全文获取类型
收费全文 | 32573篇 |
免费 | 2248篇 |
国内免费 | 117篇 |
专业分类
耳鼻咽喉 | 244篇 |
儿科学 | 1078篇 |
妇产科学 | 638篇 |
基础医学 | 4390篇 |
口腔科学 | 905篇 |
临床医学 | 3312篇 |
内科学 | 6377篇 |
皮肤病学 | 412篇 |
神经病学 | 3502篇 |
特种医学 | 1163篇 |
外国民族医学 | 6篇 |
外科学 | 4583篇 |
综合类 | 394篇 |
一般理论 | 52篇 |
预防医学 | 2390篇 |
眼科学 | 1206篇 |
药学 | 2307篇 |
中国医学 | 51篇 |
肿瘤学 | 1928篇 |
出版年
2022年 | 202篇 |
2021年 | 428篇 |
2020年 | 274篇 |
2019年 | 444篇 |
2018年 | 541篇 |
2017年 | 450篇 |
2016年 | 489篇 |
2015年 | 548篇 |
2014年 | 765篇 |
2013年 | 1280篇 |
2012年 | 1952篇 |
2011年 | 2137篇 |
2010年 | 1158篇 |
2009年 | 1120篇 |
2008年 | 2047篇 |
2007年 | 2325篇 |
2006年 | 2214篇 |
2005年 | 2244篇 |
2004年 | 2152篇 |
2003年 | 2134篇 |
2002年 | 2030篇 |
2001年 | 299篇 |
2000年 | 241篇 |
1999年 | 309篇 |
1998年 | 460篇 |
1997年 | 411篇 |
1996年 | 317篇 |
1995年 | 336篇 |
1994年 | 323篇 |
1993年 | 314篇 |
1992年 | 237篇 |
1991年 | 222篇 |
1990年 | 191篇 |
1989年 | 165篇 |
1988年 | 172篇 |
1987年 | 173篇 |
1986年 | 205篇 |
1985年 | 196篇 |
1984年 | 311篇 |
1983年 | 288篇 |
1982年 | 357篇 |
1981年 | 320篇 |
1980年 | 330篇 |
1979年 | 173篇 |
1978年 | 202篇 |
1977年 | 207篇 |
1976年 | 131篇 |
1975年 | 141篇 |
1974年 | 125篇 |
1973年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
33.
Ronald G. Pratt Jie Zheng Brent K. Stewart Yoseph Shiferaw Anthony J. McGoron Ranasinghage C. Samaratunga Stephen R. Thomas 《Magnetic resonance in medicine》1997,37(2):307-313
A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO2) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The pO2 measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O2) which reduces the PFC 19F T1? Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of 19F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of 19F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated pO2 maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat. 相似文献
34.
Ronald D. Curran M.D. Constantine Mavroudis M.D. Carl L. Backer M.D. 《Journal of cardiac surgery》1997,12(6):372-379
A bstract Background : Ventricular-to-pulmonary artery conduits in growing patients with congenital heart disease will require replacement from time to time due to somatic growth, neointimal hyperplasia, and pulmonary artery stenosis. The purpose of this article is to review our experience with ascending aortic extension for significant long-segment pulmonary artery stenosis in patients undergoing reoperation for right ventricular-to-pulmonary artery conduit replacement. Methods : From 1989 to 1997, 8 patients had aortic transection, right pulmonary artery augmentation arterioplasty, and aortic interposition graft (Hemashield in 7 and Gore-tex in 1) in association with right ventricular-to-pulmonary artery conduit replacement in 7 patients and completion Fontan operation in 1 patient. Aortic cross-clamp time was 90 ± 34 minutes, and the cardiopulmonary bypass time was 205 ± 37 minutes. Results : All patients survived. In those 7 patients who had conduit replacement, the RV/LV ratio declined from 0.78 ± 0.15 to 0.45 ±; 0.05 postoperatively (P < 0.05). Average length of stay was 8.9 ± 7.2 days. Follow-up range is 18 months to 8 years (mean 4 years). Two complications included cardiac transplantation for pre-existing poor left ventricular function and accelerated conduit stenosis leading to conduit re-replacement. Conclusion : Ascending aortic extension facilitates long-segment pulmonary artery augmentation arterioplasty and enlarges the retroaortic space, preventing future compression restenosis. 相似文献
35.
