全文获取类型
收费全文 | 5702篇 |
免费 | 680篇 |
国内免费 | 170篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 47篇 |
妇产科学 | 179篇 |
基础医学 | 2212篇 |
口腔科学 | 60篇 |
临床医学 | 424篇 |
内科学 | 424篇 |
皮肤病学 | 24篇 |
神经病学 | 80篇 |
特种医学 | 53篇 |
外国民族医学 | 4篇 |
外科学 | 338篇 |
综合类 | 832篇 |
预防医学 | 306篇 |
眼科学 | 167篇 |
药学 | 216篇 |
中国医学 | 54篇 |
肿瘤学 | 1081篇 |
出版年
2024年 | 13篇 |
2023年 | 51篇 |
2022年 | 93篇 |
2021年 | 176篇 |
2020年 | 197篇 |
2019年 | 235篇 |
2018年 | 167篇 |
2017年 | 229篇 |
2016年 | 252篇 |
2015年 | 244篇 |
2014年 | 377篇 |
2013年 | 369篇 |
2012年 | 363篇 |
2011年 | 393篇 |
2010年 | 315篇 |
2009年 | 323篇 |
2008年 | 277篇 |
2007年 | 290篇 |
2006年 | 261篇 |
2005年 | 216篇 |
2004年 | 214篇 |
2003年 | 177篇 |
2002年 | 181篇 |
2001年 | 132篇 |
2000年 | 54篇 |
1999年 | 65篇 |
1998年 | 147篇 |
1997年 | 117篇 |
1996年 | 91篇 |
1995年 | 56篇 |
1994年 | 42篇 |
1993年 | 51篇 |
1992年 | 38篇 |
1991年 | 41篇 |
1990年 | 35篇 |
1989年 | 33篇 |
1988年 | 39篇 |
1987年 | 40篇 |
1986年 | 38篇 |
1985年 | 34篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 14篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 4篇 |
排序方式: 共有6552条查询结果,搜索用时 15 毫秒
1.
花生四烯酸和二十二碳六烯酸对海马神经细胞生长发育的影响 总被引:2,自引:0,他引:2
【目的】观察不同浓度花生四烯酸 (AA)和 (或 )二十二碳六烯酸 (DHA)对体外培养海马神经细胞生长发育的影响。【方法】无血清培养液中分别加入不同剂量的AA和 (或 )DHA ,采用噻唑蓝比色试验 (MTT法 )反映各组海马神经细胞存活状况 ,神经元特异性烯醇化酶 (NSE)染色鉴定神经细胞 ,图像分析技术测量神经细胞的胞体大小和突起长度。【结果】培养液中分别添加AA为 4~ 8μmol/L、DHA为 2~ 8μmol/L时 ,神经细胞活力高于对照组 ;当培养液中AA和DHA总浓度为 4μmol/L、比例为 2∶1或 4∶1时 ,神经细胞的活力、胞体面积、最大长径、最大短径和平均突起长度均显著高于单一添加 4μmol/LAA、4μmol/LDHA和对照组。【结论】AA、DHA均具有促进体外培养海马神经细胞生长发育的作用 ;与单独添加AA、DHA相比 ,AA和DHA共同作用的促海马神经细胞生长发育作用更好。 相似文献
2.
Hideya Ohnishi Kazuyoshi Nishihara Keiyoshi Tamae Shoshu Mitsuyama Ryuji Abe Satoshi Toyoshima Eiji Abe 《Surgery today》1996,26(11):929-932
Granular cell tumors (GCT) are rare neoplasms, and only 173 cases of benign GCT of the breast have been documented. We report herein the cases of two patients with this tumor and discuss the methods of diagnosis and treatment. The first patient was a 60-year-old woman who presented with a firm ill-defined mass in her left breast. Mammography showed a dense shadow with spicula and skin thickness, and ultrasonography revealed a hypoechoic mass with an irregular border. Radical mastectomy was performed under the wrong preoperative diagnosis of breast cancer. The second patient was a 31-year-old woman who presented with an elastic-hard mass in her left breast. Mammography showed a well-demarcated dense mass, and ultrasonography revealed a well-defined hypoechoic mass with a large depth-width ratio. Fine-needle aspiration cytology (FNAC) showed a large number of histiocytic cells with abundant granular cytoplasm. An excisional biopsy was performed, and histological examination confirmed a diagnosis of GCT. GCT is benign, but often misdiagnosed as breast cancer both clinically and radiologically. Therefore, histological examination is essential for making a correct diagnosis, while FNAC is also useful. Local resection is still the treatment of choice, and surgeons should do their utmost to avoid performing needless radical mastectomy. 相似文献
3.
