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991.
Yin Gao Abouzar Toubaei Xianqi Kong Gang Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(43):11731-11735
Nitroxyl‐iron(II) (HNO‐FeII) complexes are often unstable in aqueous solution, thus making them very difficult to study. Consequently, many fundamental chemical properties of FeII‐bound HNO have remained unknown. Using a comprehensive multinuclear (1H, 15N, 17O) NMR approach, the acidity of the FeII‐bound HNO in [Fe(CN)5(HNO)]3− was investigated and its pKa value was determined to be greater than 11. Additionally, HNO undergoes rapid hydrogen exchange with water in aqueous solution and this exchange process is catalyzed by both acid and base. The hydrogen exchange dynamics for the FeII‐bound HNO have been characterized and the obtained benchmark values, when combined with the literature data on proteins, reveal that the rate of hydrogen exchange for the FeII‐bound HNO in the interior of globin proteins is reduced by a factor of 106. 相似文献
992.
Keun Man SongJong Min Kim Bong Kyun KangChan Soo Shin Chul Gi KoBo Hyun Kong Hyung Koun ChoDae Ho Yoon Hogyoung Kim Sung Min Hwang 《Applied Surface Science》2012,258(8):3565-3570
Nonpolar a-plane GaN layers grown on r-plane sapphire substrates were examined by using a two-step growth process. The higher initial growth pressure for the nucleation layer resulted in the improved crystalline quality with lower density of both threading dislocations and basal stacking faults. This was attributed to the higher degree of initial roughening and recovery time via a growth mode transition from three-dimensional (3D) to quasi two-dimensional (2D) lateral growth. Using Hall-effect measurements, the overgrown Si doped GaN layers grown with higher initial growth pressure were found to have higher mobility. The scattering mechanism due to the dislocations was dominant especially at low temperature (<200 K) for the lower initial growth pressure, which was insignificant for the higher initial growth pressure. The temperature-dependent Hall-effect measurements for the Mg doped GaN with a higher initial growth pressure yielded the activation energy and the acceptor concentration to be 128 meV and 1.2 × 1019 cm−3, respectively, corresponding to about 3.6% of activation at room temperature. Two-step growth scheme with a higher initial growth pressure is suggested as a potential method to improve the performance of nonpolar a-plane GaN based devices. 相似文献
993.
The dynamical properties of one-dimensional random transverse Ising model (RTIM) with a double-Gaussian disorder is investigated by the recursion method. Based on the first twelve recurrences derived analytically, the spin autocorrelation function (SAF) and associated spectral density at high temperature were obtained numerically. Our results indicate that when the standard deviation σg (or OrB) of the exchange couplings Ji (or the random transverse fields Bi) is small, no long-time tail appears in the SAE The spin system undergoes a crossover from a central-peak behavior to a collectivemode behavior, which is the dynamical characteristics of RTIM with the bimodal disorder. However, when σJ (or σB) is large enough, the system exhibits similar dynamics behaviors to those of the RTIM with the Gaussian disorder, i.e., the system exhibits an enhanced central-peak behavior for large σJ or a disordered behavior for large σB. In this instance, SAFs exhibit a similar long-time tail, i.e., C(t) ~ t ^-2 for large t. Similar properties are obtained when Ji (or Bi) satisfy the double-exponential distribution or the double-uniform distribution. Besides, when both the standard deviations and the mean values of the exchange couplings are small, the effects of the Gaussian random bonds may drive the system undergo two crossovers from a triplet state to a doublet state, and then to a collective-mode state. 相似文献
994.
Linlin Kong Esther Amstad Mingtan Hai Xinyou Ke Dong Chen Chun-Xia Zhao David A. Weitz 《中国化学快报》2017,28(9):1897-1900
We use single emulsions as templates to fabricate monodisperse biocompatible microcapsules with a water core. These microcapsules are fabricated using FDA-approved polymer and non-toxic solvents and are of great use in drugs, cosmetics and foods. 相似文献
995.
996.
在同系物方法测定胶束迁移速度(l/tm c ) 的基础上提出了一种同时求算电渗流速率(l/t0) 的t0 和tm c 的新方法, 该法在选择同系物标记物较为适当时, 可以得到更为准确的结果。同时可以减少由t0 测定而带来的误差。 实验结果表明, 采用甲醇等标记物测定电渗流速率时, 由于其在胶束中的溶解使得实测结果较真值偏大,而由此计算得到的tm c 值偏低。t0 、tm c 皆与缓冲液的种类和浓度有关, 这可能是由于缓冲液组成的变化不仅使得离子强度改变, 也使柱管壁和胶束表面的ξ势发生变化所致。同系物标记物的选择对t0 、tmc 测定精度影响的讨论也为实际分析系统t0 、tmc 的测定和分析分离条件的优化选择提供了必要的理论依据。 相似文献
997.
998.
999.
Ionics - Manganese phosphate (Mn3(PO4)2·3H2O) nanosheets are successfully fabricated via a facile chemical precipitation method. The Mn3(PO4)2·3H2O nanosheets synthesized at... 相似文献
1000.
Kai Yao Yiwang Chen Lie Chen Huanling Kong Weihua Zhou Fan Li Xiaohui He Yen Wei 《Journal of polymer science. Part A, Polymer chemistry》2010,48(2):434-442
Novel liquid‐crystalline alternating conjugated copolymers [ P(P(6)CN‐alt‐Cz) and P(P(6)CN‐alt‐MeP) ] with phenylene and carbazolylene or phenylene with methyl substitution onto the main chain have been synthesized through palladium‐catalyzed Suzuki coupling reactions. The influence of the incorporation of carbazolylene and the substituted phenylene into the main chain on the thermal, mesomorphic, and luminescent properties has been investigated by Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, polarized optical microscopy, ultraviolet–visible spectroscopy, photoluminescence (PL), and cyclic voltammetry. These polymers show highly thermal stability, losing little of their weights when heated to 360 °C. The conjugated copolymers exhibit liquid crystallinity at elevated temperature. The existence of the chromophoric terphenyl core endows the copolymers with high PL and the polymer P(P(6)CN‐alt‐Cz containing carbazolylene unit can emit more pure blue light. All the copolymer films with low band gaps about 2.3–2.4 eV undergo reversible oxidation and reduction processes, significantly lower than the band gap of poly(p‐phenylene). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 434–442, 2010 相似文献