全文获取类型
收费全文 | 93790篇 |
免费 | 9309篇 |
国内免费 | 4729篇 |
专业分类
耳鼻咽喉 | 2596篇 |
儿科学 | 386篇 |
妇产科学 | 1707篇 |
基础医学 | 10660篇 |
口腔科学 | 3400篇 |
临床医学 | 6707篇 |
内科学 | 11598篇 |
皮肤病学 | 1976篇 |
神经病学 | 218篇 |
特种医学 | 4286篇 |
外国民族医学 | 122篇 |
外科学 | 13758篇 |
综合类 | 16532篇 |
现状与发展 | 23篇 |
预防医学 | 2026篇 |
眼科学 | 396篇 |
药学 | 4622篇 |
14篇 | |
中国医学 | 1135篇 |
肿瘤学 | 25666篇 |
出版年
2024年 | 103篇 |
2023年 | 1277篇 |
2022年 | 1979篇 |
2021年 | 3607篇 |
2020年 | 3152篇 |
2019年 | 2997篇 |
2018年 | 2865篇 |
2017年 | 3275篇 |
2016年 | 3701篇 |
2015年 | 4227篇 |
2014年 | 6217篇 |
2013年 | 5459篇 |
2012年 | 5652篇 |
2011年 | 6124篇 |
2010年 | 4988篇 |
2009年 | 4925篇 |
2008年 | 5119篇 |
2007年 | 5427篇 |
2006年 | 5071篇 |
2005年 | 4529篇 |
2004年 | 3577篇 |
2003年 | 3139篇 |
2002年 | 2680篇 |
2001年 | 2580篇 |
2000年 | 2187篇 |
1999年 | 1754篇 |
1998年 | 1596篇 |
1997年 | 1430篇 |
1996年 | 1258篇 |
1995年 | 1068篇 |
1994年 | 978篇 |
1993年 | 678篇 |
1992年 | 594篇 |
1991年 | 517篇 |
1990年 | 437篇 |
1989年 | 380篇 |
1988年 | 363篇 |
1987年 | 291篇 |
1986年 | 240篇 |
1985年 | 260篇 |
1984年 | 212篇 |
1983年 | 151篇 |
1982年 | 172篇 |
1981年 | 147篇 |
1980年 | 136篇 |
1979年 | 109篇 |
1978年 | 76篇 |
1977年 | 53篇 |
1976年 | 45篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
991.
Kazutoshi Ono Yoshiyuki Yamanaga Kyousuke Yamamoto Shun-Ichi Koga Junji Nishimura Hajime Nawata 《Journal of clinical immunology》1996,16(1):41-45
Previously we proposed a new analysis of natural killing activity, for comparison, employing an individual effector/ target cell ratio according to the peripheral number of effector cells. Using this analysis, we studied natural killing activities in chronic liver diseases and hepatocellular carcinoma (HCC). The activity in chronic persistent hepatitis remained nearly at the level of the nonactivated state, but that was significantly elevated in chronic active hepatitis. The activity in liver cirrhosis (LC) of Child's A or B grade was at the level of a nonactivated or reduced-activity state, while LC patients with impaired general conditions showed significantly elevated activities. In HCC, each of which was accompanied by LC in our cases, the activity appeared to be associated with the progression of HCC. Thus, natural killing activity showed a close relationship with the condition of chronic liver diseases. 相似文献
992.
Fine-needle aspiration biopsy findings in three cases of chromophobe cell carcinoma are described and correlated with histologic and ultrastructural observations. In addition, comparisons are made with three cases each of oncocytoma and granular cell carcinoma. The cells in aspiration smears from chromophobe cell carcinoma closely correlated with histologic pattern of three cell types which were not present in oncocytomas and granular cell carcinomas. These cells had prominent cell borders, and their cytoplasm was either opaque and granular (type I) or variably translucent and reticular (type II and III). Ultrastructurally, the translucent areas within the cytoplasm contained large numbers of microvesicles which were unique to chromophobe cell carcinoma and were not seen in other neoplasms. Fine-needle aspiration may be used to diagnose chromophobe cell carcinoma and distinguish it from other related renal neoplasms. © 1995 Wiley-Liss, Inc. 相似文献
993.
