首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8108篇
  免费   1127篇
  国内免费   506篇
耳鼻咽喉   128篇
儿科学   27篇
妇产科学   208篇
基础医学   1280篇
口腔科学   374篇
临床医学   452篇
内科学   781篇
皮肤病学   81篇
神经病学   412篇
特种医学   179篇
外国民族医学   5篇
外科学   1046篇
综合类   1298篇
现状与发展   2篇
预防医学   144篇
眼科学   67篇
药学   439篇
  1篇
中国医学   194篇
肿瘤学   2623篇
  2024年   34篇
  2023年   180篇
  2022年   435篇
  2021年   545篇
  2020年   461篇
  2019年   391篇
  2018年   359篇
  2017年   424篇
  2016年   433篇
  2015年   565篇
  2014年   598篇
  2013年   550篇
  2012年   501篇
  2011年   516篇
  2010年   362篇
  2009年   402篇
  2008年   391篇
  2007年   326篇
  2006年   319篇
  2005年   287篇
  2004年   248篇
  2003年   173篇
  2002年   166篇
  2001年   138篇
  2000年   118篇
  1999年   115篇
  1998年   100篇
  1997年   81篇
  1996年   77篇
  1995年   69篇
  1994年   71篇
  1993年   47篇
  1992年   35篇
  1991年   34篇
  1990年   28篇
  1989年   17篇
  1988年   19篇
  1987年   18篇
  1986年   12篇
  1985年   21篇
  1984年   14篇
  1983年   6篇
  1982年   17篇
  1981年   9篇
  1980年   12篇
  1979年   5篇
  1978年   2篇
  1977年   6篇
  1976年   2篇
  1967年   1篇
排序方式: 共有9741条查询结果,搜索用时 234 毫秒
11.
12.
Small bowel transplantation (SBT) is associated with poorly understood enteric dysfunction. The study of SBT in mice is hindered by the technical difficulty of orthotopic SBT in the mouse. Our aim was to develop an easy preparation of extrinsic denervation of the entire jejunoileum in mice as a model of orthotopic SBT. All neurolymphatic tissues accompanying the superior mesenteric artery (SMA) and vein (SMV) were ligated just distal to the middle colic vessels. The SMA and SMV were then stripped of investing adventitia, and the mesentery to jejunum and colon were transected radially. Jejunum and colon were not transected and reanastomosed. To confirm extrinsic denervation 1, 3, and 6 months later, segments of small bowel were stained for protein gene product 9.5 (PGP9.5) and tyrosine hydroxylase (TH). Tyrosine hydroxylase immunoreactive intensity was then quantified using a semiquantitative analysis. Immunohistochemical fluorescence showed persistence of PGP9.5 immunoreactivity confirming enteric nerves in jejunoileum; however, there was no TH immunoreactivity in jejunoileum in denervated mice despite the expected preservation of TH immunoreactivity in the still-innervated duodenum at 1 month. At 3 months, sparse immunoreactivity for TH was present, and by 6 months, reinnervation of TH-containing nerves appeared similar to controls. Quantification of intensity at each time-point further confirmed this trend. This technique in the mouse accomplishes a complete extrinsic denervation of jejunoileum early postoperatively (1 and 3 months); reinnervation occurs by 6 months. This is an easily learned murine model of orthotopic SBT. Presented at the American Gastroenterological Association during Digestive Disease Week in Los Angeles, CA, as a poster presentation on May 23 2006. Abstract published in GastroenterologyE 2006; 130:A604.  相似文献   
13.
BACKGROUND: Although it is clear that dissemination via the blood system involves angiogenesis, it is uncertain whether tumors also induce lymphangiogenesis or simply invade existing peritumoral vessels. The purpose of this study was to elucidate changes in tumor blood and lymph vessels in cases involving the invasion of squamous cell carcinoma in the oral cavity, and its significance. Blood and lymph vessels densities in tongue carcinomas induced in hamsters were investigated. METHODS: Tongue cancer was induced by abrading the right margin of the tongue of each hamster with an endodontic barbed broach and subsequently applying 1.0% 9,10-dimenthl-1,2-benzanthracene (DMBA) dissolved in acetone, three times a week, at the same site. Fresh frozen sections were prepared and blood vessels stained blue by perfusion with Coomassie Brilliant Blue and lymph vessels stained brown for 5'-nucleotidase. The effects on the blood vessels and lymph vessels were observed. RESULTS: The results showed that blood and lymph vessel densities were greater in the advanced carcinoma tissues than in normal tissue. These were compared in terms of the mode of cancer invasion. As tumor invasion progressed, the blood vessel density decreased but lymph vessel density tended to be higher in high-degree tumor invasion than in low-degree tumor invasion. The expression of vascular endothelial growth factor-C was seen more frequently as tumor invasion progressed. CONCLUSIONS: The present findings indicated that angiogenesis and lymphangiogenesis are affected by cancerous invasion.  相似文献   
14.
