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   12481篇
  免费   833篇
  国内免费   365篇
耳鼻咽喉   462篇
儿科学   184篇
妇产科学   228篇
基础医学   1095篇
口腔科学   967篇
临床医学   1065篇
内科学   1695篇
皮肤病学   319篇
神经病学   1274篇
特种医学   772篇
外国民族医学   4篇
外科学   1358篇
综合类   1627篇
现状与发展   1篇
预防医学   388篇
眼科学   147篇
药学   492篇
  5篇
中国医学   223篇
肿瘤学   1373篇
  2024年   22篇
  2023年   205篇
  2022年   377篇
  2021年   525篇
  2020年   454篇
  2019年   411篇
  2018年   413篇
  2017年   414篇
  2016年   406篇
  2015年   410篇
  2014年   754篇
  2013年   649篇
  2012年   648篇
  2011年   688篇
  2010年   570篇
  2009年   619篇
  2008年   650篇
  2007年   684篇
  2006年   595篇
  2005年   487篇
  2004年   389篇
  2003年   372篇
  2002年   338篇
  2001年   303篇
  2000年   250篇
  1999年   207篇
  1998年   172篇
  1997年   191篇
  1996年   156篇
  1995年   138篇
  1994年   142篇
  1993年   109篇
  1992年   105篇
  1991年   79篇
  1990年   76篇
  1989年   69篇
  1988年   65篇
  1987年   58篇
  1986年   74篇
  1985年   96篇
  1984年   58篇
  1983年   33篇
  1982年   43篇
  1981年   42篇
  1980年   37篇
  1979年   20篇
  1978年   14篇
  1977年   10篇
  1976年   13篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Porocarcinoma (synonym: malignant eccrine poroma) is a rare aggressive carcinoma type with terminal sweat gland duct differentiation. The squamous variant of porocarcinoma is even less frequent and might be indistinguishable from conventional squamous cell carcinoma (SCC). We herein describe the first case of a carcinoma presenting as a primary parotid gland malignancy in a 24-year-old male without any other primary tumor. Total parotidectomy and neck dissection were performed followed by adjuvant chemoradiation. The patient remained alive and well 10 months after diagnosis. Histology showed keratinizing SCC infiltrating extensively the parotid gland with subtle poroid cell features. Oncogenic HPV infection was excluded by DNA-based testing. NGS analysis using the TruSight RNA fusion panel (Illumina) revealed a novel YAP1-MAML2 gene fusion. This gene fusion was reported recently in a subset of cutaneous porocarcinoma and poroma. This case of poroid SCC (or squamoid porocarcinoma) adds to the differential diagnosis of SCC presenting as parotid gland tumor and highlights the value of molecular testing in cases with unusual presentation.Electronic supplementary materialThe online version of this article (10.1007/s12105-020-01181-9) contains supplementary material, which is available to authorized users.  相似文献   
72.
The tumor immune microenvironment of oral tongue squamous cell carcinoma may be accountable for differences in clinical behavior, particularly between different age groups. We performed RNA expression profiling and evaluated tumor infiltrating lymphocytes (TILs) and their T-cell subsets in order to assess the functional status of oral tongue squamous cell carcinoma tumor microenvironment and detect potentially clinically useful associations. Archival surgical pathology material from sixteen oral tongue squamous cell carcinoma patients was microscopically evaluated for TIL densities. RNA was extracted from macrodissected whole tumor sections and normal controls and RNA expression profiling was performed by the NanoString PanCancer IO 360 Gene Expression Panel. Immunostains for CD4, CD8 and FOXP3 were evaluated manually and by digital image analysis. Oral tongue squamous cell carcinomas had increased TIL densities, numerically dominated by CD4 + T cells, followed by CD8 + and FOXP3 + T cells. RNA expression profiling of tumors versus normal controls showed tumor signature upregulation in inhibitory immune signaling (CTLA4, TIGIT and PD-L2), followed by inhibitory tumor mechanisms (IDO1, TGF-β, B7-H3 and PD-L1). Patients older than 44 years showed a tumor microenvironment with increased Tregs and CTLA4 expression. Immunohistochemically assessed CD8% correlated well with molecular signatures related to CD8 + cytotoxic T-cell functions. FOXP3% correlated significantly with CTLA4 upregulation. CTLA4 molecular signature could be predicted by FOXP3% assessed by immunohistochemistry (R2 = 0.619, p = 0.026). Oral tongue squamous cell carcinoma hosts a complex inhibitory immune microenvironment, partially reflected in immunohistochemically quantified CD8 + and FOXP3 + T-cell subsets. Immunohistochemistry can be a useful screening tool for detecting tumors with upregulated expression of the targetable molecule CTLA4.Electronic supplementary materialThe online version of this article (10.1007/s12105-020-01229-w) contains supplementary material, which is available to authorized users.  相似文献   
73.
