全文获取类型
收费全文 | 14494篇 |
免费 | 1086篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 152篇 |
儿科学 | 567篇 |
妇产科学 | 269篇 |
基础医学 | 1912篇 |
口腔科学 | 348篇 |
临床医学 | 1286篇 |
内科学 | 3734篇 |
皮肤病学 | 432篇 |
神经病学 | 1140篇 |
特种医学 | 287篇 |
外国民族医学 | 1篇 |
外科学 | 1822篇 |
综合类 | 80篇 |
一般理论 | 17篇 |
预防医学 | 1527篇 |
眼科学 | 230篇 |
药学 | 887篇 |
中国医学 | 63篇 |
肿瘤学 | 868篇 |
出版年
2023年 | 132篇 |
2022年 | 246篇 |
2021年 | 511篇 |
2020年 | 276篇 |
2019年 | 473篇 |
2018年 | 555篇 |
2017年 | 372篇 |
2016年 | 336篇 |
2015年 | 427篇 |
2014年 | 536篇 |
2013年 | 722篇 |
2012年 | 1034篇 |
2011年 | 1078篇 |
2010年 | 623篇 |
2009年 | 541篇 |
2008年 | 842篇 |
2007年 | 825篇 |
2006年 | 764篇 |
2005年 | 791篇 |
2004年 | 665篇 |
2003年 | 657篇 |
2002年 | 619篇 |
2001年 | 333篇 |
2000年 | 359篇 |
1999年 | 274篇 |
1998年 | 116篇 |
1997年 | 82篇 |
1996年 | 94篇 |
1995年 | 78篇 |
1994年 | 63篇 |
1993年 | 43篇 |
1992年 | 154篇 |
1991年 | 126篇 |
1990年 | 94篇 |
1989年 | 92篇 |
1988年 | 94篇 |
1987年 | 84篇 |
1986年 | 73篇 |
1985年 | 67篇 |
1984年 | 45篇 |
1983年 | 34篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1979年 | 27篇 |
1978年 | 15篇 |
1977年 | 21篇 |
1976年 | 18篇 |
1973年 | 24篇 |
1972年 | 17篇 |
1971年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Wagner A van der Klift H Franken P Wijnen J Breukel C Bezrookove V Smits R Kinarsky Y Barrows A Franklin B Lynch J Lynch H Fodde R 《Genes, chromosomes & cancer》2002,35(1):49-57
Genomic deletions of the MSH2 gene are a frequent cause of hereditary nonpolyposis colorectal cancer (HNPCC), a common hereditary predisposition to the development of tumors in several organs including the gastrointestinal and urinary tracts and endometrium. The mutation spectrum at the MSH2 gene is extremely heterogeneous because it includes nonsense and missense point mutations, small insertions and deletions leading to frameshifts, and larger genomic deletions, the latter representing approximately 25% of the total mutation burden. Here, we report the identification and molecular characterization of the first paracentric inversion of the MSH2 locus known to cause HNPCC. Southern blot analysis and inverse PCR showed that the centromeric and telomeric breakpoints of the paracentric inversion map within intron 7 and to a contig 10 Mb 3' of MSH2, respectively. Pathogenicity of the paracentric inversion was demonstrated by conversion analysis. The patient's lymphocytes were employed to generate somatic cell hybrids to analyze the expression of the inverted MSH2 allele in an Msh2-deficient rodent cellular background. The inversion was shown to abolish MSH2 expression by both northern and western analysis. This study confirms that Southern blot analysis still represents a useful and informative tool to screen for and identify complex genomic rearrangements in HNPCC. Moreover, monoallelic expression analysis represents an attractive approach to demonstrate pathogenicity of unusual mutations in autosomal dominant hereditary conditions. 相似文献
92.
