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961.
962.
Cover Picture: Absolute Configuration from Different Multifragmentation Pathways in Light‐Induced Coulomb Explosion Imaging (ChemPhysChem 16/2016)
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Dr. Martin Pitzer Gregor Kastirke Dr. Maksim Kunitski Dr. Till Jahnke Dr. Tobias Bauer Christoph Goihl Florian Trinter Carl Schober Kevin Henrichs Jasper Becht Stefan Zeller Helena Gassert Markus Waitz Andreas Kuhlins Hendrik Sann Felix Sturm Florian Wiegandt Dr. Robert Wallauer Dr. Lothar Ph. H. Schmidt Allan S. Johnson Manuel Mazenauer Benjamin Spenger Sabrina Marquardt Sebastian Marquardt Prof. Dr. Horst Schmidt‐Böcking Prof. Dr. Jürgen Stohner Prof. Dr. Reinhard Dörner Dr. Markus Schöffler Prof. Dr. Robert Berger 《Chemphyschem》2016,17(16):2448-2448
963.
964.
Michael Frotscher Wilhelm Klein Joseph Bauer Chang‐Ming Fang Jean‐Franois Halet Anatoliy Senyshyn Carsten Baehtz Barbara Albert Prof. Dr. 《无机化学与普通化学杂志》2007,633(15):2626-2630
The literature states different compositions (M/B = 1:2 vs. 2:5) and structures for diborides of molybdenum and tungsten. Using X‐ray and neutron powder diffraction as well as energy and wavelength dispersive electron microprobe analysis, the Mo/B and W/B systems were now reinvestigated. Molybdenum diboride crystallizes as a stoichiometric compound Mo2B4 (formerly described as Mo2B5) in space group (No. 166, a, b = 3.01375(2) Å, c = 20.9541(3) Å), and as a non‐stoichiometric compound MoB2?x (formerly described as MoB2) in P6/mmm (No. 191, a, b = 3.043(2) Å, c = 3.067(2) Å), whereas stoichiometric tungsten diboride W2B4 (formerly described as W2B5) is found to crystallize in space group P63/mmc (No. 194, a, b = 2.9864(4) Å, c = 13.896(2) Å). These results seem to be supported by DFT calculations which show the instability of a hypothetic W2B5. 相似文献
965.
The use of internal standards (ISs) improves the quantitative performance of CE. However, ISs chosen for use in CZE often cannot be used for micellar EKC (MEKC). Therefore 22 substances were investigated as potential ISs in MEKC. These substances were selected based upon a literature search. The substances were investigated using a method similar to the standard operating conditions for MEKC as recommended by S. Terabe. Furthermore, the migration time and the corrected migration time (k(S)) were determined for each substance to establish the migration position relative to other peaks in the electropherograms. A combination of eight substances, selected according to the obtained results (t(m) = 4 up to 12 min), was tested for practical benefit and applicability. The peak area precision was in the range of 0.8 and 1.2% (n = 60), and the peaks were well shaped for all the investigated substances. The selected substances covered a wide migration time window and therefore they can be regarded as suitable for future analysis at any required migration position. 相似文献
966.
The qualitative event-specific polymerase chain reaction detection method of genetically modified (GM) RT73 rapeseed was developed based on the cloned 3' end flanking sequence of RT73 rapeseed integration. The specificity of the method for GM RT73 rapeseed was validated using several different GM rapeseed lines, GM maize lines, GM soybean line, non-GM rapeseed, and other non-GM crops. In this study, the developed method was validated through an interlaboratory study by 12 laboratories from 6 countries. The sensitivity of this method was evaluated using several mixed rapeseed meals with different GM RT73 rapeseed contents from 5.0 to 0.01% prepared by our laboratory. The evaluated results showed that all of the rapeseed endogenous reference high mobility group protein gene (HMG I/Y), figwort mosaic virus 35S (FMV 35S) promoter, and RT73 event-specific fragment could be detected from rapeseed samples at 0.1% (w/w) with a confidence level of more than 95%. All results from the 12 laboratories indicated that the developed method could be considered fit for the detection and identification of GM RT73 rapeseed. 相似文献
967.
Yartys VA Denys RV Maehlen JP Frommen C Fichtner M Bulychev BM Emerich H 《Inorganic chemistry》2007,46(4):1051-1055
Aluminum trihydride (alane) is one of the most promising among the prospective solid hydrogen-storage materials, with a high gravimetric and volumetric density of hydrogen. In the present work, the alane, crystallizing in the gamma-AlH3 polymorphic modification, was synthesized and then structurally characterized by means of synchrotron X-ray powder diffraction. This study revealed that gamma-AlH3 crystallizes with an orthorhombic unit cell (space group Pnnm, a = 5.3806(1) A, b = 7.3555(2) A, c = 5.77509(5) A). The crystal structure of gamma-AlH3 contains two types of AlH6 octahedra as the building blocks. The Al-H bond distances in the structure vary in the range of 1.66-1.79 A. A prominent feature of the crystal structure is the formation of the bifurcated double-bridge bonds, Al-2H-Al, in addition to the normal bridge bonds, Al-H-Al. This former feature has not been previously reported for Al-containing hydrides so far. The geometry of the double-bridge bond shows formation of short Al-Al (2.606 A) and Al-H (1.68-1.70 A) bonds compared to the Al-Al distances in Al metal (2.86 A) and Al-H distances for Al atoms involved in the formation of normal bridge bonds (1.769-1.784 A). The crystal structure of gamma-AlH3 contains large cavities between the AlH6 octahedra. As a consequence, the density is 11% less than for alpha-AlH3. 相似文献
968.
