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191.
Swarna A. Gamage Julie A. Spicer Kit Y. Tsang Patrick D. O'Connor Jack U. Flanagan Woo‐Jeong Lee James M. J. Dickson Peter R. Shepherd William A. Denny Gordon W. Rewcastle 《化学:亚洲杂志》2019,14(8):1249-1261
Using a scaffold‐hopping approach, imidazo[1,2‐a]pyridine analogues of the ZSTK474 (benzimidazole) class of phosphatidylinositol 3‐kinase (PI3K) inhibitors have been synthesized for biological evaluation. Compounds were prepared using a heteroaryl Heck reaction procedure, involving the palladium‐catalysed coupling of 2‐(difluoromethyl)imidazo[1,2‐a]pyridines with chloro, iodo or trifluoromethanesulfonyloxy (trifloxy) substituted 1,3,5‐triazines or pyrimidines, with the iodo intermediates being preferred in terms of higher yields and milder reaction conditions. The new compounds maintain the PI3K isoform selectivity of their benzimidazole analogues, but in general show less potency. 相似文献
192.
Lijun Duan Sunny N. Wallace Abigail Engelberth Justin K. Lovelady Edgar C. Clausen Jerry W. King Danielle Julie Carrier 《Applied biochemistry and biotechnology》2009,158(2):362-373
In an effort to increase revenues from a given feedstock, valuable co-products could be extracted prior to biochemical or
thermochemical conversion with subcritical water. Although subcritical water shows significant promise in replacing organic
solvents as an extraction solvent, compound degradation has been observed at elevated extraction temperatures. First order
thermal degradation kinetics from a model system, silymarin extracted from Silybum marianum, in water at pH 5.1 and 100, 120, 140, and 160 °C were investigated. Water pressure was maintained slightly above its vapor
pressure. Silymarin is a mixture of taxifolin, silichristin, silidianin, silibinin, and isosilibinin. The degradation rate
constants ranged from 0.0104 min−1 at 100 °C for silichristin to a maximum of 0.0840 min−1 at 160 °C for silybin B. Half-lives, calculated from the rate constants, ranged from a low of 6.2 min at 160 °C to a high
of 58.3 min at 100 °C, both for silichristin. The respective activation energies for the compounds ranged from 37.2 kJ/gmole
for silidianin to 45.2 kJ/gmole for silichristin. In extracting the silymarin with pure ethanol at 140 °C, no degradation
was observed. However, when extracting with ethanol/water mixtures at and 140 °C, degradation increased exponentially as the
concentration of water increased.
An erratum to this article can be found at 相似文献
193.
Synthesis of (±)-1,2,3-triazolo-3′-deoxy-4′-hydroxymethyl carbanucleosides via ‘click’ cycloaddition
Julie Broggi Nicolas Joubert Sabine Berteina-Raboin Steven P. Nolan 《Tetrahedron》2009,65(6):1162-3347
The synthesis of 1,2,3-triazolo-3′-deoxy-4′-hydroxymethyl carbanucleosides with different reaction conditions and diverse modulations on the heterocycle residues was developed. Heterocycle moieties were efficiently introduced on the pseudo-sugar either via nucleophilic substitution or via 1,3-dipolar Huisgen cycloaddition. With this latter approach, 1,4-disubstituted and 1,4,5-trisubstituted-(±)-[1,2,3]-triazolo-3′-deoxy-4′-hydroxymethyl carbanucleosides were prepared from the corresponding azido-carbocycle and various terminal or internal alkynes. Antiviral activities and cellular toxicities of the final compounds were evaluated as smallpox inhibitors. Unfortunately, at concentrations up to 100 mM, none of them inhibited production of vaccinia virus (Lister strain) or cowpox virus (Brighton strain) in vero cells. 相似文献
194.
Laurent El Kaïm Laurence Grimaud Julie Oble Simon Wagschal 《Tetrahedron letters》2009,50(15):1741-2444
Cyclic imines react with isocyanides and electron-deficient phenols to afford N-aryl piperidines and pyrrolidines in good yields (Ugi-Smiles couplings of cyclic imines). The starting imines were formed by oxidation with N-chlorosuccinimide followed by a base-induced dehydrochlorination. 相似文献
195.
Lihua Bai Jianxia Guo Franklin A. Bontempo III Julie L. Eiseman 《Photochemistry and photobiology》2009,85(4):1011-1019
The ability to noninvasively measure photosensitizer concentration at target tissues will allow optimization of photodynamic therapy (PDT) and could improve outcome. In this study, we evaluated whether preirradiation tumor phthalocyanine 4 (Pc 4) concentrations, measured noninvasively by the optical pharmacokinetic system (OPS), correlated with tumor response to PDT. Mice bearing human breast cancer xenografts were treated with 2 mg kg−1 Pc 4 iv only, laser irradiation (150 J cm−2 ) only, Pc 4 followed by fractionated irradiation or Pc 4 followed by continuous irradiation. Laser irradiation treatment was initiated when the tumor to skin ratio of Pc 4 concentration reached a maximum of 2.1 at 48 h after administration. Pc 4 concentrations in tumor, as well as in Intralipid in vitro , decreased monoexponentially with laser fluence. Pc 4-PDT resulted in significant tumor regression, and tumor response was similar in the groups receiving either fractionated or continuous irradiation treatment after Pc 4. Tumor growth delay following Pc 4-PDT correlated with OPS-measured tumor Pc 4 concentrations at 24 h prior to PDT ( R 2 = 0.86). In excised tumors, OPS-measured Pc 4 concentrations were similar to the HPLC-measured concentrations. Thus, OPS measurements of photosensitizer concentrations can be used to assist in the scheduling of Pc 4-PDT. 相似文献
196.
