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   10349篇
  免费   488篇
  国内免费   77篇
耳鼻咽喉   93篇
儿科学   182篇
妇产科学   92篇
基础医学   1170篇
口腔科学   243篇
临床医学   718篇
内科学   2434篇
皮肤病学   134篇
神经病学   709篇
特种医学   397篇
外科学   2320篇
综合类   37篇
现状与发展   1篇
预防医学   198篇
眼科学   121篇
药学   789篇
中国医学   9篇
肿瘤学   1267篇
  2023年   72篇
  2022年   149篇
  2021年   224篇
  2020年   135篇
  2019年   172篇
  2018年   216篇
  2017年   181篇
  2016年   248篇
  2015年   250篇
  2014年   329篇
  2013年   392篇
  2012年   619篇
  2011年   666篇
  2010年   416篇
  2009年   367篇
  2008年   633篇
  2007年   694篇
  2006年   669篇
  2005年   672篇
  2004年   676篇
  2003年   611篇
  2002年   588篇
  2001年   135篇
  2000年   145篇
  1999年   142篇
  1998年   156篇
  1997年   120篇
  1996年   114篇
  1995年   101篇
  1994年   87篇
  1993年   71篇
  1992年   102篇
  1991年   80篇
  1990年   89篇
  1989年   69篇
  1988年   77篇
  1987年   67篇
  1986年   54篇
  1985年   65篇
  1984年   30篇
  1983年   29篇
  1982年   16篇
  1981年   19篇
  1980年   22篇
  1979年   19篇
  1978年   22篇
  1977年   10篇
  1976年   16篇
  1974年   10篇
  1967年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
BACKGROUND: In patients with chronic kidney disease (CKD), although strong associations have been observed between malnutrition and atherosclerosis, the relationship between serum albumin concentration and angiographic changes of coronary artery disease (CAD) remains poorly explored. The goal of the present study was, in patients with CKD, to clarify the relationship between the angiographic severity of CAD and serum albumin concentration reflecting either inflammation or nutrition or both. METHODS: In this study, 100 end-stage renal disease (ESRD) patients were enrolled, who commenced long-term dialysis therapy at our hospital and underwent coronary angiography within 3 months of the first haemodialysis (HD) session. Mean age was 63+/-11 years, 20% of the subjects were female and 62% had diabetes. Severity of CAD was evaluated in terms of (i) number of vessels exhibiting CAD (>or=75% stenosis) and (ii) Gensini score (GS). Clinical characteristics and laboratory findings were recorded at initiation of long-term HD therapy. We then evaluated a possible association with the presence and degree of CAD. RESULTS: Sixty-four patients exhibited signs of CAD. Forty-one among them (64%) had multivessel disease. On univariate logistic regression analysis, age, diabetes and hypoalbuminaemia were significantly associated with multivessel CAD. Univariate linear regression analysis demonstrated a positive correlation of age and diabetes with GS, and an inverse correlation of BMI and serum albumin level with GS. Stepwise regression analysis showed age and serum albumin level to be independently associated with multivessel CAD and GS. The ROC curves demonstrated best cut-off levels of age and albumin for predicting multivessel CAD to be 70 years and 3.15 g/dl, respectively. CONCLUSION: Hypoalbuminaemia at the initiation of dialysis is an important predictor of advanced CAD, particularly in male and in diabetic patients. It may reflect mainly a state of inflammation. However, malnutrition as a confounding factor cannot be entirely excluded.  相似文献   
4.
Living donor liver transplantation (LDLT) for patients with portal vein thrombosis (PVT) involves technical difficulty. The aim of this research was to analyze their preoperative diagnosis of PVT, operative procedures, and postoperative courses of patients with preoperative PVT. Thirty-nine patients of 404 adult patients (9.7%) undergoing LDLT in our hospital from 1996 June to 2004 December had PVT at their transplantation. Twenty-nine patients had intractable ascites, 21 had gastrointestinal bleeding, and 18 had encephalopathy. The thrombus was located in the portal trunk in 23, in the portal trunk and superior mesenteric vein (SMV) in 7, and developed into the SMV and the splenic vein in 8. The occlusive grade was partial in 29, and complete in 10 patients. The thrombus was removed by a simple technique, and eversion and/or incision technique, or total removal of the portal vein (PV). The PV was reconstructed with the thrombectomized native PV, with an interposed vein graft, or porto-caval hemitransposition. Advanced PVT had a significant impact on blood loss and hospital mortality. Three out of 10 patients with residual PVT required radiological and/or surgical intervention after transplantation. In conclusion, thorough planning is essential for a successful LDLT outcome for patients with preexisting PVT.  相似文献   
5.
