全文获取类型
收费全文 | 2853篇 |
免费 | 189篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 92篇 |
妇产科学 | 66篇 |
基础医学 | 364篇 |
口腔科学 | 56篇 |
临床医学 | 263篇 |
内科学 | 715篇 |
皮肤病学 | 85篇 |
神经病学 | 229篇 |
特种医学 | 138篇 |
外科学 | 324篇 |
综合类 | 39篇 |
一般理论 | 1篇 |
预防医学 | 234篇 |
眼科学 | 67篇 |
药学 | 189篇 |
中国医学 | 14篇 |
肿瘤学 | 154篇 |
出版年
2023年 | 20篇 |
2022年 | 33篇 |
2021年 | 100篇 |
2020年 | 46篇 |
2019年 | 77篇 |
2018年 | 102篇 |
2017年 | 64篇 |
2016年 | 68篇 |
2015年 | 88篇 |
2014年 | 108篇 |
2013年 | 118篇 |
2012年 | 151篇 |
2011年 | 166篇 |
2010年 | 92篇 |
2009年 | 99篇 |
2008年 | 152篇 |
2007年 | 174篇 |
2006年 | 141篇 |
2005年 | 136篇 |
2004年 | 129篇 |
2003年 | 106篇 |
2002年 | 91篇 |
2001年 | 79篇 |
2000年 | 79篇 |
1999年 | 79篇 |
1998年 | 28篇 |
1997年 | 36篇 |
1996年 | 17篇 |
1995年 | 28篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 37篇 |
1991年 | 32篇 |
1990年 | 40篇 |
1989年 | 44篇 |
1988年 | 33篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1971年 | 9篇 |
排序方式: 共有3081条查询结果,搜索用时 62 毫秒
31.
Marysol Luna Jason D Guss Laura S Vasquez-Bolanos Macy Castaneda Manuela Vargas Rojas Jasmin M Strong Denise A Alabi Sophie D Dornevil Jacob C Nixon Erik A Taylor Eve Donnelly Xueyan Fu M Kyla Shea Sarah L Booth Rodrigo Bicalho Christopher J Hernandez 《Journal of bone and mineral research》2021,36(9):1823-1834
Modifications to the constituents of the gut microbiome influence bone density and tissue-level strength, but the specific microbial components that influence tissue-level strength in bone are not known. Here, we selectively modify constituents of the gut microbiota using narrow-spectrum antibiotics to identify components of the microbiome associated with changes in bone mechanical and material properties. Male C57BL/6J mice (4 weeks) were divided into seven groups (n = 7–10/group) and had taxa within the gut microbiome removed through dosing with: (i) ampicillin; (ii) neomycin; (iii) vancomycin; (iv) metronidazole; (v) a cocktail of all four antibiotics together (with zero-calorie sweetener to ensure intake); (vi) zero-calorie sweetener only; or (vii) no additive (untreated) for 12 weeks. Individual antibiotics remove only some taxa from the gut, while the cocktail of all four removes almost all microbes. After accounting for differences in geometry, whole bone strength was reduced in animals with gut microbiome modified by neomycin (−28%, p = 0.002) and was increased in the group in which the gut microbiome was altered by sweetener alone (+39%, p < 0.001). Analysis of the fecal microbiota detected seven lower-ranked taxa differentially abundant in animals with impaired tissue-level strength and 14 differentially abundant taxa associated with increased tissue-level strength. Histological and serum markers of bone turnover and trabecular bone volume per tissue volume (BV/TV) did not differ among groups. These findings demonstrate that modifications to the taxonomic components of the gut microbiome have the potential to decrease or increase tissue-level strength of bone independent of bone quantity and without noticeable changes in bone turnover. © 2021 American Society for Bone and Mineral Research (ASBMR). 相似文献
32.
33.
Albright Christopher A. Kimball Devon Brady John P. Luna Issabella Brown Tiffany Calzo Jerel P. Pennesi Jamie-Lee Blashill Aaron J. 《Archives of sexual behavior》2022,51(5):2523-2533
Archives of Sexual Behavior - Sexual minority men (SMM) remain disproportionately burdened by sexually transmitted infections. Although gay community involvement has been theorized to be protective... 相似文献
34.
Carleigh B. Krubiner Ruth R. Faden Ruth A. Karron Margaret O. Little Anne D. Lyerly Jon S. Abramson Richard H. Beigi Alejandro R. Cravioto Anna P. Durbin Bruce G. Gellin Swati B. Gupta David C. Kaslow Sonali Kochhar Florencia Luna Carla Saenz Jeanne S. Sheffield Paulina O. Tindana 《Vaccine》2021,39(1):85-120
Zika virus, influenza, and Ebola have called attention to the ways in which infectious disease outbreaks can severely – and at times uniquely – affect the health interests of pregnant women and their offspring. These examples also highlight the critical need to proactively consider pregnant women and their offspring in vaccine research and response efforts to combat emerging and re-emerging infectious diseases. Historically, pregnant women and their offspring have been largely excluded from research agendas and investment strategies for vaccines against epidemic threats, which in turn can lead to exclusion from future vaccine campaigns amidst outbreaks. This state of affairs is profoundly unjust to pregnant women and their offspring, and deeply problematic from the standpoint of public health. To ensure that the needs of pregnant women and their offspring are fairly addressed, new approaches to public health preparedness, vaccine research and development, and vaccine delivery are required. This Guidance offers 22 concrete recommendations that provide a roadmap for the ethically responsible, socially just, and respectful inclusion of the interests of pregnant women in the development and deployment of vaccines against emerging pathogens. The Guidance was developed by the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) Working Group – a multidisciplinary, international team of 17 experts specializing in bioethics, maternal immunization, maternal-fetal medicine, obstetrics, pediatrics, philosophy, public health, and vaccine research and policy – in consultation with a variety of external experts and stakeholders. 相似文献
35.
