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101.
Based on the hydrodynamic model theory and the transfer-matrix-method, we have reexamined the reflection properties by taking account of damping effects to the system of the metallic superlattice for the S-polarized soft X-rays and extreme ultraviolet. Fot the normal incidence, we find that the reflection intensity spectxm will decline monotonously with the increasing of the retardation, but for the regions of the higher frequencies and the smaller grazing angles, the damping effects could be neglected. 相似文献
102.
103.
M. S. Nechaev I. V. Borisova N. N. Zemlyanskii D. N. Laikov Yu. A. Ustynyuk 《Russian Chemical Bulletin》2000,49(11):1823-1830
The structures of 6,6-dimethyl-6-silafulvene C5H4SiMe2 (3), its donor-acceptor complex with ammonia. C5H4SiMe2·NH3, dimethylfulvene, a number of cyclopentadienylides, methylenetrimethylphosphorane (6), and silicon-containing organophosphorus betaine−C5H4SiMe2CH2PMe3
+ (13), the product of nucleophilic addition of6 to3, were calculated using the density functional approach. For compound13, the potential energy minimum corresponds to the conformation withgauche-arrangement of the cyclopentadienyl anionie and trimethylphosphonium cationic centers and a C−Si−C−P dihedral angle of 30.5°,
which is due to the Coulomb attraction between these centers. According to calculations, betaine13 is rather stable toward decomposition into3 and6 (ΔH
o=42 kcal mol−1, ΔG
Δ=30 kcal mol−1). The main channel of thermal decomposition of compound13 involves an intramolecular nucleophilic substitution, which proceeds with elimination of trimethylphosphine and results in
1,1-dimethyl-1-silaspiro[2,4]hepta-4,6-diene, which then undergoes a ready and irreversible isomerization into 6,6-dimethyl-6-silabicyclo[3.2.0]hepta-1,3-diene
owing to the [1.5]-sigmatropic shift of the C−Si bond.
For Part 4, see Ref. 1.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1850–1857, November, 2000. 相似文献
104.
用Hartrce-Fock-Relativistic(HFR)自洽场方法,计算类锂铝离子1s^2nl(n=2~7,l=0~5),1snln’l’(n,n’=2~3,l,l’=0~2)各能级值,电偶极跃迁谱线的光谱线性质(波长、振子强度和跃迁几率),其波长计算值和现有文献结果符合得较好。特别是实验中已观察到的软X射线激光跃迁(3d-4f,3d-5f)的波长值与我们的计算值符合得也很好。 相似文献
105.
N. A. Ustynyuk T. V. Filatova V. N. Vinogradova L. I. Leont'eva O. V. Semeikin L. M. Epshtein E. S. Shubina L. N. Saitkulova E. V. Bakhmutova A. L. Chistyakov I. V. Stankevich 《Russian Chemical Bulletin》1999,48(6):1165-1173
The main regularities of the reactions of 1-haloalkynes RC≡CX with carbonylmetallate anions [(η5-C5R′5)(CO)3M]− (R′ = H (1–3),, M=Cr (1), M=Mo (2), or M=W (3); R′ =Me (4–6), M=Cr (4), M=Mo (5), or M=W (6) were revealed. It was established that the first stage of the reactions of anions1–6 with bromo- or iodoalkynes RC≡CX (X=Br or I) involved the transfer of the halogen atom from the sp-hybridized carbon atom
to the transition metal atom to form carbonyl halides [(η5-C5R′5)(CO)3MX. To the contrary, the reactions of anions1–6 with chloroalkynes RC≡CCl proceeded selectively as a nucleophilic substitution at the unsaturated carbon atom, the reaction
rate being governed by the nucleophilicity of the carbonylmetallate anions and the electron-withdrawing ability of the R group.
These reaction paths are consistent with the structures of the lowest unoccupied molecular orbitals (LUMO) in the PhC≡CX molecules
(X=Cl, Br, or I) calculated by the MNDO/PM3 method. In the case of the reactions of 1-chloroheptyne-1 C1C≡CC5H11
n, anions1–3 appeared to be insufficiently nucleophilic, but these reactions can be performed as cross-coupling of the carbonylmetallate
anions with chloroalkynes catalyzed by palladium complexes.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1176–1184, June, 1999. 相似文献
106.
合成了一种有机-无机介孔二氧化硅杂化材料(SBA-15-Tpy),通过透射电镜显微镜、X射线衍射、热重分析和N_2吸附-解吸曲线对其进行表征,并基于该材料建立了在水中对Cu2+和Co2+的选择性识别。研究表明,SBA-15-Tpy与Cu2+和Co2+结合后会分别在800 nm和510 nm处产生新的吸收峰,加入其它金属离子后不发生明显的吸收峰值变化。在最优条件下,检测Cu2+和Co2+的线性范围分别为2.0~200.0μmol/L和10.0~200.0μmol/L,检出限分别为0.48μmol/L和4.28μmol/L。将上述方法用于江水中Cu2+和Co2+的测定,回收率在96.0%~108.5%之间。 相似文献
107.
108.
Interval exchange transformations (IETs) are piecewise isometries of the interval, obtained permuting a certain number of
subintervals. We give a condition on IETs in the special subclass of IETs with periodic Rauzy-Veech cocycle which guarantees
weak mixing, i.e. the continuity of the spectrum. The proof involves the study of the associated spectral measures. The condition
can be checked explicitly by computing a certain Galois group of a field related to the Ravzy-Veech cocycle. Explicit examples
of weakly mixing IETs are constructed in the Appendix.
*Dedicated to the memory of F.A. Berezin 相似文献
109.
Yu.K. Grishin V.A. Roznyatovsky Yu.A. Ustynyuk S.N. Titova G.A. Domrachev G.A. Razuvaev 《Polyhedron》1983,2(9):895-899
31P, 195Pt and 199Hg NMR spectra of complex (PPh3)2Pt(HgGePh3)(GePh3) (I) have been studied. The spectra at temperatures below ?40°C prove that (I) is a cis-isomer with the square-planar coordination of the Pt atom. The reversibility of temperature dependences of spectra, insensitivity of line shape to the solvent, concentration and presence of free phosphine establish the fluxional behaviour of (I). The activation parameters of the intramolecular rearrangement which is realized, most probably, through a digonal twist, are: Δ≠298 = 51.5 ± 2.9 kJ/mol, ΔH≠ = 59.3 ± 2.9 kJ/mol, ΔS≠ = 26.2 ± 9.7 J/mol. K. 相似文献
110.
V. N. Baidin Yu. V. Chizhov M. M. Timoshenko Yu. A. Ustynyuk I. I. Kritskaya 《Russian Chemical Bulletin》1981,30(12):2362-2364
Conclusion The He (I) photoelectronic spectra of some organomercury compounds of the vinyl type were studied and the nature of the electronic effects in these molecules was discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2831–2834, December, 1981. 相似文献