全文获取类型
收费全文 | 871篇 |
免费 | 46篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 75篇 |
妇产科学 | 4篇 |
基础医学 | 91篇 |
口腔科学 | 85篇 |
临床医学 | 114篇 |
内科学 | 118篇 |
皮肤病学 | 11篇 |
神经病学 | 35篇 |
特种医学 | 112篇 |
外科学 | 95篇 |
综合类 | 25篇 |
预防医学 | 77篇 |
眼科学 | 9篇 |
药学 | 53篇 |
中国医学 | 1篇 |
肿瘤学 | 30篇 |
出版年
2021年 | 18篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 21篇 |
2012年 | 27篇 |
2011年 | 28篇 |
2010年 | 28篇 |
2009年 | 19篇 |
2008年 | 29篇 |
2007年 | 58篇 |
2006年 | 40篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 28篇 |
2002年 | 36篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 29篇 |
1998年 | 24篇 |
1997年 | 25篇 |
1996年 | 28篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 25篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 19篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1972年 | 7篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1954年 | 4篇 |
排序方式: 共有952条查询结果,搜索用时 31 毫秒
101.
David M Murdoch Melinda S Suchard Willem DF Venter Patrick Mhlangu Janet S Ottinger Charles Feldman Annelies Van Rie Deborah K Glencross Wendy S Stevens Kent J Weinhold 《AIDS research and therapy》2009,6(1):16-9
Objective
To immunophenotype CD4+ and CD8+ T cell sub-populations in HIV-associated immune reconstitution inflammatory syndrome (IRIS). 相似文献102.
Joachim Polligkeit Martin Grimm Jens P. Peters Marcel Cetindis Michael Krimmel Siegmar Reinert 《Journal of cranio-maxillo-facial surgery》2013,41(8):797-802
BackgroundThe treatment of complex orbital floor fractures with extensive orbital prolapse remains a surgical challenge in craniomaxillofacial traumatology and is still controversially discussed. Reduction of orbital tissue via a transcutaneous or transconjunctival approach alone can be very difficult and lead to unsatisfying results.MethodsOver a 3-year-period, we enrolled 13 patients who underwent endoscopy-assisted reconstruction of isolated orbital floor fractures via a combined subciliary and transantral approach. Patient data, imaging and ophthalmologic examination were reviewed prospectively.ResultsTen patients underwent primary surgical treatment, 3 patients had secondary surgical treatment because of unsatisfactory results of primary surgical intervention. All patients had an uneventful postoperative course without ophthalmologic deterioration, no further surgical procedures were necessary.ConclusionsThe additional use of an endoscopy-assisted transantral approach provides a reliable treatment modality in selected cases. To our knowledge, this is the only study of patients treated with a combined subciliary and transantral approach. Special emphasis was given to postoperative functional results, a short algorithm for use of an additional transantral endoscopy-assisted approach is presented. 相似文献
103.
Summary. SSP-7 is a protein originally isolated from stallion seminal plasma. It has extensive amino acid sequence homology with boar spermadhesin AWN, and, like its porcine counterpart, SSP-7 displays zona pellucida-binding activity. Strikingly, however, immunohistochemical studies presented here show that the stallion and the boar spermadhesin homologues are secreted at different places of the male genital tract. Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover the entire acrosomal cap membrane. The different cellular origin and compartimentalization of spermadhesin molecules in different species suggest that structurally related proteins could be involved in species-specific aspects of mammalian fertilization. 相似文献
104.
105.
Neal S Beall B Ekelund K Henriques-Normark B Jasir A Johnson D Kaplan E Lovgren M Reinert RR;Strep-EURO Study Group;International Streptococcus Reference Laboratories Efstratiou A 《Journal of clinical microbiology》2007,45(4):1175-1179
Surveillance of group A streptococcal (GAS) infections was undertaken as a major component of the European Commission-funded project on severe GAS disease in Europe (strep-EURO). One aim of strep-EURO was to improve the quality of GAS characterization by standardization of methods. An external quality assurance study (EQA) was therefore carried out to evaluate current global performance. Eleven strep-EURO and seven other streptococcal reference centers received a panel of 20 coded GAS isolates for typing. Conventional phenotypic typing (based on cell surface T and M protein antigens and opacity factor [OF] production) and molecular methods (emm gene typing) were used either as single or combined approaches to GAS typing. T typing was performed by 16 centers; 12 centers found one or more of the 20 strains nontypeable (typeability, 89%), and 11 centers reported at least one incorrect result (concordance, 93%). The 10 centers that tested for OF production achieved 96% concordance. Limited availability of antisera resulted in poor typeability values from the four centers that performed phenotypic M typing (41%), three of which also performed anti-OF typing (typeability, 63%); however, concordance was high for both M (100%) and anti-OF (94%) typing. In contrast, the 15 centers that performed emm gene sequencing achieved excellent typeability (97%) and concordance (98%), although comparison of the performance between centers yielded typeability rates from 65 to 100% and concordance values from 83 to 100%. With the rapid expansion and use of molecular genotypic methods to characterize GAS, continuation of EQA is essential in order to achieve international standardization and comparison of type distributions. 相似文献
106.
