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991.
Chunxia Jia Qing Wang Jianxin Ge Xiaofei Xu 《Journal of Thermal Analysis and Calorimetry》2014,116(2):1073-1081
Thermogravimetric (TG) data of oil sand obtained at Engineering Research Center of Oil Shale Comprehensive Utilization were studied to evaluate the kinetic parameters for Indonesian oil sand samples. Experiments were carried out at heating rates of 5, 15, and 25 °C min?1 in nitrogen, 10, 20, and 50 °C min?1 in oxygen atmosphere, respectively. The extent of char combustion was found out by relating TG data for pyrolysis and combustion with the ultimate analysis. Due to distinct behavior of oil shale during pyrolysis, TG curves were divided into three separate events: moisture release, devolatilization, and evolution of fixed carbon/char, where for each event, kinetic parameters, based on Arrhenius theory, were calculated. Coats–Redfern method, Flynn–Wall–Ozawa method, and distributed activation energy model method have been used to determine the activation energies of degradation. The methods are compared with regard to their characteristics and the ease of interpretation of the thermal kinetics. Activation energies of the samples were determined by three different methods and the results are discussed. 相似文献
992.
Meng Li Hong‐Ye Bai Zu‐Lin Da Xu Yan Chao Chen Jin‐Hui Jiang Wei‐Qiang Fan Wei‐Dong Shi 《Crystal Research and Technology》2015,50(3):244-249
CaFe2O4/MgFe2O4 nanowires with heterostructure had been successfully synthesized by electrospinning method. The obtained samples were systematically characterized by scanning electron microscopy (SEM), X‐Ray diffraction (XRD), UV–Vis diffuse reflectance spectra (UV‐Vis DR) and Environment scanning electron microscopy (ESEM). The novel CaFe2O4/MgFe2O4 nanowires exhibit an enhanced photocatalytic activity for degrading of tetracycline (TC) under visible light. Compared with bare CaFe2O4 or MgFe2O4 samples, the prepared CaFe2O4/MgFe2O4 (Ca:Mg:Fe = 3:2:10) composited nanowires show the best photocatalytic performance with a degradation efficiency of 40% after 150 min reaction time. This enhancement is attributed to the heterostructure of CaFe2O4/MgFe2O4 nanowires, which effectively repress the recombination of photo‐generated electrons and holes. Based on heterostructure and energy band positions, the enhancement of mechanism under visible‐light enhances the photocatalytic activity. 相似文献
993.
In this contribution, an electron acceptor attached diarylethene derivative was synthesized and fully characterized. The photochromic behavior was investigated in THF. Under exposure of UV and visible light cycles, the solution color can be switched between colorless and yellow smoothly. Fatigue resistance measurements could be repeated 50 times with an acceptable degradation. Due to the electron acceptor attached to the framework of diarylethene, the photo- and thermal-stability were enhanced both. A full-photo mode switch can be established based on the well-defined states by external excitation. The molecular structures of ring-open and ring-closed form were optimized by Dmol3. The distance between photocyclizing atoms in aptiparallel conformation meets the requirement for photochromic reaction. And the calculated absorption wavelengths were also in agreement with the experimental values. 相似文献
994.
Li Sun Chunlei Wang Ying Zhou Qiang Zhao Xu Zhang Jieshan Qiu 《Journal of Solid State Electrochemistry》2014,18(1):49-58
Activated nitrogen-doped carbons (ANCs) were prepared by carbonization/activation approach using aminated polyvinyl chloride (PVC) as precursor. ANCs exhibit larger porosities and higher specific surface areas than those of their nitrogen-free counterparts for the same KOH/carbon ratio. The specific surface area of ANC-1 is up to 1,398 m2 g?1 even at a low KOH/carbon ratio of 1:1. Fourier transform infrared spectroscopy investigation of the nitrogen-enriched resin precursor indicates the efficient dehydrochlorination of PVC by ethylenediamine at a low temperature. The nitrogen content and the population of nitrogen functionalities strongly depend on the KOH/carbon ratios and decrease drastically after KOH activation as seen from the elemental and X-ray photoelectron spectroscopy analysis. The surface concentration of N-6 and N-Q almost disappears and the dominant nitrogen groups become N-5 after KOH activation. The highest specific capacitance of ANCs is up to 345 F g?1 at a current density of 50 mA g?1 in 6 M KOH electrolyte. ANCs also exhibit a good capacitive behavior at a high scan rate of 200 mV s?1 and an excellent cyclability with a capacitance retention ratio as high as ~93 % at a current density of 2,000 mA g?1 for 5,000 cycles. 相似文献
995.
Rhodium(I)‐Catalyzed Decarbonylative Spirocyclization through CC Bond Cleavage of Benzocyclobutenones: An Efficient Approach to Functionalized Spirocycles 下载免费PDF全文
Dr. Tao Xu Nikolas A. Savage Prof. Dr. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2014,53(7):1891-1895
The rhodium‐catalyzed formation of all‐carbon spirocenters involves a decarbonylative coupling of trisubstituted cyclic olefins and benzocyclobutenones through C? C activation. The metal–ligand combination [{Rh(CO)2Cl}2]/P(C6F5)3 catalyzed this transformation most efficiently. A range of diverse spirocycles were synthesized in good to excellent yields and many sensitive functional groups were tolerated. A mechanistic study supports a hydrogen‐transfer process that occurs through a β‐H elimination/decarbonylation pathway. 相似文献
996.
