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1.
H. Boller 《Monatshefte für Chemie / Chemical Monthly》1973,104(2):545-549
Zusammenfassung Es wird gezeigt, daß die Oktaederlücken des Re3B-Typs in obigen Systemen teilweise durch Sauerstoff aufgefüllt werden. Die Auffüllungsbereichex der Phasen Zr3CoO
x
, Zr3NiO
x
, Hf3CoO
x
und Hf3NiO
x
werden studiert.
Mit 2 Abbildungen 相似文献
On the filled upRe 3 B-type in the systems(Zr, Hf)–(Fe, Co, Ni)–O
It is shown that the octahedral voids of the Re3B-type are partially filled up by oxygen in the above systems. The homogenous ranges ofx of the phases Zr3CoO x , Zr3NiO x , Hf3CoO x , and Hf3NiO x are studied.
Mit 2 Abbildungen 相似文献
2.
H. -E. Baurecht H. Boller H. Nowotny 《Monatshefte für Chemie / Chemical Monthly》1970,101(6):1696-1703
The crystal structure of Cr4As3 has been determined by single crystal photographs: $$\begin{gathered} space group Cm - C_s ^3 \hfill \\ \alpha = 13.16_8 {\AA} \hfill \\ b = 3.54_2 {\AA} \hfill \\ c = 9.30_2 {\AA} \hfill \\ \beta = 102.1_9 \circ \hfill \\ \end{gathered}$$ Cr4As3 crystallizes with a novel structure type, which can be derived from the MnP-structure type. 相似文献
3.
Zusammenfassung Die Phasen V3PC, V3PN, V3AsN, Cr3PC, Cr3PN und Cr3AsC werden hergestellt. Sie sind zu V3AsC isotyp und kristallisieren im aufgefüllten Re3B-Typ. Einige an diesem Strukturtyp beobachtete Regelmäßigkeiten werden diskutiert.
Herrn Prof. Dr.L. Schmid zum 70. Geburtstag gewidmet. 相似文献
The phases V3PC, V3PN, V3AsN, Cr3PC, Cr3PN and Cr3AsC were prepared. They are isotypic with V3AsC and crystallize in the filled up Re3B-type. Some regularities observed with this structure type are discussed.
Herrn Prof. Dr.L. Schmid zum 70. Geburtstag gewidmet. 相似文献
4.
A.G. Khachatryan M.J.H. Luttikhof F.A. van Goor K.-J. Boller 《Applied physics. B, Lasers and optics》2007,86(1):41-47
For the purpose of laser wakefield acceleration, it turns out that the injection of electron bunches longer than the plasma wavelength can also generate accelerated femtosecond bunches with a relatively low energy spread. This is of great interest because such injecting bunches can be provided, e.g., by photo cathode rf linacs. Here we show that when an e-bunch is injected into the wakefield, it is important to take into account the interaction of the injected bunch with the laser pulse in the vacuum region located in front of the plasma. We show that at low energies of the injected bunch, this leads to ponderomotive scattering of the bunch and results in a significant drop of the collection efficiency. For certain injection energies the ponderomotive scattering may result in a smaller energy spread in the accelerated bunch. It is found that the injection position in the laser wakefield plays an important role. Higher collection efficiency can be obtained for certain injection energies, when the bunch is injected in plasma at some distance from the laser pulse; the energy spread, however, is typically larger in this case. We also estimate the minimum trapping energy for the injected electrons and the length of the trapped bunch. PACS 52.38.Kd; 41.75.Jv; 41.85.Ar 相似文献
5.
Frequency-stable operation of a diode-pumped continuous-wave optical parametric oscillator (OPO) of RbTiOAsO(4) is demonstrated. Piezoelectric and fast electro-optic control of the optical length of the two-mirror OPO cavity (resonant for the pump and the idler waves) compensates for thermal changes in the refractive index of the OPO crystal (induced by absorption of pump light) and acoustic perturbations of the cavity length. Pumped by 405mW of the 810-nm output of a GaAlAs masterf-oscillator-tapered-amplifier diode laser system, the OPO generates a power-stable single-frequency signal wave at 1.24microm with an output of 84mW and a spectral bandwidth of less than 10MHz. 相似文献
6.
