首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   24222篇
  免费   2339篇
  国内免费   1179篇
耳鼻咽喉   378篇
儿科学   306篇
妇产科学   410篇
基础医学   5467篇
口腔科学   744篇
临床医学   1466篇
内科学   3453篇
皮肤病学   435篇
神经病学   1432篇
特种医学   505篇
外科学   2733篇
综合类   3332篇
预防医学   935篇
眼科学   385篇
药学   2277篇
  3篇
中国医学   627篇
肿瘤学   2852篇
  2023年   173篇
  2022年   387篇
  2021年   590篇
  2020年   496篇
  2019年   409篇
  2018年   538篇
  2017年   620篇
  2016年   860篇
  2015年   982篇
  2014年   1359篇
  2013年   1647篇
  2012年   1467篇
  2011年   1657篇
  2010年   1396篇
  2009年   1461篇
  2008年   1541篇
  2007年   1565篇
  2006年   1486篇
  2005年   1319篇
  2004年   1035篇
  2003年   966篇
  2002年   742篇
  2001年   655篇
  2000年   569篇
  1999年   485篇
  1998年   350篇
  1997年   326篇
  1996年   270篇
  1995年   276篇
  1994年   260篇
  1993年   225篇
  1992年   187篇
  1991年   146篇
  1990年   141篇
  1989年   146篇
  1988年   132篇
  1987年   111篇
  1986年   82篇
  1985年   88篇
  1984年   91篇
  1983年   47篇
  1982年   72篇
  1981年   65篇
  1980年   59篇
  1979年   46篇
  1978年   44篇
  1977年   27篇
  1976年   26篇
  1973年   19篇
  1972年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
IntroductionThe main aim of this study was to assess the utility of differential white cell count and cell population data (CPD) for the detection of COVID-19 in patients admitted for community-acquired pneumonia (CAP) of different etiologies.MethodsThis was a multicenter, observational, prospective study of adults aged ≥18 years admitted to three teaching hospitals in Spain from November 2019 to November 2021 with a diagnosis of CAP. At baseline, a Sysmex XN-20 analyzer was used to obtain detailed information related to the activation status and functional activity of white cells.ResultsThe sample was split into derivation and validation cohorts of 1065 and 717 patients, respectively. In the derivation cohort, COVID-19 was confirmed in 791 patients and ruled out in 274 patients, with mean ages of 62.13 (14.37) and 65.42 (16.62) years, respectively (p < 0.001). There were significant differences in all CPD parameters except MO-Y. The multivariate prediction model showed that lower NE-X, NE-WY, LY-Z, LY-WY, MO-WX, MO-WY, and MO-Z values and neutrophil-to-lymphocyte ratio were related to COVID-19 etiology with an AUC of 0.819 (0.790, 0.846). No significant differences were found comparing this model to another including biomarkers (p = 0.18).ConclusionsAbnormalities in white blood cell morphology based on a few cell population data values as well as NLR were able to accurately identify COVID-19 etiology. Moreover, systemic inflammation biomarkers currently used were unable to improve the predictive ability. We conclude that new peripheral blood biomarkers can help determine the etiology of CAP fast and inexpensively.  相似文献   
2.
《Survey of ophthalmology》2023,68(5):940-956
Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management. Here, we review the current understanding about the pathogenesis and management of AAK. We highlight the biological mechanisms involved in AAK development with the aim to develop future treatment options, including surgical, pharmacological, cell therapies, and gene therapies.  相似文献   
3.
