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111.
Hideaki Hioki Kimihito Matsushita Miwa Kubo Kenichi Harada Mitsuaki Kodama Yoshiyasu Fukuyama 《Tetrahedron》2007,63(46):11315-11324
New methodology for the solid-phase synthesis of benzothiazoles, benzimidazoles, and benzoxazoles has been developed by using a traceless 4-alkoxy-aniline linker. The desired products were released from the polymer support by imine-exchange process coupled with air oxidation. Combinatorial library consisting of 36 members has been synthesized using this linker. The yields are low to good, which highly depend on the building blocks. Recycling of the polymer support was also investigated. 相似文献
112.
Minakawa N Kojima N Hikishima S Sasaki T Kiyosue A Atsumi N Ueno Y Matsuda A 《Journal of the American Chemical Society》2003,125(33):9970-9982
The synthesis and thermal stability of oligodeoxynucleotides (ODNs) containing imidazo[5',4':4,5]pyrido[2,3-d]pyrimidine nucleosides 1-4 (N(N), O(O), N(O), and O(N), respectively) with the aim of developing two sets of new base pairing motifs consisting of four hydrogen bonds (H-bonds) is described. The proposed four tricyclic nucleosides 1-4 were synthesized through the Stille coupling reaction of a 5-iodoimidazole nucleoside with an appropriate 5-stannylpyrimidine derivative, followed by an intramolecular cyclization. These nucleosides were incorporated into ODNs to investigate the H-bonding ability. When one molecule of the tricyclic nucleosides was incorporated into the center of each ODN (ODN I and II, each 17mer), no apparent specificity of base pairing was observed, and all duplexes were less stable than the duplexes containing natural G:C and A:T pairs. On the other hand, when three molecules of the tricyclic nucleosides were consecutively incorporated into the center of each ODN (ODN III and IV, each 17mer), thermal and thermodynamic stabilization of the duplexes due to the specific base pairings was observed. The melting temperature (T(m)) of the duplex containing the N(O):O(N) pairs showed the highest T(m) of 84.0 degrees C, which was 18.2 and 23.5 degrees C higher than that of the duplexes containing G:C and A:T pairs, respectively. This result implies that N(O)and O(N) form base pairs with four H-bonds when they are incorporated into ODNs. The duplex containing N(O):O(N) pairs was markedly stabilized by the assistance of the stacking ability of the imidazopyridopyrimidine bases. Thus, we developed a thermally stable new base pairing motif, which should be useful for the stabilization and regulation of a variety of DNA structures. 相似文献
113.
M Nakagawa K Fukuyama W L Epstein A Hara H Sawada 《Chemical & pharmaceutical bulletin》1989,37(7):1859-1863
Plasminogen activator (PA) and PA inhibitor were partially purified from 2-d-old rat epidermis and characterized in order to elucidate the enzyme-inhibitor interaction in epidermis. PA extracted with buffer containing KSCN was first purified by Blue-Sepharose affinity chromatography. Separation of two PAs, with relative molecular mass (Mr) of 66000 and 44000, was accomplished by Con A-Sepharose column chromatography. The Mr 66000 enzyme had the properties of tissue-type PA (t-PA), while the Mr 44000 enzyme showed those of urokinase-type PA (u-PA) as determined by immunological and fibrin-binding studies. PA inhibitor was extracted in 1,4-piperazinediethanesulphonic acid buffer and purified by (NH4)2SO4 precipitation, gel filtration followed by a Mono Q column in an FPLC system. This inhibitor showed Mr 60000 and inhibited human u-PA activity in a dose- and time-dependent manner, but did not inhibit the activity of t-PA from human and murine melanoma cells or plasmin. It inhibited epidermal PA, Mr 44000, more effectively than it did the Mr 66000 epidermal PA. It was stable at 60 degrees C for 60 min or between pH 5 and 11. This study indicates that both u-PA and t-PA function in normal rat epidermis. On the other hand, an inhibitor which preferentially acts against u-PA exists, but inhibitor to t-PA does not appear to operate under normal epidermal functions. 相似文献
114.
Shigeru Maeda Hideto Fukuyama Emi Yokoyama Takayoshi Kuroiwa Akira Ohki Kensuke Naka 《应用有机金属化学》1997,11(5):393-396
The bioaccumulation and excretion of antimony by the freshwater alga Chlorella vulgaris , which had been isolated from an arsenic-polluted environment, are described. When this alga was cultured in a medium containing 50 μg cm−3 of antimony(III) for 14 days, it was found that Chlorella vulgaris bioaccumulated antimony at concentrations up to 12 000 μg Sb g−1 dry wt after six days' incubation. The antimony concentration in Chlorella vulgaris decreased from 2570 to 1610 μg Sb g−1 dry wt after the cells were transferred to an antimony-free medium. We found that the excreted antimony consists of 40% antimony(V) and 60% antimony(III). This means that the highly toxic antimony(III) was converted to the less toxic antimony (V) by the living organism. Antimony accumulated in living Chlorella vulgaris cells was solvent-fractionated with chloroform/methanol (2:1), and the extract residue was fractionated with 1% sodium dodecyl sulfate (SDS). Gel-filtration chromatography of the solubilized part showed that antimony was combined with proteins whose molecular weight was around 4×104 in the antimony-accumulated living cells. © 1997 by John Wiley & Sons, Ltd. 相似文献
115.
116.
Hiroshi Nagase Akio Watanabe Naoshi Yamamoto Noriko Sato Toshitsugu Kai 《Tetrahedron letters》2007,48(14):2547-2553
Two types of novel skeletons were synthesized from morphinan and 4,5-epoxymorphinan derivatives by using stable and unstable sulfur ylide. 相似文献
117.
K. Fukuyama 《Acta Mathematica Hungarica》2008,118(1-2):155-170
It is proved that two types of discrepancies of the sequence {θ
n
x} obey the law of the iterated logarithm with the same constant. The appearing constants are calculated explicitly for most
of θ > 1.
Dedicated to the memory of Professor Walter Philipp 相似文献
118.
Katusi Fukuyama 《Acta Mathematica Hungarica》2006,110(3):175-191
Summary We prove that the gap seriesΣf(n
k
x) does not behave like an independent random series when f is a function of bounded variation with rational discontinuity. 相似文献
119.
Stereoselective synthesis of the pentacyclic key intermediate 22 for (-)-lemonomycin (1) has been accomplished using the Ugi 4-CC reaction with our novel isocyanide 8, a cross-metathesis of 13 and allylsilane and a subsequent intramolecular Hosomi-Sakurai type reaction. 相似文献
120.
Yamada K Kurokawa T Tokuyama H Fukuyama T 《Journal of the American Chemical Society》2003,125(22):6630-6631
The total synthesis of (+)-duocarmycin A and SA through a common indoline intermediate is described. The key reactions include selective lithiation of a 2,6-dibromoiodobenzene derivative and diastereoselective addition to a chiral nitroalkene, copper-mediated aryl amination, and addition of aryllithium to azlactones. 相似文献