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   2930篇
  免费   141篇
  国内免费   10篇
耳鼻咽喉   20篇
儿科学   20篇
妇产科学   58篇
基础医学   337篇
口腔科学   123篇
临床医学   163篇
内科学   727篇
皮肤病学   131篇
神经病学   204篇
特种医学   148篇
外科学   443篇
综合类   6篇
预防医学   66篇
眼科学   69篇
药学   252篇
中国医学   8篇
肿瘤学   306篇
  2023年   22篇
  2021年   52篇
  2020年   39篇
  2019年   63篇
  2018年   62篇
  2017年   51篇
  2016年   47篇
  2015年   59篇
  2014年   71篇
  2013年   93篇
  2012年   133篇
  2011年   180篇
  2010年   85篇
  2009年   84篇
  2008年   154篇
  2007年   146篇
  2006年   143篇
  2005年   164篇
  2004年   131篇
  2003年   117篇
  2002年   133篇
  2001年   83篇
  2000年   91篇
  1999年   78篇
  1998年   27篇
  1997年   29篇
  1996年   25篇
  1995年   28篇
  1994年   20篇
  1993年   23篇
  1992年   42篇
  1991年   46篇
  1990年   40篇
  1989年   61篇
  1988年   58篇
  1987年   52篇
  1986年   39篇
  1985年   39篇
  1984年   31篇
  1983年   29篇
  1981年   10篇
  1980年   15篇
  1979年   28篇
  1978年   14篇
  1977年   14篇
  1976年   13篇
  1975年   10篇
  1974年   22篇
  1972年   17篇
  1971年   12篇
排序方式: 共有3081条查询结果,搜索用时 31 毫秒
1.
2.
3.
Mamushi bites cause swelling and pain that extend from the bitten site. The coagulopathic, anti-coagulopathic, and vasculopathic actions of mamushi venom result in various laboratory abnormalities, occasionally with muscular, renal, and other organ damage. We investigated the serum biomarkers that were associated with the pathogenesis of mamushi bites, focusing on markers related to tissue-damage and neutrophil activation. Twenty patients (one case of grade 2, 13 cases of grade 3, and six cases of grade 4 of severity) seen by us in one summer season were enrolled. Peripheral blood samples were taken from the patients on day 0, day 2, and day 7 after mamushi bites. In addition to routine blood examination, serum samples were subjected to enzyme-linked immunosorbent assay for citrullinated histone H3 (CitH3), interleukin (IL)-8, IL-17A, IL-22, vascular endothelial growth factor (VEGF), high mobility group box protein 1 (HMGB1), tumor necrosis factor (TNF)-α, and IL-33. Creatinine kinase (CK) values significantly correlated with prothrombin time (PT) levels, suggesting that muscular damage is associated with exaggerated coagulation and fibrinolysis. In the vast majority of patients, HMGB1, TNF-α, and IL-33 were under detection levels. Neutrophil counts did not correlate with PT or CK, indicating that the coagulation disorder and muscular damage were virtually independent of the neutrophil activation. The neutrophil number significantly correlated with CitH3, a representative marker of neutrophil extracellular traps. Moreover, there were significant correlations between neutrophil number, CitH3, IL-8, IL-22, and VEGF. Our study suggests that there are two major cascades in mamushi bites. One is an already characterized venom effect on coagulation, vessels, and muscles. In the other novel cascade, we propose that neutrophil activation with IL-8 leads to the production of IL-22 and VEGF. This sequential event may contribute to both vascular damage and repair.  相似文献   
4.
5.
Knee osteoarthritis (OA) is becoming more prevalent worldwide due to increases in the numbers of elderly and obese patients. Currently, pharmaceutical medicines used for the treatment of OA are for symptomatic therapy and therefore new therapeutic agents are needed. Kaempferia parviflora (KP) is a plant growing naturally in Southeast Asia and has various pharmacological effects including an anti-inflammatory effect, but no effect on OA has yet been reported. We therefore conducted a search for the effects KP and the active components of KP extract (KPE) exert on OA as well as its mechanism of action. Results from a study of KPE using the monoiodoacetic acid rat OA model revealed that KPE reduced the pain threshold and severity of osteoarthritic cartilage lesions. The mechanism of action and active components were then investigated using IL-1β-treated human knee-derived chondrocytes. KPE, as well as 5,7-dimethoxyflavone and 5,7,4′-trimethoxyflavone, which are key constituents of KPE and highly absorbable into the body, reduced the expression of matrix metalloproteinases (MMPs), which are the main extracellular matrix enzymes that degrade collagen within cartilage. As mentioned above, KPE acted to suppress OA and 5,7-dimethoxyflavone and 5,7,4′-trimethoxyflavone were shown to be involved as part of KPE’s mechanism that inhibits MMPs.  相似文献   
6.
Distraction osteogenesis is widely used for the treatment of craniofacial deformities. In patients with cleft lip and palate, distraction osteogenesis can be employed to repair the alveolar cleft. In this report, we describe the management of three cases of unilateral cleft lip and palate by interdental distraction osteogenesis. Interdental distraction osteogenesis of the maxillary bone was performed to reduce the width of the alveolar cleft in these patients in conjunction with orthodontic treatment. Tooth-tooth type distraction devices were fabricated and delivered at the same time as osteotomy. Distraction was continued until the midline of the dentition coincided with the facial midline, and until the width of the alveolar cleft was reduced to the width of lateral incisor or had closed. One month after distraction was complete, orthodontic treatment with an edgewise appliance was initiated, and neighboring teeth were moved into the newly created bone. A favorable treatment outcome was achieved in all three cases.  相似文献   
7.

