全文获取类型
收费全文 | 6042篇 |
免费 | 587篇 |
国内免费 | 316篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 114篇 |
妇产科学 | 114篇 |
基础医学 | 774篇 |
口腔科学 | 133篇 |
临床医学 | 780篇 |
内科学 | 999篇 |
皮肤病学 | 91篇 |
神经病学 | 342篇 |
特种医学 | 234篇 |
外科学 | 760篇 |
综合类 | 868篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 334篇 |
眼科学 | 139篇 |
药学 | 537篇 |
2篇 | |
中国医学 | 256篇 |
肿瘤学 | 430篇 |
出版年
2024年 | 20篇 |
2023年 | 96篇 |
2022年 | 160篇 |
2021年 | 335篇 |
2020年 | 254篇 |
2019年 | 188篇 |
2018年 | 250篇 |
2017年 | 198篇 |
2016年 | 193篇 |
2015年 | 254篇 |
2014年 | 318篇 |
2013年 | 283篇 |
2012年 | 439篇 |
2011年 | 484篇 |
2010年 | 266篇 |
2009年 | 248篇 |
2008年 | 319篇 |
2007年 | 310篇 |
2006年 | 276篇 |
2005年 | 282篇 |
2004年 | 228篇 |
2003年 | 205篇 |
2002年 | 160篇 |
2001年 | 150篇 |
2000年 | 145篇 |
1999年 | 157篇 |
1998年 | 96篇 |
1997年 | 84篇 |
1996年 | 76篇 |
1995年 | 65篇 |
1994年 | 51篇 |
1993年 | 37篇 |
1992年 | 49篇 |
1991年 | 38篇 |
1990年 | 39篇 |
1989年 | 29篇 |
1988年 | 23篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1979年 | 10篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 6篇 |
1969年 | 6篇 |
排序方式: 共有6945条查询结果,搜索用时 15 毫秒
41.
间变性大细胞淋巴瘤形态学及免疫表型观察 总被引:1,自引:1,他引:1
目的:探讨间变性大细胞淋巴瘤(ALCL)的形态学和免疫表型特征。方法:对6例ALCL和2例弥温性大B细胞淋巴瘤(DLBCL)进行形态学和免疫组织化学染色(ABC法)观察。结果:6例ALCL中,普通型2例、淋巴组织细胞型2例、ALK-变型2例,均可见单型性或多形性的标志性大细胞。普通型和ALK-变型大细胞沿淋巴窦内生长,而淋巴组织细胞型大细胞则呈散在分布;2例DLBCL形态上颇似ALCL;6例ALCL均为T细胞,CD30+,儿童患者共同表达ALK+和EMA+,年长者则ALK-和EMA-。2例DLBCL均为B细胞,ALK+、CD30-和EMA-。结论:不论何型ALCL,均可见CD30+的标志性大细胞,淋巴窦内生长多见于普通型和ALK-变型。ALCK均为T细胞,儿童常有ALK和EMA共同表达,年长者则ALK和EMA-。DLBCL的免疫表型不同于ALCL。 相似文献
42.
The increased incidence of thyroid carcinomas in familial adenomatous polyposis (FAP) patients is well recognised. These thyroid neoplasms display distinctive clinicopathological features and generally show good prognostic outcome. Recently, unusual sporadic tumours that share the morphological features of FAP-associated thyroid carcinomas have also been described. In this report, we document a case of a thyroid tumour in a previously well, 46-year-old female. Histology revealed a circumscribed neoplasm composed of tubular, papillary, cribriform and solid areas. The pseudostratified columnar tumour cells showed occasional nuclear grooves and rare nuclear inclusions. Immunohistochemistry showed positive staining with antibodies to cytokeratin AE1/AE3, oestrogen and progesterone receptor proteins. Focal immunoreactivity was also noted with antibodies to thyroglobulin, epithelial membrane antigen, 34betaE12 and cytokeratin CK7. The absence of polyps on colonoscopy and germline mutation in the adenomatous polyposis coli (APC) gene provides evidence that this tumour represents the sporadic counterpart of FAP-associated thyroid carcinoma. The patient is well with no evidence of disease 7 months following resection of the tumour. The differential diagnoses and molecular genetics of this unusual tumour are discussed. 相似文献
43.
44.
编制并初步应用大学生独立倾向与独立能力问卷。访谈29名大学生,编制初测问卷;以150份样本进行预测验;采用625份样本进行问卷信效度检验,形成最终问卷;以493份样本进行问卷初步应用。结果显示:①独立倾向分为自主性和掌控感2个维度共6个项目;独立能力分为领导能力、自律能力、规划能力3个维度共12个项目。独立倾向与独立能力及其各维度的内部一致性信度系数在0.703~0.738之间;6周后的重测信度分别为0.719和0.753;问卷的结构效度良好;独立倾向/独立能力与基本心理需求满足的各维度呈正相关。②大学生的独立倾向显著高于独立能力;聚类分析可将大学生根据其独立倾向与独立能力分为3类:完成型、延缓型、矛盾型。大学生独立倾向与独立能力问卷的信效度良好。 相似文献
45.
