全文获取类型
收费全文 | 6231篇 |
免费 | 389篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 61篇 |
儿科学 | 159篇 |
妇产科学 | 94篇 |
基础医学 | 1076篇 |
口腔科学 | 348篇 |
临床医学 | 469篇 |
内科学 | 1433篇 |
皮肤病学 | 189篇 |
神经病学 | 548篇 |
特种医学 | 116篇 |
外科学 | 560篇 |
综合类 | 46篇 |
一般理论 | 2篇 |
预防医学 | 519篇 |
眼科学 | 112篇 |
药学 | 467篇 |
中国医学 | 49篇 |
肿瘤学 | 428篇 |
出版年
2024年 | 8篇 |
2023年 | 114篇 |
2022年 | 225篇 |
2021年 | 354篇 |
2020年 | 204篇 |
2019年 | 282篇 |
2018年 | 272篇 |
2017年 | 188篇 |
2016年 | 260篇 |
2015年 | 250篇 |
2014年 | 287篇 |
2013年 | 358篇 |
2012年 | 548篇 |
2011年 | 577篇 |
2010年 | 281篇 |
2009年 | 213篇 |
2008年 | 370篇 |
2007年 | 343篇 |
2006年 | 307篇 |
2005年 | 315篇 |
2004年 | 251篇 |
2003年 | 243篇 |
2002年 | 191篇 |
2001年 | 22篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 48篇 |
1997年 | 25篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有6676条查询结果,搜索用时 15 毫秒
51.
52.
Medical records of 51 patients with a diagnosis of pars planitis (97 eyes) were reviewed. Based upon the severity of vitreous inflammation, in 34 eyes (35) the condition was classified as mild, in 38 (39) as moderate, and in 25 eyes (26) as severe. Vascular sheathing was present in 51 eyes (53), snowballs in 42 (43), snowbanks in 29 (30), cataract in 19 (20), cystoid macular edema in 26 (27), retinal detachment in 4 (4) and glaucoma in 3 (3) eyes. Treatment consisted of prednisone and periocular injections of deposteroids or immunosuppressive agents; 13 patients required surgery for retinal repair, glaucoma, vitreous opacities or cataract. After treatment the visual acuity improved in 58 of the eyes, did not change in 33, and worsened in 9. 相似文献
53.
Carla A. Losantos-Saavedra Gabriela A. Bustillos-García Jorge M. Catrip-Torres Santiago Nava 《Archivos de cardiología de México》2022,92(3):358
Catheter ablation is useful for reducing drug refractory ventricular tachycardia (VT) episodes and can be life-saving when VT is incessant or arrhythmic storm. Left ventricular hemodynamic support may be required in patients with VT and hemodynamic instability. Extracorporeal membrane oxygenation (ECMO) support is an alternative to achieve ventricular tachycardia mapping and ablation over long periods of time. We present a case of successful catheter ablation of substrate in a patient with ischemic heart disease and ventricular tachycardia with hemodynamic instability performed using venous- arterial ECMO support. There were not episodes of ventricular tachycardia after 2 years of follow-up. 相似文献
54.
Karla ech Barabaszov Ale Slíva Gabriela Kratoov Sylva Holeov Anastasia Volodarskaja Tugrul Cetinkaya Silvie Broov Libor Kozubek Grayna Simha Martynkov 《Materials》2022,15(15)
Today, Ni-Cr steel is used for advanced applications in the high-temperature and electrical industries, medical equipment, food industry, agriculture and is applied in food and beverage packaging and kitchenware, automotive or mesh. A study of input steel powder from various stages of the recycling process intended for 3D printing was conducted. In addition to the precise evaluation of the morphology, particle size and composition of the powders used for laser 3D printing, special testing and evaluation of the heat-treated powders were carried out. Heat treatment up to 950 °C in an air atmosphere revealed the properties of powders that can appear during laser sintering. The powders in the oxidizing atmosphere change the phase composition and the original FeNiCr stainless steel changes to a two-phase system of Fe3Ni and Cr2O3, as evaluated by X-ray diffraction analysis. Observation of the morphology showed the separation of the oxidic phase in the sense of a brittle shell. The inner part of the powder particle is a porous compact core. The particle size is generally reduced due to the peeling of the oxide shell. This effect can be critical to 3D printing processing, causing defects on the printed parts, as well as reducing the usability of the precursor powder and can also change the properties of the printed part. 相似文献
55.
