全文获取类型
收费全文 | 9988篇 |
免费 | 430篇 |
国内免费 | 87篇 |
专业分类
化学 | 6808篇 |
晶体学 | 91篇 |
力学 | 264篇 |
综合类 | 1篇 |
数学 | 1731篇 |
物理学 | 1610篇 |
出版年
2023年 | 77篇 |
2022年 | 56篇 |
2021年 | 182篇 |
2020年 | 209篇 |
2019年 | 250篇 |
2018年 | 158篇 |
2017年 | 159篇 |
2016年 | 384篇 |
2015年 | 288篇 |
2014年 | 320篇 |
2013年 | 603篇 |
2012年 | 607篇 |
2011年 | 653篇 |
2010年 | 453篇 |
2009年 | 404篇 |
2008年 | 586篇 |
2007年 | 630篇 |
2006年 | 494篇 |
2005年 | 547篇 |
2004年 | 440篇 |
2003年 | 350篇 |
2002年 | 287篇 |
2001年 | 125篇 |
2000年 | 95篇 |
1999年 | 67篇 |
1998年 | 72篇 |
1997年 | 88篇 |
1996年 | 99篇 |
1995年 | 89篇 |
1994年 | 80篇 |
1993年 | 95篇 |
1992年 | 74篇 |
1991年 | 76篇 |
1990年 | 69篇 |
1989年 | 64篇 |
1988年 | 48篇 |
1987年 | 54篇 |
1986年 | 64篇 |
1985年 | 102篇 |
1984年 | 99篇 |
1983年 | 77篇 |
1982年 | 66篇 |
1981年 | 70篇 |
1980年 | 62篇 |
1979年 | 64篇 |
1978年 | 67篇 |
1977年 | 41篇 |
1976年 | 40篇 |
1975年 | 50篇 |
1974年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Pekárek Stanislav Mikeš Jan Červenka Milan Hanuš Ondřej 《Plasma Chemistry and Plasma Processing》2021,41(3):779-792
Plasma Chemistry and Plasma Processing - We investigated the air supply mode effects on ozone production of the surface dielectric barrier discharge in the cylindrical configuration. The air into... 相似文献
43.
Designs, Codes and Cryptography - In this article we generalize the concepts that were used in the PhD thesis of Drudge to classify Cameron–Liebler line classes in PG $$(n,q), n\ge 3$$ , to... 相似文献
44.
Dr. Swati Deswal Rishukumar Panday Dr. Dipti R. Naphade Prashant Dixit Dr. Balu Praveenkumar Dr. Jan K. Zaręba Prof. Dr. Thomas D. Anthopoulos Prof. Dr. Satishchandra Ogale Prof. Dr. Ramamoorthy Boomishankar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(33):e202200751
Bismuth containing hybrid molecular ferroelectrics are receiving tremendous attention in recent years owing to their stable and non-toxic composition. However, these perovskite-like structures are primarily limited to ammonium cations. Herein, we report a new phosphonium based discrete perovskite-like hybrid ferroelectric with a formula [Me(Ph)3P]3[Bi2Br9] ( MTPBB ) and its mechanical energy harvesting capability. The Polarization-Electric field (P-E) measurements resulted in a well-defined ferroelectric hysteresis loop with a remnant polarization value of 2.1 μC cm−2. Piezoresponse force microscopy experiments enabled visualization of the ferroelectric domain structure and evaluation of the piezoelectric strain coefficient (d33) for an MTPBB single crystal and thin film sample. Furthermore, flexible devices incorporating MTPBB in polydimethylsiloxane (PDMS) matrix at various concentrations were fabricated and explored for their mechanical energy harvesting properties. The champion device with 20 wt % of MTPBB in PDMS rendered a maximum peak-to-peak open-circuit voltage of 22.9 V and a maximum power density of 7 μW cm−2 at an optimal load of 4 MΩ. Moreover, the potential of MTPBB -based devices in low power electronics was demonstrated by storing the harvested energy in various electrolytic capacitors. 相似文献
45.
Dr. Thangavel Vijayakanth Supriya Sahoo Premkumar Kothavade Vijay Bhan Sharma Prof. Dr. Dinesh Kabra Dr. Jan K. Zaręba Dr. Kadhiravan Shanmuganathan Prof. Dr. Ramamoorthy Boomishankar 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214984
Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A3BX6 type cyanometallate [Ph2(iPrNH)2P]3[Fe(CN)6] ( 1 ), which shows a ferroelectric saturation polarization (Ps) of 3.71 μC cm−2. Compound 1 exhibits a high electrostrictive coefficient (Q33) of 0.73 m4 C−2, far exceeding those of piezoceramics (0.034–0.096 m4 C−2). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt % 1 -TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 μW cm−2. 相似文献
46.
Light-Responsive Elastin-Like Peptide-Based Targeted Nanoparticles for Enhanced Spheroid Penetration
Dr. Duc H. T. Le Dr. Vusala Ibrahimova Sebastian A. H. van den Wildenberg Dr. Hanglong Wu Alba Fonseca Prof. Dr. Tomas Torres Dr. Elisabeth Garanger Dr. William P. J. Leenders Prof. Dr. Roland Brock Prof. Dr. Sébastien Lecommandoux Prof. Dr. Jan C. M. van Hest 《Angewandte Chemie (International ed. in English)》2023,62(24):e202300511
We describe here a near infrared light-responsive elastin-like peptide (ELP)-based targeted nanoparticle (NP) that can rapidly switch its size from 120 to 25 nm upon photo-irradiation. Interestingly, the targeting function, which is crucial for effective cargo delivery, is preserved after transformation. The NPs are assembled from (targeted) diblock ELP micelles encapsulating photosensitizer TT1-monoblock ELP conjugates. Methionine residues in this monoblock are photo-oxidized by singlet oxygen generated from TT1, turning the ELPs hydrophilic and thus trigger NP dissociation. Phenylalanine residues from the diblocks then interact with TT1 via π-π stacking, inducing the re-formation of smaller NPs. Due to their small size and targeting function, the NPs penetrate deeper in spheroids and kill cancer cells more efficiently compared to the larger ones. This work could contribute to the design of “smart” nanomedicines with deeper penetration capacity for effective anticancer therapies. 相似文献
47.
