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91.
Reaction of Trithiazyl Chloride with Titanium Tetrachloride. Crystal Structure of (S4N5)2[Ti2Cl10] In the reaction of trithiazyl chloride with titanium tetrachloride, chlorine is abstracted and the brown-yellow adduct TiCl4(N2S2) is obtained. In this compound — according to its i.r. spectrum — a N2S2 ring is bonded to the titanium via the N atoms, thus forming a polymer. As a by-product, brown crystalline (S4N5)2[Ti2Cl10] forms. Its crystal structure was determined and refined with X-ray diffraction data (R = 0.042 for 812 reflexions). It crystallizes in the monoclinic space group P21/c with two formula units per unit cell. The lattice constants are a = 670, b = 1 633, c = 1108 pm, β = 97.24°. The structure consists of S4N5⊕ cations, which are nearly equal to those in [S4N5]Cl, and [Ti2Cl10]2? anions, which are nearly identical with those in (PCl4)2[Ti2Cl10]. 相似文献
92.
Atom transfer radical polymerization conditions with copper(I) bromide/2,2′-bipyridine (Cu/2,2′-bpy) as the catalyst system were employed for the homopolymerization and random copolymerization of 1-phenoxycarbonyl ethyl methacrylate (PCMA) with methyl methacrylate (MMA). Temperature studies indicated that the polymerizations occurred smoothly in bulk at 110 °C. Poly(PCMA)(polydispersity index=1.27) homopolymer was characterized and then used as macroinitiator for increasing its molecular weight. The homopolymerization of PCMA was also carried out under free radical conditions using 2,2′-azobisisobutyronitrile as an initiator.The monomer and polymers were characterized by FT-IR and 1H and 13C-NMR techniques. The glass transition temperatures, the solubility parameters and average-molecular weights of the polymers were determined. Thermal stabilities of the polymers were given as compared with each other by using TGA curves. Thermal degradation products of poly(PCMA)s obtained by ATRP and free radical polymerization were compared with each other by using 1H-NMR technique. 相似文献
93.
Morcombe CR Gaponenko V Byrd RA Zilm KW 《Journal of the American Chemical Society》2005,127(1):397-404
(13)C CPMAS NMR has been investigated in application to protein samples with a variety of deuteration patterns. Samples were prepared with protons in either all hydrogen positions, only in the exchangeable sites, or in the exchangeable sites plus select methyl groups. CP dynamics, T(1) relaxation times, and (13)C line widths have been compared. Using ubiquitin as a model system, reasonable (1)H-(13)C CP transfer is observed for the extensively deuterated samples. In the absence of deuterium decoupling, the (13)C line widths observed for the deuterated samples are identical to those observed for the perprotio samples with a MAS rate of 20 kHz. Extensive deuteration has little effect on the T(1) of the exchangeable protons. On the basis of these observations, it is clear that there are no substantive compromises accompanying the use of extensive deuteration in the design of (1)H, (15)N, or (13)C solid-state NMR methods. 相似文献
94.
Wally L. Chang Kurt C. Frisch Kaneyoshi Ashida 《Journal of polymer science. Part A, Polymer chemistry》1989,27(11):3619-3635
Two component interpenetrating networks (IPNs) of the SIN type (simultaneous interpenetrating networks), composed of a polyisocyanurate network and a star-shaped nylon 6, were made. The overall polymerization rates and physical properties for reaction injection molding (RIM) have been studied by the quasi-adiabatic process. In order to model the actual rapid molding conditions, time versus temperature reaction profiles were measured, and the relative rates of polymerization subsequently determined from these data. 相似文献
95.
A lattice model of a symmetrical binary (AB) polymer mixture is studied, modelling the polymer chains by self-avoiding walks withN
A
=N
B
=N steps on a simple cubic lattice. If a pair of nearest neighbour sites is taken by different monomersAB orBA, an energy
ab
is won; if the pair of sites is taken by anAA or aBB pair, an energy is won, while the energy is reduced to zero if at least one of the sites of the pair is vacant. To allow enough chain mobility, 20% of the lattice sites are vacancies. In addition to local motions of the chain segments we use a novel grand-canonical simulation technique:A chains are transformed intoB chains and vice versa, keeping the chemical potential difference fixed. The phase diagram is obtained forN=4, 8,16 and 32; the critical behaviour is analysed by finite-size scaling methods. It is shown that the critical exponents are those of the Ising model (=0.32,=0.63) rather than those of the Flory-Huggins meanfield theory (==1/2). Implications of these results for real polymers are briefly discussed.Paper presented at the Frühjahrstagung 1986, Polymerphysik, der Deutschen Physikalischen Gesellschaft, Kaiserslautern, March 12–14, 1986. 相似文献
96.