Sturm S Seger C Godejohann M Spraul M Stuppner H 《Journal of chromatography. A》2007,1163(1-2):138-144
Identification of putative biomarker molecules within the genus Corydalis (Papaveraceae) was pursued by combining conventional off-line sample enrichment with high-performance liquid chromatography-solid phase extraction-nuclear magnetic resonance (HPLC-SPE-NMR) based structure elucidation. Off-line reversed phase solid phase extraction (SPE) was used to enrich the desired analytes from a methanolic extract (93 mg dry weight) of a miniscule single tuber (233 mg dry weight) of C. solida. An aliquot of the SPE fraction (2.1 mg) was subjected to separation in the HPLC-SPE-NMR hyphenation. Chromatographic peaks bearing the metabolites under investigation were trapped in the SPE device in a single experiment and transferred to a 600 MHz NMR spectrometer equipped with a 30 microl cryofit insert fed into a 3 mm cryoprobe. Recorded homo- and heteronuclear 1D and 2D NMR data allowed the identification of the three analytes under investigation as protopine, allocryptopine, and N-methyl-laudanidinium acetate. The latter is a rare alkaloid, which has been isolated only once before. 相似文献
969.
Schlapak R Armitage D Saucedo-Zeni N Latini G Gruber HJ Mesquida P Samotskaya Y Hohage M Cacialli F Howorka S 《Langmuir : the ACS journal of surfaces and colloids》2007,23(17):8916-8924
Indium tin oxide (ITO) substrates were modified with a layer of poly(amidoamine) (PAMAM) dendrimers to change their surface properties and, in particular, the substrates' work function. The functionalization procedure involved the electrostatic adsorption of positively charged PAMAM dendrimers of generation five onto negatively polarized ITO surfaces. Three different PAMAM dendrimers were used: PAMAM-NH2 and PAMAM-OH with terminal amine and hydroxyl groups, respectively, as well as Q-PAMAM-NH2, which had been prepared from PAMAM-NH2 by quaternization of the dendrimer's terminal and internal amine groups with methyl iodide. The resulting organic films were analyzed by contact angle goniometry, X-ray photoelectron spectroscopy, ellipsometry, and Kelvin probe force microscopy to confirm the presence of a dense layer. A Langmuir isotherm was derived from surface densities of fluorescence-labeled PAMAM-NH2 dendrimers from which we deduced an equilibrium binding constant, K(eq), of (1.3 +/- 0.3) x 10(5) M(-1). Kelvin probe measurements of the contact potential difference revealed a high reduction of the work function from 4.9 eV for bare ITO to 4.3 eV for ITO with a dense film of PAMAM-NH2 of generation five. PAMAM-OH and Q-PAMAM-NH2 resulted in slightly smaller work function changes. This study illustrates that the work function of ITO can be tuned by adlayers composed of PAMAM dendrimers. 相似文献
970.
Magdans U Torrelles X Angermund K Gies H Rius J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(9):4999-5004
For biomineralization processes, the interaction of the surface of calcite crystals with organic molecules is of particular importance. Especially, biologically controlled biomineralization as in exoskeletons of mollusks and echinoderms, e.g., sea urchin with single-crystal-like spines and shells,1-3 requires molecular control of seed formation and growth process. So far, experiments showing the obvious influence of organic molecules on the morphology and habit of calcite crystals have demonstrated the molecular dimension of the interaction.4-7 Details of the kinetics of growth and dissolution of mineral surfaces influenced by additives are available,8,9 but other experimental data about the structure of the organic/inorganic interface on the atomic scale are rare. On the other hand, complicated organic macromolecules which are involved in biomineralization are numerous, with only a small fraction solved in structure and function so far.10-13 Therefore, model systems have to be designed to provide a basic understanding for the interaction process.14 Using grazing incidence X-ray diffraction combined with molecular modeling techniques, we show that glycine molecules order periodically on the calcite (104) face in competition with the solvent water when exposed to an aqueous solution of the most simple amino acid. In contrast to the general concept of the charge-matching fit of organic molecules on mineral surfaces,4,14 glycine is not attached to the calcite surface directly but substitutes for water molecules in the second hydration layer. 相似文献