全文获取类型
收费全文 | 13487篇 |
免费 | 963篇 |
国内免费 | 148篇 |
专业分类
耳鼻咽喉 | 96篇 |
儿科学 | 467篇 |
妇产科学 | 408篇 |
基础医学 | 1811篇 |
口腔科学 | 279篇 |
临床医学 | 1197篇 |
内科学 | 2609篇 |
皮肤病学 | 230篇 |
神经病学 | 926篇 |
特种医学 | 518篇 |
外科学 | 2290篇 |
综合类 | 627篇 |
一般理论 | 4篇 |
预防医学 | 729篇 |
眼科学 | 351篇 |
药学 | 767篇 |
1篇 | |
中国医学 | 80篇 |
肿瘤学 | 1208篇 |
出版年
2023年 | 134篇 |
2022年 | 187篇 |
2021年 | 340篇 |
2020年 | 237篇 |
2019年 | 307篇 |
2018年 | 340篇 |
2017年 | 266篇 |
2016年 | 296篇 |
2015年 | 354篇 |
2014年 | 450篇 |
2013年 | 551篇 |
2012年 | 865篇 |
2011年 | 923篇 |
2010年 | 558篇 |
2009年 | 494篇 |
2008年 | 730篇 |
2007年 | 716篇 |
2006年 | 722篇 |
2005年 | 702篇 |
2004年 | 679篇 |
2003年 | 599篇 |
2002年 | 559篇 |
2001年 | 527篇 |
2000年 | 413篇 |
1999年 | 356篇 |
1998年 | 130篇 |
1997年 | 130篇 |
1996年 | 115篇 |
1995年 | 97篇 |
1994年 | 88篇 |
1993年 | 58篇 |
1992年 | 164篇 |
1991年 | 155篇 |
1990年 | 168篇 |
1989年 | 167篇 |
1988年 | 139篇 |
1987年 | 144篇 |
1986年 | 116篇 |
1985年 | 91篇 |
1984年 | 56篇 |
1983年 | 44篇 |
1981年 | 36篇 |
1980年 | 31篇 |
1979年 | 54篇 |
1978年 | 41篇 |
1977年 | 44篇 |
1976年 | 28篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1973年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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
92.
Allelic loss of chromosome 6q in gastric carcinoma. 总被引:1,自引:0,他引:1
Brenda C Y Li Wing Y Chan Christine Y S Li Chit Chow Enders K W Ng S C Sydney Chung 《Diagnostic molecular pathology》2003,12(4):193-200
Loss of the long arm of chromosome 6 (6q) has frequently been reported in gastric carcinoma, and most gastric cancer patients have evidence of intestinal metaplasia in the stomach. However, the relationship between loss of chromosome 6q and intestinal metaplasia has not been studied. In the first part of the study, we define the critical deletion region of chromosome 6q using loss of heterozygosity technique (LOH). Seventeen microsatellite markers were used to detect loss of heterozygosity (LOH) in 37 microdissected gastric tumors. We also examined intestinal metaplasia (IM) foci of the stomach in the same cancer patient (17 cases). Losses on chromosome 6q were detected in high frequency (51%) by LOH. Two distinct regions of common allelic loss were identified: one centered on the marker D6S300 (at 6q16.1) and the second on D6S446 (at 6q27), with LOH frequency of 36% and 31.3%, respectively. The deletions fall into 2 discrete regions, suggesting the existence of at least 2 tumor suppressor genes in 6q. The losses at 6q27 were confirmed by fluorescence in situ hybridization study (FISH). In the cases with LOH in the tumor, no LOH were detected in the autologous IM areas, but losses were detected by FISH. In some cases, these genetic changes may be acquired in the transition from normal gastric mucosa to intestinal metaplasia. 相似文献
93.
