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   11155篇
  免费   1005篇
  国内免费   924篇
耳鼻咽喉   88篇
儿科学   154篇
妇产科学   149篇
基础医学   1358篇
口腔科学   137篇
临床医学   1488篇
内科学   1706篇
皮肤病学   139篇
神经病学   597篇
特种医学   458篇
外国民族医学   10篇
外科学   1020篇
综合类   1750篇
现状与发展   4篇
一般理论   1篇
预防医学   789篇
眼科学   470篇
药学   1165篇
  7篇
中国医学   595篇
肿瘤学   999篇
  2024年   30篇
  2023年   155篇
  2022年   430篇
  2021年   548篇
  2020年   389篇
  2019年   372篇
  2018年   409篇
  2017年   336篇
  2016年   345篇
  2015年   488篇
  2014年   607篇
  2013年   548篇
  2012年   824篇
  2011年   936篇
  2010年   635篇
  2009年   456篇
  2008年   654篇
  2007年   577篇
  2006年   537篇
  2005年   567篇
  2004年   354篇
  2003年   309篇
  2002年   265篇
  2001年   229篇
  2000年   290篇
  1999年   281篇
  1998年   204篇
  1997年   176篇
  1996年   168篇
  1995年   129篇
  1994年   123篇
  1993年   75篇
  1992年   76篇
  1991年   74篇
  1990年   76篇
  1989年   59篇
  1988年   61篇
  1987年   49篇
  1986年   38篇
  1985年   36篇
  1984年   20篇
  1983年   13篇
  1982年   13篇
  1981年   18篇
  1980年   14篇
  1978年   8篇
  1977年   12篇
  1976年   15篇
  1973年   9篇
  1970年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The effect of thiopental on glutamate metabolism was studied by 13C magnetic resonance spectroscopy. Cerebral cortical astrocytes were incubated with 0.5 mM [U-13C]glutamate for 2 hr in the presence of 0.5 or 1 mM thiopental. Labeled glutamate, glutamine, aspartate, and glutathione were observed in cell extracts, and glutamine, aspartate, and lactate in the medium. Not only present in the medium was uniformly labeled glutamate, but also glutamate derived from the tricarboxylic acid (TCA) cycle, and thus glutamate release could be detected. The amounts of [U-13C]glutamate and unlabeled glucose taken up by astrocytes were unchanged in the presence of 0.5 mM thiopental and decreased to about 50% and 80%, respectively when the concentration was increased to 1 mM. The amounts of most metabolites synthesized from [U-13C]glutamate were unchanged in the presence of 0.5 mM thiopental, but decreased [U-13C]glutamine, [U-13C]aspartate, and [U-13C]lactate were observed in the 1 mM group. Surprisingly, the amounts of [1,2,3-13C]glutamate, [2,3-13C]aspartate, and [3,4-13C]aspartate (2nd turn via the TCA cycle) were unchanged. However, this was not the case for [1,2-13C]lactate and [2,3-13C]lactate. Such variations indicate cellular compartmentation, possibly caused by a heterogeneous glutamate concentration within the cells affecting TCA cycle turnover rates differently.  相似文献   
72.
论加速建立现代化中药制造工业的若干制药工程技术问题   总被引:2,自引:1,他引:2  
本文针对我国中药制造工业存在的若干制药工程技术问题 ,首先着重分析了中药制药工程学的领域问题 ,指出其研究的目标和任务 ;其次 ,针对中药制药工程技术及工艺问题 ,分析了中药产品质量达不到稳定均一的原因所在 ;最后详细分析了现有中药粉碎设备、提取设备、制剂设备等中药制药设备的有关技术问题。在此基础上 ,指出了中药制造工业和国外存在的差距 ,建议加快推广先进适用的高新技术 ,优先研发中药制药过程全程质量控制技术及中药工业集成制造技术 ,以推动中药制造工业的技术进步。  相似文献   
73.
