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991.
11B (I=3/2) MAS NMR in the binary glass system xV2O5–B2O3 (x=0.053, 0.43) and the ternary glass system xV2O5–B2O3–PbO (0.1x1.5) has been investigated at room temperature. In the xV2O5–B2O3 glasses, one NMR line due to BO3 unit was observed. Meanwhile in the xV2O5–B2O3–PbO, two NMR lines which arise from BO3 and BO4 units were detected, where the appearance of BO4 units is produced by the presence of PbO. From the computer-simulation of the 11B NMR central transition line (m=−1/2↔1/2), the quadrupole parameters (e2qQ/h and η) for BO3 units in xV2O5–B2O3, and those for BO3 and BO4 units in xV2O5–B2O3–PbO were obtained as a function of x. As the V2O5 content increases in xV2O5–B2O3–PbO, the e2qQ/h and η values of the BO3− associated resonance are found to slightly decrease and increase, respectively. Meanwhile, the e2qQ/h and η values of BO4− associated resonance in xV2O5–B2O3–PbO are found to slightly increase and decrease, respectively. By comparing the intensities of the total transitions (m=−3/2↔−1/2,m=−1/2↔1/2, and 1/2↔3/2) for the 11B NMR line of BO3 and BO4 units contained in xV2O5–B2O3–PbO with those of respective standard samples of 0.053V2O5–B2O3 and NaBH4, the quantitative fractions of BO3 and BO4 in xV2O5–B2O3–PbO were obtained as a function of x. 相似文献
992.
Under the two assumptions that the origin of surface states may be different from that of bulk localized states within the gap and the density of surface states is sufficiently high, the validity of the double layer model on the amorphous semiconductor surface is investigated in comparison with the case of a crystal. It is suggested that the criteria concerning the double layer should be determined by the relative value of the surface states to that of bulk localized states. The existence of the double layer can be confirmed when the bulk localized state density n(Ef) is smaller than 1019 cm?3 eV?1. When n(Ef) is high at about 1020 cm?3 eV?1, surface states cannot be distinguished from the localized states within the gap. This double layer model is strongly supported by the results of previous experiments by others who have measured the dependence of the Schottky barrier height on the work function of metal and the dependence of the surface potential on the preparation conditions of a-SiH. 相似文献
993.
This study investigates the effect of viewer engagement on gifting items to a streamer in a live video streaming. Data were collected from AfreecaTV, a leading live video streaming platform in South Korea, to examine viewer engagement and gift-giving behavior. After analyzing 2,294,837 viewers over a three-month period, the empirical results provide evidence that viewer engagement is positively associated with gift-giving decisions. However, the impact of viewer engagement on the amount of gifts purchased is different depending on how the engagement is measured (i.e., by stream or by channel). This study empirically proves that the motive for socialization has a high correlation with gift-giving behavior, which is considered as commoditization of a viewer’s social interaction while consuming media. The study concludes with a discussion on practical implications for live video streaming services and suggestions for future research. 相似文献
994.
Pronouns are frequently dropped in Korean sentences, especially in text messages in the mobile phone environment. Restoring dropped pronouns can be a beneficial preprocessing task for machine translation, information extraction, spoken dialog systems, and many other applications. In this work, we address the problem of dropped pronoun recovery by resolving two simultaneous subtasks: detecting zero-pronoun sentences and determining the type of dropped pronouns. The problems are statistically modeled by encoding the sentence and classifying types of dropped pronouns using a recurrent neural network (RNN) architecture. Various RNN-based encoding architectures were investigated, and the stacked RNN was shown to be the best model for Korean zero-pronoun recovery. The proposed method does not require any manual features to be implemented; nevertheless, it shows good performance. 相似文献
995.
Fluorinated Polyimide as a Novel High‐Voltage Binder for High‐Capacity Cathode of Lithium‐Ion Batteries
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An increase in the energy density of lithium‐ion batteries has long been a competitive advantage for advanced wireless devices and long‐driving electric vehicles. Li‐rich layered oxide, xLi2MnO3?(1?x)LiMn1?y?zNiyCozO2, is a promising high‐capacity cathode material for high‐energy batteries, whose capacity increases by increasing charge voltage to above 4.6 V versus Li. Li‐rich layered oxide cathode however suffers from a rapid capacity fade during the high‐voltage cycling because of instable cathode–electrolyte interface, and the occurrence of metal dissolution, particle cracking, and structural degradation, particularly, at elevated temperatures. Herein, this study reports the development of fluorinated polyimide as a novel high‐voltage binder, which mitigates the cathode degradation problems through superior binding ability to conventional polyvinylidenefluoride binder and the formation of robust surface structure at the cathode. A full‐cell consisting of fluorinated polyimide binder‐assisted Li‐rich layered oxide cathode and conventional electrolyte without any electrolyte additive exhibits significantly improved capacity retention to 89% at the 100th cycle and discharge capacity to 223–198 mA h g?1 even under the harsh condition of 55 °C and high charge voltage of 4.7 V, in contrast to a rapid performance fade of the cathode coated with polyvinylidenefluoride binder. 相似文献
996.
