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171.
Photoinduced electron transfer between triplet erythrosin dianion and highly charged ionic quenchers
Asim Mansha Günter Grampp Stephan Landgraf 《Monatshefte für Chemie / Chemical Monthly》2011,55(25):11-17
Abstract
The lifetime of the lowest triplet state of the dianion erythrosin B depends on its concentration because of self-quenching. The self-quenching rate constants vary with the solution viscosity at room temperature. Dextrose was used to change the viscosity of aqueous solutions in the range 1 ≤ η ≤ 5.31 cP. Photoinduced electron transfer reactions between the triplet state of the erythrosin dianion and the highly charged ionic quenchers K4[Fe(CN)6] and K4[Mo(CN)8] were investigated in aqueous borate buffer solutions at pH 9.2 using flash photolysis. Electron transfer rates vary from 3.0 × 108 to 1.4 × 108 M−1 s−1 depending on viscosity. 相似文献172.
[structure: see text] The combination of an optimized arginine receptor unit with a semirigid linker carrying a strategically placed primary ammonium group leads to the first synthetic RGD receptor. It binds to the free RGD peptide as well as to cyclo(RGDfV) in water with association constants around 1000 M(-1). RGD mimetics such as benzamidine 6 are not recognized, rendering the new host a prototype of a new class of receptors selective for the true RGD sequence in peptides. 相似文献
173.
174.
The polymerisation of styrene in lyotropic liquid-crystalline (LC) phases of dioctadecyldimethylammonium bromide (DODAB)
in water is explored. Amphiphile concentrations between 20 and 50 wt % are employed. The study is set out as a model study
for polymerisation reactions in nonstabilised, nonfunctional bilayer systems. X-ray characterisation was used to assess the
phase behaviour of the lyotropic mesophases before, during and after polymerisation. The DODAB/water system forms the lamellar
phase within the concentration range considered. Addition of styrene to the lamellar phase of DODAB at an equimolar ratio
induces a phase shift to a bicontinuous cubic phase at elevated temperatures near the phase-transition temperature. Upon polymerisation
within this cubic phase, the phase structure is maintained if the system is kept at constant temperature; however, if the
polymer/amphiphile phase is cooled, the lamellar phase, being typical of the DODAB/water system, is restored. It is concluded
that, as a result of phase separation between the polymer and the amphiphile phase, the polymerisation in lyotropic LC phases
does not provide a stable copy of the templating amphiphile phase. This is in analogy to the observations for polymerisations
in other lyotropic phases.
Received: 16 March 2000 Accepted: 1 July 2000 相似文献
175.
Kiessig S Reissmann J Rascher C Küllertz G Fischer A Thunecke F 《Electrophoresis》2001,22(7):1428-1435
A screening procedure for protein-protein interactions in cellular extracts using a green fluorescent protein (GFP) and affinity capillary electrophoresis (ACE) was established. GFP was fused as a fluorescent indicator to the C-terminus of a cyclophilin (rDmCyp20) from Drosophila melanogaster. Cyclophilins (Cyps) belong to the ubiquitously distributed enzyme family of peptidyl-prolyl cis/trans isomerases (PPlases) and are well known as cellular targets of the immunosuppressive drug cyclosporin A (CsA). The PPlase activity of the GFP fused rDmCyp20 as well as the high affinity to CsA remain intact. Using native gel electrophoresis and ACE mobility-shift assays, it was demonstrated that the known moderate affinity of Cyp20 to the capsid protein p24 of HIV-1 was detectable in the case of rDmCyp20 fused to the fluorescent tag. For the p24 / rDmCyp20-GFP binding an ACE method was established which allowed to determine a dissociation constant of Kd = 20+/-1.5 x 10(-6) M. This result was verified by size-exclusion chromatography and is in good agreement with published data for the nonfused protein. Moreover the fusion protein was utilized to screen rDmCyp20-protein interactions by capillary electrophoresis in biological matrices. A putative ligand of rDmCyp20 in crude extracts of embryonic D. melanogaster was discovered by mobility-shift assays using native gel electrophoresis with fluorescence imaging and ACE with laser-induced fluorescence detection. The approach seems applicable to a wide range of proteins and offers new opportunities to screen for moderate protein-protein interactions in biological samples. 相似文献
176.
