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   2387篇
  免费   134篇
  国内免费   11篇
耳鼻咽喉   35篇
儿科学   75篇
妇产科学   53篇
基础医学   360篇
口腔科学   170篇
临床医学   195篇
内科学   460篇
皮肤病学   55篇
神经病学   153篇
特种医学   44篇
外科学   315篇
综合类   4篇
预防医学   303篇
眼科学   34篇
药学   160篇
中国医学   15篇
肿瘤学   101篇
  2024年   2篇
  2023年   28篇
  2022年   39篇
  2021年   106篇
  2020年   50篇
  2019年   76篇
  2018年   81篇
  2017年   69篇
  2016年   70篇
  2015年   61篇
  2014年   99篇
  2013年   136篇
  2012年   187篇
  2011年   202篇
  2010年   109篇
  2009年   89篇
  2008年   134篇
  2007年   117篇
  2006年   102篇
  2005年   109篇
  2004年   103篇
  2003年   107篇
  2002年   78篇
  2001年   50篇
  2000年   43篇
  1999年   49篇
  1998年   14篇
  1997年   18篇
  1996年   11篇
  1995年   13篇
  1994年   10篇
  1993年   14篇
  1992年   22篇
  1991年   17篇
  1990年   20篇
  1989年   15篇
  1988年   15篇
  1987年   11篇
  1986年   10篇
  1985年   11篇
  1984年   2篇
  1983年   2篇
  1981年   2篇
  1979年   5篇
  1978年   3篇
  1976年   5篇
  1975年   3篇
  1971年   2篇
  1968年   2篇
  1958年   1篇
排序方式: 共有2532条查询结果,搜索用时 15 毫秒
71.
MYC is an oncogene involved in cell cycle regulation, cell growth arrest, cell adhesion, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function. It has been described as a key element of several carcinogenesis processes in humans. Many studies have shown an association between MYC deregulation and gastric cancer. MYC deregulation is also seen in gastric preneoplastic lesions and thus it may have a role in early gastric carcinogenesis. Several studies have suggested that amplification is the main mechanism of MYC deregulation in gastric cancer. In the present review, we focus on the deregulation of the MYC oncogene in gastric adenocarcinoma carcinogenesis, including its association with Helicobacterpylori (Hpylon] and clinical applications.  相似文献   
72.
Sport Sciences for Health - Muscular responses to training programs with the Nordic hamstring exercise (NHE) have been widely investigated to understand its preventive effects on muscle strain...  相似文献   
73.
J A Leal  J V May  B A Keel 《Endocrinology》1990,126(1):669-671
Alpha fetoprotein (AFP) is present at high concentrations in fetal fluids, certain neoplasias, and regenerating liver. Its physiological function remains largely unknown. Using a primary monolayer culture system, we investigated the proliferative activity of human (h) cord blood (CB) and highly purified AFP. hAFP, purified from hCB by Cibacron blue and immunoaffinity chromatography was homogeneous on SDS-PAGE and silver stain. Porcine granulosa cells from ovarian small follicles were cultured (25,000/cm2) for 2 days in medium (Ham's F-12:DMEM, 1:1) + 5% fetal calf serum (FCS) to facilitate attachment, followed by 6 days in medium containing: FCS, hCB or h amniotic fluid (1-20%)+/- EGF (10 ng/ml); or 0.25% plasma-derived serum (PDS) containing human low density lipoprotein (LDL, 25 ug/ml), +/- AFP (0.05-5 ug), and +/- EGF and IGF-I (10 ng/ml). In this system, single growth factors do not stimulate proliferation, a characteristic also exhibited by AFP. When combined with EGF, however, AFP dose-dependently increased proliferation to levels equal to that obtained with 10% FCS (2.3-fold increase vs PDS/LDL controls). When combined with EGF+IGF-I, AFP again dose-dependently increased proliferation to levels equal to that obtained with 10% FCS+EGF (6.7-fold increase vs controls). Purified human albumin used in place of AFP was not effective. TGF-a but not PDGF could replace the proliferative activity of EGF. These results suggest that AFP at physiological levels, although not itself mitogenic, can enhance the mitogenic activity of EGF and TGF-a and may function to modulate growth factor-mediated proliferation during development and neoplasia.  相似文献   
74.
The pilocarpine model in rodents reproduces the main features of mesial temporal lobe epilepsy related to hippocampus sclerosis (MTLE-HS) in humans. It has been demonstrated in this model that the phosphorylation of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluR1 subunit is increased 1 h after pilocarpine treatment. Moreover, alterations in the levels of glutamate transporters have been associated with chronic epilepsy in humans. Despite these studies, the profile of these changes has not yet been addressed. We analyzed the protein content and phosphorylation profile of the AMPA receptor GluR1 subunit by western blotting. We also used quantitative real-time polymerase chain reaction to analyze the expression of glial glutamate transporters and the N-methyl-d-aspartate receptor NR1 subunit in the hippocampus (Hip) and cerebral cortex (Ctx) at different time points after pilocarpine-induced status epilepticus (Pilo-SE) in male adult Wistar rats. Biochemical analysis was performed in the Hip and Ctx at 1, 3, 12 h (acute period), 5 days (latent period), and 50 days (chronic period) after Pilo-SE. Key findings include an increase in the phosphorylation of GluR1-Ser845 in the Ctx and GluR1-Ser831 in the Hip at different times during the acute period, and a decrease in the total content of the GluR1 subunit in the Ctx in the latent period. There was a down-regulation of the mRNA expression and protein levels of EAAT1 and EAAT2, and a decrease of the NR1 mRNA expression, in the Ctx during the latent period. Notably, during the chronic period, the EAAT2 mRNA expression and protein levels decreased while the NR1 mRNA levels increased in the Hip. Taken together, our findings suggest a time- and structure-dependent imbalance of glutamatergic transmission in response to Pilo-SE, which might be associated with either epileptogenesis or the seizure threshold in MTLE-HS.  相似文献   
75.
76.
Background Drooling is a major morbidity in several neurological diseases. Intraglandular botulinum neurotoxin (BoNT) injections have been used to manage this condition. However, by decreasing salivary flow, BoNT injections may result in an increased risk of caries and other oral adverse effects. In this study, we aimed to assess whether, in patients with drooling, intraglandular BoNT injections are associated with increased dental caries development, modifications on salivary composition (oral pH, buffering capacity and osmolality) and cariogenic bacterial load. Material and Methods We performed a systematic review, searching PubMed, CENTRAL, Web of Science, and Scopus for all experimental and observational studies reporting on adverse effects of intraglandular BoNT injections in patients with drooling. Primary study selection, quality assessment, and data extraction were independently performed by two researchers. No studies were excluded based on their language, publication status or date of publication. Studies’ quality was based on revised Cochrane Risk of Bias tools. Meta-analysis was not performed. Results We retrieved 1025 studies, of which 5 were included. Two studies were two randomized controlled trials and three quasi-experimental studies. None of the included studies found BoNT injections to be associated with dental caries development or with significant reductions in oral pH. One of the included primary studies even observed an increase in salivary buffer capacity. One study found an increase in Lactobacilli counts. As for the risk of bias, two studies were classified as having a critical risk, two as high risk and one as having some concerns. Conclusions Currently, there is no evidence that, in patients with drooling, BoNT injections associate with increased risk of dental caries or disturbances in oral pH or salivary buffering capacity. However, the included primary studies had important limitations and differences in their methodologies. Key words:Neurological diseases, drooling, sialorrhea, botulinum toxin, oral health, caries, saliva.  相似文献   
77.
To describe a new molar-incisor hypomineralization (MIH) severity scoring system (MIH-SSS) that focuses on the defects’ severity and to assess the sy  相似文献   
78.

