全文获取类型
收费全文 | 1637581篇 |
免费 | 133904篇 |
国内免费 | 27565篇 |
专业分类
耳鼻咽喉 | 21223篇 |
儿科学 | 49065篇 |
妇产科学 | 39078篇 |
基础医学 | 221348篇 |
口腔科学 | 39521篇 |
临床医学 | 162794篇 |
内科学 | 305593篇 |
皮肤病学 | 31998篇 |
神经病学 | 117738篇 |
特种医学 | 64567篇 |
外国民族医学 | 884篇 |
外科学 | 227996篇 |
综合类 | 96464篇 |
现状与发展 | 87篇 |
一般理论 | 407篇 |
预防医学 | 121906篇 |
眼科学 | 38362篇 |
药学 | 134410篇 |
431篇 | |
中国医学 | 26665篇 |
肿瘤学 | 98513篇 |
出版年
2022年 | 15026篇 |
2021年 | 25909篇 |
2020年 | 19162篇 |
2019年 | 20558篇 |
2018年 | 25006篇 |
2017年 | 21428篇 |
2016年 | 21395篇 |
2015年 | 28885篇 |
2014年 | 37783篇 |
2013年 | 44890篇 |
2012年 | 63810篇 |
2011年 | 69372篇 |
2010年 | 43933篇 |
2009年 | 39021篇 |
2008年 | 57492篇 |
2007年 | 59870篇 |
2006年 | 59211篇 |
2005年 | 57249篇 |
2004年 | 49900篇 |
2003年 | 48311篇 |
2002年 | 45480篇 |
2001年 | 71888篇 |
2000年 | 74268篇 |
1999年 | 64297篇 |
1998年 | 20238篇 |
1997年 | 18697篇 |
1996年 | 18060篇 |
1995年 | 17087篇 |
1994年 | 15828篇 |
1993年 | 13752篇 |
1992年 | 46753篇 |
1991年 | 45403篇 |
1990年 | 43886篇 |
1989年 | 41553篇 |
1988年 | 38078篇 |
1987年 | 37280篇 |
1986年 | 34480篇 |
1985年 | 32902篇 |
1984年 | 24476篇 |
1983年 | 20508篇 |
1982年 | 11840篇 |
1979年 | 21464篇 |
1978年 | 14876篇 |
1977年 | 12576篇 |
1976年 | 11722篇 |
1975年 | 12645篇 |
1974年 | 14696篇 |
1973年 | 14145篇 |
1972年 | 12973篇 |
1971年 | 11746篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
81.
82.
Zheng Xingming Ding Yanling Zhao Xiaowei Bai Yu Li Xiaofeng Zhao Kai 《Remote sensing letters.》2019,10(6):563-572
Vegetation water content (VWC) is the key input parameter for a soil moisture retrieval algorithm based on microwave remote sensing, and VWC uncertainty can limit the estimated accuracy of soil moisture. There has been little research on VWC algorithm development and validation in China, and the uncertainty of the VWC estimation method has not been well evaluated. Therefore, the aim of this study is to evaluate the uncertainty of the VWC estimation method used in the SMAP (Soil Moisture Active Passive) algorithm on three spatial scales (the point-scale, 30 m scale, and 1 km scale) for maize in northeast China. Results from three ground experimental datasets showed that the SMAP VWC estimation method was strongly biased with an average overestimation of 1.16 kg m?2,1.04 kg m?2, and 1.13 kg m?2 for the point-scale, 30 m scale, and 1 km scale respectively, and maximum bias occurred in the mid-stage of maize. Also, a new power relationship between NDVI (Normalized Difference Vegetation Index) and VWC was proposed for the 30 m scale based on Sentinel 2 NDVI and field VWC values from 2017 experiment, with respective R2 (coefficient of determination) and Root Mean Squared Error (RMSE) values of 0.80 and 0.67 kg m?2. The results confirmed that this power relationship was still suitable for VWC estimation at the 1 km scale, and it has smaller bias than the original SMAP VWC method. Future work will be carried out to evaluate the applicability of this VWC estimation method over a lager region. It is expected that it can improve the accuracy of soil moisture by providing high precision VWC input parameters. 相似文献
83.
84.
Amosova E. N. Shilova I. V. Zueva E. P. Rybalkina O. Yu. 《Pharmaceutical Chemistry Journal》2020,54(7):721-724
Pharmaceutical Chemistry Journal - Three extracts were produced from the above-ground part of the meadowsweet Filipendula ulmaria (L.) Maxim. using water, 40% ethanol, and 70% ethanol. Comparative... 相似文献
85.
86.
Yaqian Li Jingjing Yu Yun Kuang Chengkun Wu Liu Yang Qiulian Fang 《Current medical research and opinion》2020,36(9):1433-1439
Abstract
Objective
The sex, age, medical history, treatment, tobacco use, race risk (SAMe-TT2R2) Score; the sex, age, medical history, treatment, tobacco use, genotype combination (SAMe-TT2G2) Score; and the so-called modified SAMe-TT2R2 scores have been proposed to predict the anticoagulation quality for patients with non-valvular atrial fibrillation (NVAF). The data from a prospective controlled study is used to validate the SAMe-TT2R2 and SAMe-TT2G2 scores in Chinese NVAF patients treated with warfarin and to evaluate the association of factors with time in therapeutic range (TTR) to predict the quality of oral anticoagulation control. 相似文献87.
88.
89.
Koel Dutt P N Agarwal Rajdeep Singh Vikas Singh Tomar 《The Indian journal of surgery》2015,77(1):62-64
Haemophilia is a common cause of genetically inherited bleeding disorders. Pseudotumours occur in 1–2 % of persons with severe forms of haemophilia. These are a result of repeated haemorrhage into soft tissues, subperiosteum or a site of bone fracture with inadequate resorption of the extravasated blood. There are a number of therapeutic alternatives for this dangerous condition: surgical removal, percutaneous management, irradiation, embolization etc. In this case report, we describe the natural history, clinical course and successful surgical management of a patient with haemophilia who presented with a massive pseudotumour. We also briefly review the relevant literature on the various therapeutic modalities that have been implemented in the management of this rare complication. Though surgeons may be averse to operate on haemophiliacs, primary surgical management as done in our case may prove to be the definitive treatment option for such patients. 相似文献