全文获取类型
收费全文 | 210029篇 |
免费 | 20371篇 |
国内免费 | 12870篇 |
专业分类
耳鼻咽喉 | 1651篇 |
儿科学 | 3018篇 |
妇产科学 | 2214篇 |
基础医学 | 27061篇 |
口腔科学 | 3924篇 |
临床医学 | 25995篇 |
内科学 | 27287篇 |
皮肤病学 | 2345篇 |
神经病学 | 9166篇 |
特种医学 | 7305篇 |
外国民族医学 | 79篇 |
外科学 | 19807篇 |
综合类 | 38493篇 |
现状与发展 | 51篇 |
一般理论 | 15篇 |
预防医学 | 16368篇 |
眼科学 | 4957篇 |
药学 | 24142篇 |
209篇 | |
中国医学 | 13675篇 |
肿瘤学 | 15508篇 |
出版年
2024年 | 873篇 |
2023年 | 3316篇 |
2022年 | 8584篇 |
2021年 | 10786篇 |
2020年 | 8188篇 |
2019年 | 6664篇 |
2018年 | 6865篇 |
2017年 | 6799篇 |
2016年 | 6176篇 |
2015年 | 9325篇 |
2014年 | 11596篇 |
2013年 | 11837篇 |
2012年 | 16496篇 |
2011年 | 17725篇 |
2010年 | 12927篇 |
2009年 | 10596篇 |
2008年 | 12348篇 |
2007年 | 12013篇 |
2006年 | 10882篇 |
2005年 | 9648篇 |
2004年 | 7214篇 |
2003年 | 6756篇 |
2002年 | 5625篇 |
2001年 | 4503篇 |
2000年 | 3827篇 |
1999年 | 3233篇 |
1998年 | 1978篇 |
1997年 | 2099篇 |
1996年 | 1497篇 |
1995年 | 1396篇 |
1994年 | 1262篇 |
1993年 | 854篇 |
1992年 | 1057篇 |
1991年 | 944篇 |
1990年 | 864篇 |
1989年 | 765篇 |
1988年 | 684篇 |
1987年 | 600篇 |
1986年 | 537篇 |
1985年 | 436篇 |
1984年 | 374篇 |
1983年 | 306篇 |
1982年 | 269篇 |
1981年 | 232篇 |
1980年 | 199篇 |
1979年 | 201篇 |
1978年 | 192篇 |
1977年 | 211篇 |
1976年 | 191篇 |
1974年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Xinliang Fu Zhanpeng Hou Wenjun Liu Nan Cao Yu Liang Bingxin Li Danli Jiang Wanyan Li Danning Xu Yunbo Tian Yunmao Huang 《Viruses》2022,14(6)
A novel gout disease, characterized by visceral urate deposition with high-mortality, with outbreaks in goslings in China since 2016 was caused by a novel goose astrovirus (GoAstV) and resulted in serious economic loss. However, the epidemiology and variation of the GoAstV in goslings in southern China and its evolutionary history as well as the classification of the GoAstV are unclear. In the present study, systematic molecular epidemiology, and phylogenetic analyses of the GoAstV were conducted to address these issues. Our results showed that the GoAstV is widespread in goslings in southern China, and the genomes of six GoAstV strains were obtained. Two amino acid mutations (Y36H and E456D) were identified in capsid proteins in this study, which is the dominant antigen for the GoAstV. In addition, the GoAstV could be divided into two distinct clades, GoAstV-1 and GoAstV-2, and GoAstV-2 is responsible for gout outbreaks in goslings and could be classified into Avastrovirus 3 (AAstV-3), while GoAstV-1 belongs to Avastrovirus 1 (AAstV-1). Moreover, the emergence of GoAstV-2 in geese was estimated to have occurred in January 2010, approximately 12 years ago, while GoAstV-1 emerged earlier than GoAstV-2 and was estimated to have emerged in April 1985 based on Bayesian analysis. The mean evolutionary rate for the GoAstV was also calculated to be approximately 1.42 × 10−3 nucleotide substitutions per site per year. In conclusion, this study provides insight into the epidemiology of the GoAstV in goslings in southern China and is helpful for understanding the origin and evolutionary history as well as the classification of the GoAstV in geese. 相似文献
992.