Philipp Seitz Dr. Manik Bhosale Luisa Rzesny Anselm Uhlmann Dr. Jan S. Wössner Robin Wessling Prof. Dr. Birgit Esser 《Angewandte Chemie (International ed. in English)》2023,62(43):e202306184
With their bent π-systems, cyclic conjugation and inherent cavities, conjugated nanohoops are attractive for organic electronics applications. For ease of processing and morphological stability, an incorporation into polymers is desirable, but to date was hampered with few exceptions by synthetic difficulties. We herein present a unique strategy for the synthesis of conjugated nanohoop polymers using a dibenzo[a,e]pentalene (DBP) as central connector. We demonstrate this versatility by synthesizing three electronically diverse copolymers with dithienyldiketo(pyrrolopyrrol), fluorene and carbazole comonomers, and report the first donor-acceptor nanohoop polymer. Optoelectronic investigations reveal the prevalence of cyclic or linear conjugation, depending on the comonomer unit, and ambipolar electrochemical properties through the antiaromatic character of the DBP units. As the first report on using conjugated nanohoops for charge storage as positive electrode materials, we show a significant improvement in battery performance in a nanohoop-containing polymer compared to an equivalent nanohoop-free reference polymer. We believe this study will pave the way for the synthesis of a diverse range of nanohoop polymers and further stimulate their exploration for charge storage in batteries. 相似文献
48.
Jan Leipert Philipp T. Kaulich Max K. Steinbach Britta Steer Konrad Winkels Christine Blurton Dr. Matthias Leippe Dr. Andreas Tholey 《Angewandte Chemie (International ed. in English)》2023,62(28):e202301969
While most nanoproteomics approaches for the analysis of low-input samples are based on bottom-up proteomics workflows, top-down approaches enabling proteoform characterization are still underrepresented. Using mammalian cell proteomes, we established a facile one-pot sample preparation protocol based on protein aggregation on magnetic beads and intact proteoform elution using 40 % formic acid. Performed on a digital microfluidics device, the workflow enabled sensitive analyses of single Caenorhabditis elegans nematodes, thereby increasing the number of proteoform identifications compared to in-tube sample preparation by 46 %. Label-free quantification of single nematodes grown under different conditions allowed to identify changes in the abundance of proteoforms not distinguishable by bottom-up proteomics. The presented workflow will facilitate proteoform-directed analysis on samples of limited availability. 相似文献
49.
Antonio J. LaPorte Jack E. Feldner Jan C. Spies Tom J. Maher Prof. Martin D. Burke 《Angewandte Chemie (International ed. in English)》2023,62(40):e202309566
Multifunctional organoboron compounds increasingly enable the simple generation of complex, Csp3-rich small molecules. The ability of boron-containing functional groups to modify the reactivity of α-radicals has also enabled a myriad of chemical reactions. Boronic esters with vacant p-orbitals have a significant stabilizing effect on α-radicals due to delocalization of spin density into the empty orbital. The effect of coordinatively saturated derivatives, such as N-methyliminodiacetic acid (MIDA) boronates and counterparts, remains less clear. Herein, we demonstrate that coordinatively saturated MIDA and TIDA boronates stabilize secondary alkyl α-radicals via σB-N hyperconjugation in a manner that allows site-selective C−H bromination. DFT calculated radical stabilization energies and spin density maps as well as LED NMR kinetic analysis of photochemical bromination rates of different boronic esters further these findings. This work clarifies that the α-radical stabilizing effect of boronic esters does not only proceed via delocalization of radical character into vacant boron p-orbitals, but that hyperconjugation of tetrahedral boron-containing functional groups and their ligand electron delocalizing ability also play a critical role. These findings establish boron ligands as a useful dial for tuning reactivity at the α-carbon. 相似文献
50.
Alexander D. Fusi Yudong Li Dr. A. Llopis-Lorente Dr. Tania Patiño Prof. Dr. Jan C. M. van Hest Dr. Loai K. E. A. Abdelmohsen 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214754
Unprecedented opportunities exist for the generation of advanced nanotechnologies based on synthetic micro/nanomotors (MNMs), such as active transport of medical agents or the removal of pollutants. In this regard, great efforts have been dedicated toward controlling MNM motion (e.g., speed, directionality). This was generally performed by precise engineering and optimizing of the motors′ chassis, engine, powering mode (i.e., chemical or physical), and mechanism of motion. Recently, new insights have emerged to control motors mobility, mainly by the inclusion of different modes that drive propulsion. With high degree of synchronization, these modes work providing the required level of control. In this Minireview, we discuss the diverse factors that impact motion; these include MNM morphology, modes of mobility, and how control over motion was achieved. Moreover, we highlight the main limitations that need to be overcome so that such motion control can be translated into real applications. 相似文献