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   20451篇
  免费   2096篇
  国内免费   34篇
耳鼻咽喉   156篇
儿科学   600篇
妇产科学   540篇
基础医学   3067篇
口腔科学   357篇
临床医学   2992篇
内科学   3557篇
皮肤病学   404篇
神经病学   1888篇
特种医学   575篇
外科学   2507篇
综合类   449篇
一般理论   55篇
预防医学   2402篇
眼科学   314篇
药学   1515篇
中国医学   12篇
肿瘤学   1191篇
  2022年   160篇
  2021年   385篇
  2020年   203篇
  2019年   373篇
  2018年   416篇
  2017年   310篇
  2016年   346篇
  2015年   406篇
  2014年   557篇
  2013年   788篇
  2012年   1076篇
  2011年   1153篇
  2010年   617篇
  2009年   583篇
  2008年   941篇
  2007年   1034篇
  2006年   1038篇
  2005年   1010篇
  2004年   984篇
  2003年   887篇
  2002年   846篇
  2001年   520篇
  2000年   520篇
  1999年   464篇
  1998年   258篇
  1997年   214篇
  1996年   189篇
  1995年   171篇
  1994年   156篇
  1993年   155篇
  1992年   348篇
  1991年   371篇
  1990年   347篇
  1989年   333篇
  1988年   303篇
  1987年   287篇
  1986年   279篇
  1985年   275篇
  1984年   260篇
  1983年   207篇
  1982年   145篇
  1981年   157篇
  1980年   143篇
  1979年   213篇
  1978年   196篇
  1977年   154篇
  1976年   137篇
  1975年   128篇
  1974年   165篇
  1973年   144篇
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
51.
OBJECTIVE: Reflection enables learners to analyze their experiences and capture the wisdom that lies within. Effective teaching requires reliable methods of assessment. Several methods of assessing reflective writing have been described; however, they often require significant training, and reliability has seldom been assessed. This study was designed to determine the interrater reliability of a method of assessing reflective writing by using a modified Bloom's Taxonomy. METHODS: Twenty-one third-year medical students maintained reflective journals throughout their pediatric clerkship. A coding schema based on Bloom's Taxonomy was developed to assess the level of cognitive processing evident in the journals. Journals were independently assessed by 3 raters. Percent agreement, kappa statistics, and intraclass correlation coefficients (ICC [2,1]) were used to assess interrater reliability. RESULTS: Three hundred eight entries from 21 journals were assessed. Percent agreement ranged from 78.2% to 100%. Kappa statistic for each level ranged from 0.57 +/- 0.04 to 0.73 +/- 0.04, and for the highest level of processing evident it ranged from 0.52 +/- .04 to 0.58 +/- 0.04. ICC (2,1) for each level of cognitive processing ranged from 0.62 (F = 6.20; P = .000) to 1.00, and for the highest level of cognitive processing evident, it was 0.79 (F = 12.42; P = .000). Substantial to almost perfect agreement was attained. CONCLUSIONS: Reflective journals allow learners to revisit their experiences for critical analysis and deeper learning. This study describes a reliable method, based on Bloom's Taxonomy, of determining whether learners have achieved higher order thinking through reflective journal writing. This method can provide a baseline for facilitating higher order processing, critical thinking, and reflective practice.  相似文献   
52.
53.
54.
