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991.
Kosuke Namba Dr. Yukari Kaihara Hirofumi Yamamoto Dr. Hiroshi Imagawa Dr. Keiji Tanino Prof. Dr. Robert M. Williams Prof. Dr. Mugio Nishizawa Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(27):6560-6563
Catalytic cyclization : The Hg(OTf)2‐catalyzed N‐selective cyclization of amide carbonyl moieties for the construction of a quaternary carbon center was developed. The Hg(OTf)2‐catalyzed cyclization of cyclopentylidene alcohol with acylhydrazide afforded the desired cyclopenta[c]pyridazinone in good yield. The subsequent eight steps gave the functionalized cyclopentane with the correct stereochemistry that corresponds to the E ring of palau′amine (see scheme).
992.
Marco Felici Pablo Contreras‐Carballada Dr. Yolanda Vida Dr. Jan M. M. Smits Roeland J. M. Nolte Prof. Dr. Luisa De Cola Prof. Dr. René M. Williams Dr. Martin C. Feiters Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(47):13124-13134
Novel 2‐(1‐substituted‐1H‐1,2,3‐triazol‐4‐yl)pyridine (pytl) ligands have been prepared by “click chemistry” and used in the preparation of heteroleptic complexes of Ru and Ir with bipyridine (bpy) and phenylpyridine (ppy) ligands, respectively, resulting in [Ru(bpy)2(pytl‐R)]Cl2 and [Ir(ppy)2(pytl‐R)]Cl (R=methyl, adamantane (ada), β‐cyclodextrin (βCD)). The two diastereoisomers of the Ir complex with the appended β‐cyclodextrin, [Ir(ppy)2(pytl‐βCD)]Cl, were separated. The [Ru(bpy)2(pytl‐R)]Cl2 (R=Me, ada or βCD) complexes have lower lifetimes and quantum yields than other polypyridine complexes. In contrast, the cyclometalated Ir complexes display rather long lifetimes and very high emission quantum yields. The emission quantum yield and lifetime (Φ=0.23, τ=1000 ns) of [Ir(ppy)2(pytl‐ada)]Cl are surprisingly enhanced in [Ir(ppy)2(pytl‐βCD)]Cl (Φ=0.54, τ=2800 ns). This behavior is unprecedented for a metal complex and is most likely due to its increased rigidity and protection from water molecules as well as from dioxygen quenching, because of the hydrophobic cavity of the βCD covalently attached to pytl. The emissive excited state is localized on these cyclometalating ligands, as underlined by the shift to the blue (450 nm) upon substitution with two electron‐withdrawing fluorine substituents on the phenyl unit. The significant differences between the quantum yields of the two separate diastereoisomers of [Ir(ppy)2(pytl‐βCD)]Cl (0.49 vs. 0.70) are attributed to different interactions of the chiral cyclodextrin substituent with the Δ and Λ isomers of the metal complex. 相似文献
993.
Lin Dong Dr. Heiko Schill Dr. Rebecca L. Grange Dr. Achim Porzelle Dr. Jenny P. Johns Peter G. Parsons Dr. Victoria A. Gordon Dr. Paul W. Reddell Dr. Craig M. Williams Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(42):11307-11318
EBC‐23, 24, 25, 72, 73, 75 and 76 were isolated from the fruit of Cinnamomum laubatii (family Lauraceae) in the Australian tropical rainforests. EBC‐23 ( 1 ) was synthesized stereoselectively, in nine linear steps in 8 % overall yield, to confirm the reported relative stereochemistry and determine the absolute stereochemistry. Key to the total synthesis was a series of Tietze–Smith linchpin reactions. The novel spiroacetal structural motif, exemplified by EBC‐23 ( 1 ), was found to inhibit the growth of the androgen‐independent prostate tumor cell line DU145 in the mouse model, indicating potential for the treatment of refractory solid tumors in adults. 相似文献
994.