目的:探讨和研究治疗晚期面瘫的手术治疗,总结应用以足底内侧动静脉为蒂的(足母)展肌游离移植一期修复晚期面瘫40例效果和经验.方法:选取(足母)展肌为供肌,以足底内侧动静脉及其延续的胫后动静脉为血管蒂,以支配(足母)展肌神经及其延续的足底内侧神经和胫神经为神经蒂.(足母)展肌移植于患侧面部皮下,肌近断固定于口角,远端固定于耳前颧弓,血管神经蒂通过上唇皮下隧道与健侧面动静脉和面神经颊支吻合.结果:经随访一年以上,23例恢复了面部静态对称和理想的下面部随意和不随意运动;8例恢复了面部静态对称和部分下面部随意和不随意运动;9例仅恢复了面部静态对称.结论:(足母)展肌游离移植一期修复晚期面瘫具有疗效好、手术操作简便、肌肉大小适中、血管神经蒂走行位置恒定紧密伴行、血管神经蒂可切取较长、变跨面神经移植和肌肉移植的两期移植为一期移植等优点;而且,神经是血管化移植.  相似文献   
15.
A cDNA encoding a transmembrane 140 kDa isoform of the neural cell adhesion molecule, NCAM, was transfected into the rat glioma cell line BT4Cn. Transfectants with a homogeneously high expression of NCAM-B showed a decreased capacity for penetration of an artificial basement membrane when compared to cells transfected with expression-vector alone or untransfected cells. However, when injected subcutaneously into nude mice, both NCAM expressing cells and control cells produced invasive tumors. Nude mice injected with NCAM positive cells developed tumors with slower growth rates as compared to those induced by NCAM negative cells. This implies that NCAM may not only be involved in adhesive and motile behaviour of glioma cells, but also in their growth regulation.  相似文献   
16.
This study investigated the relationship between the development of diabetic retinopathy and pubertal status at onset of diabetes in 521 Type 1 diabetic patients diagnosed between 1950 and 1985. Pubertal status was based on age at onset (girls ≧ 11 years and boys ≧ 12 years). Retinopathy (all forms) developed in 112 patients (21.5%; 65 background and 47 proliferative retinopathy). For subjects diagnosed in either the prepubertal or postpuberal period, a similar proportion survived without developing retinopathy for any given duration of diabetes (X2 = 0.3822, p = 0.54). However, if only the postpubertal duration of diabetes is considered, then the proportion of patients surviving without retinopathy was significantly less for those diagnosed in the prepubertal period (X2 = 14.2, p = 0.002). This study suggests that the prepubertal duration of diabetes is an important phase and that the years prior to puberty do contribute to the risk of developing microvascular injury.  相似文献   
17.
微血管减压术治疗舌咽神经痛16例临床分析   总被引:4,自引:1,他引:3  
目的 研究舌咽神经痛 (glossopharyngealneuralgia,GPN)手术治疗的最佳术式 ,评估微血管减压手术(microvasculardecompression ,MVD)的效果、并发症和随访结果 ,探讨可能的治疗机制。方法  2 0 0 0年 12月到2 0 0 3年 10月间 ,16例GPN患者接受了MVD ,无一例行神经根切断术。患者全部进行了电话或信件随访。结果 15例患者术后疼痛消失 ,1例患者为不典型GPN ,术后疼痛减轻。 1例患者术后出现轻度声音嘶哑和吞咽困难 ,1例患者出现偶发干咳。本组患者平均随访时间为 14 .1± 6 .3月 ,随访期间无一例复发。结论 MVD是治疗舌咽神经痛的一种安全、有效的手术方式 ,尤其适用于典型的GPN患者。  相似文献   
18.
Invasion of the reconstituted extracellular matrix composite, Matrigel, by eight human glioma–derived cell lines and human fetal brain cells was assessed in vitro using 8 um polycarbonate filters in a modified Boyden migration chamber. With the exception of one low grade glioma derived cell line, all lines studied proved to be invasive while normal fetal brain cells failed to invade. This invasive potential was independent of the histological grade of the tumour from which the cell lines originated. In addition, the expression of the metastasis–associated gene 18A2lmts1 as well as the tissue inhibitor of metalloproteinases–2 (TIMP–2) was analysed in each of the glioma–derived cell lines. The 18A2/mtsl was expressed in all the cells studied with the exception of fetal brain cells and the low grade non–invasive glioma derived IPRK–7 cell line. The 18A2/mtsl related genes coding for the S100 subfamily of calcium binding proteins were found to be differentially and overexpressed in invasive cell lines. TIMP–2 was expressed only in noninvasive cell lines. These results suggest that the 18A2/ mtsl and TIMP–2 genes could play an important role in the invasive behaviour of human glioma cells in vitro. .  相似文献   
19.
Summary The serratus anterior muscle in the rat is supplied by the serratus division of thoracodorsal vessels, in a pattern similar to man [2]. The serratus anterior muscles were transferred to the groin area as a free muscle flap in 17 rats and as a free muscle graft in 13 rats. In the free muscle flap group, the serratus anterior muscles of 8 of 10 rats survived; histological examination showed them to be viable and the vascular anastomoses were patent at the 30th day. In the free muscle graft group, all of the muscle grafts became necrotic. As a result, it is concluded that the microvascular transfer of serratus anterior muscles in rats is a useful small animal model for microsurgical laboratory training of clinical free flap transfers and also for performing pharmacological and biochemical studies in transplanted muscle.  相似文献   
20.
Basosquamous carcinoma of the skin is a rare malignancy with specific histopathological features of both basal cell carcinoma and squamous cell carcinoma. Some authors believe that basosquamous carcinoma is a variant of basal cell carcinoma, while others suggest that this tumour may behave more aggressively. We present a 44-year-old female patient who was diagnosed with a basosquamous carcinoma histopathologically. She had extensive ulcero-vegetative lesions, involving the anterior half of the scalp, the left orbit and the left side of the face. With this case we aim to emphasize the aggressive nature of basosquamous carcinoma and review the literature.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号