全文获取类型
收费全文 | 63244篇 |
免费 | 4873篇 |
国内免费 | 1735篇 |
专业分类
耳鼻咽喉 | 833篇 |
儿科学 | 1185篇 |
妇产科学 | 2213篇 |
基础医学 | 8009篇 |
口腔科学 | 1160篇 |
临床医学 | 6780篇 |
内科学 | 11761篇 |
皮肤病学 | 1186篇 |
神经病学 | 3955篇 |
特种医学 | 2605篇 |
外国民族医学 | 6篇 |
外科学 | 8515篇 |
综合类 | 4186篇 |
现状与发展 | 7篇 |
一般理论 | 11篇 |
预防医学 | 3419篇 |
眼科学 | 1394篇 |
药学 | 5297篇 |
20篇 | |
中国医学 | 1673篇 |
肿瘤学 | 5637篇 |
出版年
2023年 | 462篇 |
2022年 | 932篇 |
2021年 | 2142篇 |
2020年 | 1292篇 |
2019年 | 1617篇 |
2018年 | 1995篇 |
2017年 | 1515篇 |
2016年 | 1565篇 |
2015年 | 2324篇 |
2014年 | 2914篇 |
2013年 | 3397篇 |
2012年 | 4819篇 |
2011年 | 4692篇 |
2010年 | 2985篇 |
2009年 | 2613篇 |
2008年 | 3541篇 |
2007年 | 3539篇 |
2006年 | 3389篇 |
2005年 | 3127篇 |
2004年 | 2828篇 |
2003年 | 2709篇 |
2002年 | 2351篇 |
2001年 | 1843篇 |
2000年 | 1609篇 |
1999年 | 1335篇 |
1998年 | 551篇 |
1997年 | 456篇 |
1996年 | 416篇 |
1995年 | 377篇 |
1994年 | 348篇 |
1993年 | 242篇 |
1992年 | 711篇 |
1991年 | 582篇 |
1990年 | 531篇 |
1989年 | 485篇 |
1988年 | 421篇 |
1987年 | 423篇 |
1986年 | 355篇 |
1985年 | 295篇 |
1984年 | 229篇 |
1983年 | 191篇 |
1982年 | 114篇 |
1981年 | 122篇 |
1980年 | 99篇 |
1979年 | 205篇 |
1978年 | 161篇 |
1977年 | 103篇 |
1976年 | 110篇 |
1975年 | 102篇 |
1974年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
991.
992.
Ya-Wen Lu Yi-Lin Tsai Ruey-Hsing Chou Chin-Sung Kuo Chun-Chin Chang Po-Hsun Huang Shing-Jong Lin 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2021,31(5):1509-1515
Background & aimsSarcopenia is a clinical syndrome that features muscle atrophy and weakness, and has been associated with cardiovascular events and poor clinical outcomes. Recently, the sarcopenia index (SI) was developed as a simple screening tool based upon the serum creatinine to cystatin C (CysC) ratio. We investigated the association between SI and the prevalence of major adverse cardiovascular events (MACE) in patients with obstructive CAD.Methods & ResultsBetween January 2010 and December 2018, patients with angina pectoris and obstructive CAD requiring coronary artery intervention were enrolled. Serum levels of CysC and other biomarkers were assessed. Patients were divided into two groups according to the SI ([Cr/CysC] x 100). Demographic characteristics and clinical outcomes of the two groups were evaluated. A total of 427 patients (79.6% men, mean age 69.55 ± 12.04 years) were enrolled. Patients with SI < 120 (n = 214, 28%) were older, more likely to be of the female gender, and to have more hypertension and congestive heart failure (all p < 0.05). The prevalence of major adverse cardiovascular events (MACE) composed of myocardial infarction, stroke, and all-cause mortality was higher in patients with lower SI (p = 0.026). After adjusting for potential confounding factors, multivariate Cox regression (hazard ratio 2.08, p = 0.045) and Kaplan–Meier analyses (log-rank p = 0.0371) revealed that lower SI was significantly associated with a higher prevalence of MACE.ConclusionsSerum creatinine to cystatin C ratio (SI) may be a useful surrogate marker to predict the future prevalence of MACE in patients with obstructive CAD. 相似文献
993.
