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   33733篇
  免费   2500篇
  国内免费   1102篇
耳鼻咽喉   371篇
儿科学   415篇
妇产科学   373篇
基础医学   5191篇
口腔科学   518篇
临床医学   3470篇
内科学   5356篇
皮肤病学   857篇
神经病学   2441篇
特种医学   1623篇
外国民族医学   5篇
外科学   3861篇
综合类   2665篇
现状与发展   8篇
一般理论   9篇
预防医学   1825篇
眼科学   851篇
药学   3556篇
  17篇
中国医学   1187篇
肿瘤学   2736篇
  2024年   45篇
  2023年   359篇
  2022年   804篇
  2021年   1549篇
  2020年   892篇
  2019年   968篇
  2018年   1101篇
  2017年   886篇
  2016年   1110篇
  2015年   1563篇
  2014年   1895篇
  2013年   2035篇
  2012年   2899篇
  2011年   3010篇
  2010年   1765篇
  2009年   1465篇
  2008年   2035篇
  2007年   1926篇
  2006年   1719篇
  2005年   1612篇
  2004年   1262篇
  2003年   1084篇
  2002年   914篇
  2001年   726篇
  2000年   758篇
  1999年   614篇
  1998年   286篇
  1997年   246篇
  1996年   183篇
  1995年   171篇
  1994年   139篇
  1993年   108篇
  1992年   166篇
  1991年   174篇
  1990年   140篇
  1989年   109篇
  1988年   89篇
  1987年   85篇
  1986年   75篇
  1985年   50篇
  1984年   35篇
  1983年   37篇
  1982年   31篇
  1981年   24篇
  1980年   22篇
  1979年   31篇
  1978年   18篇
  1977年   16篇
  1976年   13篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的:探讨水通道蛋白-4(aquaporin-4,AQP4)在慢性脑缺血后的表达变化及其可能作用。方法:将40只SD大鼠随机分为对照组(N组,10只)和实验组(30只);实验组根据脑缺血时长,分为慢性脑缺血2周组(2W组)、1月龄组(1M组)和2月龄组(2M组),每组各10只。采用双侧颈总动脉永久结扎法(2-VO),构建大鼠慢性脑缺血模型。干湿重法检测大鼠脑含水量,苏木精-伊红染色法观察大鼠脑组织形态学的变化,尼氏染色法观察细胞凋亡情况。免疫荧光法检测AQP4的表达水平和分布情况,免疫印迹法测定AQP4蛋白的相对表达量。免疫荧光检测AQP4与小胶质细胞/巨噬细胞特异性蛋白抗体(ionized calcium binding adapter molecule 1,IBA1)(小胶质细胞的标志物)表达情况。结果:大鼠慢性脑缺血组脑含水量(77.778±0.042,77.813±0.142,77.805±0.027)与对照组(77.786±0.029)相比,无统计学差异(F=0.136,P=0.936),且慢性脑缺血各组之间亦无统计学差异。苏木精-伊红染色和尼氏染色结果显示:与对照组相比,慢性脑缺血组脑组织细胞排列紊乱,部分细胞核固缩、消失,尼氏体数量减少。免疫荧光结果显示,慢性脑缺血组大鼠脑组织较对照组AQP4表达增强(前额叶:F=1 089.311,P=0.000,N组:90.000±1.000,2W组:166.722±3.660,1M组:200.347±0.284,2M组:229.333±5.033;顶叶:F=784.332,P=0.000,N组:171.512±1.340,2W组:215.107±1.817,1M组:223.014±2.080,2M组:232.654±1.319),小胶质细胞活化增生,且部分AQP4与IBA1共标(前额叶:F=182.218,P=0.000,N组:0.718±0.012,2W组:0.822±0.000,1M组:0.907±0.016,2M组:0.970±0.020;顶叶:F=785.416,P=0.000,N组:0.861±0.009,2W组:0.912±0.005,1M组:0.966±0.003,2M组:0.751±0.003);免疫印迹法结果显示,慢性脑缺血组大鼠脑组织AQP4的表达水平上调,并且随缺血时间延长,其表达进一步增强(前额叶:F=587.102,P=0.000,N组:0.589±0.026,2W组:0.938±0.028,1M组:1.185±0.011,2M组:1.515±0.060;顶叶:F=86.881,P=0.000,N组:0.663±0.073,2W组:0.865±0.044,1M组:1.228±0.082,2M组:1.282±0.047)。结论:慢性脑缺血后,由于缺血缺氧导致神经元凋亡、小胶质细胞活化增生和AQP4表达上调,上调的AQP4可能参与了慢性脑缺血后的相关炎症过程。  相似文献   
992.
目的探索对老年重度烧伤合并糖尿病患者实施护理产生的临床效果。方法在该院筛选出68例老年重度烧伤合并糖尿病患者,时间选为2016年5月—2018年5月,使用抽签法对68例患者进行分组,各34例。实施一般护理为对照组,在一般护理基础上实施优化护理为实验组,观察两组产生的护理效果,并对护理后老年日后生活质量进行评估。结果对比两组护理总有效率,实验组高于对照组,差异有统计学意义(P<0.05);对两组护理前后生活质量进行分析,护理前两组数据差异无统计学意义(P>0.05),护理后两组都有显著改善,但实验组优于对照组,差异有统计学意义(P<0.05)。结论对老年重度烧伤并糖尿病患者实施优化护理临床效果更佳,可以促进其早日恢复,提升了日后生活质量,值得临床推广与应用。  相似文献   
993.
994.
TRK‐100STP, a sustained‐release preparation of the orally active prostacyclin analogue beraprost sodium, targets renal hypoxia. This study aimed to show the superiority of TRK‐100STP over placebos in patients with chronic kidney disease (with either primary glomerular disease or nephrosclerosis) to determine the recommended dose. CASSIOPEIR (Chronic Renal Failure Asian Study with Oral PGI2 Derivative for Evaluating Improvement of Renal Function) was a randomized, double‐blind, placebo‐controlled study conducted at 160 sites in seven Asia‐Pacific countries and regions. Eligible patients (n = 892) were randomized to TRK‐100STP 120, 240 μg, or placebo for a treatment period of up to 4 years. The primary efficacy endpoint was time to first occurrence of a renal composite: doubling of serum creatinine or occurrence of end‐stage renal disease. No significant differences were observed in composite endpoints between TRK‐100STP and placebo (P = 0.5674). Hazard ratios (95% CI) in the TRK‐100STP 120 and 240 μg vs. placebo groups were 0.98 (0.78, 1.22) and 0.91 (0.72, 1.14), respectively. The overall incidence of adverse events and adverse drug reactions was comparable between treatment arms.  相似文献   
995.
996.
997.
998.
This study investigated the effects of a low‐frequency home‐based incontinence therapy device on quality of life (QoL) and urinary symptoms in women with urinary incontinence. From May 2017 to February 2018, 34 patients, aged ≥ 20 years, with involuntary urine leakage >2 times/week, were recruited to this study. Patients with severe pelvic organ prolapse, pregnancy, virgin status, and psychological problems were excluded. The incontinence home‐care device treatments were administered in 12‐minute sessions, twice daily for 8 weeks. Simultaneously, hyperthermic conditions of 35°C to 40°C and microvibrations were administered. All patients completed urinary incontinence questionnaires (King's Health Questionnaire [KHQ], Bristol Female Lower Urinary Tract Symptoms [BFLUTS] questionnaire, and the Overactive Bladder Symptom Score [OABSS]) before treatment, as well as 4 and 8 weeks into treatment. Changes in the questionnaire responses over time were compared. Two participants dropped out of the study and there was one screening failure, leaving 31 patients for analysis. After 4 weeks treatment, there were significant improvements in symptoms, such as role limitation, physical limitation, social limitation, personal relationship, emotion, sleep/energy, and severity measures. After 8 weeks treatment, almost all parameters on the KHQ revealed symptomatic improvement. On the BFLUTS, voiding times during activity, nocturia, urgency, urge incontinence, incontinence frequency, stress incontinence, volume leakage, strain to start, intermittency, reduced stream, acute retention, incomplete emptying, and stopping flow showed significant improvements. On the OABSS, almost all storage symptoms improved. Low‐frequency electrical stimulation devices were effective at improving urinary incontinence, which became evident as the duration of treatment increased. Improvement of urgency and frequency was more evident after treatment.  相似文献   
999.
1000.