Mark C. K. Yang Ronald G. Marks William B. Clark Ingvar Magnusson 《Journal of clinical periodontology》1992,19(2):77-83
Abstract Several statistical models that have been suggested in the periodontal literature for describing longitudinal attachment level changes, such as the gradual loss, single-burst, multiple-burst, and random walk models as well as other models introduced in this paper are compared by their power to predict future attachment loss. The data used in this analysis is from 1061 sites of 8 subjects, with moderate to severe periodontal disease, monitored monthly for about a year. This study found that none of the suggested models could significantly outperform the naive mean predictor, which predicts the future attachment level from the past mean. It was also found that no single model, such as the burst, gradual, or random walk, together with measurement error can fully explain the variation in the data. These results indicate that in the course of one year, the attachment level change may not follow the same model. Consequently, a model that fits well to past data cannot be accurately extended to the future. 相似文献
36.
37.
Editorial comment 总被引:2,自引:0,他引:2
Ronald Dubner Howard L. Fields Gerald F. Gebhart John D. Loeser Harold Merskey Patrick D. Wall 《Pain》1992,50(3):247-248
38.
Ronald R. Watson PhD Mary E. Mohs MS RD Cteamond Eskelson PhD Richard E. Samptiner MD Barbara Hartmann PhD 《Alcoholism, clinical and experimental research》1986,10(4):364-385
The prevalence and incidence of heavy alcohol consumption are major problems which have been increasing in many countries in recent years. It is crucial for physicians to consistently identify early drinking problems as well as the various end disease states in order to minimize suffering and maximize recovery. This paper reviews the evolutionary development of clinical tools for detection of alcohol abuse. The focus is primarily on clinical/biochemical indicators of alcohol abuse, emphasizing but not limited to changes in hematological characteristics, liver enzyme activity, lipids, immune function factors, hormones, neurological factors, and some physically based tests. Use of test combinations and sophisticated statistical analysis of pattern changes in test batteries evidence increased diagnostic efficiency. 相似文献
39.
Sequence-specific DNA binding of individual cut repeats of the human CCAAT displacement/cut homeodomain protein. 总被引:14,自引:0,他引:14 下载免费PDF全文
B Aufiero E J Neufeld S H Orkin 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(16):7757-7761
CCAAT displacement protein (CDP), a nuclear protein of 180-190 kDa, contains a triplicated motif, the cut domain, similar (80-90% conserved) to three repeats of 60-65 amino acids first identified in Drosophila cut, a homeo-domain protein involved in cell-fate decisions in development. Cut repeats bind DNA and exhibit subtle differences in target-site recognition. DNA sequences specifically bound by cut repeats were isolated by PCR-mediated DNA target-site selection. Sequences selected for cut repeat 2 and 3 (CR2 and CR3) binding are A+T-rich and favor an ATA motif with similar, but not identical, flanking base preferences. CR2 and CR3 discriminate among similar target sequences. CR1, which is more divergent from CR2 and CR3, displays the most restricted pattern of DNA sequence recognition. Methylation interference analysis demonstrates different protein-DNA contacts for CR1 and CR3 binding to a target sequence. Thus, CDP/cut is a complex protein whose DNA-binding properties reflect the combinatorial interaction of four domains (three cut repeats and one homeodomain) with target DNA sequences. 相似文献
40.
Chronic recurrent multifocal osteomyelitis and psoriasis—A report of a new association and review of related disorders 总被引:3,自引:0,他引:3
Ronald M. Laxer MDCM FRCPC Assistant Professor Abraham D. Shore MD FRCPC Assistant Professor David Manson MD Chief Resident Susan King MD FRCPC Fellow Earl D. Silverman MD FRCPC Assistant Professor Dan M. Wilmot MD FRCPC Assistant Professor 《Seminars in arthritis and rheumatism》1988,17(4):260-270
In summary, we have described two patients with CRMO and psoriasis, and have reviewed the musculoskeletal manifestations associated with pustular eruptions of the palms and soles. In view of the frequent occurrence of PPP in patients with CRMO, we suggest that the occurrence of psoriasis in our two patients is more than coincidence, and that noninfectious, inflammatory lesions of bone may be another musculoskeletal manifestation of psoriasis. This rare association, as well as the association of PPP with disorders associated with new bone formation, may shed new insights on the relatively common finding of periosteal elevation associated with psoriatic arthritis and the occasional severe juxta-articular osteolytic destructive bone lesions seen in psoriatic arthritis. 相似文献