全文获取类型
收费全文 | 3217篇 |
免费 | 209篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 116篇 |
妇产科学 | 147篇 |
基础医学 | 320篇 |
口腔科学 | 130篇 |
临床医学 | 271篇 |
内科学 | 537篇 |
皮肤病学 | 84篇 |
神经病学 | 147篇 |
特种医学 | 117篇 |
外国民族医学 | 2篇 |
外科学 | 597篇 |
综合类 | 74篇 |
一般理论 | 3篇 |
预防医学 | 230篇 |
眼科学 | 95篇 |
药学 | 336篇 |
中国医学 | 21篇 |
肿瘤学 | 196篇 |
出版年
2023年 | 36篇 |
2022年 | 108篇 |
2021年 | 172篇 |
2020年 | 121篇 |
2019年 | 163篇 |
2018年 | 186篇 |
2017年 | 105篇 |
2016年 | 131篇 |
2015年 | 119篇 |
2014年 | 138篇 |
2013年 | 220篇 |
2012年 | 257篇 |
2011年 | 296篇 |
2010年 | 158篇 |
2009年 | 104篇 |
2008年 | 176篇 |
2007年 | 140篇 |
2006年 | 139篇 |
2005年 | 103篇 |
2004年 | 115篇 |
2003年 | 81篇 |
2002年 | 68篇 |
2001年 | 33篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 22篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 11篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 9篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有3463条查询结果,搜索用时 15 毫秒
71.
Arezou Masteri Farahani Fariba Maleki Nourollah Sadeghzadeh Saeid Abediankenari Seyed Mohammad Abedi Mostafa Erfani 《Chemical biology & drug design》2020,96(2):850-860
Prostate cancer is a serious threat to men's health, so it is necessary to develop the techniques for early detection of this malignancy. Radiolabeled peptides are the useful tools for diagnosis of prostate cancer. In this research, we designed a new HYNIC‐conjugated GnRH analogue and labeled it by 99mTc with tricine/EDDA as coligands. We used aminohexanoic acid (Ahx) as a hydrocarbon linker to generate 99mTc‐(tricine/EDDA)‐HYNIC‐Ahx‐[DLys6]GnRH. The radiopeptide exhibited high radiochemical purity and stability in solution and serum. Two human prostate cancer cell lines LN‐CaP and DU‐145 were used for cellular experiments. The binding specificity and affinity of radiopeptide for LN‐CaP were superior to DU‐145 cells. The Kd values for LN‐CaP and DU‐145 cells were 41.91 ± 7.03 nM and 55.96 ± 10.56 nM, respectively. High kidney uptake proved that the main excretion route of radiopeptide was through the urinary system. The tumor/muscle ratio of 99mTc‐HYNIC‐Ahx‐[DLys6]GnRH was 4.14 at 1 hr p.i. that decreased to 2.41 at 4 hr p.i. in LN‐CaP tumor‐xenografted nude mice. The blocking experiment revealed that the tumor uptake was receptor‐mediated. The lesion was visualized clearly using 99mTc‐[DLys6]GnRH at 1 hr p.i. Accordingly, this research highlights the capability of 99mTc‐(tricine/EDDA)‐HYNIC‐Ahx‐[DLys6]GnRH peptide as a promising agent for GnRHR‐expressing tumor imaging. 相似文献
72.
