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   22578篇
  免费   1823篇
  国内免费   390篇
耳鼻咽喉   156篇
儿科学   784篇
妇产科学   75篇
基础医学   4145篇
口腔科学   183篇
临床医学   1552篇
内科学   5042篇
皮肤病学   1504篇
神经病学   443篇
特种医学   495篇
外国民族医学   17篇
外科学   999篇
综合类   1652篇
现状与发展   4篇
预防医学   439篇
眼科学   278篇
药学   891篇
  3篇
中国医学   149篇
肿瘤学   5980篇
  2024年   25篇
  2023年   410篇
  2022年   565篇
  2021年   881篇
  2020年   892篇
  2019年   854篇
  2018年   802篇
  2017年   803篇
  2016年   727篇
  2015年   934篇
  2014年   1283篇
  2013年   1483篇
  2012年   1042篇
  2011年   1084篇
  2010年   886篇
  2009年   936篇
  2008年   1081篇
  2007年   1049篇
  2006年   959篇
  2005年   908篇
  2004年   685篇
  2003年   680篇
  2002年   571篇
  2001年   545篇
  2000年   473篇
  1999年   407篇
  1998年   387篇
  1997年   374篇
  1996年   372篇
  1995年   329篇
  1994年   301篇
  1993年   225篇
  1992年   253篇
  1991年   246篇
  1990年   187篇
  1989年   161篇
  1988年   149篇
  1987年   120篇
  1986年   95篇
  1985年   164篇
  1984年   91篇
  1983年   44篇
  1982年   89篇
  1981年   65篇
  1980年   35篇
  1979年   39篇
  1978年   31篇
  1977年   18篇
  1976年   16篇
  1966年   5篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
251.
A coordinated triggering task requiring use of kinesthetic information was employed to assess the timing of use of kinesthetic information in normal subjects and patients with cerebellar dysfunction. Passive movements of varying velocity were imposed in the flexor direction about the metacarpophalangeal joint of the right index finger. Subjects attempted to depress a switch with their left thumb when the index finger moved, past a specified angle that was learned during a training session. The velocities ranged from 10°/s to 88°/s in 2°/s increments. After 200 trials, subjects were then instructed instead to react as quickly as possible (reaction-time task) to the onset of movement for an additional 200 trials. For the same movements, the timing of onset of responses of muscle spindle afferents and cutaneous mechanoreceptors was determined by recording the responses of these afferents using microneurography. For slow velocities, patients were able to perform similarly to normals but at faster velocities patients triggered too late compared with normals. Patients required more time to use kinesthetic information than did normal subjects. An estimate of kinesthetic processing was not longer in patients. The chief explanation for the prolonged time required to use kinesthetic information in patients was that their reaction times were prolonged by 93 ms. In addition, the movement time was also prolonged, but this accounted for only 23 ms. Impaired motor performance in tasks requiring the use of kinesthetic information in cerebellar patients can be explained largely by their prolonged reaction times. Muscle spindle afferents responded on average much sooner than cutaneous mechanoreceptors. Because of the limited time available to perfomr the kinesthetic triggering task, the role for cutaneous mechanoreceptors, to provide singals for on-line coordination of movement appears limited compared with muscle spindle afferents.  相似文献   
252.
《Human immunology》2022,83(3):219-224
To date, traditional pre-transplant risk factors have failed to provide accurate risk stratification in transplantation. As a result, the practice of precision medicine remains elusive, resulting in a one-size-fits-all therapeutic approach for most patients. However, recent advancements in the understanding of HLA molecules at the molecular level have revitalized interest in HLA mismatch assessment. This review discusses HLA molecular mismatch as a potential prognostic and predictive biomarker available at the time of transplantation and answers some of the common questions and critiques of this approach. We highlight the retrospective data that supports single molecule risk categorization and explore the next steps required to evaluate its potential in clinical practice.  相似文献   
253.