IntroductionMorel-Lavallée lesions are closed degloving injuries in which the skin and subcutaneous tissues separate from the underlying fascia secondary to a shearing force. These injuries are uncommon and can be misdiagnosed in acute settings. If treated incorrectly, they can recur, causing complications requiring multiple surgical interventions. Therefore, it is important to discuss the clinical presentation and imaging characteristics in order to improve their diagnosis and management.Presentation of caseThis is the case of a 44-year-old male patient with a Morel-Lavallée lesion of the left thigh that presented 25 years after trauma. He was successfully treated with open surgical excision. The patient underwent multiple surgical interventions before the lesion was accurately diagnosed and treated.DiscussionMorel-Lavallée injuries can lead to chronic symptoms, such as pain and swelling, affecting the patient’s quality of life. Treatment options include minimally invasive procedures, such as compression bandages or percutaneous drainage. However, if diagnosed late, a fibrotic capsule can form, which may require surgical excision. Our patient was diagnosed more than 20 years after the trauma. Earlier noninvasive treatment options were unsuccessful.ConclusionThe patient was treated with open surgical excision of the chronic lesion. There was no report of any recurrence up to 10 months after surgery. Such lesion treatments should be guided based on the chronicity of the injury and the patient’s symptoms. To the best of our knowledge, this is the first case with such delayed presentation.  相似文献   
74.
Introduction and importanceSolid organ transplantation has evolved along with dramatic advancements in definitive treatment for irreversible and uncompensated organ failure. Transplanted organ survival has improved as a result of reduced allograft rejection. However, negative long-term outcomes which were largely due to the adverse effects of rapidly evolving immunosuppressive regimens are still evident. The emergence of malignancies following prolonged exposure to immunosuppression treatment has affected the quality of life in transplant recipients. They are approximately one hundred times more likely to develop squamous cell carcinoma (SCC) compared to the general population and the incidence of malignant melanomas, basal cell carcinomas, and Kaposi’s sarcomas are also on the rise. The incidence of de novo malignancies ranges from 9 to 21% and is commonly seen in the skin and the lymphoreticular system in these patients.Case presentationA 78-year-old male presented with a lump in the right axilla, which had grown in size over a 4-week period. Patient had received a cardiac transplant 9 years prior and was on a regimen of Tacrolimus and Mycophenolate Mofetil since then.Clinical discussionFollowing 4 years of immunosuppression therapy, the patient developed a non-healing ulcer on his right forearm and the biopsy confirmed SCC. The recent biopsy performed on the new axillary lump also confirmed SCC. Iatrogenic immune suppressive treatment is associated with the occurrence of de novo, non-melanoma skin cancers in the solid organ transplant recipients and this necessitates early and comprehensive cancer surveillance models to be included in the pre and post-transplant assessment.ConclusionAdvances in immunology suggest that peripheral blood mononuclear cell sequencing and immune profiling to identify immune phenotypes associated with keratinocyte cancers allow us to recognize patients who are more susceptible for SCC following organ transplantation and immunosuppression.  相似文献   
75.
IntroductionBreast cancer is the most common diagnosed cancer among women worldwide. Invasive ductal carcinoma (IDC) is the most common type, on the other hand, squamous cell carcinoma of the skin (SCC) overlying the breast is a rare tumor. The co-presence of two tumor types in one organ is even a rarer entity, termed as collision tumor. Only 3 known cases of collision tumor with breast invasive ductal and skin squamous carcinoma were reported in the literature.Case presentationAn otherwise medically free 91-year-old, postmenopausal, female presented with left breast fungating mass for four months. Pre-operative core tissue biopsy and incisional skin biopsy revealed two distinct tumor subtypes of invasive ductal carcinoma, positive for progesterone, estrogen receptors and negative for human epidermal growth factor receptor 2, as well as skin squamous cell carcinoma, and axillary lymph node metastasis. Patient underwent left breast modified radical mastectomy and split skin grafting for wound closure. The final histopathology was consistent with grade 2 IDC. The nipple and areola complex were involved by moderately differentiated squamous cell carcinoma. Currently patient on adjuvant hormonal treatment. Follow up showed no local recurrence or distal metastasis.ConclusionCollision tumors of the breast with IDC and SCC of the overlying skin is very rare. The surgeon has to be aware of of such entity as the proper peri-operative management should be tailored to target the most aggressive histologic subtype.  相似文献   
76.
