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91.
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Summary The chromatographic efficiency and stability of a new octadecyl-bonded polymer (ODP) gel, developed for reversed phase liquid
chromatography (RPLC) by substitution of stearate ester groups for the hydroxyl groups of vinyl alcohol copolymer particles,
were investigated and compared with those of conventional gels. The efficiency of the column packed with the ODP gel was practically
unaffected by repeated alternating passages of distilled water and acetonitrile, apparently because the gel volume was affected
similarly by both solvents. Like conventional ODS columns, the ODP column demonstrated a close correlation between log k’
(capacity factor) and carbon atom number in alkyl alcohols in accordance with Martin’s rule and H ∼ 4 dp, thus indicating
a high column efficiency for these alcohols. The capacity factor of the ODP column for pyridine with acidic eluent was smaller
than that of ODS columns, and the pyridine peak was sharp and symmetrical. 相似文献
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Megumi Kubo Takashi Kikukawa Seiji Miyauchi Akiteru Seki Masakatsu Kamiya Tomoyasu Aizawa Keiichi Kawano Naoki Kamo Makoto Demura 《Photochemistry and photobiology》2009,85(2):547-555
Halorhodopsin (HR) acts as a light‐driven chloride pump which transports a chloride ion from the extracellular (EC) to the cytoplasmic space during a photocycle reaction that includes some photointermediates initiated by illumination. To understand the chloride uptake mechanisms, we focused on a basic residue Arg123 of HR from Natronomonas pharaonis (NpHR), which is the only basic residue located in the EC half ion channel. By the measurements of the visible absorption spectra in the dark and the light‐induced inward current through the membrane, it was shown that the chloride binding and transport ability of NpHR completely disappeared by the change of arginine to glutamine. From flashphotolysis analysis, the photocycle of R123Q differed from that of wildtype NpHR completely. The response of the R123H mutant depended on pH. These facts imply that the positive charge at position 123 is essential for chloride binding in the ground state and for the chloride uptake under illumination. On the basis of the molecular structures of HR and the anion‐transportable mutants of bacteriorhodopsin, the effects of the positive charge and the conformational change of the Arg123 side chain as well as the chloride‐pumping mechanism are discussed. 相似文献
96.
Hiroshi Noguchi Tsuyoshi Michinobu Nozomu Fujii Masahiro Funahashi Masatoshi Tokita Junji Watanabe Kiyotaka Shigehara 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5101-5114
Cyanotolane or fluorotolane mesogens were for the first time introduced into the fumarate monomer under basic conditions. All fumarate monomers undergo radical polymerization in benzene in the presence of dimethyl 2,2′‐azobis(isobutyrate) as an initiator at 60 °C, affording the corresponding poly(fumarate)s with a molecular weight (Mn) of ~ 104 and an exceptionally narrow polydispersity. The phase behaviors of the fumarate monomers and the correspoding poly(fumarate)s were comprehensively investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X‐ray diffraction (XRD) analysis. For the fumarate monomers, fluorotolane derivatives were prone to form higher‐order liquid crystal phases such as a smectic phase, while cyanotolane derivatives tended to show a wide mesophase temperature range, depending on the alkyl chain spacer length. Very surprisingly, these features dramatically weakened when they were polymerized. The mesophase temperature ranges became narrow and completely disappeared for the poly(fumarate)s with a shorter alkyl chain spacer. A nematic phase representing lower‐order arrangements became a predominant liquid crystal phase for the poly(fumarate) carrying cyanotolane mesogens. Only the poly(fumarate) carrying fluorotolane mesogens with a longer alkyl chain spacer displayed the characteristic XRD patterns of the smectic B phase. The transient photocurrent measurements of the fumarate monomer with cyanotolane mesogens displayed a hole mobility of the order of 10?4–10?5 cm2 V?1 s?1 at room temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5101–5114, 2008 相似文献
97.
Development of sulfide glass-ceramic electrolytes for all-solid-state lithium rechargeable batteries
Akitoshi Hayashi Keiichi Minami Masahiro Tatsumisago 《Journal of Solid State Electrochemistry》2010,14(10):1761-1767
Development of Li2S–P2S5-based glass-ceramic electrolytes is reviewed. Superionic crystals of Li7P3S11 and Li3.25P0.95S4 were precipitated from the Li2S–P2S5 glasses at the selected compositions. These high temperature or metastable phases enhanced conductivity of glass ceramics
up to over 10−3 S cm−1 at room temperature. The original (or mother) glass electrolytes itself showed somewhat lower conductivity of 10−4 S cm−1 and have important role as a precursor for obtaining the superionic crystals, which were not synthesized by a conventional
solid-state reaction. The substitution of P2O5 for P2S5 at the composition 70Li2S·30P2S5 (mol%) improved both conductivity and electrochemical stability of glass-ceramic electrolytes. The all-solid-state In/LiCoO2 cell using the 70Li2S·27P2S5·3P2O5 (mol%) glass-ceramic electrolyte showed initial capacity of 105 mAh g−1 (gram of LiCoO2) at the current density of 0.13 mA cm−2 and exhibited higher electrochemical performance than that using the 70Li2S·30P2S5 glass-ceramic electrolyte. 相似文献
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99.
Thummaruk Suksrichavalit Keiichi Yoshimatsu Virapong Prachayasittikul Leif Bülow Lei Ye 《Journal of chromatography. A》2010,1217(23):3635-3641
In this paper, we present a new modular approach to immobilize boronic acid ligands that can offer effective separation of glycoproteins. A new “clickable” boronic acid ligand was synthesized by introducing a terminal acetylene group into commercially available 3-aminophenyl boronic acid. The clickable ligand, 3-(prop-2-ynyloxycarbonylamino)phenylboronic acid (2) could be easily coupled to azide-functionalized hydrophilic Sepharose using Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction under mild condition. Compared to other boronic acid affinity gels, the new affinity gel displayed superior effectiveness in separating model glycoproteins (ovalbumin and RNase B) from closely related bovine serum albumin and RNase A in the presence of crude Escherichia coli proteins. Because of the simplicity of the immobilization through “click chemistry”, the new ligand 2 is expected to not only offer improved glycoprotein separation in other formats, but also act as a useful building block to develop new chemical sensors for analysis of other glycan compounds. 相似文献
100.