A case in which malignant lymphoma occurred in association with a tuberculosis focus in a 70-year-old man is reported. Surrounding the epithelioid cell granulomas with caseous necrosis was a dense and diffuse monotonous infiltration of atypical lymphoid cells. Acid-fast bacilli were found in the granulomas and pulmonary tuberculosis was diagnosed. The infiltrating atypical lymphoid cells occasionally invaded the respiratory epithelium producing lymphoepithelial lesions. Immunohistochemically, the lymphoid cells were positive for CD20, and clonal rearrangement of the immunoglobulin heavy chain gene was demonstrated by polymerase chain reaction (PCR). We diagnosed the lesion as a pulmonary malignant lymphoma of bronchus-associated lymphoid tissue (BALT) occurring in the background of tuberculosis. This is the first reported case of pulmonary BALT lymphoma coexistent with pulmonary tuberculosis.  相似文献   
254.
The Epstein-Barr virus (EBV) has been shown to be associated with numerous human malignancies including Burktt's lymphoma and nasopharyngeal lymphoepithelioma. In addition, some typical gastric adenocarcinomas were also recently reported to demonstrate EBV relevance. The present study was designed to detect EBV in primary gastric lymphoma, using the in situ hybridization (ISH) method, in which oligo-nucleotide probes for the EBERl RNA and the EBV DNA W region have been used. Of the 49 cases of primary gastric lymphoma studied, which all showed B cell immunopheno-type, EBER1 sequences could only be found in four cases, including two low-grade cases and two high-grade cases of histological subtypes while the number of positive cells was less than 50% of the tumor cells. In one case of low-grade mucosa associated lymphoid tissue (MALT) lymphoma, the EBER1 -positive neoplastic cells were found in the regional lymph node, but the primary site of the stomach showed no positive signals. The EBV presence was further confirmed by the EBV DNA ISH. Using the ISH method, rare or occasional positive lymphoid cells (probably non-tumorous bystander cells) could be detected in 10 other cases including all histological subtypes. The present study shows that only a small proportion of primary gastric lymphoma is associated with EBV, and such positive cases could be found in both high- and low-grade histological subtypes. It is also suggested that the EBV presence in the neoplastic cells of some cases of primary gastric lymphoma is most likely a secondary phenomenon.  相似文献   
255.
本文报道一例用病理组织学、免疫组织化学和免疫电镜综合确诊的多克隆性IBL样T细胞性淋巴瘤。讨论了这三种病理研究手段综合应用在本例诊断中的意义。指出免疫电镜在确定阳性反应细胞的细微形态上较光镜有明显优越性。  相似文献   
256.
目的:探讨我国沈阳地区非何杰金淋巴瘤(NHL)的病理特点及免疫组化表型分析。方法:对76例NHL按照WHO新分类进行病理观察和10种抗体免疫表型测定。结果:B系占78.9%,其中弥漫性大B细胞淋巴瘤(DLBL)最多;其次为MALT型(+/-单核细胞样B细胞)及淋巴浆细胞性淋巴瘤(LPL)。T系占21.1%,以外周T非特殊型最多。CD79a对B-NHL染色阳性率达100%,未见与T细胞的交叉反应。CD3对T-NHL染色阳性率为88%,与B细胞仅有5%的交叉反应。结论:我国沈阳地区NHL以DLBL和外周T非特殊型为最多见,结内单核B和淋巴浆细胞性比例较高。CD79a和CD3分别是具有高度敏感性和特异性的B、T细胞标志抗体。  相似文献   
257.
165例恶性淋巴瘤中p16基因异常的研究   总被引:3,自引:0,他引:3  
目的 检测恶性淋巴瘤(ML)中p16基因的缺失、甲基化及p16蛋白的表达,探讨p16基因异常在淋巴瘤中的意义。方法 收集淋巴瘤鹇组织标本50例,存档石蜡包埋组织标本115例,均包括T、B非霍奇金淋巴瘤(NHL)及霍奇金淋巴瘤(HL)。用PCR、甲基化特异的PCR方法检测新鲜组织中的p16基因的等位缺失及5‘CgG岛异常甲基化;用免疫组织化学方法检测石蜡标本中p16蛋白的表达情况。另外,分别选取9例反应性增生(RH)组织的标本作对照。结果 12/50例(24.0%)新鲜标本中检出p16基因纯合性缺失,16/50例(32.0%)检出p16基因异常高甲基化;石蜡包埋标本中p16蛋白的失表达率为41.6%,其中B-NHL为46.0%,T-NHL为54.5%,HL为31.6%。恶性程度较高的淋巴瘤类型中p16蛋白的失表达率也相应较高,各类型之间比较:弥漫性大B细胞淋巴瘤(DLBCL)和滤泡性淋巴瘤(FL)的p16失表达率存在组间差异的显著性。所有RH标本均未见p16基因或蛋白表达的异常。结论 恶性淋巴瘤中p16基因的异常是一个频发事件,p16基因表达异常参与了淋巴瘤的发生及进展。  相似文献   
258.
