全文获取类型
收费全文 | 42701篇 |
免费 | 3272篇 |
国内免费 | 126篇 |
专业分类
耳鼻咽喉 | 415篇 |
儿科学 | 1151篇 |
妇产科学 | 760篇 |
基础医学 | 6324篇 |
口腔科学 | 809篇 |
临床医学 | 4641篇 |
内科学 | 8751篇 |
皮肤病学 | 855篇 |
神经病学 | 4237篇 |
特种医学 | 1562篇 |
外国民族医学 | 11篇 |
外科学 | 5957篇 |
综合类 | 534篇 |
一般理论 | 36篇 |
预防医学 | 3632篇 |
眼科学 | 805篇 |
药学 | 2994篇 |
中国医学 | 94篇 |
肿瘤学 | 2531篇 |
出版年
2023年 | 322篇 |
2022年 | 535篇 |
2021年 | 1036篇 |
2020年 | 707篇 |
2019年 | 954篇 |
2018年 | 1150篇 |
2017年 | 907篇 |
2016年 | 1023篇 |
2015年 | 1082篇 |
2014年 | 1497篇 |
2013年 | 1861篇 |
2012年 | 2870篇 |
2011年 | 3026篇 |
2010年 | 1697篇 |
2009年 | 1415篇 |
2008年 | 2322篇 |
2007年 | 2533篇 |
2006年 | 2365篇 |
2005年 | 2157篇 |
2004年 | 2056篇 |
2003年 | 1741篇 |
2002年 | 1631篇 |
2001年 | 800篇 |
2000年 | 802篇 |
1999年 | 699篇 |
1998年 | 400篇 |
1997年 | 301篇 |
1996年 | 312篇 |
1995年 | 269篇 |
1994年 | 232篇 |
1993年 | 181篇 |
1992年 | 413篇 |
1991年 | 411篇 |
1990年 | 408篇 |
1989年 | 344篇 |
1988年 | 337篇 |
1987年 | 381篇 |
1986年 | 367篇 |
1985年 | 348篇 |
1984年 | 305篇 |
1983年 | 240篇 |
1982年 | 168篇 |
1979年 | 297篇 |
1978年 | 215篇 |
1977年 | 197篇 |
1976年 | 164篇 |
1975年 | 172篇 |
1974年 | 177篇 |
1973年 | 202篇 |
1971年 | 168篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
Objectives
Iatrogenic injury of the Profunda Femoris Artery (PFA) at time of hip fixation surgery can increase morbidity and mortality and prolong the hospital stay. This is an injury that tends to pass unnoticed as a cause of postoperative deterioration despite being frequently reported in the literature. Our study aims to describe the anatomy of the PFA in relation to the medial femoral cortex with specific emphasis on its orientation relative to the position of a sliding hip screw side plate construct. By doing so we are able to present clear guidance to orthopaedic surgeons on how to avoid iatrogenic PFA injury at the time of hip fracture fixation.Methods
Using Computed Tomography Angiographic (CTA) studies, the course of the PFA in relation to the medial femoral cortex was traced in 44 patients (28 males and 16 females) with mean age of 65.6 years. Coronal and axial CT sections were cross-linked to specify the position of the PFA at 1?cm intervals.Results
The course of the artery could be divided into three parts relative to a fixed reference point. Proximal and distal parts of the artery were in a safer position in comparison to the middle part of the artery that was found very close to the femoral cortex and along the coronal axis of the femur (mean angle 2.9° from the femoral coronal axis and 13.8?mm from the medial femoral cortex). Using the commercially available side plate constructs, this part of the artery corresponded to the distal part of the plate (third and fourth holes).Conclusion
Special attention needs to be practiced by the operating surgeon while drilling into the third and fourth holes of the side plate. 相似文献4.
Adilson Cunha Ferreira Edward Araujo Júnior Wellington P. Martins João Francisco Jordão Antônio Hélio Oliani Simon E. Meagher 《The journal of maternal-fetal & neonatal medicine》2015,28(14):1706-1710
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality. 相似文献
5.
