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   929篇
  免费   76篇
  国内免费   30篇
耳鼻咽喉   3篇
儿科学   14篇
妇产科学   167篇
基础医学   156篇
口腔科学   20篇
临床医学   81篇
内科学   97篇
皮肤病学   3篇
神经病学   38篇
特种医学   15篇
外科学   84篇
综合类   45篇
预防医学   97篇
眼科学   2篇
药学   127篇
中国医学   7篇
肿瘤学   79篇
  2024年   1篇
  2023年   38篇
  2022年   84篇
  2021年   72篇
  2020年   82篇
  2019年   44篇
  2018年   30篇
  2017年   52篇
  2016年   81篇
  2015年   49篇
  2014年   121篇
  2013年   85篇
  2012年   60篇
  2011年   21篇
  2010年   38篇
  2009年   40篇
  2008年   8篇
  2007年   15篇
  2006年   3篇
  2005年   10篇
  2004年   5篇
  2003年   11篇
  2002年   16篇
  2001年   8篇
  2000年   1篇
  1999年   5篇
  1998年   11篇
  1997年   8篇
  1996年   10篇
  1995年   7篇
  1994年   7篇
  1993年   4篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1989年   1篇
排序方式: 共有1035条查询结果,搜索用时 558 毫秒
61.
62.
There were few studies of cumulative live birth rates (CLBRs) based on multicenter reproductive clinical data from the general Chinese population. Here we report a retrospective cohort study, including 14 311 women with 17 315 cycles, in three reproductive centers to evaluate two estimated parameters of CLBRs with multiple transfer cycles of in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) in a Chinese population. We found that CLBRs were related to female age and endometrial thickness. By the fourth transfer cycle, the conservative and optimal estimates of CLBRs were 52.95% and 77.30% in women under 30 years of age, and 18.17% and 26.51% in those 37 years of age or older, respectively. The two estimates were 44.70% and 63.15% in women with endometrial thickness more than 7 mm, and 32.05% and 46.18% in those with less than 7 mm, respectively. In addition, body mass index (BMI), duration of infertility, and infertility diagnoses may also be related to CLBRs on certain conditions. The findings from this study on CLBRs after multiple transfer cycles of IVF/ICSI treatment on different conditions in the Chinese population should be beneficial to both infertile couples and clinicians.  相似文献   
63.
We identified a de novo 44.7 Kb interstitial 12p13.33 micro-deletion that involves solely the first exon of the CACNA1C (MIM 114205), using microarray-based comparative genomic hybridization (aCGH). The associated main phenotype is characterized by expressive language impairment, tremors, fine motor-skills delay, muscular hypotonia, and joint laxity. A careful comparison between the clinical and genomic characteristics between our proband and 20 previously reported patients, led us to propose CACNA1C haploinsufficiency as the main cause of both expressive language delay and motor-skills impairment. Pathogenic variants of CACNA1C have been associated to a plethora of clinical phenotypes, such as Timothy syndrome (TS, OMIM 601005), Brugada syndrome (BRGDA3, OMIM 611875) and a variety of neuropsychiatric disorders (bipolar disorder, major depression, schizophrenia, autism spectrum disorder, psychotic manifestations). In this report we describe a 12p13.33 micro-deletion involving one coding gene only, in contrast with previous studies that mostly concluded that a multi-genes deletion in the 12p13.33 sub-telomeric region is responsible of the minimum clinical phenotype of patients with 12p13.33 monosomy. Certainly, larger deletions spanning multiple Mb in 12p13.33 are responsible for more severe phenotypes, associated to a variable degree of dysmorphic features.  相似文献   
64.
65.
A five month old infant is reported with Eating Epilepsy (feeding epilepsy/feeding related epilepsy). This is an uncommon type of reflex epilepsy in children, and should be considered if the history and investigations for gastro esophageal reflux and apparent life threatening event are negative. A clear stepwise history helps in diagnosis.  相似文献   
66.