259.
ObjectivesT-cell-mediated adaptive immunity contributes to the development and persistence of ankylosing spondylitis (AS). Mesenchymal stromal/stem cells (MSCs) have immunomodulatory potential and are able to inhibit T-cell proliferation, but their functionality in AS patients is relatively unknown. The aim of the study was to assess the direct anti-proliferative effects of MSCs isolated from subcutaneous abdominal adipose tissue of AS patients (AS/ASCs) on allogeneic T lymphocytes, using commercially available ASC lines from healthy donors (HD/ASCs) as a control.Material and methodsCD3+CD4+ T-cells were isolated from peripheral blood of healthy blood donors, activated with anti-CD3/CD28 beads, and co-cultured for 5 days with untreated and TNF+IFN-γ pre-stimulated HD/ASCs (5 cell lines) and AS/ASCs, obtained from 11 patients (6F/5M). The proliferative response of T-cells was analysed by flow cytometry, while the concentrations of kynurenines, prostaglandin E2 (PGE-2), interleukin 10 (IL-10), and interleukin 1 receptor antagonist (IL-1Ra) were measured spectrophotometrically or using a specific enzyme-linked immunosorbent assay (ELISA).ResultsHD/ASCs and AS/ASCs similarly reduced the T-cell proliferation response, i.e. the percentage of proliferating cells, the proliferation, and replication indices, and these effects were dependent mostly on soluble factors. In the co-cultures of activated CD4+ T-cells with HD/ASCs and AS/ASCs significant increases of kynurenines, PGE-2, and IL-1Ra, but not IL-10, production were observed. The release of these factors was dependent either on cell-to-cell contact (IL-10, IL-1Ra) or soluble factors (kynurenines, PGE-2). There was a moderate to strong negative correlation between T-cell proliferative response, and the concentrations of kynurenines, PGE-2, and IL-10, but not IL-1Ra. This association was more evident in the case of TI-treated AS/ASCs than HD/ASCs.ConclusionsAS/ASCs, similar to HD/ASCs, exert a direct effective anti-proliferative impact on CD4+ T cells, acting via soluble factors that are released in cell contact-dependent (IL-10) and independent (kynurenines, PGE-2) pathways. Thus, our results suggest that AS/ASCs are potentially useful for therapeutic application.  相似文献   
260.
目的 探讨胃肠道淋巴瘤并发急性穿孔的临床病理特征及预后影像因素。方法 回顾性分析2013年1月至2020年12月复旦大学附属中山医院收治的因胃肠道淋巴瘤并发急性穿孔行急诊手术的36例病人的临床资料。分析其临床病理特征、术后死亡情况以及死亡相关风险因素。结果 36例病人中32例(88.9%)为小肠淋巴瘤穿孔。所有病人均为非霍奇金淋巴瘤,且以侵袭性病理类型多见,其中单形性嗜上皮性肠道T细胞淋巴瘤[44.4%(16/36)]和弥漫性大B细胞淋巴瘤[33.3%(12/36)]为最常见的两种病理亚型。术后共11例病人(30.6%,11/36)发生死亡,其中10例为术后即转入重症监护室(ICU)的病人。在转入ICU的29例重症病人中,发生死亡者术后动脉血乳酸水平(P=0.006)及序贯器官衰竭(SOFA)评分(P=0.016)均高于生存者,而其他指标差异均无统计学意义(P>0.05)。结论 淋巴瘤引起的消化道急性穿孔多发生于小肠,术后病死率高;较高的SOFA评分及动脉血乳酸水平可能是死亡相关危险因素。  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