全文获取类型
收费全文 | 6333篇 |
免费 | 781篇 |
国内免费 | 457篇 |
出版年
2023年 | 73篇 |
2022年 | 91篇 |
2021年 | 272篇 |
2020年 | 202篇 |
2019年 | 310篇 |
2018年 | 257篇 |
2017年 | 228篇 |
2016年 | 265篇 |
2015年 | 357篇 |
2014年 | 427篇 |
2013年 | 485篇 |
2012年 | 542篇 |
2011年 | 502篇 |
2010年 | 301篇 |
2009年 | 255篇 |
2008年 | 324篇 |
2007年 | 268篇 |
2006年 | 258篇 |
2005年 | 206篇 |
2004年 | 175篇 |
2003年 | 183篇 |
2002年 | 153篇 |
2001年 | 130篇 |
2000年 | 128篇 |
1999年 | 106篇 |
1998年 | 64篇 |
1997年 | 39篇 |
1996年 | 45篇 |
1995年 | 40篇 |
1994年 | 42篇 |
1993年 | 30篇 |
1992年 | 43篇 |
1991年 | 57篇 |
1990年 | 41篇 |
1989年 | 46篇 |
1988年 | 30篇 |
1987年 | 37篇 |
1986年 | 34篇 |
1985年 | 33篇 |
1984年 | 40篇 |
1983年 | 38篇 |
1982年 | 25篇 |
1979年 | 26篇 |
1977年 | 18篇 |
1976年 | 23篇 |
1975年 | 19篇 |
1974年 | 26篇 |
1973年 | 29篇 |
1972年 | 20篇 |
1971年 | 19篇 |
排序方式: 共有7571条查询结果,搜索用时 15 毫秒
991.
992.
Zhen Zheng Long Chang Ivan Nekrashevich Paul Ruchhoeft Sakhrat Khizroev Dmitri Litvinov 《PloS one》2013,8(8)
We describe a low-energy glow-discharge process using reactive ion etching system that enables non-circular device patterns, such as squares or hexagons, to be formed from a precursor array of uniform circular openings in polymethyl methacrylate, PMMA, defined by electron beam lithography. This technique is of a particular interest for bit-patterned magnetic recording medium fabrication, where close packed square magnetic bits may improve its recording performance. The process and results of generating close packed square patterns by self-limiting low-energy glow-discharge are investigated. Dense magnetic arrays formed by electrochemical deposition of nickel over self-limiting formed molds are demonstrated. 相似文献
993.
994.
Fanconi syndrome is a complex of renal tubular dysfunctions defined by glycosuria without diabetes, aminoaciduria, phosphaturia, and renal tubular acidosis. It is often associated with hypokalemia, hypophosphatemia, and rickets or osteomalacia. Although it is usually found in the setting of other well-established non-renal diseases, Fanconi syndrome may present without identifiable etiology or association. Very infrequently a patient with idiopathic Fanconi syndrome will progress to chronic renal failure. This case report details the course of such a patient over the 20 years since his diagnosis and discusses the syndrome's genetic background, clinical features, putative pathophysiology, and therapeutic options, including transplantation. 相似文献
995.
996.
C. Vidal J.F. Menudet P. Cinquin J. Troccaz G. Morel J. Szewczyk J.J. Rambeaud J.A. Long P. Mozer 《IRBM》2010,31(2):122-126
This article presents work carried out as part of the robot sécurisé d’assistance à la chirurgie endoscopique (Rosace) project (funding ANR TecSan06), involving both academic and clinical partners along with an industrial partner in charge of technology integration. The main subject is a lightweight and compact robot for assistance in the endoscopic surgery field. The goal of the project has been to improve then transfer on a medical-grade product some technologies initially developed by the two academic partners. These technologies are: a first prototype of a robotic endoscope holder, an original method for visual servoing based on instrument tracking and some work done on comanipulation concept which consists in synergic interaction between robot and user. In accordance with the initial goals, major improvements have been obtained on these three aspects of the project. Robotic architecture improvement has contributed to enhance robot's versatility while robot command has been made more efficient and simple to use thanks to instrument tracking and comanipulation. After this 3-year project, initial prototype has turned into a commercially available product integrating (or that will integrate in a few months) these new technologies. 相似文献
997.
998.
Jie Chen Hongquan Peng Kun Zhang Long Xiao Zhimin Yuan Jianping Chen Zhiyu Wang Jingfeng Wang Hui Huang 《PloS one》2013,8(6)
The relations between dietary micronutrient, nutritional status and inflammation in hemodialysis patients are still unclear. A cross-sectional study was performed in hemodialysis population. 75 hemodialysis patients from South China participated in the dietary and nutritional assessment. Clinical and dietary data were collected. Nutritional status was assessed by Malnutrition-Inflammation Score (MIS) in addition to related anthropometric measurements. And according to the MIS score, the whole hemodialysis patients were divided into normal nutrition group and malnutrition group. The results showed that mid arm circumference (MAC) negatively correlated with MIS (r = −0.425; P = 0.002). The area under the ROC curve (AUC) for MAC was 0.737 (0.614–0.859). Comparing with the normal nutritional group, lower dietary selenium (Se), copper (Cu), iodine (I) and manganese (Mn) intake were observed among patients with malnutrition (P<0.05). While no significant differences of diverse vitamins were found. In conclusion, MAC was effective indicator for assessing nutritional and inflammatory status (P<0.05). The reduction of dietary Se, Cu, I and Mn intake level may be alarming markers for malnutrition and inflammatory status in hemodialysis patients. 相似文献
999.
1000.
Duoru Lin Jingjing Chen Zhuoling Lin Xiaoyan Li Xiaohang Wu Erping Long Lixia Luo Bo Zhang Hui Chen Wan Chen Li Zhang Haotian Lin Weirong Chen Yizhi Liu 《PloS one》2015,10(11)
A review of 6 years of hospitalization charts from Zhongshan Ophthalmic Center (ZOC) revealed that congenital cataracts (CC) accounted for 2.39% of all cataract in-patient cases and that the age at surgery was decreasing before the establishment of the Childhood Cataract Program of the Chinese Ministry of Health (CCPMOH) in December 2010. We aimed to investigate data from the 4 years (January 2011 to December 2014) following the establishment of the CCPMOH, compared, and combined with data from the previous study period (January 2005 to December 2010) to generate a 10-year overview of the hospital-based prevalence and treatment of CC. In the 4-year period after CCPMOH establishment, the prevalence of CC was 2.01% in all hospitalizations, and was 2.78% in all cataract in-patients. Most of the eligible CC in-patients (71%) lived in south China. The ratio of boys to girls was 1.42:1. Nearly 2/3 of the patients underwent cataract extraction with primary intraocular lens (IOL) implantation at a mean age of 78.40±51.45 months, and cataract extraction surgeries without IOL implantation were performed in the remaining 1/3 of patients at a mean age of 10.03±15.92 months. After CCPMOH establishment, an increased incidence of CC was revealed, and the CC in-patients were younger than the patients in the previous period. The 10-year overview (2421 CC in-patients from 206630 hospitalizations) revealed upward trends in both the number and the prevalence of CC and a further reduction in age at surgery. In conclusion, the data from 4-year period after CCPMOH establishment and the 10-year overview showed upward trends in the hospital-based prevalence of CC cases and a further reduction in age at surgery, likely reflecting the effects of the CCPMOH establishment and providing useful information for further CC studies and a valuable foundation for the prevention and treatment of this cause of childhood blindness. 相似文献