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121.
A highly stereoselective and practical synthetic method for ZK118182, which is chemically and metabolically stable and a biologically potent PGD2-analogue developed by Schering AG, is reported. 相似文献
122.
Naoya Ogata 《Angewandte Chemie (International ed. in English)》1988,27(11):1584-1585
123.
Kuroda N Sugihara S Sugihara Y Wada M Kishikawa N Ohba Y Nakashima K 《Journal of chromatography. A》2005,1066(1-2):119-125
For the first time, fluorescence labeling methods for aryl halides with a fluorescent arylboronic acid was developed on the basis of a Suzuki coupling reaction. 4-(4,5-diphenyl-lH-imidazol-2-yl)phenylboronic acid (DPA) was used as a fluorescence labeling reagent. In order to explore its analytical performance, the reaction conditions were optimized using simple bromobenzene derivatives. The reactivity was then investigated with chloro- and iodobenzene derivatives, and also bromobenzene derivatives with different position of substituents. The order of reactivity with DPA: iodobenzene > bromobenzene more more than chlorobenzene derivatives, and p- > m- > o-substituted bromobenzenes. The detection limits of bromobenzene, 4-bromotoluene, and 4-bromoanisole ranged from 0.2 to 1.4 pmol/injection at a signal-to-noise ratio, (S/N) of 3. The applicability of the method to biological samples was also evaluated using clofibrate as the analyte. The reaction was found not only to proceed well but also to be selective for clofibrate even in the presence of plasma components. The method allowed the sensitive detection of clofibrate in human plasma with the detection limit of 170 pmol/mL (260 fmol/injection) at a S/N = 3. The proposed method is highly selective and sensitive and thus would be useful for labeling of aryl halides that do not have other functional groups that could be labeled by currently available fluorescent labeling reagents. 相似文献
124.
Naoya Morohashi Kohei Ebata Tetsutaro Hattori 《Journal of inclusion phenomena and macrocyclic chemistry》2018,90(3-4):279-285
Upon stirring inclusion crystals of p-tert-butylthiacalix[4]arene (2) in solvents with heating, guest compounds were efficiently desorbed to yield guest-free crystals. More specifically, upon treatment with methanol, the exchange of guest compounds with methanol in the crystals, followed by the desorption of the methanol afforded metastable host crystals 2β, whereas, upon treatment with heptane, the dissolution of the inclusion crystals and simultaneous crystallization of compound 2 afforded stable host crystals 2α. Further, a host crystal of p-tert-butylcalix[4]arene (1) was recovered by the treatment of 2:1 (host/guest) inclusion crystals of compound 1 with supercritical carbon dioxide (scCO2), and through the combination of the guest exchange of 1:1 inclusion crystals of compound 1 with hexane and scCO2 treatment of the resulting 2:1 inclusion crystals 12·hexane. Although the recovered host crystal of compound 1 contained a small amount of CO2, it could be reused for the inclusion of organic compounds. 相似文献
125.
Yuki Matsumoto Naoya Inazumi Tadashi Hanaya Yoshimi Sueishi 《Journal of inclusion phenomena and macrocyclic chemistry》2018,92(1-2):205-210
The inclusion constants of tetraalkylammonium salts (ASs) with cucurbit[7]uril (CB[7]) were determined at high-pressures using methylene blue as a chemical indicator. CB[7] formed 1:1 inclusion complexes with ASs. We found a characteristic dependence of the alkyl chain substituents in ASs on the inclusion equilibrium, which was responsible for the formation of clathrate hydrates of the AS in bulk. Furthermore, we examined the effects of external high pressures on the CB[7] inclusion complexations of ASs having different alkyl chain lengths. Pressure dependence experiments allowed us to calculate the reaction volume (ΔV) upon inclusion; i.e., the volume change (ΔVdesolv) accompanying desolvation around the guest molecules and the volume change (ΔVrepel) caused by the water molecules repelled from the CB[7] cavity. The volumetric study for the inclusion of ASs with CB[7] showed that in the tetraheptylammonium ion, one arm (alkyl chain) was encapsulated in the CB[7] cavity, while in other ASs, two arms were located in the cavity. NMR measurements of the complexes and pressure-dependent studies provided unique information on the structures of the inclusion complexes of ASs with CB[7]. 相似文献
126.
