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   19180篇
  免费   1671篇
  国内免费   1386篇
耳鼻咽喉   185篇
儿科学   146篇
妇产科学   246篇
基础医学   2273篇
口腔科学   215篇
临床医学   2291篇
内科学   3382篇
皮肤病学   189篇
神经病学   929篇
特种医学   721篇
外国民族医学   11篇
外科学   2047篇
综合类   3167篇
一般理论   2篇
预防医学   1075篇
眼科学   562篇
药学   2032篇
  15篇
中国医学   964篇
肿瘤学   1785篇
  2024年   63篇
  2023年   318篇
  2022年   746篇
  2021年   960篇
  2020年   677篇
  2019年   653篇
  2018年   729篇
  2017年   573篇
  2016年   609篇
  2015年   856篇
  2014年   1054篇
  2013年   865篇
  2012年   1371篇
  2011年   1514篇
  2010年   860篇
  2009年   719篇
  2008年   1043篇
  2007年   1002篇
  2006年   971篇
  2005年   953篇
  2004年   640篇
  2003年   591篇
  2002年   516篇
  2001年   459篇
  2000年   511篇
  1999年   455篇
  1998年   343篇
  1997年   303篇
  1996年   269篇
  1995年   258篇
  1994年   170篇
  1993年   125篇
  1992年   166篇
  1991年   158篇
  1990年   127篇
  1989年   123篇
  1988年   112篇
  1987年   99篇
  1986年   95篇
  1985年   61篇
  1984年   29篇
  1983年   23篇
  1982年   11篇
  1981年   17篇
  1980年   10篇
  1979年   7篇
  1978年   7篇
  1977年   3篇
  1976年   4篇
  1974年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
AimThe investigation aims to evaluate the potential effect of Shugan Granule (SGKL) on the gut, brain, and behaviors in rats exposed to chronic restraint stress (CRS).MethodsThe fecal microbiota and metabolite changes were studied in rats exposed to CRS and treated with SGKL (0.1 mg/kg/day). Depressive behaviors of these rats were determined through an open‐field experiment, forced swimming test, sucrose preference, and weighing. Moreover, LPS‐stimulated microglia and CRS‐stimulated rats were treated with SGKL to investigate the regulation between SGKL and the PI3K/Akt/pathway, which is inhibited by LY294002, a PI3K inhibitor.Results(i) SGKL improved the altered behaviors in CRS‐stimulated rats; (ii) SGKL ameliorated the CRS‐induced neuronal degeneration and tangled nerve fiber and also contributed to the recovery of intestinal barrier injury in these rats; (iii) SGKL inhibited the hippocampus elevations of TNF‐α, IL‐1β, and IL‐6 in response to CRS modeling; (iv) based on the principal coordinates analysis (PCoA), SGKL altered α‐diversity indices and shifted β‐diversity in CRS‐stimulated rats; (v) at the genus level, SGKL decreased the CRS‐enhanced abundance of Bacteroides; (vi) Butyricimonas and Candidatus Arthromitus were enriched in SGKL‐treated rats; (vii) altered gut microbiota and metabolites were correlated with behaviors, inflammation, and PI3K/Akt/mTOR pathway; (viii) SGKL increased the LPS‐decreased phosphorylation of the PI3K/Akt/mTOR pathway in microglia and inhibited the LPS‐induced microglial activation; (ix) PI3K/Akt/mTOR pathway inactivation reversed the SGKL effects in CRS rats.ConclusionSGKL targets the PI3K/Akt/mTOR pathway by altering gut microbiota and metabolites, which ameliorates altered behavior and inflammation in the hippocampus.  相似文献   
92.
Human cytomegalovirus (CMV) utilizes different glycoproteins to enter into fibroblast and epithelial cells. A trimer of glycoproteins H, L, and O (gH/gL/gO) is required for entry into all cells, whereas a pentamer of gH/gL/UL128/UL130/UL131A is selectively required for infection of epithelial, endothelial, and some myeloid-lineage cells, but not of fibroblasts. Both complexes are of considerable interest for vaccine and immunotherapeutic development but present a conundrum: gH/gL-specific antibodies have moderate potency yet neutralize CMV entry into all cell types, whereas pentamer-specific antibodies are more potent but do not block fibroblast infection. Which cell types and neutralizing activities are important for protective efficacy in vivo remain unclear. Here, we present evidence that certain CMV strains have evolved polymorphisms in gO to evade trimer-specific neutralizing antibodies. Using luciferase-tagged variants of strain TB40/E in which the native gO is replaced by gOs from other strains, we tested the effects of gO polymorphisms on neutralization by monoclonal antibodies (mAbs) targeting four independent epitopes in gH/gL that are common to both trimer and pentamer. Neutralization of fibroblast entry by three mAbs displayed a range of potencies that depended on the gO type, a fourth mAb failed to neutralize fibroblast entry regardless of the gO type, while neutralization of epithelial cell entry by all four mAbs was potent and independent of the gO type. Thus, specific polymorphisms in gO protect the virus from mAb neutralization in the context of fibroblast but not epithelial cell entry. No influence of gO type was observed for protection against CMV hyperimmune globulin or CMV-seropositive human sera, suggesting that antibodies targeting protected gH/gL epitopes represent a minority of the polyclonal neutralizing repertoire induced by natural infection.  相似文献   
93.