Ethanol is commonly used in cosmetic and pharmaceutical preparations.ObjectiveThe present study aimed to assess ethanol-induced apoptosis and the possible repair by hyaluronic acid (HA) in vitro. In addition we aimed to determine the modulation of tumor necrosis factor (TNF-α) and interferon (IFN-α).Design and methodsWe treated human A431 epidermoid skin cells and mouse fibroblasts with two concentrations of ethanol for 24 h. HA obtained from umbilical cord excision was used at three concentration levels (2%, 4% and 8%) to determine its efficacy in the treatment. We measured cytotoxicity, TNF-α and IFN-α and visualized the cultures by electron microscopy.ResultsTreatment of cells with ethanol at 50 mM and 100 mM increased both the percentage of cells undergoing apoptosis, as well as the release of TNF-α into the culture medium.ConclusionsEthanol may induce apoptosis in skin cells by enhancing the effects of TNF-α. HA in the 2% and 4% concentrations reduced TNF-α and morphological inflammation both in human A431 epidermoid skin cells and in mouse fibroblasts.  相似文献   
67.
IntroductionNonsuicidal self-injury (NSSI) is a transdiagnostic behavior associated with significant psychopathology. Research has shown a positive association between sleep disturbances, (e.g., nightmares and insomnia), and suicidal behavior, however, the relation between NSSI and sleep disturbances has yet to be examined. Sleep disturbances have been found to have a causal role in problems with emotional dysfunction. Specifically, sleep disturbances inhibit the emotion processing function of sleep. Importantly, a majority of individuals engage in NSSI to regulate intense emotions, and it is possible that sleep disturbances increase propensity for NSSI by contributing to dysregulated emotions.MethodsIn two cross-sectional studies, the present research examined whether insomnia symptoms and nightmares were related to NSSI in a clinical sample (Study 1, N = 313) and in a university sample (Study 2, N = 152). Furthermore, the hypothesis that emotional dysregulation would atemporally mediate the relationship between sleep disturbances and NSSI was tested in Study 2.ResultsFindings showed that nightmares, but not insomnia symptoms, were associated with NSSI while controlling for depressive symptoms. This pattern of findings was consistent across both clinical and university samples, which underscores the robustness of the finding. Further, the relationship between nightmares and NSSI was fully mediated by emotional dysregulation.ConclusionThe present research provides initial evidence that nightmares are atemporally associated with an increased propensity for NSSI by contributing to emotional dysregulation, and provides support for the emotion regulation function of dreams.  相似文献   
68.
《Medical hypotheses》2013,80(6):819-822
Amyotrophic lateral sclerosis (ALS) is thought to be due to primary involvement of motor neurons. Pathogenic mechanisms underlying its appearance are relatively well known and include inflammation, excitotoxicity, oxidative stress, endoplasmic reticulum stress, protein damage, genetic abnormalities and type of neuronal death. Although these processes have been investigated in detail in the past two decades none of them appear to be the cause of the illness. In addition several possible environmental agents have been investigated but the results, in every case, were conflicting and therefore inconclusive. However, since the motor neurons display the features of apoptosis in this illness, the possibility remains that the motor neurons die because of a hostile environment, one that is unable to sustain their health, rather than being directly targeted themselves.The above considerations lead to an examination of astrocytes, for these cells play a key role in controlling the environment of neurons. It is known that astrocytes are exquisitely plastic, adapting their metabolism and behaviour to the needs of the neurons they contact. Each population of astrocytes is therefore unique and, were one to be adversely affected at the start of a disease process, the consequences would extend to the neurons that it normally chaperoned. The disturbed relationship might involve inappropriate production and secretion of astrocytic neurotransmitters, defective transport of glutamate and impaired trophic and metabolic support of the motor neurons.In order to explain the spread of weakness and pyramidal signs in ALS patients, which is very often from one group of muscles to a neighbouring one, it is postulated that, within the spinal cord, the brainstem and the motor cortex, the disease-causing process is also spreading—in this case, from one group of astrocytes to its neighbours. A misfolded protein, possibly a prion-like protein, would be a candidate for this type of transmission.  相似文献   
69.
70.
Embryonic stem(ES) cells are pluripotent cells that can give rise to derivatives of all three embryonic germ layers. Due to its characteristics, the patient-specific ES cells are of great potential for transplantation therapies. Several strategies can reprogramme somatic cells back to pluripotent stem cells: nuclear transfer, fusion with ES cells, treatment with cell extract and induction by specific factors. Considering the future clinical use, the differentiation from ES to neurons, cardiomyocytes and many other types of cells currently provide basic cognition and experience to regenerative medicine. This article will review two courses, the reprogramming of differentiated cells and the differentiation of ES cells to specific cell types.  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