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   7421篇
  免费   430篇
  国内免费   232篇
耳鼻咽喉   63篇
儿科学   83篇
妇产科学   97篇
基础医学   642篇
口腔科学   498篇
临床医学   549篇
内科学   673篇
皮肤病学   327篇
神经病学   451篇
特种医学   188篇
外科学   788篇
综合类   898篇
现状与发展   2篇
预防医学   574篇
眼科学   192篇
药学   1683篇
  3篇
中国医学   266篇
肿瘤学   106篇
  2023年   77篇
  2022年   210篇
  2021年   303篇
  2020年   203篇
  2019年   185篇
  2018年   169篇
  2017年   184篇
  2016年   214篇
  2015年   222篇
  2014年   393篇
  2013年   468篇
  2012年   364篇
  2011年   455篇
  2010年   336篇
  2009年   306篇
  2008年   347篇
  2007年   355篇
  2006年   309篇
  2005年   292篇
  2004年   256篇
  2003年   229篇
  2002年   182篇
  2001年   136篇
  2000年   127篇
  1999年   125篇
  1998年   110篇
  1997年   117篇
  1996年   117篇
  1995年   107篇
  1994年   116篇
  1993年   104篇
  1992年   70篇
  1991年   67篇
  1990年   87篇
  1989年   81篇
  1988年   58篇
  1987年   53篇
  1986年   49篇
  1985年   78篇
  1984年   64篇
  1983年   46篇
  1982年   53篇
  1981年   52篇
  1980年   46篇
  1979年   25篇
  1978年   33篇
  1977年   19篇
  1976年   27篇
  1975年   15篇
  1974年   14篇
排序方式: 共有8083条查询结果,搜索用时 15 毫秒
1.
??Objective    To observe the effects of lithium chloride pretreatment on cognitive ability of aged rats after oral and maxillofacial surgery. Methods    A total of 48 aged male SD rats??18 ~ 20 months old??weight 550 ~ 700 g?? were bought from the Experimental Animal Center of China Medical University . These rats were randomly divided into three groups??including the normal control group??group C??n=16????surgery and anesthesia group??group O??n=16????and lithium chloride preconditioning group??group L??n=16??.Rats in each group were randomly divided into two parts??one part was given Morris water maze test three days after the surgery and its characteristics of behavior tested. Another part was decapitated 24 h after the surgery and extracted and the hippocampus brain separated at the same time. Test expression content of IL-1β GSK-3β p-GSK-3β??ser9??in the hippocampus by Elisa and Western blotting detection method respectively. Results    Morris water maze test showed that??the first day after surgery??latencies of group L and O were significantly longer than group C??compared with group C in swimming distance?? latency and swim distances of group L were shorter than group O. With the comparison of multiple analysis of variance??differences were statistically significant??P??0.05??. Groups L and O in the second day were slightly shortened compared to the first day??on the third day after surgery it has also improved over the second day. Space exploration experiments in rats showed that??the dwell time of group C was significantly longer in the platform quadrant and the frequency of crossing the platform also increased compared with groups L and O. In addition??group L and group O were higher in IL-β levels than group C??the difference being statistically significant by analysis of variance??P??0.05????but group L was significantly lower compared with group O??the difference being statistically significant??P??0.05??. The content of GSK-3β of three groups were of no significant difference??P > 0.05????but p-GSK-3β??ser9??content was significantly lower in group L and O than in group C. The content of GSK-3β of group L was higher than in group O??the difference being statistically significant??P??0.05??. Conclusion    Pretreatment with lithium chloride in postoperative aged rats can inhibit the expression of inflammatory cytokines and increase GSK-3β phosphorylation in the hippocampus cells??so p-GSK-3β??ser9??upregulates and inhibites  the apoptosis of brain cells??thereby improved cognitive abilities after the cavity and maxillofacial surgery.  相似文献   
2.
3.
4.

Objective

Hypertonic saline (HTS) has potent immune and vascular effects. We assessed recipient pretreatment with HTS on allograft function in a porcine model of heart transplantation and hypothesized that HTS infusion would limit endothelial and left ventricular (LV) dysfunction following transplantation.

Methods

Heart transplants were performed after 6 hours of cold ischemic storage. Recipient pigs were randomized to treatment with or without HTS (7.5% NaCl) before cardiopulmonary bypass (CPB). Using a myograft apparatus, coronary artery endothelial-dependent (Edep) and -independent (Eind) relaxation was assessed. LV performance was determined using pressure-volume loop analysis. Pulmonary interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α expression was measured.

