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591.
The equations of ideal Magneto-Hydrodynamics are investigated concerning initial boundary value problems with a perfectly conducting wall condition. The local in time solution is proved to exist uniquely, provided that the normal component of the initial magnetic field vanishes everywhere or nowhere on the boundary. 相似文献
592.
593.
Novel enzymatically recyclable poly(carbonate-urethane) consisting of a diurethane moiety as a hard segment and a carbonate linkage as an enzymatically cleavable unit was prepared by the polycondensation of biodegradable diurethanediol and diethyl carbonate using lipase. The produced poly(carbonate-urethane) was readily transformed by lipase into the corresponding cyclic oligomers which were more easily repolymerized by lipase to produce a higher molecular weight poly(carbonate-urethane) than that of the parent poly(carbonate-urethane). 相似文献
594.
Mibe T Chang WC Nakano T Ahn DS Ahn JK Akimune H Asano Y Daté S Ejiri H Fujimura H Fujiwara M Hicks K Hotta T Imai K Ishikawa T Iwata T Kawai H Kim ZY Kino K Kohri H Kumagai N Makino S Matsuda T Matsumura T Matsuoka N Miwa K Miyabe M Miyachi Y Morita M Muramatsu N Niiyama M Nomachi M Ohashi Y Ooba T Ohkuma H Oshuev DS Rangacharyulu C Sakaguchi A Sasaki T Shagin PM Shiino Y Shimizu H Sugaya Y Sumihama M Titov AI Toi Y Toyokawa H Wakai A Wang CW Wang SC Yonehara K Yorita T Yoshimura M Yosoi M 《Physical review letters》2005,95(18):182001
Photoproduction of a phi meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections at t = -|t|min do not increase smoothly as Egamma increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that phi mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes. 相似文献
595.
596.
Matsumura S Takahashi T Ueno A Mihara H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(19):4829-4837
The availability of the complementary interaction of nucleobases for influencing the formation of peptide architectures was explored. Nucleobases were incorporated as additional recognition elements in coiled-coil peptides by employing nucleobase amino acids (NBAs), which are artificial L-alpha-amino gamma-nucleobase-butyric acids. The effect of the base-pair interaction on intermolecular recognition between peptides was evaluated through a self-replication reaction. The self-replication reactions of the peptides with complementary base pairs such as thymine-adenine or guanine-cytosine at the g-g' heptad positions were accelerated in comparison with those of the peptides with mismatched base pairs or without nucleobases. However, thymine-adenine pairs at the e-e' positions did not enhance the self-replication. In the presence of a denaturant, the enhancement effects of complementary base pairs on the reaction disappeared. Thermal denaturation studies showed that the thymine-adenine pairs contributed to stabilization of the coiled-coil structure and that the pairs at the g-g' positions were more effective than those at the e-e' positions. The peptide-peptide interaction was reinforced by complementary nucleobase interactions appropriately arranged in the peptide structure; these led to acceleration of the self-replication reactions. 相似文献
597.
598.
599.
Spin-lattice relaxation time (T1) of 29Si nuclei in several Ni-silicides (Ni1?xSix:0.25?x?0.67) were studied at low temperature (1.4?T?4.2 K) by spin-echo technique. The relation of T1T = const. and also very short T1 were observed indicating that the silicides studied were metallic with enough densities of state of 3s-electrons at the Fermi energy (EF). Another feature of the results was that T1 decreased with the increment of silicon concentration. This effect was discussed in connection with the soft X-ray spectroscopy (SXS) data on Ni-silicides and Ni—Al compounds. 相似文献
600.
Microwave spectra of the deuterated acetylene dimers, produced in a molecular beam at 1 K from samples of HCCH, DCCH, and DCCD, were observed using a Fourier transform microwave spectrometer. We observed all variations of deuterated acetylene dimers in which a deuterium atom participates in the hydrogen bond; i.e., (DCCD)2, (DCCH)2, DCCD---DCCH, DCCH---DCCD, HCCH---DCCD, and HCCH---DCCH. Deuterated acetylene dimers with the hydrogen atom located in the hydrogen bond could not be detected. Precise molecular constants were determined for each species. Among the dimers identified, (DCCD)2, (DCCH)2, DCCD---DCCH, and DCCH---DCCD showed evidence of an interconversion tunneling motion like the tunneling observed for (HCCH)2. The tunneling potential of (DCCD)2 was analyzed using a one-coordinate model and the potential depth was determined to be V4 = 35.577 cm−1, which is 2.371 cm−1 deeper than that of (HCCH)2 studied by Fraser et al. (J. Chem. Phys. 89, 6028–6045 (1988)). A one-coordinate model was also applied to the other deutered acetylene dimers by adopting a further assumption of a composite potential. 相似文献