K.K.W. To C.C.Y. Yip C.Y.W. Lai C.K.H. Wong D.T.Y. Ho P.K.P. Pang A.C.K. Ng K.-H. Leung R.W.S. Poon K.-H. Chan V.C.C. Cheng I.F.N. Hung K.-Y. Yuen 《Clinical microbiology and infection》2019,25(3):372-378
Objectives
Automated point-of-care molecular assays have greatly shortened the turnaround time of respiratory virus testing. One of the major bottlenecks now lies at the specimen collection step, especially in a busy clinical setting. Saliva is a convenient specimen type that can be provided easily by adult patients. This study assessed the diagnostic validity, specimen collection time and cost associated with the use of saliva.Methods
This was a prospective diagnostic validity study comparing the detection rate of respiratory viruses between saliva and nasopharyngeal aspirate (NPA) among adult hospitalized patients using Xpert® Xpress Flu/RSV. The cost and time associated with the collection of saliva and nasopharyngeal specimens were also estimated.Results
Between July and October 2017, 214 patients were recruited. The overall agreement between saliva and NPA was 93.3% (196/210, κ 0.851, 95% CI 0.776–0.926). There was no significant difference in the detection rate of respiratory viruses between saliva and NPA (32.9% (69/210) versus 35.7% (75/210); p 0.146). The overall sensitivity and specificity were 90.8% (81.9%–96.2%) and 100% (97.3%–100%), respectively, for saliva, and were 96.1% (88.9%–99.2%) and 98.5% (94.7%–99.8%), respectively, for NPA. The time and cost associated with the collection of saliva were 2.26-fold and 2.59-fold lower, respectively, than those of NPA.Conclusions
Saliva specimens have high sensitivity and specificity in the detection of respiratory viruses by an automated multiplex Clinical Laboratory Improvement Amendments-waived point-of-care molecular assay when compared with those of NPA. The use of saliva also reduces the time and cost associated with specimen collection. 相似文献94.
Summary An extended follow-up study of hepatitis C virus (HVC) infection was conducted in Guangzhou and its nearby regions on patients hospitalized with acute hepatitis. Routine screening of blood donors for HCV was not yet instituted at the time of this study. HCV was found to be a common cause of the disease, and the infection had a close association with recent histories of blood transfusion. Sequential sera obtained from patients during hospitalization and after discharge were tested for the presence of HCV antibodies by the first and the second generation of commercial test kits, for levels of alanine aminotransferase (ALT), and for the presence of HCV-RNA. The development of HCV antibodies in some of the patients may be delayed for protracted period following clinical onset. HCV-RNA was only intermittently detectable both before and after seroconversion. Six of 33 patients studied showed seroreversion and 5 of them were accompanied by loss of HCV-RNA and serum ALT returned to normal levels. The disease persisted in 24 of 27 patients without seroreversion, accompanied by intermittent detection of HCV-RNA throughout the protracted course of the infection. Our results indicate that both EIA for detection of HCV antibodies and PCR for serum HCV-RNA should be used in combination for reliable diagnosis of HCV infection and screening of blood for transfusion. 相似文献
95.
p53蛋白的免疫亲和层析纯化 总被引:2,自引:0,他引:2
建立了p53单克隆抗体pAb1801的免疫亲和层极法纯化p53蛋白,所纯化的p53蛋白经Western Blot(ECL法)检测证明:用此法从p53阳性的SW480细胞中分离到p53蛋白。银染显示pH2.0甘氨酸缓冲液比pH2.8的甘氨酸缓冲液洗脱效果好,这种方法的建立将为分离肿瘤细胞中引起p53蛋白功能失活和研究肿瘤发生机制提供一种有效途径。 相似文献
96.
Abstract: Low and high resolution sequence specific oligonucleotide probe hybridization patterns were used to design an approach to direct sequencing of allele specific amplified cDNA. Several PCR amplifications were used to derive overlapping sequence fragments to define complete first domain sequences for a single allele. This method has been used to characterize three new DRB1 alleles in the DR52 family, DRB1*1115, DRB1* 1117, and DRB1*1319. All three alleles carry polymorphisms previously observed in other DRB alleles and underscore the importance of utilizing a directed sequencing approach for obtaining unambiguous typing results in matching for bone marrow transplantation between unrelated donor and recipient. 相似文献
97.
Summary Epstein Barr Virus (EBV) receptor activity in cell free extracts is operationally defined as one which causes a reduction in the effective concentration of the early antigen inducing particles of an EBV preparation when the latter is preincubated with the extract before infection. Such activity was detected in the surface extract of Raji cells and to a lesser extent in that of BJAB cells, both of which are B lymphoblastoid cells that are susceptible to infection with EBV. Receptor activity was not detected in similar extracts of P3HR-1 cells and human diploid fibroblasts neither of which are known to be susceptible to EBV infection.Receptor activity in the Raji cell extract was found to be associated with membranous structures. This may have rendered the activity resistant to treatment with trypsin and sonication. The activity was however abrogated if the extract was exposed to neutral detergent.Binding of receptor activity was observed when Raji cell extract was chromatographed on a column of immobilized EBV. Subsequent electrophoretic analysis showed however that this procedure did not result in an appreciable purification of the receptor activity. Neutral detergent treated extract was similarly chromatographed. The resulting eluates did not contain detectable receptor activity but were less heterogeneous in protein content as compared with that of the original extract. It is not certain at present if these EBV binding proteins are involved in the receptor activity of the extract.With 3 Figures 相似文献
98.