Anthocyanins, which are responsible for a variety of bright colors (including red, blue, and purple) in fruits, vegetables, and flowers, are consumed as dietary polyphenols. Anthocyanin-containing fruits are thought to decrease coronary heart disease and are used in anti-diabetic preparations. Diabetes is associated with a variety of cardiovascular complications that may be mediated by endothelial dysfunction, and so this study was designed mainly to characterize the influence of a synthesized anthocyanidin derivative (HK-008) over acetylcholine (ACh)-induced relaxation in mesenteric arterial beds isolated from rats. In a glucose-tolerance test in intact rats, HK-008 (30 mg/kg) reduced the glucose level as effectively as the same dose of glibenclamide. The aortic relaxation induced by pinacidil (an ATP-sensitive potassium channel opener) was greatly inhibited by glibenclamide (10 microM), and also significantly inhibited by HK-008 (10 microM). Interestingly, the ACh-induced relaxation in the perfused, preconstricted mesenteric arterial bed was significantly enhanced by HK-008 (10 microM), and this enhancement was significantly attenuated by indomethacin (10 microM). The ACh-induced mesenteric relaxation was impaired by an increase in oxidative stress, viz. superoxide-generating treatment [xanthine oxidase (XO; 0.1 U/ml) plus hypoxanthine (HX; 10 microM)]. However, this impairment was strongly suppressed by HK-008 (10 microM). These results suggest that HK-008 increases endothelium-induced relaxation by suppressing oxidative stress or modulating prostanoids signaling. This compound may therefore be useful against certain cardiovascular disorders.  相似文献   
6.
One of the pyrimidine compounds, 2-piperadino-6-methyl-5-oxo-5,6-dihydro(7H)pyrrolo[3,4-d]pyrimidine (MS-818), has neurotropic effects in vitro. Therefore, we studied the effect of MS-818 on the regeneration of the peroneal nerve in C57BL/6J mice after a crush injury. Two test groups, which received a daily intraperitoneal injection of 5 mg/kg or 10 mg/kg MS-818, respectively, were compared with controls, which received daily intraperitoneal injections of physiological saline, over a 14-day period. The maximum foot-width ratio (crushed side/uncrushed side) was obtained on days 1, 8 and 14 after the crush injury, and the various morphometric parameters were evaluated at both 5 and 10 mm distal to the proximal portion of the crush site. The significant effects of MS-818 included a larger maximum foot width (P<0.04) and a greater number of unmyelinated axons per nerve at both levels (P<0.003) in both test groups than in controls. MS-818 had no significant effects on body weight, the increase of total transverse fascicular area after the crush injury, the total number of myelinated fibers with their size distributions, or the number of nuclei of Schwann cells and macrophages. Therefore, we conclude that MS-818 promotes axonal sprouting and elongation after a crush injury in mice.  相似文献   
7.
OBJECTIVES: Bronchiolitis obliterans (BO) is the main cause of late mortality among long-term survivors of lung transplantation. Chemokine-chemokine receptor (CCR) interaction and subsequent recruitment of infiltrating cells to the graft are early events in the development of chronic rejection of transplanted lungs. The present study investigated whether blockade of chemokine receptors CCR1 and CCR5 with Met-regulated-on-activation, normal T cells expressed and secreted (RANTES), an amino-terminal modified derivative of RANTES/CCL5, affects the development of BO in murine model and we sought to determine the expression of RANTES/CCL5 and their relationship with extracellular signal-regulated kinase (ERK). Materials and Methods: BALB/c mouse tracheas were heterotopically transplanted into C57Black6 recipients and treated for 21 days with either Met-RANTES at 20 microg/day or vehicle. Animals were killed at 21 days after transplantation for histologic examination of ERK expression. RESULTS: RANTES/CCL5 was highly expressed in allografts compare to isografts. Met-RANTES treatment ameliorated fibrous airway obliteration in a mouse model of BO and decreased ERK expression. CONCLUSION: Blockade of chemokine receptors by Met-RANTES ameliorated airway obliteration and decreased ERK expression. These findings suggest that chemokine receptors CCR1 and CCR5 play significant roles in the development of chronic rejection and ERK may be a new molecular target for chronic rejection.  相似文献   
8.
