全文获取类型
收费全文 | 94830篇 |
免费 | 3440篇 |
国内免费 | 2766篇 |
专业分类
化学 | 36362篇 |
晶体学 | 978篇 |
力学 | 7909篇 |
综合类 | 160篇 |
数学 | 33633篇 |
物理学 | 21994篇 |
出版年
2024年 | 62篇 |
2023年 | 377篇 |
2022年 | 638篇 |
2021年 | 669篇 |
2020年 | 748篇 |
2019年 | 656篇 |
2018年 | 10880篇 |
2017年 | 10660篇 |
2016年 | 6786篇 |
2015年 | 1636篇 |
2014年 | 1284篇 |
2013年 | 1509篇 |
2012年 | 5336篇 |
2011年 | 12017篇 |
2010年 | 6652篇 |
2009年 | 7003篇 |
2008年 | 7694篇 |
2007年 | 9702篇 |
2006年 | 1251篇 |
2005年 | 2144篇 |
2004年 | 2182篇 |
2003年 | 2509篇 |
2002年 | 1558篇 |
2001年 | 709篇 |
2000年 | 677篇 |
1999年 | 602篇 |
1998年 | 504篇 |
1997年 | 439篇 |
1996年 | 533篇 |
1995年 | 400篇 |
1994年 | 347篇 |
1993年 | 293篇 |
1992年 | 243篇 |
1991年 | 220篇 |
1990年 | 182篇 |
1989年 | 169篇 |
1988年 | 166篇 |
1987年 | 124篇 |
1986年 | 119篇 |
1985年 | 89篇 |
1984年 | 73篇 |
1983年 | 62篇 |
1982年 | 54篇 |
1981年 | 56篇 |
1980年 | 53篇 |
1979年 | 46篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
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
5.
The reversible nonlinear conduction (RNC) in of high‐density polyethylene/acetylene carbon black composites with different degrees of crosslinking was studied above room temperature and below the melting point of high‐density polyethylene (HDPE). The experimental current density‐electric field strength curves can be overlapped onto a master curve, suggesting that the microscopic mechanisms for the appearance of RNC exist regardless of the ambient temperature and the crosslinking degree of the HDPE matrix. The relationship between the crossover current density and the linear conductivity can be explained in the framework of the dynamic random‐resistor‐network model. According to these results, two electron‐tunneling models are suggested to interpret the microscopic conduction behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1212–1217, 2004 相似文献
6.
Nylon‐6/glass‐fiber (GF)/liquid‐crystalline‐polymer (LCP) ternary blends with different viscosity ratios were prepared with three kinds of nylon‐6 with different viscosities as matrices. The rheological behaviors of these blends were characterized with capillary rheometry. The morphology was observed with scanning electron microscopy and polarizing optical microscopy. This study showed that although LCP did not fibrillate in binary nylon‐6/LCP blends, LCP fibrillated to a large aspect ratio in some ternary blends after GF was added. The addition of 5 wt % LCP significantly reduced the melt viscosity of nylon‐6/GF blends to such an extent that some nylon‐6/GF/LCP blends had quite low viscosities, not only lower than those of neat resins and nylon‐6/GF blends but also lower than those of corresponding nylon‐6/LCP blends. The mutual influence of the morphology and rheological properties was examined. The great reduction of the melt viscosity was considered the result of LCP fibrillation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1619–1627, 2004 相似文献
7.
Based on the complexation between proteins and Cu(II) coupled with the time-resolved chemiluminescence (CL) technique, a highly sensitive and quantitative assay for measuring proteins in solution is described. The complexes of proteins with Cu(II) have a strongly catalytic effect on the luminol-H2O2 CL reaction. Because the CL emission produced by the complexes is much more long-lived than that by Cu(II), the CL signals originating from proteins can be easily identified and measured with a time-resolved technique. On this basis, bovine albumin fraction V (BAF V) can be quantitatively determined in the range of 0.01 - 5.0 microg/ml with a detection limit of 5.8 ng/ml. The results show that the proposed assay exhibits a small variation in the response values for the same amount of different proteins, as compared to the Lowry as well as Bradford assays. The CL assay has also been studied for the detection of immobilized proteins. 相似文献
8.
A hybrid cluster complex, formed by chelating a chromogenic ligand to a [2Fe-2S] cluster, sensitively exhibited differential colorimetric responses towards Hg2+, Cd2+, Cr3+, Pb2, Sn2+, Cu2+, Zn2+, Fe3+ and Co2+ in water at physiological pH. Speciation of some of these metal elements, such as Cr(III) and Sn(IV), was also studied by UV/Vis absorption. 相似文献
9.
10.