p53 is the most frequently altered suppressor gene in human cancers. The genotypic and corresponding phenotypic abnormalities of this gene in head and neck squamous cell carcinoma (HNSCC) remain undefined. We analyzed the loss of heterozygosity (LOH) by restriction fragment length polymorphism (RFLP) at three polymorphic loci in the p53 gene and performed immunohistochemistry (MC) for its protein on paraffin-embedded tumor tissue from 20 previously sequenced tumor specimens. LOH was noted at one or more of the three polymorphic sites within the p53 gene in 12 (67%) of the 18 informative samples. Concordance between LOH and mutations was observed in 14 (78%) cases. Twelve (60%) tumors with point mutations were immunohistochemically reactive to p53 antibody and two (10%) lacked both genetic and immunohistochemical alterations. In six tumors (30%) contradictory results between immunohistochemistry and molecular analysis were observed. Our data indicate that: (i) simultaneous deletion and mutation of both p53 alleles was observed in the majority of head and neck squamous carcinomas and implicate this gene in the oncogenesis of these neoplasms, (ii) p53 immunohistochemical analysis may not fully account for the different molecular alterations of this gene, and (iii) no correlation between p53 abnormalities and clinicopathologic or DNA content characteristics of HNSCC was found. 相似文献
36.
37.
Bilateral macular hemorrhage after laser in situ keratomileusis 总被引:2,自引:0,他引:2
José Domingo Luna Victor Eduardo Reviglio Claudio Patricio Juárez 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1999,237(7):611-613
· Background: This is the first report of a bilateral submacular hemorrhage after LASIK surgery in an extreme myo pic patient.
A 31-year-old man underwent bilateral surgery for correction of –16.75+0.75×70° and –16.50+0.50×55°. · Methods: Case report. ·
Results: One day after surgery the patient’s uncorrected visual acuity was in the 20/50 range OU and by 17 days after surgery
his visual acuity had declined to 20/200 range. Fundus examination showed multifocal subretinal macular and posterior pole
hemorrhages. Fluorescein angiography showed some macular lesions compatible with lacquer cracks. · Conclusions: Preoperative
and postoperative fundus examination is important to detect this phenomenon. Patients should be informed of this rare complication.
Received: 2 June 1998 Revised version received: 16 November 1998 Accepted: 17 November 1998 相似文献
38.
David J. Stewart Robert S. Benjamin Mario Luna Lynn Feun Richard Caprioli William Seifert Ti Li Loo 《Cancer chemotherapy and pharmacology》1982,10(1):51-54
Summary Using X-ray fluorescence spectrometry, platinum concentrations were determined in autopsy tissue samples from 12 patients who had received cis-diamminedichloroplatinum (DDP) 20–120 mg/m2 up to 6 months antemortem. Tissue platinum concentrations were highest in liver (0.5–3.7 g/g wet weight), prostate (1.6–3.6 g/g), and kidney (0.4–2.9 g/g), somewhat lower in bladder, muscle, testicle, pancreas, and spleen, and lowest in bowel, adrenal, heart, lung, cerebrum, and cerebellum, Platinum concentrations in tumors were generally somewhat lower than the concentration in the organ in which the tumor was located, with the exception of intracerebral tumors. Different metastatic sites in the same patient had substantially different platinum concentrations and hepatic metasutases had the highest concentrations. Intra-arterial administration of drug may augment tissue concentrations of platinum. In a patient undergoing therapeutic abortion 4 days after treatment, the platinum concentration was 0.5 g/g in the placenta and 0.3 g/g in the fetus. The data suggest that for in vitro sensitivity testing, DDP concentrations of 7 g/ml should be used. 相似文献
39.
Reproducibility of patellofemoral CT scan measurements 总被引:3,自引:0,他引:3
Delgado-Martínez AD Rodríguez-Merchán EC Ballesteros R Luna JD 《International orthopaedics》2000,24(1):5-8
At least seven parameters have been described for the measurement of patellofemoral malalignment on CT scanning; three of which measure lateral patellar tilt, two lateral patellar shift and two femoral trochlear dysplasia. We studied 22 knees in 18 patients complaining of patellofemoral pain in order to investigate the reproducibility of these methods. CT scans of the patellofemoral joint were performed in each knee at 0 degrees and 20 degrees of flexion. The seven parameters were recorded from each scan by three independent observers in a blind study. The reproducibility was studied by means of the intraclass correlation coefficient (ICC). Parameters measuring lateral patellar tilt showed excellent reliability (ICC>75%). The measurements of lateral patellar shift and femoral trochlear dysplasia showed a fair or poor correlation (ICC<75%). We suggest that parameters for measuring lateral patellar tilt only should be used from CT scanning when planning treatment for patello-femoral malalignment. 相似文献
40.
Morphological changes in the Buffalo Green Monkey (BGM) cell line after exposure to a subcytotoxic dose (0.062 mM, equivalent to EC(10)-effective concentration 10%) of cadmium chloride have been evaluated. Cells were exposed for 24 h and the effects observed at the ultrastructural level by transmission and scanning microscopy. Using transmission electron microscopy, the most notable findings in treated cells were the presence of intranuclear inclusion bodies and thin intracytoplasmic granules associated to myelin figures and the presence of apoptotic bodies. Other morphological alterations included cell vacuolisation and a reduced cytoplasm volume, condensation of the mitochondria and a decreased number of cytoplasmic organelles, except lysosomes and autophagic vacuoles, which increased in number. Scanning electron microscopy pointed to a cell with a disrupted perinuclear region and a decrease in the number of surface microvilli. We conclude that the BGM cell line may be considered an useful tool for toxicological studies involving cadmium. 相似文献