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61.
T. Kubo T. Terai A. Suzuki N. Chikumoto 《Physica C: Superconductivity and its Applications》2009,469(15-20):1143-1145
Effects of fast neutron irradiation and post-annealing on magnetic properties of Rb3C60 were studied through the dc magnetization measurement. Rb3C60 powder samples were prepared in an evacuated quartz glass tube, and the temperature and the magnetic field dependences of dc magnetization were measured before and after irradiation and after post-annealing. The neutron fluences were 1.0, 1.8 and 3.3 × 1016 n/cm2, and the post-annealing was made at a temperature of 473 K for 3 h. Magnetic hysteresis of the samples irradiated at the fluence of 1.8 and 3.3 × 1016 n/cm2 disappeared, and the hysteresis curves hardly changed at the fluence of 1.0 × 1016 n/cm2. As for the post-annealing effect, the hysteresis curves of the sample irradiated at the fluence of 1.8 × 1016 n/cm2 were completely recovered after annealing, while those of the other samples, which had a magnetic background before irradiation, were not recovered. In this study, it was found that the loss of superconductivity in Rb3C60 powder is observed when the neutron irradiation fluence exceeds 1.0 × 1016 n/cm2, and the lost superconductivity is completely recovered by the post-annealing at 473 K for 3 h. 相似文献
62.
K Yoshino M Fujiwara A Tanaka S Takahashi Y Nambu A Tomita S Miki T Yamashita Z Wang M Sasaki A Tajima 《Optics letters》2012,37(2):223-225
A high-speed quantum key distribution system was developed with the wavelength-division multiplexing (WDM) technique and dedicated key distillation hardware engines. Two interferometers for encoding and decoding are shared over eight wavelengths to reduce the system's size, cost, and control complexity. The key distillation engines can process a huge amount of data from the WDM channels by using a 1 Mbit block in real time. We demonstrated a three-channel WDM system that simultaneously uses avalanche photodiodes and superconducting single-photon detectors. We achieved 12 h continuous key generation with a secure key rate of 208 kilobits per second through a 45 km field fiber with 14.5 dB loss. 相似文献
63.
Dr. Kenichi Kato Dr. Hidetaka Kasai Dr. Akihiro Hori Prof. Dr. Masaki Takata Prof. Dr. Hiroshi Tanaka Prof. Dr. Susumu Kitagawa Akira Kobayashi Dr. Nobuki Ozawa Prof. Dr. Momoji Kubo Dr. Hidekazu Arikawa Prof. Dr. Tatsuya Takeguchi Dr. Masaaki Sadakiyo Prof. Dr. Miho Yamauchi 《化学:亚洲杂志》2016,11(10):1537-1541
The layered P2‐NaxMO2 (M: transition metal) system has been widely recognized as electronic or mixed conductor. Here, we demonstrate that Co vacancies in P2‐NaxCoO2 created by hydrogen reductive elimination lead to an ionic conductivity of 0.045 S cm?1 at 25 °C. Using in situ synchrotron X‐ray powder diffraction and Raman spectroscopy, the composition of the superionic conduction phase is evaluated to be Na0.61(H3O)0.18Co0.93O2. Electromotive force measurements as well as molecular dynamics simulations indicate that the ion conducting species is proton rather than hydroxide ion. The fact that the Co‐stoichiometric compound Nax(H3O)yCoO2 does not exhibit any significant ionic conductivity proves that Co vacancies are essential for the occurrence of superionic conductivity. 相似文献
64.
