全文获取类型
收费全文 | 4414篇 |
免费 | 355篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 147篇 |
妇产科学 | 184篇 |
基础医学 | 587篇 |
口腔科学 | 206篇 |
临床医学 | 479篇 |
内科学 | 888篇 |
皮肤病学 | 197篇 |
神经病学 | 310篇 |
特种医学 | 104篇 |
外国民族医学 | 2篇 |
外科学 | 384篇 |
综合类 | 71篇 |
一般理论 | 8篇 |
预防医学 | 380篇 |
眼科学 | 99篇 |
药学 | 354篇 |
中国医学 | 51篇 |
肿瘤学 | 321篇 |
出版年
2024年 | 9篇 |
2023年 | 111篇 |
2022年 | 215篇 |
2021年 | 327篇 |
2020年 | 214篇 |
2019年 | 323篇 |
2018年 | 354篇 |
2017年 | 228篇 |
2016年 | 224篇 |
2015年 | 228篇 |
2014年 | 281篇 |
2013年 | 307篇 |
2012年 | 430篇 |
2011年 | 393篇 |
2010年 | 176篇 |
2009年 | 134篇 |
2008年 | 199篇 |
2007年 | 168篇 |
2006年 | 139篇 |
2005年 | 99篇 |
2004年 | 81篇 |
2003年 | 54篇 |
2002年 | 56篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 12篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1989年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1969年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有4801条查询结果,搜索用时 0 毫秒
991.
Responses of mesenchymal stem cell to chitosan-coralline composites microstructured using coralline as gas forming agent 总被引:1,自引:0,他引:1
Macroporous composites made of coralline:chitosan with new microstructural features were studied for their scaffolding potential in in vitro bone regeneration. By using different ratios of natural coralline powder, as in situ gas forming agent and reinforcing phase, followed by freeze-drying, scaffolds with controlled porosity and pore structure were prepared and cultured with mesenchymal stem cells (MSCs). Their supportive activity of cellular attachment, proliferation and differentiation were assessed through cell morphology studies, DNA content, alkaline phosphatase (ALP) activity and osteocalcin (OC) release. The coralline scaffolds showed by far the highest evaluation of cell number and ALP activity over all the other chitosan-based scaffolds. They were the only material on which the OC protein was released throughout the study. When used as a component of the chitosan composite scaffolds, these coralline's favourable properties seemed to improve the overall performance of the chitosan. Distinct cell morphology and osteoblastic phenotype expression were observed depending on the coralline-to-chitosan ratios composing the scaffolds. The coralline-chitosan composite scaffolds containing high coralline ratios generally showed higher total cell number, ALP activity and OC protein expression comparing to chitosan scaffolds. The results of this study strongly suggest that coralline:chitosan composite, especially those having a high coralline content, may enhance adhesion, proliferation and osteogenic differentiation of MSCs in comparison with pure chitosan. Coralline:chitosan composites could therefore be used as attractive scaffolds for developing new strategies for in vitro tissue engineering. 相似文献
992.
Razzaghy-Azar M Moghimi A Sadigh N Montazer M Golnari P Zahedi-Shoolami L Van Buuren S Mohammad-Sadeghi H Zangeneh-Kazemi A Fereshtehnejad SM 《Annals of human biology》2006,33(5-6):628-633
The aim of this study was to determine the age of appearance of secondary sexual characteristics in Iranian girls living in Tehran. A cross-sectional study was conducted between 2003 and 2004 on 1420 6-17-year-old females in different parts of Tehran. Data were collected on the basis of a multistage probability sampling. Secondary sexual characteristics were evaluated by inspection and palpation, and were recorded according to Tanner staging. The subjects were asked about the occurrence of menarche and the age of its onset. Generalized additive logistic modelling was used for the analysis of data. The median age (percentile 10-percentile 90) of Tanner 2 of breast development (B2) and Tanner 2 of pubic hair growth (P2) among 1136 girls was 9.74 years (8.23-11.94) and 10.49 years (8.86-12.17), respectively. The ages of the 2.5 percentile for B2 and P2 were 7.42 and 7.03 years, respectively, so the onset of puberty at < 7 years and 5 months is considered precocious in this population. The median age of menarche in 399 girls was 12.68 years (11.27-15.96). 相似文献
993.
