全文获取类型
收费全文 | 12255篇 |
免费 | 900篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 332篇 |
妇产科学 | 290篇 |
基础医学 | 1672篇 |
口腔科学 | 273篇 |
临床医学 | 1147篇 |
内科学 | 2814篇 |
皮肤病学 | 418篇 |
神经病学 | 1030篇 |
特种医学 | 650篇 |
外科学 | 1503篇 |
综合类 | 108篇 |
一般理论 | 3篇 |
预防医学 | 864篇 |
眼科学 | 355篇 |
药学 | 658篇 |
1篇 | |
中国医学 | 21篇 |
肿瘤学 | 1009篇 |
出版年
2023年 | 104篇 |
2022年 | 202篇 |
2021年 | 396篇 |
2020年 | 230篇 |
2019年 | 326篇 |
2018年 | 390篇 |
2017年 | 280篇 |
2016年 | 278篇 |
2015年 | 351篇 |
2014年 | 450篇 |
2013年 | 660篇 |
2012年 | 795篇 |
2011年 | 858篇 |
2010年 | 468篇 |
2009年 | 442篇 |
2008年 | 716篇 |
2007年 | 711篇 |
2006年 | 739篇 |
2005年 | 612篇 |
2004年 | 590篇 |
2003年 | 492篇 |
2002年 | 455篇 |
2001年 | 140篇 |
2000年 | 124篇 |
1999年 | 144篇 |
1998年 | 162篇 |
1997年 | 122篇 |
1996年 | 110篇 |
1995年 | 89篇 |
1994年 | 98篇 |
1993年 | 75篇 |
1992年 | 108篇 |
1991年 | 106篇 |
1990年 | 102篇 |
1989年 | 110篇 |
1988年 | 109篇 |
1987年 | 97篇 |
1986年 | 86篇 |
1985年 | 90篇 |
1984年 | 72篇 |
1983年 | 54篇 |
1982年 | 48篇 |
1981年 | 59篇 |
1980年 | 50篇 |
1979年 | 50篇 |
1978年 | 43篇 |
1977年 | 42篇 |
1976年 | 49篇 |
1975年 | 40篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
41.
Ana P Martinez-Donate Melbourne F Hovell Elaine J Blumberg Jennifer A Zellner Carol L Sipan Audrey M Shillington Claudia Carrizosa 《AIDS education and prevention》2004,16(2):172-186
Adolescents are at increasing risk for HIV infection in Mexico. Research on gender differences in risk behaviors and determinants is needed to develop effective HIV prevention interventions targeting Mexican adolescents. This study examined gender differences in the likelihood of unprotected sex and theoretical correlates among high school students in the border city of Tijuana. Three hundred seventy high-school students completed a face-to-face interview and a self-administered survey. Differences in sexual initiation, condom use, intentions to use condoms in the future, and attitudes towards condoms in this population were assessed. Although male students initiated sexual practices earlier than females, females were more likely to have unprotected sex. Females perceived themselves as more likely to avoid unprotected sex in the future and held more favorable attitudes about condoms. The results suggest that stereotypical gender roles and communication barriers place Tijuana female high school students at higher risk for HIV infection than their male peers. 相似文献
42.
43.
Christopher L. Hansen Richard A. Goldstein Olakunle O. Akinboboye Daniel S. Berman Elias H. Botvinick Keith B. Churchwell C. David Cooke James R. Corbett S. James Cullom Seth T. Dahlberg Regina S. Druz Edward P. Ficaro James R. Galt Ravi K. Garg Guido Germano Gary V. Heller Milena J. Henzlova Mark C. Hyun Lynne L. Johnson April Mann Benjamin D. McCallister Robert A. Quaife Terrence D. Ruddy Senthil N. Sundaram Raymond Taillefer R. Parker Ward John J. Mahmarian 《Journal of nuclear cardiology》2007,14(6):e39-e60
44.
45.
Intestinal schistosomiasis japonica: CT-pathologic correlation 总被引:1,自引:0,他引:1
Lee RC; Chiang JH; Chou YH; Rubesin SE; Wu HP; Jeng WC; Hsu CC; Tiu CM; Chang T 《Radiology》1994,193(2):539
46.
Mitsuhiro Denda Barbara E. Brown Peter M. Elias K. R. Feingold 《Archives of dermatological research》1997,289(2):104-110
Isoprenylation is the covalent attachment of isoprenyl groups, intermediates of the cholesterol biosynthesis pathway, to carboxy
terminal cysteine residues of proteins. Numerous proteins are isoprenylated including small GTP binding proteins, trimeric
G proteins, and nuclear lamins, and these prenylated proteins regulate a variety of cell functions, including cell growth,
cytokinesis, and differentiation. Here, we quantitated protein prenylation and determined which proteins are prenylated in
the epidermis of hairless mice by radiolabeling with
3
H-mevalonolactone following acute or chronic epidermal injury. In normal epidermis, four major radiolabeled bands, with molecular
weights of 17–26, 48, 54, and 68 kDa, were observed. The levels of each of these bands increased by 24–63% 16 h following
acute epidermal injury induced by topical acetone treatment or tape stripping, returning to normal by 24 h. On 2D gel electrophoresis,
there were no major differences between the patterns of labeling following barrier disruption. Subacute epidermal injury induced
by either acetone or tape stripping twice a day for 7 days and chronic injury induced by feeding an essential fatty acid-deficient
(EFAD) diet, also resulted in a significant increase in protein prenylation. As with acute injury, SDS-PAGE and 2D gel electrophoresis
did not reveal marked differences in the pattern of protein prenylation. These results demonstrate that the prenylation of
proteins in the epidermis is stimulated by injury, suggesting that one or more of these prenylated species may be important
in epidermal proliferation or differentiation.