Boller TM Murphy JM Hapke M Ishiyama T Miyaura N Hartwig JF 《Journal of the American Chemical Society》2005,127(41):14263-14278
This paper describes mechanistic studies on the functionalization of arenes with the diboron reagent B(2)pin(2) (bis-pinacolato diborane(4)) catalyzed by the combination of 4,4'-di-tert-butylbipyridine (dtbpy) and olefin-ligated iridium halide or olefin-ligated iridium alkoxide complexes. This work identifies the catalyst resting state as [Ir(dtbpy)(COE)(Bpin)(3)] (COE = cyclooctene, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaborolanyl). [Ir(dtbpy)(COE)(Bpin)(3)] was prepared by independent synthesis in high yield from [Ir(COD)(OMe)](2), dtbpy, COE, and HBpin. This complex is formed in low yield from [Ir(COD)(OMe)](2), dtbpy, COE, and B(2)pin(2). Kinetic studies show that this complex reacts with arenes after reversible dissociation of COE. An alternative mechanism in which the arene reacts with the Ir(I) complex [Ir(dtbpy)Bpin] after dissociation of COE and reductive elimination of B(2)pin(2) does not occur to a measurable extent. The reaction of [Ir(dtbpy)(COE)(Bpin)(3)] with arenes and the catalytic reaction of B(2)pin(2) with arenes catalyzed by [Ir(COD)(OMe)](2) and dtbpy occur faster with electron-poor arenes than with electron-rich arenes. However, both the stoichiometric and catalytic reactions also occur faster with the electron-rich heteroarenes thiophene and furan than with arenes, perhaps because eta(2)-heteroarene complexes are more stable than the eta(2)-arene complexes and the eta(2)-heteroarene or arene complexes are intermediates that precede oxidative addition. Kinetic studies on the catalytic reaction show that [Ir(dtbpy)(COE)(Bpin)(3)] enters the catalytic cycle by dissociation of COE, and a comparison of the kinetic isotope effects of the catalytic and stoichiometric reactions shows that the reactive intermediate [Ir(dtbpy)(Bpin)(3)] cleaves the arene C-H bond. The barriers for ligand exchange and C-H activation allow an experimental assessment of several conclusions drawn from computational work. Most generally, our results corroborate the conclusion that C-H bond cleavage is turnover-limiting, but the experimental barrier for this bond cleavage is much lower than the calculated barrier. 相似文献
7.
D. D. Arslanov M. Spunei A. K. Y. Ngai S. M. Cristescu I. D. Lindsay S. T. Persijn K. J. Boller F. J. M. Harren 《Applied physics. B, Lasers and optics》2011,103(1):223-228
A fiber-amplified Distributed Bragg Reflector diode laser is used to pump a continuous wave, singly resonant Optical Parametric
Oscillator (OPO). The output radiation covers the 3–4 μm with ability of rapid (100 THz/s) and broad mode-hop-free tuning
(5 cm−1). Wavelength Modulation Spectroscopy is combined with the OPO to take optimal advantage of the spectral scan speed. The sensitivity
of the system was determined as 0.8 ppbv (parts-per-billion by volume) for ethane (C2H6) for the absorption peak at 2996.9 cm−1 recorded in 1.3 seconds, corresponding to a noise equivalent absorption sensitivity (NEAS) of 1.2×10−9 cm−1/Hz1/2. A comparison between results using the 1st, 2nd and 4th harmonic derivative signal from wavelength modulation was performed. The broad continuous tunability was demonstrated by
covering 35 cm−1 while recording absorption features of ethane, methane and water. 相似文献
8.