Although the mortality rates of gastric cancer (GC) are gradually declining, gastric cancer is still the fourth leading cause of cancer-related death worldwide. This may be due to the high rate of patients who are diagnosed with GC at advanced stages. However, in countries such as Japan with endoscopic screening systems, more than half of GCs are discovered at an early stage, enabling endoscopic resection (ER). Especially after the introduction of endoscopic submucosal dissection (ESD) in Japan around 2000, a high en bloc resection rate allowing pathological assessment of margin and depth has become possible. While ER is a diagnostic method of treatment and may not always be curative, it is widely accepted as standard treatment because it is less invasive than surgery and can provide an accurate diagnosis for deciding whether additional surgery is necessary. The curability of ER is currently assessed by the completeness of primary tumor removal and the possibility of lymph node metastasis. This review introduces methods, indications, and curability criteria for ER of EGC. Despite recent advances, several problems remain unsolved. This review will also outline the latest evidence concerning future issues.  相似文献   
94.
Owing to their low minimal environmental risk and other ethical considerations, plant-derived sterilants are used to control rodent populations. However, the effects of plant-derived sterilants are not immediate, and their efficacy on rodent control is controversial, which negatively affects sterilant research and application. Here, a meta-analysis of the available literature was conducted to evaluate the effects of two plant-derived sterilants, triptolide and curcumol, on rodent populations. Using a random-effects and a fixed-effects model, we calculated the weighted mean difference (WMD) and relative risk (RR) and their corresponding 95% confidence intervals (95% CIs). After the application of plant-derived sterilants, the rodent population density tended to decrease. Three outcome-related measures in rodents, i.e., capture rate (RR = 0.31, 95% CI [0.20, 0.47]), pregnancy rate (RR = 0.49, 95% CI [0.40, 0.61]), and sperm survival rate (WMD = −17.53, 95% CI [−28.96, −6.06]), significantly decreased, as shown by a significant reduction of ovarian, uterine, and testicular organ coefficients. However, the number of effective rodent holes did not change significantly after the interventions, indicating that the studied sterilants did not directly eradicate the rodent populations. This study provides a theoretical basis for elucidating the inhibitory mechanisms of plant-derived sterilants on rodent populations and for the rational use of these sterilants.  相似文献   
95.
INTRODUCTIONThe stillbirth rate (SBR) is an important public health indicator. We studied the distribution of maternal and fetal characteristics and time trends of the SBR at KK Women’s and Children’s Hospital (KKH), Singapore, from 2004 to 2016 based on various definitions of stillbirth.METHODSData was obtained from the Data Warehouse and Stillbirth Reporting System of KKH from 2004 to 2016. SBRs were calculated based on three definitions (fetal deaths at ≥ 20 weeks, 24 weeks or 28 weeks of gestation per 1,000 total births) and were described with maternal and fetal characteristics, and by year.RESULTSFrom 2004 to 2016, the SBR declined by 44.7%, 25.5% and 18.9% based on Definitions I, II and III, respectively. The SBR at KKH in 2016 was 5.2 (Definition I), 4.1 (Definition II) and 3.0 (Definition III) per 1,000 total births. The SBR was significantly higher in women aged ≥ 35 years, nulliparas and female fetuses. The number of live births at 24–27+6 weeks of gestation was more than four times higher than that of stillbirths (822 vs. 176). There were 104 (12.7%) neonatal deaths during this gestation period, giving a high survival rate of 87.3%.CONCLUSIONThe SBR in KKH is relatively lower than that in other developed countries. There is a need to consider revising our hospital and national definitions of the stillbirth lower boundary from 28 weeks to 24 weeks of gestation. This would allow us to make better comparisons with other developed countries, in line with improvements in healthcare.  相似文献   
96.