Osteogenesis is synergistically enhanced by the combined effect of complimentary factors. This study showed that Nell-1 and BMP-2 synergistically enhanced osteogenic differentiation of myoblasts and phosphorylated the JNK MAPK pathway. The findings are important because of the osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of coordinated BMP-2 and Nell-1 delivery. INTRODUCTION: BMPs play an important role in the migration and proliferation of mesenchymal cells and have a unique ability to alter the differentiation of mesenchymal cells toward chondrogenic and osteogenic lineages. Signaling upstream of Cbfa1/Runx2, BMPs effects are not limited to cells of the osteoblast lineage. Thus, additional osteoblast-specific factors that could synergize with BMP-2 would be advantageous for bone regeneration procedures. NELL-1 (NEL-like molecule-1; NEL [a protein strongly expressed in neural tissue encoding epidermal growth factor like domain]) is a novel growth factor believed to preferentially target cells committed to the osteochondral lineage. MATERIALS AND METHODS: C2C12 myoblasts were transduced with AdLacZ, AdNell-1, AdBMP-2, or AdNell-1+AdBMP-2 overexpression viruses. Effects were studied by cell morphology, alkaline phosphatase activity, osteopontin production, and MAPK signaling. Additionally, in a nude mouse model, viruses were injected into leg muscles, and new bone formation was examined after 2 and 8 wk. RESULTS: C2C12 myoblasts co-transduced with AdNell-1+AdBMP-2 showed a synergistic effect on osteogenic differentiation as detected by alkaline phosphatase activity and osteopontin production. Nell-1 stimulation on AdNell-1 + AdBMP-2 preconditioned C2C12 cells revealed significant activation of the non-BMP-2 associated c-Jun N-terminal kinase (JNK) MAPK signaling pathway, but not the p38 or extracellular signal-regulated kinase (ERK1/2) MAPK pathways. Importantly Nell-1 alone did not induce osteogenic differentiation of myoblasts. In a nude mouse model, injection of AdNell-1 alone stimulated no bone formation within muscle; however, injection of AdNell-1+AdBMP-2 stimulated a synergistic increase in bone formation compared with AdBMP-2 alone. CONCLUSIONS: These findings are important because of the confirmed osteochondral specificity of Nell-1 signaling and the potential therapeutic effects of enhanced BMP-2 action with coordinated Nell-1 delivery.  相似文献   
55.

Background  

Studies have found that deaf individuals have higher rates of psychiatric disorder than those who are hearing, while at the same time encountering difficulties in accessing mental health services. These factors might increase the risk of suicide. However, the burden of suicidal behaviour in deaf people is currently unknown.  相似文献   
56.
RATIONALE: A small percentage of patients with idiopathic generalized epilepsy (IGE) do not respond to medical therapy. Generalized tonic-clonic (GTC) seizures are especially debilitating and can be associated with severe injuries. The benefit, safety and effect of corpus callosotomy (CC) in patients with IGE have not been studied. METHODS: We reviewed patients with presumed IGE who underwent CC between 1991 and 2000. Criteria for selection included history, examination, brain imagining, interictal and ictal EEG. All patients had refractory and debilitating tonic-clonic seizures (GTCS) and had failed four or more antiepileptic drugs. Seizure frequency was calculated per month over the last year and pre-operative baseline was compared to last follow-up using paired t-tests. IQ, executive function, language and verbal, non-verbal memory and quality of life (QOL) was compared before and after surgery. Serial EEGs after surgery were reviewed. RESULTS: There were nine patients (seven men), mean age 37.9 (range: 22-49), mean IQ 87.3 (range: 75-107). All had anterior CC. Mean follow-up time was 5.4 years (range: 0.6-10.3 years). One patient died from sudden death in epilepsy 9 months after surgery. There was a significant reduction of GTC seizures from 6.3 to 1.1 (p<0.005). Four patients had more than 80% and eight more than 50% reduction. Of five patients with absence seizures, two became seizure free and one had more than 80% reduction and two worsened slightly, and of three with myoclonic seizures one had more than 90% reduction. One patient had completion of the CC with improvement of myoclonus and absence seizures, but not of GTC seizures and suffered a disconnection syndrome. Another had right frontal focal resection without improvement after new seizures of focal onset. Cognitive testing showed a good outcome (improved or no change) in all cognitive domains. Post-surgical EEG showed new focal slowing and sharp waves. There was no change in QOL. CONCLUSION: CC can be effective in reducing GTC, absence and myoclonic seizures in patients with refractory IGE. These findings suggest that interhemispheric communication of the cerebral cortices plays an important role in the generation of seizures in IGE. Anterior CC appears safe while complete callosotomy has a risk of disconnection syndrome.  相似文献   
57.
