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961.
962.
Rivkin A Yoshimura F Gabarda AE Cho YS Chou TC Dong H Danishefsky SJ 《Journal of the American Chemical Society》2004,126(35):10913-10922
We provide a full account of the discovery of the (E)-9,10-dehydro derivatives of 12,13-desoxyepothilone B (dEpoB), a new class of antitumor agents with promising in vivo preclinical properties. The compounds, which are to date not available by modification of any of the naturally occurring epothilones, were discovered through total chemical synthesis. We describe how our investigations of ring-closing metathesis reactions in epothilone settings led to the first and second generation syntheses of (E)-9,10-dehydro-12,13-desoxyepothilone congener 6. With further modifications, the synthesis was applied to reach a 26-trifluoro derivative compound (see compound 7). To conduct such studies and in anticipation of future development needs, the total synthesis which led to the initial discovery of compound 7 was simplified significantly. The total synthesis methodology used to reach compound 7 was then applied to reach more readily formulated compounds, bearing hydroxy and amino functionality on the 21-position (see compounds 45, 62, and 63). Following extensive in vitro evaluations of these new congeners, compound 7 was nominated for in vivo evaluations in xenograft models. The data provided herein demonstrate a promising therapeutic efficacy, activity against large tumors, nonrelapseability, and oral activity. These results have identified compound 7 as a particularly promising compound for clinical development. The excellent, totally synthetic, route to 7 makes such a program quite feasible. 相似文献
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967.
Jong-Pyng Chyn Kuan-Jiunn Shieh Jeh-Li Chou Yu Wang Gene-Hsiang Lee Cheu-Pyeng Chen 《中国化学会会志》1991,38(6):549-558
The molecular structures of binuclear copper(II) complexes [Cu2REP(μ-OH)(ClO4)2] (4) and [Cu2REP(μ-Cl)Cl2] (5), in which REP = deprotonated 2,6-bis(1′-(4′-(2″-pyridyl)-2′-thiabutyl))-4-methylphenol, have been characterized by single-crystal X-ray diffraction. The former crystallizes in the triclinic space group Pl? with a = 10.156(3), b = 12.631(3), c = 25.128(10) Å, α = 92.03(3), β = 96.84(3), γ = 108.02(2),° and Z ? 2. Complex 5 crystallizes in the monoclinic space group C2/c with a = 12.166(2), b = 11.825(2), c = 18.240(4) Å, β = 100.97(2)°, and Z =4. All copper ions are pentacoordinated with ligation to a sulfur, a nitrogen, and the bridging phenolato oxygen of the REP ligand, the exogenous bridge, and a counteranion. The coordination geometry of each copper of the binuclear copper sites is square pyramidal in both 4 and 5. Magnetic susceptibility measurements in the temperature range 6–300 K reveal a strong antiferromagnetic spin exchange in 5 (exchange integral 2J = ?460 cm?1). A diamagnetic behavior is observed for 4 according to a similar cryomagnetic investigation. The diamagnetism of 4 is further confirmed by measurements of magnetic susceptibility through Evan's method at room temperature. Complex 4 has no EPR signal. The powder EPR spectrum of 5 shows the typical triplet state characteristics with Δm = ±1 transitions at g = 2.15 and a weaker Δm = 2 transition at half field with g = 4.24. 相似文献
968.
The analytical procedure for analysis of methylmercury in fish was developed. It involves microwave-assisted digestion with alkaline solution (tetramethylammonium hydroxide), addition of Cu2+, aqueous-phase derivatization of methylmercury with sodium tetrapropylborate, and subsequent extraction with n-heptane. The methylmercury derivative was desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by electron impact mass spectrometry. Optimum conditions allowed sample throughout to be controlled by the instrumental analysis time (near 7 min per sample) but not by the sample preparation step. At the power of 15-30, 45, and 60-75 W, sample preparation time is only 3.5, 2.5, and 1.5 min, respectively. The proposed method was finally validated by the analysis of three biological certified reference materials, BCR CRM 464 tuna fish, NRC DORM-2 dogfish muscle, and NRC DOLT-2 dogfish liver. The detection limit of the overall procedure was found to be 40 ng/g of biological tissue for methylmercury. The recovery of methylmercury was 91.2-95.3% for tuna, 89.3-94.7% for marlin, and 91.7-94.8% for shark, respectively. The detected and certified values of methylmercury of three biological certified reference materials were as follows: 5.34 +/- 0.30 microg/g (mean +/- S.D.) and 5.50 +/- 0.17 microg/g for CRM 464 tuna fish, 4.34 +/- 0.24 and 4.47 +/- 0.32 microg/g for NRC DORM-2 dogfish muscle, and 0.652 +/- 0.053 and 0.693 +/- 0.055 microg/g for NRC DOLT-2 dogfish liver, respectively. It indicated that the method was well available to quantify the methylmercury in fish. 相似文献
969.
Asymptotic Functional Form Preservation Method for the Perturbation Theory: Application to Anharmonic Oscillators 下载免费PDF全文
The asymptotic functional form preservation method is developed for the perturbation theory to obtain the energy eigenvalues of anharmonic oscillators. The conventional energy perturbative series expansion for the anharmonic oscillator is strongly divergent even if the anharmonicity is small. Employing a transformation containing an unphysical parameter, we analytically continue this series expansion into a new series expansion applicable to all the range of the perturbation parameter. The unphysical parameter is determined by the principle of minimal sensitivity. This new series expansion is reduced to the conventional energy perturbative series expansion for small anharmonicity, and it preserves the correct asymptotic functional form when the perturbation parameter tends to infinity. Then, we use the full‐range energy series expansion to calculate the energy eigenvalues of the anharmonic oscillator. In addition to excellent energy eigenvalues obtained for the oscillator with small and strong anharmonicity, accurate energy eigenvalues can be obtained using the full‐range energy series expansion when the perturbation parameter tends to infinity. 相似文献
970.
Fast and Effective Turn‐on Paper‐based Phosphorescence Biosensor for Detection of Glucose in Serum 下载免费PDF全文
Yi‐An Chen Fu‐Ju Tsai Yu‐Ting Zeng Jing‐Chang Wang Chia Ping Hong Pin‐Hsuan Huang Hsiang‐Ling Chuang Shih‐Yao Lin Chu‐Ting Chan Yu‐Chien Ko Yi‐Chieh Chou Tien‐Li Lin Gene‐Hsiang Lee Mei‐Lin Ho 《中国化学会会志》2016,63(5):424-431
In this study, a turn‐on paper‐based optical analytical system with a rapid, sensitive and quantitative response for glucose was developed. The luminescence sensing material, crystalline iridium(III)‐Zn(II) coordination polymers, or Ir‐Zne, was grown electrochemically on stainless steel mesh and then deposited on filter paper. This sensing substrate was subsequently built up under glucose oxidase encapsulated in hydrogel and then immobilized on egg membrane with the layer‐by‐layer method. Once the glucose solution was dropped onto the paper, the oxygen content was depleted simultaneously with a concomitant increase in the phosphorescence of Ir‐Zne. The detection limit for glucose was 0.05 mM. The linear dynamic range for the determination of glucose was 0.05–8.0 mM with a correlation coefficient (R2) of 0.9956 (y=68.11 [glucose]?14.72). The response time was about 0.12 s, and the sample volume was less than 5 μL. The effects of mesh size, buffer concentration, pH, enzyme concentration, temperature, and interference, and the stability of the biosensor, have also been studied in detail. Finally, the biosensor was successfully applied to the determination of glucose in human serum. 相似文献