Camelia Ungureanu Gratiela Teodora Tihan Roxana Gabriela Zgrian Irina Fierascu Anda Maria Baroi Silviu Rileanu Radu Claudiu Fierscu 《Materials》2022,15(15)
Nowadays, special importance is given to quality control and food safety. Food quality currently creates significant problems for the industry and implicitly for consumers and society. The effects materialize in economic losses, alterations of the quality and organoleptic properties of the commercial products, and, last but not least, they constitute risk factors for the consumer’s health. In this context, the development of analytical systems for the rapid determination of the sanitary quality of food products by detecting possible pathogenic microorganisms (such as Escherichia coli or Salmonella due to the important digestive disorders that they can cause in many consumers) is of major importance. Using efficient and environmentally friendly detection systems for identification of various pathogens that modify food matrices and turn them into food waste faster will also improve agri-food quality throughout the food chain. This paper reviews the use of metal nanoparticles used to obtain bio nanosensors for the purpose mentioned above. Metallic nanoparticles (Au, Ag, etc.) and their oxides can be synthesized by several methods, such as chemical, physical, physico-chemical, and biological, each bringing advantages and disadvantages in their use for developing nanosensors. In the “green chemistry” approach, a particular importance is given to the metal nanoparticles obtained by phytosynthesis. This method can lead to the development of good quality nanoparticles, at the same time being able to use secondary metabolites from vegetal wastes, as such providing a circular economy character. Considering these aspects, the use of phytosynthesized nanoparticles in other biosensing applications is also presented as a glimpse of their potential, which should be further explored. 相似文献
56.
Adina Frum Carmen Maximiliana Dobrea Luca Liviu Rus Lidia-Ioana Virchea Claudiu Morgovan Adriana Aurelia Chis Anca Maria Arseniu Anca Butuca Felicia Gabriela Gligor Laura Gratiela Vicas Ovidiu Tita Cecilia Georgescu 《Nutrients》2022,14(15)
Grape pomace and berries represent natural sources of phytochemicals that can increase the quality of life of consumers by contributing to the prevention of chronic diseases; thus, the development of a dietary supplement was necessary. The raw material (r.m.) used for the development of the dietary supplement consisted of dried and powdered bilberries (Vaccinium myrtillus L.), red currants (Ribes rubrum L.), and red fermented pomaces (Vitis vinifera L.) from Feteasca Neagra and Cabernet Sauvignon cultivars. The particle size distribution, powder flow, total phenolic content (TPC), HPLC-DAD phenolic profile assessment, and radical scavenging assay (RSA) were employed for the analysis of the raw material. After encapsulation, the average mass and uniformity of mass, the disintegration, and the uniformity of content for the obtained capsules were performed to obtain a high-quality dietary supplement. All the assays performed complied to the compendial requirements and the TPC was determined at 9.07 ± 0.25 mg gallic acid equivalents/g r.m. and RSA at 48.32 ± 0.74%. The highest quantities of phenolic compounds determined were 333.7 ± 0.50 µg/g r.m. for chlorogenic acid, followed by rutin, ferulic acid, and (+)-catechin with 198.9 ± 1.60 µg/g r.m., 179.8 ± 0.90 µg/g r.m. and 118.7 ± 0.75 µg/g r.m., respectively. The results of this study can be used for the manufacturing and assessing of pilot scale-up capsule batches and thinking of quality assurance, we recommend that the industrial batch extracts should be standardized in polyphenols, and the manufacturing process should be validated. 相似文献
57.
58.
