全文获取类型
收费全文 | 3787篇 |
免费 | 147篇 |
国内免费 | 11篇 |
专业分类
化学 | 2836篇 |
晶体学 | 53篇 |
力学 | 32篇 |
数学 | 168篇 |
物理学 | 856篇 |
出版年
2023年 | 22篇 |
2022年 | 28篇 |
2021年 | 40篇 |
2020年 | 78篇 |
2019年 | 63篇 |
2018年 | 59篇 |
2017年 | 40篇 |
2016年 | 104篇 |
2015年 | 75篇 |
2014年 | 104篇 |
2013年 | 170篇 |
2012年 | 250篇 |
2011年 | 310篇 |
2010年 | 153篇 |
2009年 | 145篇 |
2008年 | 246篇 |
2007年 | 243篇 |
2006年 | 246篇 |
2005年 | 237篇 |
2004年 | 200篇 |
2003年 | 163篇 |
2002年 | 153篇 |
2001年 | 66篇 |
2000年 | 56篇 |
1999年 | 39篇 |
1998年 | 41篇 |
1997年 | 39篇 |
1996年 | 40篇 |
1995年 | 23篇 |
1994年 | 30篇 |
1993年 | 20篇 |
1992年 | 35篇 |
1991年 | 19篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 22篇 |
1984年 | 34篇 |
1983年 | 25篇 |
1982年 | 28篇 |
1981年 | 17篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 23篇 |
1976年 | 16篇 |
1975年 | 18篇 |
1973年 | 9篇 |
排序方式: 共有3945条查询结果,搜索用时 15 毫秒
41.
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
42.
43.
1-Alkoxy-3-trimethylsilylmethyl- and 1-alkoxy-3-trimethylsilyl-l,3-butadienes () were newly prepared. The cycloaddition reactions of with various dienophiles including heterodienophiles were found to proceed very smoothly in a perfectly regiospecific mode. 相似文献
44.
Takayuki Abe Shingo Higashide Mitsuhiro Inoue Satoshi Akamaru 《Plasma Chemistry and Plasma Processing》2007,27(6):799-811
Fine particles were modified with a thin film of SnO2 by using a barrel sputtering system that is a dry process. The conditions for the preparation of SnO2 were studied by reactive sputtering onto a glass plate substrate. The optimal conditions for the preparation of tetragonal
SnO2 were identified as 60% partial oxygen pressure and 1.0 Pa total gas pressure with the substrate at room temperature. Under
the optimized conditions, the surfaces of Al flake particles were modified with a thin film of SnO2. XRD and SEM/EDS analysis of the prepared samples showed that the Al particle surfaces were uniformly modified by a thin
film of SnO2 in all cases. The film thicknesses were 80, 130, and 180 nm at RF outputs of 195, 350, and 490 W. These measured thicknesses
coincided with the values estimated from the interference colors of the samples. 相似文献
45.
Tsuyoshi Miura Satoshi Tsujino Kohtaro Goto Midori Noguchi Manabu Node Nobuyuki Imai 《Tetrahedron》2005,61(27):6518-6526
The use of the bisfluorous chain-type propanoyl (Bfp) group as a fluorous protective group made it possible to rapidly synthesize the Gb2 and Gb3 oligosaccharide derivatives by a simple fluorous-organic extraction purification. Furthermore, the fluorescence-labeled Gb2 and Gb3 oligosaccharides were prepared as a potential Vero Toxins detecting reagent. 相似文献
46.
Yoshihiro Itoh Masamitsu Inoue Tomoko Takahashi Akira Hachimori Satoshi Suzuki 《Journal of polymer science. Part A, Polymer chemistry》1995,33(7):1069-1074
Alternating and random copolymers of 9-phenanthrylmethyl methacrylate or 2-(9-carbazolyl)ethyl methacrylate with styrene were synthesized and their fluorescence properties were examined. There was no noticeable difference in the spectral features of the alternating and random copolymers in tetrahydrofuran (THF), demonstrating that this type of polymers have no quenching sites in the polymer chains. The fluorescence quenching studies indicated that the alternating copolymers permitted singlet-state energy migration as efficiently as the corresponding random copolymers but less efficiently than the random copolymers with higher chromophore contents. These results strongly suggest that to be chromophores close to each other is most important for facilitation of an intramolecular energy migration. © 1995 John Wiley & Sons, Inc. 相似文献
47.
T Nishi M Sakurai S Sato M Kataoka Y Morisawa 《Chemical & pharmaceutical bulletin》1989,37(8):2200-2203
An asymmetric synthetic route to 2-substituted-3-aminocarbonyl propionic acid, which is the significant component of low-molecular-weight renin inhibitors, is described. The key step of this synthesis is diastereoselective alkylation by using chiral oxazolidinone and benzyl bromoacetate. 相似文献
48.
M. Takagaki K. Ono S-I. Masunaga Y. Kinashi Y. Sakurai T. Kobayashi S-I. Miyatake N. Hashimoto 《Journal of Radioanalytical and Nuclear Chemistry》2001,247(2):389-392
Quantitative determination of ppb-order 10B was carried out in a small number of cultured tumor cells by particle tracks by the 10B(n,)7Li reactions using solid state nuclear track detector (SSNTD) for boron neutron capture therapy research. The detection limit of 10B concentration in tumor cells is less than 1·10-3 ppm under our experimental conditions which permits the quantitative determination of 10B in a small number of boronated tumor cells (105/ml = ca. 0.1 mg). Boron quantities in tumor cells determined were well compatible with the tumor cell killing effects of boron neutron capture therapy. 相似文献
49.
Satoshi Ikeda 《Annalen der Physik》1987,499(8):558-562
Some structural considerations are made on the Finslerian gravitational field: A Finslerian metrical structure such as gλχ(x, y) = γλχ(x) + hλχ(x, y) is proposed, where γλχ denotes the Riemann metric of Einstein's gravitational field, while hλχ the Finsler metric induced by the Riemann metric hij(y) of the internal field; The intrinsic behaviour of the internal variable y, which is expressed as ?i = K(x, y) yj in the internal field, is grasped by the Finslerian parallelism δyi (=0), which is reflected in the spatial structure of the external gravitational field by the mapping relation δyχ = e(x) δyi. The whole metrical Finsler connection D for gλχ(i.e., Dgλχ = 0) is determined by taking account of the intrinsic behaviour δyχ. 相似文献
50.