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   52115篇
  免费   3386篇
  国内免费   2834篇
耳鼻咽喉   75篇
儿科学   905篇
妇产科学   325篇
基础医学   3818篇
口腔科学   139篇
临床医学   6685篇
内科学   5824篇
皮肤病学   56篇
神经病学   10964篇
特种医学   2576篇
外国民族医学   1篇
外科学   4096篇
综合类   11303篇
现状与发展   1篇
预防医学   1374篇
眼科学   331篇
药学   5273篇
  57篇
中国医学   4224篇
肿瘤学   308篇
  2024年   38篇
  2023年   436篇
  2022年   776篇
  2021年   1382篇
  2020年   1436篇
  2019年   1146篇
  2018年   1197篇
  2017年   1513篇
  2016年   1696篇
  2015年   1711篇
  2014年   3108篇
  2013年   3165篇
  2012年   3063篇
  2011年   3316篇
  2010年   2876篇
  2009年   2648篇
  2008年   2842篇
  2007年   2909篇
  2006年   2788篇
  2005年   2485篇
  2004年   2192篇
  2003年   2079篇
  2002年   1806篇
  2001年   1603篇
  2000年   1399篇
  1999年   1178篇
  1998年   918篇
  1997年   870篇
  1996年   646篇
  1995年   630篇
  1994年   579篇
  1993年   449篇
  1992年   421篇
  1991年   421篇
  1990年   324篇
  1989年   255篇
  1988年   238篇
  1987年   205篇
  1986年   194篇
  1985年   262篇
  1984年   207篇
  1983年   145篇
  1982年   160篇
  1981年   182篇
  1980年   125篇
  1979年   88篇
  1978年   60篇
  1977年   55篇
  1976年   41篇
  1975年   21篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
目的 探讨双侧深低温停循环(Deep hypothermia and circulatory arrest,DHCA)+顺行性脑灌注(Anterograde cerebral perfusion,ACP)对主动脉弓替换术患者脑损伤的影响。方法 选择2018年1月-2020年1月本院实施主动脉弓替换术的DebakeyⅠ型主动脉夹层患者96例,根据不同的脑保护技术将患者分为单侧ACP组和双侧ACP组,各48例; 2组均进行DHCA,单侧ACP组经右侧腋动脉进行单侧ACP,双侧ACP组经右侧腋动脉和左颈总动脉进行双侧ACP。结果 全部患者痊愈出院,出院前CT复查显示主动脉弓和升主动脉的人工血管血流畅通,无人工血管扭曲和造影剂渗漏等状况。双侧ACP组术后短暂性脑损伤发生率为2.08%(1/48),明显低于单侧ACP组的16.67%(8/48)(P<0.05)。双侧ACP组术后苏醒时间为(13.18±3.42)h,明显短于单侧ACP组的(16.98±4.18)h(P<0.05)。体外循环开始后2组血清神经元特异性烯醇化酶(Neuron-specific enolase,NSE)、中枢神经特异性蛋白 100-β亚型(Specific protein 100-β,S100-β)水平均逐渐升高,且在体外循环结束时达到峰值,随后开始降低; 脑灌注5min后双侧ACP组血清NSE,S-100β水平明显低于单侧ACP组(P<0.05)。结论 双侧深低温停循环顺行性脑灌注对主动脉弓替换术患者脑损伤的影响程度更小,其机制可能是通过降低血清NSE,S-100β水平,进而有效保护脑组织。  相似文献   
43.
44.
《临床与病理杂志》2021,(4):928-933
颈内静脉球血氧饱和度(jugular venous bulb oxygen saturation,SjvO2)监测可及早发现脑氧供需的变化,尽早治疗以减轻脑组织的缺血缺氧性损伤。在神经外科手术、体外循环(cardiopulmonary bypass,CPB)和特殊体位手术中应用广泛,与脑组织氧分压(partial oxygen pressure of brain tissue,PbtO2)和近红外光谱对比有其优势,还可用于围手术期生理探索、指导过度通气、综合脑保护和多模式监测等诊治手段。  相似文献   
45.

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   
46.
47.

Objective

To compare perioperative and long-term outcomes in patients undergoing hemiarch and aggressive arch replacement for acute type A aortic dissection (ATAAD).

Methods

From 1996 to 2017, we compared outcomes of hemiarch (n = 322) versus aggressive arch replacements (zones 2 and 3 arch replacement with implantation of 2-4 arch branches, n = 150) in ATAAD. Indications for aggressive arch were arch aneurysm >4 cm or intimal tear in the aortic arch that was not resectable by hemiarch replacement, or dissection of arch branches with malperfusion.

