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   187325篇
  免费   18213篇
  国内免费   10665篇
耳鼻咽喉   1829篇
儿科学   2605篇
妇产科学   3359篇
基础医学   19170篇
口腔科学   4156篇
临床医学   23654篇
内科学   26656篇
皮肤病学   2213篇
神经病学   8754篇
特种医学   6530篇
外国民族医学   67篇
外科学   19347篇
综合类   32639篇
现状与发展   39篇
一般理论   24篇
预防医学   14335篇
眼科学   4854篇
药学   20153篇
  220篇
中国医学   11152篇
肿瘤学   14447篇
  2024年   554篇
  2023年   2480篇
  2022年   6052篇
  2021年   8807篇
  2020年   6832篇
  2019年   5638篇
  2018年   5955篇
  2017年   5950篇
  2016年   5253篇
  2015年   8301篇
  2014年   10547篇
  2013年   10817篇
  2012年   15883篇
  2011年   16906篇
  2010年   11941篇
  2009年   9870篇
  2008年   11945篇
  2007年   11366篇
  2006年   10530篇
  2005年   9291篇
  2004年   6540篇
  2003年   5760篇
  2002年   4658篇
  2001年   3891篇
  2000年   3578篇
  1999年   3194篇
  1998年   1600篇
  1997年   1479篇
  1996年   1210篇
  1995年   1136篇
  1994年   1023篇
  1993年   614篇
  1992年   977篇
  1991年   878篇
  1990年   748篇
  1989年   627篇
  1988年   572篇
  1987年   482篇
  1986年   389篇
  1985年   309篇
  1984年   191篇
  1983年   175篇
  1982年   100篇
  1981年   99篇
  1979年   145篇
  1978年   115篇
  1977年   84篇
  1974年   96篇
  1973年   73篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
Vitamin D is responsible for multiple metabolic functions in humans. Rickets are the most common disease caused by vitamin D deficiency. It is caused by poor calcium intake resulting in poor serum-ionized calcium. The purpose of this study is to develop a rapid, sensitive, and feasible method to determine the 25-hydroxy-vitamin D3 (25(OH)D3) levels in blood samples for clinical assessment. In this study, gas chromatography coupled mass spectrometry with trimethylsilyl derivatization (TMS-GC-MS) is the most suitable protocol for quantitative analyses of 25(OH)D3. Performance of method was evaluated and compared with liquid chromatography and immunoassay. Method validation has been carried out with plasma specimens. The limit of quantitation of TMS-GC-MS method is 1.5 ppb with good linear correlation. Furthermore, the dietary intake and nutritional status of vegetarian and non-vegetarians in Taiwan were assessed by our validated method. As a result, this vitamin D nutrition survey demonstrates that most Taiwanese people have insufficient vitamin D. Due to dietary habits; the male vegans may have the highest risk of vitamin D deficiency.  相似文献   
94.
