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   187864篇
  免费   17558篇
  国内免费   8398篇
耳鼻咽喉   2380篇
儿科学   4223篇
妇产科学   2163篇
基础医学   34499篇
口腔科学   5666篇
临床医学   14067篇
内科学   25854篇
皮肤病学   4896篇
神经病学   10862篇
特种医学   4243篇
外国民族医学   118篇
外科学   17023篇
综合类   27905篇
现状与发展   49篇
预防医学   5606篇
眼科学   3703篇
药学   15745篇
  28篇
中国医学   5816篇
肿瘤学   28974篇
  2024年   269篇
  2023年   2801篇
  2022年   3828篇
  2021年   7106篇
  2020年   6240篇
  2019年   6306篇
  2018年   6444篇
  2017年   6598篇
  2016年   6684篇
  2015年   7650篇
  2014年   11158篇
  2013年   12227篇
  2012年   10488篇
  2011年   11889篇
  2010年   9863篇
  2009年   9465篇
  2008年   9858篇
  2007年   10022篇
  2006年   9086篇
  2005年   8468篇
  2004年   7505篇
  2003年   6450篇
  2002年   5208篇
  2001年   4502篇
  2000年   3736篇
  1999年   3359篇
  1998年   3156篇
  1997年   2896篇
  1996年   2587篇
  1995年   2299篇
  1994年   2006篇
  1993年   1668篇
  1992年   1329篇
  1991年   1271篇
  1990年   980篇
  1989年   922篇
  1988年   865篇
  1987年   696篇
  1986年   660篇
  1985年   927篇
  1984年   889篇
  1983年   586篇
  1982年   637篇
  1981年   543篇
  1980年   444篇
  1979年   353篇
  1978年   248篇
  1977年   193篇
  1976年   156篇
  1975年   81篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.

Background

Since recent reports have shown that (-)-Epigallocatechin-3-gallate (EGCG) could be used for treating proliferative and inflammatory disorders, we explored its use for the management of corneal chemical burns.

Materials and methods

Initially, EGCG was assayed on the rabbit corneal epithelial cell line RCE1(5T5) to establish the best testing conditions, and to avoid unwanted outcomes in the experimental animals. Then, we studied its effects on cell proliferation, cell cycle progression and cell differentiation. Afterwards, we instilled EGCG in experimental grade II corneal alkali burns in mice, three times a day up to 21 days, and evaluated by slit lamp examination and histological sections of corneal epithelial, corneal endothelial and stromal edema, as well as the presence of inflammatory cells and neovascularization.

Results

EGCG reduced cell growth and led to a decline in the proportion of proliferative cells in a concentration dependent manner. At 10 μM, EGCG promoted cell differentiation, an effect not related with apoptosis or cytotoxicity. When 10 μM EGCG was instilled in corneal alkali burns in mice three times a day up to 21 days, EGCG significantly reduced corneal opacity and neovascularization. The improved clinical appearance of the cornea was associated to a controlled epithelial growth; epithelial morphology was similar to that observed in normal epithelium and contrasted with the hyperproliferative, desquamating epithelium observed in control burn wounds. EGCG reduced corneal, stromal and endothelial edema, and wound inflammation.

