全文获取类型
收费全文 | 553篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 336篇 |
晶体学 | 11篇 |
力学 | 11篇 |
数学 | 30篇 |
物理学 | 173篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 8篇 |
2020年 | 14篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 19篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 30篇 |
2012年 | 36篇 |
2011年 | 31篇 |
2010年 | 22篇 |
2009年 | 14篇 |
2008年 | 23篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 19篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2000年 | 3篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1981年 | 12篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1955年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有561条查询结果,搜索用时 15 毫秒
531.
We have measured thermoreflectance spectra of epitaxial PbS, PbSe, PbTe, and SnTe films from 0.7 to 5.6 eV, at room temperature and 77 K. Fine structures associated with the usual reflectivity peaks are observed, most of which agree in spectral position with electric field and wavelength modulation results. Δεr and Δεi have been obtained through a Kramers-Kronig analysis of our Δ R/R spectra. In the absence of experimental symmetry information, tentative assignments are made based on (1) comparison of temperature coefficients with theoretical deformation potentials, (2) comparison of δε curves with theoretical lineshapes, and (3) matching the structures with existing band structure calculations and related information. 相似文献
532.
533.
534.
535.
Rakesh Kumar Mahajan Pallavi Sood Mohinder Pal Mahajan Parvesh Singh 《Analytical sciences》2004,20(10):1423-1426
A silver ion-selective electrode was prepared with a polymeric membrane incorporating 2,6-bis-methylsulfanyl-[1,3,5]thiadiazine-4-thione as an ionophore, tri-n-butylphosphate (TBP) as a plasticizer and sodium tetraphenylborate (NaTPB) as an additive. The electrode exhibited a near-Nernstian response of 52 mV/decade over a wide linear concentration range of 1.0 x 10(-5) - 1.0 x 10(-1) M with a lower detection limit of 9.77 x 10(-6) M. The electrode exhibited excellent selectivity for silver ion over many of the alkali, alkaline-earth and transition metal ions. The electrode worked well over a wide pH range of 1.77 - 7.13. The response time of the electrode was less than 20 s. The sensor can be applied as indicator electrode for the potentiometric titration of Ag+ ions with Cl- ions. 相似文献
536.
Ohne Zusammenfassung 相似文献
537.
The basic role of the representation of the gauge group in characterizing the topological excitations of the vacuum is pointed out. For SU(N) gauge fields on a lattice, the topological excitations are monopoles in the adjoint representation of the dual group 1SU(N). This leads to a dual representation of the Yang-Mills-Higgs system in 2 + 1 dimensions. For SU(3) the deal theory in a scalar theory with discrete Weyl symmetry S3. In the presence of adjoint Higgs fields the Weyl symmetry is broken in the Higgs phase but restored by pseudo-particles in the confinement phase. 相似文献
538.
539.
Chaudhuri P Wagner R Khanra S Weyhermüller T 《Dalton transactions (Cambridge, England : 2003)》2006,(41):4962-4968
Reaction of a 1 : 1 : 1 molar ratio of NiCl(2), NaN(3) and H(2)L, a tetradentate ligand N-(2-pyridyl)methyl)-N,N-bis(2'-hydroxy-3',5'-dimethylbenzyl)amine in methanol in presence of Et(3)N results in a turquoise precipitate, which affords deep green crystals of [Ni(2)(HL)(2)(N(3))(2)]*1.5CH(2)Cl(2) (1) and [Ni(2)(HL)(2)(N(3))(2)]*H(2)O (2) upon crystallization from CH(2)Cl(2)-MeOH or THF-MeOH, respectively. Both complexes reveal distorted octahedral NiN(4)O(2) coordination environments around the Ni(ii) centers with bis(micro-1,1-azido) bridging ligands. Complex 1 displays an unprecedented small Ni-N-Ni bridge angle of 90.4 degrees , whereas 2 contains the said angle of av. 98.7 degrees lying in the usual range observed for other comparable structures. The variable-temperature magnetic susceptibility together with the variable-field, variable-temperature (VTVH) magnetization measurements discern different ground states of S(t) = 0 for 1 and S(t) = 2 for 2. The magnetic behaviours of these compounds are discussed in the context of the known bis(end-on azido) bridging dinickel(II) complexes. 相似文献
540.
Sumit Kumar Ramovatar Meena R. Paulraj 《Applied biochemistry and biotechnology》2016,180(7):1257-1275
Titanium-dioxide nanoparticles (TNP) are used in various consumable goods. Evidence has demonstrated the cytotoxicity of TNPs, but exact mechanism is yet to be elucidated. The present study has been aimed at finding out the mechanism of TNP-induced toxicity in biological system. Different doses of anatase-TNPs administrated intravenously to Wistar rats for once a week for 1 month and properties of TH cells, macrophages, cytokines secretion, oxidative damage, apoptotic pathway, and hematological and pathological changes were investigated as downstream events of TNP-mediated cytotoxicity. Result suggests that TNPs induce TH1 and TH2 response as measured by immunophenotyping (interferon gamma (IFN-γ) and interleukin (IL)-4) of TH cells, causing induction of M1 (nitric oxide (NO), nitric oxide synthase (iNOS), NF-kappaB (NF-κB), cyclooxygenase-2 (COX-2), IL-1, IL-6, and TNF-α) and M2 (Arg-1, Ym1) macrophages response. At lower dose, TH1 or M1 response counteracted by TH2 or M2 response, resulting in insignificant oxidative damage. However, with increasing dose of TNPs, the M1 response was increased over M2 response resulting in significant tissue damage. The M1-induced inflammatory response was found to cause DNA and chromosomal damage resulting apoptosis induction via upregulation of Bax/Bcl-2 ratio and subsequent loss of mitochondrial membrane potential and cyto c release in splenocytes. The TNP-led inflammatory response also causes damage at different tissue levels. 相似文献