全文获取类型
收费全文 | 12284篇 |
免费 | 2055篇 |
国内免费 | 1737篇 |
专业分类
化学 | 9007篇 |
晶体学 | 152篇 |
力学 | 742篇 |
综合类 | 127篇 |
数学 | 1596篇 |
物理学 | 4452篇 |
出版年
2024年 | 12篇 |
2023年 | 173篇 |
2022年 | 264篇 |
2021年 | 350篇 |
2020年 | 427篇 |
2019年 | 442篇 |
2018年 | 391篇 |
2017年 | 381篇 |
2016年 | 544篇 |
2015年 | 567篇 |
2014年 | 710篇 |
2013年 | 900篇 |
2012年 | 1068篇 |
2011年 | 1217篇 |
2010年 | 876篇 |
2009年 | 892篇 |
2008年 | 1018篇 |
2007年 | 868篇 |
2006年 | 799篇 |
2005年 | 609篇 |
2004年 | 457篇 |
2003年 | 361篇 |
2002年 | 382篇 |
2001年 | 336篇 |
2000年 | 301篇 |
1999年 | 253篇 |
1998年 | 194篇 |
1997年 | 170篇 |
1996年 | 196篇 |
1995年 | 170篇 |
1994年 | 107篇 |
1993年 | 104篇 |
1992年 | 86篇 |
1991年 | 84篇 |
1990年 | 65篇 |
1989年 | 65篇 |
1988年 | 39篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 25篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Linjing Tong Yuhong Lin Xiaoxue Kou Yujian Shen Prof. Yong Shen Prof. Siming Huang Prof. Fang Zhu Prof. Guosheng Chen Prof. Gangfeng Ouyang 《Angewandte Chemie (International ed. in English)》2023,62(13):e202218661
Mimicking the bioactivity of native enzymes through synthetic chemistry is an efficient means to advance the biocatalysts in a cell-free environment, however, remains long-standing challenges. Herein, we utilize structurally explicit hydrogen-bonded organic frameworks (HOFs) to mimic photo-responsive oxidase, and uncover the important role of pore environments on mediating oxidase-like activity by means of constructing isostructural HOFs. We discover that the HOF pore with suitable geometry can stabilize and spatially organize the catalytic substrate into a favorable catalytic route, as with the function of the native enzyme pocket. Based on the desirable photo-responsive oxidase-like activity, a visual and sensitive HOFs biosensor is established for the detection of phosphatase, an important biomarker of skeletal and hepatobiliary diseases. This work demonstrates that the pore environments significantly influence the nanozymes’ activity in addition to the active center. 相似文献
92.
Feifan Li Xinyang Mu Xueqing Tang Ge Song Hongzhao Sun Xiuling Zha Peiyan Sun Jianhui Fang Dongmei Hu Shan Cong Zhigang Zhao 《Angewandte Chemie (International ed. in English)》2023,62(12):e202218055
Non-metallic materials have emerged as a new family of active substrates for surface-enhanced Raman scattering (SERS), with unique advantages over their metal counterparts. However, owing to their inefficient interaction with the incident wavelength, the Raman enhancement achieved with non-metallic materials is considerably lower with respect to the metallic ones. Herein, we propose colourful semiconductor-based SERS substrates for the first time by utilizing a Fabry-Pérot cavity, which realize a large freedom in manipulating light. Owing to the delicate adjustment of the absorption in terms of both frequency and intensity, resonant absorption can be achieved with a variety of non-metal SERS substrates, with the sensitivity further enhanced by ≈100 times. As a typical example, by introducing a Fabry-Pérot-type substrate fabricated with SiO2/Si, a rather low detection limit of 10−16 M for the SARS-CoV-2S protein is achieved on SnS2. This study provides a realistic strategy for increasing SERS sensitivity when semiconductors are employed as SERS substrates. 相似文献
93.
Boosting Hydrogen Peroxide Electrosynthesis via Modulating the Interfacial Hydrogen-Bond Environment
Yushuang Fang Yu Fan Kunchi Xie Wangxin Ge Yihua Zhu Zhiwen Qi Zhen Song Hongliang Jiang Chunzhong Li 《Angewandte Chemie (International ed. in English)》2023,62(27):e202304413
Designing highly efficient and stable electrode-electrolyte interface for hydrogen peroxide (H2O2) electrosynthesis remains challenging. Inhibiting the competitive side reaction, 4 e− oxygen reduction to H2O, is essential for highly selective H2O2 electrosynthesis. Instead of hindering excessive hydrogenation of H2O2 via catalyst modification, we discover that adding a hydrogen-bond acceptor, dimethyl sulfoxide (DMSO), to the KOH electrolyte enables simultaneous improvement of the selectivity and activity of H2O2 electrosynthesis. Spectral characterization and molecular simulation confirm that the formation of hydrogen bonds between DMSO and water molecules at the electrode-electrolyte interface can reduce the activity of water dissociation into active H* species. The suitable H* supply environment hinders excessive hydrogenation of the oxygen reduction reaction (ORR), thus improving the selectivity of 2 e− ORR and achieving over 90 % selectivity of H2O2. This work highlights the importance of regulating the interfacial hydrogen-bond environment by organic molecules as a means of boosting electrochemical performance in aqueous electrosynthesis and beyond. 相似文献
94.