Sonomi Arata Dr. Yuna Kim Prof. Norihisa Hoshino Dr. Keishiro Tahara Dr. Kiyonori Takahashi Dr. Tomofumi Kadoya Tomonori Inoue Prof. Takayoshi Nakamura Prof. Tomoyuki Akutagawa Prof. Jun-ichi Yamada Prof. Kazuya Kubo 《欧洲无机化学杂志》2023,26(12):e202300017
Unsymmetrical gold(III)-dithiolene complexes are potential candidates for molecular materials that exhibit thermal structural phase transitions. In this study, unsymmetrical ppy-gold(III) (ppy−=C-deprotonated-2-phenylpyridine(−)) complexes [AuC5] and [AuC6] coordinated by dithiolene ligands containing tetrathiafulvalene (TTF) skeletons with pentylthio (2-{bis(pentylthio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate(2−)) and hexylthio groups (2-{bis(hexylthio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate(2−)) were synthesized. Both complexes exhibited a large absorption band at approximately 508 nm, owing to intramolecular ligand-to-ligand charge transfer. One-dimensional columnar structures with head-to-tail molecular arrangements around the metal ions were constructed in the crystals. The flexible alkylthio groups were intercalated into crystalline spaces between dithiolene ligands in the columns. [AuC5] exhibits a simple phase transition at 198 °C between crystalline and isotropic phases irreversibly. The crystalline phase of [AuC6] observed at 25 °C melted at 148 °C. Another crystalline phase grew above 148 °C with a very slow crystallization rate from the liquid phase and was completely transformed into an isotropic phase at 200 °C. 相似文献
65.
Miwa Kubo 《Tetrahedron letters》2006,47(12):1927-1931
We synthesized a peptidocalix[4]arene library consisting of 1000 members that was suitable for peptide recognition in aqueous media. Some peptidocalix[4]arenes in the library were host molecules for guest peptides. Electrostatic interaction between the host and guest molecules was the most important factor for binding in aqueous media. 相似文献
66.
Fully automated liquid chromatography-mass spectrometry determination of 17beta-estradiol in river water 总被引:1,自引:0,他引:1
Watabe Y Kubo T Nishikawa T Fujita T Kaya K Hosoya K 《Journal of chromatography. A》2006,1120(1-2):252-259
Surface modified molecularly imprinted polymers (SM-MIPs) for 17beta-estradiol (E2), utilizing 6-ketoecradiol as a pseudo template were prepared. MIPs for E2 were synthesized using 4-vinyl pyridine and ethylene dimethacrylate as a functional monomer and cross-linking agent, respectively. MIPs selectively retained E2 and provided excellent chromatographic resolution from interfering compounds inherent in river water sample matrices. Therefore, freshly prepared MIPs were applied to quantitative mass spectrometric (negative electrospray ionization mode) detection of low levels of E2 in river water sample. In order to pre-concentrate the target compound for HPLC analysis, column switching was coupled with a pretreatment column packed with the MIPs. The repeatability of actual determinations of river water sample, in which background E2 was not detected, spiked with 50 ng/L of E2 was 2.2% RSD with a detection limit and qualification limit of 1.8 and 5.4 ng/L, respectively. Surface modification of MIP particlefs packed in the pretreatment column provided selective affinity and on-line concentration of low levels of E2 while simultaneously eliminating sample matrix interference, resulting in a significant increase in sensitivity and reproducibility for liquid chromatography-mass spectrometry analysis of E2 in river water sample. 相似文献
67.
Surface structures on rutile TiO2 (001) have been studied by using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional calculations. Prior investigations have observed many kinds of complicated surface structures; however, detailed atomic structures and the mechanism of the reconstructions are still unknown. We evaluate the energetical stability of the surface structures. The calculational results suggest that a [111] microfaceting model is energetically stable compared with the unreconstructed (1 x 1) model. We propose microfaceting structural models that are in good agreement with atomically resolved STM images. This structural concept can be extended to other rutile TiO2 surfaces in general. 相似文献
68.