Background and objectives

The Statewide Sharing variance to the national kidney allocation policy allocates kidneys not used within the procuring donor service area (DSA), first within the state, before the kidneys are offered regionally and nationally. Tennessee and Florida implemented this variance. Known geographic differences exist between the 58 DSAs, in direct violation of the Final Rule stipulated by the US Department of Health and Human Services. This study examined the effect of Statewide Sharing on geographic allocation disparity over time between DSAs within Tennessee and Florida and compared them with geographic disparity between the DSAs within a state for all states with more than one DSA (California, New York, North Carolina, Ohio, Pennsylvania, Texas, and Wisconsin).

Design, setting, participants, & measurements

A retrospective analysis from 1987 to 2009 was conducted using Organ Procurement and Transplant Network data. Five previously used indicators for geographic allocation disparity were applied: deceased-donor kidney transplant rates, waiting time to transplantation, cumulative dialysis time at transplantation, 5-year graft survival, and cold ischemic time.

Results

Transplant rates, waiting time, dialysis time, and graft survival varied greatly between deceased-donor kidney recipients in DSAs in all states in 1987. After implementation of Statewide Sharing in 1992, disparity indicators decreased by 41%, 36%, 31%, and 9%, respectively, in Tennessee and by 28%, 62%, 34%, and 19%, respectively in Florida, such that the geographic allocation disparity in Tennessee and Florida almost completely disappeared. Statewide kidney allocations incurred 7.5 and 5 fewer hours of cold ischemic time in Tennessee and Florida, respectively. Geographic disparity between DSAs in all the other states worsened or improved to a lesser degree.

Conclusions

As sweeping changes to the kidney allocation system are being discussed to alleviate geographic disparity—changes that are untested run the risk of unintended consequences—more limited changes, such as Statewide Sharing, should be further studied and considered.  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