Samar Samir Youssef Asmaa Mostafa Abd El-Aal Amr Saad Moataza Hassan Omran Taher El Zanaty Sameh Mohamed Seif 《Disease markers》2013,35(5):431-437
Introduction. Hepatitis C virus (HCV) infection affects almost 3% of the world''s population with the highest prevalence in Egypt (15%). The standard therapy; pegylated interferon (PEG-IFN) and ribavirin, is effective in only 60% of Egyptian patients; moreover it is costly, prolonged, and has severe side effects, so prediction of response is essential to reduce burden of unfavorable treatment. Several viral and host factors have been proved to affect response to the treatment PEG-IFN and ribavirin; the strongest of them is polymorphisms near IL28B; nonetheless, nonresponse in patients with favorable IL28B is still unexplained, which implies the importance of studying other immunological factors that may correlate with response. Interleukin 12 (IL-12) is one of the most important proinflammatory cytokine presented with the initiation of immune response, determining Th1 and Th2 differentiation. A functional single nucleotide polymorphism (A/C) at the 3′ untranslated region (3′UTR) at position 1188 (NCBI SNP database no 3212227) was reported to be associated with responding more efficiently to antiviral combination therapy in HCV genotype 1 infected patients. The present study aims to evaluate association between this polymorphism with fibrosis stages, necroinflammation activity, response to the combined therapy, and gender in Egyptian HCV genotype 4. Material and Methods. A total of 133 Egyptian chronic HCV (CHCV) patients were treated with IFN/RBV and were followed up. IL12B 1188 A/C genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PRC-RFLP) analysis. Results. A nonsignificant trend for higher sustained virological response (SVR) was observed in patients homozygote for IL12B 1188 A/C SNP CC genotype (69% SVR versus 30.8% NR) only but not in AC and AA genotypes. No association was detected between IL12B 1188 A/C polymorphism and less severe fibrosis or less liver activity. By stratification of response according to gender genotype, a significant difference in response between males and females was seen among AA genotype carriers only due to high number of non responder females. Conclusion. IL12B CC genotype appears to have some influence on SVR achievement but not on severe fibrosis and severe necroinflamation activity. Females carrying A/A genotype of IL12B 1188 A/C SNP achieve less SVR than those carrying AC and CC genotypes. 相似文献
73.
Mostafa Jafari Thanh N. Nguyen Santiago Ortega-Gutierrez Muhammad Shazam Hussain Ameer E. Hassan Asad Ikram Javed Khader Eliyas Gustavo J. Rodriguez Afshin A. Divani 《Journal of stroke and cerebrovascular diseases》2021,30(3):105556
Objectives/BackgroundMedical therapy is the first line of treatment for intracranial atherosclerotic disease (ICAD). Percutaneous transluminal angioplasty and stenting (PTAS) are mainly considered for those patients with severe stenosis and recurrent events despite aggressive medical therapy. In this review, we discuss the application of PTAS as a treatment option for ICAD and its future prospect.Materials and MethodsWe did the literature review of the key articles and guidelines to elaborate on the role of PTAS in the management of ICAD based on the current data and expert opinion. We searched PubMed, Google Scholar, and Scopus up to August 2020, and included articles published only in the English language.ResultsSince the publication of the results from SAMMPRIS and VISSIT trials, stenting is no longer recommended for secondary stroke prevention in patients with symptomatic ICAD. However, recent clinical studies on intracranial stenting for a subgroup of ICAD patients have shown promising results, likely due to better patient selection and continued advancement of endovascular techniques.ConclusionThere exists a lack of consensus regarding the best endovascular treatment approach (e.g., angioplasty alone or balloon mounted stent vs. self-expanding stent with or without prior angioplasty) or management of in-stent restenosis. Another area of clinical controversy relates to the ideal use and duration of antiplatelet therapy. 相似文献
74.