Nonfullerene Electron Transporting Material Based on Naphthalene Diimide Small Molecule for Highly Stable Perovskite Solar Cells with Efficiency Exceeding 20%
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Su‐Kyo Jung Jin Hyuck Heo Dae Woon Lee Seung‐Chul Lee Seung‐Heon Lee Woojin Yoon Hoseop Yun Sang Hyuk Im Jong H. Kim O‐Pil Kwon 《Advanced functional materials》2018,28(20)
This study reports a new nonfullerene electron transporting material (ETM) based on naphthalene diimide (NDI) small molecules for use in high‐performance perovskite solar cells (PSCs). These solar cells simultaneously achieve high power conversion efficiency (PCE) of over 20% and long‐term stability. New NDI‐ID (N,N′‐Bis(1‐indanyl)naphthalene‐1,4,5,8‐tetracarboxylic diimide) consisting of an N‐substituted indane group having simultaneous alicyclic and aromatic characteristics is synthesized by a low‐cost, one‐step reaction, and facile purification method. The partially flexible characteristics of an alicyclic cyclopentene group on indane groups open the possibility of low‐temperature solution processing. The conformational rigidity and aromaticity of phenyl and alicyclic groups contribute to high temporal stability by strong secondary bonds. NDI‐ID has herringbone packed semiconducting NDI cores that exhibit up to 0.2 cm2 V?1 s?1 electron mobility in field effect transistors. The inverted PSCs based on CH(NH2)2PbI3–xBrx with NDI‐ID ETM exhibit very high PCEs of up to 20.2%, which is better than that of widely used PCBM (phenyl‐C61‐butyric acid methyl ester) ETM‐based PSCs. Moreover, NDI‐ID‐based PSCs exhibit very high long‐term temporal stability, retaining 90% of the initial PCE after 500 h at 100 °C with 1 sun illumination without encapsulation. Therefore, NDI‐ID is a promising ETM for highly efficient, stable PSCs. 相似文献
997.
Hak‐Sung Jung Kyung‐Jin Cho Yeonee Seol Yasuharu Takagi Andrew Dittmore Paul A. Roche Keir C. Neuman 《Advanced functional materials》2018,28(33)
Fluorescent nanodiamonds (FNDs) are promising bioimaging probes compared with other fluorescent nanomaterials such as quantum dots, dye‐doped nanoparticles, and metallic nanoclusters, due to their remarkable optical properties and excellent biocompatibility. Nevertheless, they are prone to aggregation in physiological salt solutions, and modifying their surface to conjugate biologically active agents remains challenging. Here, inspired by the adhesive protein of marine mussels, encapsulation of FNDs within a polydopamine (PDA) shell is demonstrated. These PDA surfaces are readily modified via Michael addition or Schiff base reactions with molecules presenting thiol or nitrogen derivatives. Modification of PDA shells by thiol terminated poly(ethylene glycol) (PEG‐SH) molecules to enhance colloidal stability and biocompatibility of FNDs is described. Their use as fluorescent probes for cell imaging is demonstrated; it is found that PEGylated FNDs are taken up by HeLa cells and mouse bone marrow‐derived dendritic cells and exhibit reduced nonspecific membrane adhesion. Furthermore, functionalization with biotin‐PEG‐SH is demonstrated and long‐term high‐resolution single‐molecule fluorescence based tracking measurements of FNDs tethered via streptavidin to individual biotinylated DNA molecules are performed. This robust polydopamine encapsulation and functionalization strategy presents a facile route to develop FNDs as multifunctional labels, drug delivery vehicles, and targeting agents for biomedical applications. 相似文献
998.