The Global Leadership Initiative on Malnutrition (GLIM) has achieved a consensus for the diagnosis of malnutrition in recent years. This study aims to determine the prognostic effect of the GLIM after cardiac surgery. A total of 603 patients in the training cohort and 258 patients in the validation cohort were enrolled in this study. Perioperative characteristics and follow-up data were collected. A nomogram based on independent prognostic predictors was developed for survival prediction. In total, 114 (18.9%) and 48 (18.6%) patients were defined as being malnourished according to the GLIM criteria in the two cohorts, respectively. Multivariate regression analysis showed that GLIM-defined malnutrition was an independent risk factor of total complication (OR 1.661, 95% CI: 1.063–2.594) and overall survival (HR 2.339, 95% CI: 1.504–3.637). The c-index was 0.72 (95% CI: 0.66–0.79) and AUC were 0.800, 0.798, and 0.780 for 1-, 2-, and 3-year survival prediction, respectively. The calibration curves of the nomogram fit well. In conclusion, GLIM criteria can efficiently identify malnutrition and has a prognostic effect on clinical outcomes after cardiac surgery. GLIM-based nomogram has favorable performance in survival prediction. 相似文献
993.
Shuting Si Zhicheng Peng Haoyue Cheng Yan Zhuang Peihan Chi Xialidan Alifu Haibo Zhou Minjia Mo Yunxian Yu 《Nutrients》2022,14(12)
The association between vitamin D and hemoglobin has been suggested. Vitamin D can affect erythropoiesis by the induction of erythroid progenitor cell proliferation and enhance iron absorption by regulating the iron-hepcidin-ferroportin axis in monocytes. However, this relationship in pregnant women is scarce. The purpose of this study was to investigate the association between plasma vitamin D levels with hemoglobin concentration in pregnant women considering each trimester and iron supplementation. The data were obtained from Zhoushan Pregnant Women Cohort, collected from 2011 to 2018. Plasma 25(OH)D was measured in each trimester using liquid chromatography–tandem mass spectrometry. Generalized estimating equations and multiple linear regressions were performed. Finally, 2962 pregnant women and 4419 observations in the first trimester were included in this study. Plasma 25(OH)D in first trimester (T1) (β = 0.06, p = 0.0177), second trimester (T2) (β = 0.15, p < 0.0001), and third trimester (T3) (β = 0.12, p = 0.0006) were positively associated with Hb. Association between plasma 25(OH)D levels in T1 and Hb concentration was positively associated with gestational age (β = 0.005, p = 0.0421). Pregnant women with VD deficiency in T1 (OR = 1.42, 95% CI: 1.07–1.88) or T2 (OR = 1.94, 95% CI: 1.30–2.89) presented an increased risk of anemia, compared with women without VD deficiency. Moreover, the significant relationship between VD and Hb was only observed among women with iron supplementation during pregnancy. Plasma 25(OH)D levels in each trimester were positively associated with Hb concentration. Iron supplementation might be an important factor affecting the relationship between VD and Hb. 相似文献
994.
Enyue Fang Xiaohui Liu Miao Li Jingjing Liu Zelun Zhang Xinyu Liu Xingxing Li Wenjuan Li Qinhua Peng Yongxin Yu Yuhua Li 《Viruses》2022,14(6)
Since the first isolation in 1943, the dengue virus (DENV) has spread throughout the world, but effective antiviral drugs or vaccines are still not available. To provide a more stable reporter DENV for vaccine development and antiviral drug screening, we constructed a reporter DENV containing the NanoLuc reporter gene, which was inserted into the 5′ untranslated region and capsid junction region, enabling rapid virus rescue by in vitro ligation. In addition, we established a live imaging mouse model and found that the reporter virus maintained the neurovirulence of prototype DENV before engineering. DENV-4 exhibited dramatically increased neurovirulence following a glycosylation site-defective mutation in the envelope protein. Significant mice mortality with neurological onset symptoms was observed after intracranial infection of wild-type (WT) mice, thus providing a visualization tool for DENV virulence assessment. Using this model, DENV was detected in the intestinal tissues of WT mice after infection, suggesting that intestinal lymphoid tissues play an essential role in DENV pathogenesis. 相似文献
995.
Nano-scale crystal defects extremely affect the security and reliability of the explosive charges of weapons. In order to understand the evolution of nano-scale defects of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20) explosive crystals under thermal treatments, the specific surface, volume fraction and size distribution of the nano-scale defects were studied by using Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS) during the temperature range from 30 °C to 200 °C. The results showed that the number and size of the pores in CL-20 powder did not change significantly during the heating process before phase transformation (30–160 °C). At 170 °C, CL-20 began to convert from ε- to γ- phase, and the specific surface and volume fraction of the nano-scale defects increased significantly. Further investigation of the pore size distribution showed that the number of pores with a small size (radius 9–21 nm) changed particularly significantly, resulting from the cracking of the CL-20 crystal powder during phase transition. At 200 °C, the phase transition was completed and γ-CL-20 was created, and the small-sized pores gradually grew into medium-sized (radius 21–52 nm) pores over time when the temperature was fixed at 200 °C. 相似文献
996.