Keming Song Xiang Wang Zhengkun Xie Zhiwei Zhao Zhe Fang Zhengfeng Zhang Jun Luo Pengfei Yan Zhangquan Peng Weihua Chen 《Angewandte Chemie (International ed. in English)》2023,62(10):e202216450
Solid-electrolyte interphase (SEI) seriously affects battery's cycling life, especially for high-capacity anode due to excessive electrolyte decomposition from particle fracture. Herein, we report an ultrathin SEI (3–4 nm) induced by Cu+-tailored double electrical layer (EDL) to suppress electrolyte consumption and enhance cycling stability of CuS anode in sodium-ion batteries. Unique EDL with SO3CF3-Cu complex absorbing on CuS in NaSO3CF3/diglyme electrolyte is demonstrated by in situ surface-enhanced Raman, Cyro-TEM and theoretical calculation, in which SO3CF3-Cu could be reduced to CuF2-rich SEI. Dispersed CuF2 and F-containing compound can provide good interfacial contact for formation of ultrathin and stable SEI film to minimize electrolyte consumption and reduce activation energy of Na+ transport. As a result, the modified CuS delivers high capacity of 402.8 mAh g−1 after 7000 cycles without capacity decay. The insights of SEI construction pave a way for high-stability electrode. 相似文献
95.
Guangcong Zhang Qiaomei Chen Zhou Zhang Jie Fang Chaowei Zhao Yen Wei Weiwei Li 《Angewandte Chemie (International ed. in English)》2023,62(4):e202216304
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a widely used hole transporting layer (HTL) in organic solar cells (OSCs), but its acidity severely reduces the stability of devices. Until now, very few HTLs were developed to replace PEDOT:PSS toward stable and high-performance OSCs. Herein, a new cobalt-lanthanum (Co-La) inorganic system was reported as HTL to show a high conversion efficiency (PCE) of 18.82 %, which is among the top PCEs in binary OSCs. Since electron-rich outer shell of La atom can interact with Co atom to form charge transfer complex, the work function and conductivity of the Co-La system could be simultaneously enhanced compared to Co or La-based HTLs. This Co-La system could also be applied into other OSCs to show high performance. All these results demonstrate that binary Co-La systems as HTL can efficiently tackle the issue in hole transporting and show powerful application in OSCs to replace PEDOT:PSS. 相似文献
96.
ChangYan Hu Dr. Ying Li Dr. Dong Wang Dr. Chunjin Wu Feng Chen Linghong Zhang Prof. Fang Wan Prof. Weibo Hua Prof. Yan Sun Prof. Benhe Zhong Dr. Zhenguo Wu Prof. Xiaodong Guo 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312310
Na2Ti6O13 (NTO) with high safety has been regarded as a promising anode candidate for sodium-ion batteries. In the present study, integrated modification of migration channels broadening, charge density re-distribution, and oxygen vacancies regulation are realized in case of Nb-doping and have obtained significantly enhanced cycling performance with 92 % reversible capacity retained after 3000 cycles at 3000 mA g−1. Moreover, unexpected low-temperature performance with a high discharge capacity of 143 mAh g−1 at 100 mA g−1 under −15 °C is also achieved in the full cell. Theoretical investigation suggests that Nb preferentially replaces Ti3 sites, which effectively improves structural stability and lowers the diffusion energy barrier. What's more important, both the in situ X-ray diffraction (XRD) and in situ Raman furtherly confirm the robust spring effect of the Ti−O bond, making special charge compensation mechanism and respective regulation strategy to conquer the sluggish transport kinetics and low conductivity, which plays a key role in promoting electrochemical performance. 相似文献
97.