Results

Weaning from CPB and LV performance after transplantation were improved in HTS-treated animals. Successful weaning from CPB was greater in the HTS-treated hearts (8 of 8 vs 2 of 8; P < .05). Mean LV functional recovery was improved in the HTS-treated animals, as assessed by preload recruitable stroke work (65 ± 10% vs 27 ± 10%; P < .001) and end-systolic elastance (55 ± 7% vs 37 ± 4%; P < .001). Treatment with HTS resulted in improved Edep (mean maximum elastance [Emax], 56 ± 5% vs 37 ± 7%; P < .001) and Eind (mean Emax%, 77 ± 6% vs 52 ± 4%; P < .001) vasorelaxation compared with control. Pulmonary expression of IL-2, IL-6, and TNF-α increased following transplantation, whereas HTS therapy attenuated IL production (P < .001). Transplantation increased plasma TNF-α levels and LV TNF-α expression, whereas HTS prevented this up-regulation (P < .001).

Conclusions

Recipient HTS pretreatment preserves allograft vasomotor and LV function, and HTS therapy limits CPB-induced injury. HTS may be a novel recipient intervention to prevent graft dysfunction.  相似文献   
5.
6.
7.
化学药合成过程中水分残留不利于反应的进行,还影响药物及制剂的稳定性、理化性质、溶出及药理作用等,因此水分几乎是大多数药物合成中的必测项目,通过有效除水严格控制反应体系中水分的含量至关重要。本文综述了水分的存在形式,常见除水剂和脱水剂的种类、作用原理与除水能力,以及在药物合成的应用,为药物合成反应中水分的去除提供参考。  相似文献   
8.

Background

We have recently shown that human epididymis protein 4 (HE4) levels correlate with the severity of cystic fibrosis (CF) lung disease. However, there are no data on how HE4 levels alter in patients receiving CFTR modulating therapy.

Methods

In this retrospective clinical study, 3 independent CF patient cohorts (US-American: 29, Australian: 12 and Irish: 19 cases) were enrolled carrying at least one Class III CFTR CF-causing mutation (p.Gly551Asp) and being treated with CFTR potentiator ivacaftor. Plasma HE4 was measured by immunoassay before treatment (baseline) and 1–6?months after commencement of ivacaftor, and were correlated with FEV1 (% predicted), sweat chloride, C-reactive protein (CRP) and body mass index (BMI).

Results

After 1?month of therapy, HE4 levels were significantly lower than at baseline and remained decreased up to 6?months. A significant inverse correlation between absolute and delta values of HE4 and FEV1 (r?=??0.5376; P?<?.001 and r?=??0.3285; P?<?.001), was retrospectively observed in pooled groups, including an independent association of HE4 with FEV1 by multiple regression analysis (β?=??0.57, P?=?.019). Substantial area under the receiver operating characteristic curve (ROC-AUC) value was determined for HE4 when 7% mean change of FEV1 (0.722 [95% CI 0.581–0.863]; P?=?.029) were used as classifier, especially in the first 2?months of treatment (0.806 [95% CI 0.665–0.947]; P?<?.001).

Conclusions

This study shows that plasma HE4 levels inversely correlate with lung function improvement in CF patients receiving ivacaftor. Overall, this potential biomarker may be of value for routine clinical and laboratory follow-up of CFTR modulating therapy.  相似文献   
9.
目的 分析腰椎间盘突出症手术疗效不佳的原因,探讨提高疗效的方法。方法 随访本院1993-2003年腰椎间盘突出症行后路髓核摘除术病例236例,对术后腰腿痛症状未缓解或症状消失后再复发者复查X片、CT或MRI了解病因。结果手术疗效不佳者25例。疗效不佳的主要原因为残留髓核再突出、术后脊柱不稳倾向增加、对侧隐窝狭窄认识不足、神经根损伤、极外侧型椎问盘突出漏切、感染、术后椎管内瘢痕黏连等。全椎板切除术较椎板问开窗术更易发生椎管内瘢痕黏连(P<0.01)。结论首次手术时应尽可能取净髓核组织,对动力位摄片发现有椎问不稳倾向者行后外侧植骨或椎体问植骨融合,常规探查并妥善处理侧隐窝,牵拉神经根时间不应过长且用力轻柔。行腰椎间盘CT和MRI扫描时,应注意包括椎间盘相邻上下椎体的1/3部,以防止遗漏极外侧型椎问盘突出,尽量采用椎板间开窗术式以减少脊柱创伤,术中间断冲洗,术毕持续负压引流,以减少术后黏连,术中应严格无菌操作。  相似文献   
10.
本文选择34颗有银汞充填体悬突的患牙,采用金刚砂钻和银汞磨光钻去除悬突,并观察去除悬突前后部分牙周组织的变化、结果表明银汞充填体悬突危害牙周组织的健康.去除悬突并协同口腔卫生宣教、可促进牙周组织的恢复.  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