A case of mixed medullary follicular carcinoma of the thyroid is reported. Grossly, the tumor was a solid, grayish white, well circumscribed mass without lymph node metastasis. Microscopically, the tumor showed both medullary and follicular areas. The follicular areas occupied discrete portions of the tumor, and were considered to be neoplastic. Tumor cells in the medullary area were polyhedral or spindle-shaped. There was no amyloid deposition within the tumor. Immunohistochemically, tumor cells in the medullary area were positive for calcitonin and negative for thyroglobulin. Some cells lining the follicles were positive for thyroglobulin. By electron microscopy, two types of tumor cell were observed. One type contained numerous cytoplasmic secretory granules, whereas the other type had few granules and showed a prominent rough endoplasmic reticulum. These findings suggested that this mixed medullary follicular carcinoma of the thyroid presented neoplastic changes within a common cell lineage. 相似文献
994.
Takatsugu Yamamoto Takashi Ikebe Shinichi Mikami Taichi Shuto Kazuhiro Hirohashi Hiroaki Kinoshita Masaml Sakurai 《Pathology international》1996,46(5):364-371
The sinusoidal structure and blood supply of 38 liver nodules less than 2 cm In diameter were Investigated. There were 18 cases of adenomatous hyperplasia (AH) and 20 cases of hepatocetlular carcinoma (HCC). Growth pattern, encapsulation and vascularity were examined, and Immunohistochemistry performed for factor VIII related antigen (factor VIII), type IV collagen (collagen IV), lamlnln and CD68. There were significant differences between AH and small HCC, except for the expression of CD68. There were differences In tumor size, vasculartty and the components of the basement membrane between AH and small, well differentiated HCC. The cases of AH were supplied by the portal system and maintained the sinusoidal structure, but small well-differentiated HCC were supplied by a mixture of portal and arterial vessels. In spite of their small size, moderately and poorly differentiated HCC had capillary and were supplied by branches of the hepatic artery. 相似文献
995.
Jakob CA Guldenschuh I Hürlimann R Müllhaupt B Müller A Ammann R Fried M Roth J 《Virchows Archiv : an international journal of pathology》1999,434(1):57-62
DNA methylation plays an important part in the regulation of gene expression. Alterations in DNA methylation in tumours have
been reported and have been used to generate hypotheses about mutagenesis and silencing of tumour suppressor genes. However,
the underlying mechanism is still poorly understood, and conflicting data on the levels of overexpression of 5′-cytosine DNA
methyltransferase in sporadic colon carcinoma have been published. We used a competitive RT-PCR assay for quantification of
mRNA of 5′-cytosine DNA methyltransferase in colon biopsies obtained from patients with hereditary colon carcinoma syndromes
and compared the results with those obtained in a control group. No significant difference was found between the flat mucosa
of FAP patients and the mucosa of the control group. In FAP and HNPCC patients, the 5′-cytosine DNA methyltransferase mRNA
levels of adenomas were significantly higher (P<0.05) than of flat mucosa in the same group, but both showed great variability from patient to patient. Our findings suggest
that the mRNA levels of methyltransferase cannot be used as predictive marker for screening in families affected by hereditary
colon carcinoma.
Received: 20 July 1998 / Accepted: 21 September 1998 相似文献
996.
目的 探讨热休克蛋白 70 (HSP70 )在肝细胞癌 (HCC)中的表达及其意义。方法 采用免疫组化技术对 4 4例HCC和癌旁组织中HSP70的表达进行检测。结果 HCC中HSP70阳性率明显高于癌旁组织 (阳性率分别为 6 8.2 %和2 7.3% ,χ2 =7.3,P <0 .0 1)。HSP70表达与癌周淋巴细胞浸润 (χ2 =3.2 ,P >0 .0 5 )和转移 (χ2 =2 .3,P >0 .0 5 )无关 ,但与癌组织分化程度有关 (χ2 =4 .5 ,P <0 .0 5 )。结论 HSP70的异常表达与HCC的发生、发展有关 ,且可能是HCC发展、恶化的重要标志 相似文献
997.
