全文获取类型
收费全文 | 81790篇 |
免费 | 6886篇 |
国内免费 | 3662篇 |
专业分类
耳鼻咽喉 | 1053篇 |
儿科学 | 989篇 |
妇产科学 | 1040篇 |
基础医学 | 11494篇 |
口腔科学 | 1400篇 |
临床医学 | 9071篇 |
内科学 | 14044篇 |
皮肤病学 | 1996篇 |
神经病学 | 5099篇 |
特种医学 | 4130篇 |
外国民族医学 | 37篇 |
外科学 | 9293篇 |
综合类 | 7880篇 |
现状与发展 | 8篇 |
一般理论 | 8篇 |
预防医学 | 4487篇 |
眼科学 | 2290篇 |
药学 | 7928篇 |
43篇 | |
中国医学 | 3061篇 |
肿瘤学 | 6987篇 |
出版年
2024年 | 161篇 |
2023年 | 960篇 |
2022年 | 2822篇 |
2021年 | 3910篇 |
2020年 | 2483篇 |
2019年 | 2510篇 |
2018年 | 2754篇 |
2017年 | 2384篇 |
2016年 | 2881篇 |
2015年 | 4090篇 |
2014年 | 4973篇 |
2013年 | 4774篇 |
2012年 | 7279篇 |
2011年 | 7206篇 |
2010年 | 4597篇 |
2009年 | 3748篇 |
2008年 | 4850篇 |
2007年 | 4532篇 |
2006年 | 4127篇 |
2005年 | 3745篇 |
2004年 | 2793篇 |
2003年 | 2530篇 |
2002年 | 2213篇 |
2001年 | 1468篇 |
2000年 | 1473篇 |
1999年 | 1353篇 |
1998年 | 763篇 |
1997年 | 791篇 |
1996年 | 605篇 |
1995年 | 502篇 |
1994年 | 402篇 |
1993年 | 295篇 |
1992年 | 380篇 |
1991年 | 322篇 |
1990年 | 255篇 |
1989年 | 240篇 |
1988年 | 208篇 |
1987年 | 177篇 |
1986年 | 133篇 |
1985年 | 120篇 |
1984年 | 72篇 |
1983年 | 75篇 |
1982年 | 32篇 |
1981年 | 35篇 |
1980年 | 31篇 |
1979年 | 52篇 |
1978年 | 35篇 |
1977年 | 31篇 |
1973年 | 23篇 |
1971年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
In this paper, we introduce a new type of troubled-cell indicator to improve
hybrid weighted essentially non-oscillatory (WENO) schemes for solving the hyperbolic conservation laws. The hybrid WENO schemes selectively adopt the high-order
linear upwind scheme or the WENO scheme to avoid the local characteristic decompositions and calculations of the nonlinear weights in smooth regions. Therefore,
they can reduce computational cost while maintaining non-oscillatory properties in
non-smooth regions. Reliable troubled-cell indicators are essential for efficient hybrid
WENO methods. Most of troubled-cell indicators require proper parameters to detect
discontinuities precisely, but it is very difficult to determine the parameters automatically. We develop a new troubled-cell indicator derived from the mean value theorem
that does not require any variable parameters. Additionally, we investigate the characteristics of indicator variable; one of the conserved properties or the entropy is considered as indicator variable. Detailed numerical tests for 1D and 2D Euler equations are
conducted to demonstrate the performance of the proposed indicator. The results with
the proposed troubled-cell indicator are in good agreement with pure WENO schemes.
Also the new indicator has advantages in the computational cost compared with the
other indicators. 相似文献
12.
Sophocarpine attenuates toll‐like receptor 4 in steatotic hepatocytes to suppress pro‐inflammatory cytokines synthesis 下载免费PDF全文
13.
14.
Kun‐Yong Sung Seungkoo Lee Yeonjin Jeong Sang‐Yeul Lee 《The Australasian journal of dermatology》2021,62(1):60-63
A classic pilomatricoma, which usually presents with an asymptomatic, solitary, firm, subcutaneous nodule in the head, neck, or extremities of the paediatric population, is easily diagnosed based on its characteristic clinical and histopathological features. However, its variants often pose particular diagnostic challenges to clinicians due to their rarity and diverse clinicopathological features. We present a new pseudocystic variant, manifesting as solid lesions floating in a fluid‐filled sac. 相似文献
15.
16.
