全文获取类型
收费全文 | 9442篇 |
免费 | 2187篇 |
国内免费 | 1393篇 |
专业分类
化学 | 7207篇 |
晶体学 | 174篇 |
力学 | 553篇 |
综合类 | 118篇 |
数学 | 1026篇 |
物理学 | 3944篇 |
出版年
2024年 | 12篇 |
2023年 | 283篇 |
2022年 | 341篇 |
2021年 | 490篇 |
2020年 | 578篇 |
2019年 | 541篇 |
2018年 | 450篇 |
2017年 | 406篇 |
2016年 | 537篇 |
2015年 | 649篇 |
2014年 | 700篇 |
2013年 | 820篇 |
2012年 | 982篇 |
2011年 | 956篇 |
2010年 | 657篇 |
2009年 | 694篇 |
2008年 | 730篇 |
2007年 | 589篇 |
2006年 | 539篇 |
2005年 | 409篇 |
2004年 | 302篇 |
2003年 | 217篇 |
2002年 | 207篇 |
2001年 | 152篇 |
2000年 | 139篇 |
1999年 | 110篇 |
1998年 | 90篇 |
1997年 | 70篇 |
1996年 | 60篇 |
1995年 | 44篇 |
1994年 | 38篇 |
1993年 | 42篇 |
1992年 | 33篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1966年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
1.
Yersak Thomas A. Hao Fang Kang Chansoon Salvador James R. Zhang Qinglin Malabet Hernando Jesus Gonzalez Cai Mei 《Journal of Solid State Electrochemistry》2022,26(3):709-718
Journal of Solid State Electrochemistry - In this study, hot pressing was evaluated as a method of cell fabrication to increase the energy density of next-generation all-solid-state batteries with... 相似文献
2.
Mathematical Programming - Convergence analysis of accelerated first-order methods for convex optimization problems are developed from the point of view of ordinary differential equation solvers. A... 相似文献
3.
Hao Lu Xiaodong Wang Hang Wang Andong Zhang Xinming Zheng Na Yu Zheng Tang Xinjun Xu Yahui Liu Ya-Nan Chen Zhishan Bo 《中国科学:化学(英文版)》2022,65(3):594-601
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs. 相似文献
4.
Jie Pan Yan Bao Hao Wang Fucong Lyu Lu Liu Chong Wang Xinxue Tang Jian Lu Yang Yang Li 《Particle & Particle Systems Characterization》2021,38(10):2100094
The high-entropy materials have raised much attention in recent years due to their extraordinary performances in mechanical, catalysis, energy storage fields. Herein, a new type of high-entropy hydroxides (e.g., NiFeCoMnAl(OH)x) that are amorphous and capable of broad solar absorption is reported. A facile one-pot co-precipitation method is employed to synthesize these amorphous high-entropy hydroxides (a-HEHOs) under ambient conditions. The a-HEHOs thus obtained display widely tunable bandgap (e.g., from 2.6 to 1.1 eV) due to their high-entropy and amorphous characteristics, enabling efficient light absorbance and photothermal conversion in the solar regime. Further solar water evaporation measurements show that the a-HEHOs delivered a considerable energy conversion efficiency of 55%, comparable to black titanium oxides that are synthesized using more complex and expensive methods. 相似文献
5.
Qiang Chenxu Hao Yuxin Zhang Wei Li Jinqiang Yang Shaowu Cao Yuteng 《应用数学和力学(英文版)》2021,42(11):1555-1570
Applied Mathematics and Mechanics - The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural... 相似文献
6.
Yuan Xin Zhang Shuren Zhong Xuanmeng Yuan Hao Song Dongfan Wang Xiaoyu Yu Hanyang Guo Zijian 《中国科学:化学(英文版)》2022,65(10):1978-1984
Science China Chemistry - Oncogenic KRAS reprograms pancreatic ductal adenocarcinoma (PDAC) cells to a state that is awfully resistant to apoptosis. An alternative coping strategy is to trigger a... 相似文献
7.
本研究探讨3.0T磁共振成像(MRI)结合X线钼靶诊断乳腺恶性肿瘤的价值。采用回顾性研究方法,选取乳腺肿块患者110例162个病灶,给予3.0T MRI及X线钼靶检查。经病理确诊为恶性病变101个;恶性病灶形态不规则、边缘毛刺、时间-信号强度曲线(TIC)类型Ⅲ型和早期增强率≥60%比例明显高于良性病灶(P<0.05),而分叶状比例和表观扩散系数(ADC)值明显低于良性病变(P<0.05);恶性病变X线钼靶表现:形态不规则、钙化、结构不对称和大导管征比例明显高于良性病变(P<0.05);MRI联合X线钼靶诊断乳腺恶性病变的灵敏性、准确性和阴性预测值明显高于MRI诊断(P<0.05)。3.0T MRI检查结合X线钼靶诊断乳腺恶性肿瘤有较好的价值。 相似文献
8.
9.
对硫化镉反蛋白石结构光子晶体薄膜进行了可控合成,用巯基乙酸修饰的纳米晶和P(St-MMA-SPMAP)高分子小球共组装,成功地构筑了反蛋白石结构并用于可见光光解水产氢。结果表明,在可见光(λ≥420 nm)照射下,Cd S-310反蛋白石结构薄膜的光解水产氢性能比硫化镉纳米颗粒提高了一倍。这主要是因为等级孔结构反蛋白石光子晶体特性对催化剂的光催化性能的提升:首先,反蛋白石的周期性结构增加了光子在材料中的传播,提高了催化剂对太阳光的利用率;同时,大孔孔壁是由纳米颗粒堆积而成的,在反应中提供了更多的反应活性位点;此外,孔结构有利于物质的传输和分子的吸附。 相似文献
10.
Since most of the control strategies for air-breathing hypersonic vehicles (AHVs) concentrate on the control-oriented models built at/around a specific working point, it is somewhat hard to extend them to the broader flight envelop. Aiming at the above deficiency, this paper formulates the dynamics of AHVs as several sub-models, which switch to each other in accordance with the flight condition and make up of the control-oriented switched model (COSM). With the aid of the COSM, two adaptive tracking controllers are proposed for the purposes of velocity tracking and altitude tracking, sequentially. By utilizing neural networks and designing robust control laws, the possible changes on the force and moment coefficients in the COSM are successfully handled. The time-varying inertia parameters of AHVs are also considered at design level. It is worth emphasizing that while this strategy is developed based on a switched model, the resulting control algorithm is continuous with no connection to the switching signal. Analysis indicates that both velocity and altitude tracking errors remain small within the whole flight envelop, which is further confirmed by a simulation study. 相似文献