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排序方式: 共有382条查询结果,搜索用时 15 毫秒
1.
Bo-Hao Chen Jun-Jia Xu Wei-Ren Lai Chung-Kai Chang Jeng-Lung Chen Jyh-Fu Lee Jin-Ming Chen Hwo-Shuenn Sheu Jey-Jau Lee Yoshiki Kubota Ming-Hsi Chiang Yasutaka Kitagawa Yu-Chun Chuang I-Jui Hsu 《中国化学会会志》2023,70(5):1187-1199
Two cobalt(II) halide complexes with 1,2,4-triazole as a ligand were synthesized. Their structures were determined by extended x-ray absorption fine structure (EXAFS) and powder x-ray diffraction (XRD). Both complexes [Co(Htrz)Cl2]n ( 1 ) and {[Co(Htrz)2(trz)]BF4}n ( 2 ) form one-dimensional polymeric chain and the distances of Co⋯Co are 3.3521(2) Å and 3.8629(2) Å, respectively. The Htrz and Cl− are bridging ligands to connect two Co(II) ions in 1 , and the local environment of Co site is in a distorted octahedron with {CoN2Cl4} core. In complex 2 , two Htrz and one trz are bridging ligands to connect two Co(II) ions, and the local geometry of Co is in a pseudo octahedron with {CoN6} core. The analysis of Co LII,III-edge XAS indicates that the Co(II) of both complexes are at high spin state with t2g5eg2 configuration and the crystal field strength (10Dq) is about 1.2 eV. The broken-symmetry DFT calculations indicate that antiferromagnetic coupling state of Co⋯Co is the most stable state in both complexes; and the coupling constants of 1 and 2 are −0.32 cm−1 and −3.70 cm−1, respectively. Based on the distances of Co⋯Co and coupling constants, such antiferromagnetic interaction is achieved through triazole ligands. 相似文献
2.
Characterization of Novel Aminobenzylcantharidinimides and Related Imides by Proton NMR Spectra and Their Effects on NO Induction 下载免费PDF全文
Ing‐Jy Tseng Pen‐Yuan Lin Shiow‐Yunn Sheu Wan‐Ni Tung Ching‐Tung Lin Mei‐Hsiang Lin 《中国化学会会志》2015,62(1):59-63
Various acidic anhydrides including cantharidin were converted into corresponding aminobenzylcantharidinimide 3a and analogous imides 3b~k (at the ortho, meta, and para positions) with 35%~87% yields by reacting with aminobenzylamines and triethylamine. The two methyl side chains of cantharidinimides 3ao , 3am , and 3ap, and related imides had more than two chiral centers; the lone pair of electrons of nitrogen displayed a different chemical shift and coupling constant in H‐NMR spectra when the amino group of benzylamine was in the ortho position. These cantharidinimides had parent aniline, pyridine, and naphthalene plane structures, and the primary amine nucleophilicity and basicity might reflect the inductive electron’s negative effect on chemical shifts. We prepared cantharidinimides by heating the reactants cantharidin 1a , aliphatic and aromatic acid anhydrides, primary benzylic amines, and aniline derivatives to ca. 200 °C with 3 mL of dry toluene, and 1~2 mL of triethylamine in high‐pressure sealed tubes (Buchi glasuster 0032) to produce cantharidinimides and their analogues in good yields. The para‐aminobenzylic imides showed greater inhibition of nitric oxide (NO) synthesis by NO synthase (NOS) than did ortho‐ and meta‐aminobenzylic imides. Compound 3fp , para‐aminobenzylic norbonane‐imide, had the most potent effect on inducible NOS among the tested compounds and showed 35% inhibition. 相似文献
3.
Atallah F. Ahmed Yang Cheng Chang-Feng Dai Jyh-Horng Sheu 《Molecules (Basel, Switzerland)》2021,26(11)
Three new polyoxygenated diterpenoids with a rare 4-isopropyl-1,5,8a-trimethylperhydrophenanthrane structure of the klysimplexane skeleton, briarols A‒C (1‒3), and one eunicellin-based diterpenoid, briarol D (4), were isolated from Briareum violaceum, a gorgonian inhabiting Taiwanese waters. The chemical structures of these compounds were determined by employing extensive analyses of NMR and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Metabolites 1‒3 were found to possess the rarely found skeleton of the diterpenoid klysimplexin T. All isolated compounds showed very weak cytotoxic activity against the growth of three cancer cell lines. A plausible biosynthetic pathway for briarols A‒C from the coexisting eunicellin diterpenoid briarol D (4) was postulated. 相似文献
4.
