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   33257篇
  免费   3040篇
  国内免费   590篇
耳鼻咽喉   509篇
儿科学   1309篇
妇产科学   501篇
基础医学   2847篇
口腔科学   1220篇
临床医学   3471篇
内科学   5121篇
皮肤病学   460篇
神经病学   10318篇
特种医学   449篇
外科学   1465篇
综合类   2290篇
现状与发展   3篇
一般理论   1篇
预防医学   3523篇
眼科学   217篇
药学   2292篇
  13篇
中国医学   491篇
肿瘤学   387篇
  2024年   88篇
  2023年   806篇
  2022年   805篇
  2021年   1729篇
  2020年   1684篇
  2019年   1631篇
  2018年   1554篇
  2017年   1568篇
  2016年   1471篇
  2015年   1362篇
  2014年   2114篇
  2013年   3206篇
  2012年   1727篇
  2011年   2016篇
  2010年   1518篇
  2009年   1586篇
  2008年   1615篇
  2007年   1469篇
  2006年   1300篇
  2005年   997篇
  2004年   856篇
  2003年   861篇
  2002年   692篇
  2001年   503篇
  2000年   423篇
  1999年   374篇
  1998年   368篇
  1997年   311篇
  1996年   251篇
  1995年   245篇
  1994年   202篇
  1993年   182篇
  1992年   196篇
  1991年   139篇
  1990年   146篇
  1989年   93篇
  1988年   104篇
  1987年   98篇
  1986年   85篇
  1985年   105篇
  1984年   78篇
  1983年   58篇
  1982年   49篇
  1981年   45篇
  1980年   33篇
  1979年   36篇
  1978年   33篇
  1977年   26篇
  1976年   15篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Baicalin is a natural bioactive compound derived from Scutellaria baicalensis, which is extensively used in traditional Chinese medicine. A literature survey demonstrated the broad spectrum of health benefits of baicalin such as antioxidant, anticancer, anti-inflammatory, antimicrobial, cardio-protective, hepatoprotective, renal protective, and neuroprotective properties. Baicalin is hydrolyzed to its metabolite baicalein by the action of gut microbiota, which is further reconverted to baicalin via phase 2 metabolism in the liver. Many studies have suggested that baicalin exhibits therapeutic potential against several types of hepatic disorders including hepatic fibrosis, xenobiotic-induced liver injury, fatty liver disease, viral hepatitis, cholestasis, ulcerative colitis, hepatocellular and colorectal cancer. During in vitro and in vivo examinations, it has been observed that baicalin showed a protective role against liver and gut-associated abnormalities by modifying several signaling pathways such as nuclear factor-kappa B, transforming growth factor beta 1/SMAD3, sirtuin 1, p38/mitogen-activated protein kinase/Janus kinase, and calcium/calmodulin-dependent protein kinase kinaseβ/adenosine monophosphate-activated protein kinase/acetyl-coenzyme A carboxylase pathways. Furthermore, baicalin also regulates the expression of fibrotic genes such as smooth muscle actin, connective tissue growth factor, β-catenin, and inflammatory cytokines such as interferon gamma, interleukin-6 (IL-6), tumor necrosis factor-alpha, and IL-1β, and attenuates the production of apoptotic proteins such as caspase-3, caspase-9 and B-cell lymphoma 2. However, due to its low solubility and poor bioavailability, widespread therapeutic applications of baicalin still remain a challenge. This review summarized the hepatic and gastrointestinal protective attributes of baicalin with an emphasis on the molecular mechanisms that regulate the interaction of baicalin with the gut microbiota.  相似文献   
992.
目的 观察增龄对大鼠运动功能、纹状体多巴胺转运体(DAT)功能和蛋白表达的影响.方法 旋转棒潜伏期测定各增龄组大鼠运动功能;131 I-FP-β-CIT(N-(3'-氟丙基)-2β羰甲氧基-3β(4'-碘苯基)托烷摄取率测定纹状体DAT结合活性;Western-blot检测DAT蛋白表达水平.结果 大鼠旋转棒潜伏期和纹状体131 I-FP-β-CIT摄取率在6月龄后均呈随龄性降低,12、16月龄和20月龄与6月龄组比较差异有统计学意义(P<0.001),且二者有相关性(r=0.656,P<0.01);纹状体DAT蛋白表达水平未见随龄性改变.结论 大鼠运动功能的随龄性衰退与纹状体DAT131 I-FP-β-CIT结合活性下降有关;老龄大鼠纹状体DAT可能存在突触膜表达减少.  相似文献   
993.
994.