兔关节软骨细胞的分离、培养和形态学特征 总被引:9,自引:2,他引:7
[目的]探讨兔关节软骨细胞的分离、培养方法,观察单层高浓度培养时细胞表型表达情况.[方法]无菌条件下,从 2周龄新西兰白兔的颞颌关节及四肢关节髁突面削取软骨片,采用机械-酶消化法分离软骨细胞,经台盼蓝拒染计数,将细胞按 1× 106个 /孔接种于 6孔培养板,传代培养,描绘生长曲线.利用相差显微镜及透射电镜观察细胞形态.应用甲苯胺蓝及Ⅱ型胶原免疫组化对细胞进行鉴定.[结果]每克软骨能获取 1 5× 106个软骨细胞,活性率为 95%.培养 2~ 3 d,细胞贴壁、变形,呈多角形; 8 d左右,细胞融合成层.透射电镜观察显示细胞核圆形,有丰富的粗面内质网、高尔基体及分泌的基质成分.甲苯胺蓝及Ⅱ型胶原染色阳性.细胞传至 5代后,出现"成纤维细胞样".[结论]本研究建立了简单易行的软骨细胞分离、培养方法;初代、第 2代细胞生长良好,适合于实验研究;软骨细胞 5代培养后,细胞表型发生改变. 相似文献
4.
J. M. Porcher C. Lafuma R. El Nabout M. P. Jacob P. Sébastien P. A. Borm S. Honnons G. Auburtin 《International archives of occupational and environmental health》1993,65(Z1):S209-S213
This research is designed to evaluate a number of biological markers to estimate harmful exposure on coal miners from different mining regions in France and to relate the outcome to differences in prevalence of coal worker pneumoconiosis (CWP) between these regions. Eight epidemiological groups of active and ex-miners (smokers and non-smokers) have been selected in the French collieries (North, Lorraine and Provence) according to their occupational and pneumoconiotic status. The following biomarkers have been evaluated: cellularity of sputum, elementary analysis of particles in TEM/EDAX, plasma neutral metalloendo peptidase elastase type (NMEP), leucocyte elastase (HLE), fibronectin (FN) and elastin peptides. Pulmonary alveolitis, expressed by sputum cellularity, is different between active workers groups but not related to the general background of pneumoconiosis prevalence in the French collieries. In the plasma parameters, fibronectin, HLE and NMEP significantly increased in all groups of coal mine workers as compared to the control group, except for fibronectin parameter in Lorraine collierie. The degree of increase of these parameters allow us to discriminate the different groups and suggest that plasma FN, HLE and NMEP may be considered as biological markers of chronic inhalation of coal mine dust particles. The decrease of elastin peptides level in the Lorraine group alone suggests a specific alteration of elastin metabolism. These parameters were not related to the development of pneumoconiosis and its degree of severity. 相似文献
5.
The diagnostic yield of cytology in histologically proven transitional-cell carcinoma (TCC) of the urinary bladder has been studied in 100 cases. Cytohistologic correlation rates were 20 percent, 61.7 percent, and 92.8 percent, respectively, for grade 1, 2, and 3 tumors. When further evaluated, G2 cases were segregated into 2 subcategories, G2a and G2b, based on histologic preservation of nuclear polarity, pleomorphism, and other cellular irregularities. Correlation rates were rather low for G2a cases (6/18, 33%) and high for G2b cases, (23/29; 79%). The prevalence of atypical cells was 2 (11.1%) cases in G2a and 16 (55.2%) cases in G2b. The results of this study confirm that cytology has an extremely varying diagnostic yield in urinary bladder TCC. Greater cell exfoliation, increased atypia, and a tendency to infiltration of G2b and G3 cases probably account for the higher diagnostic yield detected in these groups. 相似文献
6.