Measurements of mean velocities, flow direction, velocity fluctuations and Reynolds shear stress were made with a split film probe of hot wire anemometer to investigate the interactions created by two air jets issuing from two identical plane inclined nozzles. The reverse flow was detected by using the split film probe and observed by flow visualization. Experimental results with an inclined angle of 9° are presented in the paper. Some experimental results with an inclined angle of 27° are presented to investigate the effect of inclination on the flow field.Mean velocities approach self-preservation in both the converging region and the combining region. Velocity fluctuations and Reynolds shear stress approach self-preservation in the combining region only. The spreads of jet and the square of the decay of maximum mean velocity increase linearly as the distance from the nozzle exit increases.List of symbols
D
nozzle width
-
h
nozzle height
-
J
momentum of jet
-
J
0
momentum of jet at nozzle exit
-
M
mass flow rate
-
M
0
mass flow rate at nozzle exit
-
S
nozzle spacing
-
U, V
mean velocities in the X and Y axis respectively
-
U
m
maximum axial velocity
-
U
0
axial velocity at nozzle exit
-
u, v
velocity fluctuations in the X and Y axis respectively
-
u, v
r.m.s. of u and v
-
Reynolds shear stress
-
X, Y
Cartesian coordinates
-
X
m
, Y
m
coordinates at the location of maximum axial velocity
-
y
0.5
distance from the location of maximum axial velocity to the location where the velocity is half of maximum axial velocity
-
inclined angle
-
yY/S
-
Reynolds stress correlation coefficient
- C.P
combining point
- max
maximum value
- M.P
merging point
- o
nozzle exit plane
- V.C
vortex center 相似文献
5.
6.
Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. 相似文献
7.
Carbonyl compounds reacted with stable phosphonium ylides in D2O to give α-deuterated-α,β-unsaturated carbonyl compounds in the same flask. The chemical yield and deuterium incorporation are excellent under our procedure. The fragile group like ozonide was compatible with our reaction condition. 相似文献
8.
A particular choice of renormalization, within the simplifications provided by the non-perturbative property of Effective Locality, leads to a completely finite, non-perturbative approach to renormalized QCD, in which all correlation functions can, in principle, be defined and calculated. In this Model of renormalization, only the Bundle chain-Graphs of the cluster expansion are non-zero. All Bundle graphs connecting to closed quark loops of whatever complexity, and attached to a single quark line, provided no ‘self-energy’ to that quark line, and hence no effective renormalization. However, the exchange of momentum between one quark line and another, involves only the cluster-expansion’s chain graphs, and yields a set of contributions which can be summed and provide a finite color-charge renormalization that can be incorporated into all other QCD processes. An application to High Energy elastic pp scattering is now underway. 相似文献
9.
Long Jye Sheu 《Transport in Porous Media》2011,88(3):461-477
The onset of convection in a horizontal layer of a porous medium saturated with a viscoelastic nanofluid was studied in this
article. The modified Darcy model was applied to simulate the momentum equation in porous media. An Oldroyd-B type constitutive
equation was used to describe the rheological behavior of viscoelastic nanofluids. The model used for the viscoelastic nanofluid
incorporates the effects of Brownian motion and thermophoresis. The onset criterion for stationary and oscillatory convection
was analytically derived. The effects of the concentration Rayleigh number, Prandtl number, Lewis number, capacity ratio,
relaxation, and retardation parameters on the stability of the system were investigated. Oscillatory instability is possible
in both bottom- and top-heavy nanoparticle distributions. Results indicated that there is competition among the processes
of thermophoresis, Brownian diffusion, and viscoelasticity that causes the convection to set in through oscillatory rather
than stationary modes. Regimes of stationary and oscillatory convection for various parameters were derived and are discussed
in detail. 相似文献
10.
Jeng-Horng Sheu 《Journal of organometallic chemistry》2011,696(6):1221-1227
Group 2 bis-element sandwiches formed by homoleptic open sandwiches with formula C5H7-M-M-C5H7 and C4H4P-M-M-C4H4P (M = Be, Mg, and Ca) have been studied at the B3LYP/cc-PVDZ and BP86/6-311G(d,p) levels of theory. The predicted M-M bond distances are much shorter than in the equivalent isolated M-M dimer and indicate substantial Be-Be, Mg-Mg, and Ca-Ca bonding. An NBO analysis shows that each M-M unit contains a single covalent bond and that the unit is linked to the open pentadienyl and phospholyl ring via ionic bonds. We thus predict that these new compounds are viable synthetic targets. 相似文献