Immunohistochemical classification of non-BRCA1/2 tumors identifies different groups that demonstrate the heterogeneity of BRCAX families. 总被引:1,自引:0,他引:1
Emiliano Honrado Ana Osorio Roger L Milne María F Paz Lorenzo Melchor Alberto Cascón Miguel Urioste Alicia Cazorla Orland Díez Enrique Lerma Manel Esteller José Palacios Javier Benítez 《Modern pathology》2007,20(12):1298-1306
Around 25% of hereditary breast and ovarian cancer families have mutations in the BRCA1 and BRCA2 genes. The search for other genes has until now failed, probably because there is not one single BRCAX gene, but rather various genes that may each be responsible for a small number of breast cancer families and/or may interact according to a polygenic model. We have studied 50 tumors from probands belonging to non-BRCA1/2 breast cancer families (BRCAX), using 25 immunohistochemical markers. The objective was to classify these tumors and confirm that they are heterogeneous. Unsupervised cluster analysis showed the existence of the following two main groups of tumors: high-grade and estrogen receptor (ER)-negative tumors (50%), and low-grade and ER-positive tumors (50%). In addition we identified five subgroups, three among the high-grade and two among the low-grade groups; one overexpressing HER-2 (18%); one with a basal-like phenotype (14%); one with a normal breast-like phenotype (18%); a luminal A subgroup (36%), and a luminal B subgroup (14%). Hypermethylation of the BRCA1 gene was observed in 42% of the cases, spread across all five subgroups, but only 37% of those had loss of heterozygosity as well. These latter cases were all clustered in the high-grade group and the majority of them in the basal-like subgroup. Our results show that familial non-BRCA1/2 tumors are heterogeneous and suggest a polygenic model for explaining the majority of BRCAX families. In addition we have defined a subset of them that have somatic inactivation of the BRCA1 gene. 相似文献
93.
The restorative effect of naps on perceptual deterioration 总被引:4,自引:0,他引:4
Mednick SC Nakayama K Cantero JL Atienza M Levin AA Pathak N Stickgold R 《Nature neuroscience》2002,5(7):677-681
Human performance on visual texture discrimination tasks improves slowly (over days) in the absence of additional training. This 'slow learning' requires nocturnal sleep after training and is limited to the region of visual space in which training occurred. Here, we tested human subjects four times in one day and found that with repeated, within-day testing, perceptual thresholds actually increased progressively across the four test sessions. This performance deterioration was prevented either by shifting the target stimuli to an untrained region of visual space or by having the subjects take a mid-day nap between the second and third sessions. 相似文献
94.
Maria E Tosello Marisa S Biasoli Alicia G Luque Hortensia M Magaró Adriana R Krapp 《Medical mycology》2007,45(6):535-540
Candida dubliniensis is a yeast species closely related to Candida albicans, but in contrast to C. albicans, limited information is available on the virulence factors of this important fungal pathogen. The objective of the present study was to determine if this species was able to evoke an adaptive response to oxidants. C. dubliniensis, treated with a low concentration of either H(2)O(2) or methyl viologen (a superoxide generating agent), mounts an adaptive response that results in increased survival against lethal doses of both oxidants. This response was characterized by the induction of enzymes with known antioxidant function. C. dubliniensis strains were less resistant to oxidants than C. albicans, displaying higher susceptibility to their toxic effects. The adaptive response described here might be responsible, among other factors, for the ability of this pathogen to cause infections in individuals with impaired immunity. 相似文献
95.
Heteroplasmy for the 1555A>G mutation in the mitochondrial 12S rRNA gene in six Spanish families with non-syndromic hearing loss
下载免费PDF全文
![点击此处可从《Journal of medical genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
96.
E. Estefanía N. Gmez‐Lozano R. De Pablo M. E. Moreno C. Vilches 《International journal of immunogenetics》2003,30(1):11-12
We have isolated the complete coding region of HLA‐B*39 from a Spanish Caucasoid, using a new PCR primer for its 5′ untranslated region. The cDNA matched partial genomic sequences of B*3924, an allele whose distribution appears to be restricted to Mediterranean and Arabian Caucasoids. A single amino acid change exclusive to B*3924 (threonine‐98) distinguishes it from B*3903. 相似文献
97.
Pérez C Tous M Gallego S Zala N Rabinovich O Garbiero S Martínez MJ Cunha AM Camino S Cámara A Costa SC Larrondo M Francalancia V Landreau F Bartomioli MA 《Journal of medical virology》2004,72(4):661-667
Human herpesvirus-8 (HHV-8) causes Kaposi's sarcoma (KS) and lymphoproliferative disorders in both HIV-infected and uninfected patients. HHV-8 has a worldwide occurrence but infection rates vary according to a combination of geographic and behavioral risks. The main transmission route seems to be sexual, nevertheless, nasal secretions, saliva, blood, and organ graft have been proposed. HHV-8 was postulated as a new infectious agent for screening in blood donors. The aim of this study was to evaluate the prevalence of antibodies against HHV-8 antigens in blood donors of South America. Serum samples from 2,470 blood donors from Argentina, Brazil, and Chile corresponding to five geographic regions were studied by indirect immunofluorescence assay (IFA). Seroprevalence rate was 3.7% (92/2,470; 95% CI 2.9-4.5) in the entire blood donor population distributed as follows: Argentina, 4.0% (Buenos Aires city, 4.3%; Bahia Blanca, 2.4%; and Córdoba, 4.0%), Campinas (Brazil), 2.8%; and Santiago de Chile, 3.0%. There was no difference (P>0.05) between men and women or age related, except in Brazil where positive cases were 30-49-year-old males. The present study, which includes different geographical areas of multiple countries from South America, has not been done before. The results show similar prevalence rates among the studied zones corresponding to low-prevalence regions. South America is a large sub-continent with a wide spectrum of population and geographical characteristics, thus, more HHV-8 prevalence studies should be necessary to establish possible regional differences. 相似文献
98.
