全文获取类型
收费全文 | 79665篇 |
免费 | 7548篇 |
国内免费 | 5310篇 |
学科分类
医药卫生 | 92523篇 |
出版年
2024年 | 90篇 |
2023年 | 1091篇 |
2022年 | 1621篇 |
2021年 | 3504篇 |
2020年 | 2981篇 |
2019年 | 2881篇 |
2018年 | 3066篇 |
2017年 | 2539篇 |
2016年 | 2643篇 |
2015年 | 3800篇 |
2014年 | 4721篇 |
2013年 | 4170篇 |
2012年 | 6179篇 |
2011年 | 6615篇 |
2010年 | 4097篇 |
2009年 | 3107篇 |
2008年 | 4293篇 |
2007年 | 4191篇 |
2006年 | 4257篇 |
2005年 | 4089篇 |
2004年 | 2780篇 |
2003年 | 2546篇 |
2002年 | 2077篇 |
2001年 | 1783篇 |
2000年 | 1776篇 |
1999年 | 2047篇 |
1998年 | 1285篇 |
1997年 | 1274篇 |
1996年 | 963篇 |
1995年 | 925篇 |
1994年 | 786篇 |
1993年 | 499篇 |
1992年 | 601篇 |
1991年 | 503篇 |
1990年 | 481篇 |
1989年 | 424篇 |
1988年 | 389篇 |
1987年 | 304篇 |
1986年 | 257篇 |
1985年 | 224篇 |
1984年 | 134篇 |
1983年 | 91篇 |
1982年 | 52篇 |
1981年 | 57篇 |
1980年 | 38篇 |
1979年 | 65篇 |
1978年 | 28篇 |
1977年 | 21篇 |
1976年 | 20篇 |
1974年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Monitoring vegetation dynamics using the universal normalized vegetation index (UNVI): An optimized vegetation index-VIUPD 总被引:2,自引:0,他引:2
Lifu Zhang Na Qiao Muhammad Hasan Ali Baig Xin Lv Xuejian Sun 《Remote sensing letters.》2019,10(7):629-638
This paper propose a universal normalized vegetation index (UNVI), which is an improved vegetation index (VI) based on the universal pattern decomposition method (UPDM), termed VIUPD. We also derive new matrices to facilitate convenient calculation of the UNVI based on data from the MODIS and Landsat-TM, ETM, OLI satellite sensors. We compared the performance of the UNVI to the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and modified soil adjusted vegetation index 2 (MSAVI2) to estimate the vegetation dynamics (chlorophyll content and leaf area index [LAI]). The results show that the UNVI was more sensitive to vegetation dynamics than the NDVI, EVI and MSAVI2. The UNVI has a higher LAI saturation point than the other three indices. The UNVI can be used to monitor global changes in above ground biomass (AGB) and gross primary production (GPP) with respect to a wide range of vegetation dynamics. 相似文献
93.
Lesley A. Inker Morgan E. Grams Andrew S. Levey Josef Coresh Massimo Cirillo John F. Collins Ron T. Gansevoort Orlando M. Gutierrez Takayuki Hamano Gunnar H. Heine Shizukiyo Ishikawa Sun Ha Jee Florian Kronenberg Martin J. Landray Katsuyuki Miura Girish N. Nadkarni Carmen A. Peralta Dietrich Rothenbacher Mark Woodward 《American journal of kidney diseases》2019,73(2):206-217
94.
自2009年国家个人剂量登记系统应用以来,我国放射卫生信息化建设已走过10个年头,建立了全国放射卫生信息平台,涵盖个人剂量、职业性放射性疾病与职业健康、医用辐射防护、食品放射性核素监测、职业性放射性疾病报告5个系统,截至2018年,采集监测数据800余万条,平台授权用户1 400余名。本文就10年来我国放射卫生信息化建设的现状进行分析与总结,探讨放射卫生信息化发展的重点和难点,提出建议等,以期推进放射卫生信息化建设工作,更好地为职业性放射性疾病的预防与控制服务,助力"健康中国"建设。 相似文献
95.
96.
Xue Yao Yan Zhang Jian Hao Hui-Quan Duan Chen-Xi Zhao Chao Sun Bo Li Bao-You Fan Xu Wang Wen-Xiang Li Xuan-Hao Fu Yong Hu Chang Liu Xiao-Hong Kong Shi-Qing Feng 《中国神经再生研究》2019,(3)
Ferroptosis is an iron-dependent novel cell death pathway. Deferoxamine, a ferroptosis inhibitor, has been reported to promote spinal cord injury repair. It has yet to be clarified whether ferroptosis inhibition represents the mechanism of action of Deferoxamine on spinal cord injury recovery. A rat model of Deferoxamine at thoracic 10 segment was established using a modified Allen's method. Ninety 8-week-old female Wistar rats were used. Rats in the Deferoxamine group were intraperitoneally injected with 100 mg/kg Deferoxamine 30 minutes before injury. Simultaneously, the Sham and Deferoxamine groups served as controls. Drug administration was conducted for 7 consecutive days. The results were as follows:(1) Electron microscopy revealed shrunken mitochondria in the spinal cord injury group.(2) The Basso, Beattie and Bresnahan locomotor rating score showed that recovery of the hindlimb was remarkably better in the Deferoxamine group than in the spinal cord injury group.(3) The iron concentration was lower in the Deferoxamine group than in the spinal cord injury group after injury.(4) Western blot assay revealed that, compared with the spinal cord injury group, GPX4, xCT, and glutathione expression was markedly increased in the Deferoxamine group.(5) Real-time polymerase chain reaction revealed that, compared with the Deferoxamine group, mRNA levels of ferroptosis-related genes Acyl-CoA synthetase family member 2(ACSF2) and iron-responsive element-binding protein 2(IREB2) were up-regulated in the Deferoxamine group.(6) Deferoxamine increased survival of neurons and inhibited gliosis. These findings confirm that Deferoxamine can repair spinal cord injury by inhibiting ferroptosis. Targeting ferroptosis is therefore a promising therapeutic approach for spinal cord injury. 相似文献
97.
98.
99.
目的了解慢性病患者健康信息搜寻行为现况,为健康教育方案的制订提供参考。方法以方便抽样方法抽取慢性病住院患者313例,采用健康信息搜寻行为问卷对患者进行调查。结果慢性病住院患者信息需求维度得分(4.30±0.67)分,对健康信息搜寻行为的态度维度得分(3.94±0.85)分,获取健康信息的障碍维度得分(3.11±1.04)分,健康信息来源维度得分(3.10±0.96)分。结论慢性病患者对健康信息搜寻行为的态度处于中等偏上水平,对健康信息的需求较高。需开展以患者健康信息需求为导向、由医护人员和患者合作参与的多形式健康教育,以提高和改善慢性病患者的疾病管理能力与信心。 相似文献
100.