全文获取类型
收费全文 | 2535篇 |
免费 | 52篇 |
国内免费 | 3篇 |
专业分类
化学 | 1537篇 |
晶体学 | 22篇 |
力学 | 69篇 |
数学 | 394篇 |
物理学 | 568篇 |
出版年
2023年 | 12篇 |
2022年 | 36篇 |
2021年 | 49篇 |
2020年 | 35篇 |
2019年 | 32篇 |
2018年 | 70篇 |
2017年 | 73篇 |
2016年 | 64篇 |
2015年 | 80篇 |
2014年 | 72篇 |
2013年 | 118篇 |
2012年 | 166篇 |
2011年 | 157篇 |
2010年 | 100篇 |
2009年 | 61篇 |
2008年 | 121篇 |
2007年 | 121篇 |
2006年 | 99篇 |
2005年 | 290篇 |
2004年 | 241篇 |
2003年 | 157篇 |
2002年 | 49篇 |
2001年 | 44篇 |
2000年 | 38篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 20篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 17篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 19篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1968年 | 5篇 |
1961年 | 3篇 |
排序方式: 共有2590条查询结果,搜索用时 328 毫秒
991.
Lucas Andreo Carla A. Soldera Beatriz Guimares Ribeiro Patrick Raoul Vicente de Matos Paola Bindes Sousa Weslley Wallace de Alcntara Araújo Amorim Anna Carolina Ratto Tempestini Horliana Sandra Kalil Bussadori Kristianne Porta Santos Fernandes Raquel Agnelli Mesquita‐Ferrari 《Photochemistry and photobiology》2019,95(3):879-885
A peripheral nerve injury (PNI) can result in motor or sensory disorders. Low‐level laser therapy (LLLT) has demonstrated positive results as a treatment option for PNI. Wistar rats were divided into five groups: Control, Injury, Injury + LLLTn (nerve), Injury + LLLTm (muscle) and Injury + LLLTn + m (nerve and muscle irradiation). The groups were analyzed after one, two, three and four weeks. PNI was achieved by crushing the sciatic nerve. Laser treatment (780 nm, 3.2 J) was realized over the nerve and/or tibialis anterior muscle. In gait analyses, the groups irradiated over the nerve demonstrated an improvement after two weeks. In the analysis of mechanical sensitivity, the Injury + LLLTn demonstrated a reduction after one week in comparison with Injury group; the Injury + LLLTn + m and Injury + LLLTm demonstrated an increase after two weeks in comparison with Injury group; and the irradiated groups demonstrated a reduction in nociception after four weeks in comparison with Injury group. In the analysis of muscle atrophy, the Injury + LLLTn demonstrated more muscle mass after two weeks. LLLT improves functional aspects related to gait, mechanical sensitivity and muscle mass, with better results regarding motor aspects and muscle mass when administered over the injured nerve and better results regarding sensory aspects when administered over the muscle. 相似文献
992.
Martina Costa Cerqueira Pinto Nathany Lisbôa de Souza e Castro Eliane Pereira Cipolatti Roberto Fernandez‐Lafuente Evelin Andrade Manoel Denise Maria Guimarães Freire José Carlos Pinto 《大分子反应工程》2019,13(1)
Core–shell polymer supports with different morphological features and compositions are prepared through combined suspension and emulsion polymerizations. It is shown that proper manipulation of the divinylbenzene (DVB) feed content allows for maximization of specific areas, porosities, and mechanical resistances. Additionally, it is shown that feeding of previously prepared miniemulsions leads to core–shell particles with smaller specific areas, due to less efficient coating of the cores. Particularly, the combined manipulation of polymerization times and DVB feed compositions allows for production of particles with pronounced specific area (50 m2 g?1) and porosity (0.30 cm3 g?1). Produced core–shell polymer particles are employed as supports for the immobilization of lipase B from Candida antarctica, and the obtained enzymatic activities for both hydrolysis (A hyd) and esterification (A est) reactions are very high (A hyd = 34.7 ± 3.8 U/g; A est = 3564.6 ± 581 U/g), even when compared to activities obtained using the reference commercial biocatalyst Novozym 435 (A hyd = 7.6 ± 1.8 U/g, A est = 2384.7 ± 307.2 U/g). Finally, biocatalysts prepared with the core–shell supports present higher enzymatic activities than biocatalysts prepared with supports of higher specific area obtained through conventional emulsion polymerizations, indicating that the porous structure of the shell can be beneficial for the immobilization and activity of the enzymes. 相似文献
993.
994.
995.