Ten newer antiepileptic drugs have been developed since 1990s. These drugs have wider therapeutic spectra, fewer side-effects, and lesser drug-to-drug interactions compared with the older typical antiepileptic drugs. Among them, zonisamide was developed in Japan and has been used from 1989. Gabapentin was at length approved in 2006. The other newer antiepileptic drugs are not approved yet in Japan. Felbamate can not be used in Europe because it may induce lethal hepatic toxicity and aplastic anemia. Vigabatrin is not approved in USA because it may induce permanent visual field deficit. The USA guideline for epilepsy treatment recommends that patients with newly diagnosed epilepsy can be treated with gabapentin, lamotrigine, topiramate, and oxcarbazepine. In contrast, based on epilepsy treatment guideline in England, newer antiepileptic drugs are considered only when patients with newly diagnosed epilepsy are unable to use the older antiepileptic drugs for some reasons. All newer antiepileptic drugs are used for intractable partial epilepsies, and lamotrigine and topiramate can also be used for idiopathic generalized epilepsies. The response rate (seizure reduction rate with 50% or more) and drop-out rate are overlapping among all newer antiepileptic drugs. Gabapentin, levetiracetam, and pregabalin are eliminated from kidney, and they had no drug-to-drug interactions and can be titrated rapidly. The serum concentration of lamotrigine is decreased with co-administration of hepatic enzyme inducing drugs and is increased with co-administration of valproic acid. Hypersensitivity reactions are rare with gavapentin, levetiracetam, topiramate, and tiagabin. Psychoses are reported to be induced with zonisamide, however, they can be induced with the other newer drugs (topiramate, levetiracetam, etc.). Drug-induced psychiatric symptoms, especially depression, may be often underdiagnosed. Many of these newer drugs (gabapentine, lamotrigine, levetiracetam, oxycarbazepine, etc.) have effects on chronic neuropathic pain. Some newer drugs show mood stabilizing effects (lamotrigine, oxycarbazepine, etc.), or antianxiety effect (gabapentin, topiramate, levetiracetam, pregavalin, etc.). Wide range of action to central nervous system of these newer antiepileptic drugs may serve not only for clinical seizure suppression, but also for neuroprotection.  相似文献   
9.
10.
BACKGROUND: The objective of this study was to evaluate the clinical outcome after surgical management of renal cell carcinoma (RCC) extending to the inferior vena cava (IVC). METHODS: This study included a total of 55 patients (41 men and 14 women; mean age, 59.3 years) with RCC (39 right- and 16 left-sided tumors) involving the IVC, who underwent radical nephrectomy and tumor thrombectomy between 1983 and 2005 at a single institution in Japan. The level of thrombus was classified as follows: level I, infrahepatic; level II, intrahepatic; level III, suprahepatic; and level IV, extending to the atrium. Clinicopathological data from these patients were retrospectively reviewed to identify factors associated with survival. RESULTS: There were 11 and 18 patients who were diagnosed as having lymph node and distant metastases, respectively. Twenty-two patients had tumor thrombus in level I, 20 in level II, 10 in level III, and 3 in level IV. Pathological examinations demonstrated that 34 and 21 patients had clear cell carcinoma and non-clear cell carcinoma, respectively, 42, 9 and 4 were pT3b, pT3c and pT4, respectively, and 6, 35 and 14 were Grades 1, 2 and 3, respectively. Cancer-specific 1-, 3- and 5-year survival rates of these 55 patients were 74.5%, 51.4% and 30.3%, respectively. Among several factors examined, clinical stage (P = 0.047), lymph node metastasis (P = 0.016), histological subtype (P = 0.034) and tumor grade (P < 0.001) were significantly associated with cancer-specific survival by univariate analysis. Furthermore, multivariate analysis demonstrated clinical stage (P = 0.037) and tumor grade (P < 0.001) as independent predictors of cancer-specific survival irrespective of other significant factors identified by univariate analysis. CONCLUSIONS: In patients with RCC involving the IVC, biological aggressiveness characterized by tumor grade rather than tumor extension would have more potential prognostic importance; therefore, more intensive multimodal therapy should be considered in patients with high grade RCC with tumor thrombus extending into the IVC.  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