全文获取类型
收费全文 | 25452篇 |
免费 | 2584篇 |
国内免费 | 1879篇 |
专业分类
耳鼻咽喉 | 193篇 |
儿科学 | 382篇 |
妇产科学 | 276篇 |
基础医学 | 3066篇 |
口腔科学 | 447篇 |
临床医学 | 3532篇 |
内科学 | 3903篇 |
皮肤病学 | 238篇 |
神经病学 | 1410篇 |
特种医学 | 965篇 |
外国民族医学 | 18篇 |
外科学 | 2432篇 |
综合类 | 4307篇 |
现状与发展 | 8篇 |
一般理论 | 3篇 |
预防医学 | 1784篇 |
眼科学 | 605篇 |
药学 | 2624篇 |
30篇 | |
中国医学 | 1528篇 |
肿瘤学 | 2164篇 |
出版年
2024年 | 100篇 |
2023年 | 447篇 |
2022年 | 1124篇 |
2021年 | 1391篇 |
2020年 | 1028篇 |
2019年 | 920篇 |
2018年 | 1005篇 |
2017年 | 896篇 |
2016年 | 809篇 |
2015年 | 1214篇 |
2014年 | 1536篇 |
2013年 | 1335篇 |
2012年 | 1854篇 |
2011年 | 2097篇 |
2010年 | 1310篇 |
2009年 | 1016篇 |
2008年 | 1326篇 |
2007年 | 1273篇 |
2006年 | 1276篇 |
2005年 | 1217篇 |
2004年 | 843篇 |
2003年 | 784篇 |
2002年 | 684篇 |
2001年 | 582篇 |
2000年 | 621篇 |
1999年 | 582篇 |
1998年 | 311篇 |
1997年 | 349篇 |
1996年 | 278篇 |
1995年 | 263篇 |
1994年 | 235篇 |
1993年 | 165篇 |
1992年 | 167篇 |
1991年 | 128篇 |
1990年 | 147篇 |
1989年 | 102篇 |
1988年 | 90篇 |
1987年 | 82篇 |
1986年 | 53篇 |
1985年 | 56篇 |
1984年 | 49篇 |
1983年 | 37篇 |
1982年 | 19篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1968年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
4.
Increased arterial stiffness in young normotensive patients with Turner syndrome: associations with vascular biomarkers 下载免费PDF全文
5.
Yuan-Zhang Tang Bai-Shan Wu Li-Qiang Yang Jian-Ning Yue Liang-Liang He Na Li Jia-Xiang Ni 《Medicine》2015,94(45)
To evaluate the efficacy of computed tomography (CT) guided single radiofrequency thermocoagualtion (RFT) in 1137 patients with idiopathic trigeminal neuralgia after a follow-up period of 11 years, specially focused on duration of pain relief in different branches of trigeminal nerve, side effect, and complications.Retrospective study of patients with idiopathic trigeminal neuralgia treated with a single CT guided RFT procedure between January 2002 and December 2013.The mean follow-up time was 46.14 ± 30.91 months. Immediate postprocedure pain relief was 98.4%. V2 division obtained the best pain relief rate: 91%, 89%, 80%, 72%, 60%, and 54% at 1, 3, 5, 7, 9, and 11 years, respectively. No statistical difference pairwise comparison was in other groups. The complications included masseter muscle weakness, corneitis, diplopia, ptosis, hearing loss, limited mouth opening, and low pressure headache. Masticatory weakness mostly occurred in patients with V3 branch involvement, while Corneitis and Diplopia all in patients with V1 branch involvement. No mortalities observed during or after RFT.All different branches division of trigeminal neuralgia achieved comparable satisfactory curative effect; V2 obtained the best excellent pain relief, after RFT procedure. Facial numbness is inevitable after RFT, which patients who have pain in all 3 trigeminal divisions and patients who desire no facial numbness should be cautious. Masticatory weakness is mainly related with V3 injured, while Corneitis and Diplopia in patients with V1 injured by RFT. 相似文献
6.
7.