Objectives

To investigate potential functions of transforming growth factor-beta (TGF-β) isoforms in maturation-stage ameloblasts during amelogenesis.

Methods

In vivo activation of TGF-β was characterized by using matrix metalloproteinase 20 null (Mmp20-/-) and wild-type (Mmp20+/+) mice. Using mHAT9d cells cultured in the presence of each TGF-β isoform, (1) cell proliferation was determined by MTS assay, (2) immunostaining with anti-cleaved caspase-3 monoclonal antibody was performed and apoptotic indices were measured, (3) gene expression was analyzed by RT-qPCR, and (4) the uptake of amelogenin into mHAT9d cells was directly observed using a fluorescence microscope.

Results

TGF-β1 and TGF-β3 were present in the enamel matrix of developing teeth which were activated by MMP20 in vivo. A genetic study revealed that the three TGF-β isoforms upregulate kallikrein 4 (KLK4) mRNA levels but downregulate carbonic anhydrase II. Moreover, TGF-β1 and TGF-β2 significantly upregulated the mRNA level of amelotin, whereas TGF-β3 dramatically downregulated the mRNA levels of odontogenic ameloblast-associated protein (ODAM), family with sequence similarity 83 member H (FAM83H), and alkaline phosphatase (ALP). Immunostaining analysis showed that the apoptosis of mHAT9d cells is induced by three TGF-β isoforms, with TGF-β3 being most effective. Both TGF-β1 and TGF-β3 induced endocytosis of amelogenin.

Conclusions

We propose that TGF-β is regulated in an isoform-specific manner to perform multiple biological functions such as gene expression related to the structure of basal lamina/ameloblasts, mineral ion transport, apoptosis, and endocytosis in maturation-stage ameloblasts.  相似文献   
8.

Background

Immediately after cleft lip repair, breastfeeding and bottle-feeding are generally restricted to avoid placing tension on the surgical incision. However, no consensus about feeding methods after cleft lip repair has been reached. The objective of this systematic review was to examine the impact of breastfeeding and/or bottle-feeding on surgical wound dehiscence after cleft lip repair in infants.

Material and methods

We searched PubMed, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Mednar from October to November 2017. Two reviewers independently assessed eligibility for inclusion and checked critical appraisal of the study quality.

Results

Three randomized controlled trials and two cohort studies involving 342 infants were included in this review. Two cases of surgical wound dehiscence occurred in the control group of alternative feeding. In three of five studies, surgical wound dehiscence did not occur in either the intervention or control group within the first week postoperatively.

Conclusions

This review showed no increased risk of surgical wound dehiscence in infants with breastfeeding and/or bottle-feeding after cleft lip repair compared with infants with alternative feeding methods. It may not be necessary to restrict breastfeeding and/or bottle-feeding immediately after cleft lip repair.  相似文献   
9.
Hyaluronan (HA) exists in various living tissues as one of the major matrix macromolecules, and is well known to play an integral role in cell differentiation and proliferation. The present study was conducted to elucidate whether or not the proliferation of periodontal ligament (PDL) cells are affected specifically by the degradation of HA by hyaluronidasze (HAase). Human PDL fibroblasts were isolated and cultured with and without 15-150U/ml bovine testicular HAase from 1 to 11 days after seeding. The cells were also cultured with anti-CD44 antibody of 2 microg/ml. For the control against the anti-CD44 antibody treatment, 2 microg/ml IgG was used. The HA-dependent pericellular matrix was visualized by particle-exclusion assay. The number of cells was counted by MTT assay during the proliferation. The mRNA levels of HA synthases (HASs), HAases (HYALs) and CD44s were examined by a quantitative real-time PCR analysis. The cell proliferation was inhibited by the treatment with HAase and anti-CD44 antibody in cultured PDL fibroblasts. HASs mRNAs were down-regulated, whereas HYALs mRNAs were up-regulated significantly by the treatment with HAase and anti-CD44 antibody. The CD44s mRNA level exhibited no significant changes. These results suggest that HA may contribute to modulate the proliferation of cultured human PDL cells through a CD44-mediated mechanism.  相似文献   
10.
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