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   160475篇
  免费   31636篇
  国内免费   2451篇
耳鼻咽喉   5228篇
儿科学   5583篇
妇产科学   2508篇
基础医学   4377篇
口腔科学   1653篇
临床医学   27270篇
内科学   49720篇
皮肤病学   7541篇
神经病学   15542篇
特种医学   6725篇
外科学   42872篇
综合类   251篇
现状与发展   72篇
预防医学   7222篇
眼科学   3542篇
药学   1826篇
中国医学   71篇
肿瘤学   12559篇
  2024年   690篇
  2023年   4824篇
  2022年   1266篇
  2021年   3211篇
  2020年   6106篇
  2019年   2269篇
  2018年   7536篇
  2017年   7430篇
  2016年   8516篇
  2015年   8542篇
  2014年   15650篇
  2013年   15803篇
  2012年   5771篇
  2011年   5830篇
  2010年   10523篇
  2009年   14366篇
  2008年   6122篇
  2007年   4382篇
  2006年   6860篇
  2005年   4170篇
  2004年   3419篇
  2003年   2369篇
  2002年   2544篇
  2001年   4105篇
  2000年   3379篇
  1999年   3568篇
  1998年   3776篇
  1997年   3551篇
  1996年   3479篇
  1995年   3294篇
  1994年   2043篇
  1993年   1653篇
  1992年   1709篇
  1991年   1722篇
  1990年   1331篇
  1989年   1493篇
  1988年   1290篇
  1987年   1106篇
  1986年   1129篇
  1985年   949篇
  1984年   694篇
  1983年   642篇
  1982年   573篇
  1981年   440篇
  1980年   400篇
  1979年   431篇
  1978年   421篇
  1977年   452篇
  1975年   342篇
  1972年   353篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Cerebrospinal fluid (CSF) from 7 patients with infantile spasms (mean age: 6.7 months) was collected before and after treatment with adrenocorticotropic hormone (ACTH). The concentration of neurotransmitter metabolites was analyzed using high-performance liquid chromatography and compared to the metabolite concentration in the CSF from 7 age-matched controls (mean age: 6.1 months). Pretreatment levels of CSF 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid, 3-methoxy-4-hydroxyphenyl glycol (MHPG), and kynurenine were significantly lower in infantile spasm patients compared to controls. Following treatment, marked increases in 5-HIAA and decreases in kynurenine levels were observed in the CSF of the 5 infants whose seizures were eliminated or reduced by ACTH. In the 2 nonresponders 5-HIAA levels decreased. The level of MHPG was reduced slightly in 5 infants, including the 2 nonresponders, and was increased in 2 responders. CSF homovanillic acid levels increased in 4 infantile spasm infants and decreased in 3 following ACTH. These data demonstrate that the presence of seizures in infantile spasms is associated with a significant decrease in serotonergic activity and that elimination of seizures by ACTH is accompanied by increased serotonin turnover. The simultaneous increase of 5-HIAA and decrease of kynurenine, an alternate metabolite of tryptophan, suggests an underlying disturbance of tryptophan metabolism in infantile spasms. The possibility that elimination of seizures by ACTH may be related to decreased production of certain kynurenine metabolites, particularly quinolinic acid, is discussed.  相似文献   
103.
Myelofibrosis with myeloid metaplasia (MMM) is currently classified as a classic (ie, BCR-ABL-negative) myeloproliferative disorder characterized by anemia, multiorgan extramedullary hematopoiesis, constitutional symptoms, and premature death from either leukemic transformation or other disease complications. Stem cell transplantation can be curative, but many patients either are not appropriate candidates or do not choose to accept the significant risks associated with transplantation. Current pharmacologic therapy has been beneficial mainly in terms of palliating disease-associated cytopenias, constitutional symptoms, splenomegaly, and other organ damage from excess myeloproliferation. Novel treatment strategies are under investigation, including targeted inhibition of JAK2V617F, the activating tyrosine kinase point mutation present in about half of patients with MMM. In this article, we review both the old and new pharmacologic options for MMM.  相似文献   
104.
105.
106.
107.
108.
Clinical outcomes data can be used to facilitate patient management decisions, assess clinician and organizational performance, and to provide evidence for the effectiveness of surgery and rehabilitation. The validity of the inferences made from outcomes data are dependent on the validity of the outcomes measures themselves and the circumstances under which the data were collected, analyzed, and interpreted. Clinical outcomes may include measures of impairment of body structure and function, activity limitation, and participation restriction. However, because the relationship between impairment and the resulting activity limitation and participation restriction is not direct, and because activity limitations and participation restrictions are of the utmost concern to the athlete, the primary clinical outcome should be measures of activity limitation and participation restriction. Activity limitation and participation restriction may be measured either through direct observation of performance or by general or specific measures of health related quality of life. Clinical outcomes data must be collected systematically to ensure valid inferences from the data.  相似文献   
109.
Background. Modern medicine is rooted in ethnobotanical traditions using indigenous flora to treat symptoms of human diseases or to improve specific aspects of the body condition. Herbal medicine is now used by over half of the American population. Yet the American medical community generally lacks knowledge of the function, metabolism, interaction, adverse reactions, and preparation of herbal products.
Objective. Because over 60 botanicals are marketed in cosmeceutical formulations, dermatologists need to obtain working knowledge of the major botanicals. The preparation, traditional uses, mechanisms of action, human clinical data, adverse reactions, and interactions all impact herbal efficacy and are discussed below.
Method. English-language medical journal and symposium searches.
Results. The most important botanicals pertaining to dermatologic uses, such as cosmeceuticals, include teas, soy, pomegranate, date, grape seed, Pycnogenol, horse chestnut, German chamomile, curcumin, comfrey, allantoin, and aloe. All are documented to treat dermatologic conditions. Only green and black tea, soy, pomegranate, and date have published clinical trials for the treatment of parameters of extrinsic aging.
Conclusions. Preparation of botanical-based cosmeceuticals is complex. Very few of these products are supported by evidence-based science.
CARL THORNFELDT, MD, FAAD, HAS INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS.  相似文献   
110.
BACKGROUND: Solid organ transplant recipients may develop numerous or life-threatening skin cancers. In addition to aggressive standard treatment of skin cancer, reduction of immunosuppression has been considered an adjuvant therapeutic strategy, albeit without direct proof of efficacy. OBJECTIVE: To review the rationale for and evidence supporting the efficacy of reduction of immunosuppression for severe skin cancer in transplant recipients. METHODS: Review of the literature regarding direct and indirect evidence on reduction of immunosuppression for transplant-associated skin cancer. RESULTS: Although there are no randomized controlled trials of reduction of immunosuppression as a therapeutic intervention for transplant patients with skin cancer, multiple lines of evidence suggest that this strategy may be an effective adjuvant therapy. A randomized trial has demonstrated a lower incidence of skin cancer in transplant recipients after reduction of immunosuppression, albeit in a cohort not previously affected by skin cancer. Case series of reduction or cessation of immunosuppression demonstrate a lower incidence of skin cancer or improved outcomes of preexisting skin cancer. Lower overall immunosuppression is associated with a lower incidence of skin cancer. Multiple cancers affecting the skin have been shown to regress with reduction of immunosuppression. CONCLUSIONS: Reduction of immunosuppression may be an effective adjuvant therapeutic strategy when confronting severe transplant-associated skin cancer. The risks of reduction of immunosuppression must be better defined, and randomized trials of this strategy are necessary.  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