Received: 29 May 1996 相似文献
47.
S R Levine I M Diaczok M J Deegan S N Kieran H Feit S B Elias K M Welch 《Archives of neurology》1987,44(6):678-679
A 44-year-old woman developed recurrent thrombotic cerebral cortical infarctions. IgG and IgM anticardiolipin antibodies were found, as was a thymoma. To our knowledge, these antiphospholipid antibodies, which may inhibit prostacyclin formation and alter platelet function, have not been previously associated with this thymic neoplasm, an association we believe is not coincidental. 相似文献
48.
Prevalence of Hepatitis A, B, and C markers in school children of a rural area of Crete, Greece 总被引:2,自引:0,他引:2
Christos Lionis Effie Frangoulis Maria Koulentakis Evangelos Biziagos Elias Kouroumalis 《European journal of epidemiology》1997,13(4):417-420
Objective: To determine the prevalence of hepatitis A, B, and C markers in children who were attending junior and senior high schools in a high risk area in rural Crete, Greece. Methods: Three-hundred and thirty-four children who attended the three junior schools and one senior high school in the Agios Vassilios province of Southern Crete were invited to participate in the study. Three hundred and four of them were tested for hepatitis A, B, and C markers. Hepatitis B (HBV) markers (HBsAg and anti-HBc) as well as hepatitis A (anti-HAV) and hepatitis (anti-HCV) antibodies were tested with commercial enzyme-linked immunosorbent assay kits. Results: Six of the 304 children (1.97%) were found to be positive for anti-HAV, 1 (0.33%) to HBsAg, 7 (2.30%) to anti-HBc and none were found positive for anti-HCV. No significant differences were seen between the prevalence of anti-HAV antibodies in males (2%) and females (1.95%), and of anti-HBc antibodies in males (3.33%) and females (1.30%). Conclusions: The very low prevalence of anti-HAV is obviously due to the improved conditions of hygiene and it raises the question of the possible emergence of this disease at an older age and therefore appropriate preventative strategies should be considered. The low endemicity of hepatitis B in Crete in contrast to other areas of Greece also calls for a vaccination policy probably during adolescence. The absence of hepatitis C markers in the children in contrast to the observed higher prevalence of HCV-infected people in the adult population in the same rural area raises questions regarding possible sources of transmission of hepatitis C during the preceding years. 相似文献
49.
Daniel L. Rubin Karen L. Falk Malcolm J. Sperling Michael Ross Sanjay Saini Barry Rothman Frank Shellock Elias Zerhouni David Stark Eric K. Outwater Udo Schmiedl Louis C. Kirby Judith Chezmar Terry Coates Miles Chang Jeffery M. Silverman Neil Rofsky Keith Burnett Julie Engel Stuart W. Young 《Journal of magnetic resonance imaging : JMRI》1997,7(5):865-872
The purpose of this study was to assess the effectiveness and safety of Gadolite Oral Suspension as a gastrointestinal (GI) contrast agent for MRI in a phase II and two phase III multicenter clinical trials. Gadolite was administered to 306 patients with known or suspected abdominal and/or pelvic disease. MRI with T1- and T2-weighted sequences was performed before and after ingestion. Efficacy was evaluated by having two masked readers rate the certainty of their MR diagnosis (0 = uncertain, 1 = probable, 2 = definite) on randomly presented pre- and post-Gadolite Oral Suspension enhanced images. Principal investigators also evaluated the images and established the final diagnosis. Vital signs, clinical chemistries, and adverse events were documented. Blood and urine samples were analyzed for gadolinium content to determine whether Gadolite Oral Suspension was absorbed systemically. Certainty in MR diagnosis increased significantly (P < .001) for both blinded readers between pre- and post-Gadolite images (.49–1.18 for reader 1; .46–1.53 for reader 2). Sensitivity, specificity, and accuracy also increased for both masked readers. No gadolinium was detected in blood or urine samples. There were no serious adverse events and no apparent drug-related trends in mean vital signs or laboratory values. Gadolite is a highly effective, safe, and well tolerated contrast agent for clinical use with MRI. 相似文献
50.
Interobserver variability in neonatal cranial ultrasonography 总被引:1,自引:0,他引:1
Jennifer Pinto Nigel Paneth Elias Kazam Ram Kairam Sylvan Wallenstein Walter Rose David Rosenfeld Steven Schonfeld Irving Stein Thomas Witomski 《Paediatric and perinatal epidemiology》1988,2(1):43-58
The reliability of cranial ultrasound diagnosis in the premature neonate was examined using data from an ongoing multicentre study of the epidemiology and long-term consequences of neonatal brain haemorrhage. First week ultrasound films (obtained at 4 hours, 24 hours and 7 days) from 60 study subjects were randomly selected for independent review by two groups of experienced interpreters, and results were recorded separately for observations (i.e. presence or absence of an abnormal echodense area on a film) and interpretations (i.e. presence or absence of haemorrhage or ventricular dilatation) in each hemisphere. Because of deaths in the first week of life, the total number of films examined was 138. Concordance on the presence or absence of an abnormal echodensity was examined for each individual film for three areas of interest: the germinal matrix, the ventricles and the parenchyma. Concordance on the presence or absence of haemorrhage or ventricular dilatation was examined only for the seventh-day film, or the final film prior to death. Finally, concordance was analysed with the diagnostic interpretations grouped into categories thought to differ prognostically for long-term outcome. In general, concordance was poorest for germinal matrix lesions and best for parenchymal lesions. Concordance was lower for observations made on each individual film than it was for interpretation of the final film in each case. Fifty-five of 60 cases (92%) were assigned to the same major prognostic category by both readers. Ultrasound review conferences were held periodically and there was evidence that concordance in ultrasound reading and interpretation improved during the course of the study. 相似文献