Willi A. Brand Tyler B. Coplen Anita T. Aerts‐Bijma J. K. Böhlke Matthias Gehre Heike Geilmann Manfred Gröning Henk G. Jansen Harro A. J. Meijer Stanley J. Mroczkowski Haiping Qi Karin Soergel Hilary Stuart‐Williams Stephan M. Weise Roland A. Werner 《Rapid communications in mass spectrometry : RCM》2009,23(7):999-1019
Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high‐temperature conversion techniques (HTC) a in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2 b and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded:
The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3‐fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for δ18O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen‐isotope ratios (δ18O) of nitrates, sulfates, or organic material should explicitly state in their reports the δ18O values of two or more internationally distributed nitrates (USGS34, IAEA‐NO‐3, and USGS35), sulfates (IAEA‐SO‐5, IAEA‐SO‐6, and NBS 127), or organic material (IAEA‐601 benzoic acid, IAEA‐602 benzoic acid, and IAEA‐600 caffeine), as appropriate to the material being analyzed, had these reference materials been analyzed with unknowns. This procedure ensures that readers will be able to normalize the δ18O values at a later time should it become necessary. The high‐temperature reduction technique for analyzing δ18O and δ2H is not as widely applicable as the well‐established combustion technique for carbon and nitrogen stable isotope determination. To obtain the most reliable stable isotope data, materials should be treated in an identical fashion; within the same sequence of analyses, samples should be compared with working reference materials that are as similar in nature and in isotopic composition as feasible. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
Reference material | δ18O and estimated combined uncertainty c |
---|---|
IAEA‐602 benzoic acid | +71.28 ± 0.36‰ |
USGS35 sodium nitrate | +56.81 ± 0.31‰ |
IAEA‐NO‐3 potassium nitrate | +25.32 ± 0.29‰ |
IAEA‐601 benzoic acid | +23.14 ± 0.19‰ |
IAEA‐SO‐5 barium sulfate | +12.13 ± 0.33‰ |
NBS 127 barium sulfate | +8.59 ± 0.26‰ |
VSMOW2 water | 0‰ |
IAEA‐600 caffeine | ?3.48 ± 0.53‰ |
IAEA‐SO‐6 barium sulfate | ?11.35 ± 0.31‰ |
USGS34 potassium nitrate | ?27.78 ± 0.37‰ |
SLAP water | ?55.5‰ |
995.
Maize kernel hardness classification by near infrared (NIR) hyperspectral imaging and multivariate data analysis 总被引:1,自引:0,他引:1
The use of near infrared (NIR) hyperspectral imaging and hyperspectral image analysis for distinguishing between hard, intermediate and soft maize kernels from inbred lines was evaluated. NIR hyperspectral images of two sets (12 and 24 kernels) of whole maize kernels were acquired using a Spectral Dimensions MatrixNIR camera with a spectral range of 960-1662 nm and a sisuChema SWIR (short wave infrared) hyperspectral pushbroom imaging system with a spectral range of 1000-2498 nm. Exploratory principal component analysis (PCA) was used on absorbance images to remove background, bad pixels and shading. On the cleaned images, PCA could be used effectively to find histological classes including glassy (hard) and floury (soft) endosperm. PCA illustrated a distinct difference between glassy and floury endosperm along principal component (PC) three on the MatrixNIR and PC two on the sisuChema with two distinguishable clusters. Subsequently partial least squares discriminant analysis (PLS-DA) was applied to build a classification model. The PLS-DA model from the MatrixNIR image (12 kernels) resulted in root mean square error of prediction (RMSEP) value of 0.18. This was repeated on the MatrixNIR image of the 24 kernels which resulted in RMSEP of 0.18. The sisuChema image yielded RMSEP value of 0.29. The reproducible results obtained with the different data sets indicate that the method proposed in this paper has a real potential for future classification uses. 相似文献
996.
997.