Moamen M. Sarhan Mohamed M. Khamis Ahlam M. El-Sharkawy 《The Journal of prosthetic dentistry》2021,125(4):620-627
Statement of problemThe accuracy of partially guided implant placement protocols in comparison with fully guided protocols is still unclear. C-shaped guide holes have become popular; however, their effect on drilling and implant position accuracy has not been thoroughly investigated.PurposeThe purpose of this split-mouth clinical study was to evaluate the accuracy of implant placement by using fully guided versus partially guided surgical guides with cylindrical versus C-shaped guiding holes.Material and methodsAdopting 80% power of the study in calculating sample size, a total of 48 implants were placed in the mandibular interforaminal area of 12 edentulous participants, who were randomly divided into 2 groups: a fully guided group, comprising 24 implants placed on 1 side by using a fully guided protocol and a partially guided group, comprising 24 implants placed on the other side in a partially guided protocol. Each group was further subdivided into 2 subgroups: cylindrical, including 12 implants placed through cylindrical guide holes, and C-shaped (12 implants) placed through C-shaped guiding holes. Postoperative cone beam computed tomography scans were made, and based on image fusion, the total deviations between the virtually preplanned and actual implant positions were determined and compared between both groups and subgroups. The linear horizontal deviation of the implant hexagon and apex, together with apical depth deviation and angular deviations between the position of the actually placed and virtually planned implants, were analyzed in 3 dimensions. The Kolmogorov-Smirnov test of normality was used. Comparisons were carried out by using the Kruskal-Wallis test. Post hoc pair-wise comparisons when the Kruskal-Wallis test was significant were carried out by using the Dunn-Sidak test (α=.05).ResultsNo statistically significant differences were found in coronal linear deviation (P>.05), apical linear deviation (P>.05), apical depth deviation (P=.086), or angular deviation (P=.247), between the fully guided protocol and the partially guided protocol.ConclusionsThe accuracy of partially guided implant placement was clinically comparable with that of fully guided placement whether the guiding holes were cylindrical or C-shaped. 相似文献
75.
Pierre Lahoud Mostafa EzEldeen Thomas Beznik Holger Willems André Leite Adriaan Van Gerven Reinhilde Jacobs 《Journal of endodontics》2021,47(5):827-835
IntroductionTooth segmentation on cone-beam computed tomographic (CBCT) imaging is a labor-intensive task considering the limited contrast resolution and potential disturbance by various artifacts. Fully automated tooth segmentation cannot be achieved by merely relying on CBCT intensity variations. This study aimed to develop and validate an artificial intelligence (AI)-driven tool for automated tooth segmentation on CBCT imaging.MethodsA total of 433 Digital Imaging and Communications in Medicine images of single- and double-rooted teeth randomly selected from 314 anonymized CBCT scans were imported and manually segmented. An AI-driven tooth segmentation algorithm based on a feature pyramid network was developed to automatically detect and segment teeth, replacing manual user contour placement. The AI-driven tool was evaluated based on volume comparison, intersection over union, the Dice score coefficient, morphologic surface deviation, and total segmentation time.ResultsOverall, AI-driven and clinical reference segmentations resulted in very similar segmentation volumes. The mean intersection over union for full-tooth segmentation was 0.87 (±0.03) and 0.88 (±0.03) for semiautomated (SA) (clinical reference) versus fully automated AI-driven (F-AI) and refined AI-driven (R-AI) tooth segmentation, respectively. R-AI and F-AI segmentation showed an average median surface deviation from SA segmentation of 9.96 μm (±59.33 μm) and 7.85 μm (±69.55 μm), respectively. SA segmentations of single- and double-rooted teeth had a mean total time of 6.6 minutes (±76.15 seconds), F-AI segmentation of 0.5 minutes (±8.64 seconds, 12 times faster), and R-AI segmentation of 1.2 minutes (±33.02 seconds, 6 times faster).ConclusionsThis study showed a unique fast and accurate approach for AI-driven automated tooth segmentation on CBCT imaging. These results may open doors for AI-driven applications in surgical and treatment planning in oral health care. 相似文献
76.
Marwa M. Sobeih M. F. El-Shahat A. Osman M. A. Zaid Mostafa Y. Nassar 《RSC advances》2020,10(43):25567
We herein have developed a mild approach for the fabrication of glauconite clay (G)-modified chitosan (CS) nanocomposites by the combination of a simple blending and crosslinking method. The chitosan was modified with ethylenediaminetetraacetic acid (EDTA), glutaraldehyde (GL), sodium dodecyl sulfate (SDS), and cetyltrimethyl ammonium bromide (CTAB). The as-prepared composites were identified using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), nitrogen physical adsorption (BET), atomic absorption spectrophotometry (AA), and thermal gravimetric analysis (TGA). The adsorption activities of the as-prepared materials were assessed for the removal of fluoride ions from aqueous media using a batch technique. Raw glauconite (G), GL-CS/G, SDS-CS/G, EDTA-GL-CS/G, and CTAB-CS/G adsorbents displayed maximum adsorption capacity values of 1.15, 4.31, 4.55, 6.90, and 9.03 mg g−1, respectively. The adsorption results were well described by employing the pseudo-second-order kinetic and Langmuir isotherm models. The estimated thermodynamic constants indicated that the F− ion adsorption was a spontaneous, physisorption process. Furthermore, the modified chitosan adsorbents are good candidates for the adsorptive elimination of F− ions from aqueous solutions, according to their reusability, high stability, good adsorption capacity, and applicability for actual field water samples.We herein have developed a mild approach for the fabrication of glauconite clay (G)-modified chitosan (CS) nanocomposites by the combination of a simple blending and crosslinking method. 相似文献
77.
