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   38757篇
  免费   3609篇
  国内免费   2220篇
耳鼻咽喉   340篇
儿科学   617篇
妇产科学   379篇
基础医学   4147篇
口腔科学   713篇
临床医学   4777篇
内科学   5103篇
皮肤病学   529篇
神经病学   1692篇
特种医学   1533篇
外国民族医学   7篇
外科学   3367篇
综合类   7224篇
现状与发展   11篇
一般理论   2篇
预防医学   3581篇
眼科学   670篇
药学   4512篇
  36篇
中国医学   2707篇
肿瘤学   2639篇
  2024年   141篇
  2023年   499篇
  2022年   1295篇
  2021年   1776篇
  2020年   1348篇
  2019年   1113篇
  2018年   1175篇
  2017年   1218篇
  2016年   1178篇
  2015年   1814篇
  2014年   2220篇
  2013年   2478篇
  2012年   3411篇
  2011年   3664篇
  2010年   2674篇
  2009年   2142篇
  2008年   2506篇
  2007年   2470篇
  2006年   2172篇
  2005年   1893篇
  2004年   1466篇
  2003年   1425篇
  2002年   1203篇
  2001年   892篇
  2000年   662篇
  1999年   427篇
  1998年   242篇
  1997年   210篇
  1996年   154篇
  1995年   136篇
  1994年   119篇
  1993年   72篇
  1992年   85篇
  1991年   68篇
  1990年   45篇
  1989年   38篇
  1988年   26篇
  1987年   23篇
  1986年   17篇
  1985年   10篇
  1984年   8篇
  1983年   7篇
  1981年   4篇
  1979年   21篇
  1978年   3篇
  1977年   3篇
  1976年   4篇
  1970年   4篇
  1969年   6篇
  1968年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Effector memory T cells (TM) play a key role in the pathology of certain autoimmune disorders. The activity of effector TM cells is under the control of Kv1.3 ion channels, which facilitate the Ca2+ influx necessary for T cell activation and function, i.e. cytokine release and proliferation. Consequently, the knock-down of Kv1.3 expression in effector TM's may be utilized as a therapy for the treatment of autoimmune diseases. In this study we synthesized lipid unilamellar nanoparticles (NPs) that can selectively deliver Kv1.3 siRNAs into TM cells in vitro. NPs made from a mixture of phosphatidylcholine, pegylated/biotinylated phosphoethanolamine and cholesterol were functionalized with biotinylated-CD45RO (cell surface marker of TM's) antibodies via fluorophore-conjugated streptavidin (CD45RO-NPs). Incubation of T cells with CD45RO-NPs resulted into the selective attachment and endocytosis of the NPs into TM's. Furthermore, the siRNA against Kv1.3, encapsulated into the CD45RO-NPs, was released into the cytosol. Consequently, the expression of Kv1.3 channels decreased significantly in TM's, which led to a remarkable decrease in Ca2+ influx. Our results can form the basis of an innovative therapeutic approach in autoimmunity.  相似文献   
942.
Pre‐S mutation of hepatitis B virus (HBV) is known to be a risk factor for hepatocarcinogenesis. A previous study suggested that pre‐S mutation(s) may associate with increased recurrence after surgical resection. In the present study, 64 patients with HBV‐related hepatocellular carcinoma (HCC) were categorized into two groups according to the presence or absence of pre‐S mutation(s). The clinicopathological variables of the two groups were analyzed to assess the relationship between pre‐S mutations and postoperative recurrence. Nineteen patients (29.7%) had pre‐S mutations;13 had a pre‐S deletion, three had a pre‐S2 start codon mutation, two patients had both a pre‐S deletion, and a pre‐S2 start codon mutation, and one patient had a pre‐S2 insertion. The two groups did not differ in terms of baseline clinicopathological parameters. Cirrhosis and satellite lesion(s) were predictive factors for postoperative recurrence and poor overall survival. Recurrence‐free survival (P = 0.320) and overall survival (P = 0.238) did not differ significantly when pre‐S mutations were present. In conclusion, this study did not find evidence supporting the notion that pre‐S mutation(s) are associated with postoperative recurrence after surgical resection. J. Med. Virol. 85:589–596, 2013. © 2013 Wiley Periodicals, Inc.  相似文献   
943.
944.
