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991.
T P Davis C W Gehrke C W Gehrke T D Cunningham K C Kuo K O Gerhardt H D Johnson C H Williams 《Journal of chromatography. A》1979,162(3):293-310
A remarkably sensitive, simple and selective reversed-phase high-performance liquid chromatographic (HPLC) method has been developed, allowing, for the first time, the direct measurement of histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin and tyramine in a single sample of plasma (2 ml), tissue (0.2 g), or urine. The biogenic amines were modified by pre-column derivatization with o-phthalaldehyde which stabilizes the molecules, aids in extraction, and improves HPLC detection at the nanogram level. To minimize losses during the sampling procedure a careful collection procedure was designed. We developed a simple sample cleanup in which the samples were thawed, neutralized with KOH, immediately derivatized, extracted into ethyl acetate (EtOAc) and then chromatographed by HPLC. The derivatives were stable in EtOAc for more then 24 h. Interfering amino acids were removed from the EtOAc by partitioning twice with Na2HPO4 buffer (pH 10.0). Complete separation was achieved in ca. 60--90 min on a muBondapak phenyl column using a stepwise gradient of acetonitrile and/or methanol-phosphate buffer (pH 5.1). A variable wavelength fluorometer with a 5-microliter flow-cell was used (excitation 340 nm; emission 480 nm). Linearity ranged from 200 pg to 50 ng onto the column. Precision (R.S.D.) for retention times was 1% and for derivatization and injection 2.5%. Recoveries of the seven biogenic amines from plasma spiked with 25 ng/ml averaged 70%, with a relative standard deviation of 6%. Separation studies were also done using a muBondapak C18 column. The effects of various eluents are presented. Gas-liquid chromatography was also investigated but lacked the sensitivity achieved by HPLC. The HPLC method is used routinely for the determination of biogenic amines in plasma from pigs with malignant hyperthemia and thermally stressed bovine. Significant differences in levels of biogenic amines were noted between stressed and non-stressed animals. Data on rat brain tissue samples were compared with the trihydroxyindole method and canine heart tissue was analyzed for ventricular norepinephrine and dopamine. Application of the method to urine from normal persons and a patient with a brain tumor has been demonstrated. 相似文献
992.
David W. Vahey 《Chemical physics》1975,10(2-3):261-270
Equations are presented for the spectral and orientational distribution of unexcited dye molecules in the field of an intense giant laser pulse. The solute dye molecules are linear oscillators that may be broadened either homogeneously or inhomogeneously, and may reorient by sudden jumps over large angles or by small angular steps (brownian rotational motion). The equations are employed to analyze the intensity dependence of fluorescence polarization observed by Mourou and Denariez-Roberge for the system cryptocyanine-glycerin. Their data are consistent with an excited-state deactivation time T1 = 0.4 ± 1.0 ns and a rotational diffusion constant D = 20/T1 = 5.0 × 109 s−1 相似文献
993.
W.C. Herndon 《Tetrahedron》1973,29(1):3-12
Simple MO techniques are described that can be used to count resonance structures for unsaturated hydrocarbons, ions, and radicals. Alternant or non-alternant unsaturated species can be treated accurately and rapidly. The relationship of the structure count to the calculated values of highest filled and lowest vacant HMO energy levels is discussed. A qualitative relationship of the structure count with reactivity and stability if exemplified with several cases. A known correspondence of resonance theory and perturbational MO theory, previously limited to benzenoid and acyclic systems, is expanded to include all pi molecular systems. 相似文献
994.
H. L. L. M. Van Leengoed N. van der Veen A. A. C. Versteeg R. Ouellet J. E. van Lier W. M. Star 《Photochemistry and photobiology》1993,58(4):575-580
Six sulfonated metallophthalocyanines, chelated with either aluminum or zinc and sulfonated to different degrees, were studied in vivo for their photodynamic activity in a rat skin-fold chamber model. The chamber, located on the back of female WAG/Rij rats, contained a syngeneic mammary carcinoma implanted into a layer of subcutaneous tissue. Twenty-four hours after intravenous administration of 2.5 μmol/kg of one of the dyes, the chambers received a treatment light dose of 600 J/cm2 with monochromatic light of 675 nm at a power density of 100 mW/ cm2. During light delivery and up to a period of 7 days after treatment, vascular effects of tumor and normal tissue were scored. Tumor cell viability was determined by histology and by reimplantation of the chamber contents into the skin of the same animal, either 2 h after treatment or after the 7 day observation period. Vascular effects of both tumor and subcutaneous tissue were strongest with dyes with the lowest degree of sulfonation and decreased with increasing degree of sulfonation. Tumor regrowth did not occur with aluminum phthalocyanine mono- and disulfonate and with zinc phthalocyanine monosulfonate. With the protocol that was used, complete necrosis without recovery was only observed when reimplantation took place at the end of the 7 day follow-up period. Reimplantation 2 h after treatment always resulted in tumor regrowth. At this interval, the presence of viable tumor cells was confirmed histologically. In general tumor tissue vasculature was more susceptible to photodynamic damage than vasculature of the normal tissue. The effect on the circulation of both tumor and normal tissue increased with decreasing degree of sulfonation. Based on this study, the photodynamic effects using the six sulfonated metallophthalocyanines on the vasculature can be ranked from high to low as: AlPcS2= ZnPcS1 > AIPcS1 > AIPcS4 > ZnPcS2 > ZnPcS4. 相似文献
995.
