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   2768篇
  免费   157篇
  国内免费   14篇
耳鼻咽喉   6篇
儿科学   139篇
妇产科学   57篇
基础医学   315篇
口腔科学   38篇
临床医学   143篇
内科学   724篇
皮肤病学   24篇
神经病学   109篇
特种医学   167篇
外科学   613篇
综合类   14篇
预防医学   68篇
眼科学   116篇
药学   151篇
中国医学   3篇
肿瘤学   252篇
  2023年   23篇
  2022年   67篇
  2021年   97篇
  2020年   39篇
  2019年   72篇
  2018年   81篇
  2017年   65篇
  2016年   69篇
  2015年   100篇
  2014年   123篇
  2013年   128篇
  2012年   205篇
  2011年   244篇
  2010年   122篇
  2009年   120篇
  2008年   154篇
  2007年   220篇
  2006年   168篇
  2005年   167篇
  2004年   170篇
  2003年   138篇
  2002年   132篇
  2001年   16篇
  2000年   20篇
  1999年   24篇
  1998年   26篇
  1997年   13篇
  1996年   18篇
  1995年   21篇
  1994年   19篇
  1993年   13篇
  1992年   9篇
  1991年   6篇
  1990年   3篇
  1989年   11篇
  1988年   2篇
  1987年   6篇
  1986年   2篇
  1985年   2篇
  1983年   3篇
  1982年   3篇
  1981年   4篇
  1979年   2篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
  1972年   1篇
  1966年   1篇
  1964年   1篇
  1963年   1篇
排序方式: 共有2939条查询结果,搜索用时 15 毫秒
101.
Background Mucus is an important factor in the physiological defense mechanism of the gastrointestinal tract. We have reported that two distinct antigenicities reacting with anti-mucin monoclonal antibodies (mAbs), HCM31 and RGM26, emerged in epithelial cells regenerating from acetic acid-induced gastric damage in the rat. Here, we examined whether the expression of specific mucins occurred during the healing stage of acute gastric mucosal lesions, and what was the principal alteration of the mucus in the regenerating process of gastric epithelia from slight mucosal lesions.Methods Eight-week-old male Wistar rats were used. The animals were administered 0.6N hydrochloric acid, or 0.5% carboxymethyl cellulose sodium salt into their stomachs. Twenty-four, 48, and 72h after the HCl administration, their stomachs were removed. Immunohistochemical observation was performed after staining with the mAbs, RGM21, RGM26, HIK1083, or HCM31.Results Twenty-four hours after the administration of HCl, mucous cells stained with RGM26 emerged in the deeper area of the surface epithelial cells in the damaged corpus mucosa. After 48h, HCM31-positive cells were noted in the epithelial cells where the mucosal damage reached more deeply.Conclusions The appearance of specific mucin species was observed in the regenerating epithelia of the rat during the healing process from acute gastric mucosal damage.  相似文献   
102.
OBJECTIVE: Vasopressin (AVP) is reported to be an important factor for regulating cortisol secretion in patients with Cushing's syndrome due to ACTH-independent macronodular adrenocortical hyperplasia (AIMAH). Recently, there have been several case reports of subclinical Cushing's syndrome due to AIMAH, in which the pathophysiological role of AVP has been unknown. The aim was to conduct an extensive investigation of AVP in the autonomous secretion of cortisol in subclinical Cushing's syndrome due to AIMAH. PATIENTS AND MEASUREMENTS: Five cases of AIMAH with subclinical Cushing's syndrome underwent prospective study including physical examination, imaging (MRI, CT and 131I-adosterol scintigraphy) and endocrinological evaluation that comprised basal plasma cortisol levels and urinary excretions of steroid metabolites, a dexamethasone suppression test and an AVP stimulation test. In case 1, left adrenalectomy was performed and the pathological diagnosis of AIMAH was established. An in vitro experiment using the cultured AIMAH adrenal cells was conducted to investigate cortisol secretion and expression of the V1-AVP receptor, mRNA by RT-PCR. RESULTS: All five cases were discovered incidentally to have bilateral adrenal nodules. Imaging by MRI and CT revealed large multinodular lesions in both adrenal glands, which showed positive uptake on 131I-adosterol scintigraphy. Although the basal values of plasma cortisol and urinary excretions of steroid metabolites were within normal limits, autonomous secretion of cortisol was assumed to occur because of lack of suppression during dexamethasone suppression. The five patients had no overt signs of Cushing's syndrome, and they were therefore diagnosed with subclinical Cushing's syndrome due to AIMAH. In all five patients, AVP stimulated cortisol secretion in vivo, whereas desmopressin acetate failed to affect cortisol secretion. In case 1, AVP stimulated cortisol secretion from cultured AIMAH adrenal cells, but this secretion had no relationship with cAMP production. In addition, over-expression of V1-AVP receptor mRNA in AIMAH tissue was determined by RT-PCR. CONCLUSION: Patients with subclinical Cushing's syndrome due to AIMAH commonly exhibit cortisol responsiveness to AVP, and this is probably mediated through activation of overexpressed V1-AVP receptors.  相似文献   
103.
There are few reports of central pontine myelinolysis after living donor liver transplantation. A 59-year-old male received a right liver graft from his daughter for hepatitis B-related liver cirrhosis. Methylprednisolone and tracrolimus were used for immunosuppression. Dysarthria and dysphasia were noted on the second postoperative day. Brain magnetic resonance image taken on the 9th postoperative day revealed a hyperintense area at the center of his pons in T2-weighted images. The symptoms improved spontaneously 1 month after the operation. Central pontine myelinolysis should be included in the differential diagnosis when neurologic manifestations are observed after living donor liver transplantation.  相似文献   
104.
105.

