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   1275612篇
  免费   94193篇
  国内免费   1984篇
耳鼻咽喉   18193篇
儿科学   42291篇
妇产科学   37816篇
基础医学   187063篇
口腔科学   35385篇
临床医学   108139篇
内科学   251539篇
皮肤病学   26502篇
神经病学   99255篇
特种医学   49987篇
外国民族医学   366篇
外科学   197612篇
综合类   26521篇
现状与发展   1篇
一般理论   304篇
预防医学   92652篇
眼科学   29074篇
药学   97794篇
  1篇
中国医学   2496篇
肿瘤学   68798篇
  2018年   11817篇
  2015年   11618篇
  2014年   16004篇
  2013年   24355篇
  2012年   33555篇
  2011年   35955篇
  2010年   21218篇
  2009年   20023篇
  2008年   34989篇
  2007年   37952篇
  2006年   38511篇
  2005年   37818篇
  2004年   36391篇
  2003年   35392篇
  2002年   34929篇
  2001年   58110篇
  2000年   59597篇
  1999年   50702篇
  1998年   14235篇
  1997年   12814篇
  1996年   13073篇
  1995年   12348篇
  1994年   11764篇
  1993年   10861篇
  1992年   41000篇
  1991年   40370篇
  1990年   39896篇
  1989年   38717篇
  1988年   36118篇
  1987年   35363篇
  1986年   33732篇
  1985年   32151篇
  1984年   23940篇
  1983年   20835篇
  1982年   12382篇
  1981年   10935篇
  1980年   10207篇
  1979年   22643篇
  1978年   15879篇
  1977年   13734篇
  1976年   12978篇
  1975年   14205篇
  1974年   16689篇
  1973年   16087篇
  1972年   15319篇
  1971年   14238篇
  1970年   13221篇
  1969年   12733篇
  1968年   11986篇
  1967年   10484篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
IntroductionPain is highly prevalent in patients with multiple sclerosis (MS); it is chronic in 50% of cases and is classified as nociceptive, neuropathic, or mixed-type. Pain affects quality of life, sleep, and the activities of daily living. Electrotherapy is an interesting alternative or complementary treatment in the management of pain in MS, with new innovations constantly appearing.Material and methodsThis study evaluates the effectiveness of treatment with monopolar dielectric transmission of pulsed electromagnetic fields (PEMF) for pain associated with MS. We performed a randomised, placebo-controlled clinical trial including 24 patients, who were assessed with the Brief Pain Inventory, the Multiple Sclerosis International Quality of Life questionnaire, the Beck Depression Inventory, and the Modified Fatigue Impact Scale.ResultsStatistically significant improvements were observed in maximum and mean pain scores, as well as in the impact of pain on work, personal relationships, and sleep and rest. Not significant differences were found between the treatment and placebo groups.ConclusionsTreatment with PEMF may be effective in reducing pain in patients with MS, although further research is necessary to confirm its effectiveness over placebo and to differentiate which type of pain may be more susceptible to this treatment.  相似文献   
102.
Capillary malformation–arteriovenous malformation syndrome (CM‐AVM) is an autosomal dominant disorder caused by RASA1 mutations. The prevalence and phenotypic spectrum are unknown. Evaluation of patients with multiple CMs is challenging because associated AVMs can be life threatening. The objective of this study was to describe the clinical characteristics of children presenting with features of CM‐AVM to an academic pediatric dermatology practice. After institutional review board approval was received, a retrospective chart review was performed of patients presenting between 2009 and 2012 with features of CM‐AVM. We report nine cases. Presenting symptoms ranged from extensive vascular stains and cardiac failure to CMs noted incidentally during routine skin examination. All demonstrated multiple CMs, two had Parkes Weber syndrome, and two had multiple infantile hemangiomas. Seven patients had family histories of multiple CMs; three had family histories of large, atypical CMs. Six had personal or family histories of AVMs. Genetic evaluation was recommended for all and was pursued by six families; four RASA1 mutations were identified, including one de novo. Consultations with neurology, cardiology, and orthopedics were recommended. Most patients (89%) have not required treatment to date. CM‐AVM is an underrecognized condition with a wide clinical spectrum that often presents in childhood. Further evaluation may be indicated in patients with multiple CMs. This study is limited by its small and retrospective nature.  相似文献   
103.
104.
105.
In this review we summarize the impact of the various modalities of breast cancer therapy coupled with intrinsic patient factors on incidence of subsequent treatment-induced myelodysplasia and acute myelogenous leukemia (t-MDS/AML). It is clear that risk is increased for patients treated with radiation and chemotherapy at younger ages. Radiation is associated with modest risk, whereas chemotherapy, particularly the combination of an alkylating agent and an anthracycline, carries higher risk and radiation and chemotherapy combined increase the risk markedly. Recently, treatment with granulocyte colony-stimulating factor (G-CSF), but not pegylated G-CSF, has been identified as a factor associated with increased t-MDS/AML risk. Two newly identified associations may link homologous DNA repair gene deficiency and poly (ADP-ribose) polymerase inhibitor treatment to increased t-MDS/AML risk. When predisposing factors, such as young age, are combined with an increasing number of potentially leukemogenic treatments that may not confer large risk singly, the risk of t-MDS/AML appears to increase. Patient and treatment factors combine to form a biological cascade that can trigger a myelodysplastic event. Patients with breast cancer are often exposed to many of these risk factors in the course of their treatment, and triple-negative patients, who are often younger and/or BRCA positive, are often exposed to all of them. It is important going forward to identify effective therapies without these adverse associated effects and choose existing therapies that minimize the risk of t-MDS/AML without sacrificing therapeutic gain.

Implications for Practice

Breast cancer is far more curable than in the past but requires multimodality treatment. Great care must be taken to use the least leukemogenic treatment programs that do not sacrifice efficacy. Elimination of radiation and anthracycline/alkylating agent regimens will be helpful where possible, particularly in younger patients and possibly those with homologous repair deficiency (HRD). Use of colony-stimulating factors should be limited to those who truly require them for safe chemotherapy administration. Further study of a possible leukemogenic association with HRD and the various forms of colony-stimulating factors is badly needed.
  相似文献   
106.
107.
108.
109.
Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM‐202 and 203) and two precipitated (NM‐200 and ‐201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)‐modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose‐dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells. Environ. Mol. Mutagen. 56:218–227, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
110.
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