全文获取类型
收费全文 | 497篇 |
免费 | 10篇 |
专业分类
化学 | 271篇 |
晶体学 | 19篇 |
力学 | 7篇 |
数学 | 103篇 |
物理学 | 107篇 |
出版年
2020年 | 9篇 |
2019年 | 4篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 26篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 21篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1927年 | 4篇 |
排序方式: 共有507条查询结果,搜索用时 31 毫秒
101.
102.
Dietmar Appelhans Hartmut Komber Ralf Kirchner Jürgen Seidel Chih‐Feng Huang Dieter Voigt Dirk Kuckling Feng‐Chih Chang Brigitte Voit 《Macromolecular rapid communications》2005,26(8):586-591
Summary: Polypeptide‐shelled poly(propylene imine) dendrimers were realized by ring‐opening polymerization of α‐amino acid N‐carboxyanhydrides, initiated by dendrimers as core molecules. Polypeptides with 2nd generation core were used as model compounds to investigate interior complexes between metal ion and surface‐modified dendrimers. Micro‐calorimetric measurements outlined the formation of approximate 1:1 complexes between CuII and polypeptide‐shelled dendrimers and the influence of polypeptide chain compositions on differential molar heats of complexation.
103.
K. Fischer D. Linzen E. Sinn H. Stieff F. Voigt 《Crystal Research and Technology》1979,14(12):1521-1524
More Precise knowledge of the growth mechanism of garnets in form of epitaxial layers or single crystals in high temperature solutions on the base of trivalent oxides Me2O3 in PbO B2O3 solvent is desirable. Data of physicochemical properties of the melts especially density, shear viscosity, and electrical conductivity and their dependence on the temperature are useful in endeavour to recognize the structural principles of oxidie melts. Therefore as a first step the binary system PbO Ga2O3 was investigated to understand the influence of the Ga component on a complete mixed garnet solution, for instance (Y, Sm)3 (Fe, Ga)5O12 in PbO B2O3 solvent. 相似文献
104.
Pardes Habib Jennifer Jung Gina Maria Wilms Alma Kokott-Vuong Shahin Habib Jrg B. Schulz Aaron Voigt 《Experimental & molecular medicine》2021,53(2):264
Hypoxia is an underlying pathophysiological condition of a variety of devastating diseases, including acute ischemic stroke (AIS). We are faced with limited therapeutic options for AIS patients, and even after successful restoration of cerebral blood flow, the poststroke mortality is still high. More basic research is needed to explain mortality after reperfusion and to develop adjunct neuroprotective therapies. Drosophila melanogaster (D.m.) is a suitable model to analyze hypoxia; however, little is known about the impacts of hypoxia and especially of the subsequent reperfusion injury on the behavior and survival of D.m. To address this knowledge gap, we subjected two wild-type D.m. strains (Canton-S and Oregon-R) to severe hypoxia (<0.3% O2) under standardized environmental conditions in a well-constructed hypoxia chamber. During posthypoxic reperfusion (21% O2), we assessed fly activity (evoked and spontaneous) and analyzed molecular characteristics (oxidative stress marker abundance, reactive oxygen species (ROS) production, and metabolic activity) at various timepoints during reperfusion. First, we established standard conditions to induce hypoxia in D.m. to guarantee stable and reproducible experiments. Exposure to severe hypoxia under defined conditions impaired the climbing ability and reduced the overall activity of both D.m. strains. Furthermore, a majority of the flies died during the early reperfusion phase (up to 24 h). Interestingly, the flies that died early exhibited elevated activity before death compared to that of the flies that survived the entire reperfusion period. Additionally, we detected increases in ROS and stress marker (Catalase, Superoxide Dismutase and Heat Shock Protein 70) levels as well as reductions in metabolic activity in the reperfusion phase. Finally, we found that changes in environmental conditions impacted the mortality rate. In particular, decreasing the temperature during hypoxia or the reperfusion phase displayed a protective effect. In conclusion, our data suggest that reperfusion-dependent death might be associated with elevated temperatures, predeath activity, and oxidative stress.Subject terms: Stroke, Molecular neuroscience 相似文献
105.
We show that for every Borel-measurable mapping Δ: [ω]ω → there exists A ∈ [ω]ω and there exists a continuous mapping Γ: [A]ω → [A]?ω with Γ(X) ? X such that for all X, Y ∈ [A]ω it follows that Δ(X) = Δ(Y) if Γ(X) = Γ(Y). In a sense, this is generalization of the Erdös-Rado canonization theorem 相似文献
106.
107.
108.
109.
110.
Bernd Voigt 《Journal of Combinatorial Theory, Series A》1985,40(2):349-376
We present an abstract framework for canonizing partition theorems. The concept of attribute functions and of diversification allows us to establish a canonizing product theorem, generalizing previous results of [19.], 71–83] for the situation of Ramsey's theorem. As applications we mention a canonizing product theorem for arithmetic progressions and for finite geometric arguesian lattices. We show that finite sets and finite vector spaces have the diversification property. Along these lines, iterated versions of the [6.], 249–255] and its q-analogue for finite vector spaces [[24.], 219–239] are derived. 相似文献