目的:对藏族青年人的头面部特征进行美容学分析,为藏族体质人类学、民族美容学和整形外科研究积累资料。方法:活体观察,活体测量,数码摄像和电脑测量分析。结果:藏族青年面部的黄金比例,除外眦距/面宽,口裂宽/眼外眦两项与黄金比例差异较大外,其余均接近标准(0.618);男性面上下部较长,中间较短。女性下部最长,男女性中央部较窄,外侧较宽,但面部整体左右对称较好;藏族青年鼻、唇和颏三者位置关系较高的符合美容学要求。同时,我们对面部纵横行方向的数据进行相关性分析,得出28组回归方程。结论:初步得出了藏族青年人头面部特征和美容学数据库。  相似文献   
97.
98.
目的探讨18F-FDG PET/CT全身显像在不明原发灶肿瘤(CUP)诊断中的临床应用价值。方法回顾分析46例于2015年2月至2016年6月在我院行常规检查未能发现肿瘤原发灶而进一步行18F-FDG PET/CT全身显像查找肿瘤原发灶的转移性肿瘤患者的资料。PET/CT图像分析采用视觉及半定量分析方法。通过病理活检和(或)临床综合诊断、临床随访对结果进行评价。结果46例患者中,18F-FDG PET/CT显像找到原发肿瘤33例,均经过病理活检及临床随访证实;13例未发现原发病灶。18F-FDG PET/CT对不明肿瘤原发灶的检出率为71.7%(33/46),其中阳性患者中淋巴瘤3例、胃癌2例、食管癌4例、卵巢癌3例、肺癌14例、肝癌2例、尿路上皮癌1例、鼻咽癌2例、多发性骨髓瘤1例、降结肠癌1例。转移方式主要有淋巴结转移32例、骨转移20例、肝转移13例、肺转移9例、胸膜腹膜转移5例、肾上腺转移3例、脑转移4例、皮下转移3例、心包膜转移1例。结论18F-FDG PET/CT全身显像对CUP的检出率显著优于一般常规检查,对临床指导治疗有着重要意义。  相似文献   
99.
Little is known about esophageal high-grade intraepithelial neoplasia dominated by cytological atypia (HGINc). We aimed to elucidate the endoscopic features of HGINc compared with esophageal high-grade intraepithelial neoplasia dominated by architectural atypia (HGINa). All patients pathologically diagnosed as esophageal high-grade intraepithelial neoplasia after endoscopic submucosal dissection at our center between January 2018 and December 2019 were included in this study. According to the pathological diagnosis, the patients were divided into two groups: HGINa group and HGINc group. Basic characteristics and endoscopic information were collected in detail. Data were analyzed statistically. Binary logistic regression was performed and a predictive model for HGINc was established. Then we evaluated its predictive value and built a nomogram for clinical application. A total of 175 patients were included in this study (126 with HGINa and 49 with HGINc). Among 228 lesions found in all patients, there were 148 HGINa and 80 HGINc. The independent relevant factors for HGINc were tobacco and alcohol usage, color, and gross type. To predict risk of HGINc, a three-factor model (TFM) was established with a highest area under curve (AUC) as 0.869 (95% CI, 0.852, 0.939). When the cut-off value was set as 0.3569184, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for HGINc was 81.14%, 88.75%, 77.03%, 67.62%, and 92.68%, respectively. HGINc differs greatly in endoscopic features from HGINa in our study. It’s important to reduce misdiagnosis that our model was established with good predictive value for clinical application.  相似文献   
100.
他克莫司对小鼠毛囊生长周期的影响   总被引:2,自引:0,他引:2  
Tian T  Fan WX  Dai YQ  Liu LP 《中国医学科学院学报》2007,29(2):209-212,I0003
目的探讨他克莫司对小鼠毛囊生长周期的影响及其作用机制。方法应用苏木素-伊红(HE)染色及RT-PCR法研究他克莫司对小鼠毛囊生长周期影响。结果脱毛后第5天他克莫司组及米诺地尔组小鼠背部毛囊呈生长期Ⅴ状态,而凡士林组毛囊呈生长期Ⅲ状态。在脱毛后第5天他克莫司组及米诺地尔组小鼠背部皮肤检测到血管内皮细胞生长因子及肝细胞生长因子表达,而凡士林组未能检测到。结论他克莫司可通过促进毛囊提前进入生长期Ⅴ而达到促进毛发生长的作用,这种促进作用可能与血管内皮细胞生长因子及肝细胞生长因子作用有关。  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