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871.
Chlorophenols in water were sorbed onto sodium dodecylsulfate (SDS)-alumina (gamma-form) admicelles. The extent of sorption increased with increasing amount of SDS and decreasing solution pH. Conditions for good recovery were obtained when 100 mg SDS and 1.5 g alumina was used at pH 2. However, the yield decreased with a further increase in the SDS concentration due to the formation of normal SDS micelles. The extent of sorption also increased with increasing hydrophobicity of the chlorophenol, indicating that hydrophobic interactions predominate for the collection of analytes. When a cartridge column filled with admicelles was used, >90% of tetrachlorophenol and pentachlorophenol in 200 ml of water samples were rapidly recovered. The sorbed analytes were eluted with 1 ml acetonitrile. The accuracy and precision of the present method were demonstrated for the HPLC analysis with ultraviolet (290 nm) detection of microg l(-1) levels of tetrachlorophenol and pentachlorophenol in river water samples. 相似文献
872.
Takasu K Shimogama T Saiin C Kim HS Wataya Y Brun R Ihara M 《Chemical & pharmaceutical bulletin》2005,53(6):653-661
Several beta-carbolines including naturally occurring substances and their corresponding cationic derivatives were synthesized and evaluated for antimalarial (antiplasmodial) activity in vitro and in vivo. A tetracyclic carbolinium salt was elucidated for antileishmanial and antitrypanosomal activities in vitro as well as antiplasmodial activity. Quarternary carbolinium cations showed much higher potencies in vitro than electronically neutral beta-carbolines and a good correlation was observed between pi-delocalized lipophilic cationic (DLC) structure and antimalarial efficacy. beta-Carbolinium compounds exhibit medium suppressive activity in vivo against rodent malaria. 相似文献
873.
M. Yamamoto M. Hoshi J. Takada A. Sakaguchi K. N. Apsalikov B. I. Gusev 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(1):19-36
Soil samples collected mainly from the southern areas, including Kainar and Karaul settlements, around the Semipalatinsk Nuclear
Test Site of the former USSR were analyzed for 137Cs and Pu isotopes (238Pu,239Pu and 240Pu) by γ-ray and α-ray spectrometry and ICP-MS. The 137Cs inventories varied widely from 170 to 13,600 Bq/m2. The 239,240Pu inventories, values of which are scare in the literature, also varied in the range of 34-2,050 Bq/m2 (most of date being 100-300 Bq/m2). In the areas around Tailan, Sarzal and Karaul settlements where the radioactive cloud related to the first thermonuclear
explosion passed through, higher inventories of these nuclides were observed and especially their 238Pu/239,240Pu activity ratios (0.0064-0.0076) were markedly lower than those attributed to global fallout (0.03-0.04). The observed ratios
might be used as a fingerprint to identify the Pu source of the first thermonuclear event. Most of the 240Pu/239Pu atomic ratios were lower than those of global fallout (0.18) commonly accepted. The contribution of local fallout 239,240Pu was higher (more than 80-90%) in the areas around the Tailan, Sarzal and Karaul settlements than that (30-ca. 60%) in the
other areas. This high Pu contribution was related to the Pu source from the first thermonuclear event.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
874.
Chen R Tagawa M Hoshi N Ogura T Okamoto H Danjo K 《Chemical & pharmaceutical bulletin》2004,52(9):1066-1070
A solid dispersion of the drug can be made using a polymer carrier to improve solubility. Generally, drugs become amorphized when solid dispersion is formed using a polymer carrier. In such high energy conditions, the solubility of the drug molecule is increased. We previously prepared solid dispersion using a spray-drying technique and reported its solubility and crystallinity. In this study, hydroxypropylmethylcellulose (HPMC) was used as the carrier, and tolubutamide was the model drug, which is water-insoluble. Solubility was evaluated by preparing a solid dispersion using a newly developed 4-fluid nozzle spray dryer. Observation of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray drying were atomized to several microns, and they had also become spherical. Assessment of the crystallinity of the spray-dried particles by powder X-ray diffraction and differential scanning calorimetry demonstrated that the tolbutamide had been amorphized, forming a solid dispersion. The apparent release rate constant K of the drug from the spray-dried particles was 4 to 6 times faster than the original drug in pH 1.2, and it was also 1.5 to 1.9 times faster than the original drug in pH 6.8. The 70% release time (T(70)) of the drug from the spray-dried particles was 20 to 30 times faster than the original drug in pH 1.2 solution as well as 2 to 3 times faster than the original drug in pH 6.8 solution. Pharmaceutical preparations prepared in this way using the 4-fluid nozzle system spray dryer formed composite particles, resulting in a remarkably improved dissolution rates of the drug. 相似文献
875.