Cover Picture: Catalyst‐Enabled Site‐Divergent Stereoselective Michael Reactions: Overriding Intrinsic Reactivity of Enynyl Carbonyl Acceptors (Angew. Chem. Int. Ed. 17/2018) 下载免费PDF全文
127.
Matsuzaki Y Nogami A Iwaki Y Ohta N Yoshida N Aratani N Osuka A Tanaka K 《The journal of physical chemistry. A》2005,109(4):703-713
The electroabsorption (EA) spectra of directly meso-meso-linked porphyrin arrays (Zn, n = 1-3) have been investigated by means of the sum-over-states (SOS) approach at the INDO/S-SCI level theory. The experimental EA spectra of Zn (n > or = 2) exhibit an unusual second-derivative line shape at the exciton split low-energy B(x) band in contrast to the first-derivative spectrum of Z1, which is readily ascribed to a quadratic Stark shift of the B (Soret) band. Although the second-derivative line shape is usually attributed to a difference in the permanent dipole moment (Deltamu) between the ground and excited states, it should be vanishing for Zn due to their essentially D(2)(d) or D(2)(h) symmetry. As pointed out in our previous studies, the interporphyrinic charge-transfer (CT) excited states are accidentally overlapping with the excitonic B bands and the present calculations reveal that the B(x) state is strongly coupled via a transition dipole moment with two such CT states. These situations give rise to a quadratic Stark effect on the B(x) band that is intermediate between Stark shift (first derivative) and Stark broadening (second derivative), and play a central role in establishing the anomalous second derivative nature of the EA spectrum. Moreover, based on the comparison between the theoretical and experimental spectra, there must be an additional factor that further enhances the second derivative nature of the EA spectrum of porphyrin arrays. Discussions on this issue including the preliminary investigations on the role of solvent (PMMA)-induced asymmetry are also presented. 相似文献
128.
We have demonstrated cascade and one-pot reactions, which constitute inverse electron demand hetero-Diels-Alder reaction and oxidative aromatization, to provide substituted quinolines to form aryl aldimines and allylsilanes. The cascade process involves an auto-tandem catalysis; Tf2NH activates these mechanistically distinct reactions. We have found that a multicomponent process starting from aniline, aldehyde, and allylsilane is also available. 相似文献
129.
Ohyama K Wada M Kishikawa N Ohba Y Nakashima K Kuroda N 《Journal of chromatography. A》2005,1064(2):255-259
The advantage of using a stepwise gradient of buffer concentration in CEC was demonstrated with the mixed-mode stationary phase, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP). Before the application of a stepwise gradient, the effect of buffer concentration on the separations of six peptides and tryptic digests was investigated. Bubble formation caused by Joule heating at currents up to 95 microA was successfully suppressed by using SNAIP column even without pressurization, which contributed to a stepwise gradient of buffer concentration. Utilizing the stepwise gradient improved and shortened the separation of six peptides as compared to the separation under an isocratic elution. 相似文献
130.
Kohei Sanui Tomohiko Asahara Naoya Ogata 《Journal of polymer science. Part A, Polymer chemistry》1968,6(5):1195-1207
Acrylates, such as ethyl acrylate, add with amino alcohol to form N-(hydroxyalkyl) β-alanine ester and room-temperature polycondensation follows, forming polyamide in the presence of a basic catalysts, such as alkali metal alkoxide. The reaction medium has an influence on the course of the polycondensation; that is, N-(hydroxyalkyl) polyamide is formed in methanol solution and polyamide ether in other solvents, such as tetrahydrofuran. These two courses of the room-temperature polycondensation have been studied, and the reaction mechanism is discussed in this paper. 相似文献