目的探讨补骨脂素抗增生性瘢痕的作用机制。方法体外培养成纤维细胞,按随机数字表法分为正常组(培养正常成纤维细胞)、瘢痕组(培养增生性瘢痕成纤维细胞)、TGF-β1组(10 ng/ml TGF-β1处理增生性瘢痕成纤维细胞5 min^12 h)、Smurf2 RNA干扰组[Smad泛素化调节因子2(Smad ubiquitin regulatory factor2,Smurf2)siRNA转染增生性瘢痕成纤维细胞72 h]、补骨脂素组(10μmol/L补骨脂素处理增生性瘢痕成纤维细胞继续培养72 h)、补骨脂素+TGF-β1组(增生性瘢痕成纤维细胞加入补骨脂素培养72 h后加入TGF-β1培养6 h)。采用Western blot法检测Smurf2、α-平滑肌肌动蛋白(α-actin SMA,α-SMA)蛋白表达;RT-PCR法检测Ⅰ型胶原蛋白mRNA表达;ELISA法检测TGF-β1蛋白分泌。结果与正常组比较,瘢痕组Smurf2蛋白[(0.83±0.08)比(0.38±0.07)]表达增加(P<0.05);与瘢痕组比较,Smurf2 RNA干扰组TGF-β1[(2.2±0.18)比(4.2±0.47)]表达降低(P<0.05);TGF-β1组Smurf2[(0.71±0.06)比(0.42±0.04)]、α-SMA[(1.42±0.12)比(0.91±0.09)]蛋白表达增加(P<0.05),Ⅰ型胶原蛋白mRNA[(0.72±0.09)比(0.41±0.07)]表达增加(P<0.05);补骨脂素组Smurf2[(0.05±0.01)比(0.42±0.04)]、α-SMA[(0.71±0.07)比(0.91±0.09)]蛋白表达降低(P<0.05),Ⅰ型胶原蛋白mRNA表达[(0.12±0.04)比(0.41±0.07)]降低(P<0.05)。结论补骨脂素可能通过TGF-β1/Smurf2信号通路抑制α-SMA蛋白表达,从而降低Ⅰ型胶原蛋白表达,起到抑制瘢痕形成的作用。  相似文献   
95.
96.
目的探讨家庭逆境致精神病理症状结局的累积性与关键期效应,为预防与干预逆境伤害提供依据。方法2017年12月,采用方便抽样的方法选取安徽省阜阳地区2所农村学校的710名青少年。采用《童年期不良经历问卷》评估家庭逆境,《MacArthur健康与行为问卷》评价内化症状和外化症状。采用多元线性回归分析家庭逆境发生时间与数量和精神病理症状的关联。结果持续家庭逆境组与内化症状、外化症状增加均有相关性[β值(95%CI)分别为0.35(0.15~0.54),0.16(0.01~0.32)]。家庭逆境数量为2和≥3与内化症状[β值(95%CI)分别为0.20(0.04~0.36),0.42(0.24~0.60)]、外化症状[β值(95%CI)分别为0.14(0.01~0.26),0.23(0.09~0.37)]增加有关。在仅童年期家庭逆境中,家庭逆境数量为2和≥3的内化症状[β值(95%CI)分别为0.23(0.06~0.41),0.34(0.11~0.58)]、外化症状[β值(95%CI)分别为0.17(0.02~0.31),0.21(0.02~0.39)]的风险增高。在持续家庭逆境组中,逆境数量≥3与内化症状、外化症状相关[(β值(95%CI)分别为0.56(0.31~0.82),0.24(0.02~0.45)]。仅青春期家庭逆境与精神病理症状无关。结论家庭逆境的多次发生可增加精神病理症状风险,童年期可能是家庭逆境致精神病理症状的关键期。  相似文献   
97.
98.
Abstract

Background and aim: Capsule retention is the most common adverse event associated with video capsule endoscopy. The use of double-balloon enteroscopy-assisted capsule endoscope retrieval has been increasingly reported in recent years. However, evidence is limited regarding its success rate, associated factors, and subsequent clinical outcomes.

Methods: A systematic review of relevant studies published before January 2019 was performed. Successful retrieval rate and associated factors, rate of endoscopic balloon dilation, and outcomes after double-balloon enteroscopy were summarized and pooled.

Results: Within 154 associated original articles, 12 including 150 cases of capsule retrieval by double-balloon enteroscopy were included. The estimated pooled successful retrieval rate was 86.5% (95% confidence interval, 75.6–95.1%). Anterograde approach and capsules retained in the jejunum or trapped by malignant strictures were associated with a higher successful retrieval rate than the retrograde approach (62/83 [74.7%] vs. 10/38 [26.3%], p?<?.001) and capsules retained in the ileum (41/41 [100.0%] vs. 43/58 [74.1%], p?<?.001) or trapped by benign strictures (21/21 [100.0%] vs. 65/83 [78.3%], p?=?.043). Endoscopic balloon dilation was performed in 38.8% (95% confidence interval, 22.3–56.3%) of patients with benign strictures. Two perforations (1.3%) were reported as severe adverse events after double-balloon enteroscopy. A significantly lower surgery rate was found among cases with successful video capsule removal compared with unsuccessful cases (7.2% vs. 38.5%, p?=?.002).

