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941.
942.
Franck S. Schoonbeek Jan H. van Esch Bas Wegewijs Diederik B. A. Rep Matthijs P. de Haas Teun M. Klapwijk Richard M. Kellogg Ben L. Feringa 《Angewandte Chemie (International ed. in English)》1999,38(10):1393-1397
Hydrogen bonds between urea units allow self-organization of π systems in mono- and bithiophenes into fibers as shown schematically. In these fibers there is a surprisingly high mobility of charge carriers as determined by pulse-radiolysis time-resolved microwave conductivity measurements. 相似文献
943.
Several open-source hardware and software technologies (RAMPS, Python, PySerial, OpenCV) were used to control an automated flow chemical synthesis system. The system was used to effect the synthesis of a series of benzamides. An inexpensive Raspberry Pi single board computer provided an electronic interface between the control computer and the RAMPS motor driver boards. 相似文献
944.
A General Approach Towards Triazole‐Linked Adenosine Diphosphate Ribosylated Peptides and Proteins 下载免费PDF全文
Qiang Liu Dr. Hans A. V. Kistemaker Dr. Sagar Bhogaraju Prof. Dr. Ivan Dikic Prof. Dr. Herman S. Overkleeft Prof. Dr. Gijsbert A. van der Marel Prof. Dr. Huib Ovaa Dr. Gerbrand J. van der Heden van Noort Dr. Dmitri V. Filippov 《Angewandte Chemie (International ed. in English)》2018,57(6):1659-1662
Current methods to prepare adenosine diphosphate ribosylated (ADPr) peptides are not generally applicable due to the labile nature of this post‐translational modification and its incompatibility with strong acidic conditions used in standard solid‐phase peptide synthesis. A general strategy is presented to prepare ADPr peptide analogues based on a copper‐catalyzed click reaction between an azide‐modified peptide and an alkyne‐modified ADPr counterpart. The scope of this approach was expanded to proteins by preparing two ubiquitin ADPr analogues carrying the biological relevant α‐glycosidic linkage. Biochemical validation using Legionella effector enzyme SdeA shows that clicked ubiquitin ADPr is well‐tolerated and highlights the potential of this strategy to prepare ADPr proteins. 相似文献
945.
Interfacial Nanoprecipitation toward Stable and Responsive Microbubbles and Their Use as a Resuscitative Fluid 下载免费PDF全文
Dr. Yifeng Peng Dr. Raymond P. Seekell Alexis R. Cole Jemima R. Lamothe Andrew T. Lock Sarah van den Bosch Xiaoqi Tang Prof. Dr. John N. Kheir Prof. Dr. Brian D. Polizzotti 《Angewandte Chemie (International ed. in English)》2018,57(5):1271-1276
A new approach has been developed to prepare stable microbubbles (MBs) by interfacial nanoprecipitation of bioabsorbable polymers at air/liquid interfaces. This facile method offers robust control over the morphology and chemophysical properties of MBs by simple chemical modifications. This approach is amenable to large‐scale manufacturing, and is useful to develop functional MBs for advanced biomedical applications. To demonstrate this, a MB‐based intravenous oxygen carrier was created that undergoes pH‐triggered self‐elimination. Intravenous injection of previous MBs increased the risk of pulmonary vascular obstruction. However, we show, for the first time, that our current design is superior, as they 1) yielded no evidence of acute risks in rodents, and 2) improved the survival in a disease model of asphyxial cardiac arrest (from 0 to 100 %), a condition that affects more than 100 000 in‐hospital patients, and carries a mortality of about 90 %. 相似文献
946.
M. Sc. Lisa K. Mahnke Dr. Aleksandar Kondinski M. Sc. Ulrike Warzok Prof. Dr. Christian Näther Dr. Jan van Leusen Prof. Dr. Christoph A. Schalley Dr. Kirill Yu. Monakhov Prof. Dr. Paul Kögerler Prof. Dr. Wolfgang Bensch 《Angewandte Chemie (International ed. in English)》2018,57(11):2972-2975
A water‐soluble derivative of the polyoxovanadate {V15E6O42} (E=semimetal) archetype enables the study of cluster shell rearrangements driven by supramolecular interactions. A reaction unique to E=Sb, induced exclusively by ligand metathesis in peripheral [Ni(ethylenediamine)3]2+ counterions, results in the formation of the metastable α1* configurational isomer of the {V14Sb8O42} cluster type. Contrary to all other polyoxovanadate shell architectures, this isomer comprises an inward‐oriented vanadyl group and is ca. 50 and 12 kJ mol?1 higher in energy than the previously isolated α and β isomers, respectively. We discuss this unexpected reaction in light of supramolecular Sb?O???V and Sb?O???Sb contacts manifested in {V14Sb8O42}2 dimers detected in the solid state. ESI MS experiments confirm the stability of these dimers also in solution and in the gas phase. DFT calculations indicate that other, as of yet elusive isomers of {V14Sb8}, might be accessible as well. 相似文献
947.
