全文获取类型
收费全文 | 1592篇 |
免费 | 114篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 93篇 |
妇产科学 | 17篇 |
基础医学 | 191篇 |
口腔科学 | 17篇 |
临床医学 | 135篇 |
内科学 | 316篇 |
皮肤病学 | 42篇 |
神经病学 | 40篇 |
特种医学 | 139篇 |
外国民族医学 | 1篇 |
外科学 | 172篇 |
综合类 | 176篇 |
预防医学 | 98篇 |
眼科学 | 12篇 |
药学 | 121篇 |
中国医学 | 3篇 |
肿瘤学 | 124篇 |
出版年
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 40篇 |
2020年 | 16篇 |
2019年 | 40篇 |
2018年 | 35篇 |
2017年 | 36篇 |
2016年 | 32篇 |
2015年 | 44篇 |
2014年 | 58篇 |
2013年 | 68篇 |
2012年 | 100篇 |
2011年 | 79篇 |
2010年 | 69篇 |
2009年 | 63篇 |
2008年 | 94篇 |
2007年 | 72篇 |
2006年 | 46篇 |
2005年 | 67篇 |
2004年 | 49篇 |
2003年 | 52篇 |
2002年 | 59篇 |
2001年 | 47篇 |
2000年 | 23篇 |
1999年 | 31篇 |
1998年 | 55篇 |
1997年 | 42篇 |
1996年 | 34篇 |
1995年 | 24篇 |
1994年 | 30篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 35篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 21篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1971年 | 3篇 |
排序方式: 共有1726条查询结果,搜索用时 0 毫秒
1.
Akira Sawaki Nobumasa Mizuno Kuniyuki Takahashi Tsuneya Nakamura Masahiro Tajika Hiroki Kawai Toshifumi Isaka Hiroshi Imaoka Yasuyuki Okamoto Masatoshi Aoki Hiroyuki Inoue Ahmed AS Salem Yasushi Yatabe Kenji Yamao 《Digestive endoscopy》2006,18(1):40-44
Background: Gastrointestinal stromal tumors (GIST) are one of the most common mesenchymal tumors of the gastrointestinal tract. GIST are defined by positive immunohistochemical staining for KIT or CD34 and thus are generally diagnosed after surgery. Because small GIST are rarely diagnosed before surgery, the clinical course of these small tumors is not clear. The aim of the present study was to follow changes in size and configuration of small GIST that were pathologically confirmed using endoscopic ultrasonography‐guided fine‐needle aspiration biopsy (EUS‐FNAB). Methods: Between July 1997 and December 2003, 16 tumors in 16 patients (10 men and 6 women) with an immunohistochemical diagnosis of GIST were regularly followed in our hospital. The median patient age when EUS‐FNAB was performed was 62 years (range 26–82 years) and the median follow‐up period was 4.9 years (range 0.5–9.6 years). Results: Fourteen tumors showed no remarkable changes in size and shape during follow up compared with the initial diagnosis. Two tumors enlarged: one tumor approximately doubled its diameter in 8 years and the other tumor increased from 1.8 cm at diagnosis to up to 10 cm after only 2 years. Doubling time of the latter tumor was calculated as 3.1 months. Conclusions: We conclude that EUS‐FNAB might be a good modality for final diagnosis of GIST without surgery, and that GIST without rapid growth on follow up can be endoscopically followed. 相似文献
2.
Coronary artery bypass grafts: visualization with MR imaging 总被引:1,自引:0,他引:1
3.
4.
5.
