首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3393篇
  免费   287篇
  国内免费   206篇
耳鼻咽喉   52篇
儿科学   44篇
妇产科学   26篇
基础医学   439篇
口腔科学   53篇
临床医学   433篇
内科学   498篇
皮肤病学   63篇
神经病学   258篇
特种医学   94篇
外国民族医学   1篇
外科学   339篇
综合类   495篇
一般理论   2篇
预防医学   237篇
眼科学   70篇
药学   332篇
  5篇
中国医学   120篇
肿瘤学   325篇
  2024年   12篇
  2023年   50篇
  2022年   102篇
  2021年   122篇
  2020年   100篇
  2019年   97篇
  2018年   119篇
  2017年   78篇
  2016年   86篇
  2015年   151篇
  2014年   157篇
  2013年   167篇
  2012年   202篇
  2011年   262篇
  2010年   174篇
  2009年   128篇
  2008年   160篇
  2007年   192篇
  2006年   195篇
  2005年   194篇
  2004年   147篇
  2003年   131篇
  2002年   115篇
  2001年   91篇
  2000年   84篇
  1999年   103篇
  1998年   48篇
  1997年   44篇
  1996年   38篇
  1995年   24篇
  1994年   27篇
  1993年   22篇
  1992年   36篇
  1991年   33篇
  1990年   31篇
  1989年   17篇
  1988年   18篇
  1987年   16篇
  1986年   11篇
  1985年   6篇
  1984年   11篇
  1983年   11篇
  1982年   6篇
  1981年   5篇
  1979年   7篇
  1978年   6篇
  1975年   5篇
  1973年   9篇
  1968年   4篇
  1966年   4篇
排序方式: 共有3886条查询结果,搜索用时 15 毫秒
91.

Objective

MicroRNA-93 (miR-93) is upregulated in the urine of patients with bladder cancer (BC). Here, we investigated the role of miR-93 in BC progression and explored the underlying mechanism.

Methods

miR-93 expression in BC tissues and cells was detected by real time-polymerase chain reaction. The effects of miR-93 and pigment epithelium-derived factor (PEDF) on cell proliferation and invasion were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell assays. The binding of miR-93 to the 3′-untranslated region of PEDF was identified by the luciferase reporter assay.

Results

miR-93 expression was higher in BC tissues than in normal controls, and its expression was associated with tumor stage and node stage. Inhibition of miR-93 suppressed the proliferation and invasion of BC cells. PEDF was identified as a target of miR-93 and shown to mediate the effect of miR-93 on cell proliferation and invasion.

