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101.
Tetraammonium cadmium dihydrogenselenite(IV) diselenate(VI), (NH4)4Cd(HSeIVO3)2(SeVIO4)2, is the third example of a compound containing both hydrogen selenite and selenate anions, and has a new structure type. It contains kröhnkite‐like heteropolyhedral chains in which CdO6 octahedra are linked via bridging HSeO3 groups, having their remaining two trans apices decorated by SeO4 groups. The charge‐balancing NH4 groups are involved in weak hydrogen bonding, whereas the H atom of the HSeO3 group provides a strong hydrogen bond [O⋯O = 2.614 (5) Å]. The average Cd—O bond length is 2.298 Å. All atoms are on general positions except Cd (on ). Relations to the kröhnkite‐type compounds Na2Mg(SO3)·2H2O, Ba2CoCl2(SeO3)2 and Ba2Ca(HPO4)2(H2PO4)2, and to the mineral curetonite are discussed. Unit‐cell data are given for an isotypic MnII analogue. 相似文献
102.
Uwe Kolitsch 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(3):m129-m133
Rubidium chromium(III) dioxalate dihydrate [diaquabis(μ‐oxalato)chromium(III)rubidium(I)], [RbCr(C2O4)2(H2O)2], (I), and dicaesium magnesium dioxalate tetrahydrate [tetraaquabis(μ‐oxalato)magnesium(II)dicaesium(I)], [Cs2Mg(C2O4)2(H2O)4], (II), have layered structures which are new among double‐metal oxalates. In (I), the Rb and Cr atoms lie on sites with imposed 2/m symmetry and the unique water molecule lies on a mirror plane; in (II), the Mg atom lies on a twofold axis. The two non‐equivalent Cr and Mg atoms both show octahedral coordination, with a mean Cr—O distance of 1.966 Å and a mean Mg—O distance of 2.066 Å. Dirubidium copper(II) dioxalate dihydrate [diaquabis(μ‐oxalato)copper(II)dirubidium(I)], [Rb2Cu(C2O4)2(H2O)2], (III), is also layered and is isotypic with the previously described K2‐ and (NH4)2CuII(C2O4)2·2H2O compounds. The two non‐equivalent Cu atoms lie on inversion centres and are both (4+2)‐coordinated. Hydrogen bonds are medium‐strong to weak in the three compounds. The oxalate groups are slightly non‐planar only in the Cs–Mg compound, (II), and are more distinctly non‐planar in the K–Cu compound, (III). 相似文献
103.
Bauer O Guerasimova A Sauer S Thamm S Steinfath M Herwig R Janitz M Lehrach H Radelof U 《Rapid communications in mass spectrometry : RCM》2004,18(16):1821-1829
Peptide nucleic acid (PNA) is a novel class of DNA analogues in which the entire sugar-phosphate backbone is replaced by a pseudopeptide counterpart. Owing to its neutral character and the consequent lack of electrostatic repulsion, PNA exhibits very stable heteroduplex formation with complementary nucleic acid that is essentially ionic strength independent and enables hybridization under minimum salt conditions. This feature as well as its superior ion stability and easy ionization compared to DNA renders PNA very attractive for hybridization-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) applications. We have developed an approach to DNA characterization that takes advantage of multiplexed PNA hybridizations analyzed by MALDI-TOFMS. Our motivation was the further development of oligonucleotide fingerprinting, an efficient technique for cDNA and genomic DNA library characterization. Through positive 'charge-tagging' of PNA the efficiency of detection in MALDI-TOFMS was considerably enhanced permitting an unparalleled degree of multiplexing. Results from the simultaneous hybridization of 21 charge-tagged PNA hexamer oligonucleotides showed that genomic DNA and cDNA clones are successfully characterized on the basis of their hybridization profiles. The degree of multiplexing achieved may render a significant increase in throughput and hence efficiency of oligonucleotide fingerprinting possible. 相似文献
104.
105.