Leroy X Wacrenier A De la Taille A Gosset P Saint F Biserte J Gosselin B 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2001,109(6):469-473
Sarcomatoid renal cell carcinomas (SRC) are rare neoplasms associated with a very poor prognosis. The aim of this study was to evaluate biomarker expression and clinical significance in this uncommon renal cancer. Cytokeratin, epithelial membrane antigen, vimentin, desmin, smooth muscle actin, CD34, S-100 protein, MIB 1, p53, Fas and Fas ligand immunohistochemical expression was investigated in seven renal cell carcinomas with sarcomatoid changes. No significant difference between sarcomatoid and nonsarcomatoid areas was observed with the different biomarkers, excepted for Fas ligand. Fas expression was diffuse in sarcomatoid and nonsarcomatoid areas. However, Fas ligand had a higher expression in sarcomatoid in comparison to nonsarcomatoid areas. Our results showed that Fas and Fas ligand are both expressed in renal cancer. We suggest that the aggressive behavior of sarcomatoid carcinoma may be related to a higher expression of Fas ligand by tumor sarcomatoid cells. These findings may indicate that Fas ligand is a possible therapeutic molecular target for treatment of SRC. 相似文献
998.
We report on a case of invasive lobular carcinoma of the breast with a previously undescribed cytologic feature. Diff-Quik-stained cytologic preparations showed uniform single cells with prominent coarse cytoplasmic granules. Ultrastructurally, the granules showed features suggestive of autophagosomes and/or degenerative mitochondria. The cytologic differential diagnosis included granulocytic sarcoma, metastatic melanoma, extramedullary hematopoiesis, large granulocytic leukemia/lymphoma, and mast-cell tumor. Adjunctive studies were helpful in the diagnosis of carcinoma. Histologic study of the mastectomy specimen showed classic type of invasive lobular carcinoma. 相似文献
999.
目的探讨非小细胞肺癌(non-sm all cell lung cancer,NSCLC))急慢性乏氧状况、乏氧与COX-2过度表达及与临床病理特征的关系。方法应用兔抗人H IF-1α、GLUT1抗体和鼠抗人COX-2抗体对手术切除的46例肺癌组织进行免疫组化染色,并与临床病理资料进行相关性分析。结果肺癌患者46例,其中ⅠA期12例,ⅠB期20例,Ⅱ期8例,ⅢA期6例。H IF-1α、GLUT1和COX-2的阳性表达率分别为58.70%(27/46)、39.11%(18/46)和67.39%(31/46)。COX-2表达与H IF-1α、GLUT1的表达相关(P<0.01)。GLUT1表达与肺癌患者淋巴结转移(P<0.05)、组织学类型(P<0.01)有关,而H IF-1α、COX-2表达与年龄、性别、分期、肿瘤大小、淋巴结转移、组织学类型和肿瘤分化程度均无相关性。结论NSCLC患者同时存在着急、慢性乏氧,而肿瘤转移主要与慢性乏氧有关。另外,乏氧可能参与了COX-2增强表达的机制。 相似文献
1000.
乳腺微浸润癌的临床病理学特征及生物学特性 总被引:1,自引:0,他引:1
目的探讨乳腺微浸润癌(microinvasive carcinoma,MIC)的临床病理学特征及生物学特性和其病理诊断标准。方法回顾性研究40例MIC,按文献报道诊断标准分为两个亚型,并对病理学特征、分子生物学指标及预后进行比较。结果MIC占同期乳腺癌的1.5%,乳腺钼靶拍片85.0%的病例(34例/40例)显示不同程度的泥沙样钙化。粉刺型和高核分级的导管内癌更易形成间质浸润。淋巴结转移2.5%(1例/40例)。31例平均8个月随访显示无复发及转移。两亚型各指标比较结果差异均无显著性。结论MIC是一种少见、淋巴结转移率低、预后较好的恶性肿瘤。建议诊断标准:单个浸润灶时,最大径应〈2mm;出现几个浸润灶时,其中单个浸润灶的最大径应〈1mm,且几个浸润灶面积总和不应超过整个肿瘤组织面积的10%。 相似文献