Recent studies have suggested that the right inferior frontal gyrus (rIFG) may be involved in pain‐related empathy. To verify the role of the rIFG, we performed a functional magnetic resonance imaging (fMRI) experiment to replicate previous research and further designed a noninvasive repetitive transcranial magnetic stimulation (rTMS) experiment to probe the causal role of the rIFG in pain‐related empathy processing. We assigned 74 volunteers (37 females) to three groups. Group 1 (n = 26) performed a task in which participants were required to perceive pain in others (task of pain: TP) and we used fMRI to observe the activity of the rIFG during pain‐related empathy processing. Then, we applied online rTMS to the rIFG and the vertex site (as reference site) to observe the performance of Group 2 (n = 24; performing TP) and Group 3 (n = 24; performing a control task of identifying body parts; task of body: TB). fMRI experiment demonstrated stronger activation in the rIFG than in the vertex during the perception of pain in others (p < .0001, Bonferroni‐corrected). rTMS experiment indicated that when the rIFG was temporarily disrupted, participants perceived pain in others significantly more slowly (p < .0001, Bonferroni‐corrected) than when the vertex was disrupted. Our results provide evidence that the rIFG is involved in pain‐related empathy processing, which yields insights into how the brain perceives pain in others.  相似文献   
945.
目的 对比研究经皮椎弓根螺钉内固定术(PPS)与小切口Wiltse入路椎弓根螺钉内固定术(MWPS)治疗胸腰椎骨折的短期临床效果.方法 回顾性分析2018年2月—2020年2月四川省人民医院金牛医院骨一科收治的86例单节段胸腰椎骨折患者的临床资料,根据术式不同分为PPS组(41例)和MWPS组(45例).PPS组男性22例,女性19例;年龄18~70岁,平均48.9岁.致伤原因:高处坠落伤12例,道路交通伤25例,重物砸伤4例.MWPS组男性27例,女性18例;年龄18~70岁,平均49.0岁;致伤原因:高处坠落伤11例,道路交通伤28例,重物砸伤6例.比较两组患者的手术时间、术中出血量、术中透视时间、术后疼痛情况以及术后1个月Cobb角纠正程度、椎体高度恢复程度以及椎体复位情况.结果 MWPS组手术时间和术中透视时间分别为(73.58±5.73)min、(66.36±12.78)s,均明显少于PPS组[(85.74±5.82)min、(312.69±11.92)s],P<0.01;两组术中出血量分别为(68.62±3.63)mL、(69.65±3.72)mL,差异无统计学意义(P>0.05);MWPS组术后24h、7d、14d和1个月视觉模拟评分(VAS)明显低于PPS组[(5.8±0.7)分vs.(6.1±0.6)分、(3.3±0.7)分vs.(4.2±0.8)分、(2.1±0.1)分vs.(2.9±0.3)分、(1.1±0.1)分vs.(1.9±0.2)分],P<0.05;MWPS组置钉准确率和术后椎体复位率明显高于PPS组(91.85%vs.80.49%、88.89%vs.70.73%),P<0.05;MWPS组术后1个月椎体高度恢复程度和术后1个月Cobb角纠正程度均高于PPS组[(98.87±11.57)%vs.(97.58±11.65)%、(85.17±8.63)%vs.(82.91±8.87)%],但差异无统计学意义(P>0.05).结论 PPS与MWPS治疗胸腰椎骨折均具有良好的短期临床效果,但MWPS具有更高的置钉准确率和椎体复位率以及更低的辐射量,更能有效缓解患者术后的疼痛程度.  相似文献   
946.
ObjectiveTo compare the diagnostic performance of contrast-enhanced radial T1-weighted gradient-echo 3-tesla (3T) magnetic resonance imaging (MRI) and computed tomography (CT) for the detection of visceral pleural surface invasion (VPSI). Visceral pleural invasion by non-small-cell lung cancer (NSCLC) can be classified into two types: PL1 (without VPSI), invasion of the elastic layer of the visceral pleura without reaching the visceral pleural surface, and PL2 (with VPSI), full invasion of the visceral pleura.Materials and MethodsThirty-three patients with pathologically confirmed VPSI by NSCLC were retrospectively reviewed. Multidetector CT and contrast-enhanced 3T MRI with a free-breathing radial three-dimensional fat-suppressed volumetric interpolated breath-hold examination (VIBE) pulse sequence were compared in terms of the length of contact, angle of mass margin, and arch distance-to-maximum tumor diameter ratio. Supplemental evaluation of the tumor-pleura interface (smooth versus irregular) could only be performed with MRI (not discernible on CT).ResultsAt the tumor-pleura interface, radial VIBE MRI revealed a smooth margin in 20 of 21 patients without VPSI and an irregular margin in 10 of 12 patients with VPSI, yielding an accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F-score for VPSI detection of 91%, 83%, 95%, 91%, 91%, and 87%, respectively. The McNemar test and receiver operating characteristics curve analysis revealed no significant differences between the diagnostic accuracies of CT and MRI for evaluating the contact length, angle of mass margin, or arch distance-to-maximum tumor diameter ratio as predictors of VPSI.ConclusionThe diagnostic performance of contrast-enhanced radial T1-weighted gradient-echo 3T MRI and CT were equal in terms of the contact length, angle of mass margin, and arch distance-to-maximum tumor diameter ratio. The advantage of MRI is its clear depiction of the tumor-pleura interface margin, facilitating VPSI detection.  相似文献   
947.
Wei  Zhiwen  Dong  Zuxin  Jia  Juan  Liang  Xinhua  Wang  Tao  Hu  Meng  Fu  Shanlin  Yun  Keming 《International journal of legal medicine》2021,135(4):1437-1447
International Journal of Legal Medicine - Organophosphorus pesticides (OPS) are widely used in the world, and many poisoning cases were caused by them. Phorate intoxication is especially common in...  相似文献   
948.