【目的】探讨中药淫羊藿、巴戟天提取物(中药注射液喘可治的组成)对恒河猴单核衍生的巨噬细胞在未极化(M0)、M1极化条件下基因表达的影响,分析其可能的免疫调节的作用机制。【方法】采用密度梯度离心法分离中国恒河猴外周血单个核细胞(PBMCs),采用贴壁法纯化出单核细胞,并以粒细胞巨噬细胞集落刺激因子(GM-CSF)刺激5 d以使单核细胞分化成巨噬细胞;然后不加入极化因子(M0)或以干扰素γ(IFN-γ,继续培养2 d)诱导巨噬细胞极化为M1表型,同时分别加入淫羊藿、巴戟天提取物进行干预;然后提取m RNA并逆转录后,采用实时荧光定量PCR检测CCR5、CD4、CTLA-4、Fox P3、IDO、IL-10、TGF-β等基因表达量。【结果】与空白对照组比较,加入巴戟天提取物培养的M0巨噬细胞基因表达上调不明显;经淫羊藿提取物培养的M0巨噬细胞,CCR5基因表达量上调4.21倍,TGF-β上调7.66倍,Fox P3、IL-10轻度上调,而CD4、CTLA-4、IDO等基因表达改变倍数无明显变化。经巴戟天提取物刺激的M1型巨噬细胞,CTLA-4基因表达量上调3.22倍,Fox P3上调3.69倍,CCR5、CD4、IL-10、IDO基因改变倍数均无明显变化,TGF-β未测出;而由淫羊藿提取物刺激的M1型巨噬细胞,IL-10的表达量上调11.83倍,Fox P3上调4.55倍,IDO、CCR5、CD4、CTLA-4基因改变倍数无明显变化,TGF-β未测出。【结论】巴戟天和淫羊藿提取物培养能够上调M1型巨噬细胞IL-10、Fox P3、CTLA-4等抑炎基因表达,淫羊藿提取物能够上调M0巨噬细胞CCR5和TGF-β等基因表达,促进病原体清除和组织修复,从而发挥多效免疫调节作用。 相似文献
17.
To evaluate the anthropometric indexes in subjects with varicocele compared to controls and the incidence of varicocele in different body mass index (BMI) groups for the purpose of exploring the association between varicocele and anthropometric indexes. A comprehensive literature search was conducted by using PubMed, MEDLINE, EMBASE databases and Cochrane Library up to February 2019. A systematic review and meta‐analysis was conducted by STATA, and Newcastle–Ottawa Scale was utilised for assessing risk of bias. Ultimately, 13 articles containing seven case–control studies and six cross‐sectional studies with 1,385,630 subjects were involved in our study. Pooled results demonstrated that varicocele patients had a lower BMI (WMD = ?0.77, 95% CI = ?1.03 to ?0.51) and a higher height than nonvaricocele participants, especially in grade 3 varicocele patients. Subgroup analyses showed that normal BMI individuals had a higher risk of varicocele than obese or overweight individuals and a lower risk than underweight individuals. In conclusion, this study indicates that varicocele patients have a lower BMI and a higher height than nonvaricocele participants. Moreover, men with excess bodyweight have a lower incidence of varicocele compared to normal weight or underweight people. That is to say, high BMI and adiposity protect against varicocele and high BMI is associated with a decreased risk of varicocele. 相似文献
18.
19.
20.
Qianlai Luo Jonathan N. Hofmann Ruth M. Pfeiffer Cari M. Kitahara Minkyo Song Meredith S. Shiels 《International journal of cancer. Journal international du cancer》2023,153(1):64-72
In the United States, renal cell carcinoma (RCC) incidence and the prevalence of obesity, an established risk factor for RCC, have been increasing for several decades. RCC is more common among older individuals. We sought to quantify the contribution of excess adiposity to the rising incidence of RCC among individuals 60 years or older. National Institutes of Health-American Association of Retired Persons Diet and Health Study data (n = 453 859 participants, enrolled in 1995-1996, age at enrollment 50-71 years) were used to estimate multivariable-adjusted hazard ratios (HRs) for RCC across body mass index categories and HRs associated with smoking. Population attributable fractions (PAFs) were calculated using estimated HRs and annual overweight/obesity prevalence from the National Health Interview Survey (1985-2008). PAF estimates were combined with RCC incidence from Surveillance, Epidemiology and End Results-13 to calculate annual percent changes in RCC incidence attributable (and unrelated) to overweight/obesity. We found that between 1995 and 2018, among individuals aged 60 years and older, PAF for overweight/obesity increased from 18% to 29% for all RCCs. In comparison, the PAF for smoking declined from 12% to 9%. RCC incidence increased 1.8% per year (95% confidence interval [CI] 1.5%-2.1%) overall, while RCC incidence attributable to overweight/obesity increased 3.8% per year (95%CI 3.5%-4.2%) and RCC incidence unrelated to overweight/obesity increased 1.2% per year (95% CI 0.9%-1.4%). In conclusion, overweight/obesity appears to have contributed importantly to the rising incidence of RCC in the United States since the mid-1990s. Public health interventions focused on reducing overweight and obesity could help substantially in curbing this trend. 相似文献