Fabry disease: guidelines for the evaluation and management of multi-organ system involvement. 总被引:5,自引:0,他引:5
Christine M Eng Dominique P Germain Maryam Banikazemi David G Warnock Christoph Wanner Robert J Hopkin Jan Bultas Philip Lee Katherine Sims Scott E Brodie Gregory M Pastores Joerg M Strotmann William R Wilcox 《Genetics in medicine》2006,8(9):539-548
Fabry disease is an X-linked metabolic storage disorder due to the deficiency of lysosomal alpha-galactosidase A, and the subsequent accumulation of glycosphingolipids, primarily globotriaosylceramide, throughout the body. Males with classical Fabry disease develop early symptoms including pain and hypohidrosis by the second decade of life reflecting disease progression in the peripheral and autonomic nervous systems. An insidious cascade of disease processes ultimately results in severe renal, cardiac, and central nervous system complications in adulthood. The late complications are the main cause of late morbidity, as well as premature mortality. Disease presentation in female heterozygotes may be as severe as in males although women may also remain asymptomatic. The recent introduction of enzyme replacement therapy to address the underlying pathophysiology of Fabry disease has focused attention on the need for comprehensive, multidisciplinary evaluation and management of the multi-organ system involvement. In anticipation of evidence-based recommendations, an international panel of physicians with expertise in Fabry disease has proposed guidelines for the recognition, evaluation, and surveillance of disease-associated morbidities, as well as therapeutic strategies, including enzyme replacement and other adjunctive therapies, to optimize patient outcomes. 相似文献
994.
Utility of immunohistochemistry for alpha-methylacyl-CoA racemase in distinguishing atrophic prostate cancer from benign atrophy 总被引:1,自引:0,他引:1
Small atrophic prostate cancers on needle biopsy are rare and difficult to distinguish from benign atrophy on needle biopsy. We report on a study of 23 needle biopsy specimens with small foci of atrophic prostate cancer from the consult service of one of the authors. In 19 cancer cases the atrophic component was pure; in 4 cases it was dominant with a minor (<5%) nonatrophic cancer component. These atrophic cancers and 16 cases of florid benign atrophy on needle biopsy were examined by immunohistochemistry for alpha-methylacyl-CoA-racemase (AMACR). All cases of cancer and atrophy were verified immunohistochemically with antibodies to basal cells (34betaE12 and p63). AMACR staining were scored as 1+ (5% to 25% of glands expressing AMACR), 2+ (26% to 50% of glands expressing AMACR), or 3+ (>50% of glands expressing AMACR). Positive staining was defined as staining above that of surrounding benign glands. AMACR was expressed in 69.6% of atrophic prostate cancers (3+, 11 cases; 2+, 3 cases; 1+, 2 cases); 30.4% (7 cases) of atrophic prostate cancer exhibited no AMACR expression. In the 4 cases with a few glands of ordinary (nonatrophic) prostate cancer, the nonatrophic cancer demonstrated more intense and a greater extent of AMACR staining. Fourteen cases (87.5%) of benign atrophy showed no AMACR expression. In 2 cases (12.5%) of benign atrophy, background immunostaining made it difficult to assess AMACR expression. We conclude that AMACR immunostaining alone is not sufficiently discriminatory in the differential diagnosis of atrophic prostate cancer versus benign atrophy. Atrophic prostate cancers are not as frequently or as strongly positive as ordinary prostate cancer. Using a panel of immunostains including AMACR, 34betaE12 and p63 (positive AMACR immunostaining along with negative basal cell markers) is recommended in the differentiation of atrophic prostate cancer and benign atrophy. 相似文献
995.
Navid Jamali Zohreh Mostafavi-Pour Fatemeh Zal Maryam Kasraeian Tahereh Poordast Negar Nejabat 《Taiwanese journal of obstetrics & gynecology》2021,60(2):216-220
ObjectiveConsidering the role of oxidative stress in the development and progression of endometriosis, the ameliorative effect of caffeic acid treatment on ectopic, eutopic endometrial cells enzyme activities was investigated. We also determined the underlying cellular mechanisms.Materials and methodsEctopic endometrial specimens were collected from women with confirmed cases of endometriosis (n = 10) and eutopic specimens from (n = 10) controls. Following endometrial cell isolation and culture, eutopic and ectopic endometrial cells were treated with caffeic acid. Then, reactive oxygen species (ROS) level, NAD(P)H quinone oxidoreductase 1 (NQO1), and Heme oxygenase 1 (HO-1) enzyme activities, nuclear factor erythroid 2-related factor 2 (Nrf-2) gene expression were measured.ResultsIn ectopic endometrial cells, caffeic acid caused a significant elevation in Nrf-2 gene expression level, NQO1, and HO-1 enzyme activities. In addition, reduced ROS level was observed in caffeic acid-treated ectopic endometrial cells in comparison with the control. On the contrary, we did not observe any significant changes in caffeic acid-treated eutopic endometrial ones.ConclusionCaffeic acid can protect the endometrial cells against oxidative stress and might be able to prevent the progression of endometriosis and its related complications, such as pain and infertility. 相似文献
996.
