2007年 | 251篇 |
2006年 | 296篇 |
2005年 | 285篇 |
2004年 | 246篇 |
2003年 | 223篇 |
2002年 | 205篇 |
2001年 | 59篇 |
2000年 | 74篇 |
1999年 | 49篇 |
1998年 | 38篇 |
1997年 | 42篇 |
1996年 | 49篇 |
1995年 | 44篇 |
1994年 | 44篇 |
1993年 | 46篇 |
1992年 | 34篇 |
1991年 | 34篇 |
1990年 | 27篇 |
1989年 | 17篇 |
1988年 | 24篇 |
1987年 | 27篇 |
1986年 | 24篇 |
1985年 | 37篇 |
1984年 | 42篇 |
1982年 | 27篇 |
1981年 | 32篇 |
1980年 | 32篇 |
1979年 | 19篇 |
1978年 | 21篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1973年 | 13篇 |
排序方式: 共有4332条查询结果,搜索用时 343 毫秒
31.
32.
Bond IA Budding E Conway MJ Fenton KB Fujii H Fujii Z Fujimoto M Hasegawa H Hayashida N Honda M Hotta N Humble JE Kabe S Kasahara K Kifune T Masaike A Matsubara Y Mitsui K Miura Y Mori M Murakami K Muraki Y Nagano M Nakamura K Nakamura T Norris PM Ohashi Y Okada A Saito T Sakata M Sato H Shibata S Shima M Storey JR Tanimori T Teshima M Torii S Uchino K Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review letters》1988,61(20):2292-2295
33.
Takuji Hirose Kumiko Naito Megumi Nakahara Hiroaki Shitara Yoshio Aoki Hiroyuki Nohira Bruce W. Baldwin 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):87-93
Two Kemp's acid diamides were synthesized and applied to chiral amine recognition using 1H NMR analysis. One derivative based on 1-(1-naphthyl)ethylamine had good chiral recognition of six amines and was useful to determine the optical purity for three amines, i.e., methylbenzylamine, 1-(1-naphthyl)ethylamine and 1- henylpropylamine,however, the cyclohexylethylamine derivative showed little discrimination for the amines studied. Together with the results for alkylamines, it was shown that aromatic structure was important for aromatic shielding anisotropy and –– interactions between host and guest. The structure of the 1-(1-naphthyl)ethylamine derivative in solution was also considered based on 1H NMR data and computer simulation. 相似文献
34.
Tetrakis-acridinyl peptide 1 assuming a right-handed helical stacked conformation of the acridinyl units can bind to DNA duplex with a very high affinity of 10(8) (M-bp)(-1) even at a high salt concentration of 0.2 M NaCl, irrespective of the base composition. Peptide 1 gave rise to 1600-times enhancement of its fluorescence upon binding to an AT polymer due to the collapse of this stacked structure, but the fluorescence is not enhanced with a GC polymer, though the binding constants of 1 for both polymers were the same. 相似文献
35.
Okada T Komatsu K Kawamoto T Yamanaka T Kagi H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(10):2423-2427
In situ Raman spectroscopic measurements of water in the region of OH vibration were conducted up to 0.4 GPa at 23 and 52 degrees C. The frequencies of the decomposed OH stretching bands initially decreased with increasing pressure, reached a minimum at 0.15 GPa and increased up to 0.3 GPa and then decreased, which corresponds to the variations of the strength of hydrogen bonding. This variation was observed at 23 degrees C, but not at 52 degrees C, which suggests a change in pressure dependence on the hydrogen bond interaction between these two temperatures. Based on the equilibration model between hydrogen-bonded and nonhydrogen-bonded molecules, the present experimental results indicate that the pressure variation of the viscosity depends on the ratio of hydrogen-bonded molecules, rather than the strength of hydrogen bonding between molecules. 相似文献
36.
Hiroyuki Higuchi Kazuhiro Takatsu Tetsuo Otsubo Yoshiteru Sakata Soichi Misumi 《Tetrahedron letters》1982,23(6):671-672
A novel cage compound was obtained by irradiation of a quadruple-layered dithiacyclophane and showed thermally reverse reaction. 相似文献
37.
Nishida H Miyazaki Y Kitamura Y Ohashi M Matsusue T Okamoto A Hosaka Y Ohnishi S Mochizuki H 《Chemical & pharmaceutical bulletin》2001,49(10):1237-1244
Intravascular clot formation is an important factor in a number of cardiovascular diseases. Therefore, the prevention of blood coagulation has become a major target for new therapeutic agents. One attractive approach is the inhibition of factor Xa (FXa), which is a key enzyme in coagulation cascade responsible for the generation of thrombin by limited proteolysis of its zymogen, prothrombin. We have investigated 1-arylsulfonyl-3-piperazinone derivatives, containing a 4-(piperidino)pyridine group in place of guanidino and/or amidino groups, and discovered compound M55113 (30a: 4-[(6-Chloro-2-naphthalenyl)sulfonyl]-1-[[1-(4-pyridinyl)-4-piperidinyl]methyl]piperazinone), as a potent inhibitor of FXa (IC50=0.06 microM) with high selectivity for FXa over trypsin and thrombin. 相似文献
38.
Kenichi Oyaizu Junya Katoh Fumiaki Suzuki Mitsutoshi Jikei Kimihisa Yamamoto Hiroyuki Nishide Eishun Tsuchida 《先进技术聚合物》1991,2(3):155-159
Oligo(phenylene sulfide) (OPS) containing one disulfide bond at the end of the chain, which was obtained by the oxidative polymerization of diphenyl disulfide, had a relatively low Td10%(temperature for 10% weight loss) of 412 °C because of degradation of the disulfide bond. But this thermal cleavage of the disulfide bond promoted the curing reaction through thiophenoxy radical formation. OPS was allowed to react with diiodobenzene at 220 °C. The thermal stability of OPS was improved through the consumption of the disulfide bond and the coupling of the chain. 相似文献
39.
40.
Masafumi Unno Hiroyuki Murakami Satoshi Kagawa Hideyuki Matsumoto 《Silicon Chemistry》2007,3(3-4):195-198
Two new silanols bearing very bulky silyl groups, (i-Pr3
Si)3SiOH and (t − BuMe2Si)3SiOH were prepared by peracidoxidation of their respective silanes. The X − ray crystallographic analysis revealed that (t − BuMe2Si)3 SiOH forms a dimeric structure with hydrogen bonding, while (i − Pr3 Si)3 SiOH exists as a monomer in the crystal. The effects of the size of the substituents as well as the reactivity of these silanols
are discussed. 相似文献