目的 探讨蜂巢提取物Elixir-X对自然衰老及辐射衰老小鼠的影响,为Elixir-X的进一步研发提供药理学基础。方法 采用小鼠肝脏切除术建立自然衰老小鼠模型,将其分为空白对照组、Elixir-X组、白藜芦醇组及模型组,连续给药7 d后,检测小鼠70%肝脏切除后的再生过程中,衰老细胞、肝脏功能恢复与肝脏再生的变化,观察Elixir-X对自然衰老的影响;采用60CO辐射法建立辐射衰老小鼠模型,将其分为模型组、空白对照组、白藜芦醇组、Elixir-X高、低剂量组,通过检测小鼠肠隐窝干细胞再生、小肠绒毛结构以及衰老细胞的变化,对比不同剂量Elixir-X对辐射后衰老的影响。结果 在肝脏切除术的小鼠模型中,Elixir-X组的肝功能水平明显低于模型组的肝脏自然再生小鼠,显著促进了肝功能恢复(P<0.05);同时与模型组相比,Elixir-X组清除了肝脏切除后再生过程中产生的衰老细胞(P<0.05),Ki-67的着色斑块明显增加,促进肝脏的再生,且肝血窦的扫描电镜影像结果中Elixir-X组肝血窦再生加快。60CO辐照小鼠模型中,与模型组相比,Elixir-X组有效促进辐照后肝脏功能恢复(P<0.05),Elixir-X高剂量组体重也恢复到正常水平,与空白对照组无显著差异;与模型组相比,Elixir-X低剂量组小肠的β-Gal着色细胞减少,Elixir-X高剂量组甚至能更有效地减少衰老细胞(P<0.05);小肠HE染色的结果中,Elixir-X组小肠绒毛结构得到恢复;Ki-67的IHC染色中,与模型组相比,Elixir-X组着色板块更多,且着色区域都在肠隐窝干细胞位置。结论 Elixir-X能有效清除肝脏切除术引起的自然衰老与辐射引起的损伤性衰老细胞,对衰老具有显著地抑制作用。  相似文献   
4.
5.
6.
目的探究肾透明细胞癌不同CT影像学征象对患者术后康复情况的影响。方法选取2010年1月到2014年4月我院收治的50例肾透明细胞癌患者的CT征象,进行T分期,并分析不同CT征象与患者预后关系。结果利用CT征象进行T分期区别主要在T3a期,T3a期分为T3a-CT(10例)和T3a-仅病理(6例),T3a-仅病理CT分期可分为T1期2例,T2期4例;单因素分析显示,肿瘤大小、肿瘤是否侵及肾被膜外、是否侵及肾窦集合系统、是否侵及肾静脉及分支、是否侵及下腔静脉、有无广泛性坏死、是否存在囊性改变、瘤周是否受侵、瘤周是否存在新生血管与5年生存率具有一定相关性(P<0.05);多因素回归分析显示,肿瘤≥7cm、肿瘤穿透肾被膜、肾静脉及分支受侵、下腔静脉受侵、肿瘤无囊变、瘤周受侵及瘤周新生血管是影响肾透明细胞癌预后的独立危险因素(P<0.05)。结论肾透明细胞瘤患者肿瘤大于7cm、肿瘤穿透肾被膜、肾静脉及分支受侵、下腔静脉受侵、肿瘤无囊变、瘤周受侵及瘤周新生血管是影响肾透明细胞癌预后的独立危险因素,肿瘤周围受侵及瘤周新生血管形成可降低患者5年生存率,而肿瘤囊变可作为预测术后康复情况较好的标志之一。  相似文献   
7.
《Survey of ophthalmology》2022,67(6):1647-1684
Managing pediatric corneal disorders is challenging as the prognosis of pediatric keratoplasty depends on several factors. Advancements in the genetic basis of congenital corneal diseases and investigations in congenital corneal conditions provide a better understanding of pediatric corneal conditions. Surgeons performing keratoplasty in children now have a choice of various techniques. Evolving surgical techniques of anterior lamellar and endothelial keratoplasties have expanded the management interventions in these pediatric corneal morbidity conditions; however, considerable concerns still exist in association with corneal transplantation in infants and children. Outcomes in pediatric keratoplasty depend upon the preoperative indications, the timing of surgical intervention, intraoperative and postoperative factors including the patient/care givers’ compliance. Factors such as low scleral rigidity, higher rate of graft failure, need for frequent examinations under anesthesia, and difficulty in optimal visual acuity assessment still remain a considerable challenge in pediatric scenarios. In children, deprivation amblyopia as a result of the corneal opacification can adversely affect visual development, causing dense amblyopia. Outcomes to surgical interventions for management of corneal opacification in children are further compromised by the preexisting amblyopia apart from the concerns of refractive outcome of the graft. Graft rejection, graft infection, amblyopia, and glaucoma continue to be serious concerns. In recent years both anterior and posterior lamellar keratoplasty techniques are being increasingly performed in pediatric eyes, which offer advantages in the form of lower risk of graft rejection. The timing of surgery, careful case selection, cautious intraoperative approach, and optimal postoperative management can improve the anatomical and functional outcome in difficult cases.  相似文献   
8.