Over 20 years ago, the Birmingham Blood Centre established a facility for the cryopreservation of bone marrow (BM) for patients in the West Midlands suffering from haematopoietic disorders and for whom a bone marrow transplant was indicated. Today, the use of mobilised peripheral blood (PBSC) has overtaken bone marrow as the source of stem cells for transplantation and the numbers of patients benefitting and the diversity of conditions being treated has increased enormously. Allogeneic transplants, using stem cells from healthy donors, have become increasingly successful as a result of an improving understanding of the complexities of the HLA histocompatibility system. Additionally umbilical cord blood (HUC), which in the 1980s was recognised as a source of stem cells, can now be collected and used for transplantation. As scientific knowledge and the clinical management of patients has advanced, so too have laboratory methods for manipulating cell products to enrich or deplete certain cell populations (e.g. by CD34+cell selection) in order to minimise potentially fatal graft-versus-host disease (GVHD) or to eliminate tumour cells in the case of autologous patients. Donor lymphocytes (DLI) may also be collected and used to aid a graft-versus-leukaemia (GVL) effect. The laboratory is currently developing protocols for immunotherapy using virus-specific T cells which can be prepared and infused to combat potentially fatal CMV disease post-transplant. Clinical trials of vaccines employing tumour specific dendritic cells for treating patients with hepatocellular carcinoma (HCC) and metastatic melanoma (MM), which do not respond to conventional treatments, are also underway. The advances and expansion in the Stem Cell and Immunotherapy (SCI) service in Birmingham over the last 10 year period are reflected in the table below:
 
  相似文献   
58.
This study provides additional information on the psychometric properties of the Sexual Aversion Scale (SAS). Results suggest a positive relationship between sexual aversion, generalized anxiety, and history of sexual victimization. Variables such as age and religiosity were unrelated to scores on the SAS, although females reported significantly more sexual anxiety than males. The factor structure of the SAS is described and suggests that sexual aversion is a multifaceted problem with at least three and possibly four different dimensions.  相似文献   
59.
Abstract The aim of the present paper was to describe some formative projects on work integration of patients with epilepsy and mild cognitive deficits, so that similar initiatives may be promoted. The different phases of the formative projects were described: the inclusion criteria, the selection of participants, the assessment instruments, the courses themselves and the final results in terms of working experience. Thirteen participants were selected for each course. Patients were treated in different Lombardy Epilepsy departments, which addressed them to the Epilepsy Center, S. Paolo Hospital, Milan, where the selection took place. Seventy percent of the participants in the formative courses found a job in 1 year, even though most of the positions were temporary. The work integration seemed to be mainly related to the level of intelligence and to verbal memory. We stress the importance of organising similar courses in the future, in the context of wider networks. This will help more patients in acquiring both economic and psychological autonomy from their families.  相似文献   
60.
We determined how noninvasive presurgical data relate to prognosis after temporal lobectomy in patients with independent bilateral temporal lobe (IBTL) complex partial seizures on the intracranial electroencephalogram (EEG). Between 1986 and 1994, 28 patients had IBTL seizures on intracranial EEG. Fifteen of these 28 patients underwent temporal lobectomy and 13 were not offered surgery. Of the 15 patients who had surgery, 10 patients became seizure-free. Magnetic resonance imaging (MRI) and the Wada test were the only variables associated with a seizure-free outcome. Seven of 10 seizure-free patients had a lateralized Wada result or the presence of unilateral hippocampal sclerosis, whereas none of the patients with persistent seizures had either of these findings. Variables not found to be predictive of a seizure-free outcome included location of scalp interictal spikes, degree of seizure-onset laterality, presence of early epilepsy risk factor, duration of epilepsy, and full-scale intelligence quotient. We conclude that MRI and the Wada test provide information of prognostic value in patients with bilateral temporal seizures independent of intracranial EEG data.  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