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131.
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133.
Castelli F Sarpietro MG Micieli D Stella B Rocco F Cattel L 《Journal of colloid and interface science》2007,316(1):43-52
Molecular interactions between gemcitabine, alone or conjugated with squalene to form the gem-squalene prodrug, with dimyristoylphosphatidylcholine have been investigated by differential scanning calorimetry and Langmuir film balance techniques to gain information about the interaction of gemcitabine and its prodrug with mammalian cell membranes and to evaluate the potential of liposomes as a delivery system for gemcitabine prodrugs. Phospholipids assembled as multilamellar vesicles or monolayers (at the air water interface) have been used as biomembrane models. Different interactions of gemcitabine, its prodrug, and squalene with the lipid were detected by dispersing the compounds in the MLV and were compared with kinetic experiments carried out to consider the ability of the examined compounds to dissolve in an aqueous medium, to migrate through it, and to be captured by multilamellar vesicles. Their ability to be released from drug-loaded liposomes and be taken up by empty vesicles mimicking biomembranes was also considered. Analysis of the differential scanning calorimetry curves reveals that gemcitabine has very little interaction with multilamellar vesicles whereas the gem-squalene prodrug strongly interacts with multilamellar vesicles. The kinetic experiments suggest that an aqueous medium does not permit the prodrug uptake by the biomembrane models, whereas it is allowed when gem-squalene is gradually released by the liposomes. The molecular area/surface pressure isotherms of the gemcitabine/lipid, gem-squalene/lipid, and pure compound monolayers, in agreement with the calorimetric results, indicate that gem-squalene interacts with the phospholipid monolayer with the squalene moiety in contact with the phospholipid chains and gemcitabine protruding in the aqueous medium. 相似文献
134.
135.
Mukesh Pappoppula Flavio S. P. Cardoso B. Owen Garrett Prof. Aaron Aponick 《Angewandte Chemie (International ed. in English)》2015,54(50):15202-15206
A highly enantioselective copper‐catalyzed alkynylation of quinolinium salts is reported. The reaction employs StackPhos, a newly developed imidazole‐based chiral biaryl P,N ligand, and copper bromide to effect a three‐component reaction between a quinoline, a terminal alkyne, and ethyl chloroformate. Under the reaction conditions, the desired products are delivered in high yields with ee values of up to 98 %. The transformation tolerates a wide range of functional groups with respect to both the alkyne and the quinoline starting materials and the products are easily transformed into useful synthons. Efficient, enantioselective syntheses of the tetrahydroquinoline alkaloids (+)‐galipinine, (+)‐angustureine, and (?)‐cuspareine are reported. 相似文献
136.
Yevheniia Velihina Thomas Scattolin Denys Bondar Stepan Pil'o Nataliya Obernikhina Olesksiy Kachkovskyi Ivan Semenyuta Isabella Caligiuri Flavio Rizzolio Volodymyr Brovarets Yevgen Karpichev Steven P. Nolan 《Helvetica chimica acta》2020,103(12):e2000169
New potential bioactive oxazolopyrimidines have been synthesized using two main approaches: the pyrimidine ring annulation on a functionalized oxazole and the benzoyl bromide trimerization followed by rearrangement and formation of the oxazolo[5,4-d]pyrimidine scaffold. The docking analyzes have shown that 7-piperazine substituted oxazolo[4,5-d]pyrimidines 8a – 8c could be potential VEGFR2 inhibitors with high free energy of ligand–protein complex formation (ΔG: −10.1, −9.6, −9.8 kcal/mol, respectively). In vitro antitumor assays confirmed theoretical predictions that oxazolo[4,5-d]pyrimidines 8a – 8c containing positively charged piperazine moiety should demonstrate significantly higher cytotoxic effects. 4-[5-(4-Chlorophenyl)-2-phenyl[1,3]oxazolo[4,5-d]pyrimidin-7-yl]piperazin-1-ium trifluoroacetate ( 8c ) exhibited a slightly higher antiproliferative effect (IC50=0.21 μm ) than doxorubicin (IC50=0.36 μm ) on MDA-MB-231 cell line and has relatively good results on OVCAR-3 (IC50=1.7 μm ) and HCT-116 (IC50=0.24 μm ) cells. 相似文献
137.
