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41.
Dr. Sophie A.‐L. Thétiot‐Laurent Dr. Jérôme Boissier Dr. Anne Robert Prof. Dr. Bernard Meunier 《Angewandte Chemie (International ed. in English)》2013,52(31):7936-7956
After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200 000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free‐swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies. 相似文献
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John Bacsa Maurice Okello Pankaj Singh Vasu Nair 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):285-288
The conformation and tautomeric structure of (Z)‐4‐[5‐(2,6‐difluorobenzyl)‐1‐(2‐fluorobenzyl)‐2‐oxo‐1,2‐dihydropyridin‐3‐yl]‐4‐hydroxy‐2‐oxo‐N‐(2‐oxopyrrolidin‐1‐yl)but‐3‐enamide, C27H22F3N3O5, in the solid state has been resolved by single‐crystal X‐ray crystallography. The electron distribution in the molecule was evaluated by refinements with invarioms, aspherical scattering factors by the method of Dittrich et al. [Acta Cryst. (2005), A 61 , 314–320] that are based on the Hansen–Coppens multipole model [Hansen & Coppens (1978). Acta Cryst. A 34 , 909–921]. The β‐diketo portion of the molecule exists in the enol form. The enol –OH hydrogen forms a strong asymmetric hydrogen bond with the carbonyl O atom on the β‐C atom of the chain. Weak intramolecular hydrogen bonds exist between the weakly acidic α‐CH hydrogen of the keto–enol group and the pyridinone carbonyl O atom, and also between the hydrazine N—H group and the carbonyl group in the β‐position from the hydrazine N—H group. The electrostatic properties of the molecule were derived from the molecular charge density. The molecule is in a lengthened conformation and the rings of the two benzyl groups are nearly orthogonal. Results from a high‐field 1H and 13C NMR correlation spectroscopy study confirm that the same tautomer exists in solution as in the solid state. 相似文献
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Chongqing Wang Christopher Lambert Maurice Hauser Adrian Deuschmann Dr. Carsten Zeilinger Prof. Dr. Klemens Rottner Prof. Dr. Theresia E. B. Stradal Prof. Dr. Marc Stadler Dr. Elizabeth J. Skellam Prof. Dr. Russell J. Cox 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13578-13583
Mutasynthesis of pyrichalasin H from Magnaporthe grisea NI980 yielded a series of unprecedented 4′-substituted cytochalasin analogues in titres as high as the wild-type system (≈60 mg L−1). Halogenated, O-alkyl, O-allyl and O-propargyl examples were formed, as well as a 4′-azido analogue. 4′-O-Propargyl and 4′-azido analogues reacted smoothly in Huisgen cycloaddition reactions, whereas p-Br and p-I compounds reacted in Pd-catalysed cross-coupling reactions. A series of examples of biotin-linked, dye-linked and dimeric cytochalasins was rapidly created. In vitro and in vivo bioassays of these compounds showed that the 4′-halogenated and azido derivatives retained their cytotoxicity and antifungal activities; but a unique 4′-amino analogue was inactive. Attachment of larger substituents attenuated the bioactivities. In vivo actin-binding studies with adherent mammalian cells showed that actin remains the likely intracellular target. Dye-linked compounds revealed visualisation of intracellular actin structures even in the absence of phalloidin, thus constituting a potential new class of actin-visualisation tools with filament-barbed end-binding specificity. 相似文献
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Natalie Hell Peter Beiersdorfer Gregory V. Brown Megan E. Eckart Richard L. Kelley Caroline A. Kilbourne Maurice A. Leutenegger Thomas E. Lockard F. Scott Porter Jörn Wilms 《X射线光谱测定》2020,49(1):218-233
X-ray astronomy and ground-based atomic physics have a long history of fruitful collaboration: Sound understanding of the underlying atomic physics is the key to reliable interpretation of the spectra from celestial sources; conversely, astronomical spectra have been used to benchmark and advance atomic physics. This interplay is about to become even more important as we enter a new era of high-resolution X-ray astrophysics with large effective collection area. Although high-resolution observations with the gratings on the Chandra and XMM-Newton observatories continue to drive new science, upcoming planned and proposed missions will open up new discovery space in the near future that is currently challenging to access: high-resolution spectroscopy on extended sources, in the Fe K band, and on short time scales. This review summarizes open questions in these areas and the design parameters for the Hitomi, XRISM, Athena, and Arcus observatories. The expected high quality of spectra taken with these observatories puts new constraints on the accuracy of atomic reference data required to take full advantage of the diagnostic potential of these spectra. 相似文献
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Maurice J. Ahsman Bart C. van der Nagel Ron A. Mathot 《Biomedical chromatography : BMC》2010,24(9):969-976
Currently, pharmacokinetic–pharmacodynamic studies of sedatives and analgesics are performed in neonates and children to find suitable dose regimens. As a result, sensitive assays using only small volumes of blood are necessary to determine drug and metabolite concentrations. We developed an ultra‐performance liquid chromatographic method with tandem mass spectrometry detection for quantification of midazolam, 1‐hydroxymidazolam, hydroxymidazolamglucuronide, morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide in 100 μL of plasma. Cleanup consisted of 96 wells micro‐solid phase extraction, before reversed‐phase chromatographic separation (ultra‐performance liquid chromatography) and selective detection using electrospray ionization tandem mass spectrometry. Separate solid‐phase extraction methods were necessary to quantify morphine, midazolam and their metabolites because of each group's physicochemical properties. Standard curves were linear over a large dynamic range with adequate limits of quantitation. Intra‐ and interrun accuracy and precision were within 85–115% (of nominal concentration using a fresh calibration curve) and 15% (coefficient of variation, CV) respectively. Recoveries were >80% for all analytes, with interbatch CVs (as a measure of matrix effects) of less than 15% over six batches of plasma. Stability in plasma and extracts was sufficient, allowing large autosampler loads. Runtime was 3.00 min per sample for each method. The combination of 96‐well micro‐SPE and UPLC‐MS/MS allows reliable quantification of morphine, midazolam and their major metabolites in 100 μL of plasma. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Advances on the Determination of the Astatine Pourbaix Diagram: Predomination of AtO(OH)2− over At− in Basic Conditions 下载免费PDF全文
Dumitru‐Claudiu Sergentu Dr. David Teze Dr. Andréa Sabatié‐Gogova Dr. Cyrille Alliot Ning Guo Dr. Fadel Bassal Dr. Isidro Da Silva Prof. Dr. David Deniaud Dr. Rémi Maurice Dr. Julie Champion Dr. Nicolas Galland Dr. Gilles Montavon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2964-2971
It is generally assumed that astatide (At?) is the predominant astatine species in basic aqueous media. This assumption is questioned in non‐complexing and non‐reductive aqueous solutions by means of high‐pressure anion‐exchange chromatography. Contrary to what is usually believed, astatide is found to be a minor species at pH=11. A different species, which also bears a single negative charge, becomes predominant when the pH is increased beyond 7. Using competition experiments, an equilibrium constant value of 10?6.9 has been determined for the formation of this species from AtO(OH) with the exchange of one proton. The identification of this species, AtO(OH)2?, is achieved through relativistic quantum mechanical calculations, which rule out the significant formation of the AtO2? species, while leading to a hydrolysis constant of AtO(OH) in excellent agreement with experiment when the AtO(OH)2? species is considered. Beyond the completion of the Pourbaix diagram of astatine, this new information is of interest for the development of 211At radiolabeling protocols. 相似文献