Franziska Lauer Sabrina Diehn Stephan Seifert Janina Kneipp Volker Sauerland Cesar Barahona Steffen Weidner 《Journal of the American Society for Mass Spectrometry》2018,29(11):2237-2247
Mixtures of pollen grains of three different species (Corylus avellana, Alnus cordata, and Pinus sylvestris) were investigated by matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF imaging MS). The amount of pollen grains was reduced stepwise from >?10 to single pollen grains. For sample pretreatment, we modified a previously applied approach, where any additional extraction steps were omitted. Our results show that characteristic pollen MALDI mass spectra can be obtained from a single pollen grain, which is the prerequisite for a reliable pollen classification in practical applications. MALDI imaging of laterally resolved pollen grains provides additional information by reducing the complexity of the MS spectra of mixtures, where frequently peak discrimination is observed. Combined with multivariate statistical analyses, such as principal component analysis (PCA), our approach offers the chance for a fast and reliable identification of individual pollen grains by mass spectrometry. 相似文献
177.
Stieghorst Christian Hampel Gabriele Karches Barbara Krenckel Patricia Kudějová Petra Plonka Christian Révay Zsolt Riepe Stephan Welter Katharina Wiehl Norbert 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):307-313
Journal of Radioanalytical and Nuclear Chemistry - For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and... 相似文献
178.
Viktoriia Morad Dr. Michael Wörle Dr. Sergii Yakunin Dr. Gabriele Rainò Olga Nazarenko Markus Fischer Dr. Ivan Infante Prof. Dr. Maksym V. Kovalenko 《Angewandte Chemie (International ed. in English)》2018,57(35):11329-11333
The spatial localization of charge carriers to promote the formation of bound excitons and concomitantly enhance radiative recombination has long been a goal for luminescent semiconductors. Zero‐dimensional materials structurally impose carrier localization and result in the formation of localized Frenkel excitons. Now the fully inorganic, perovskite‐derived zero‐dimensional SnII material Cs4SnBr6 is presented that exhibits room‐temperature broad‐band photoluminescence centered at 540 nm with a quantum yield (QY) of 15±5 %. A series of analogous compositions following the general formula Cs4?xAxSn(Br1?yIy)6 (A=Rb, K; x≤1, y≤1) can be prepared. The emission of these materials ranges from 500 nm to 620 nm with the possibility to compositionally tune the Stokes shift and the self‐trapped exciton emission bands. 相似文献
179.
180.
Prof. Dr. Petra Schwille Prof. Dr. Joachim Spatz Prof. Dr. Katharina Landfester Prof. Dr. Eberhard Bodenschatz Prof. Dr. Stephan Herminghaus Prof. Dr. Victor Sourjik Dr. Tobias J. Erb Prof. Dr. Philippe Bastiaens Prof. Dr. Reinhard Lipowsky Prof. Dr. Anthony Hyman Prof. Dr. Peter Dabrock Dr. Jean‐Christophe Baret Dr. Tanja Vidakovic‐Koch Dr. Peter Bieling Dr. Rumiana Dimova Dr. Hannes Mutschler Dr. Tom Robinson Dr. T.‐Y. Dora Tang Dr. Seraphine Wegner Prof. Dr. Kai Sundmacher 《Angewandte Chemie (International ed. in English)》2018,57(41):13382-13392
A large German research consortium mainly within the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program of MaxSynBio relies solely on the bottom‐up approach to synthetic biology. MaxSynBio focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components. The fundamental insights gained from the activities in MaxSynBio could eventually be utilized for establishing a new generation of biotechnological processes, which would be based on synthetic cell constructs that replace the natural cells currently used in conventional biotechnology. 相似文献