全文获取类型
收费全文 | 3607篇 |
免费 | 163篇 |
国内免费 | 33篇 |
专业分类
化学 | 2558篇 |
晶体学 | 35篇 |
力学 | 168篇 |
综合类 | 5篇 |
数学 | 475篇 |
物理学 | 562篇 |
出版年
2023年 | 22篇 |
2022年 | 79篇 |
2021年 | 162篇 |
2020年 | 94篇 |
2019年 | 111篇 |
2018年 | 117篇 |
2017年 | 94篇 |
2016年 | 173篇 |
2015年 | 142篇 |
2014年 | 149篇 |
2013年 | 353篇 |
2012年 | 243篇 |
2011年 | 261篇 |
2010年 | 179篇 |
2009年 | 149篇 |
2008年 | 160篇 |
2007年 | 162篇 |
2006年 | 120篇 |
2005年 | 104篇 |
2004年 | 94篇 |
2003年 | 84篇 |
2002年 | 81篇 |
2001年 | 50篇 |
2000年 | 58篇 |
1999年 | 21篇 |
1998年 | 30篇 |
1997年 | 18篇 |
1996年 | 34篇 |
1995年 | 24篇 |
1994年 | 25篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 23篇 |
1990年 | 25篇 |
1989年 | 18篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 29篇 |
1984年 | 26篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 16篇 |
1975年 | 16篇 |
1973年 | 8篇 |
排序方式: 共有3803条查询结果,搜索用时 656 毫秒
11.
12.
We give several equivalent characterisations of left (and hence, by duality, also of right) supported algebras. These characterisations are in terms of properties of the left and the right parts of the module category, or in terms of the classes L0 and R0 which consist respectively of the predecessors of the projective modules, and of the successors of the injective modules. 相似文献
13.
14.
Zhigang Yin Nuofu Chen Shulin Song Jun Zhong Kurash Ibrahim 《Solid State Communications》2005,135(7):430-433
Nickel-doped ZnO (Zn1−xNixO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni has a chemical valence of 2+. According to the magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn0.86Ni0.14O. We studied the electronic structure of Zn0.86Ni0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at ∼2 eV below the Fermi energy EF, which is of Ni 3d origin. No emission was found at EF, suggesting the insulating nature of the film. 相似文献
15.
Amir Abbas Matin Ramin Maleki Mir Ali Farajzadeh Khalil Farhadi Reza Hosseinzadeh Abolghasem Jouyban 《Chromatographia》2007,66(5-6):383-387
A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a
mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire and its application to the determination
of ketone bodies is described. Unlike commercial fibers, which are coated on fused silica, the coating adheres strongly to
the silver wire and is thermally stable up to 250 °C. After optimization of coating composition and microextraction conditions
the fiber was used for the analysis of acetone in human urine. 相似文献
16.
S. Franchoo F. Ibrahim F. Le Blanc M. Lebois A. Olivier C. Phan Viet B. Roussière R. Sifi D. Verney 《Hyperfine Interactions》2006,171(1-3):117-119
The availability of both a tandem deuteron beam and a linac electron beam, the latter converted into Bremsstrahlung, at the
new ALTO facility at IPN-Orsay offers a unique opportunity to compare the performance of a laser ion guide under different
regimes. The ALTO accelerator has delivered its first electron beam at the end of 2005 and a design for a gas-cell prototype
is being studied. 相似文献
17.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o287-o288
In the title compound, C18H13BrClNO3, the heterocyclic ring of the indole is distorted from planarity towards an envelope conformation. The orientations of the indole, oxetane, chloro and bromophenyl substituents are conditioned by the sp3 states of the spiro‐junction and the Cl‐attached C atoms. 相似文献
18.
Unusual Formation and Structure of a O‐Sulfinato Zinc Complex Whereas the reaction between hydrotris[(N‐xylyl)‐thioimidazolyl]borato‐zinc perchlorate ([ L· Zn‐OClO3]) and ethanethiolate under an inert atmosphere leads to the thiolate complex [ L· Zn‐SC2H5], the same reaction in air produces the sulfinato complex [ L· Zn‐O‐S(O)‐C2H5] ( 1 ). 1 is the first fully characterized sulfinato‐zinc complex. Its structure determination has confirmed the unusual coordination of the sulfinato ligand via one of its oxygen atoms. 相似文献
19.
Gas-phase thermolysis of thieno[3,2-e][1,2,4]triazines gave benzonitrile, isothiazole, pyrimidine, [1]benzothieno[2,3-d]pyrimidine and thieno[3,2-d]thiazole derivatives. A mechanism of these pyrolytic transformation was proposed. Two new and efficient syntheses of the starting thieno[3,2-e][1,2,4]triazines were reported. 相似文献
20.