Electron impact mass spectra of eight of the title compounds are reported. Abundant fragment ions were produced under electron impact (EI) conditions and, with one exception, the ($?hbox?ArC??equiv$ O) ions were the base peaks. The EI fragmentation mechanisms of two representative compounds were studied with the aid of high-resolution and mass-analyzed ion kinetic energy spectrometry (MIKES) data. The M(+) ions fragment to give both an odd-electron ion and an even-electron fragment ion. Two H-atom rearrangements proceeding via four-membered ring intermediates and three losses of CO through i- and alpha-fragmentations were observed under EI. On comparing fragmentations under EI conditions with those under FAB conditions for two of the compounds, the fragmentation mechanisms were reasonably similar, with additional fragmentations rationalized in terms of the ionization proton being located on the oxygen atom of the beta-ethoxy group. 相似文献
996.
Zusammenfassung Aus Fichten- und Buchen-Kunstfaserzellstoffen wurden -und -Cellulosen präparativ hergestellt und diese polymeranalog nitriert. Die entstandenen Nitrate wurden durch Behandeln mit Aceton in einen löslichen und unlöslichen Teil getrennt, die gewichtsmäßig bestimmt wurden. Die acetonlöslichen Nitratanteile wurden aus den Acetonlösungen durch steigende Wasserzusätze fraktioniert gefällt und die Fraktionen gewichtsmäßig bestimmt; weiters wurden die reduzierten Viskositäten der Fraktionen bestimmt. Während die Stickstoffgehalte der acetonlöslichen Nitratanteile etwa jenen von Cellulosenitraten entsprechen, betragen die Stickstoffwerte der acetonunlöslichen nur etwa die Hälfte bis ein Drittel davon. In den acetonlöslichen Anteilen liegen im wesentlichen Hexosane vor. Die höchsten Fraktionen der -Cellulosen enthalten Anteile bis annähernd etwa DP 200. Im Gegensatz dazu bestehen die acetonunlöslichen Nitratanteile von - und -Cellulosen hauptsächlich aus Mischungen von Nitraten von Pentosanen und Polyuronsäuren. Die Acetonlöslichkeit von Nitraten laugenlöslicher Anteile aus Kunstfaserzellstoffen gibt demnach orientierende Hinweise auf die chemische Zusammensetzung dieser Anteile.Herrn Prof. Dr.A. Wacek zum 60. Geburtstag gewidmet.Die vorliegenden Untersuchungen wurden bereits in den Jahren 1952 und 1953 durchgeführt. 相似文献
997.
C.C. Lee K.J. Demchuk W.J. Pannekoek R.G. Sutherland 《Journal of organometallic chemistry》1978,162(2):253-269
Ligand exchange reactions between phenanthrene or 9,10-dimethylphenanthrene with ferrocene effected in the presence of AlCl3-Al were carried out under a variety of conditions. With phenanthrene (I), hydrogenation at the C-9 and C-10 positions could take place during the reaction and the cationic products obtained were the η6-phenanthrene-η5-cyclopentadienyliron and η6-9,10-dihydro-phenanthrene-η5-cyclopentadienyliron moncations (II and III), and the η6-phenanthrene---η5-cyclopentadienyliron and η6-9,10-dihydrophenanthrene---η5-cyclopentadienyliron dications (IV and V). With 9,10-dimethylphenanthrene (VI), reactions carried out in refluxing cyclohexane gave the non-hydrogenated η6-9,10-dimethylphenanthrene-η5-cyclopentadienyliron monocation (VII) and η6-9,10-dimethylphenanthrene---η5-cyclopentadienyliron dication (VIII). When higher temperatures were used in an attempt to promote hydrogenation, decomposition predominated and no cationic product could be obtained. These finding are discussed and contrasted with previous results obtained from similar reactions using anthracene or 9,10-dimethylanthracene. 相似文献
998.
Christopher J. Chandler Leslie W. Deady James A. Reiss Vasilios Tzimos 《Journal of heterocyclic chemistry》1982,19(5):1017-1019
The preparation of a series of macrocycles, formed by reaction of HO-(-CH2-CH2-O-)nH with 1,10-phenanthroline-2,9-dicarbonyl chloride (n = 2,3,4) and 1,8-naphthyridine-2,7-dicarbonyl chloride (n = 3,4), is described. An improved synthetic route to 2,7-dimethyl-1,8-naphthyridine 9 is also reported. 相似文献
999.
The compounds CdCr2S4 and CoCr2S4 have been hot pressed into disks that are highly transparent in the infrared. Stoichiometry has been altered by varying the ratio, where M2+ is Cd2+ or Co2+. The effects of nonstoichiometry on optical transmission were determined. Excess M2+ attenuates the transmission much more than excess Cr3+. 相似文献
1000.
R. Arshady G. W. Kenner A. Ledwith 《Journal of polymer science. Part A, Polymer chemistry》1974,12(9):2017-2025
Details are given of the synthesis and purification of p-acetoxystyrene and its solution and suspension copolymerization with styrene. Reactivity ratios, evaluated by the Tidwell-Mortimer method, were r1 (p-acetoxystyrene) = 1.18, and r2 (styrene) = 0.88 for (bulk) solution copolymerization. Corresponding values of the reactivity ratios for suspension copolymerization were, within experimental error, indistinguishable from unity. Thus the copolymer composition is governed simply by the monomer feed composition. Use of a specially designed reactor vessel permits convenient suspension copolymerization of styrene, p-acetoxystyrene, and divinylbenzene to give crosslinked resins having comparatively narrow particle size distributions. Acetoxy groups in the crosslinked resin are cleaved by hydrazine hydrate under very mild conditions to give crosslinked polystyrenes having phenolic groups which, in turn, provide a useful alternative to the more usual chloromethylated polystyrene resins for solid-phase peptide synthesis. 相似文献