全文获取类型
收费全文 | 84148篇 |
免费 | 499篇 |
国内免费 | 401篇 |
专业分类
化学 | 28967篇 |
晶体学 | 871篇 |
力学 | 6822篇 |
数学 | 32387篇 |
物理学 | 16001篇 |
出版年
2022年 | 59篇 |
2021年 | 61篇 |
2020年 | 77篇 |
2019年 | 99篇 |
2018年 | 10480篇 |
2017年 | 10292篇 |
2016年 | 6149篇 |
2015年 | 943篇 |
2014年 | 429篇 |
2013年 | 611篇 |
2012年 | 4106篇 |
2011年 | 10840篇 |
2010年 | 5816篇 |
2009年 | 6222篇 |
2008年 | 6961篇 |
2007年 | 9130篇 |
2006年 | 632篇 |
2005年 | 1655篇 |
2004年 | 1836篇 |
2003年 | 2254篇 |
2002年 | 1267篇 |
2001年 | 335篇 |
2000年 | 364篇 |
1999年 | 229篇 |
1998年 | 249篇 |
1997年 | 230篇 |
1996年 | 283篇 |
1995年 | 164篇 |
1994年 | 139篇 |
1993年 | 148篇 |
1992年 | 109篇 |
1991年 | 116篇 |
1990年 | 88篇 |
1989年 | 93篇 |
1988年 | 102篇 |
1987年 | 102篇 |
1986年 | 96篇 |
1985年 | 132篇 |
1984年 | 137篇 |
1983年 | 78篇 |
1982年 | 129篇 |
1981年 | 122篇 |
1980年 | 124篇 |
1979年 | 125篇 |
1978年 | 105篇 |
1977年 | 76篇 |
1976年 | 81篇 |
1975年 | 60篇 |
1974年 | 57篇 |
1973年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
1.
2.
3.
4.
Christiane Albrecht 《Analytical and bioanalytical chemistry》2008,390(5):1223-1224
5.
6.
Chengzhi Qi Mingyang Wang Qihu Qian Jianjie Chen 《Moscow University Mechanics Bulletin》2008,63(5):113-121
The formation mechanisms for the structural hierarchy in geological media are discussed. It is shown that the formation of such a hierarchy is caused by certain external and internal circumstances. The first ones consist in the fact that, because of external actions, the Earth’s poles continuously execute the translational and rotational motions responsible for a regular structure of rock fracture and for the appearance of the scale factor √2. The second ones consist in the fact that, under the action of many random factors and because of external actions, during the formation of geological media there appear dissipative structures and, hence, some self-similar fractal structures are formed. 相似文献
7.
Hiroshi Maruyama Tadao Ishii Naruhiko Bamba Hironobu Maeda Akihisa Koizumi Yuzo Yoshikawa Hitoshi Yamazaki 《Physica C: Superconductivity and its Applications》1989,160(5-6):524-532
The temperature dependence of the extended X-ray absorption fine structure (EXAFS) is studied in the high Tc superconductors, YBa2Cu3O7−δ. The measurements were done at the Cu K-edge for samples of two orthorhombic phases (Tc≈90 K and ≈58 K, respectively) and a nonsuperconducting tetragonal phase. Interatomic distances and mean square relative displacements σ2 for Cu-O bonds are determined by the least squares refinement. The results indicate that values of σ2 increase near Tc for both the orthorhombic samples. It is concluded that this anomalous behavior related to Tc is caused by an anomalous vibration of oxygen atoms in the Ba-O layer. Changes in the Cu-O distances from 300 to 20 K are not found. 相似文献
8.
Howard Robinson 《Acta Analytica》2005,20(3):7-10
Nicholas Nathan tries to resist the current version of the causal argument for sense-data in two ways. First he suggests that,
on what he considers to be the correct re-construction of the argument, it equivocates on the sense of proximate cause. Second
he defends a form of disjunctivism, by claiming that there might be an extra mechanism involved in producing veridical hallucination,
that is not present in perception. I argue that Nathan’s reconstruction of the argument is not the appropriate one, and that,
properly interpreted, the argument does not equivocate on proximate cause. Furthermore, I claim that his postulation of a
modified mechanism for hallucinations is implausibly ad hoc. 相似文献
9.
Hiroshi Noguchi Masanori Ueda Yoshinobu Baba Masako Takasu 《Journal of Polymer Science.Polymer Physics》2003,41(12):1316-1322
The electrophoresis of DNA chains in uncrosslinked polymer solutions with a Brownian dynamics simulation with an anisotropic friction tensor was analyzed. According to the degree of anisotropy, three types of migration behavior are obtained: fluctuation without or with periodicity between U‐shaped and compact conformations, or migration with linear conformation. We found good agreement between our simulation results and the direct observations of DNA by fluorescence microscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1316–1322, 2003 相似文献
10.
Xinyu Chen Yoshiro Oro Kenta Tanaka Norimichi Takenaka Hiroshi Bandow 《Analytical sciences》2004,20(7):1019-1023
A new stripping coil for the collection of nitrogen dioxide (NO2) has been developed to increase its versatility and efficiency. Nitrogen dioxide measurements based on quantitative collection through a reaction coil into an alkaline solution has been examined. Nitrogen dioxide is collected in a 0.1 N NaOH solution. This collection system has an efficiency of nearly 100%. The absorbed nitrogen dioxide has been measured by fluorescence detection with sub-ppbv detection limits. The excitation wavelength at 360 nm and the produced emission wavelength at 405 nm were suitable for nitrite ion measurements. 相似文献