Endoscopic ultrasound (EUS) is sensitive for staging gastrointestinal malignancies and pancreatic lesions. EUS‐fine‐needle aspiration (EUS‐FNA) offers a diagnostic accuracy of about 60–90% for pancreatic tumors and > 90% for lymph nodes. There are several limitations of EUS‐FNA including the need for on‐site cytopathology review. In addition, accuracy of cytologic review is hampered by the presence of blood, benign epithelial cells, desmoplasia, and well‐differentiated tumors. Furthermore, the small biopsy sample and destruction of tissue architecture limits the diagnostic sensitivity for GISTs and lymphomas. Many of these problems can be overcome with use of EUS trucut biopsy (TCB) needles. These large caliber, cutting needles acquire larger tissue samples allowing preservation of tissue architecture and histologic examination. Our recently described experience with EUS‐TCB initially in swine and later humans demonstrated the safety for acquiring histologic tissue representative of the target organs sampled enabling accurate diagnosis. These studies suggested greater diagnostic accuracy of EUS‐TCB for submucosal mass lesions and lymphoma and potentially the need for fewer needle passes for solid pancreatic neoplasms. In this paper we will review the current TCB literature, device design and technique, help troubleshoot potential problems, and offer opinion as to the utility and role of this new device. 相似文献
7.
K Alderson 《Muscle & nerve》1992,15(11):1284-1289
The presence, morphology, distribution, and abundance of axonal swellings in intramuscular nerves were evaluated. Axonal swellings were present in intramuscular nerves in 42% of 127 muscle biopsies from patients with a variety of conditions. The incidence was highest in muscle from patients with peripheral neuropathy, but swellings were present in muscle from patients with motor neuron disease, primary muscle diseases, and some individuals without clinical or histological evidence of neuromuscular disease. The greatest number of swellings in intramuscular nerves was in muscle from patients with chronic inflammatory demyelinating neuropathy. Swellings were spherical or elliptical, 4-20 microns in diameter, 5-30 microns in length, and composed of neurofilaments. Swellings were present only in myelinated axons of intramuscular nerves, proximal to nodes of Ranvier or in internodal regions. Swellings were not associated with axonal degeneration. They were probably not transported. The formation or accumulation of swellings may reflect altered axonal dynamics common to a number of disease processes. 相似文献
8.
慢性阻塞性肺疾病的肺生物学标记物研究进展 总被引:1,自引:1,他引:0
与慢性阻塞性肺疾病(COPD)有关的很多炎症细胞、介质,正逐渐为人们所熟知。本文讨论支气管活组织切片、痰液、支气管肺泡灌洗液、呼出气凝物等方面的有关生物标记在COPD研究中的进展。 相似文献
9.
Granulocytic sarcoma (GS) is a localized tumour of immature granulocytes that is usually associated with myelogenous leukaemia. We report an unusual case of mastoid GS with meningeal extension but no bone marrow involvement on presentation. Histological examination of the surgical specimen and the characteristic cerebrospinal fluid (CSF) cytology showing cytoplasmic granulations and Auer bodies led to the diagnosis of GS. Positive cytochemical staining of the immature CSF cells for naphtol-ASD chloroacetate esterase and myeloperoxidase confirmed their myeloid origin. Immunophenotyping did not reveal common acute lymphoblastic leukaemia antigen, cytokeratin, T or B-cell antigens. The patient underwent surgical resection of the localized tumour, followed by radiation therapy, intrathecal and systemic chemotherapy, as if he had acute myelogenous leukaemia (AML). He did not develop AML in the 21 months after the tumour resection. This case emphasizes the value of CSF cytological examination of tumour cells and the use of an immumocytochemical marker for differentiating GS from malignant lymphoma. 相似文献
10.
Clear-cell lesions of the parotid gland are uncommon but when studied by fine-needle aspiration may result in a clinically important but cytologically difficult differential diagnosis. Clear-cell lesions involving the parotid include acinic cell neoplasm, clear cell oncocytoma, mucoepidermoid carcinoma, primary clear-cell carcinoma, epithelial-myoepithelial carcinoma, and metastatic renal cell carcinoma. Accurate diagnosis is achieved by assessment of nuclear features, other cell populations present, and clinical data including radiographic studies. 相似文献