全文获取类型
收费全文 | 8857篇 |
免费 | 886篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 389篇 |
妇产科学 | 246篇 |
基础医学 | 933篇 |
口腔科学 | 189篇 |
临床医学 | 1134篇 |
内科学 | 1631篇 |
皮肤病学 | 82篇 |
神经病学 | 760篇 |
特种医学 | 526篇 |
外科学 | 1358篇 |
综合类 | 175篇 |
一般理论 | 2篇 |
预防医学 | 1004篇 |
眼科学 | 176篇 |
药学 | 552篇 |
中国医学 | 4篇 |
肿瘤学 | 551篇 |
出版年
2023年 | 75篇 |
2021年 | 106篇 |
2020年 | 102篇 |
2019年 | 113篇 |
2018年 | 168篇 |
2017年 | 118篇 |
2016年 | 134篇 |
2015年 | 156篇 |
2014年 | 223篇 |
2013年 | 356篇 |
2012年 | 319篇 |
2011年 | 377篇 |
2010年 | 218篇 |
2009年 | 212篇 |
2008年 | 342篇 |
2007年 | 390篇 |
2006年 | 382篇 |
2005年 | 320篇 |
2004年 | 322篇 |
2003年 | 278篇 |
2002年 | 270篇 |
2001年 | 303篇 |
2000年 | 306篇 |
1999年 | 289篇 |
1998年 | 187篇 |
1997年 | 171篇 |
1996年 | 163篇 |
1995年 | 137篇 |
1994年 | 135篇 |
1993年 | 113篇 |
1992年 | 206篇 |
1991年 | 190篇 |
1990年 | 209篇 |
1989年 | 186篇 |
1988年 | 188篇 |
1987年 | 159篇 |
1986年 | 175篇 |
1985年 | 165篇 |
1984年 | 144篇 |
1983年 | 117篇 |
1982年 | 87篇 |
1981年 | 89篇 |
1980年 | 63篇 |
1979年 | 114篇 |
1978年 | 74篇 |
1977年 | 76篇 |
1975年 | 80篇 |
1974年 | 74篇 |
1973年 | 77篇 |
1972年 | 62篇 |
排序方式: 共有9776条查询结果,搜索用时 15 毫秒
71.
D. S. Dunn A. V. Romphruk C. Leelayuwat M. Bellgard J. K. Kulski 《Annals of human genetics》2005,69(4):364-372
Polymorphic Alu insertions (POALINs) are known to contribute to the strong polymorphic nature of the Major Histocompatibility Complex (MHC). Previous population studies on MHC POALINs were limited to only Australian Caucasians and Japanese. Here, we report on the individual insertion frequency of the five POALINs within the MHC class I region, their HLA‐A and ‐B associations, and the three and four locus alpha block POALIN haplotype frequencies in the Northeastern (NE) Thai population. Of the five POALINs, the lowest frequency was 0.018 for AluyHF and the highest frequency was 0.292 for AluyHJ and AluyHG. The strongest positive associations between the POALINs and HLA class I alleles was between AluyMICB and HLA‐B*57, AluyHJ and HLA‐A*24 and HLA‐A*01, and AluyHG and HLA‐A*02, supporting previous findings in Caucasians and Japanese. Single POALIN haplotypes were found more frequently than multiple POALIN haplotypes. However, of the seven different POALIN haplotypes within the MHC alpha block, there were only two significant differences between the NE Thais, Caucasians and Japanese. This study confirms that the MHC POALINs are in linkage disequilibrium with HLA‐A and –B alleles and that there are significant frequency differences for some of the POALINs when compared between NE Thai, Caucasians and Japanese. 相似文献
72.
R. G. Schaub C. J. Dunn M. R. Deibel A. E. Berger D. Wunderlich W. E. Fleming 《Inflammation research》1990,31(1-2):127-134
Human leukocyte suspensions (neutrophils 80–85%, monocyte 15–20%) were incubated alone or with cultured human umbilical vein endothelial cells. Leukocytes were either directly added to the endothelial cell cultures or separated from them by a 0.4 micron insert filter. Supernatants or cell lysates were obtained at 0.5, 1, 2, and 4 hours of incubation. Supernatants were assayed for the prostacyclin (PGI2) metabolite 6-keto prostaglandin F1 and prostaglandin E2 (PGE2) by radioimmunoassay and for interleukin-1 (IL-1) by the thymocyte co-mitogen assay. Cell lysates were analyzed for cell-associated procoagulant activity (PCA). Co-incubation of endothelial cells with leukocytes stimulated the synthesis of PGI2, PGE2, and PCA. These biochemical changes correlated partially with the release of IL-1 beta. The results suggest that IL-1 released in monocyte/neutrophil co-cultures can produce prothrombotic (increased PCA expression) and inflammatory changes (increased synthesis of vasodilatory and permeability enhancing PGI2 and PGE2) in endothelial cells. Neutrophils may represent a source of the released IL-1 and/or may act to stimulate monocyte release of this cytokine and thus play an important role in vascular pathology by a mechanism unrelated to their more direct cytotoxic activity. 相似文献
73.