Mitamura K Setaka M Shimada K Honma S Namiki M Koh E Mizokami A 《Biomedical chromatography : BMC》2005,19(10):796-801
A promising liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) for analysis of the sulfates of 5alpha-androgen, androsterone and epiandrosterone (A-S and EpiA-S) in human serum was developed. The method was used to assess one of the markers of 5alpha-reductase activity of males including patients with prostate cancer (PC). After deproteinization with acetonitrile, the androgen sulfates and the internal standard, [7,7,16,16-2H4]dehydroepiandrosterone-S, were extracted from human serum using a solid-phase extraction cartridge and washed with hexane. The extract was reconstituted and applied to the LC/ESI-MS system operated in the selected ion monitoring mode. The method was validated over the range 0.02-5 microg/mL (A-S) and 0.005-1.5 microg/mL (EpiA-S) using 10 microL of human serum. The method was a concise procedure without chemical or enzymatic hydrolysis of the conjugates, purification by high-performance liquid chromatography and/or derivatization, and proved to be satisfactory in its reproducibility and accuracy. The levels of these androgen sulfates tended to decrease during aging, and the A-S levels in the sera obtained from both healthy males and patients with PC were correlated with their EpiA-S levels. 相似文献
69.
Magnetic properties of three isostructural compounds BaMP2O7 (M = Co, Ni, and Cu) were investigated by dc and ac magnetization and specific heat measurements. BaCuP2O7 was shown to be an excellent quasi-one-dimensional linear-chain Heisenberg antiferromagnet with an exchange constant (J/kB) of 103.8 K (Hamiltonian H = J Sigma SiS(i+1)) and a temperature for the long-range magnetic order (TN) of 0.81 K giving the ratio kBTN/J = 0.78%. BaCoP2O7 and BaNiP2O7 exhibited long-range antiferromagnetic order at TN = 10.4 and 10.1 K, respectively. BaCoP2O7 and BaNiP2O7 showed a large contribution of the short-range correlation above TN. BaNiP2O7 remained in the antiferromagnetic state up to 90 kOe at 2 K, whereas BaCoP2O7 demonstrated two metamagnetic phase transitions at about 52 and 71 kOe at 2 K if the magnetic field was parallel to the easy direction. BaMP2O7 melted incongruently at 1323 K (M = Co), 1344 K (M = Ni), and 1338 K (M = Cu). 相似文献
70.
Jun Oshitani Shiho Takashina Mikio Yoshida Kuniaki Gotoh 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,350(1-3):136-140
The objective of this study is to estimate the contribution of Na+ as a counterion in the formation of H-AOT&Na-AOT-based W/O microemulsions using aqueous NaOH solution by pyranine absorbance measurements. A mixture of an aqueous NaOH solution containing pyranine/H-AOT&Na-AOT/isooctane was emulsified by changing the mixing ratio of Na-AOT (XNa-AOT = 0–1) and the mole fraction of NaOH (XNaOH = [NaOH]/the AOT− concentration in the water pool = 0–1). The phase behavior of the emulsified mixture was evaluated from the absorbance of pyranine at the isosbestic point and by visual observations. W/O microelumsions are formed at the mid-range of XNa-AOT, whereas the emulsified mixture separates into two phases at lower XNa-AOT and higher XNa-AOT. The two phase boundaries shift toward lower XNa-AOT as with increasing XNaOH. The phase behavior depends on the degree of screening of electrostatic repulsions between the polar headgroups of AOT− by the Na+ counterion. Interestingly, nano-sized W/O microemulsions are formed without phase separation using a highly concentrated NaOH aqueous solution when the Na-AOT mixing ratio is appropriately adjusted. The phase behavior was plotted as XNaOH versus XNa-AOT, and the correlation equations for the two phase boundaries were obtained by fitting the points. The contribution of the Na+ counterion from NaOH to W/O microemulsion formation was estimated by the correlation equations. The absorbance of pyranine and the size of W/O microemulsions, as measured by DLS, were plotted as a function of XNa+=(x[Na+ from NaOH]+[Na+ from Na-AOT])/[AOT−], in which x is the ratio contributed by NaOH. The absorbance and size correlates well with XNa+, indicating that XNa+ is a meaningful parameter for quantitatively estimating phase behavior and size variation. 相似文献