MR Carvalho ; MA Krieger ; E Almeida ; W Oelemann ; MA Shikanai-Yassuda ; AW Ferreira ; JB Pereira ; A Saez-Alquezar ; PE Dorlhiac-Llacer ; DF Chamone ; et al. 《Transfusion》1993,33(10):830-834
Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease. 相似文献
107.
Beta thalassemia in Melanesia: association with malaria and characterization of a common variant (IVS-1 nt 5 G----C) 总被引:3,自引:0,他引:3
Data on the distribution of beta thalassemia among over 6,000 Melanesians reveals a major difference in the carrier rates between populations in the malarious coastal regions of New Guinea and those living in the historically malaria-free Highlands. The island of Maewo in Vanuatu has a particularly high incidence of beta + thalassemia associated with a single restriction enzyme haplotype. Direct cloning into a plasmid vector and sequence analysis demonstrate that the mutation is a G to C transversion at position 5 of intron 1 of the beta- globin gene. Oligonucleotide probe surveys indicate that this variant accounted for all cases of beta thalassemia studied from Maewo. It is also common in coastal Papua New Guinea where haplotype and oligonucleotide probe data suggest that the molecular basis of beta thalassmia is more heterogeneous. 相似文献
108.
Protein C, an antithrombotic protein, is reduced in hospitalized patients with intravascular coagulation 总被引:7,自引:0,他引:7
Activated protein C is a potent anticoagulant and profibrinolytic enzyme that can be derived from the vitamin-K-dependent serine protease zymogen, protein C, by the action of thrombin. Protein C antigen concentration was determined in plasmas from normals (n = 40) and from 38 patients with intravascular coagulation as evidenced by positive FDP (greater than micrograms/ml). Plasma protein C was 4 micrograms/ml in normals and was significantly depressed (less than 2 SD below the mean of normals) in 19 of the 38 patients. Of 15 patients with suspected intravascular coagulation but normal FDP, protein C was decreased in 5 individuals; 3 of these 5 patients had liver disease. Based on these results, we suggest that extensive activation of the coagulation system in vivo causes a significant consumption of protein C, presumably due to its activation by thrombin and subsequent clearance. 相似文献
109.
Susanne Kluba Fabian Roßkopf Wiebke Kraut Jens Peter Peters Benjamin Calgeer Siegmar Reinert Michael Krimmel 《Clinical oral investigations》2016,20(9):2395-2401
Objectives
Asymmetries of the jaw and orthodontic abnormalities are suspected as long-term consequences of positional cranial deformity. But only few data exist on this issue. As plagiocephaly is a common problem in infancy, potential functional impairments should be investigated to initiate appropriate measures if necessary. The aim of our study was to compare the orthodontic situation in primary dentition of children with positional plagiocephaly and children without cranial deformities.Material and methods
Fifty children treated by helmet therapy for plagiocephaly and 50 non-affected children (age 1.98–5.69 years) were examined in a cross-sectional study. Orthodontic parameters of all dimensions were assessed and analyzed.Results
Children of the plagiocephalic group showed more often orthodontic alterations compared to the others. Especially the frequencies of a class II malocclusion (36 vs. 14 %), an edge-to edge bite (28 vs. 12 %), and deviations of the midline (38 vs. 16 %) were conspicuous. However, none of the differences was significant (p > 0.003). Of all observed mandibular asymmetries, 69 % appeared as a shift to the contralateral side of the former flattened occipital region.Conclusion
Positional head deformity might be associated in some cases with a higher prevalence of occlusal abnormalities in primary dentition.Clinical relevance
Positional plagiocephaly interfaces medicine and dentistry. As it is a common disorder, this etiology has to be considered in the prevention and therapy of malocclusion.110.
The magnetic resonance (MR) relaxation rates of protons were compared in the myelinated and nonmyelinated nerves of the garfish. The long, large olfactory nerve of the garfish, as an easily accessible source of nonmyelinated axons, is uniquely suited for such a comparison. The T1 and T2 measurements revealed distinct and consistent differences between nonmyelinated olfactory nerves and myelinated optic and oculomotor nerves. Comparisons between water content, lipid content, and relaxation rates indicated that the differences in MR properties represent complex differences in the distribution and physical environment of the constituent lipid and water protons. 相似文献