Two-dimensional gel electrophoresis and immunoblotting of Campylobacter pylori proteins. 总被引:10,自引:5,他引:10 下载免费PDF全文
Whole-cell, outer-membrane protein, flagellum-associated antigens and partially purified urease of Campylobacter pylori were analyzed by two-dimensional gel electrophoresis. C. pylori strains were readily distinguished from strains of Campylobacter jejuni, C. coli, and C. fetus by absence of major outer membrane proteins with Mrs of 41,000 to 45,000. C. pylori strains also lacked the acidic surface-array proteins at Mr 100,000 to 149,000 identified previously in serum-resistant strains of C. fetus. Surface labeling of intact C. pylori cells with 125I revealed two common major proteins, which we have designated protein 2 (pI 5.6 to 5.8, Mr 66,000) and protein 3 (pI 5.2 to 5.5, Mr 63,000). Proteins 2 and 3 were also the major components (subunits) observed in partially purified urease. Partially purified preparations of flagella consistently contained proteins 2 and 3. Thus, urease appears to be associated with both outer membranes and flagella of C. pylori. C. pylori strains also possessed an antigen at Mr 59,000 which was cross-reactive with antiserum against flagella of C. jejuni. However, the antigen did not appear to be associated with flagella per se in C. pylori. Protein 2 was unique to C. pylori among the Campylobacter species studied. It was not recognized by antibody against whole cells of C. jejuni or C. fetus or flagella of C. jejuni. Protein 3 was cross-reactive with antiserum against whole cells of C. jejuni and C. fetus, as were several other major protein antigens. Because protein 2 is a major outer membrane protein that is apparently unique to C. pylori, development of monospecific antibodies against this antigen may be useful for the identification of C. pylori in tissues, and purified antigen may be useful for serologic tests for specific diagnosis of C. pylori infections. 相似文献
74.
Serotypic and genotypic characterization of human serotype 10 rotaviruses from asymptomatic neonates. 总被引:2,自引:7,他引:2 下载免费PDF全文
S J Dunn H B Greenberg R L Ward O Nakagomi J W Burns P T Vo K A Pax M Das K Gowda C D Rao 《Journal of clinical microbiology》1993,31(1):165-169
Human rotaviruses were isolated from asymptomatic neonates at various hospitals and clinics in the city of Bangalore, India, and were found to be subgroup I specific and possess long RNA patterns (M. Sukumaran, K. Gowda, P. P. Maiya, T. P. Srinivas, M. S. Kumar, S. Aijaz, R. R. Reddy, L. Padilla, H. B. Greenberg, and C. D. Rao, Arch. Virol. 126:239-251, 1992). Three of these strains were adapted to tissue culture and found by serotype analysis and neutralization assays to be of serotype 10, a serotype commonly found in cattle but infrequently found in humans and not previously identified in neonates. By RNA-RNA hybridization, a high level of relatedness to a serotype 10 bovine rotavirus strain and a low-to-medium level of relatedness to a human rotavirus strain were observed. Since this human isolate shares a genogroup with bovine rotavirus, it is likely that it originated by interspecies transmission. A human rotavirus strain isolated from asymptomatic neonates and similar to bovine rotavirus might represent a good vaccine candidate. 相似文献
75.
Striated intramural gallbladder lucencies on US studies: predictors of acute cholecystitis 总被引:1,自引:0,他引:1
Ultrasound scans of 51 consecutive patients with gallbladder wall thickening were reviewed, and specific sonographic features were correlated with surgical and clinical follow-up. Two patterns of thickening were identified as specific indicators of the presence or absence of acute cholecystitis. "Striated" wall thickening, consisting of several alternating, irregular, discontinuous, lucent and echogenic bands, was seen in eight of 13 patients (62%) with acute cholecystitis. This pattern was not encountered in any of the patients who did not have acute cholecystitis. Conversely, "three-layer" thickening, consisting of a single circumferential lucent zone between two relatively uniform echogenic layers, was seen in only one of 13 patients (8%) with acute cholecystitis but in 11 of 38 patients (29%) with other diagnoses. Other abnormalities, including the presence of intramural echogenic foci and wall irregularities, were more frequently seen in patients with acute cholecystitis but were not as helpful. Use of these features may suggest or help exclude a diagnosis of acute cholecystitis in those patients in whom the cause of gallbladder wall thickening is otherwise not apparent. 相似文献
76.
Exfoliated mucosal cells were collected from the oral cavityof three groups at high risk for oral cancer: Indian betel nutchewers, Filipino inverted smokers (burning end of cigar inmouth) and Indian Khaini tobacco chewers. DNA was extractedfrom these samples, as well as from samples of exfoliated cellsof Canadian non-smoking controls. DNA was analyzed for the presenceof aromatic DNA adducts using 32P-postlabel-ling analysis. Fivechromatographically distinct adducts were found in samples fromboth the high risk groups and the nonsmoking controls. Individualadducts were detectable in 3095% of samples, dependingon the adduct and population group. Estimated levels of specificadducts ranged from non-detectable (prevalence relative to normalnucleotides < 1 x 10-9) to occasionally > 1x 10-7. Noadducts were found in high risk groups which did not also appearin control subjects. 相似文献
77.
Dunn Jennifer A. Hackney Jonathan J. Martin Rachelle A. Tietjens Donna Young Timothy Bourke John A. Snell Deborah L. Nunnerley Joanne L. Hall Andrew Derrett Sarah 《Journal of occupational rehabilitation》2021,31(4):730-743
Journal of Occupational Rehabilitation - Purpose Little is currently known about how early intervention vocational rehabilitation (EIVR) works for people with newly acquired neurological conditions... 相似文献
78.
79.
Modupeola Diyaolu Anne-Laure Thomas Lauren SY Wood Jordan Taylor James CY Dunn 《Journal of pediatric surgery》2021,56(1):5-10
BackgroundShort gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis.MethodsFemale juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature.ResultsA statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ± 0.7 vessels, after: 4.7 ± 1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ± 3.0 vessels/mm, spring: 7.0 ± 9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ± 3.0 vessels/mm, spring: 8.0 ± 8.0 vessels/mm, p = 0.003).ConclusionIntestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine.Level of evidenceN/AType of studyTreatment study. 相似文献