Background

Carotid artery stenting (CAS) requires follow-up imaging to assess in-stent restenosis (ISR). This study aimed to determine whether non-enhanced magnetic resonance angiography (NE-MRA) is useful for evaluating ISR.

Method

Between 2009 and 2013, we performed 118 consecutive CAS procedures using the Precise stent (n?=?78) and the Carotid Wallstent (n?=?40). We reviewed 1.5 T NE-MRA and examined visualization of the stent lumen and the degree of ISR if present. Other imaging modalities were used as references.

Results

NE-MRA performed just after CAS was not able to visualize the stent lumen in all patients because of metal artifacts. In the Carotid Wallstent group, follow-up NE-MRA was available in 22 patients. The stent lumen was visible more than three months after CAS in all patients. Among them, >40 % ISR was observed by other modalities in eight lesions. The degree of restenosis measured by NE-MRA (y%) had a linear relationship with that measured by conventional angiography (x%) (y?=?0.97x-0.4, r?=?0.79, P?=?0.021). In one case among 17 without ISR (6 %), NE-MRA showed false ISR. In the Precise stent group, NE-MRA did not visualize the stent lumen in the follow-up period.

Conclusions

NE-MRA can visualize the stent lumen in the Carotid Wallstent more than three months after CAS, but not in the Precise stent at follow-up. This delayed visualization might depend on endothelialization of the stent lumen. The degree of ISR measured by NE-MRA is comparable to that by conventional angiography. NE-MRA can evaluate ISR after CAS with the Carotid Wallstent (100 % sensitivity and 94 % specificity).  相似文献   
106.
107.

Objective

Metformin and glucagon like peptide-1 (GLP-1) prevent diabetic cardiovascular complications and atherosclerosis. However, the direct effects on hyperglycemia-induced oxidative stress in endothelial cells are not fully understood. Thus, we aimed to evaluate the effects of metformin and a GLP-1 analog, liraglutide on high glucose-induced oxidative stress.

Methods

Production of reactive oxygen species (ROS), activation of protein kinase C (PKC) and NAD(P)H oxidase, and changes in signaling molecules in response to high glucose exposure were evaluated in human aortic endothelial cells with and without treatment of metformin and liraglutide, alone or in combination. PKC-NAD(P)H oxidase pathway was assessed by translocation of GFP-fused PKCβ2 isoform and GFP-fused p47phox, a regulatory subunit of NAD(P)H oxidase, in addition to endogenous PKC phosphorylation and NAD(P)H oxidase activity.

Results

High glucose-induced ROS overproduction was blunted by metformin or liraglutide treatment, with a further decrease by a combination of these drugs. Exposure to high glucose caused PKCβ2 translocation and a time-dependent phosphorylation of endogenous PKC but failed to induce its translocation and phosphorylation in the cells treated with metformin and liraglutide. Furthermore, both drugs inhibited p47phox translocation and NAD(P)H oxidase activation, and prevented the high glucose-induced changes in intracellulalr diacylglycerol (DAG) level and phosphorylation of AMP-activated protein kinase (AMPK). A combination of these drugs further enhanced all of these effects.

