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   6360篇
  免费   243篇
  国内免费   52篇
耳鼻咽喉   232篇
儿科学   353篇
妇产科学   263篇
基础医学   432篇
口腔科学   340篇
临床医学   626篇
内科学   1492篇
皮肤病学   89篇
神经病学   363篇
特种医学   243篇
外科学   1253篇
综合类   102篇
一般理论   1篇
预防医学   161篇
眼科学   241篇
药学   238篇
中国医学   10篇
肿瘤学   216篇
  2024年   5篇
  2023年   55篇
  2022年   75篇
  2021年   128篇
  2020年   104篇
  2019年   147篇
  2018年   155篇
  2017年   148篇
  2016年   178篇
  2015年   215篇
  2014年   239篇
  2013年   321篇
  2012年   445篇
  2011年   429篇
  2010年   259篇
  2009年   230篇
  2008年   515篇
  2007年   555篇
  2006年   528篇
  2005年   473篇
  2004年   377篇
  2003年   318篇
  2002年   253篇
  2001年   121篇
  2000年   112篇
  1999年   104篇
  1998年   33篇
  1997年   27篇
  1996年   22篇
  1995年   10篇
  1994年   8篇
  1993年   11篇
  1992年   12篇
  1991年   17篇
  1990年   8篇
  1988年   3篇
  1987年   3篇
  1984年   1篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
  1971年   3篇
  1970年   2篇
  1969年   1篇
排序方式: 共有6655条查询结果,搜索用时 265 毫秒
71.
72.
73.
We studied the effects of treatment with SMe1EC, a hexahydropyridoindole antioxidant, on vascular reactivity, endothelial function, and oxidonitrosative stress level of thoracic aorta in young and old rats with or without diabetes mellitus. The rats were grouped as young control (YC 3 months old), old control (OC 15 months old), young diabetic (YD), old diabetic (OD), young control treated (YCT), old control treated (OCT), young diabetic treated (YDT), and old diabetic treated (ODT). Diabetes was induced by streptozotocin injection and subsequently SMe1EC2 (10 mg/kg/day, p.o.) was administered to YCT, OCT, YDT, and ODT rats for 5 months. In young and old rats, diabetes resulted in hypertension, weight loss, hyperglycemia, and hypertriglyceridemia, which were partially prevented by SMe1EC2. SMe1EC2 also inhibited the diabetes-induced increase in aorta levels of AGEs (advanced glycosylation end-protein adducts), 4-HNE (4-hydroxy-nonenal-histidine), 3-NT (3-nitrotyrosine), and RAGEs (receptors for AGEs). The contractions of the aorta rings to phenylephrine (Phe) and KCL did not significantly change, but acetylcholine (ACh) and salbutamol relaxations were reduced in OC compared to YC rats. Diabetes induction increased Phe contractions in YC and OC rats, KCL contractions in YC rats, and did not cause further inhibition in already inhibited ACh and salbutamol relaxations in OC rats. We have achieved the lowest levels of ACh relaxation in YD rats compared to other groups. SMe1EC2 did not change the response of aorta to ACh, salbutamol and Phe in YC rats, and ameliorated ACh relaxations in OC and YD but not in OD rats. In YDT and ODT rats, increased Phe and KCL contractions, high blood pressure, and impaired salbutamol relaxations were amended by SMe1EC2. Phe contractions observed in YD and OD rats as well as KCl contractions observed in OC rats were the lowest levels when the rats were treated with SMe1EC2. When the bath solution was shifted to cyclopiazonic acid (CYP) or CYP plus Ca2+-free medium, the contraction induced by a single dose of Phe (3?×?10?6 M) was more inhibited in YD and OD than in YC but not in OC rats. In SMe1EC2-treated rats, neither the presence of CFM nor CFM plus CYP exhibited a significant change in response of aorta to a single dose of Phe. These findings suggest that α1-adrenergic receptor signaling is activated in both age groups of diabetic rats, diabetes activates K+-depolarization and calcium mobilization via CaV especially in the aorta of young rats, and sensitizes the aorta of old rats to the regulating effect of SMe1EC2. ACh relaxations were inhibited in YC rats, increased in OC rats and unchanged in YD and OD rats when aortic rings pretreated with TEA, an inhibitor of calcium-activated K+ channels (KCa), or 4-aminopyridine (4-AP), an inhibitor of voltage-sensitive K+ channels (KV). ACh relaxations were inhibited in YCT, OCT, and YDT rats in the presence of 4-AP or TEA. In ODT rats, 4-AP did not change ACh relaxation but TEA inhibited. These findings suggest that the contribution of Kv and KCa to ACh relaxation is likely upregulated by SMe1EC2 when the relaxations were inhibited by aging or diabetes. We conclude that SMe1EC2 might be a promising agent for aging and diabetes related vascular disorders.  相似文献   
74.