Pulmonary diseases in patients infected with the human immunodeficiency virus in Zimbabwe, Central Africa 总被引:2,自引:0,他引:2
D T McLeod P Neill V J Robertson A S Latif J C Emmanuel J E Els L K Gwanzura F E Trijssenaar P Nziramasanga G R Jongeling 《Transactions of the Royal Society of Tropical Medicine and Hygiene》1989,83(5):694-697
During the 11 month period up to 30 September 1987, 37 patients (26 male, 11 female, mean age 27 years) with respiratory symptoms who were human immunodeficiency virus (HIV) positive, were studied prospectively on 40 occasions to determine the cause of any pulmonary complications. HIV was heterosexually transmitted. Predominant symptoms were cough (89%), fever (89%), weight loss (83%), and dyspnoea (60%). Transnasal fibre-optic bronchoscopy (with bronchoalveolar lavage, bronchial brushings and transbronchial lung biopsies) was performed on 35 patients, twice on 3 patients. 'Tru-cut' lung biopsies were obtained from 2 patients who died before bronchoscopy. Pulmonary tuberculosis was the commonest disease, being found in one-third of the patients (12 of 37). Mycobacterium tuberculosis was cultured from 4; the remainder of the plates were contaminated. Pneumocystis carinii was present in 8 patients: as the sole pathogen in 3, with Streptococcus pneumoniae in 4, Staphylococcus aureus in 2, and one also had tuberculous lymphadenitis. Endobronchial Kaposi's sarcoma was seen in 6 of 7 patients with skin nodules. Bacterial pathogens isolated included Staph. aureus (5), S. pneumoniae (5), Klebsiella pneumoniae (2), Haemophilus influenzae (2), H. parainfluenzae (1) and Pseudomonas aeruginosa (1). Invading Aspergillus fumigatus was diagnosed by lung biopsy in one. No diagnosis was reached for 8 patients. It is concluded that in Central Africa pulmonary complications in AIDS patients are similar to those in Europe and North America but the incidence of different pathogens depends on the prevalence of pathogens in the community. M. tuberculosis is probably the commonest pathogen. This study has confirmed that P. carinii pneumonia does occur, but occurs less frequently. 相似文献
6.
7.
Tick-susceptible Friesian steers were used as bait animals to assess the availability of adult Rhipicephalus appendiculatus Neumann on the pasture. Assuming that initial gross pickup rates of ticks by cattle were similar, the numbers of female ticks that attached and the numbers that subsequently fed to maturity on individual cattle were compared based on data obtained from bait animals. The proportion of successful attachments on high-resistance (HR) cattle (0.30) was significantly less than that on the low-resistance (LR) animals (0.51). Similarly, the proportion of attached ticks that fed to maturity also was significantly lower on HR animals (0.15) than on LR animals (0.33). Female survival was calculated as the product of these two parameters. On the HR cattle, female survival (0.05) was significantly less than on LR (0.18). About 12% of the cattle had low resistance, and up to 73% of the females survived on them. These animals were responsible for much of the tick multiplication in the field population. 相似文献
8.
9.
Competitive control of the self-renewing T cell repertoire 总被引:1,自引:0,他引:1
We develop a mathematical model for the self-renewing part of the T cell
repertoire. Assuming that self-renewing T cells have to be stimulated by
immunogenic MHC-peptide complexes presented on the surfaces of
antigen-presenting cells, we derive a model of T cell growth in which
competition for MHC-peptide complexes limits T cell clone sizes and
regulates the total number of self-renewing T cells in the animal. We show
that for a sufficient diversity and/or degree of cross-reactivity, the
total T cell number hardly depends upon the diversity of the T cell
repertoire or the diversity of the set of presented peptides. Conversely,
for repertoires of lower diversity and/or cross-reactivity, steady-state
total T cell numbers may be limited by the diversity of the T cells. This
provides a possible explanation for the limited repertoire expansion in
some, but not all, mouse T cell re-constitution experiments. We suggest
that the competitive interactions described by our model underlie the
normal T cells numbers observed in transgenic mice, germ-free mice and
various knockout mice.
相似文献
10.
The effect of surface sugars of liposomes on the immunological responses to entrapped antigen has been investigated. alpha-Mannose and beta-galactose were grafted on the surface of liposomes containing lysozyme by covalent coupling of p-aminophenyl-D-glycosides to phosphatidyl ethanolamine liposomes using glutaraldehyde. Subcutaneous administration of antigen entrapped in beta-galactose liposomes stimulated an antibody response comparable to that elicited by sugar-free neutral liposomes. However, alpha-mannose bearing liposomes with entrapped lysozyme elicited an immune response similar to that induced by lysozyme in saline. Based on these observations it is suggested that alpha-mannose liposomes, that are specifically recognized by macrophages, are taken up rapidly by receptor mediated endocytosis and that the entrapped antigen is then rapidly degraded, resulting in low antibody production. 相似文献