Results

Patients in the aggressive arch group were significantly younger (mean age: 57 vs 61 years old) and had significantly longer hypothermic circulatory arrest, cardiopulmonary bypass, and aortic crossclamp times. There were no significant differences in perioperative outcomes between hemiarch and aggressive arch groups, including 30-day mortality (5.3% vs 7.3%, P = .38) and postoperative stroke rate (7% vs 7%, P = .96). Over 15 years, Kaplan–Meier survival was similar between hemiarch and aggressive arch groups (log-rank P = .55, 10-year survival 70% vs 72%). Given death as a competing factor, incidence rates of reoperation over 15 years (2.1% vs 2.0% per year, P = 1) and 10-year cumulative incidence of reoperation (14% vs 12%, P = .89) for arch and distal aorta pathology were similar between the 2 groups.

Conclusions

Both hemiarch and aggressive arch replacement are appropriate approaches for select patients with ATAAD. Aggressive arch replacement should be considered for an arch aneurysm >4 cm or an intimal tear at the arch unable to be resected by hemiarch replacement, or dissection of the arch branches with malperfusion.  相似文献   
48.
49.
目的探讨左心室舒张功能减低与青年高血压病患者急性脑梗死的相关性。方法收集2014年10月~2018年2月宝鸡市第二中医医院神经内科收治的青年急性脑梗死同时患有高血压病的患者92例(观察组),同时选取同期患有高血压病的青年体检患者98例(对照组)。对两组患者都进行心脏彩色多普勒检查,观察患者的左心室舒张功能,并分析左心室舒张功能减低与急性脑梗死的关系。结果 190例青年高血压病患者中,左心室舒张功能正常者18例,占9. 47%,左心室舒张功能减低者172例,占90. 53%,其中127例为左心室舒张功能减低1级,占66. 84%(127/190),55例为左心室舒张功能2级,占28. 95%(55/190),8例为左心室舒张功能3级,占4. 21%(8/190)。观察组患者IVRT、Ea/Aa及A’值分别为(114. 97±10. 16)、(0. 79±0. 11)和(5. 21±1. 03),对照组分别为(72. 86±8. 75)、(1. 3±0. 25)和(5. 02±0. 82),差异有统计学意义(P 0. 05)。观察组患者左心室舒张功能减低IVRT、Ea/Aa及A’值和急性脑梗死发生之间有相关关系(r=0. 53,r=0. 61,r=-0. 59)。结论青年左心室舒张功能减低与高血压病有关,左室舒张功能减低可能是青年高血压病患者罹患急性脑梗死的独立预测因素。  相似文献   
50.

Purpose

Although current Delphi Consensus guidelines do not recommend a specific definition of biochemical recurrence after partial gland therapy, these guidelines acknowledge that serial prostate-specific antigen (PSA) tests remain the best marker for monitoring disease after treatment. The purpose of this study was to determine whether PSA velocity at failure per the Phoenix (nadir + 2 ng/mL) definition is associated with metastasis and prostate cancer-specific mortality (PCSM) in a cohort of patients who experienced PSA failure after partial gland therapy.

Methods

Between 1997 and 2007, 285 patients with favorable risk prostate cancer underwent partial prostate brachytherapy to the peripheral zone. PSA velocity was calculated for 94 patients who experienced PSA failure per the Phoenix (nadir + 2) definition. Fine and Gray competing risks regression was performed to determine whether PSA velocity and other clinical factors were associated with metastasis and PCSM.

Results

The median time to PSA failure was 4.2 years (interquartile range: 2.2, 7.9), and the median followup time after PSA failure was 6.5 years (3.5–9.7). Seventeen patients developed metastases, and five experienced PCSM. On multivariate analysis, PSA velocity ≥3.0 ng/mL/year (adjusted hazard ratio 5.97; [2.57, 13.90]; p < 0.001) and PSA nadir (adjusted hazard ratio 0.39; [0.24, 0.64]; p < 0.001) were significantly associated with metastasis. PSA velocity ≥3.0 ng/mL/year was also associated with PCSM (HR 15.3; [1.8, 128.0]; p = 0.012) on univariate analysis.

Conclusions

Rapid PSA velocity at PSA failure after partial gland treatment may be prognostic for long-term outcomes.  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