Ziqi Zhu Di Zhang Tongtong Xiao Yu-Hui Fang Xiao Xiao Xiao-Ge Wang Prof. Shang-Da Jiang Prof. Dahui Zhao 《Angewandte Chemie (International ed. in English)》2023,62(49):e202314900
Stable carbon-based polyradicals exhibiting strong spin-spin coupling and slow depolarization processes are particularly attractive functional materials. A new molecular motif synthesized by a convenient method that allows the integration of stable, high-spin radicals to (hetero)aromatic polycycles has been developed, as illustrated by a non-Kekulé diradical showing a triplet ground state with long persistency (τ1/2≈31 h) in air. Compared to the widely used 1,3-phenylene, the newly designed (diaza)pyrene-4,10-diyl moiety is for the first time demonstrated to confer ferromagnetic (FM) spin coupling, allowing delocalized non-disjoint SOMOs. With the X-ray crystallography unambiguously proving the diradical structure, the triplet ground state was thoroughly characterized. A large ΔES-T of 1.1 kcal/mol, proving the strong FM coupling effect, was revealed consistently by superconducting quantum interference device (SQUID) measurements and variable-temperature electron paramagnetic resonance (EPR) spectroscopy, while the zero-field splitting and triplet nutation characters were examined by continuous-wave and pulsed EPR spectroscopy. A millisecond spin-lattice relaxation time was also detected. The current study not only offers a new molecular motif enabling FM coupling between carbon-based spins, but more importantly presents a general method for installing stable polyradicals into functional π-systems. 相似文献
98.
Ping Li Yuanyuan Ou Zilong Zhang Wenwen Wang Xu Ji Minfeng Fang Qian Li 《Journal of separation science》2023,46(9):2200944
As a famous traditional Chinese formula, Danshen Decoction has the potential to relieve the pain of pulmonary arterial hypertension patients, however, the functional components remain unknown. Herein, we reported a method to screen the functional components in Danshen Decoction targeting endothelin receptor A, an accepted target for the treatment of the disease. The receptor was functionalized on the macroporous silica gel through an epidermal growth factor receptor fusion tag and its covalent inhibitor. Using the affinity gel as the stationary phase, the bioactive compound was identified as salvianolic acid B by mass spectrometry. The binding kinetic parameter (dissociation rate constants kd) of salvianolic acid B with the receptor was determined via peak profiling. Using the specific ligands of the receptor as probes, the binding configuration prediction of salvianolic acid B with the receptor was performed by molecular dynamics simulation. Our results indicated that salvianolic acid B is a potential bioactive compound in Danshen Decoction targeting the receptor. This work showed that receptor chromatography in combination with molecular dynamics simulation is applicable to predicting the binding kinetics and configuration of a ligand to a receptor, providing crucial insight for the rational design of drugs that recognize functional proteins. 相似文献
99.
本文报导了在前人基础上改进的碳酸盐岩(白云石-方解石)地质样品钙同位素化学分离方案。通过对比云南永善桧溪剖面白云岩-灰岩过渡岩性在不同浓度盐酸下淋洗结果,确定了4N浓度盐酸能有效富集白云石-方解石体系中的钙元素,且热电离质谱(TIMS)测试结果显示4N盐酸与1.6N盐酸淋洗方案处理后钙同位素测试结果一致,表明在相同测试精度的情况下,针对白云石-方解石体系下碳酸盐岩地质样品化学分离方案能提高化学分离效率。本文进一步结合青藏高原研究热点问题,对钙同位素在青藏高原地质样品的应用前景进行了分析,分析表明,钙同位素在青藏高原隆升前古海洋环境重建、隆升期构造活动恢复及隆升后火成岩来源示踪上具有广泛应用前景。 相似文献
100.
石膏在我国储量丰富,应用广泛,快速准确分析其成分含量对石膏资源的综合利用具有重要意义。针对酸溶法无法测定SiO2,碱熔法无法测定K2O、Na2O的问题,本文建立一种偏硼酸锂-四硼酸锂熔融-电感耦合等离子体发射光谱法同时测定石膏中CaO、SO3、Al2O3、Fe2O3、MgO、TiO2、K2O、Na2O、SiO2含量。实验优化了熔剂用量、熔融温度,结果表明采用试样与偏硼酸锂-四硼酸锂混合熔剂质量比例1:5,在铂金坩埚中1000 ℃熔融10 min,在超声条件下,于50 mL 10 %盐酸中浸取熔融物,能够有效分解试样而浸取待测组分。向标准溶液系列中加入偏硼酸锂-四硼酸锂-盐酸基体溶液以消除基体对测试结果的影响。各待测组分的校准曲线的相关性系数均大于0.9990,方法检出限在3~292 μg/g范围内;采用实验方法分别对国家一级标准物质GBW03109a、GBW03110和实际样品进行测定,标准物质的5次平行测试的相对标准偏差在0.14 %~8.86 %之间,测定结果的相对误差在0.03~8.75 %之间,测试结果与标准值无显著性差异;实际样品中各成分测定值的RSD(n=5)为0.24~8.80 %。该方法操作简单、准确度高、精密度好、检出限低,可以同时测定石膏中的多组分含量,能够为石膏资源综合利用调查评价提供一定的技术支撑 。 相似文献