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71.
The interaction energy between two similar plane parallel double layers is expanded in a series of tanh y0/4 and a general expression is introduced. The series converges very fast at moderate and low potentials. With the first four terms of the series a very high precision with six significant figures can be reached when the dimensionless surface potential y0 of the colloidal particles is less or equal to 3. 相似文献
72.
On MR lymphography, a new approach to the lung hilar and mediastinal nodes was developed in an animal model. Five rabbits were made to inhale iron colloid (cideferron) that was nebulized to aerosol. Two days after inhalation of the agent, the mediastinal lymph nodes decreased in signal on SE 2000/30 and SE 2000/60 images and proved to have iron on histological evaluation, whereas the popliteal nodes did not have any iron. Experimental results indicate that inhalational administration can deliver the agent to the pulmonary lymphatic system and has the potential of lung hilar and mediastinal MR lymphography. 相似文献
73.
采用柠檬酸三钠还原法制备胶体金,用胶体金标记和双抗体夹心免疫层析方法,建立对人绒毛膜促性腺激素的快速定量检测方法.该检测方法可以在15min内完成对HCG的定量检测,灵敏度可达25mIU/mL,线性范围25~10000mIU/mL.与人促黄体生成素(hLH)、人促甲状腺激素(hTSH)、人卵泡刺激素均无交叉反应,所建立的检测人绒毛膜促性腺激素的胶体金免疫层析方法,能快速、灵敏、特异、准确地检测样品中的人绒毛膜促性腺激素,在异位妊娠的早期诊断及过程监控中具有较为广阔的应用前景. 相似文献
74.
提出一种基于表面增强拉曼光谱的中药材肿节风饮片的检测方法。采用柠檬酸三钠还原硝酸银制备银溶胶,以银胶纳米粒子为增强基底测得肿节风茎切片的表面增强拉曼光谱(SERS)。发现银胶直接作用于药材表面的SERS信号明显增强,肿节风茎切片SERS光谱中在637,1 176,1 309,1 476,1 612 cm-1处都可观察到明显的拉曼特征峰。通过一阶导数拉曼光谱分析技术和对照品异嗪皮啶谱峰指认,可将获得的SERS峰位分别归属于吡喃酮环、甲氧基和酚羟基分子结构。研究结果表明,SERS技术可为肿节风和其他中草药的生产和质量监控提供一种快速、方便和直接的检测方法。 相似文献
75.
Interfacial energy is a fundamental physiochemical property of any multi-phase system. Among the most direct approaches for determining solid–liquid interfacial energy is a technique based on measuring the shape of grain boundary grooves in specimens subjected to a linear temperature gradient. This technique was adapted to crystallizing colloids in a gravitational field. Such colloids exhibit a freezing–melting phase transition and are important not only as self-assembling precursors to photonic crystals, but also as physical models of atomic and molecular systems. The grain boundary groove technique was tested using suspensions of sterically stabilized poly(methyl methacrylate) spheres, which have been shown to closely approximate the hard sphere potential. Whereas isotropic models did not fit grain boundary groove data well, the capillary vector model, which is suitable for both isotropic and anisotropic surface energies, produced γ110?=?0.58?±?0.05 k B T/σ2. This value of interfacial energy is in agreement with many of the published values for hard spheres, supporting the validity of our grain boundary groove technique adaptations to colloidal systems in a gravitational field. Finally, kinks observed in groove profiles suggest a minimum anisotropy parameter of ε?=?0.029 for hard spheres. 相似文献
76.