Mohamed A. Salem Rasha Ali Radwan Eman Sherien Mostafa Saleh Alseekh Alisdair R. Fernie Shahira M. Ezzat 《RSC advances》2020,10(52):31511
Aging is an unavoidable fate that afflicts all life, during this process in mammals reactive oxygen species (ROS) are generated which stimulate tyrosinase, elastase and collagenase activities that actively participate in skin aging. Therefore, the maintenance of antioxidant homeostasis is an important anti-aging strategy for skin. Nature has excellent anti-aging remedies that act externally as well as internally to delay the visual signs of aging. In view of this fact, the present study investigates the in vitro anti-aging activity of five medicinal plants belonging to phenolic rich families namely Rosmarinus officinalis, Lavandula officinalis, Matricaria chamomilla, Camellia sinensis and Pelargonium graveolens. The selected plants are those most frequently used in the preparation of ethnomedicinal recipes for the prevention or treatment of aging. The inhibitory effects of the ethanolic and aqueous extracts of the five selected plants on the activity of tyrosinase, elastase, and collagenase enzymes were investigated. Furthermore, the chemical composition of the plants and the antioxidant capacity of their extracts were assessed. The results showed that R. officinalis had the highest total phenolics content which was correlated with its potent antioxidant and anti-aging activities. To pinpoint the active metabolites in the tested extracts, we evaluated the metabolite variations using ultra-performance liquid chromatography coupled with high resolution electrospray ionization-tandem mass spectrometry (UPLC-HR-ESI-MS/MS). Multivariate data analysis (MVDA) revealed that R. officinalis significantly accumulated metabolites from the aromatic diterpenoid, flavonoid and phenolic acid classes. These results indicate that rosemary can be used for further development of topical preparations with anti-aging properties.Aging is an unavoidable fate that afflicts all life, during this process in mammals, reactive oxygen species (ROS) are generated which stimulate tyrosinase, elastase and collagenase activities that actively participate in skin aging. 相似文献
78.
79.
80.
Glutathione‐S‐transferase‐oxidative stress relationship in the internal spermatic vein blood of infertile men with varicocele
下载免费PDF全文
![点击此处可从《Andrologia》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This study aimed to assess glutathione‐S–transferase (GST) enzyme‐ oxidative stress (OS) relationship in the internal spermatic vein (ISV) of infertile men associated with varicocele (Vx). Ninety five infertile oligoasthenoteratozoospemic (OAT) men associated with Vx were subjected to history taking, clinical examination and semen analysis. During inguinal varicocelectomy, GST, malondialdehyde (MDA) and glutathione peroxidase (GPx) were estimated in the blood samples drawn from ISV and median cubital veins. The mean levels of GST, GPx were significantly decreased and the mean level of GPx was significantly increased in the ISV compared with the peripheral blood. The mean level of GST and GPx in the ISV was significantly decreased, and the mean level of MDA was significantly increased in Vx grade III compared with Vx grade II cases. There was nonsignificant difference in the mean level of GST in the ISV in unilateral Vx cases compared with bilateral Vx cases. There was significant positive correlation of GST with sperm count, sperm motility, GPx and significant negative correlation with sperm abnormal forms, MDA. It is concluded that ISV of infertile men associated with Vx has decreased levels of GST compared with peripheral venous circulation that is correlated with both OS and Vx grade. 相似文献