全文获取类型
收费全文 | 2575篇 |
免费 | 119篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 69篇 |
妇产科学 | 53篇 |
基础医学 | 294篇 |
口腔科学 | 32篇 |
临床医学 | 268篇 |
内科学 | 482篇 |
皮肤病学 | 30篇 |
神经病学 | 117篇 |
特种医学 | 70篇 |
外国民族医学 | 3篇 |
外科学 | 507篇 |
综合类 | 69篇 |
一般理论 | 7篇 |
预防医学 | 126篇 |
眼科学 | 143篇 |
药学 | 225篇 |
中国医学 | 19篇 |
肿瘤学 | 149篇 |
出版年
2023年 | 27篇 |
2022年 | 102篇 |
2021年 | 112篇 |
2020年 | 62篇 |
2019年 | 104篇 |
2018年 | 111篇 |
2017年 | 71篇 |
2016年 | 79篇 |
2015年 | 88篇 |
2014年 | 136篇 |
2013年 | 143篇 |
2012年 | 208篇 |
2011年 | 228篇 |
2010年 | 133篇 |
2009年 | 95篇 |
2008年 | 147篇 |
2007年 | 158篇 |
2006年 | 123篇 |
2005年 | 123篇 |
2004年 | 106篇 |
2003年 | 86篇 |
2002年 | 77篇 |
2001年 | 23篇 |
2000年 | 29篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有2706条查询结果,搜索用时 15 毫秒
71.
Muhammad Badar Heinrich Lünsdorf Florian Evertz Muhammad Imran Rahim Birgit Glasmacher Hansjörg Hauser Peter P. Mueller 《Acta biomaterialia》2013,9(7):7580-7589
Magnesium alloys have been proposed as prospective degradable implant materials. To elucidate the complex interactions between the corroding implants and the tissue, magnesium implants were analyzed in a mouse model and the response was compared to that induced by Ti and by the resorbable polymer polyglactin, respectively. One month after implantation, distinct traces of corrosion were apparent but the magnesium implants were still intact, whereas resorbable polymeric wound suture implants were already fragmented. Analysis of magnesium implants 2 weeks after implantation by energy-dispersive X-ray spectroscopy indicated that magnesium, oxygen, calcium and phosphate were present at the implant surface. One month after implantation, the element composition of the outermost layer of the implant was indicative of tissue without detectable levels of magnesium, indicating a protective barrier function of this organic layer. In agreement with this notion, gene expression patterns in the surrounding tissue were highly similar for all implant materials investigated. However, high-resolution imaging using energy-filtered transmission electron microscopy revealed magnesium-containing microparticles in the tissue in the proximity of the implant. The release of such corrosion particles may contribute to the accumulation of calcium phosphate in the nearby tissue and to bone conductive activities of magnesium implants. 相似文献
72.
73.
74.
Permanent complete heart block (CHB) secondary to the loss of first septal perforator after percutaneous coronary intervention (PCI) of the left descending artery (LAD) is an extremely rare complication. We describe a case report where a patient underwent PCI of proximal LAD, complicated by loss of first septal perforator, septal infarction, and bifasicular block, which progressed to symptomatic delayed CHB. One week later, the patient required implantation of a permanent pacemaker following failure to wean off the transvenous temporary pacing maker. 相似文献
75.
76.
77.
78.
Muhammad Imran Din Rida Khalid Zaib Hussain Jawayria Najeeb Ahsan Sahrif Azeem Intisar Ejaz Ahmed 《RSC advances》2020,10(32):19041
Conversion of nitroaniline (NA), a highly toxic pollutant that has been released into aquatic systems due to unmanaged industrial development in recent years, into the less harmful or a useful counterpart is the need of the hour. Various methods for its conversion and removal have been explored. Owing to its nominal features of advanced effectiveness, the chemical reduction of 4-NA using various different nanocatalytic systems is one such approach that has attracted tremendous interest over the past few years. The academic literature has been confined to case studies involving silver (Ag) and gold (Au) nanoparticles, as these are the two most widely used materials for the synthesis of nanocatalytic assemblies. Focus has also been given to sodium borohydride (NaBH4), which is used as a reductant during the chemical reduction of NA. This systematic review summarizes the fundamentals associated with the catalytic degradation of 4-NA, and presents a comprehensive and critical study of the latest modifications used in the synthesis of these catalytic systems. In addition, the kinetics, mechanisms, thermodynamics, as well as the future directions required for understanding this model reaction, have been provided in this particular study.Schematic illustration of catalytic reduction of 4-NA in the presence of nanocatalysts and a reducing agent. 相似文献
79.