Thissa N. Siriwardena Alice Capecchi Bee‐Ha Gan Dr. Xian Jin Dr. Runze He Dr. Dengwen Wei Lan Ma Dr. Thilo Köhler Prof. Dr. Christian van Delden Dr. Sacha Javor Prof. Dr. Jean‐Louis Reymond 《Angewandte Chemie (International ed. in English)》2018,57(28):8483-8487
We used nearest‐neighbor searches in chemical space to improve the activity of the antimicrobial peptide dendrimer (AMPD) G3KL and identified dendrimer T7 , which has an expanded activity range against Gram‐negative pathogenic bacteria including Klebsiellae pneumoniae, increased serum stability, and promising activity in an in vivo infection model against a multidrug‐resistant strain of Acinetobacter baumannii. Imaging, spectroscopic studies, and a structural model from molecular dynamics simulations suggest that T7 acts through membrane disruption. These experiments provide the first example of using virtual screening in the field of dendrimers and show that dendrimer size does not limit the activity of AMPDs. 相似文献
948.
Enzymatic determination of phenols using peanut peroxidase 总被引:4,自引:0,他引:4
The influence of phenol and its derivatives on the kinetics of oxidation of aryldiamines (indicator-substrates) catalyzed by novel plant peroxidase—cationic peanut peroxidase—was studied. The character of influence of phenols on the kinetics of enzymatic oxidation of benzidine, o-dianisidine, and 3,3′,5,5′-tetramethylbenzidine (TMB) with hydrogen peroxide was found to depend on a correlation between redox properties of phenols and the indicator-substrate of peroxidase. Thus, the catalytic activity of peanut peroxidase is inhibited by phenols with redox potentials higher than that of aryldiamines mentioned above, whereas phenols with potentials below those of aryldiamines, play the role of second substrates of the enzyme. The enzymatic procedures for the determination of numerous phenols on the level of their concentrations 0.05–80 μM were developed using the reactions of benzidine, o-dianisidine, and TMB oxidation. Different analytical signals—the indicator reaction rate and the induction period duration—were used for the determination of phenols, belonging to various groups—the inhibitors and second substrates of the enzyme, respectively. 相似文献
949.
B. J. van der Veken R. S. Sanders J. Xiao J. R. Durig 《Journal of Molecular Structure》2001,560(1-3):57-86
Infrared spectra (4000–50 cm−1) of the vapor, amorphous and crystalline solids and Raman spectra (3600–10 cm−1) of the liquid with qualitative depolarization data as well as the amorphous and crystalline solids of methylaminothiophosphoryl difluoride, CH3N(H)P(=S)F2, and three deuterated species, CD3N(H)P(=S)F2, CH3N(D)P(=S)F2, and CD3N(D)P(=S)F2, have been recorded. The spectra indicate that in the vapor, liquid and amorphous solid a small amount of a second conformer is present, whereas only one conformer remains in the low temperature crystalline phase. The near-infrared spectra of the vapor confirms the existence of two conformers in the gas phase. Asymmetric top contour simulation of the vapor shows that the trans conformer is the predominant vapor phase conformer. From a temperature study of the Raman spectrum of the liquid the enthalpy difference between the trans and near-cis conformers was determined to be 368±15 cm−1 (4.41±0.2 kJ/mol), with the trans conformer being thermodynamically preferred. Ab Initio calculations with structure optimization using the 6-31G(d) and 6-311+G(d,p) basis sets at the restricted Hartree–Fock (RHF) and/or with full electron correlation by the perturbation method to second order (MP2) support the occurrence of near-trans (5° from trans) and near-cis (20° from cis) conformers. From the RHF/6-31G(d) calculation the near-trans conformer is predicted to be the more stable form by 451 cm−1 (5.35 kJ/mol) and from the MP2/6-311+G(d,p) calculation by 387 cm−1 (4.63 kJ/mol). All of the normal modes of the near-trans rotamer have been assigned based on infrared band contours, depolarization values and group frequencies and the assignment is supported by the normal coordinate calculation utilizing harmonic force constants from the MP2/6-31G(d) ab initio calculations. 相似文献
950.
van de Waterbeemd H Smith DA Jones BC 《Journal of computer-aided molecular design》2001,15(3):273-286
Lipophilicity, often expressed as distribution coefficients (log D) in octanol/water, is an important physicochemical parameter influencing processes such as oral absorption, brain uptake and various pharmacokinetic (PK) properties. Increasing log D values increases oral absorption, plasma protein binding and volume of distribution. However, more lipophilic compounds also become more vulnerable to P450 metabolism, leading to higher clearance. Molecular size and hydrogen bonding capacity are two other properties often considered as important for membrane permeation and pharmacokinetics. Interrelationships among these physicochemical properties are discussed. Increasing size (molecular weight) often gives higher potency, but inevitably also leads to either higher lipophilicity, and hence poorer dissolution/solubility, or to more hydrogen bonding capacity, which limits oral absorption. Differences in optimal properties between gastrointestinal absorption and uptake into the brain are addressed. Special attention is given to the desired lipophilicity of CNS drugs. In examples using -blockers, Ca channel antagonists and peptidic renin inhibitors we will demonstrate how potency and pharmacokinetic properties need to be balanced. 相似文献