全文获取类型
收费全文 | 1350篇 |
免费 | 38篇 |
国内免费 | 5篇 |
专业分类
化学 | 922篇 |
晶体学 | 3篇 |
力学 | 33篇 |
数学 | 192篇 |
物理学 | 243篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 10篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 22篇 |
2016年 | 30篇 |
2015年 | 34篇 |
2014年 | 35篇 |
2013年 | 83篇 |
2012年 | 55篇 |
2011年 | 80篇 |
2010年 | 46篇 |
2009年 | 45篇 |
2008年 | 90篇 |
2007年 | 80篇 |
2006年 | 81篇 |
2005年 | 87篇 |
2004年 | 79篇 |
2003年 | 51篇 |
2002年 | 49篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 22篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 24篇 |
1983年 | 23篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1973年 | 10篇 |
1954年 | 4篇 |
排序方式: 共有1393条查询结果,搜索用时 0 毫秒
161.
Klingstedt T Aslund A Simon RA Johansson LB Mason JJ Nyström S Hammarström P Nilsson KP 《Organic & biomolecular chemistry》2011,9(24):8356-8370
Molecular probes for selective identification of protein aggregates are important to advance our understanding of the molecular pathogenesis underlying protein aggregation diseases. Here we report the chemical design of a library of anionic luminescent conjugated oligothiophenes (LCOs), which can be utilized as ligands for detection of protein aggregates. Certain molecular requirements were shown to be necessary for detecting (i) early non-thioflavinophilic protein assemblies of Aβ1-42 and insulin preceding the formation of amyloid fibrils and (ii) for obtaining distinct spectral signatures of the two main pathological hallmarks observed in human Alzheimer's diease brain tissue (Aβ plaques and neurofibrillary tangles). Our findings suggest that a superior anionic LCO-based ligand should have a backbone consisting of five to seven thiophene units and carboxyl groups extending the conjugated thiophene backbone. Such LCOs will be highly useful for studying the underlying molecular events of protein aggregation diseases and could also be utilized for the development of novel diagnostic tools for these diseases. 相似文献
162.
Per Malmberg Eva Jennische Daniel Nilsson Håkan Nygren 《Analytical and bioanalytical chemistry》2011,399(8):2711-2718
The use of high-resolution, imaging TOF-SIMS is described and examples are made to demonstrate the application of the method
in medical research. Cytochemistry by TOF-SIMS is shown by localization of diacylglycerol (DG) in cryostat sections of hyaline
cartilage and by localization of corticosterone in cryostat sections of the adrenal gland cortex. Quantitative measurements
and comparison of groups is shown by comparing the lipid content of adipose tissue from two mouse strains, transgenic mouse
expressing the FOXC2 gene and wild-type controls. Finally, biopsies made for histopathological diagnosis of infantile reversible
cytochrome c oxidase deficiency myopathy were analyzed in order to define the chemical content of areas showing a pathological
structure in the light microscope. The use of high-resolution, imaging TOF-SIMS in medical research allows analysis of intact
tissue and probe-free localization of specific target molecules in cells and tissues. The TOF-SIMS analysis is not dependent
on penetration of reagents into the sample and also independent of probe reactivity such as cross-reactivity or background
staining. The TOF-SIMS method can be made quantitative and allows for analysis of specific target molecules in defined tissue
compartments. 相似文献
163.
Antti Perälä 《Integral Equations and Operator Theory》2011,71(1):113-128
We study Toeplitz operators between analytic Bloch-type spaces of the unit disk. We construct suitable classes of distributions
that generate bounded Toeplitz operators between these spaces. The classes are naturally connected to the corresponding results
in the reflexive Bergman space setting and previously known results on A
1 and the Bloch space. We also study distributional symbols satisfying logarithmic BMO-condition. In addition, sufficient compactness
criteria are provided. 相似文献
164.