Maryam Qasemi Reza Mahdian Fardin Amidi 《Journal of assisted reproduction and genetics》2021,38(2):277
Cell-free DNAs (cfDNAs) are fragmented forms of DNA that are released into extracellular environments. Analyzing them, regarding either concentration or genetic/epigenetic status can provide helpful information about disorders, response to treatments, estimation of success rates, etc. Moreover, since they are presented in body fluids, evaluation of the aforementioned items would be achieved by less/non-invasive methods. In human reproduction field, it is required to have biomarkers for prediction of assisted reproduction techniques (ART) outcome, as well as some non-invasive procedures for genetic/epigenetic assessments. cfDNA is an appropriate candidate for providing the both approaches in ART. Recently, scientists attempted to investigate its application in distinct fields of reproductive medicine that resulted in discovering its applicability for biomarker and genetic/epigenetic analyses. However, due to some limitations, it has not reached to clinical administration yet. In this article, we have reviewed the current reported data with respect to advantages and limitations of cfDNA utilization in three fields of ART, reproduction of male and female, as well as in vitro developed embryos. 相似文献
997.
Anne Bartels MD Julie Bykowski MD Kevin Brumund MD Maryam Pezhouh MD Vera Vavinskaya MD Grace Lin MD PhD Farnaz Hasteh MD Jingjing Hu MD PhD 《Diagnostic cytopathology》2023,51(2):E75-E81
B3 thymoma is a rare malignant type of thymic epithelial neoplasm found in the anterior mediastinum. Diagnosis of thymoma from fine needle aspiration (FNA) can be challenging due to the infrequency of sampling and its morphologic overlap with other entities such as squamous cell carcinoma, lymphoma or thyroid carcinoma. We report a case of B3 thymoma mimicking poorly differentiated thyroid carcinoma. We present its diagnostic pitfalls on cytology specimens, especially where it concerns identifying the correct location of the lesion, discuss the differential diagnosis, and correlation with the corresponding surgical resection specimen. A neck computed tomography angiogram (CTA) revealed a partially calcified 2.1 cm mass inferior to the left thyroid lobe in a 51 yr old woman being evaluated for stroke/TIA symptoms. She was referred for evaluation of the lesion. On the initial FNA and core needle biopsy, the lesion showed high-grade epithelioid cells with abundant lymphocytic infiltration and occasional necrosis, and was diagnosed as a high-grade carcinoma, favored to represent a poorly differentiated thyroid carcinoma considering the location on imaging. The patient subsequently underwent total thyroidectomy, central neck dissection, and thymectomy. Final surgical pathologic diagnosis indicated a type B3 thymoma. Due to the infrequency of sampling, thymoma poses a diagnostic challenge on preoperative FNA or core needle biopsy. Herein, we present a case of B3 thymoma with a preoperative cytologic specimen that consisted of hyperchromatic sheets of epithelioid tumor cells with a background of lymphocytes without definitive follicular cells or colloid. The core needle biopsy and cell block material showed abundant necrosis, intermixed lymphocytes and neoplastic epithelial cells with strong positive staining for pan-keratin and p40. The cytology and core needle biopsy material were interpreted as representing a probable thyroid neoplasm and raised a broad differential including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma with squamous features, metastatic squamous carcinoma, and metastatic carcinoma to a lymph node. The final surgical resection specimen showed a B3 type-thymoma. 相似文献
998.