Objective

To determine whether stratification of complexity models in congenital heart surgery (RACHS-1, Aristotle basic score and STS-EACTS mortality score) fit to our center and determine the best method of discriminating hospital mortality.

Methods

Surgical procedures in congenital heart diseases in patients under 18 years of age were allocated to the categories proposed by the stratification of complexity methods currently available. The outcome hospital mortality was calculated for each category from the three models. Statistical analysis was performed to verify whether the categories presented different mortalities. The discriminatory ability of the models was determined by calculating the area under the ROC curve and a comparison between the curves of the three models was performed.

Results

360 patients were allocated according to the three methods. There was a statistically significant difference between the mortality categories: RACHS-1 (1) - 1.3%, (2) - 11.4%, (3)-27.3%, (4) - 50 %, (P<0.001); Aristotle basic score (1) - 1.1%, (2) - 12.2%, (3) - 34%, (4) - 64.7%, (P<0.001); and STS-EACTS mortality score (1) - 5.5 %, (2) - 13.6%, (3) - 18.7%, (4) - 35.8%, (P<0.001). The three models had similar accuracy by calculating the area under the ROC curve: RACHS-1- 0.738; STS-EACTS-0.739; Aristotle- 0.766.

Conclusion

The three models of stratification of complexity currently available in the literature are useful with different mortalities between the proposed categories with similar discriminatory capacity for hospital mortality.  相似文献   
79.
Thirty-nine patients with acute cervical spine fractures and/or dislocations between C3 and C7 were submitted to an anterior approach using bone graft fixation without screw and plate systems and three required a preliminary posterior approach to reduce a dislocation. Graft dislodgement due to technical problems occurred at a rate of 7.7% postoperatively and 2.8% 1 month later. No redislodgement occurred. All fusions became solid after 3 months. Their progress was based on the Frankel scale, before surgery, at the moment of the discharge, and at 6 months follow-up. This experience shows how patients with an acute cervical injury can improve even when admitted late after trauma.  相似文献   
80.
TNF ligand superfamily member 12, also known as TNF-related weak inducer of apoptosis (TWEAK), acts through its receptor, fibroblast growth factor-inducible 14 (Fn14), to mediate several key pathologic processes involved in tissue injury relating to lupus nephritis. To explore the potential for renal protection in lupus nephritis by targeting this pathway, we introduced the Fn14 null allele into the MRL-lpr/lpr lupus mouse strain. At 26–38 weeks of age, female Fn14-knockout MRL-lpr/lpr mice had significantly lower levels of proteinuria compared with female wild-type MRL-lpr/lpr mice. Furthermore, Fn14-knockout mice had significantly improved renal histopathology accompanied by attenuated glomerular and tubulointerstitial inflammation. There was a significant reduction in glomerular Ig deposition in Fn14-knockout mice, despite no detectable differences in either serum levels of antibodies or splenic immune cell subsets. Notably, we found that the Fn14-knockout mice displayed substantial preservation of podocytes in glomeruli and that TWEAK signaling directly damaged barrier function and increased filtration through podocyte and glomerular endothelial cell monolayers. Our results show that deficiency of the Fn14 receptor significantly improves renal disease in a spontaneous lupus nephritis model through prevention of the direct injurious effects of TWEAK on the filtration barrier and/or modulation of cytokine production by resident kidney cells. Thus, blocking the TWEAK/Fn14 axis may be a novel therapeutic intervention in immune-mediated proliferative GN.  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