Spontaneous megakaryocytic colonies (CFU-MK) formation without the addition of Meg-CSA in myeloproliferative disorders (MPD) has been reported by many laboratories. The mechanism by which this occurs is still unknown. In our previous work we have found that the spontaneous colonies persisted in serum-free agar culture although the colony cells were smaller and the colony numbers fewer than in plasma clot culture and that monoclonal antibodies against IL3, IL6 and GM-CSF had no inhibitory effect on spontaneous CFU-MK in both semi-solid cultures. Recently, proto-oncogene c-mpl and c-mpl ligand, thrombopoietin (TPO), have been shown to specifically participate in the regulation of normal human megakaryocytopoiesis. In order to test the hypothesis that c-mpl c-mpl ligand pathway is involved in the spontaneous growth of megakaryocyte progenitors, we investigated mRNA expressions of c-mpl and TPO in cells grown in serum-free liquid culture using RT-PCR. The c-mpl expression was detected in the cultured cells from all nine patients (six with ET, two with PV, one with PMF) who had spontaneous CFU-MK in clonal assays. However, none of the patients expressed TPO mRNA in these cells. Pre-incubation of nonadherent mononuclear cells with thioester-modified antisense oligodeoxynucleotide to c-mpl at a concentration of 6μ M significantly decreased the cloning efficiency of spontaneous megakaryocyte growth by 42.5% ( P <0.05) in plasma clot assay (seven with ET, one with PV) and 69.6% ( P <0.05) in serum-free agar culture (six with ET, one with PV). In control experiments the introduction of a scrambled oligomer to antisense oligodeoxynucleotide had no such effect on spontaneous colony formation. These results indicate that c-mpl exerts an important effect in the growth of spontaneous megakaryocytopoiesis in MPD.  相似文献   
995.
This study describes five patients with slowly developing dysphagia secondary to oculopharyngeal muscular dystrophy (OPMD), a progressive neurological disorder characterized by gradual onset of dysphagia, ptosis, and facial and trunk limb weakness. OPMD is a genetic disorder that affects formerly healthy adults who typically begin to experience symptoms in the fourth or fifth decade of life. Despite the debilitating nature of the disease, it is common for affected individuals to live to old age. Because of the gradual progression of dysphagia, as well as the deterioration of articulation, resonance, and breath support, patients with OPMD may come to the attention of physicians, nurses, and speech pathologists before a diagnosis is made. We hope to heighten awareness of how these subjects developed strategies to cope with their swallowing problems without medical intevention until the disease was producing marked symptoms. Patients with suspected dysphagia should be questioned about overt problems with eating and swallowing, but also about their adaptations and compensatory strategies. A Clinical Interview Questionnaire is included that may yield additional information about hidden dysphagia.  相似文献   
996.
997.
998.
‘Neurodevelopmental disorders’ comprise a group of congenital or acquired long-term conditions that are attributed to disturbance of the brain and or neuromuscular system and create functional limitations, including autism spectrum disorder, attention deficit/ hyperactivity disorder, tic disorder/ Tourette’s syndrome, developmental language disorders and intellectual disability. Cerebral palsy and epilepsy are often associated with these conditions within the broader framework of paediatric neurodisability. Co-occurrence with each other and with other mental health disorders including anxiety and mood disorders and behavioural disturbance is often the norm. Together these are referred to as neurodevelopmental, emotional, behavioural, and intellectual disorders (NDEBIDs) in this paper. Varying prevalence rates for NDEBID have been reported in developed countries, up to 15%, based on varying methodologies and definitions. NDEBIDs are commonly managed by either child health paediatricians or child/ adolescent mental health (CAMH) professionals, working within multidisciplinary teams alongside social care, education, allied healthcare practitioners and voluntary sector. Fragmented services are common problems for children and young people with multi-morbidity, and often complicated by sub-threshold diagnoses. Despite repeated reviews, limited consensus among clinicians about classification of the various NDEBIDs may hamper service improvement based upon research. The recently developed “Mental, Behavioural and Neurodevelopmental disorder” chapter of the International Classification of Diseases-11 offers a way forward. In this narrative review we search the extant literature and discussed a brief overview of the aetiology and prevalence of NDEBID, enumerate common problems associated with current classification systems and provide recommendations for a more integrated approach to the nosology and clinical care of these related conditions.  相似文献   
999.
1000.
BackgroundTreadmills provide a safe and convenient way to study the gait of people with Parkinson’s disease (PD), but outcome measures derived from treadmill gait may differ from overground walking.ObjectiveTo investigate how the relationships between gait metrics and walking speed vary between overground and treadmill walking in people with PD and healthy controls.MethodsWe compared 29 healthy controls to 27 people with PD in the OFF-medication state. Subjects first walked overground on an instrumented gait walkway, then on an instrumented treadmill at 85%, 100% and 115% of their overground walking speed. Average stride length and cadence were computed for each subject in both overground and treadmill walking.ResultsStride length and cadence both differed between overground and treadmill walking. Regressions of stride length and cadence on gait speed showed a log-log relationship for both overground and treadmill gait in both PD and control groups. The difference between the PD and control groups during overground gait was maintained for treadmill gait, not only when treadmill speed matched overground speed, but also with ± 15% variation in treadmill speed from that value.SignificanceThese results show that the impact of PD on stride length and cadence and their relationship to gait speed is preserved in treadmill as compared to overground walking. We conclude that a treadmill protocol is suitable for laboratory use in studies of PD gait therapeutics.  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