Sequential Therapy Based on Evolvement of Patterns: A New Model for Treatment of Alzheimer’s Disease
In order to solve the problem of long-term (>9 months) efficacy in the treatment of Alzheimer''s disease (AD) by conventional therapy (CT), a staged and multiply-targeted sequential therapy based on the evolvement of patterns (STEP) was developed. Its main innovations include: (1) the time order of evolution of patterns defined by Chinese medicine (CM) in AD was found, that is, "the orderly pattern evolution starting from Shen (Kidney) deficiency, progressing to phlegm, stasis and fire, and worsening to severe toxin as well as functional collapse"; (2) the cascade hypothesis of Shen deficiency in AD and its sequential therapy based on Shen-reinforcing was proposed, that is, "reinforcing Shen in the early stage and throughout the whole process, resolving phlegm, activating blood and purging fire in the middle stage, detoxifying and replenishing vitality to stop the collapse in the advanced stage", and through meta-analysis, clinical drug use was optimized, thus the leap from "inferential selection" to "evidence-based selection" was realized; (3) the STEP regimen combined with CT maintained cognitive and behavioral stability in AD patients for at least 12 months, with cognitive enhancement and behavioral synergy after 9 months, and cognitive benefit was superior to CT at 9, 12, 15, 18, 21, and 24 months, respectively. The 2-year cognitive improvement rate was increased by 25.64% (P=0.020) and the cognitive deterioration rate was decreased by 48.71% (P=0.000). Among them, the cognitive and functional benefits of Shen-reinforcing therapy for very early AD (350 cases) for 1 year were better than the placebo (P<0.001), and the dementia conversion rate was reduced by 8.85% (P=0.002). The behavioral symptomatic relief of patients with vascular dementia received fire-purging therapy (540 cases) was superior to those received CT (P=0.016). These data suggested that the STEP regimen has synergistic effects on CTs at least in terms of cognitive benefit, and the earlier the use, the greater the benefit will have. Therefore, the STEP regimen should be considered as one of the clinical options, particularly for the dearth of effective pharmaceutical or immunological interventions that are currently available for AD. 相似文献
8.
Limb shortening is a problem associated with surgery for osteosarcoma of the lower extremity in adolescents, as the tumors frequently occur near the epiphysis. Herein we report the use of a less invasive stabilization system (LISS) and an intermittent fixation method to preserve the growth function of epiphysis in an 11-year-old patient with an osteosarcoma of the distal femur.The 11-year-old male presented with left knee enlargement and pain for 2 weeks, and magnetic resonance imaging (MRI) and biopsy were consistent with osteosarcoma of the left distal femur. After preoperative chemotherapy, en bloc tumor resection was performed with margins based on MRI findings preserving the epiphyseal growth plate, the tumor cavity was filled with inactivated bone and bone cement, and a LISS was used to stabilize the femur. Aggressive postoperative chemotherapy was given. Approximately 105 weeks after surgery radiography showed that the distal end of the plate had moved superior to the epiphysis along with bone growth. Locking screws were placed in the distal part of the LISS plate to stabilize the re-implanted bone, and external fixation was not needed.The patient was able to walk with the crutches 1 week postoperatively, and bear weight on the extremity 6 weeks postoperatively. At 6 years after surgery, the patient''s height had increased 52 cm, shortening of the affected limb was only 1 cm, and the circumference of the affected limb was 2 cm smaller than that of the contralateral limb. There was no significant discomfort in the affected limb, and there was no gait abnormality. The patient could jump and run, and could participate in sports including basketball and badminton to the same degree as his peers.In summary, the novel method of bone reconstruction and fixation provided good results in a child with an osteosarcoma of the distal femur. This fixation method preserves the osteogenic function of the epiphysis and restored bone integrity simultaneously, and provides good functional recovery. 相似文献
9.
10.
骨髓移植术后急性肠道移植物抗宿主病内镜及病理学诊断研究 总被引:1,自引:0,他引:1
目的评价内镜和病理学诊断在急性肠道移植物抗宿主病(GVHD)中的作用。方法回顾性总结和分析2001—2005年北京大学人民医院血液病学研究所临床已确诊的23例急性肠道GVHD患者的内镜及病理学资料。结果内镜下表现可分为:黏膜大致正常、血管纹理模糊或消失、弥漫性黏膜充血、水肿和脆性增加,重者出现糜烂、溃疡,甚至黏膜脱落或出血;病理学表现提示:隐窝上皮细胞凋亡、缺失,隐窝结构破坏,上皮和黏膜固有层不同程度的淋巴细胞浸润。结论内镜和病理学检查可以用于急性肠道GVHD的诊断,尤其是内镜在急性肠道GVHD的早期诊断方面具有重要作用,同时结合病理学检查最终确立诊断。 相似文献