Yaqin Xu Zhuyuan Zhang Dr. M. Monsur Ali Joanna Sauder Xudong Deng Karen Giang Sergio D. Aguirre Prof. Dr. Robert Pelton Prof. Dr. Yingfu Li Prof. Dr. Carlos D. M. Filipe 《Angewandte Chemie (International ed. in English)》2014,53(10):2620-2622
An odor‐based sensor system that exploits the metabolic enzyme tryptophanase (TPase) as the key component is reported. This enzyme is able to convert an odorless substrate like S‐methyl‐L ‐cysteine or L ‐tryptophan into the odorous products methyl mercaptan or indole. To make a biosensor, TPase was biotinylated so that it could be coupled with a molecular recognition element, such as an antibody, to develop an ELISA‐like assay. This method was used for the detection of an antibody present in nM concentrations by the human nose. TPase can also be combined with the enzyme pyridoxal kinase (PKase) for use in a coupled assay to detect adenosine 5′‐triphosphate (ATP). When ATP is present in the low μM concentration range, the coupled enzymatic system generates an odor that is easily detectable by the human nose. Biotinylated TPase can be combined with various biotin‐labeled molecular recognition elements, thereby enabling a broad range of applications for this odor‐based reporting system. 相似文献
997.
Clickable Periodic Mesoporous Organosilicas: Synthesis,Click Reactions,and Adsorption of Antibiotics 下载免费PDF全文
Dr. Jinsuo Gao Xueying Zhang Dr. Shutao Xu Prof. Feng Tan Prof. Xinyong Li Prof. Yaobin Zhang Prof. Zhenping Qu Prof. Xie Quan Dr. Jian Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1957-1963
Pharmaceutical antibiotics are not easily removed from water by conventional water‐treatment technologies and have been recognized as new emerging pollutants. Herein, we report the synthesis of clickable azido periodic mesoporous organosilicas (PMOs) and their use as adsorbents for the adsorption of antibiotics. Ethane‐bridged PMOs, functionalized with azido groups at different densities, were synthesized by the co‐condensation of 1,2‐bis(trimethoxysilyl)ethane (BTME) and 3‐azidopropyltrimethoxysilane (AzPTMS), in the presence of nonionic‐surfactant triblock‐copolymer P123, in an acidic medium. Four different alkynes were conjugated to azide‐terminated PMOs by means of an efficient click reaction. The clicked PMOs showed improved adsorption capacity (241 μg g?1) for antibiotics (ciprofloxacin hydrochloride) compared with azido‐functionalized PMOs because of the enhanced π–π stacking interactions. These results indicate that click reactions can introduce multifunctional groups onto PMOs, thus demonstrating the great potential of PMOs for environmental applications. 相似文献
998.
Back Cover: Two‐Dimensional Tetrathiafulvalene Covalent Organic Frameworks: Towards Latticed Conductive Organic Salts (Chem. Eur. J. 45/2014) 下载免费PDF全文
999.
Rationally Investigating the Influence of T1 Location on Electroluminescence Performance of Aryl Amine Modified Phosphine Oxide Materials 下载免费PDF全文
Chunmiao Han Liping Zhu Jing Li Fangchao Zhao Dr. Hui Xu Prof. Dongge Ma Prof. Pengfei Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16350-16359
The correspondence between triplet location effect and host‐localized triplet–triplet annihilation and triplet–polaron quenching effects was performed on the basis of a series of naphthyldiphenylamine (DPNA)‐modified phosphine oxide hosts. The number and ratio of DPNA and diphenylphosphine oxide was adjusted to afford symmetrical and unsymmetrical molecular structures and different electronic environments. As designed, the first triplet (T1) states were successfully localized on the specific DPNA chromophores. Owing to the meso‐ and multi‐insulating linkages, identical optical properties and comparable electrical performance was observed, including the same first singlet (S1) and T1 energy levels to support the similar singlet and triplet energy transfer and the close frontier molecular orbital energy levels. This established the basis of rational investigation on T1 location effect without interference from other optoelectronic factors. 相似文献
1000.
A Selective Release System Based on Dual‐Drug‐Loaded Mesoporous Silica for Nanoparticle‐Assisted Combination Therapy 下载免费PDF全文
Dr. Wenqian Wang Prof. Yongqiang Wen Prof. Liping Xu Prof. Hongwu Du Yabin Zhou Prof. Xueji Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7796-7802
A selective release system was demonstrated with a dual‐cargo loaded MSNs. When stimulated by different signals (UV or H+), this system could selectively release different kinds of cargoes individually. Furthermore, this system has been used to provide a combination of chemotherapy and biotherapy for cancer treatment. This controlled release system could be an important step in the development of more effective and sophisticated nanomedicine and nanodevices, due to the possibility of selective release of a complex multi‐drug. 相似文献