Case report: human herpesvirus 7 associated fatal encephalitis in a peripheral blood stem cell transplant recipient 总被引:2,自引:0,他引:2
Chan PK Chik KW To KF Li CK Shing MM Ng KC Yuen PM Cheng AF 《Journal of medical virology》2002,66(4):493-496
Previous studies have suggested a neuroinvasive and neuropersistent potential of human herpesvirus 7 (HHV-7). In this report, a case of fatal encephalitis is described and its association with HHV-7 infection is discussed. An 8-year-old girl received a peripheral blood stem cell transplant for relapsed acute lymphoblastic leukaemia. The post-transplant period was uneventful and a course of intrathecal chemotherapy was given on Day-30. On Day-41, she developed acute encephalopathy with diplopia and nystagmus. She ran a rapid downhill course and succumbed despite antiviral treatment. The only positive pathological finding was the multiple microscopic foci of haemorrhage associated with neuronal degeneration detected in the brain stem. All microbiological investigations were negative, except for the presence of HHV-7 DNA in cerebrospinal fluid and brain stem tissue samples. 相似文献
99.
Marks GB Ng K Zhou J Toelle BG Xuan W Belousova EG Britton WJ 《The Journal of allergy and clinical immunology》2003,111(3):541-549
BACKGROUND: There are conflicting reports on the effect of BCG vaccination on the subsequent development of atopy and asthma. There are no data on the effects of neonatal BCG vaccination on cytokine responses of lymphocytes that are exposed in vitro to allergens. OBJECTIVES: We sought to test the hypothesis that neonatal BCG vaccination or, alternatively, evidence of an immunologic memory of this vaccination is associated with a reduced prevalence of allergic sensitization, asthma, eczema, and hay fever during childhood. METHODS: An historical cohort study was conducted among 7- to 14-year-old children who were born in 2 districts in Sydney, Australia, and whose mothers were born in southeast Asia. One district had routinely administered BCG vaccination to infants born to overseas-born mothers and the other had not. Eligible subjects were identified from birth registers. Consenting subjects completed questionnaires, performed spirometric and airway hyperresponsiveness testing, and had allergen skin prick testing and tuberculin skin testing. Blood was collected to measure total serum IgE levels and for in vitro lymphocyte culture in the presence of an extract of house dust mite, the dominant allergen in this region, and purified protein derivative of Mycobacterium tuberculosis (tuberculin). IL-4, IL-5, IL-10, and IFN-gamma were measured in the culture supernatant. RESULTS: The cohort included 309 BCG-vaccinated subjects and 442 non-BCG-vaccinated subjects. BCG-vaccinated subjects did not have a lower rate of allergic sensitization than nonvaccinated subjects. However, among the subgroup of subjects with a family history of rhinitis or eczema, BCG vaccination was associated with a lower prevalence of current asthma (defined as recent wheezing plus airway hyperresponsiveness; relative risk, 0.46; 95% CI, 0.22-0.95). BCG vaccination was also associated with lower levels of allergen-stimulated IL-10 production in vitro. Among the BCG-vaccinated subjects, the 44 (14.3%) who had tuberculin skin test reaction sizes of 5 mm or greater and the 31 (18.3%) who demonstrated an in vitro IFN-gamma response to purified protein derivative of M tuberculosis did not have lower rates of allergic sensitization and, overall, did not have a lower prevalence of allergic disease than tuberculin skin test or IFN-gamma nonreactors. CONCLUSION: We conclude that neonatal BCG vaccination has an effect on T-cell allergen responsiveness 7 to 14 years after vaccination and that among a subgroup of subjects with an inherited predisposition to allergic disease, this is associated with clinically relevant beneficial effects. The findings of this study encourage the view that external influences on the immune system in the neonatal period have consequences that extend into later childhood and influence the expression of asthma. Genetic factors are likely to modify the effect of those external factors. 相似文献
100.
Collision tumour of the oesophagus: a challenge for histological diagnosis. 总被引:2,自引:0,他引:2 下载免费PDF全文
An unusual case of mantle cell lymphoma metastasising to squamous cell carcinoma of the oesophagus, in a 62 year old Chinese man, is reported. A histological diagnosis based on examination of a small endoscopic biopsy specimen, in the absence of detailed clinical information, may be difficult, as the lymphoma component can be mistaken for reactive lymphoid infiltrate which is sometimes present adjacent to squamous cell carcinoma. Correlation with the clinical history, careful assessment of the subtle histological changes, and use of ancillary methods such as immunohistochemistry are most helpful in making the correct diagnosis. This case also illustrates further the possible occurrence of lymphomatous infiltrates surrounding other lesions in patients with a previous or concurrent history of lymphoma. 相似文献