Purpose

Due to their comorbidities, dialysis patients have many chances to undergo radiologic procedures using iodinated contrast media. We aimed to assess time-sequenced blood oxidative stress level after contrast exposure in hemodialysis (HD) patients compared to those in the non-dialysis population.

Materials and Methods

We included 21 anuric HD patients [HD-coronary angiography (CAG) group] and 23 persons with normal renal function (nonHD-CAG group) scheduled for CAG, and assessed 4 oxidative stress markers [advanced oxidation protein products (AOPP); catalase; 8-hydroxydeoxyguanosine; and malondialdehyde] before and after CAG, and subsequently up to 28 days.

Results

In the nonHD-CAG group, only AOPP increased immediately after CAG and returned to baseline within one day. However, in the HD-CAG group, all four oxidative stress markers were significantly increased starting one day after CAG, and remained elevated longer than those in the nonHD-CAG group. Especially, AOPP level remained elevated for a month after contrast exposure.

Conclusion

Our study showed that iodinated contrast media induces severe and prolonged oxidative stress in HD patients.  相似文献   
949.

Purpose

To investigate the effect of pretreatment with intravenous nicorandil on the incidence of contrast-induced nephropathy (CIN) in patients with renal dysfunction undergoing coronary angiography.

Materials and Methods

This randomized controlled multicenter study enrolled a total of 166 patients (nicorandil n=81; control n=85) with an estimated glomerular filtration rate <60 mL/min. Nicorandil 12 mg dissolved in 100 mL of 0.9% saline was administered intravenously for 30 minutes just prior to coronary angiography in the nicorandil group. The same volume of only saline was given to the control group. The primary end-point was the incidence of CIN, defined as >0.5 mg/dL increase or >25% rise in serum creatinine (SCr) concentration within 48 hours of contrast exposure compared to baseline.

Results

The final analysis included 149 patients (nicorandil n=73; control n=76). The baseline characteristics and the total volume of the used contrast (Iodixanol, 125.6±69.1 mL vs. 126.9±74.6 mL, p=0.916) were similar between the two groups. The incidence of CIN also did not differ between the nicorandil and control groups (6.8% vs. 6.6%, p=0.794). There was no difference between the two groups in the relative change in SCr from baseline to peak level within 48 hours after coronary angiography (-1.58±24.07% vs. 0.96±17.49%, p=0.464), although the nicorandil group showed less absolute change in SCr than the control group (-0.01±0.43 mg/mL vs. 0.02±0.31 mg/mL, p=0.005).

Conclusion

Prophylactic intravenous infusion of nicorandil did not decrease the incidence of CIN in patients with renal dysfunction undergoing coronary angiography.  相似文献   
950.
Subclavian steal syndrome caused by an acute thrombus is very rare. We present a case of cerebellar infarction with proximal subclavian artery thrombosis. A 56-year-old woman was admitted for sudden vertigo. One day prior to admission, she received a shoulder massage comprised of chiropractic manipulation. On examination, her left hand was pale and radial pulses were absent. Blood pressure was weak in the left arm. Downbeat nystagmus and a right falling tendency were observed. Brain MRI showed multiple acute infarctions in the left cerebellum. The findings of Doppler ultrasonography in the left vertebral artery were compatible with a partial subclavian artery steal phenomenon. Digital subtraction angiography demonstrated a large thrombus in the left subclavian artery. After heparin infusion, thrombus size markedly decreased. Cerebellar infarction caused by acute subclavian thrombosis following minor trauma is rare, but the thrombus can be successfully resolved with anticoagulation.  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