Diagnostic utility of a multiplex herpesvirus PCR assay performed with cerebrospinal fluid from human immunodeficiency virus-infected patients with neurological disorders 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Quereda C Corral I Laguna F Valencia ME Tenorio A Echeverria JE Navas E Martín-Dávila P Moreno A Moreno V Gonzalez-Lahoz JM Arribas JR Guerrero A 《Journal of clinical microbiology》2000,38(8):3061-3067
We used a multiplex nested-PCR assay for the simultaneous detection in cerebrospinal fluid (CSF) of five human herpesviruses (HVs) (cytomegalovirus [CMV], Epstein-Barr virus [EBV], varicella-zoster virus [VZV], herpes simplex virus [HSV], and human herpesvirus 6 [HHV-6]) in a clinical evaluation of human immunodeficiency virus (HIV)-infected patients with neurological disorders. This method, which has the advantages of being rapid and economical, would be of particular interest for the diagnosis of neurological syndromes caused by more than one HV. We studied 251 CSF samples from 219 patients. HV DNA was demonstrated in 93 (37%) of the CSF samples (34% of the patients). CMV was the HV most frequently detected in our patients (25%), while EBV, VZV, HSV, and HHV-6 DNAs were present in significantly fewer cases (7, 4, 3, and 1%, respectively). When results were compared with the final etiological diagnoses of the patients, the multiplex HV PCR showed high specificity for the diagnosis of CMV and VZV neurological diseases and for cerebral lymphoma (0.95, 0.97, and 0.99, respectively). The sensitivity of the assay was high for CMV disease (0.87), was low for cerebral lymphoma (0.33), and was not evaluable for VZV disease due to the small number of patients with this diagnosis. Nevertheless, detection of VZV DNA had possible diagnostic value in four of the nine cases, and EBV DNA amplification always predicted the diagnosis of cerebral lymphoma in patients with cerebral masses. Detection of HSV DNA was frequently associated with CMV amplification and fatal encephalitis. HHV-6 was not considered to have a pathogenetic role in the three cases in which it was detected. This multiplex HV PCR assay is a specific and clinically useful method for the evaluation of HIV-infected patients with neurological disorders related to HV. 相似文献
99.
Angel González-Sistal M.D. Ph.D. Alicia Baltasar Sánchez M.D. 《Journal of digital imaging》2006,19(3):270-275
Purpose This study was conducted to evaluate the diagnostic usefulness of gray level parameters in order to distinguish healthy bone
from osteoblastic metastases on digitized radiographs.
Materials and methods Skeletal radiographs of healthy bone (n = 144) and osteoblastic metastases (n = 35) were digitized using pixels 0.175 mm in size and 4,096 gray levels. We obtained an optimized healthy bone classification
to compare with pathological bone: cortical, trabecular, and flat bone. The osteoblastic metastases (OM) were classified in
nonflat and flat bone. These radiological images were analyzed by using a computerized method. The parameters (gray scale)
calculated were: mean, standard deviation, and coefficient of variation (MGL, SDGL, and CVGL, respectively) based on gray
level histogram analysis. Diagnostic utility was quantified by measurement of parameters on healthy and pathological bone,
yielding quantification of area under the receiver operating characteristic (ROC) curve, AUC.
Results All three image parameters showed high and significant values of AUC when comparing healthy trabecular bone and nonflat bone
OM, showing MGL the best discriminatory ability (0.97). As for flat bones, MGL showed no ability to distinguish between healthy
and flat bone OM (0.50). This could be achieved by using SDGL or CVGL, with both showing a similar diagnostic ability (0.85
and 0.83, respectively).
Conclusion Our results show that the use of gray level parameters quantify healthy bone and osteoblastic metastases zones on digitized
radiographs. This may be helpful as a complementary method for differential diagnosis. Moreover, our method will allow us
to study the evolution of osteoblastic metastases under medical treatment. 相似文献
100.