Susan L. Swain Javed N. Agrewala Deborah M. Brown Dawn M. Jelley-Gibbs Susanne Golech Gail Huston Stephen C. Jones Cris Kamperschroer Won-Ha Lee K. Kai McKinstry Eulogia Román Tara Strutt Nan-ping Weng 《Immunological reviews》2006,211(1):8-22
Summary: We have outlined the carefully orchestrated process of CD4+ T‐cell differentiation from naïve to effector and from effector to memory cells with a focus on how these processes can be studied in vivo in responses to pathogen infection. We emphasize that the regulatory factors that determine the quality and quantity of the effector and memory cells generated include (i) the antigen dose during the initial T‐cell interaction with antigen‐presenting cells; (ii) the dose and duration of repeated interactions; and (iii) the milieu of inflammatory and growth cytokines that responding CD4+ T cells encounter. We suggest that heterogeneity in these regulatory factors leads to the generation of a spectrum of effectors with different functional attributes. Furthermore, we suggest that it is the presence of effectors at different stages along a pathway of progressive linear differentiation that leads to a related spectrum of memory cells. Our studies particularly highlight the multifaceted roles of CD4+ effector and memory T cells in protective responses to influenza infection and support the concept that efficient priming of CD4+ T cells that react to shared influenza proteins could contribute greatly to vaccine strategies for influenza. 相似文献
46.
Tales of tails: regulation of telomere length and telomerase activity during lymphocyte development, differentiation, activation, and aging 总被引:13,自引:0,他引:13
Nan-ping Weng Larry D. Palmer Bruce L Levine H. Clifford Lane Carl H. June Richard J. Hodes 《Immunological reviews》1997,160(1):43-54
Summary: Telomerase activity and the regulation of telomere length are factors which have been implicated in the control of cellular replication. These variables have been examined during human lymphocyte development, differentiation, activation, and aging. It was found that telomere length of peripheral blood CD4+ T cells decreases with age as well as with differentiation from naive to memory cells in vivo , and decreases with cell division in vitro. These results provide evidence that telomere length correlates with lymphocyte replicative history and residual replicative potential. In contrast, telomere length appears to increase during tonsil B-cell differentiation and germinal center (GC) formation in vivo. It was also found that telomerase activity is highly regulated during T-cell development and B-cell differentiation in vivo , with high levels of telomerase activity expressed in thymocytes and GC B cells, and low levels of telomerase activity in resting mature peripheral blood lymphocytes. Finally, resting lymphocytes retain the ability to upregulate telomerase activity upon activation, and this capacity does not appear to decline with age. Although the precise role of telomerase in lymphocyte function remains to be elucidated, telomerase may contribute to protection from telomere shortening in T and B lymphocytes, and may thus play a critical role in lymphocyte development, differentiation and activation. The future study of study telomerase and its regulation of telomere length may enhance our understanding of bow the replicative lifespan is regulated in lymphocytes. 相似文献
47.
北京地区精神分裂症患者家属情感表达测查报告 总被引:10,自引:2,他引:10
目的;探讨北京地区的住院精神分裂症患者家属情感表达方式及测查方法的实用性、测查工具应用的一致性。方法:经过训练的研究人员,采用费氏修订的CFI-CV访谈提纲,对171例住院精神分裂症患者家庭的284位家属进行访谈和录音,并将录音打印成文字资料。 相似文献
48.
A 2.5-month-old, 30 kg Duroc pig died 10 days after showing clinical signs of dyspnoea and diarrhoea. Acute necrotizing and fibrinous pleuropneumonia with locally extensive lesions was found. Chromobacterium violaceum was isolated from pneumonic lung tissues and intratracheal inoculation of a pure culture into two SPF pigs reproduced lesions similar to those found in the natural infection. 相似文献
49.
Ding Y He L Zhang Q Huang Z Che X Hou J Wang H Shen H Qiu L Li Z Geng J Cai J Han H Li X Kang W Weng D Liang P Jiang S 《The Journal of pathology》2004,203(2):622-630
We previously identified the major pathological changes in the respiratory and immune systems of patients who died of severe acute respiratory syndrome (SARS) but gained little information on the organ distribution of SARS-associated coronavirus (SARS-CoV). In the present study, we used a murine monoclonal antibody specific for SARS-CoV nucleoprotein, and probes specific for a SARS-CoV RNA polymerase gene fragment, for immunohistochemistry and in situ hybridization, respectively, to detect SARS-CoV systematically in tissues from patients who died of SARS. SARS-CoV was found in lung, trachea/bronchus, stomach, small intestine, distal convoluted renal tubule, sweat gland, parathyroid, pituitary, pancreas, adrenal gland, liver and cerebrum, but was not detected in oesophagus, spleen, lymph node, bone marrow, heart, aorta, cerebellum, thyroid, testis, ovary, uterus or muscle. These results suggest that, in addition to the respiratory system, the gastrointestinal tract and other organs with detectable SARS-CoV may also be targets of SARS-CoV infection. The pathological changes in these organs may be caused directly by the cytopathic effect mediated by local replication of the SARS-CoV; or indirectly as a result of systemic responses to respiratory failure or the harmful immune response induced by viral infection. In addition to viral spread through a respiratory route, SARS-CoV in the intestinal tract, kidney and sweat glands may be excreted via faeces, urine and sweat, thereby leading to virus transmission. This study provides important information for understanding the pathogenesis of SARS-CoV infection and sheds light on possible virus transmission pathways. This data will be useful for designing new strategies for prevention and treatment of SARS. 相似文献
50.
Risk estimates promulgated by various radiation protection authorities in recent years have become increasingly more complex. Early "integral" estimates in the form of health effects per 0.01 person-Gy (per person-rad) or per 10(4) person-Gy (per 10(6) person-rad) have tended to be replaced by "differential" estimates which are age- and sex-dependent and specify both minimum induction (latency) and duration of risk expression (plateau) periods. These latter types of risk estimate must be used in conjunction with a life table in order to reduce them to integral form. In this paper, the life table has been used to effect a comparison of the organ and tissue risk estimates derived in several recent reports. In addition, a brief review of life-table methodology is presented and some features of the models used in deriving differential coefficients are discussed. While the great number of permutations possible with dose-response models, detailed risk estimates and proposed projection models precludes any unique result, the reduced integral coefficients are required to conform to the linear, absolute-risk model recommended for use with the integral risk estimates reviewed. 相似文献