We study the ergodic theory of non-conservative C
1-generic diffeomorphisms. First, we show that homoclinic classes of arbitrary diffeomorphisms exhibit ergodic measures whose
supports coincide with the homoclinic class. Second, we show that generic (for the weak topology) ergodic measures of C
1-generic diffeomorphisms are non-uniformly hyperbolic: they exhibit no zero Lyapunov exponents. Third, we extend a theorem
by Sigmund on hyperbolic basic sets: every isolated transitive set Λ of any C
1-generic diffeomorphism f exhibits many ergodic hyperbolic measures whose supports coincide with the whole set Λ. 相似文献
138.
Calsavara LP Dias da Cunha AR Balbino TA Zanin GM de Moraes FF 《Applied biochemistry and biotechnology》2011,165(7-8):1485-1493
The influence of Toruzyme? cyclomaltodextrin glucanotransferase concentration and the presence of ethanol have been studied for the production of α-, β-, and γ-cyclodextrins (CDs) from 15% (w/v) cornstarch, at 65 °C and pH 6, with the aim of increasing CD yield. The selected concentrations for a single batch reactor were 10% (v/v) ethanol and 0.1% (v/v) enzyme, yielding after 12 h, 37% total CDs, of which 52.2% was α-CD, 38.8% β-CD, and 9.0% γ-CD. The enzyme specific activities per unit mass of protein for producing α-, β-, and γ-CD were 37.25, 19.61, and 8.63 U mg(-1), respectively. Total CD yield per milliliter of enzyme was 55 g. To increase CD yield per enzyme charge and thus reduce costs, the production of CDs was tested with two sequential batches in which a single enzyme charge was used. At the end of the first batch, the enzyme was adsorbed either on 65 °C pretreated starch granules or on raw starch, and a second batch was run with this material. The best result, in this case, was obtained for pretreated starch, increasing total CD produced by 57.4%, with 53.2% α-CD, 36.1% β-CD, and 10.7% γ-CD. CD yield per milliliter of enzyme was then 87 g. 相似文献
139.
Consiglio A Grillo G Licciulli F Ceci LR Liuni S Losito N Volpicella M Gallerani R De Leo F 《Current protein & peptide science》2011,12(5):448-454
PlantPIs is a web querying system for a database collection of plant protease inhibitors data. Protease inhibitors in plants are naturally occurring proteins that inhibit the function of endogenous and exogenous proteases. In this paper the design and development of a web framework providing a clear and very flexible way of querying plant protease inhibitors data is reported. The web resource is based on a relational database, containing data of plants protease inhibitors publicly accessible, and a graphical user interface providing all the necessary browsing tools, including a data exporting function. PlantPIs contains information extracted principally from MEROPS database, filtered, annotated and compared with data stored in other protein and gene public databases, using both automated techniques and domain expert evaluations. The data are organized to allow a flexible and easy way to access stored information. The database is accessible at http://www.plantpis.ba.itb.cnr.it/. 相似文献
140.
André JR Clément MJ Adjadj E Toma F Curmi PA Manivet P 《Journal of computer-aided molecular design》2012,26(4):397-407
The dynamics of microtubules is essential for many microtubule-dependent cellular functions such as the mitosis. It has been
recognized for a long time that GTP hydrolysis in αβ-tubulin polymers plays a critical role in this dynamics. However, the effects of the changes in the nature of the guanosine
nucleotide at the E-site in β-tubulin on microtubule structure and stability are still not well understood. In the present work, we performed all-atom
molecular dynamics simulations of a αβα-tubulin heterotrimer harboring a guanosine nucleotide in three different states at the E-site: GTP, GDP-Pi and GDP. We found
that changes in the nucleotide state is associated with significant conformational variations at the α-tubulin N- and β-tubulin M-loops which impact the interactions between tubulin protofilaments. The results also show that GTP hydrolysis reduces
αβ-tubulin interdimer contacts in favor of intradimer interface. From an atomistic point view, we propose a role for α-tubulin glutamate residue 254 in catalytic magnesium coordination and identified a water molecule in the nucleotide binding
pocket which is most probably required for nucleotide hydrolysis. Finally, the results are discussed with reference to the
role of taxol in microtubule stability and the recent tubulin-sT2R crystal structures. 相似文献