Eutimio G. Fernández Rodolfo Valdés Yenisley Medina José A. Montero Alejandro Figueroa Williams Ferro Yarysel Guevara Tatiana Álvarez Andrés Tamayo Regla M. Somoza Leonardo Canaán-Haden Jorge L. López 《Chromatographia》2009,70(7-8):1179-1183
Sepharose CL-4B and Sepharose CL-2B with immobilized CB.Hep-1 monoclonal antibody were compared for studying the matrix efficiency in the immunopurification of the recombinant hepatitis B surface antigen (rHBsAg). The elution capacities of both matrices were similar over eight chromatographic cycles, significant differences were only observed in the first purification cycles. A high percentage of the adsorbed rHBsAg was not eluted from both matrices. The rHBsAg purity was not affected by matrix characteristics (pore size and percentage of agarose) and differences between Sepharose CL-4B and Sepharose CL-2B do not provoke differences in the antibody released from the matrices under defined experimental conditions. 相似文献
998.
Ananda S. Amarasekara Dalkeith Green LaToya D. Williams 《European Polymer Journal》2009,45(2):595-3461
Condensation of renewable resources based monomer 2,5-diformylfuran (DFF) and urea at 110 °C by melting a solid mixture gives a crystalline polymer resin in 90% yield. This resin was characterized by elemental analysis, 1H, 13C and 1H-1H COSY NMR, IR, UV, TGA and DTA. The structural unit of this new material consists of one DFF molecule condensed with two urea molecules at the aldehyde group of DFF. A homologous resin was prepared by using 5,5′-oxydimethylenebis(2-furaldehyde) and urea in 84% yield via a similar procedure and characterized as well. 相似文献
999.
Annunziata Lapolla Roberta Seraglia Laura Molin Katherine Williams Chiara Cosma Rachele Reitano Annalisa Sechi Eugenio Ragazzi Pietro Traldi 《Journal of mass spectrometry : JMS》2009,44(3):419-425
Urine samples from healthy subjects as well as diabetic, nephropathic and diabetic‐nephropathic patients were analyzed by matrix assisted laser desorption/ionization (MALDI) mass spectrometry in order to establish evidence of some possible differences in the peptide profile related to the pathological states. Multivariate analysis suggested the possibility of a distinction among the considered groups of patients. Some differences have been found, in particular, in the relative abundances of three ions at m/z 1912, 1219 and 2049. For these reasons, further investigation was carried out by MALDI/TOF/TOF to determine the sequence of these peptides and, consequently, to individuate their possible origin. By this approach, the peptide at m/z 1912 was found to originate from uromodulin, and its lower expression in the case of nephropathy can be well related to the pathological condition. Ions at m/z 2049 and 1219 originate from the collagen α‐1(I) chain precursor and from the collagen α‐5 (IV) chain precursor, respectively, and, also in this case, their different expressions can be related to the pathologies under investigation. The obtained data seem to indicate that urine is an interesting biological fluid to investigate on the peptide profile and to obtain, consequently, information on the dismetabolism activated by specific pathologies. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
1000.
Ch. V. Subba Reddy Edwin H. Walker Jr. S. A. Wicker Sr. Quinton L. Williams Rajamohan R. Kalluru 《Journal of Solid State Electrochemistry》2009,13(12):1945-1949
We synthesized MoO3 nanorods using poly (vinyl pyrrolidone) (PVP) as a surfactant through the hydrothermal route for making a cathode for a lithium
battery. Scanning electron microscopy images reveal the structures to have dimensions on the order of 1–10 μm in length and
50–200 nm in diameter. Analytical techniques such as X-ray diffractometry, Fourier transformation infrared spectroscopy, thermogravimetric
analysis, and cyclic voltammetry were used to characterize the nanorods. The measured specific charge of MoO3 nanorods prepared through a 15-day hydrothermal reaction was 156 mAhg−1 during the initial discharge process. 相似文献