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   342篇
  免费   25篇
  国内免费   2篇
儿科学   4篇
妇产科学   1篇
基础医学   34篇
口腔科学   11篇
临床医学   20篇
内科学   54篇
皮肤病学   1篇
神经病学   57篇
特种医学   11篇
外国民族医学   1篇
外科学   52篇
综合类   18篇
预防医学   18篇
眼科学   8篇
药学   64篇
肿瘤学   15篇
  2023年   3篇
  2022年   2篇
  2021年   11篇
  2020年   3篇
  2019年   9篇
  2018年   5篇
  2017年   3篇
  2016年   12篇
  2015年   23篇
  2014年   24篇
  2013年   27篇
  2012年   34篇
  2011年   29篇
  2010年   9篇
  2009年   10篇
  2008年   19篇
  2007年   24篇
  2006年   23篇
  2005年   8篇
  2004年   15篇
  2003年   13篇
  2002年   9篇
  2001年   5篇
  2000年   8篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   3篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1985年   4篇
  1983年   2篇
  1980年   1篇
  1978年   1篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1958年   1篇
  1956年   1篇
  1954年   2篇
  1939年   1篇
排序方式: 共有369条查询结果,搜索用时 46 毫秒
1.
17β-雌二醇对大鼠脊髓损伤后神经保护作用的研究   总被引:1,自引:0,他引:1  
目的:探讨17β-雌二醇(E2)对大鼠脊髓损伤(SCI)后的神经保护作用及其机制。方法:应用改良的Allen′s重物打击法建立大鼠急性脊髓损伤模型,将大鼠随机分为两组:A组(PBS对照组)和B组(E2治疗组),每组42只,B组造模成功后15min及24h腹腔注射E2(4.0mg/kg,以PBS溶解),A组在相同时间给予等量无菌PBS。分别于伤后7d、14d、21d及28d,应用改良Tarlov评分法和Rivlin斜板试验评价大鼠脊髓神经功能恢复情况。于伤后6h、24h、3d、7d、14d及28d时处死动物,以损伤部位为中心取材,HE染色观察脊髓组织病理变化,TUNEL法染色检测细胞凋亡,免疫组化染色检测caspase-3、Bcl-2的表达情况。结果:从伤后14d起,B组Tarlov评分和斜板试验角度与A组相比差异有显著性(P〈0.01)。TUNEL法检测表明,大鼠SCI后存在细胞凋亡,3d时达高峰,与caspase-3的表达基本一致,B组伤后24h、3d及7d时凋亡细胞比率显著低于A组(P〈0.01或P〈0.05)。免疫组化结果显示B组伤后24h、3d、7d、14d及28d时caspase-3表达低于A组(P〈0.01或P〈0.05),而Bcl-2表达高于A组(P〈0.01或P〈0.05)。结论:E2能促进大鼠SCI后的神经功能恢复,具有一定的神经保护作用;E2可能是通过减少SCI后继发性细胞凋亡的机制发挥作用的。  相似文献   
2.
BACKGROUND: Elevated cortisol levels might account for the reduction in central serotonin 1A (5-hydroxytryptamine [5-HT](1A)) receptor binding and function observed in patients with major depression. We tested this hypothesis by studying the effect of acute administration of hydrocortisone on 5-HT(1A) receptor binding potential (BP) in subjects recovered from depression. METHODS: We studied 14 subjects (8 male, 6 female) who had recovered from at least two episodes of major depression and had been euthymic and drug free for at least 6 months. Serotonin 1A receptor BP was measured by [(11)C]WAY-100635 in conjunction with positron emission tomography. Subjects were tested on two occasions in a double-blind, random-order, crossover design after administration of either hydrocortisone (100 mg orally) or placebo 12 hours previously. Positron emission tomography scans were analyzed with a region of interest analysis. RESULTS: Hydrocortisone treatment did not decrease 5-HT(1A) receptor BP either in the hippocampus, which was our a priori hypothesis, or in other cortical 5-HT(1A) regions; however, female subjects had a higher 5-HT(1A) receptor BP in certain brain areas compared with male subjects. CONCLUSIONS: These data are consistent with an earlier study in healthy volunteers and do not support the proposal that decreased 5-HT(1A) receptor BP in patients with acute major depression is a consequence of cortisol hypersecretion.  相似文献   
3.
One hundred sixty-eight adult siblings and parents from affected and control families were tested for ERP characteristics using two tasks involving an auditory oddball paradigm. Significant within family differences among affected families suggest that risk for developing alcoholism may be seen even in adult subjects who have had experience consuming alcohol. Further, analysis of quantity and recency of drinking in the past seven days were not correlated with either amplitude or latency of P300, suggesting that the within-family differences observed reflect relative risk for developing alcoholism rather than experience with alcohol.  相似文献   
4.
5.
Patricia  Tueting  Samuel  Sutton  Joseph  Zubin 《Psychophysiology》1970,7(3):385-394
A late positive-going component (P3) of the average evoked potential recorded from human scalp was shown to be quantitatively related to a priori stimulus probability both when the S was told the identity of the stimulus before it was presented and when the S was not told, and was instructed to guess. In the guessing situation, the amplitude of P3 was much larger and was influenced not only by the a priori probability of events determined by the experimenter but also by the interaction of these probabilities with the S's guessing behavior. The amplitude of the late positive component was inversely related to the proportion of trials in which a particular event was associated with a particular guess, i.e., the proportion of hits and misses. It was larger the more unexpected the outcome of the guess. This relationship held for different methods of manipulating the probability of two events.  相似文献   
6.
7.