Conclusions

Metformin and liraglutide ameliorate high glucose-induced oxidative stress by inhibiting PKC-NAD(P)H oxidase pathway. A combination of these two drugs provides augmented protective effects, suggesting the clinical usefulness in prevention of diabetic vascular complications.  相似文献   
108.
The significance of switching of the nucleos(t)ide analog used to treat patients with hepatitis B virus (HBV) from entecavir (ETV) to tenofovir alafenamide fumarate (TAF) is uncertain. The subjects of this study were 159 patients with HBV who received treatment with ETV followed by TAF. Among these patients, serial changes in the HBV marker levels were monitored in 92 patients in whom the serum HBsAg levels were ≥100 IU/mL during the 48-week period immediately before and after the switching. A questionnaire survey for medication compliance was performed in 127 patients. The serum HBsAg levels (log IU/mL) decreased by 0.041 during the ETV treatment period and by 0.068 during the TAF administration period. The degree of reduction was higher during the TAF administration period than during the ETV administration period in patients without cirrhosis (P = .030), patients with genotype B HBV (P = .014), and patients with undetectable serum HBcrAg (P = .038). Multivariate analysis revealed the HBV genotype (B vs C; odds ratio, 3.400; P = .025) and serum aspartate aminotransferase level (every 1+; 1.111; P = .015) at the time of switching as factors influencing the treatment efficacy. Thirty-six patients (28%) responded that the number of days that they forgot to take the drug decreased after the drug switching, and 77 patients (61%) reported feeling satisfied with the drug switching. Switching of the nucleos(t)ide analog used from ETV to TAF may be useful in the treatment of patients with HBV infection, as it is associated with both a decrease in the serum HBsAg level and improvement of the medication compliance.  相似文献   
109.

Purpose

The aim of this study was to evaluate the efficacy of mesenchymal stem cells (MSCs) in a nitrofen-induced congenital diaphragmatic hernia (CDH) rat model.

Methods

Pregnant rats were exposed to nitrofen on embryonic day 9.5 (E9.5). MSCs were isolated from the enhanced green fluorescent protein (eGFP) transgenic rat lungs. The MSCs were transplanted into the nitrofen-induced E12.5 rats via the uterine vein, and the E21 lung explants were harvested. The study animals were divided into three: the control group, the nitrofen-induced left CDH (CDH group), and the MSC-treated nitrofen-induced left CDH (MSC-treated CDH group). The specimens were morphologically analyzed using HE and immunohistochemical staining with proliferating cell nuclear antigen (PCNA), surfactant protein-C (SP-C), and α-smooth muscle actin.

Results

The alveolar and medial walls of the pulmonary arteries were significantly thinner in the MSC-treated CDH group than in the CDH group. The alveolar air space areas were larger, while PCNA and the SP-C positive cells were significantly higher in the MSC-treated CDH group, than in the CDH group. MSC engraftment was identified on immunohistochemical staining of the GFP in the MSC-treated CDH group.

Conclusions

MSC transplantation potentially promotes alveolar and pulmonary artery development, thereby reducing the severity of pulmonary hypoplasia.  相似文献   
110.
Objective In this study, we investigated whether and how the COVID-19 pandemic affected glycemic control and blood pressure (BP) control in patients with diabetes mellitus (DM). Methods DM patients whose HbA1c level was measured regularly before and after the declaration of a state of emergency were included in this study. Some patients were given questionnaires about changes in their lifestyle to determine the factors affecting glycemic control and BP control. Results The median HbA1c level of the 804 patients increased significantly from 6.8% before the state of emergency to 7.1% and 7.0% during and after the state of emergency, respectively. This was in contrast to the decrease one year earlier due to seasonal variations. In the 176 patients who responded to the questionnaire, the HbA1c level also increased significantly during and after the state of emergency. The worsening of glycemic control was more pronounced in the group that had achieved HbA1c of <7% before the state of emergency than in those with higher values. Unlike the rise in HbA1c, the BP did not rise during the state of emergency but did rise significantly afterwards. There was no marked decrease in HbA1c or BP after the state of emergency, even in patients who responded that they were much more careful with their diet, ate less, or exercised more. Conclusions The COVID-19 pandemic worsened glycemic control and BP control, even in patients who perceived no marked change in their diet or exercise, suggesting that more active lifestyle guidance is necessary for good treatment of DM patients.  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