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131.
Experimental and Theoretical Study of an Intramolecular CF3‐Group Shift in the Reactions of α‐Bromoenones with 1,2‐Diamines 下载免费PDF全文
Dr. Vasily M. Muzalevskiy Prof. Dr. Yury A. Ustynyuk Dr. Igor P. Gloriozov Dr. Vyacheslav A. Chertkov Dr. Alexander Yu. Rulev Dr. Evgeniy V. Kondrashov Dr. Igor A. Ushakov Alexey R. Romanov Prof. Dr. Valentine G. Nenajdenko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16982-16989
The reactions of trifluoromethylated 2‐bromoenones and N,N′‐dialkyl‐1,2‐diamines have been studied. Depending on the structures of the starting compounds, the formation of 2‐trifluoroacetylpiperazine or 3‐trifluoromethylpiperazine‐2‐ones was observed. The mechanism of the reaction is discussed in terms of multistep processes involving sequential substitution of bromine in the starting α‐bromoenones and intramolecular cyclization of the captodative aminoenones as key intermediates to form the target heterocycles. The results of theoretical calculations are in perfect agreement with the experimental data. The unique role of the trifluoromethyl group in this reaction is demonstrated. 相似文献
132.
133.
BIJIN XIONG SHIPENG ZHU YING FAN HUILIN LI MEIWU SHI YA CAO 《Journal of Macromolecular Science: Physics》2013,52(4):630-641
Hydrophobic poly(ethylene terephthalate) (PET) was prepared by reactive blending of PET with double epoxy groups modified polysiloxane (diepsi) or multiepoxy groups modified polysiloxane (multiepsi). The structure of the modified PET was characterized by 1H NMR and intrinsic viscosity. The grafted ratio of diepsi and multiepsi was 1.3 and 0.03 wt%, respectively. With the introduction of diepsi and multiepsi to PET, the water contact angle of modified PET increased from 73° to a maximum of 106°, showing the good hydrophobicity of the modified PET. The samples of modified PET were washed with different solvents and their water contact angles did not significantly decrease, indicating good durability of the hydrophobicity. Moreover, the films of modified PET prepared by solution casting (phenol and 1, 1, 2, 2-tetrachloroethane mixed solution) showed excellent hydrophobicity with the contact angle 151°. Scanning electron microscopy images showed the surface of the modified PET films to be rougher than those of unmodified PET because the introduction of polysiloxane to PET resulted in phase separation during the solvent evaporation process. 相似文献
134.
We obtain the grand potential and the associated distribution functions for a system of hard rods on a line of finite length. These functions are shown to be related to those of a semi-infinite system bounded by one hard wall. It follows that the contact values of the density and distribution functions at the walls of the finite system are related to those at the wall of the semi-infinite system, and that the force on the walls is the density at contact. We obtain also the density and distribution functions for a system with repeating boundary conditions, which are also expressible in terms of those of the finite and semi-infinite systems. 相似文献
135.
Abbasi YA Shahida S. Ali A. Khan MH Khan MI 《Journal of Radioanalytical and Nuclear Chemistry》2019,320(2):273-282
The extraction behavior of Nd(III) and Eu(III) with 0.05 mol dm−3 furosemide in benzyl alcohol as single acidic extractant and then with equimolar (0.05 mol dm−3) synergic mixture of furosemide as acidic extractant and tribenzylamine as neutral donor in benzyl alcohol has been studied from aqueous solutions of pH 1 to 6. The effect of various parameters and of various cations and anions on the extraction of these metal ions was investigated. The composition of the extracted adducts was determined by slope analysis method that came out to be [(M(FS)2)+ (CH3COO)−] and [M(FS)3·3TBA] where M = Nd(III) and Eu(III).
相似文献136.
137.
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
138.
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
139.
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
140.
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