Pragney Deme Leah H. Rubin Danyang Yu Yanxun Xu Gertrude Nakigozi Noeline Nakasujja Aggrey Anok Alice Kisakye Thomas C. Quinn Steven J. Reynolds Richard Mayanja James Batte Maria J. Wawer Ned C. Sacktor Deanna Saylor Norman J. Haughey 《Viruses》2022,14(6)
Background: HIV infection results in immunometabolic reprogramming. While we are beginning to understand how this metabolic reprogramming regulates the immune response to HIV infection, we do not currently understand the impact of ART on immunometabolism in people with HIV (PWH). Methods: Serum obtained from HIV-infected (n = 278) and geographically matched HIV seronegative control subjects (n = 300) from Rakai Uganda were used in this study. Serum was obtained before and ~2 years following the initiation of ART from HIV-infected individuals. We conducted metabolomics profiling of the serum and focused our analysis on metabolic substrates and pathways assocaited with immunometabolism. Results: HIV infection was associated with metabolic adaptations that implicated hyperactive glycolysis, enhanced formation of lactate, increased activity of the pentose phosphate pathway (PPP), decreased β-oxidation of long-chain fatty acids, increased utilization of medium-chain fatty acids, and enhanced amino acid catabolism. Following ART, serum levels of ketone bodies, carnitine, and amino acid metabolism were normalized, however glycolysis, PPP, lactate production, and β-oxidation of long-chain fatty acids remained abnormal. Conclusion: Our findings suggest that HIV infection is associated with an increased immunometabolic demand that is satisfied through the utilization of alternative energetic substrates, including fatty acids and amino acids. ART alone was insufficient to completely restore this metabolic reprogramming to HIV infection, suggesting that a sustained impairment of immunometabolism may contribute to chronic immune activation and comorbid conditions in virally suppressed PWH. 相似文献
997.
This study aimed to explore the wear characteristics and evolution mechanisms of large-scale wind power gears under the impact load of particles of the three-body abrasive Al2O3 (0.2 mg/mL) from four aspects: oil analysis, vibration analysis, amount of gear wear, and tooth-surface-wear profile analysis. A magnetic powder brake was used to simulate the actual working conditions. Combined with the abrasive particle monitoring and the morphology analysis of the tooth-surface-wear scar, by setting quantitative hard particles in the lubricating oil, the gears are mainly operated in the abrasive wear state, and wear monitoring and wear degree analysis are carried out for the whole life cycle of the gears. Oil samples were observed and qualitatively analyzed using a particle counter, a single ferrograph, a metallographic microscope, and a scanning electron microscope. The experiments demonstrate that the initial hard particles have a greater impact in the early wear stage of the gears (<20 h), and abrasive particle concentration increases by 30%. This means that Al2O3 particles accelerate the gear wear during the running-in period. The loading method of the impact load on the oblique gear exacerbates the abrasion particle wear and expands the stress concentration, which reduces the surface of large milling particles on the surface, and reduces the width of the tooth (the part above the pitch line is severely worn), which causes the gear to break into failure. The research provides help for analyzing the mechanism of abrasive wear of gears and predicting wear life. 相似文献
998.
目的:了解小城镇及农村残疾人的抑郁水平及其相关因素,为其居家照顾者减轻残疾人抑郁提供理论依据。方法:采用抑郁自评量表(SDS)、Barthel氏ADL指数量表、Procidana与Heller家庭支持量表及自行设计的一般资料问卷,对居住在小城镇及农村的63例残疾人进行问卷调查。结果:残疾人有抑郁症状的比例高达69.8%,残疾人抑郁水平与日常生活活动能力(ADL)及残疾人对其家庭照顾者照顾满意度呈负相关,有非常显著的统计学意义(P=0.000)。结论小城镇及农村残疾人的抑郁症状普遍较严重,社会应给予更多的关注,应大力发展社区护理,为有需要的残疾人上门服务,并加强对残疾人家庭照顾者的培训指导,以提高残疾人生活质量与心理健康水平。 相似文献
999.
Dedifferentiated liposarcoma (DDLPS) is a rare subtype of liposarcoma with a poor prognosis. This current case report describes a rectal DDLPS in a 68-year-old Chinese male that presented with lower abdominal pain and weight loss. Computed tomography and magnetic resonance imaging were undertaken to evaluate the tumour. The patient underwent radical resection of the rectal tumour, sigmoid colostomy and partial ureterectomy. The tumour was positive for mouse double minute 2 by immunohistochemistry. The patient healed well but refused chemotherapy postoperatively for economic reasons. The tumour recurred and metastasized 4 weeks after the operation. After relevant treatment, the patient''s condition deteriorated and he died of shock, metabolic acidosis, hyperlactataemia and acute renal failure. The case report also reviews the literature in terms of the clinical diagnosis, treatment and pathological characteristics of rectal DDLPS with the aim of improving the level of diagnosis and treatment. 相似文献
1000.