全文获取类型
收费全文 | 4879篇 |
免费 | 344篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 85篇 |
妇产科学 | 135篇 |
基础医学 | 998篇 |
口腔科学 | 43篇 |
临床医学 | 421篇 |
内科学 | 1096篇 |
皮肤病学 | 52篇 |
神经病学 | 586篇 |
特种医学 | 115篇 |
外科学 | 507篇 |
综合类 | 16篇 |
一般理论 | 2篇 |
预防医学 | 299篇 |
眼科学 | 101篇 |
药学 | 381篇 |
中国医学 | 8篇 |
肿瘤学 | 383篇 |
出版年
2024年 | 3篇 |
2023年 | 62篇 |
2022年 | 162篇 |
2021年 | 220篇 |
2020年 | 99篇 |
2019年 | 143篇 |
2018年 | 163篇 |
2017年 | 97篇 |
2016年 | 132篇 |
2015年 | 158篇 |
2014年 | 186篇 |
2013年 | 230篇 |
2012年 | 366篇 |
2011年 | 424篇 |
2010年 | 241篇 |
2009年 | 221篇 |
2008年 | 371篇 |
2007年 | 363篇 |
2006年 | 345篇 |
2005年 | 290篇 |
2004年 | 260篇 |
2003年 | 248篇 |
2002年 | 208篇 |
2001年 | 32篇 |
2000年 | 15篇 |
1999年 | 30篇 |
1998年 | 37篇 |
1997年 | 34篇 |
1996年 | 19篇 |
1995年 | 20篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有5249条查询结果,搜索用时 0 毫秒
61.
Irina Butnaru Maria Bruma Thomas Kopnick Joachim Stumpe 《Macromolecular chemistry and physics.》2013,214(21):2454-2464
The influence of different substituents on the optical properties of poly(amide imide)s and polyimides is systematically investigated. All of the polymers exhibit good solubility and film‐forming ability, high thermal stability, and glass transition temperatures of 162–209 °C for poly(amide imide)s and of 209–274 °C for polyimides. The optical transmittance of the films at 450 nm is above 80% for all the studied polyimides and poly(amide imide)s containing benzonitrile units linked in the 2,6‐position. The values of refractive index for poly(amide imide)s are in the range of 1.623–1.748 and for polyimides in the domain of 1.672–1.768.
62.
Irina V. Shemarova 《Critical reviews in microbiology》2013,39(3):141-156
The review considers the up to date achievements in the role of membrane phosphoinositides and keys enzymes of the lipid branch of the phosphoinositide signal pathway (PI-pathway) in unicellular eukaryotes. Particular attention is paid to mechanisms of phospholipase C (PLC) activation and the PLC interaction both with cell surface receptors and with the effector cytoplasm targets. The role of protein kinase C (PKC) in intracellular signaling and the relationship of the PI-pathway key enzymes with protein tyrosine kinases (PTK)-signaling and cAMP-protein kinase A (PKA) pathway are discussed. 相似文献
63.
64.
65.
Polyakov Andrey P. Mordovskiy Alexander V. Ratushnyy Mikhail V. Rebrikova Irina V. 《Oral and maxillofacial surgery》2021,25(2):271-277
Oral and Maxillofacial Surgery - Presently, the functional reconstruction of the tongue in patients after subtotal or total glossectomy with the removal of the oral floor muscles and spearing of... 相似文献
66.