Conclusions

The present data suggested that miR-93 promoted BC cell proliferation and invasion by targeting PEDF, providing new biomarkers and targets for BC diagnosis and treatment.  相似文献   
92.
Occupation affects bone mineral density (BMD); however, only few studies have been published. This study evaluated the effect of working time during a day on BMD. The cross-sectional study involved 18- to 50-year-old people who reported their working time and were measured for BMD using dual-energy X-ray absorptiometry in the Fourth Korea National Health and Nutrition Examination Survey 2009. The time period of work was divided into “daytime” and “other than daytime.” The other-than-daytime group included evening time, nighttime, regular shift time, and irregular shift time. Among 3,005 subjects, 2,378 were daytime workers and 627 were other-than-daytime workers. The mean BMD of the total femur and lumbar spine were significantly lower in other-than-daytime workers compared to daytime workers (femur 0.948 vs. 0.966 g/cm2, respectively, p = 0.001; lumbar spine 0.976 vs. 0.988 g/cm2, respectively, p = 0.023). The other-than-daytime group had lower levels of serum 25-hydroxyvitamin D than the daytime group (16.3 vs. 17.6 ng/mL, p < 0.001). The proportion of osteopenia (T score < ?1.0) was higher in the other-than-daytime than the daytime group (34.3 vs. 29.1 %, p = 0.014). After adjustment for age, sex, socioeconomic status, lifestyle factors, daily intake of calcium, and vitamin D level, the relative risks of osteopenia of regular-shift and irregular-shift workers were significantly higher (1.65, 95 % CI 1.05–2.60; 1.78, 95 % CI 1.09–2.89) than those of daytime workers. These data suggest that other-than-daytime working, especially regular and irregular shift working, is associated with decreased BMD and increased risk for osteopenia in Korean adults.  相似文献   
93.
Summary. A novel genotype of hepatitis E virus (HEV) isolated from rabbits is reported. The aim of this study was to confirm and further investigate the prevalence of the novel HEV genotype in rabbits in China. Sera and faecal samples were collected from farmed rex rabbits in Beijing, China. All serum samples were tested for anti‐HEV antibody by EIA. Both the serum and the faecal samples were evaluated for detection of HEV RNA using a nested RT‐PCR assay. The nucleotide sequences of rabbit HEV were then analysed, and sequence homology of rabbit HEV compared against human HEV genotypes 1–4, and avian HEV. Results: The prevalence of positive serum anti‐HEV from rex rabbits was 54.62% (65/119). The detection rate of HEV RNA using ORF2 primers was 6.96% (8/115) amongst rabbit faecal samples. All eight amplicons shared 98.3–100% nucleotide homology with each other and had identities of 75.8–78.6%, 73.9–75.0%, 77.5–81.0%, 74.2–78.6% and 54.8–57.6% with the corresponding regions of genotypes 1–4 and avian HEV, respectively. Phylogenetic analysis showed that the eight sequences formed one individual branch and were on the same branch with GDC9 and GDC46, both of which were reported to be a novel genotype of HEV isolated from rabbits. The conclusion is that this study provides further information about HEV infecting rabbits, which may be a new animal host of HEV, as well as genetical evidence of a new mammalian genotype of HEV.  相似文献   
94.
Aim: In diabetes mellitus (DM) patients, left ventricular dysfunction is widely evaluated and established by conventional diagnostic methods, whereas right ventricular (RV) function is not as sufficiently evaluated. The aim of this study is to assess the preclinical effects of DM on RV function by using novel Tissue Doppler Imaging (TDI)‐derived indices. Methods: The study included 96 patients with type II DM [60 with DM only and 36 patients with coexisting DM and hypertension (DMHT)] and 40 healthy controls. Conventional parameters and TDI‐derived systolic velocities of tricuspid annulus [isovolumic myocardial acceleration (IVA), peak myocardial velocity during isovolumic contraction (IVV), peak systolic velocity during ejection period (Sa), RV Tei index] were measured. Results: TDI‐derived RV IVA was significantly lower in both DM and DMHT patients compared to controls indicating subclinical impairment in RV systolic function in the study patients (P = 0,0001). However RV IVA was similar in DM and DMHT subgroup supporting RV systolic impairment in DM was independent from HT. In correlation analysis, RV IVA was significantly correlated with the existence of diabetic nephropathy (r =?0,38; P = 0,003), retinopathy (r =?0,35; P = 0,006), insulin resistance (r =?0,52; P = 0,0001). Conclusions: Diabetes is associated with subclinical RV systolic dysfunction, regardless of coexisting hypertension. Tissue Doppler‐derived IVA; is a novel, non‐invasive parameter which may be used in early detection of RV systolic dysfunction in patients with DM. (Echocardiography 2010;27:1211‐1218)  相似文献   