Solution‐Processed High‐Performance Tetrathienothiophene‐Based Small Molecular Blends for Ambipolar Charge Transport
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Sureshraju Vegiraju Chih‐Yu Lin Pragya Priyanka Deng‐Yi Huang Xian‐Lun Luo Hsiang‐Chi Tsai Shao‐Huan Hong Chia‐Jung Yeh Wei‐Chieh Lien Chien‐Lung Wang Shih‐Huang Tung Cheng‐Liang Liu Ming‐Chou Chen Antonio Facchetti 《Advanced functional materials》2018,28(28)
Four soluble dialkylated tetrathienoacene ( TTAR) ‐based small molecular semiconductors featuring the combination of a TTAR central core, π‐conjugated spacers comprising bithiophene ( bT ) or thiophene ( T ), and with/without cyanoacrylate ( CA ) end‐capping moieties are synthesized and characterized. The molecule DbT‐TTAR exhibits a promising hole mobility up to 0.36 cm2 V?1 s?1 due to the enhanced crystallinity of the microribbon‐like films. Binary blends of the p‐type DbT‐TTAR and the n‐type dicyanomethylene substituted dithienothiophene‐quinoid ( DTTQ‐11 ) are investigated in terms of film morphology, microstructure, and organic field‐effect transistor (OFET) performance. The data indicate that as the DbT‐TTAR content in the blend film increases, the charge transport characteristics vary from unipolar (electron‐only) to ambipolar and then back to unipolar (hole‐only). With a 1:1 weight ratio of DbT‐TTAR DTTQ‐11 in the blend, well‐defined pathways for both charge carriers are achieved and resulted in ambipolar transport with high hole and electron mobilities of 0.83 and 0.37 cm2 V?1 s?1, respectively. This study provides a viable way for tuning microstructure and charge carrier transport in small molecules and their blends to achieve high‐performance solution‐processable OFETs. 相似文献
999.
Inkjet Printing of Self‐Assembled 2D Titanium Carbide and Protein Electrodes for Stimuli‐Responsive Electromagnetic Shielding
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Mert Vural Abdon Pena‐Francesch Joan Bars‐Pomes Huihun Jung Hemanth Gudapati Christine B. Hatter Benjamin D. Allen Babak Anasori Ibrahim T. Ozbolat Yury Gogotsi Melik C. Demirel 《Advanced functional materials》2018,28(32)
2D titanium carbides (MXene) possess significant characteristics including high conductivity and electromagnetic interference shielding efficiency (EMI SE) that are important for applications in printed and flexible electronics. However, MXene‐based ink formulations are yet to be demonstrated for proper inkjet printing of MXene patterns. Here, tandem repeat synthetic proteins based on squid ring teeth (SRT) are employed as templates of molecular self‐assembly to engineer MXene inks that can be printed as stimuli‐responsive electrodes on various substrates including cellulose paper, glass, and flexible polyethylene terephthalate (PET). MXene electrodes printed on PET substrates are able to display electrical conductivity values as high as 1080 ± 175 S cm?1, which significantly exceeds electrical conductivity values of state‐of‐the‐art inkjet‐printed electrodes composed of other 2D materials including graphene (250 S cm?1) and reduced graphene oxide (340 S cm?1). Furthermore, this high electrical conductivity is sustained under excessive bending deformation. These flexible electrodes also exhibit effective EMI SE values reaching 50 dB at films with thicknesses of 1.35 µm, which mainly originate from their high electrical conductivity and layered structure. 相似文献
1000.
This study examined effect of a policy intervention that provides an upper limit for handset subsidies on users’ intention to change handset and households’ expenses on mobile telecommunications. The Korean government has prohibited mobile network providers from providing excessive subsidies for mobile handsets to attract subscribers since Nov. 2014 according to the mobile act. Using the exogenous variation, we estimate the impact of the policy on the intention to change handsets and expenses on handset installment, total mobile communications, and online content. The longitudinal data are from the 2014 to 2015 waves of the Korea Media Panel Survey. The mobile act lowered the predicted probability of switching handsets by 0.4% points. Moreover, the mobile act increased the predicted probability of any expense on handset installment by 7.5% points and had a significant impact on the amount of expenses on handset installment, with an increase of 7.8%. The mobile act lowered users’ willingness to switch handsets and increased spending on handset installment. This increased burden in handset installment might shrink the online content market, which has a large need for government support, as well as decrease consumers’ welfare. We assert that the policy intervention on handset subsidies is questionable with regard to both consumer welfare and the healthiness of the ICT ecosystem. 相似文献