Imran Khan Haibo Zhang Wei Liu Liping Zhang Fang Peng Yuchan Chen Qingbo Zhang Guangtao Zhang Weimin Zhang Changsheng Zhang 《RSC advances》2020,10(35):20738
Extracts from Antarctic-derived Penicillium chrysogenum CCTCC M 2020019 showed potent antibacterial bioactivities. We report herein the isolation of chrysonin (1), a new compound containing a pair of enantiomers 6S- and 6R-chrysonin (1a and 1b) featuring an unprecedented eight-membered heterocycle fused with a benzene ring. Compound 2, a mixture consisting of a new zwitterionic compound chrysomamide (2a) and N-[2-trans-(4-hydroxyphenyl) ethenyl] formamide (2b) in a ratio around 1 : 2.8, was isolated together with seven known compounds 3–9. Chemical structures of all compounds were determined by comprehensive spectroscopic analyses. The isolated compounds were evaluated for antimicrobial, cytotoxic and alpha-glucosidase inhibition activities. Chrysonin (1) showed moderate alpha-glucosidase inhibitory activity. The dominant product xanthocillin X (4) displayed potent inhibition activities against Gram-negative pathogens Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa with MIC values at 0.125 μg mL−1. Xanthocillins X (4) and Y1 (5) also showed significant cytotoxicities against four cancer cell lines with IC50 values ranging from 0.26 to 5.04 μM. This study highlights that microorganisms from polar regions are emerging as a new resource for the discovery of natural products combating human pathogens.The unprecedented eight-membered heterocyclic chrysonin (1) was isolated from an Antarctic fungus that also produced xanthocillins 4 and 5 as potent inhibitors against Gram-negative pathogens. 相似文献
80.
M. Ikram R. Tabassum U. Qumar S. Ali A. Ul-Hamid A. Haider A. Raza M. Imran S. Ali 《RSC advances》2020,10(35):20559
Nanostructured materials incorporated with biological reducing agents have shown significant potential for use in bactericidal applications. Such materials have also demonstrated considerable efficacy to counter effects of chemical toxicity. In this study, nanostructured molybdenum disulfide (MoS2) was doped with various concentrations (2.5, 5, 7.5, 10 wt%) of zirconium (Zr) using a hydrothermal route in order to assess its antimicrobial and catalytic potential. Doped and control samples were characterized with various techniques. X-ray diffraction (XRD) analysis confirmed the presence of the hexagonal phase of MoS2 and identification of various functional groups and characteristic peaks (Mo bonding) was carried out using FTIR spectra. Micrographs obtained from FESEM and HR-TEM showed a sheet-like surface morphology, while agglomeration of nanosheets was observed upon doping with nanoparticles. To seek further clarity regarding the layered features of S–Mo–S planes, the defect densities and electronic band structure of pure MoS2 and doped MoS2 samples were investigated through Raman analysis. Optical properties of Zr-doped MoS2 nanosheets were assessed using a UV-vis spectrophotometer and the results indicated a red-shift, i.e., movement of peaks towards longer wavelengths, of the material. Dynamics of migration and recombination of excited electron–hole pairs were investigated using PL spectroscopy, which was also used to confirm the presence of exfoliated nanosheets. In addition, the synthetic dye degradation potential of pure and doped samples was investigated in the presence of a reducing agent (NaBH4). It was noted that doped MoS2 showed superior catalytic activity compared to undoped MoS2. The nanocatalyst synthesized in this study exhibited enhanced antibacterial activity against E. coli and S. aureus at high concentrations (0.5, 1.0 mg/50 μl). The present study suggests a cost-effective and environmentally friendly material that can be used to remove toxins such as synthetic dyes and tannery pollutants from industrial wastewater.Nanostructured materials incorporated with biological reducing agents have shown significant potential for use in bactericidal applications. 相似文献