Greg Hughes Paul O'Shea Julie Goll Danny Gauvreau Jennifer Steele 《Tetrahedron》2009,65(16):3189-5650
Effective protocols for the introduction of chiral α-trifluoromethyl benzyl moieties by nucleophilic displacement of enantiomerically enriched α-trifluoromethyl benzylic triflates are presented. The effects of substrate electronics, solvent polarity, temperature, and base are studied by measuring the diastereomeric or enantiomeric excesses of the displacement products formed by coupling a variety of α-trifluoromethyl benzylic triflates with a range of nucleophiles including amines, carboxylates, thiols, and malonates. Preliminary investigations to elucidate the mechanism(s) involved in the loss of stereochemical integrity at the benzylic center in the nucleophilic displacement reactions are also reported. 相似文献
197.
John K. Meissen Matthew D. Sweeney Matthew Girardi Roger Lawrence Jeffrey D. Esko Julie A. Leary 《Journal of the American Society for Mass Spectrometry》2009,20(4):652-657
The presence of 3-O-sulfated glucosamine residues in heparin or heparan sulfate plays a role in binding to antithrombin III
and HSV infection. In this study, tandem mass spectrometry was used to differentiate between two heparin disaccharide isomers
containing variable sulfate at C6 in a common disaccharide and C3 in a more rare one. The dissociation patterns shown by MS2 and MS3 were clearly distinguishable between the isomers, allowing their differentiation and quantitation. Using this technique,
we show that an octasaccharide with 11 sulfate groups with high affinity for inflammatory chemokine CCL2 does not contain
3-O-sulfated disaccharides. 相似文献
198.
Emmanuelle Lipka Julie Charton Marie‐Pierre Vaccher Marcia Folly‐Klan Jean‐Paul Bonte Claude Vaccher 《Journal of separation science》2009,32(11):1907-1915
Baseline separation of 18 new substituted benzimidazole derivatives, potent AMP‐activated protein kinase (AMPK) activators, with one chiral center, was achieved by CD‐EKC using sulfated and highly sulfated CDs (SCDs and HS‐CDs) as chiral selectors. The influence of the type and concentration of the chiral selectors on the enantioseparations was investigated. The SCDs exhibit a very high enantioselectivity power since they allow excellent enantiomeric resolutions compared to those obtained with the neutral CDs. The enantiomers were resolved with analysis times around 6 min using 25 mM phosphate buffer at pH 2.5 containing either β‐S‐CD, HS‐β‐CD, HS‐γ‐CD (3 or 4% w/v) at 25°C, with a voltage of 20 kV. The apparent association constants of the inclusion complexes were calculated. The study of the solute structure‐enantioseparation relationships seems to show the high contribution of the interactions between the solutes phenyl ring and the CDs to the enantiorecognition process. The optimized method was briefly validated (LOD less than 1%) and the purity of enantiomers of compound 3 was determined. The enantiomer migration shows reversal order depending on the kind of CD. 相似文献
199.
Nanoporous 7 mum thin opal films comprising 35 layers of 200 nm diameter SiO2 spheres were assembled on Pt electrodes and modified with chiral selector moieties on the silica surface. Diffusion of chiral redox species through the opals was studied by cyclic voltammetry. The chiral opal films demonstrate high selectivity for transport of one enantiomer over the other. This chiral permselectivity is attributed to the surface-facilitated transport utilizing noncovalent interactions between the chiral permeant molecules and surface-bound chiral selectors. 相似文献
200.
Lloyd JA Spraggins JM Johnston MV Laskin J 《Journal of the American Society for Mass Spectrometry》2006,17(9):1289-1298
Angiotensin II (DRVYIHPF) and two analogs, (DRVYIAPA and DRVAIHPA), were used as model systems to study the ozonolysis of peptides containing tyrosine and histidine residues. The ESI mass
spectrum of angiotensin II following exposure to ozone showed the formation of adducts containing one, three, and four oxygen
atoms. CID and SID spectra of these adducts were consistent with formation of Tyr+O and His+3O as expected from previous work
with amino acids. However, several fragment ions observed in the CID and SID spectra suggested formation of a rather unexpected
adduct, Tyr+3O, and a small amount of the Phe+O adduct. These findings were confirmed by examining two angiotensin analogs.
Exposure of DRVYIAPA to ozone resulted in the addition of either one or three oxygen atoms on Tyr, while DRVAIHPA showed only the addition of three oxygen atoms—all on His. Other noteworthy minor oxidation products were observed from these
analogs including Tyr+34 Da, His+5 Da, His+34 Da, and His+82 Da. The reaction rates of the peptides with ozone were found
to be similar: second-order rate coefficients are 274 ± 3, 379 ± 6, and 439 ± 34 M−1s−1 for DRVYIAPA, DRVAIHPA, and angiotensin II, respectively. The relative rates indicate (1) an isolated His residue has a slightly greater ozone reactivity
than an isolated Tyr residue, and (2) the reaction rates of isolated residues are not additive when both residues are present
in the same molecule. 相似文献