Liubov O. Skorodumova Ksenia A. Davydenko Alexandra Y. Filatova Mikhail Yu Skoblov Nikolay A. Kulemin Maryam B. Khadzhieva Elena S. Zakharova Veronika D. Gordeeva Nataliya S. Smetanina Irina V. Fedyushkina Lyudmila A. Anastasevich Sergey S. Larin 《Clinical genetics》2023,103(1):93-96
Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by erythroid aplasia. Pathogenic variants in ribosomal protein (RP) genes, GATA1, TSR2, and EPO, are considered to be the etiology of DBA. Variants in 5′-untranslated regions (UTRs) of these genes are poorly studied and can complicate the variant interpretation. We investigated the functional consequences NM_001011.4:c.-19 + 1G > T variant in the donor splice-site of the RPS7 5′-UTR. This variant was found in a family where two sons with DBA were carriers. Father, who also had this variant, developed myelodysplastic syndrome, which caused his death. Search for candidate causal variants and copy number variations in DBA-associated genes left RPS7 variant as the best candidate. Trio whole exome sequencing analysis revealed no pathogenic variants in other genes. Functional analysis using luciferase expression system revealed that this variant leads to disruption of splicing. Also, a decrease in the levels of mRNA and protein expression was detected. In conclusion, the established consequences of 5′-UTR splice-site variant c.-19 + 1G > T in the RPS7 gene provide evidence that it is likely pathogenic. 相似文献
999.
Diaz-Montes TP Farinola MA Zahurak ML Bristow RE Rosenthal DL 《Gynecologic oncology》2007,104(2):366-371
OBJECTIVES: To determine the utility of the category of atypical glandular cells (AGC) in the management of patients with putative cervical neoplasia and to correlate HPV-DNA test results when available. METHODS: The Johns Hopkins Hospital cytopathology records of 50,668 women patients were searched for all liquid-based gynecologic cytology (LBP) results of Atypical Glandular cells of Undetermined Significance (AGUS) and AGC from January 1, 2001 through December 31, 2003, yielding 98 patients (0.19%). Oncogenic HPV-DNA tests were performed on the residual fluids of 43 of these patients, 37 of whom had follow-up biopsy. During the period of January 1, 2000 and December 31, 2002, we identified 237 patients (0.58%) with conventional Pap smears in the AGUS or AGC category, among 41,024 conventional smears collected contemporaneously. To avoid confusion in this paper, AGC will be used to replace those results that originally were AGUS. RESULTS: Following the 98 LBP AGC interpretations, 24 lesions (33.8%) were discovered out of 71 biopsies. HPV-DNA tests were performed on the residual of 43 LBPs, 18 (41.9%) were positive for oncogenic HPV. Only 37 patients had follow-up biopsy and 15 (40.5%) were positive for oncogenic HPV, of which 40% (6/15) had a significant lesion. Of the 237 conventional AGC Paps, 18 lesions (15.3%) were discovered out of 118 biopsies. CONCLUSIONS: Comparison of liquid-based and conventional Pap tests revealed a significant difference (33.8% vs. 15.3% respectively) (OR: 2.84, 95% CI: 1.4-5.73, p=0.004) in the detection of glandular and squamous lesions. HPV testing may prove beneficial to triage AGC patients with negative colposcopic findings and positive HPV results. 相似文献
1000.
Hamid Amoozgar Sirous Cheriki Mohammad Borzoee Gholamhossein Ajami Manouchehr Soltani Maryam Ahmadipour Farah Peiravian Amirali Amirghofran 《Pediatric cardiology》2012,33(8):1288-1294
This report aims to compare the researchers?? early experience with the safety, efficacy, short-term outcomes, and complications of patent ductus arteriosus (PDA) stents in neonates having duct-dependent pulmonary circulation with those of surgically created shunts. Between April 2009 and April 2011, 18 infants with duct-dependent pulmonary circulation underwent cardiac catheterization for PDA stenting as the first palliative procedure in a referral center. For comparison, 20 infants who underwent surgical aortopulmonary shunt placement in another center were used. Follow-up assessment included clinical examination, echocardiography, oxygen saturation, and cardiac catheterization studies. Access and stenting for the PDA were successful in 15 patients (83.3?%). The mean procedure time was 58.43?±?41.25?min, and the mean fluoroscopy time was 18.81?±?5.64?min. Three patients (20?%) in the stented group and 6 patients (30?%) in the surgical group died (P?=?0.09). After a 6-month follow-up period, none of the patients had significant stent stenosis requiring reintervention. The oxygen saturation increase did not differ significantly between the two groups either immediately after the procedure or 6?months later (P?>?0.5). The left pulmonary artery diameter, McGoon ratio, and Nakata index did not differ significantly between the two groups (P?>?0.05), but the right pulmonary diameter was larger in the stented group (5.01?±?0.45 vs 4.1?±?0.49?mm; P?=?0.0001). Stenting for the PDA is an appropriate alternative to surgical shunt creation in many patients with duct-dependent circulation. In our sample, the two groups did not differ significantly in terms of outcome or mortality. 相似文献