95.
目的:建立同时测定扑麻滴鼻液中盐酸麻黄碱和马来酸氯苯那敏含量的HPLC方法。方法:采用:PurospherSTAR RP18色谱柱(150 mm×4.6 mm,5μm),以磷酸盐缓冲液(p H 3.0±0.1)-乙腈(82∶18)为流动相,流速为1.0 ml·min-1,在210nm波长处同时检测盐酸麻黄碱和马来酸氯苯那敏,柱温35℃,进样量20μl。结果:盐酸麻黄碱和马来酸氯苯那敏分别在19.81~118.85μg·ml-1和6.21~37.25μg·ml-1浓度范围内线性关系良好,r分别为0.999 6和0.999 8。平均回收率分别为100.39%(RSD=0.69%,n=9)和100.11%(RSD=0.60%,n=9)。结论:该方法快速简便、重复性、准确性好,可用于该制剂中盐酸麻黄碱和马来酸氯苯那敏的含量测定。  相似文献   
96.
This study aimed to compare the effectiveness and safety of reduced-port laparoscopic surgery (RPLS) and conventional multi-port laparoscopic (CMPLS) surgery in the treatment of gastric diseases.The PubMed, Embase, Cochrane Library, Web of Science, and Chinese Biomedical Literature databases were systematically searched for randomized controlled trials, cohort studies, and case control studies on the use of RPLS vs conventional multi-port laparoscopic surgery in treating gastric diseases from their inception until March 10, 2019. The evaluated outcomes were the operative time, blood loss, length of hospital stay, number of dissected lymph nodes, postoperative complications, and conversions. All of these were compared using Stata software version 12.0.A total of 18 studies were included, which involved 2938 patients. In studies referring to the comparison between RPLS and CMPLS in treating gastric diseases, the former showed significantly inferior in terms of operative time (P = .011) and number of dissected lymph nodes (P = .031); but superior results in terms of the estimated blood loss (P = .000) and length of hospital stay (P = .001) than the latter did; however, the rates of postoperative complications (P = .830) and conversions (P = .102) were not statistically significant between the 2 groups.RPLS and CMPLS showed comparable effectiveness and safety in the treatment of gastric diseases in our meta-analysis. Based on the current evidence, we believe that RPLS is an efficacious surgical alternative to CMPLS in the management of gastric diseases because of the shorter hospital stay and reduced blood loss. However, large-scale, well-designed, multicenter studies are needed to further confirm the results of this study.  相似文献   
97.
Chen  Congying  Bu  Lingling  Liu  Huan  Rang  Yifeng  Huang  Huiying  Xiao  Xueman  Ou  Genghua  Liu  Chunhong 《Metabolic brain disease》2022,37(5):1451-1463
Metabolic Brain Disease - 1,4-butanediol (1,4-BD) is a known γ-hydroxybutyric acid (GHB) precursor which affects the nervous system after ingestion, leading to uncontrolled behavioral...  相似文献   
98.
目的:观察APP/PS1双转基因小鼠海马内Aβ沉积的形态特征。方法:以10月龄雄性APP/PS1双转基因小鼠和C57BL/6小鼠为研究对象,采用Aβ免疫组化和透射电镜技术,观察海马部位Aβ的沉积情况及相关的病理特征。结果:在双转基因小鼠海马内存在致密性神经炎性斑块及营养障碍性突起,但脑微血管壁的Aβ沉积不甚明显;营养障碍性突起及神经细胞、微血管内皮细胞、周细胞内存在大量的自噬泡及次级溶酶体,提示该模型存在自噬溶酶体途径功能紊乱。结论:该鼠模拟了AD的老年斑及相关退行性变等病理改变,其中可能伴有细胞多种代谢的变化及血脑屏障功能的变化。从老年斑角度而言,该动物是成功的阿尔茨海默病动物模型,可用于AD的生化、病理研究及新治疗方法的探索。  相似文献   
99.
100.
The term ‘nurse’ (hushi—’caring scholar’) did not enter the Chinese language until the early 20th century. Modern nursing—a fundamentally Western notion popularized by Nightingale and introduced to China in 1884—profoundly changed the way care of the sick was practiced. For 65 years, until 1949, nursing developed in China as a transnational project, with Western and Chinese influences shaping the profession of nursing in ways that linger today. Co‐authored by Chinese, Canadian, and American nurses, this paper examines the early stages of nursing in one province of China as an exemplar of the transnational nature of nursing development. By identifying sociopolitical influences on the early development of nursing in Shandong, the authors aimed not only to contribute to the nascent body of knowledge on China nursing history, but also to heighten readers’ sensitivity to the existence of historical echoes, residue, and resonances in their own nursing practices. Tracing current issues, values, or practices back to their roots provides context and helps us to better understand the present. Whether we are aware of the details or not, the gestalt of nursing practice in a particular place has been shaped by its history—including in Shandong province in China.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号