Chi-Ruei Huang Chung-Ta Lee Kwang-Yu Chang Wen-Chang Chang Yao-Wen Liu Jenq-Chang Lee Ben-Kuen Chen 《Oncotarget》2015,6(13):11530-11546
The aryl hydrocarbon receptor nuclear translocator (ARNT) is broadly involved in regulating tumorigenesis by inducing genes that are involved in tumor growth and angiogenesis. Tumorigenesis usually involves normoxic conditions. However, the role of ARNT in tumor metastasis during normoxia remains unclear. Here, we demonstrate that ARNT protein levels were decreased in late-stage human colorectal cancer using immunohistochemical analysis. Down-regulation of ARNT protein promoted cancer cell migration and invasion, which was mediated by activation of the fibronectin/integrin β1/FAK signaling axis. In addition, the enhancement of migration and invasion in ANRT knockdown cells was blocked when ARNT was restored in the cells. In xenografts in severe combined immunodeficiency mice, tumor growth was significantly inhibited in the ARNT-knockdown condition. However, the tail-vein injection animal model revealed that the depletion of ARNT-induced metastatic lung colonies was further enhanced when ARNT expression was recovered post-injection. Interestingly, chemotherapeutic drugs inhibited ARNT expression and promoted the invasion of residual tumor cells. These results suggest that ARNT may play a positive role during tumor growth (either in early-stage tumor growth or in organ metastases), but plays a negative role in tumor migration and invasion. Therefore, the efficiency of ARNT-targeted therapy during different cancer stages should be carefully evaluated. 相似文献
994.
995.
Jae Won Chang Su A. Park Ju‐Kyeong Park Jae Won Choi Yoo‐Suk Kim Yoo Seob Shin Chul‐Ho Kim 《Artificial organs》2014,38(6):E95-E105
Three‐dimensional printing has come into the spotlight in the realm of tissue engineering. We intended to evaluate the plausibility of 3D‐printed (3DP) scaffold coated with mesenchymal stem cells (MSCs) seeded in fibrin for the repair of partial tracheal defects. MSCs from rabbit bone marrow were expanded and cultured. A half‐pipe‐shaped 3DP polycaprolactone scaffold was coated with the MSCs seeded in fibrin. The half‐pipe tracheal graft was implanted on a 10 × 10‐mm artificial tracheal defect in four rabbits. Four and eight weeks after the operation, the reconstructed sites were evaluated bronchoscopically, radiologically, histologically, and functionally. None of the four rabbits showed any sign of respiratory distress. Endoscopic examination and computed tomography showed successful reconstruction of trachea without any collapse or blockage. The replaced tracheas were completely covered with regenerated respiratory mucosa. Histologic analysis showed that the implanted 3DP tracheal grafts were successfully integrated with the adjacent trachea without disruption or granulation tissue formation. Neo‐cartilage formation inside the implanted graft was sufficient to maintain the patency of the reconstructed trachea. Scanning electron microscope examination confirmed the regeneration of the cilia, and beating frequency of regenerated cilia was not different from those of the normal adjacent mucosa. The shape and function of reconstructed trachea using 3DP scaffold coated with MSCs seeded in fibrin were restored successfully without any graft rejection. 相似文献
996.
998.
999.
1000.
Kevin E. Bennet Kendall H. Lee James N. Kruchowski Su-Youne Chang Michael P. Marsh Alexander A. Van Orsow Aurelio Paez Felicia S. Manciu 《Materials》2013,6(12):5726-5741
Building on diamond characteristics such as hardness, chemical inertness and low electron emission threshold voltage, the current microscopic, spectroscopic and voltammetric investigations are directed towards improving the properties of electrode coating materials for their future use in clinical studies of deep brain stimulation via fast-scan cyclic voltammetry (FSCV). In this study we combine the capabilities of confocal Raman mapping in providing detailed and accurate analysis of local distributions of material constituents in a series of boron-doped polycrystalline diamond films grown by chemical vapor deposition, with information from the more conventional techniques of scanning electron microscopy (SEM) and infrared absorption spectroscopy. Although SEM images show a uniform distribution of film crystallites, they have the limitation of being unable to differentiate the distribution of boron in the diamond. Values of 1018–1021 atoms/cm3 of boron content have been estimated from the absorption coefficient of the 1290 cm−1 infrared absorption band and from the 500 cm−1 Raman vibration. The observed accumulation of boron atoms and carbon sp2 impurities at the grain boundaries suggests that very high doping levels do not necessarily contribute to improvement of the material’s conductivity, corroborating with voltammetric data. FSCV results also indicate an enhanced stability of analyte detection. 相似文献