Xiaofeng Shi Yong‐Hyok Kwon Jun Ma Ronger Zheng Chunyan Wang H.‐D. Kronfeldt 《Journal of Raman spectroscopy : JRS》2013,44(1):41-46
A surface‐enhanced Raman scattering (SERS) active substrate for the detection of polycyclic aromatic hydrocarbons (PAHs) was developed, which used 25, 27‐dimercaptoacetic acid‐26, 28‐dihydroxy‐4‐terbutyl calix[4]arene (DMCX) to functionalize a gold colloid film. This SERS‐active substrate prepared by self‐assembly method exhibits a high sensitivity, especially for the detection of PAHs. With the use of this SERS‐active substrate and with the application of the shifted excitation Raman difference spectroscopy (SERDS) technique, Raman signals of pyrene and anthracene in aqueous solutions at low concentration level (500 pM) can be obtained. Moreover, because PAHs are blocked from being directly adsorbed on gold colloid by DMCX and the photochemical reactions of adsorbates are avoided, the Raman bands of PAHs adsorbed on DMCX‐fuctionalized gold colloid film can be one‐to‐one correspondence with those of solid PAHs, and additionally, this SERS‐active substrate can be easily cleaned and reused. The obtained results demonstrate that the DMCX‐functionalized gold colloid films prepared by self‐assembly method have great potential to be developed to an in situ PAHs detection substrate. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
77.
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79.
Dr. So-Yeon Park Sehoon Han Dr. Younghoon Kim Prof. Sohee Jung Prof. Dong Hoe Kim Dr. Gill Sang Han Prof. Hyun Suk Jung 《Chemphyschem》2019,20(20):2657-2661
Multiple exciton generation (MEG) has great potential to improve the Shockley-Queisser (S-Q) efficiency limitation for colloidal quantum dot (CQD) solar cells. However, MEG has rarely been observed in CQD solar cells because of the loss of carriers through the transport mechanism between adjacent QDs. Herein, we demonstrate that excess charge carriers produced via MEG can be efficiently extracted using monolayer PbS QDs. The monolayer PbS QDs solar cells exhibit α=1 in the light intensity dependence of the short-circuit current density Jsc (Jsc∝Iα) and an internal quantum efficiency (IQE) value of 100 % at 2.95 eV because of their very short charge extraction path. In addition, the measured MEG threshold is 2.23 times the bandgap energy (Eg), which is the lowest value in PbS QD solar cells. We believe that this approach can provide a simple method to find suitable CQD materials and design interface engineering for MEG. 相似文献
80.
Edyta Podstawka Pawe Kafarski Leonard M. Proniewicz 《Journal of Raman spectroscopy : JRS》2008,39(12):1726-1739
A comparative study of molecular structures of five L ‐proline (L ‐Pro) phosphonodipeptides: L ‐Pro‐NH‐C(Me,Me)‐PO3H2 (P1), L ‐Pro‐NH‐C(Me,iPr)‐PO3H2 (P2), L ‐Pro‐L ‐NH‐CH(iBu)‐PO3H2 (P3), L ‐Pro‐L ‐NH‐CH(PA)‐PO3H2 (P4) and L ‐Pro‐L ‐NH‐CH(BA)‐PO3H2 (P5) has been carried out using Raman and absorption infrared techniques of molecular spectroscopy. The interpretation of the obtained spectra has been supported by density functional theory calculations (DFT) at the B3LYP; 6–31 + + G** level using Gaussian 2003 software. The surface‐enhanced Raman scattering (SERS) on Ag‐sol in aqueous solutions of these phosphonopeptides has also been investigated. The surface geometry of these molecules on a silver colloidal surface has been determined by observing the position and relative intensity changes of the Pro ring, amide, phosphonate and so‐called spacer (−R) groups vibrations of the enhanced bands in their SERS spectra. Results show that P4 and P5 adsorb onto the silver as anionic molecules mainly via the amide bond (∼1630, ∼1533, ∼1248, ∼800 and ∼565 cm−1), Pro ring (∼956, ∼907 and ∼876 cm−1) and carboxylate group (∼1395 and ∼909 cm−1). Coadsorption of the imine nitrogen atom and PO group with the silver surface, possibly by formation of a weaker interaction with the metal, is also suggested by the enhancement of the bands at 1158 and 1248 cm−1. P1, P2 and P3 show two orientations of their main chain on the silver surface resulting from different interactions of the C CH3, NH and CONH fragments with this surface. Bonding to the Ag surface occurs mainly through the imino atom (1166 cm−1) for P2, while for P1 and P3 it occurs via the methyl group(s) (1194–1208 cm−1). The amide group functionality (CONH) is practically not involved in the adsorption process for P1 and P2, whereas the Cs P bonds do assist in the adsorption. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献