Igumenova TI McDermott AE Zilm KW Martin RW Paulson EK Wand AJ 《Journal of the American Chemical Society》2004,126(21):6720-6727
Solid-state NMR 2D spectroscopy was used to correlate carbon backbone and side-chain chemical shifts for uniformly (13)C,(15)N-enriched microcrystalline ubiquitin. High applied field strengths, 800 MHz for protons, moderate proton decoupling fields, 80-100 kHz, and high magic angle sample spinning frequencies, 20 kHz, were used to narrow the most of the carbon line widths to 0.5-0.8 ppm. Homonuclear magnetization transfer was effected by matching the proton RF field to the spinning frequency, the so-called dipolar-assisted rotational resonance (DARR) (Takegoshi, K.; Nakamura, S.; Terao, T. Chem. Phys. Lett. 2001, 344, 631-637), and a mixing time of 20 ms was used to maximize the intensity of one-bond transfers between carbon atoms. This polarization transfer sequence resulted in roughly 14% transfer efficiencies for directly bonded carbon pairs and 4% transfer efficiencies for carbons separated by a third carbon. With this simple procedure, the majority of the one-bond correlations was observed with moderate transfer efficiencies, and many two-bond correlations were also observed with weaker intensities. Spin systems could be identified for more than half of the amino acid side chains, and site-specific assignments were readily possible via comparison with 400 MHz (15)N-(13)C-(13)C correlation spectroscopy (described separately). 相似文献
97.
The title compounds, bearing an alkyl and/or bromine substituent on nitrogen, were synthesized. Unlike 5-bromo-6-methyluracil, 4-bromo-5-methyl-(2H)-1,2,6-thiadiazin-3-(6H)one 1,1-dioxides have the ability to act as a bromonium ion source. 相似文献
98.
The distances and orientations among reactant centers in the active site of coenzyme B12-dependent ethanolamine deaminase from Salmonella typhimurium have been characterized in the Co(II)-product radical pair state by using X-band electron paramagnetic resonance (EPR) and two-pulse electron spin-echo envelope modulation (ESEEM) spectroscopies in the disordered solid state. The unpaired electron spin in the product radical is localized on C2. Our approach is based on the orientation-selection created in the EPR spectrum of the biradical by the axial electron-electron dipolar interaction. Simulation of the EPR line shape yielded a best-fit Co(II)-C2 distance of 9.3 A. ESEEM spectroscopy performed at four magnetic field values addressed the hyperfine coupling of the unpaired electron spin on C2 with 2H in the C5' methyl group of 5'-deoxyadenosine and in the beta-2H position at C1 of the radical. Global ESEEM simulations (over the four magnetic fields) were weighted by the orientation dependence of the EPR line shape. A Nelder-Mead direct search fitting algorithm was used to optimize the simulations. The results lead to a partial model of the active site, in which C5' is located a perpendicular distance of 1.6 A from the Co(II)-C2 axis, at distances of 6.3 and 3.5 A from Co(II) and C2, respectively. The van der Waals contact of the C5'-methyl group and C2 indicates that C5' remains close to the radical species during the rearrangement step. The C2-Hs-C5' angle including the strongly coupled hydrogen, Hs, and the C5'-Hs orientation relative to the C1-C2 axis are consistent with a linear hydrogen atom transfer coordinate and an in-line acceptor p-orbital orientation. The trigonal plane of the C2 atom defines sub-spaces within the active site for C5' radical migration and hydrogen atom transfers (side of the plane facing Co(II)) and amine migration (side of the plane facing away from Co(II)). 相似文献
99.
Michael Charwath Prof. Dr. Kurt Utvary Joseph M. Kanamueller 《Monatshefte für Chemie / Chemical Monthly》1977,108(5):1093-1097
Prolonged heating of (CH3NPF3)2 in a sealed tube at 120°C yields (CH3N)4P3F7 and PF5. Under the experimental conditions these compounds react to (CH3N)4P3F6
+PF6
–. Reaction of (CH3NPF3)2 in the presence of PF5 leads to a marked decrease in the formation of the ionic compound. The influence of the fluoride donating saltsMF (M=Li, Na, K, Cs) is investigated.
Mit 1 Abbildung
Früher: Alkyliminophosphorsäuretrihalogenide, 1. und 2. Mitt. 相似文献
Mit 1 Abbildung
Früher: Alkyliminophosphorsäuretrihalogenide, 1. und 2. Mitt. 相似文献
100.
Hans-Peter Abicht Peter Lehniger Kurt Issleib 《Journal of organometallic chemistry》1983,250(1):609-616
The complexes of type R2)2 (M = Pd, Pt) are readily deprotonated by n-Buli under various conditions yielding μ-C-bis-dilithiated species. The resulting carbanions are attacked by the electrophiles Mel, Me3SiCl and Ph2PCl to form the corresponding disubstituted derivatives. The reaction with AuCl . PPh3 yields heterobimetallic complexes with two different MC σ-bonds. The compounds obtained are analytically and spectroscopically characterized. 相似文献