Conclusion

This work constitutes the first evidence for the use of EGCG in the acute phase of a corneal alkali burn, representing a possible novel alternative to improve patient outcomes as an add-on therapy.  相似文献   
63.
64.
Immune checkpoint inhibitors are molecules that increase the endogenous immune response against tumors. They have revolutionized the field of oncology. Since their initial approval for the treatment of advanced melanoma, their use has expanded to the treatment of several other advanced cancers. Unfortunately, immune checkpoint inhibitors have also been associated with the emergence of a new subset of autoimmune-like toxicities, known as immune-related adverse events. These toxicities differ depending on the agent, malignancy, and individual susceptibilities. Although the skin and colon are most commonly involved, any organ may be affected, including the liver, lungs, kidneys, and heart. Most of these toxicities are diagnosed by excluding other secondary infectious or inflammatory causes. Corticosteroids are commonly used for treatment of moderate and severe immune-related adverse events, although additional immunosuppressive therapy may occasionally be required. The occurrence of immune-related toxicities may require discontinuation of immunotherapy, depending on the specific toxicity and its severity. In this article, we provide a focused review to familiarize practicing clinicians with this important topic given that the use of immune checkpoint inhibitors continues to increase.  相似文献   
65.
66.
Using JEG-3 and BeWo cells, we examined the effect of “real life” mixtures of polycyclic aromatic hydrocarbons (PAHs), at doses reported in maternal blood (Mix I) and in placental tissue (Mix II), on human chorionic gonadotropin (hCG), placental lactogen (hPL) and placental growth factor (hPLGF) secretion, protein expression and immunolocalization. Additionally, the action of PAH mixtures on basal and hormone-stimulated matrix metalloproteinase-2 (MMP-2), MMP-9 and vascular endothelial growth factor (VEGF) protein expression was evaluated. Under basal conditions, the PAH mixtures increased hCG and decreased hPLGF levels in both cell lines, while hPL expression was stimulated in JEG-3 and inhibited in BeWo. There was no effect on the MMP-2/MMP-9 ratio or VEGF expression. In hormone-stimulated cells, PAH mixtures changed the MMP-2/MMP-9 ratio in JEG-3 cells in favor of MMP-9, while in BeWo MMP-2 was favored. The effect on VEGF expression was cell specific and dependent on the mixture. In hCG-treated cells, only Mix II inhibited VEGF expression in JEG-3 cells. Neither PAH mixtures affected this protein in BeWo cells. In hPL-treated cells, Mix I had a stimulatory effect in JEG-3 cells, while Mix II exerted an inhibitory effect in BeWo cells. In hPLGF-treated cells, Mix II decreased in JEG-3 cells, but in BeWo cells, both mixtures increased VEGF expression. Considering that the evaluated protein hormones play crucial roles in angiogenesis and neovascularization in the placenta, “real life” PAH mixtures by disrupting protein hormones levels, the MMP-2/MMP-9 ratio and VEGF expression can lead to insufficiency and many pregnancy-related disorders.  相似文献   
67.
In the United States, renal cell carcinoma (RCC) incidence and the prevalence of obesity, an established risk factor for RCC, have been increasing for several decades. RCC is more common among older individuals. We sought to quantify the contribution of excess adiposity to the rising incidence of RCC among individuals 60 years or older. National Institutes of Health-American Association of Retired Persons Diet and Health Study data (n = 453 859 participants, enrolled in 1995-1996, age at enrollment 50-71 years) were used to estimate multivariable-adjusted hazard ratios (HRs) for RCC across body mass index categories and HRs associated with smoking. Population attributable fractions (PAFs) were calculated using estimated HRs and annual overweight/obesity prevalence from the National Health Interview Survey (1985-2008). PAF estimates were combined with RCC incidence from Surveillance, Epidemiology and End Results-13 to calculate annual percent changes in RCC incidence attributable (and unrelated) to overweight/obesity. We found that between 1995 and 2018, among individuals aged 60 years and older, PAF for overweight/obesity increased from 18% to 29% for all RCCs. In comparison, the PAF for smoking declined from 12% to 9%. RCC incidence increased 1.8% per year (95% confidence interval [CI] 1.5%-2.1%) overall, while RCC incidence attributable to overweight/obesity increased 3.8% per year (95%CI 3.5%-4.2%) and RCC incidence unrelated to overweight/obesity increased 1.2% per year (95% CI 0.9%-1.4%). In conclusion, overweight/obesity appears to have contributed importantly to the rising incidence of RCC in the United States since the mid-1990s. Public health interventions focused on reducing overweight and obesity could help substantially in curbing this trend.  相似文献   
68.
BackgroundSurgical resection is recommended for patients with resectable acinar cell carcinoma (ACC). The aim of this study was to investigate the clinical characteristics and surgical outcomes of resectable ACC in comparison to pancreatic ductal adenocarcinoma (PDAC).MethodA retrospective analysis was performed on all patients who consecutively underwent radical resection with pathologically confirmed ACC and PDAC from December 2011 to December 2018. Clinicopathologic characteristics and follow-up information were analyzed. A 1:3 propensity score matching (PSM) method was used to minimize the bias between ACC and PDAC.ResultsA total of 26 patients with ACC and 1351 with PDAC were included. Compared to PDAC, ACC tended to be larger (4.5 vs. 3.0 cm; p < 0.001) and more frequently located in the pancreatic body/tail (61.5% vs. 36.6%, p = 0.009), with lower total bilirubin levels, lower neutrophil lymphocyte ratio (NLR) levels and lower carbohydrate antigen 19-9 (CA19-9) levels and carcinoembryonic antigen (CEA) levels. There was no difference in postoperative morbidities in patients with ACC and PDAC. The median OS and RFS were longer in ACC when compared to PDAC (OS: 43.5 mo vs. 19.0 mo, p = 0.004; RFS: 24.5 mo vs. 11.6 mo, p = 0.023). After the 1:3 PSM, ACC remained to be a better histological type for OS (p = 0.024), but had comparable RFS with PDAC (p = 0.164).ConclusionPatients with ACC after radical resection had better OS than that with PDAC. However, ACC is also an aggressive tumor with a similar trend of RFS with PDAC after the matching, necessitating the multidisciplinary treatment for resectable ACC disease.  相似文献   
69.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
70.
皮肤鳞状细胞癌是具有发病率高、发展快、可转移、易误诊等特点的一种恶性肿瘤,对人类的健康造成威胁。随着中医的发展和现代医学实验研究技术的进步,中医药在皮肤鳞状细胞癌的现代研究方面也取得一定成果。目前临床上治疗鳞状细胞癌多采取手术及药物化疗等,因不良反应的存在,患者接受度低。中药具有多靶点、安全性高、不良反应少等优势,在治疗皮肤鳞状细胞癌中中医具有一定优势,本文将围绕中药单体、中药复方,以及针灸在治疗皮肤鳞状细胞癌的研究进展展开论述和思考。  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