75.
76.
77.
AIM: To evaluate endometrioma located at cesarean scatrix.METHODS: Medical data of 6 patients who presented to our institution with abdominal wall endometrioma were evaluated retrospectively and reviewed literature in this case series. The diagnostic approaches and treatment is discussed.RESULTS: All patients had a painful mass located at abdominal scars with history of cesarean section. The ages ranged from 31 to 34 and Doppler ultrasonography (US) detected hypoechoic mass with a mean diameter of 30 mm. Initial diagnosis was endometrioma in 4 and incisional hernia in 2 of 6 patients. Treatment was achieved with surgical excision in 5 patients, and one is followed by hormone suppression therapy with gonadotropin.CONCLUSION: Malignant or benign tumors of abdominal wall and incisional hernias should be kept in mind for diagnosis of endometrioma. Imaging methods like doppler US, computed tomography and magnetic resonance imaging should be used for differential diagnosis. Definitive diagnosis can only be made histopathologically. The treatment should be complete surgical excision and take care against intraoperative auto-inoculation of endometrial tissue in order to prevent recurrences.  相似文献   
78.
Dr. U. Yilmaz 《Der Radiologe》2012,52(12):1095-1100
Intracranial arterial stenoses clinically present as acute, fluctuating or recurrent neurological deficits which are caused by hemodynamically impaired perfusion of the corresponding area of the brain. The type and the extent of the deficit, however, are not only determined by the location of the stenosis but also depend on the individual anatomical conditions of the patient, such as the degree of collateralization and variants of the circle of Willis.  相似文献   
79.
Alagille syndrome is associated with various ocular abnormalities, including pseudopapilledema or optic disk edema due to increased intracranial pressure. Several mechanisms have been proposed to explain the mechanism of intracranial hypertension in Alagille syndrome. Craniosynostosis is an unusual but significant cause of increased intracranial hypertension in Alagille syndrome. It has recently been demonstrated in animal models that Jagged1 gene in which mutations are responsible for Alagille syndrome may also take part in cranial suture formation. We report a child with Alagille syndrome and craniosynostosis who presented with pruritus, elevated liver enzymes, and suspected increased intracranial pressure.  相似文献   
80.
Aim: In diabetes mellitus (DM) patients, left ventricular dysfunction is widely evaluated and established by conventional diagnostic methods, whereas right ventricular (RV) function is not as sufficiently evaluated. The aim of this study is to assess the preclinical effects of DM on RV function by using novel Tissue Doppler Imaging (TDI)‐derived indices. Methods: The study included 96 patients with type II DM [60 with DM only and 36 patients with coexisting DM and hypertension (DMHT)] and 40 healthy controls. Conventional parameters and TDI‐derived systolic velocities of tricuspid annulus [isovolumic myocardial acceleration (IVA), peak myocardial velocity during isovolumic contraction (IVV), peak systolic velocity during ejection period (Sa), RV Tei index] were measured. Results: TDI‐derived RV IVA was significantly lower in both DM and DMHT patients compared to controls indicating subclinical impairment in RV systolic function in the study patients (P = 0,0001). However RV IVA was similar in DM and DMHT subgroup supporting RV systolic impairment in DM was independent from HT. In correlation analysis, RV IVA was significantly correlated with the existence of diabetic nephropathy (r =?0,38; P = 0,003), retinopathy (r =?0,35; P = 0,006), insulin resistance (r =?0,52; P = 0,0001). Conclusions: Diabetes is associated with subclinical RV systolic dysfunction, regardless of coexisting hypertension. Tissue Doppler‐derived IVA; is a novel, non‐invasive parameter which may be used in early detection of RV systolic dysfunction in patients with DM. (Echocardiography 2010;27:1211‐1218)  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