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   10354篇
  免费   712篇
  国内免费   51篇
耳鼻咽喉   113篇
儿科学   374篇
妇产科学   193篇
基础医学   1684篇
口腔科学   506篇
临床医学   792篇
内科学   2374篇
皮肤病学   254篇
神经病学   996篇
特种医学   163篇
外科学   1195篇
综合类   43篇
一般理论   4篇
预防医学   885篇
眼科学   191篇
药学   629篇
中国医学   53篇
肿瘤学   668篇
  2024年   9篇
  2023年   82篇
  2022年   200篇
  2021年   358篇
  2020年   222篇
  2019年   323篇
  2018年   396篇
  2017年   244篇
  2016年   290篇
  2015年   291篇
  2014年   468篇
  2013年   581篇
  2012年   834篇
  2011年   912篇
  2010年   487篇
  2009年   380篇
  2008年   710篇
  2007年   684篇
  2006年   606篇
  2005年   546篇
  2004年   528篇
  2003年   493篇
  2002年   436篇
  2001年   108篇
  2000年   134篇
  1999年   122篇
  1998年   82篇
  1997年   50篇
  1996年   46篇
  1995年   39篇
  1994年   43篇
  1993年   24篇
  1992年   41篇
  1991年   46篇
  1990年   36篇
  1989年   23篇
  1988年   29篇
  1987年   24篇
  1986年   19篇
  1985年   15篇
  1984年   23篇
  1983年   9篇
  1982年   12篇
  1981年   8篇
  1975年   8篇
  1974年   8篇
  1973年   7篇
  1972年   9篇
  1971年   7篇
  1970年   7篇
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
1.
Radiodermatitis is one of the commonest side effects of radiotherapy. They are usually assessed by semi‐quantitative clinical scores, which are not validated and may be subject to inter‐observer variability. A few previous studies suggested that high‐frequency ultrasonography (HF‐USG) is useful in the assessment of the acute phase of radiation dermatitis in breast cancer patients. (a) To monitor skin changes by HF‐USG during the course of radiotherapy due to head and neck cancers, and (b) to determine whether there is any connection between skin sonograms and the skin scoring criteria. This prospective, observational study includes patients diagnosed with head and neck cancers, treated with radiotherapy or concomitant chemoradiation. The final analysis includes six patients. In every patient, the HF‐USG as well as dermatological assessment (target lesion score—TLS and CACE v. 4.0) were performed 4×: before, in the middle, day after, and 3 months after radiotherapy. There were significant differences between non‐irradiated skin thickness and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P < .0001), as well as between irradiated, unchanged skin thickness (TLS grade 0) and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P = .0002). There was no significant difference between non‐irradiated and irradiated, unchanged skin thickness (TLS grade 0; P = .9318). In four patients, we demonstrated subepidermal low echogenic band (SLEB). HF‐USG can be useful tool to noninvasive and objective assessment of skin changes during radiotherapy.  相似文献   
2.
3.
4.
5.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
6.
7.
Classical Kaposi sarcoma (KS) usually appears on lower extremities accompanied or preceded by local lymphedema. However, the development in areas of chronic lymphedema of the arms following mastectomy, mimicking a Stewart–Treves syndrome, has rarely been described. We report an 81‐year‐old woman who developed multiple, erythematous to purple tumors, located on areas of post mastectomy lymphedema. Histopathological examination evidenced several dermal nodules formed by spindle‐shaped cells that delimitated slit‐like vascular spaces with some red cell extravasation. Immunohistochemically, the human herpesvirus type 8 (HHV‐8) latent nuclear antigen‐1 was detected in the nuclei of most tumoral cells confirming the diagnosis of KS. Lymphedema could promote the development of certain tumors by altering immunocompetence. Although angiosarcoma (AS) is the most frequent neoplasia arising in the setting of chronic lymphedema, other tumors such as benign lymphangiomatous papules (BLAP) or KS can also develop in lymphedematous limbs. It is important to establish the difference between AS and KS because their prognosis and treatment are very different. Identification by immunohistochemistry of HHV‐8 is useful for the distinction between KS and AS or BLAP.  相似文献   
8.
9.
10.
The use of endogenous Protoporphyrin IX generated through the heme biosynthetic pathway after administration of 5-aminolevulinic acid (ALA) has led to many applications in photodynamic therapy (PDT). In Buenos Aires, Argentina, the Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), reported for the first time, in 1975, porphyrin synthesis from ALA in highly dividing plant tissues. Increased porphyrin synthesis in tumours as well as cell photosensitisation was reported soon after. Our group is also interested in studying the use of new synthetic lipophilic derivatives of ALA as well as ALA delivery in liposomes. We have elucidated the mechanism of ALA transport in mammalian and yeast cells. The interactions between ALA-PDT and nitric oxide were investigated in three murine adenocarcinoma cell lines. In the National University of Río Cuarto, Córdoba, a group is devoted to the synthesis of new porphyrin-derived photosensitisers to study their effects on photoinactivation of bacterial and mammalian cells death by PDT. At the Centre of Electron Microscopy of the Cordoba National University, a prototype of a 630 nm noncoherent light source was designed and constructed. Cost of the light source and scarce knowledge of the benefits of PDT by physicians limit the spread of the treatment throughout the country.  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