声学密度定量分析技术评价尿毒症性心肌损害的临床研究   总被引:1,自引:0,他引:1  
目的:探讨声学密度定量分析技术在尿毒症性心肌损害诊断方面的定量诊断价值。方法:对21例尿毒症及21例正常人心肌各节段声学密度及心肌声学密度校正值(IB%)进行测定及比较。结果:尿毒症患者心肌各节段平均声学密度(AⅡ)均明显高于正常人(P<0.01),2组的峰值-峰值密度(PPI)及标准密度差(SDI)差异不显著(P>0.05),2组左心腔内PPI、AⅡ、SDI差异均不显著(P>0.05),尿毒症组心肌各节段IB%明显高于正常人(P<0.01)。结论:声学密度定量分析技术能定量、客观地反映尿毒症患者的心肌损害情况,对临床检测尿毒症 损害具有实用价值。  相似文献   
77.
胃癌前组织和胃癌中Fas基因表达及其与细胞凋亡的关系   总被引:4,自引:0,他引:4  
目的 探讨胃癌组织及胃癌中Fas基因表达状况及其与细胞凋亡的关系。方法 应用原位杂交和免疫组织化学技术检测10例正常胃粘膜、72例慢性胃炎和53例胃癌中Fas基因的表达,并采用凋亡细胞原位检测方法对组织切片中的凋亡细胞进行观察和比较。结果 正常胃粘膜无Fas基因表达。Fas mRNA在肠化生组织中的表达率为75.00%,显著高于萎缩性胃炎(37.50%,P<0.01)和胃癌(52.83%,P<0.05)。Fas蛋白在肠化生组织中的表达率为80.56%,显著高于萎缩性胃炎(37.50%,P<0.01)、异型增生(55.00%,P<0.05)和胃癌(45.28%,P<0.01)。X^2检验表明两种方法检测阳性率差异无显著性。凋亡细胞原位检测结果显示,Fas蛋白表达阳性萎缩性胃炎、肠化生和胃癌组织中的凋亡细胞指数显著高于Fas蛋白阴性组(P<0.05及P<0.01),Fas蛋白表达状态与细胞凋亡指数呈正相关(r=0.393,P<0.01)。结论 Fas基因对胃癌前组织及胃癌细胞凋亡具有促进性调控作用,细胞凋亡调控异常在胃癌发病中可能起重要作用。  相似文献   
78.
目的:通过鞘内注射不同剂量的胶原酶,观察其对脊髓及周围组织的损伤作用。方法:把40只兔分成A、B、C、D、E5组,分别在鞘内注射0.3mL的生理盐水和24、50、100、250U的胶原酶,通过形态学、脊髓诱发电位和组织病理学的检查以观察胶原酶对上述组织的损伤。结果:鞘内注射胶原酶的4组兔中都有不同程度的瘫痪,没有瘫痪的兔其SCEP也有改变,病检发现脊髓、神经根和血管都有不同程度的损伤,胶原酶剂量越大,损伤越重。结论:胶原酶鞘内注射对兔脊髓及其周围组织有严重的损伤作用。  相似文献   
79.
胃癌及癌前病变组织中雌激素受体和P21ras的表达及意义   总被引:1,自引:0,他引:1  
目的 探讨雌激素受体(ER)和ras原癌基因蛋白-P2ras的表达在胃癌发生、发展中的作用及与胃癌生物学行为的关系。方法 采用免疫组化SP法。结果 ER在慢性浅表性胃炎(20例)、异型增生(21例)中均为阴性,胃癌(40例)的表达阳性率为40%,三组比较有显著性差异(I〈0.05)。P21^ras在慢性浅表性胃炎、异型增生、胃癌的表达阳性率分别为10%、23.8%、47.5%,三组比较差异有显著性  相似文献   
80.
目的 检测雌激素受体(ER)在胃癌的表达及其与胃癌生物学行为的关系。方法 应用免疫组化S-P法。结果 ER在慢浅表性胃炎、异型增生中表达均为阴性,在胃癌阳性率为40%,三组 比较比较有显著性差异(P〈0.05)。ER在进展期胃癌的阳性率显著高于早期胃癌(P〈0.05)。胃癌有淋巴结转移组的阳性率显著高于无淋巴结转移组(P〈0.05)。ER的表达在分化不良型胃癌高于分化型胃癌,但无统计学意义(P〉0  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