Irina S. Vasil'eva Galina P. Shumakovich Maria E. Khlupova Roman B. Vasiliev Viktor V. Emets Vera A. Bogdanovskaya Olga V. Morozova Alexander I. Yaropolov 《RSC advances》2020,10(55):33010
The development of novel materials with improved functional characteristics for supercapacitor electrodes is of current concern and calls for elaboration of innovative approaches. We report on an eco-friendly enzymatic synthesis of a composite based on poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-walled carbon nanotubes (MWCNTs). The redox active compound, sodium 1,2-naphthoquinone-4-sulfonate (NQS), was used as a dopant for the backbone of the polymer. Oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) was catalyzed by a high redox potential laccase from the fungus Trametes hirsuta. Atmospheric oxygen served as an oxidant. A uniform thin layer of NQS-doped PEDOT formed on the surface of MWCNTs as a result of the enzymatic polymerization. The PEDOT–NQS/MWCNT composite showed a high specific capacitance of ca. 575 F g−1 at a potential scan rate of 5 mV s−1 and an excellent cycling stability within a potential window between −0.5 and 1.0 V, which makes it a promising electrode material for high-performance supercapacitors.The use of redox active NSQ as a dopant of PEDOT dramatically increases the specific capacitance and cyclic stability of enzymatically synthesized PEDOT–NSQ/MWCNT composite. 相似文献
67.
68.
69.
Jason C. Burton Shang Wang C. Allison Stewart Richard R. Behringer Irina V. Larina 《Biomedical optics express》2015,6(7):2713-2723
The understanding of the reproductive events and the molecular mechanisms regulating fertility and infertility in humans relies heavily on the analysis of the corresponding phenotypes in mouse models. While molecular genetic approaches provide significant insight into the molecular regulation of these processes, the lack of live imaging methods that allow for detailed visualization of the mouse reproductive organs limits our investigations of dynamic events taking place during the ovulation, the fertilization and the pre-implantation stages of embryonic development. Here we introduce an in vivo three-dimensional imaging approach for visualizing the mouse oviduct and reproductive events with micro-scale spatial resolution using optical coherence tomography (OCT). This method relies on the natural tissue optical contrast and does not require the application of any contrast agents. For the first time, we present live high-resolution images of the internal structural features of the oviduct, as well as other reproductive organs and the oocytes surrounded by cumulus cells. These results provide the basis for a wide range of live dynamic studies focused on understanding fertility and infertility.OCIS codes: (110.4500) Optical coherence tomography, (170.3880) Medical and biological imaging, (170.5380) Physiology 相似文献
70.
Periodontitis in Rats Induces Systemic Oxidative Stress That Is Controlled by Bone‐Targeted Antiresorptives 下载免费PDF全文
Sehkar Oktay Sasanka S. Chukkapalli Mercedes F. Rivera‐Kweh Irina M. Velsko L. Shannon Holliday Lakshmyya Kesavalu 《Journal of periodontology》2015,86(1):137-145
Background: Periodontitis is a chronic, polymicrobial inflammatory disease that degrades connective tissue and alveolar bone and results in tooth loss. Oxidative stress has been linked to the onset of periodontal tissue breakdown and systemic inflammation, and the success of antiresorptive treatments will rely on how effectively they can ameliorate periodontal disease–induced oxidative stress during oral infection. Methods: Rats were infected with polybacterial inoculum consisting of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, as an oral lavage every other week for 12 weeks. Daily subcutaneous injections of enoxacin, bis‐enoxacin, alendronate, or doxycycline were administered for 6 weeks after 6 weeks of polybacterial infection in rats. The serum levels of oxidative stress parameters and antioxidant enzymes, including glutathione peroxidase, superoxide dismutase, and catalase, were evaluated in each of the infected, treated, and sham‐infected rats. Results: Rats infected with the periodontal pathogens displayed a five‐fold increase in the oxidative stress index compared with controls as a result of increased levels of serum oxidants and decreases in total antioxidant activity. The overall decrease in antioxidant activity occurred despite increases in three important antioxidant enzymes, suggesting an imbalance between antioxidant macromolecules/small molecules production and antioxidant enzyme levels. Surprisingly, the bone‐targeted antiresorptives bis‐enoxacin and alendronate inhibited increases in oxidative stress caused by periodontitis. Bis‐enoxacin, which has both antiresorptive and antibiotic activities, was more effective than alendronate, which acts only as an antiresorptive. Conclusion: To the best of the authors’ knowledge, this is the first study to demonstrate that the increased oxidative stress induced by periodontal infection in rats can be ameliorated by bone‐targeted antiresorptives. 相似文献