Xhanari K Syverud K Chinga-Carrasco G Paso K Stenius P 《Journal of colloid and interface science》2011,356(1):58-62
The nature of layers formed by cellulose nanofibrils that had been surface modified (hydrophobized) at the oil/water (o/w) interface was investigated. The aim of the study was to clarify the mechanism underlying the excellent ability of these nanoparticles to stabilize emulsions. Layers of hydrophobized nanofibrillated cellulose spread at the o/w interface were deposited on glass slides by the Langmuir-Blodgett deposition technique. Overall evaluation of layer structures was performed by image analysis based on a Quadtree decomposition of images obtained from a flatbed scanner. A more detailed characterization of the layer structures was performed by Atomic Force Microscopy (AFM), and Field-Emission Scanning Electron Microscopy (FE-SEM). The results show that nanofibrils that were able to stabilize emulsions occur as single, dispersed fibrils or form large, network-like aggregates at the o/w interface. Fibrils that were insufficiently hydrophobized and therefore did not stabilize emulsions were only partially deposited and formed small, compact aggregates. We conclude that it is likely that the network formation is the main mechanism by which the fibrils prevent coalescence of emulsion droplets. 相似文献
165.
166.
167.
A. D. Bauer C. S. Ford A. K. Church J. H. Wilson P. A. Popow J. Davidsohn G. Knigge E. Walter F. Wittka E. J. Better K. Scheringa Per Ekwall H. Janistyn P. Wulff W. Poethke W. Bleyberg H. Lettner J. W. Mc Bain H. E. Martin und E. L. Lederer 《Fresenius' Journal of Analytical Chemistry》1936,104(7-8):306-316
Ohne Zusammenfassung 相似文献
168.
Jarl B. Rosenholm Marja-Riitta Hakala Per Stenius 《Molecular Crystals and Liquid Crystals》2013,570(3-4):285-305
The relative partial molar enthalpies of the components in the system N-pentanol-sodium N-octanoate-water (C5OH-NaC8-H2O) have been determined in the lamellar (D-) and hexagonal (E-) liquid crystalline phases formed in this system at 25°C. The enthalpies are correlated with Bragg spacings and earlier nmr studies. They indicate that (a) the minimum amount of water needed to hydrate the polar groups limits the region of existence of both D- and E-phase towards low water contents, (b) the interaction between -OH and -COO is especially important in stabilizing the D-phase containing large amounts of water, (c) the Bragg spacings and the enthalpies both change their concentration dependence markedly when the maximum amount of water that can be bound by primary hydration of the polar groups and the counter ions in the D-phase is exceeded, (d) enthalpies of transition from one phase to another are small compared to enthalpy changes with composition within the phases; the same holds for Bragg spacings. Hence, the composition of the sample (above all, the mole fraction of NaC8) is more important than the phase structure in determining these properties. It is obvious that further studies of enthalpies in similar systems can give important information on the factors governing phase stabilities and structural changes within the phases. 相似文献
169.
Allylic thioethers of the general structure 1 underwent E/Z isomerization during both basic and acidic hydrolysis of the ester moiety at the remote end of the molecule. The isomerization was dependent on the substitution of the allylic moiety. The presence of a 5-membered heterocycle on the double bond supported the isomerization. However, analogous oxy-ethers were stable. 相似文献
170.
Mohamed Ghazzali Lars
hrstrm Per Lincoln Vratislav Langer 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(7):m243-m245
The title compound, [Ru(C12H8N2)3]2[Fe(NCS)4](ClO4)2, crystallizes in a tetragonal chiral space group (P41212) and the assigned absolute configuration of the optically active molecules was unequivocally confirmed. The Δ‐[RuII(phen)3]2+ complex cations (phen is 1,10‐phenanthroline) interact along the 41 screw axis parallel to the c axis, with an Ru...Ru distance of 10.4170 (6) Å, and in the ab plane, with Ru...Ru distances of 10.0920 (6) and 10.0938 (6) Å, defining a primitive cubic lattice. The Fe atom is situated on the twofold axis diagonal in the ab plane. The supramolecular architecture is supported by C—H...O interactions between the [RuII(phen)3]2+ cation and the disordered perchlorate anion. This study adds to the relatively scarce knowledge about intermolecular interactions between [Ru(phen)3]2+ ions in the solid state, knowledge that eventually may also lead to a better understanding of the solution state interactions of this species; these are of immense interest because of the photochemical properties of these ions and their interactions with DNA. 相似文献