M. Yamamoto M. Hoshi J. Takada A. Sakaguchi K. N. Apsalikov B. I. Gusev 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(3):607-616
Sediment core samples were collected up to a depth of 25–40 cm from three ponds (P. Korosteli, P. Mihairov and P. Alkat) and two lakes (L. Kanoneruka and L. Semanaika) located in widely separated regions outside the former Semipalatinsk Nuclear Test Site (SNTS) in Kazakhstan. The 137Cs, Pu and U concentrations with depth were determined in samples divided at 1 cm intervals from the top of each core. These sediment cores were dated by the excess 210Pb method. The reservoirs with low sedimentation rates of 0.038–0.41 g·cm–2·y–1 permitted, but not in detail, the estimation of the depositional history of close-in fallout of 137Cs and Pu within these regions. The sediments accumulating an anomalously high 238U concentration of 250–400 Bq/kg were also found for two of the five reservoirs, in which their 234U/238U and 235U/238U activity ratios were 1.3–2.0 and around 0.047 (nearly the same as that of natural U), respectively. Such U enrichment at the subsurface with a thin layer of lower-U sediment at the surface is mainly due to infiltration of lake water containing U from the ground water flowing into the lake or pond, followed by reduction of U(VI) to U(IV) at the redox boundary.The authors would like to express their gratitude to research staff of the Kazakh Scientific Research Institute for Radiation Medicine and Ecology for sediment and soil sampling. This work was supported by a Grant in Aid for Scientific Research from the Ministry of Education and Culture of Japan, Monbusuo International Scientific Research Program during the period of 1995–2003, represented by Profs. M. Hoshi and M. Yamamoto. 相似文献
876.
Y. Ohta A. Nakano M. Matsumoto M. Hoshi 《Journal of Radioanalytical and Nuclear Chemistry》1987,114(1):75-82
Samples of hair from 370 subjects were analysed by neutron activation. The samples were taken from residents of nine different countries: Japan, France, Ivory Coast, Brasil, Paraguay, Canary Islands, Papua New Guinea, Italy and New Zealand. The selenium determination was made using the76Se(n,)77mSe reaction.It was found that the average selenium concentration in the hair of Japanese subjects, both those living in Japan and those living in foreign countries was higher (total average: 0.59±0.14 mg/kg) than those of subjects from other countries (total average: 0.42±0.13 mg/kg).Our results from the determination of the selenium concentration in the hair of individuals from different countries show significant differences between different countries, nevertheless, the selenium content in human hair was small amounts. Since this is likely due to differences in diet. This method was able to analyze quickly for many samples. 相似文献
877.
Hagiwara H Kobayashi K Miya S Hoshi T Suzuki T Ando M Okamoto T Kobayashi M Yamamoto I Ohtsubo S Kato M Uda H 《The Journal of organic chemistry》2002,67(17):5969-5976
The phytotoxins solanapyrones D (1) and E (2) have been synthesized from the decalone prepared by the domino Michael reaction of the kinetic enolate of optically pure acetylcyclohexene with methyl crotonate. The decalone was transformed into a solanapyrone core by equilibration into thermodynamically stable trans-decalone (11), dehydroxylation, and dehydration. Condensation of a methyl acetoacetate equivalent followed by cyclization installed a pyrone moiety. Introduction of a formyl or hydroxymethyl unit into the pyrone ring via Pummerer related reactions furnished solanapyrones D (1) and E (2). 相似文献
878.
A new type of palladium-catalyzed CO(2) recycling reaction using allylic carbonates is described. Reaction of trans-4-methoxycarbonyloxy-2-buten-1-ols in the presence of a palladium catalyst produces cyclic carbonates having a vinyl group via a CO(2) elimination-fixation process. A variety of allylic carbonates participate in the reaction giving cyclic carbonates with high efficiencies. Stereoselective construction of trans-cyclic carbonates is achieved by using nonsymmetric substrates. An enantiospecific reaction proceeds to give chiral cyclic carbonate when a chiral methyl-substituted substrate is subjected to the reaction conditions. 相似文献
879.
Ueno T Koshiyama T Ohashi M Kondo K Kono M Suzuki A Yamane T Watanabe Y 《Journal of the American Chemical Society》2005,127(18):6556-6562
New methods for the synthesis of artificial metalloenzymes are important for the construction of novel biocatalysts and biomaterials. Recently, we reported new methodology for the synthesis of artificial metalloenzymes by reconstituting apo-myoglobin with metal complexes (Ohashi, M. et al., Angew Chem., Int. Ed. 2003, 42, 1005-1008). However, it has been difficult to improve their reactivity, since their crystal structures were not available. In this article, we report the crystal structures of M(III)(Schiff base).apo-A71GMbs (M = Cr and Mn). The structures suggest that the position of the metal complex in apo-Mb is regulated by (i) noncovalent interaction between the ligand and surrounding peptides and (ii) the ligation of the metal ion to proximal histidine (His93). In addition, it is proposed that specific interactions of Ile107 with 3- and 3'-substituent groups on the salen ligand control the location of the Schiff base ligand in the active site. On the basis of these results, we have successfully controlled the enantioselectivity in the sulfoxidation of thioanisole by changing the size of substituents at the 3 and 3' positions. This is the first example of an enantioselective enzymatic reaction regulated by the design of metal complex in the protein active site. 相似文献
880.
Cyclic carbonates are valuable compounds that have applications in a variety of chemical fields. Methodologies for the synthesis of cyclic carbonates are well investigated in recent years, and the most successful and popular procedure is the utilization of CO(2). This paper presents recent progress in the synthesis of cyclic carbonates by a CO(2)-fixation process, which involves novel palladium-catalyzed CO(2)-recycling reactions. 相似文献