Gabriela Guizzo Dri Phoebe R. Spencer Raimundo da Costa Katherine A. Sanders Debra S. Judge 《Maternal & child nutrition》2022,18(3)
Both child growth and dietary diversity are poor in rural Timor‐Leste. The rainy season is associated with food scarcity, yet the association between seasonal scarcity, food diversity, and child growth is underdocumented. This study assesses the relationship between household dietary diversity and children''s standardized growth across the 2018 food‐scarce (April–May; post‐rainy period) and post‐harvest (October) seasons in the agricultural community of Natarbora, on the south‐coastal plains of Timor‐Leste. We conducted household interviews and collected anthropometric data across 98 and 93 households in the post‐rainy and post‐harvest periods, respectively. Consumed household foods were obtained via 24‐h diet recalls and were subsequently categorized into a nine‐food‐group dietary diversity score (DDS; number of different food groups consumed). The DDS was related to children''s standardized short‐term growth (z‐weight, z‐body mass index [BMI] and percent change in weight over the harvest season) via linear mixed models. Across seasons, DDS increased from 3.9 (standard deviation [SD] = 1.0) to 4.3 (SD = 1.4; p < 0.05). In the post‐rainy season, children in high DDS households had higher z‐weight than those in low DDS households and higher z‐BMI than children in medium and low DDS households. In the post‐harvest period, household DDS did not predict children''s z‐weight but predicted z‐BMI. Consumption of protein‐rich foods, particularly animal‐source foods and legumes, in low‐ and medium‐DDS households may be associated with improved child growth. While consuming more animal‐source foods in the post‐rainy season would be ideal, promoting the consumption of locally grown legumes, such as beans and pulses, may facilitate better nutritional outcomes for more children in rural Timor‐Leste. 相似文献
59.
Laura Madalina Cursaru Miruna Iota Roxana Mioara Piticescu Daniela Tarnita Sorin Vasile Savu Ionel Dnu Savu Gabriela Dumitrescu Diana Popescu Radu-Gabriel Hertzog Mihaela Calin 《Materials》2022,15(15)
The aim of this work is to study the physical-chemical, mechanical, and biocompatible properties of hydroxyapatite obtained by hydrothermal synthesis, at relatively low temperatures and high pressures, starting from natural sources (Rapana whelk shells), knowing that these properties influence the behavior of nanostructured materials in cells or tissues. Thus, hydroxyapatite nanopowders were characterized by chemical analysis, Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In vitro studies on osteoblast cell lines (cytotoxicity and cell proliferation), as well as preliminary mechanical tests, have been performed. The results showed that the obtained powders have a crystallite size below 50 nm and particle size less than 100 nm, demonstrating that hydrothermal synthesis led to hydroxyapatite nanocrystalline powders, with a Ca:P ratio close to the stoichiometric ratio and a controlled morphology (spherical particle aggregates). The tensile strength of HAp samples sintered at 1100 °C/90 min varies between 37.6–39.1 N/mm2. HAp samples sintered at 1300 °C/120 min provide better results for the investigated mechanical properties. The coefficient of friction has an appropriate value for biomechanical applications. The results of cell viability showed that the cytotoxic effect is low for all tested samples. Better cell proliferation is observed for osteoblasts grown on square samples. 相似文献
60.
Georgiana-Emmanuela Gilca-Blanariu Anca Trifan Manuela Ciocoiu Iolanda Valentina Popa Alexandru Burlacu Gheorghe G. Balan Andrei Vasile Olteanu Gabriela Stefanescu 《Nutrients》2022,14(9)
The altered magnesium status in inflammatory bowel disease (IBD) patients may have a significant clinical imprint considering its role in cell signaling and genomic stability, as well as its involvement in IBD patients’ fatigue. Our study pioneers the investigation of magnesium hair concentration patterns in an adult population of IBD patients. The hair magnesium concentration in IBD patients is compared to healthy controls in order to identify correlations between the magnesium status and relevant parameters related to disease activity, psychological status, and sleep quality. We report a significantly lower hair magnesium concentration within the IBD group compared to healthy controls (95%CI: 0.006–0.062; p = 0.017) and lower levels in CD compared to UC (95%CI: −0.061–−0.002; p = 0.038). We identified a borderline statistical significance between the hair magnesium concentration and UC disease activity (95%CI; −0.679–0.008; p = 0.055) and a significantly lower magnesium concentration in patients who reported increased sleep latency (95%CI −0.65–−0.102; p = 0.011) or decreased sleep duration (95%CI −0.613–−0.041; p = 0.028). Our results advance several hypotheses with substantial clinical impact to be confirmed in future studies. Magnesium levels appear to be modified in IBD patients, which suggests it either plays a primary role in disease pathophysiology or a is result of the disease’s evolution. Magnesium could be used in predictive models for clinical/subclinical disease activity. Moreover, magnesium supplementation may improve IBD evolution and sleep quality for patients with a deficit of this mineral. However, confirmatory evidence-based studies are needed to generate specific dosing, time of supplementation, and optimum monitoring of magnesium status in IBD patients. 相似文献