IntroductionAutosomal recessive polycystic kidney disease (ARPKD) is a rare cause of renal failure with a highly variable clinical course. Patients who are symptomatic early in life frequently require early nephrectomy and peritoneal dialysis. In these patients there are little data to guide clinicians on whether to select unilateral nephrectomy or bilateral nephrectomy at the initial operative intervention. We review our experience with this disease process.MethodsA retrospective review was performed of 11 patients at our institution with ARPKD symptomatic within the first month of life. Charts were reviewed for relevant clinical data, and patients were divided into groups based on undergoing either unilateral or bilateral nephrectomy at their initial intervention. The decision for unilateral versus bilateral nephrectomy was decided by the clinical team without any available guidelines.ResultsOf the 11 patients reviewed, two patients died within the first two weeks from other complications. The remaining 9 all required nephrectomy, with 5 undergoing synchronous bilateral nephrectomy, and 4 undergoing initial unilateral nephrectomy. All four patients required removal of their contralateral kidney, a median of 25.5 days later. There was no difference in mortality, ventilator free days, or time to full feeds between the two groups, although the group undergoing initial unilateral nephrectomy had more TPN days than their counterparts (28 vs 17 days, p = 0.014).ConclusionsIn our cohort, there were few significant differences between the groups based on choice of initial unilateral or bilateral nephrectomy, and all children ultimately required removal of both kidneys. These data suggest that anesthetic exposures and other clinical outcomes might be optimized by initial bilateral nephrectomy.Level of evidenceIII.  相似文献   
8.
While accumulating evidence suggests that effective real-life decision-making depends upon the functioning of the orbitofrontal cortex, much less is known about the involvement of the monoamine neurotransmitter systems and, in particular, serotonin. In the present study, we explored the impact of depleting the serotonin precursor, tryptophan, on human decision-making. Eighteen healthy volunteers consumed an amino-acid drink containing tryptophan and 18 healthy volunteers consumed an amino-acid drink without tryptophan, before choosing between simultaneously presented gambles, differing in the magnitude of expected gains (ie reward), the magnitude of expected losses (ie punishment), and the probabilities with which these outcomes were delivered. Volunteers also chose between gambles probing identified non-nomative biases in human decision-making, namely, risk-aversion when choosing between gains and risk-seeking when choosing between losses. Tryptophan-depleted volunteers showed reduced discrimination between magnitudes of expected gains associated with different choices. There was little evidence that tryptophan depletion was associated with altered discrimination between the magnitudes of expected losses, or altered discrimination between the relative probabilities with which these positive or negative outcomes were delivered. Risk-averse and risk-seeking biases were also unchanged. These results suggest that serotonin mediates decision-making in healthy volunteers by modulating the processing of reward cues, perhaps represented within the orbitofrontal cortex. It is possible that such a change in the cognition mediating human choice is one mechanism associated with the onset and maintenance of anhedonia and lowered mood in psychiatric illness.  相似文献   
9.
目的 探讨反义端粒酶肽核酸 (PNA)片段对肺癌细胞株端粒酶活性及细胞株生长的抑制作用。方法 将人工合成的端粒酶反义PNA片段 ,应用脂质体转染法将反义端粒酶序列导入肺腺癌细胞株A5 49及小细胞癌细胞株NCI H44 6中 ,采用MTT法检测活细胞数 ,采用RT PCR ELLISA法检测端粒酶活性。结果 转染 72h后 ,A5 49、NCI H 44 6细胞株端粒酶活性 (A45 0值 )分别由 0 .5 82± 0 .0 3 9和 0 .5 71± 0 .0 43降低至 0 .2 94± 0 .0 48(P <0 .0 1)和 0 .2 76± 0 .0 5 1(P <0 .0 1) ;而两细胞株的活细胞数 (A5 80值 )分别由 0 .485± 0 .0 0 9和 0 .5 13± 0 .0 15降低至 0 .191± 0 .0 2 7(P <0 .0 1)和 0 .13 8± 0 .0 46(P <0 .0 1) ,细胞生长受到显著抑制。结论 反义端粒酶PNA片段具有抑制肺癌细胞株端粒酶活性的作用 ,并可抑制肺癌细胞的生长  相似文献   
10.
目的 探讨抑郁症患者血清半乳糖凝集素-3(Galectin-3)、神经轴突导向因子-1(Netrin-1)、白介素-33(IL-33)水平表达,分析其与患者认知功能损害的关系.方法 选取2016年1月至2019年12月我科收治的抑郁症患者130例作为研究对象(抑郁症组).同期,另选取我院体检健康志愿者100例(对照组).采用酶联免疫吸附法检测两组血清Galectin-3、Netrin-1、IL-33水平.采用智力状态检查量表(MMSE)评估患者认知功能受损程度.采用多因素Logistic回归分析影响抑郁症患者认知功能损害的危险因素.结果 抑郁症组血清Galectin-3、IL-33水平高于对照组,血清Netrin-1低于对照组,差异有统计学意义(P<0.05).认知障碍组血清Galectin-3、Netrin-1、IL-33、HAMD-17评分和MMSE评分与认知正常组血清Galectin-3、Netrin-1、IL-33、HAMD-17评分和MMSE评分相比,差异有统计学意义(P<0.05).多因素Logistic回归分析显示,血清Galectin-3、IL-33、HAMD-17评分升高和血清Netrin-1降低是影响抑郁症患者认知功能损害的独立危险因素(P<0.05).ROC曲线结果显示,血清Galectin-3、Netrin-1、IL-33及三者联合检测预测患者认知功能损害的AUC分别为0.801、0.788、0.843和0.910.结论 抑郁症患者血清GaIectin-3、IL-33水平升高及Netrin-1水平降低,与患者认知功能损害密切相关,联合检测血清Galectin-3、Netrin-1、IL-33对抑郁症患者认知功能损害的预测价值更高,从而有助于尽早进行预防.  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