Tanka Raj Rana JunHo Kim Jun-Hyoung Sim Kee-Jeong Yang Dae-Hwan Kim Jin-Kyu Kang 《Current Applied Physics》2017,17(10):1353-1360
Post deposition treatment (PDT) for Cu2ZnSn(S,Se)4 (CZTSSe) was carried out by simply dipping the absorber into the KF solution at 80 °C. The dipping time of absorber in KF solution was found to be crucial to device parameters of CZTSSe solar cell. The K-doping improved the solar cell efficiency from 4.4% to 7.6% by 1 min dipping whereas the longer than 5 min dipping solar cells showed distorted kink J-V curves. The activation energy of CZTSSe solar cell was increased upto 1 min KF treatment from 0.83 eV to 0.92 eV which indicates interface recombination is reduced significantly. However, the activation energies of 5 min and 10 min dipping solar cells were found to be 0.81 eV and 0.63 eV where dominant recombination was interface recombination. Furthermore, trap energies of 49 meV and 298 meV of pristine CZTSSe solar cell were modified to 33 meV and 117 meV for 1 min treated CZTSSe solar cell. Trap energies of 5 min were calculated to be 112 meV and 147 meV. The proper KF doping passivated the shallow as well as deep defects of CZTSSe solar cell which is reflected in photovoltaic performances directly. 相似文献
996.
We propose a model of random diffusion to investigate flow fluctuations in complex networks. We derive an analytical law showing that the dependence of fluctuations with the mean traffic in a network is ruled by the delicate interplay of three factors, respectively, of dynamical, topological and statistical nature. In particular, we demonstrate that the existence of a power-law scaling characterizing the flow fluctuations at every node in the network cannot be claimed. We show the validity of this scaling breakdown under quite general topological and dynamical situations by means of different traffic algorithms and by analyzing real data. 相似文献
997.
We study nonequilibrium dephasing in an electronic Mach-Zehnder interferometer. We demonstrate that the shot noise at the beam splitter of the interferometer generates an ensemble of nonequilibrium electron density configurations and that electron interactions induce configuration-specific phase shifts of an interfering electron. The resulting dephasing exhibits two characteristic features, a lobe pattern in the visibility and phase jumps of pi, in good agreement with experimental data. 相似文献
998.
J. R. Garbin D. M. B. P. Milori D. V. Magalhães M. Anwar M. Ahmed A. Bebeachibuli S. T. Müller V. S. Bagnato 《Laser Physics》2008,18(2):144-148
Laser cooling and trapping of neutral atoms has been employed for the measurement of the total electron impact cross sections of the ground state 62 S 1/2 of 133Cs atoms in the energy range from 80 to 500 eV. The total electron impact cross sections of the cold Cs atoms in the MOT were measured by observing the decay of the MOT after the interaction with the electron beam, and were found to depend only on the electron flux and not on the total number of atoms in the MOT. We confirm and extend the existing data on these measurements. 相似文献
999.
R. Muhammad J. Ramirez-Serrano K.M.F. Magalhes R. Paiva R. Shiozaki J. Weiner V.S. Bagnato 《Optics Communications》2008,281(19):4926-4930
We study the loading of sodium atoms into a magneto-optical trap from current-controlled sodium metal dispensers. Contrary to what was previously reported [V. Wippel, C. Binder, W. Huber, L. Windholz, M. Allegrini, F. Fuso, E. Arimondo, Eur. Phys. J. D 17 (2001) 285] we demonstrate a significantly higher number of trapped atoms that make Na dispensers a feasible source of atoms for cold-atom studies. The inherent rise in pressure that naturally arises from metal dispensers as they are heated to release atoms is partially controlled by placing the metal dispensers near the pumping port where an ion pump is connected. We also study the effects of placing the sodium dispensers at different distances from the main vacuum chamber where the atoms are trapped and the effectiveness of using a Zeeman slower to cool the atoms as they emerge from the dispensers. We observe trapping of up to 1.9 × 108 atoms, which is significantly higher by almost three orders of magnitude than previously reported experiments. 相似文献
1000.
Tnia Laranjeira Ana Costa Catarina Faria-Silva Daniela Ribeiro Jos Miguel P. Ferreira de Oliveira Sandra Simes Andreia Ascenso 《Molecules (Basel, Switzerland)》2022,27(5)
Tomato producing and processing industries present undoubted potential for industrial discarded products valorization whether due to the overproduction of fresh tomatoes or to the loss during processing. Although tomato by-products are not yet considered a raw material, several studies have suggested innovative and profitable applications. It is often referred to as “tomato pomace” and is quite rich in a variety of bioactive compounds. Lycopene, vitamin C, β-carotene, phenolic compounds, and tocopherol are some of the bioactives herein discussed. Tomato by-products are also rich in minerals. Many of these compounds are powerful antioxidants with anti-inflammatory properties besides modulating the immune system. Several researchers have focused on the possible application of natural ingredients, especially those extracted from foods, and their physiological and pharmacological effects. Herein, the effects of processing and further applications of the bioactive compounds present in tomato by-products were carefully reviewed, especially regarding the anti-inflammatory and anti-cancer effects. The aim of this review was thus to highlight the existing opportunities to create profitable and innovative applications for tomato by-products in health context. 相似文献