Friedemann Leipold Florian Rudroff Marko D. Mihovilovic Uwe T. Bornscheuer 《Tetrahedron: Asymmetry》2013,24(24):1620-1624
The substrate scope of a steroid monooxygenase (STMO) from Rhodococcus rhodochrous DSM 43269 was investigated for a large range of different ketone substrates. These studies revealed that this enzyme not only oxygenates steroids, but also ketone moieties of a series of other open-chain ketones, such as cyclohexyl methyl ketone, cyclopentyl methyl ketone, and 3-acetylindole. Furthermore, the STMO catalyzed the oxygenation of cyclobutanone derivatives. Comparative biotransformations with recombinant Escherichia coli resting cells harboring the STMO, the cycloalkanone monooxygenase (CAMO) from Cylindrocarpon radicicola or the cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus revealed that the STMO is enantiodivergent compared to the CHMO-type. Moreover, the STMO resulted in a higher enantiomeric excess of the product lactones compared to the known BVMOs of the same enantiopreference, such as cyclopentanone monooxygenases. 相似文献
106.
Jahn S Lohmann W Bomke S Baumann A Karst U 《Analytical and bioanalytical chemistry》2012,402(1):461-471
In the present study, a method for the analysis of reactive metabolites via liquid chromatography (LC) with inductively coupled
plasma–mass spectrometry (MS) was developed. A ferrocenyl-modified glutathione (GSH) reagent, consisting of GSH and succinimidyl-3-ferrocenylpropionate,
was synthesized. Derivatization of the tripeptide was performed at the N-terminus, leaving the nucleophilic thiol group vacant
for the attack of electrophilic compounds. The potential of ferrocenylpropionate (FP)-GSH as a trapping agent for reactive
metabolites was investigated using an electrochemical flow-through cell for metabolism simulation coupled online to a LC system
with electrospray ionization mass spectrometric detection. The pharmaceuticals amodiaquine, an antimalarial agent, and clozapine,
an antipsychotic compound, served as model substances. By proving the successful adduct formation between the reactive metabolite
and ferrocene-labeled GSH, it could be shown that FP-GSH is an effective trapping agent which eases routine reversed-phase
LC analyses. In contrast to GSH, which is usually used for the conjugation of reactive metabolites and where the resulting
adducts often show no or only very little retention, FP-GSH facilitates the detection of the corresponding metabolite adducts
due to higher retention times. 相似文献
107.
108.
Marcus Richter Sebastian Hahn Dr. Evgenia Dmitrieva Dr. Frank Rominger Dr. Alexey Popov Prof. Dr. Uwe H. F. Bunz Prof. Dr. Xinliang Feng Dr. Reinhard Berger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1345-1352
Polycyclic aromatic azomethine ylides (PAMYs) are powerful building blocks in the bottom-up synthesis of internally nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) through 1,3-cycloaddition reactions. In this work, the cycloaddition reaction of PAMYs to asymmetric ortho-quinones is presented, which, in contrast to the addition to symmetric para-quinones, facilitates subsequent condensation reactions and allows the synthesis of three helical N-PAHs with ullazine-quinoxaline ( UQ - 1 – 3 ) backbones. UQ - 1 and UQ - 2 possess two helical centers; however, single-crystal X-ray analysis together with the computational modeling of UQ - 3 elucidate the formation of only the thermodynamically most stable geometry with four helical centers in a (P,P,M,M) configuration. For the series UQ - 1 – 3 , the number of redox steps is directly correlated with the number of ullazine or quinoxaline units incorporated into the targeted molecular backbones. A detailed investigation of the spectroscopic and magnetic properties of the radical cation and anion as well as the dication and dianion species by in situ EPR/UV/Vis-NIR spectroelectrochemistry is provided. The excellent optical and redox properties combined with helical geometries render them possibly applicable as chiral emitter or ambipolar charge transport material in organic electronics. 相似文献
109.
110.
Elisabeth Siebert Marius Horch Yvonne Rippers Johannes Fritsch Stefan Frielingsdorf Oliver Lenz Francisco VelazquezEscobar Friedrich Siebert Lars Paasche Uwe Kuhlmann Friedhelm Lendzian Maria‐Andrea Mroginski Ingo Zebger Peter Hildebrandt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(19):5267-5270