目的建立人髌下脂肪垫干细胞分离、培养和鉴定的平台,验证其可作为可靠的干细胞来源,并可作为细胞模型参与科学研究。 方法人髌下脂肪垫取自膝关节置换手术患者,经Ⅰ型胶原酶消化,在高糖Dulbecco改良Eagle培养基(DMEM)内扩增,取P5代细胞用于检测其"干性"及三向分化能力。与微尺度支架结合,通过RT-PCR检测成骨基因的表达,应用最小显著性差异法进行组间两两比较,用于验证微尺度支架的成骨诱导特性。 结果人髌下脂肪垫干细胞具备间充质干细胞相关特性,包括黏附贴壁性;成脂肪、成软骨及成骨分化;表达相关表面标记,如分化抗原簇(CD)73、CD90和CD105;不表达造血细胞系的分子表面标记,如c-kit、CD14、CD11b、CD34、CD45、CD19、CD79和人白细胞抗原(HLA)-DR。本课题中人髌下脂肪垫来源干细胞成功作为一种干细胞模型,证明HaCG微尺度支架具备成骨诱导特性,表现为三组中成骨基因ALP、COL1、Runx2表达差异有统计学意义(分别为F=150,P<0.01;F=68,P<0.01;F=16,P<0.01)。HaCG微尺度支架组高于纯明胶微尺度支架组及二维培养组,纯明胶微尺度支架组高于二维培养组(P值均小于0.05)。 结论人髌下脂肪垫干细胞分离、培养和鉴定平台的建立,未来可作为细胞模型应用于多种不同实验。  相似文献   
9.
Introduction: We present a case of a sickle cell patient who presented with Urrets-Zavalia Syndrome (UZS) like characteristics without having undergone any surgical procedures.

Case report: A 41-year-old woman diagnosed with sickle cell thalassemia presented with glaucoma of the both eyes. Visual acuity was decreased in both eyes. Epithelial edema was observed in corneas of both eyes, most prominently in the left eye. Peripheral anterior synechiae were present bilaterally. Intraocular pressure was measured to be 26 mmHg in the right eye and 36 mmHg in the left eye. Fixed dilated pupils were observed in both eyes. Fluorescein angiography revealed ischemia of the iris in the right eye.

Conclusion: Physicians should keep a high suspicion of UZS in all patients with fixed dilated pupils, especially in sickle cell disease, regardless of having undergone ophthalmic surgeries or not.  相似文献   

10.
The pituitary tumor-transforming gene 1 (PTTG1), also known as Securin, is considered an oncogene. This study aimed to investigate the role of PTTG1 in clear cell renal cell carcinoma (ccRCC) using in silico bioinformatics approaches. A pan-cancer analysis using The Cancer Genome Atlas (TCGA) data indicated that among all cancer types copy number amplification of PTTG1 gene was most frequently found in ccRCC. However, amplification of PTTG1 gene copy number did not correlate with the increase of mRNA level in ccRCC, and did not predict the patients' overall survival. Instead, ccRCC was correlated with overexpression of PTTG1 mRNA, and its expression level was stage-dependent increased in cancer patients. An outlier analysis using the Oncomine database suggested that PTTG1 mRNA expression served as a good biomarker for ccRCC. Pathway analysis for upregulated genes enriched in PTTG1-high expressing ccRCC patients found that PTTG1 overexpression was associated with mitotic defects. Mining drug sensitivity data using the Cancer Therapeutics Response Portal (CTRP) discovered that PTTG1-high expressing ccRCC cell lines were susceptible to a Rac1 (Ras-related C3 botulinum toxin substrate 1) inhibitor NSC23766. Therefore, this study provides an in silico insight into the role of PTTG1 in ccRCC, and repurposes the Rac1 inhibitor NSC23766 for treating PTTG1-high expressing ccRCC.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号