Lara Feulner Hamed S. Najafabadi Simon Tanguay Janusz Rak Yasser Riazalhosseini 《Urologic oncology》2019,37(2):166-175
Background
Clear cell renal cell carcinoma (ccRCC) is known to occur across the adult lifetime traversing the spectrum of age-related organismal changes. Little is known as to how the aging process may affect the course of renal cell carcinoma (RCC) and the repertoire of genes involved.Methods
Using The Cancer Genome Atlas (n?=?436) and Cancer Genomics of the Kidney (n?=?89) datasets, we applied regression analysis to examine associations between patient age and gene expression profiles in ccRCC tumors and normal kidney tissues. Pathway enrichment analysis was performed to identify cellular process that is affected by aging in ccRCC. Moreover, connectivity mapping analysis was used to predict age-dependent response to drug treatments.Results
Our analysis revealed different age-dependent gene expression spectra in ccRCC and normal kidney tissues. These findings were significant and independently reproducible in both datasets examined. Age up-regulated genes, showing higher expression in older patients, were significantly enriched (false discovery rate <0.05) in normal tissues for pathways associated with immune response and extracellular matrix organization, whereas age up-regulated genes in tumors were enriched for metabolism and oxidation pathways. Strikingly, age down-regulated genes in normal cells were also enriched for metabolism and oxidation, while those in tumors were enriched for extracellular matrix organization. Further in silico analysis of potential drug targets predicted preferential efficacy of Phosphoinositide 3-kinase inhibitor or immunotherapy in association with age.Conclusion
We report on previously unrecognized associations between age and molecular underpinnings of RCC, including age-associated expression of genes implicated in RCC development or treatment. 相似文献6.
7.
TG Berger F Kiesewetter C Maczek N Bauer M Lueftl G Schuler M Simon Jr 《Journal of the European Academy of Dermatology and Venereology》2006,20(2):178-183
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis. 相似文献
8.
Frances J. Mather Richard M. Simon Gary M. Clark Daniel D. 《Statistics in medicine》1990,9(9):1118-1118
9.
Patients at Boston's Children's Hospital diagnosed as having cerebral palsy were filmed walking. These films were digitized and translated into measurements associated with leg motion. In this paper we use the gait measurements of 128 such patients to illustrate that the kth nearest neighbour clustering procedure results in a gait typology for patients with cerebral palsy. The procedure identifies four subpopulations from the sample data; the membership of a patient within this typology is mostly determined by the patient's motor control. The developed typology differs from the present diagnostic system which classifies a cerebral palsy patient as either quadriplegic, diaplegic or hemiplegic. 相似文献
10.
The spatial spread within fly photoreceptors of 2 forms of desensitization by bright light have been investigated: the natural process of light adaptation in normal Musca photoreceptors and a receptor-potential inactivation in the no-steady-state (nss) mutant of the sheep blowfly Lucilia. The suction-electrode method used for recording from vertebrate rods was applied to fly ommatidia. A single ommatidium in vitro was partially sucked into a recording pipette. Illumination of the portion of the ommatidium within the pipette resulted in a flow of current having a wave form similar to that of the receptor potential and polarity consistent with current flow into the illuminated region of the photoreceptors. Two 5-microns slits of light, positioned at right angles to the ommatidial axis, were employed to determine the spread of light adaptation or inactivation along the ommatidium. The intensity of a flash of light delivered to one (adapting) slit was adjusted until it produced a criterion fractional reduction in the response to the other (test) slit. The reciprocal of this intensity of the adapting slit was taken as a measure of the effectiveness of the slit in causing light adaptation or inactivation. The effectiveness of the slit in causing light adaptation in normal Musca ommatidia fell as the adapting and test slits were moved farther apart along the ommatidial axis, declining to half its maximal value at a distance of 13 +/- 2 microns. Similar measurements of the effectiveness of a slit in causing light-induced inactivation in the nss mutant of Lucilia also demonstrated localization, declining to half its maximal value at a distance between the slits of 9 +/- 1 microns. Neither light adaptation nor inactivation by the nss mutation, therefore, appear to be mediated by voltage or by a highly diffusible agent. The results are consistent with the idea that inactivation by the nss mutation replaces adaptation in the mutant photoreceptors. 相似文献