Conclusions: Double-balloon enteroscopy is feasible and safe for removing retained video capsule endoscopes, and its use could decrease the need for surgery in patients with benign strictures and facilitate subsequent surgery in patients with malignant strictures.  相似文献   
99.
Objective To analyze the early mortality and related risk factors of new hemodialysis patients in Zhejiang province, and provide basis for reducing the death risk of hemodialysis patients. Methods The early mortality and related factors of new hemodialysis patients from January 1, 2010 to June 30, 2018 were retrospectively analyzed using the database of Zhejiang province hemodialysis registration. The early mortality was defined as death within 90 days of dialysis. Cox regression model was used to analyze the related risk factors of the early mortality in hemodialysis patients. Results The mortality was the highest in the first month after dialysis (46.40/100 person year), and gradually stabilized after three months. The early mortality was 25.33/100 person year. The mortality within 120 days and 360 days were 21.40/100 person year and 11.37/100 person year, respectively. The elderly (≥65 years old, HR=1.981, 95%CI 1.319-2.977, P<0.001), primary tumor (HR=3.308, 95%CI 1.137-5.624, P=0.028), combined with tumors (not including the primary tumor, HR=2.327, 95%CI 1.200-4.513, P=0.012), temporary catheter (the initial dialysis pathway, HR=3.632, 95%CI 1.806-7.307, P<0.001), lower albumin (<30 g/L, HR=2.181, 95%CI 1.459-3.260, P<0.001), lower hemoglobin (every 0.01 g/L increase, HR=0.861, 95%CI 0.793-0.935, P=0.001), lower high density lipoprotein (<0.7 mmol/L, HR=1.796, 95%CI 1.068-3.019, P=0.027) and higher C reactive protein (≥40 mg/L, HR=1.889, 95%CI 1.185-3.012, P=0.008) were the risk factors of early death for hemodialysis patients. Conclusions The early mortality of hemodialysis patients is high after dialysis, and gradually stable after 3 months. The elderly, primary tumor, combined with tumors, the initial dialysis pathway, lower albumin, lower hemoglobin, lower high density lipoprotein and higher C reactive protein are the risk factors of early death for hemodialysis patients.  相似文献   
100.
重症心源性肺水肿伴休克患者的机械通气治疗   总被引:3,自引:0,他引:3  
目的研究重症心源性肺水肿伴休克患者机械通气(MV)治疗时通气压力的选择对预后的影响。方法将符合标准的22例患者分为两组对照组9例,常规给予较低通气压力和加强药物治疗;治疗组13例,适当增加通气压力。观察血压、临床症状和动脉血气的变化。结果调整MV后30分钟时,治疗组收缩压迅速由(95±12)mmHg升至(130±15)mmHg(P<0.001),呼吸频率(RR)由(38±11)次/min降至(27±6)次/min(P<0.005),心率(HR)由(126±15)次/min降至(105±12)次/min(P<0.001);对照组上述指标变化不明显。2小时后治疗组的升压药用量减少(70±15)%,对照组则增加(20±5)%;同时在吸氧浓度不变的情况下,治疗组的PaO2由(81±12)mmHg升至(140±15)mmHg(P<0.001),明显高于对照组PaO2的改善。24~48小时内治疗组11例患者(85%)停用升压药,对照组2例(22%)停用。最终治疗组100%的患者好转出院,对照组为45%(P<0.05)。结论与低压力通气相比,适当增加MV通气压力不仅可迅速改善重症心源性水肺肿伴休克患者的低氧血症,也可迅速升高血压,改善心功能,降低病死率。  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