T. Schröder K. -J. Boller A. Fix R. Wallenstein 《Applied physics. B, Lasers and optics》1994,58(5):425-438
We report on the spectral properties and numerical modelling of a singly resonant Optical Parametric Oscillator (OPO) of Lithium-triBOrate (LBO). The OPO is pumped by the second, third or fourth harmonic of an injection-seeded,Q-switched Nd:YAG laser. The measured OPO parameters are the tuning range, the threshold, the spectral linewidth, the efficiency and the output power. For the LBO-OPO critical type-I phase-matching (xy-plane) provides a wide tuning range and optimum values of the effective nonlinear coefficient. Pumped, for example, by the 355nm third harmonic the spectral range extends from 414 nm to 2.47 µm. With a 15 mm long crystal the OPO generates a total output-pulse energy of 77 mJ with an efficiency of 45%. For 266 nm pump radiation the signal wave is in the near ultraviolet at 307–325 nm. If pumped at 532 nm the OPO generates simultaneously two pairs of signal and idler waves in the infrared (0.707–2.15 µm). The pulse-energy fluctuations of the two pairs are correlated. If, however, the OPO is injection-seeded at one of the signal waves the two wavelength pairs are anti-correlated. The observed wavelength tuning as well as the measured spectral line-widths, threshold energies and efficiencies are in agreement with the values predicted by computer simulation. 相似文献
9.
C–H hydrogen bonds have remarkable impacts on various chemical systems. Here we consider the influence of C–H hydrogen bonds to iodine atoms. Positioning a methyl group between two iodine halogen bond donors of the receptor engendered intramolecular C–H hydrogen bonding (HBing) to the electron-rich belt of both halogen bond donors. When coupled with control molecules, the role of the C–H hydrogen bond was evaluated. Gas-phase density functional theory studies indicated that methyl C–H hydrogen bonds help bias a bidentate binding conformation. Interaction energy analysis suggested that the charged C–H donors augment the halogen bond interaction—producing a >10 kcal mol−1 enhancement over a control lacking the C–H⋯I–C interaction. X-ray crystallographic analysis demonstrated C–H hydrogen bonds and bidentate conformations with triflate and iodide anions, yet the steric bulk of the central functional group seems to impact the expected trends in halogen bond distance. In solution, anion titration data indicated elevated performance from the receptors that utilize C–H Hydrogen Bond enhanced Halogen Bonds (HBeXBs). Collectively, the results suggest that even modest hydrogen bonds between C–H donors and iodine acceptors can influence molecular structure and improve receptor performance.C–H hydrogen bonds to iodine halogen bond donors are shown to improve halogen bonding and molecular preorganization. 相似文献
10.
Commisso R.J. Apruzese J.P. Black D.C. Boller J.R. Moosman B. Mosher D. Stephanakis S.J. Weber B.V. Young F.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(4):1068-1085
The K-shell radiated energy (yield) from neon Z-pinch implosions with annular, gas-puff nozzle radii of 1, 1.75, and 2.5 cm was measured for implosion times from 50 to 300 ns while systematically keeping the implosion kinetic energy nearly constant. The implosions were driven by the Hawk inductive-storage generator at the 0.65-MA level. Initial neutral-neon density distributions from the nozzles were determined with laser interferometry. Measured yields are compared with predictions from zero-dimensional (0-D) scaling models of ideal. One-dimensional (1-D) pinch behavior to both benchmark the scaling models, and to determine their utility for predicting K-shell yields for argon implosions of 200 to >300 ns driven by corresponding currents of 4 to 9 MA, such as envisioned for the DECADE QUAD. For all three nozzles, the 0-D models correctly predict the Z-pinch mass for maximum yield. For the 1and 1.75-cm radius nozzles, the scaling models accurately match the measured yields if the ratio of initial to final radius (compression ratio) is assumed to be 8:1. For the 2.5-cm radius nozzle, the measured yields are only one-third of the predictions. Analysis of K-shell spectral measurements suggest that as much as 70% (50%) of the imploded mass is radiating in the K-shell for the 1-cm (1.75-cm) radius nozzle. That fraction is only 10% for the 2.5-cm radius nozzle. The 0-D scaling models are useful for predicting 1-D-like K-shell radiation yields (better than a factor-of-two accuracy) when a nominal (≈10:1) compression ratio is assumed. However, the compression ratio assumed in the models is only an “effective” quantity, so that further interpretations based on the 0-D analysis require additional justification. The lower-than-predicted yield for the 2.5-cm radius nozzle is associated with larger radius and not with longer implosion time, and is probably a result of two-dimensional effects 相似文献