From 1995 to 1998, 12 burned patients with acute renal failure (ARF) were treated by veno-venous continuous renal replacement therapy (CRRT) at the Burn Unit of H?tel-Dieu de Montréal. Their mean (+/-SD) age was 51+/-12 years, and the mean burned surface covered 48.6+/-15.8% of total body surface area. All patients were mechanically ventilated and presented evidence of sepsis. The mean delay before occurrence of ARF was 15+/-6 days and ARF was mainly related to sepsis and hypotension. Main reasons for CRRT initiation were azotemia and fluid overload. A total of 15 CRRT modalities were applied (12 continuous veno-venous hemodiafiltration, CVVHDF; two continuous veno-venous hemofiltration, CVVH; and one continuous veno-venous hemodialysis, CVVHD) over 14+/-13 days. For CRRT, nine patients received heparin and three were not anticoagulated. Mean values for dialysate and reinjection flow rates were 1134+/-250 ml/h and 635+/-327 ml/h, respectively. Admission weight was 78.8+/-12.7 kg with a mean weight gain before CRRT initiation of 10.0+/-5.8 kg and a mean weight loss during CRRT of 8.9+/-5.5 kg. Nine patients received enteral plus parenteral nutrition, and three, parenteral nutrition only; the total caloric intake was 31.5+/-7.0 kcal/kg/day and protein intake, 1.8+/-0.4 g/kg/day. The normalized protein catabolic rate (nPCR) was evaluated at 2.28+/-0.78 g/kg/day during CRRT. The mortality rate was 50%. The six survivors all recovered normal renal function with four of them requiring intermittent hemodialysis for short periods. In conclusion, veno-venous CRRT is particularly well suited for this selected population allowing smooth fluid removal and aggressive nutritional support.  相似文献   
74.
目的 :探讨透明质酸 (HA)在正常宫颈上皮及宫颈癌中的表达及其与肿瘤发生发展的关系。方法 :用免疫组化法检测 5 9例宫颈浸润癌、35例宫颈上皮内瘤样病变 (CIN)及11例正常宫颈组织中HA和CD4 4v6的表达。结果 :正常宫颈上皮不表达HA。慢性炎症者上皮底层细胞以及细胞间质表达HA ,随病变加重及CIN发生 ,HA表达增强。癌旁组织的上皮细胞HA呈强阳性表达 ,伴有基质HA强阳性染色。癌细胞HA阳性率为 6 7.2 7% ,与病理类型有关 ,角化癌高表达 ,而腺癌不表达 ,在低分化鳞癌中多见不规则灶性HA阴性区。宫颈鳞癌的肿瘤基质HA表达普遍增强。肿瘤基质的HA表达与CD4 4v6呈正相关。结论 :正常宫颈上皮不表达HA ,但炎症与致瘤因素可促使HA表达 ,HA的代谢失衡可能与宫颈癌的发生及浸润行为有关  相似文献   
75.
OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease.  相似文献   
76.
氯硝安定与安定溶液直肠给药用于惊厥急救的对照研究   总被引:21,自引:1,他引:21  
蒋莉  蔡方成  瞿平 《中华儿科杂志》1998,36(10):591-593
目的以安定为对照,探讨氯硝安定溶液直肠给药对惊厥急救的实用价值。方法在28例儿童中对比观察直肠注入氯硝安定与安定溶液的吸收速度和对脑电活动的影响,并比较两药对大鼠实验性惊厥的疗效。结果氯硝安定与安定溶液均能从直肠迅速吸收,皆于用药5分钟后达有效血浓度,分别于3~8分钟及2~8分钟对脑电活动产生显著影响,明显抑制癫痫样波发放,使美解眠诱发的惊厥致死率从对照组的70%降为0。结论氯硝安定与安定溶液直肠给药,均能作为小儿惊厥抢救的有效措施。  相似文献   
77.
为探讨小儿咽侧间隙肿瘤的临床特征,报告4例小儿咽侧间隙肿瘤患者儿的诊治体会。结合临床提出诊断本病宜通过CT扫描,先确定肿瘤的大小和范围,再选择颈侧径路摘除肿瘤.结果治疗的4例患儿均获得了肯定的结果。并且提示手术中应保护重要的血管和神经。  相似文献   
78.
M Zhou  X Li  L Geng  C Qu  S Peng 《中国中药杂志》1998,23(5):301-3, inside back cover
A test was made on the effect of rotundine on the secretion of gastric acid and pepsin activity in rats. Compared with the control group, rotundine(> or = 17.1 mg/kg) inhibited gastric acid and decreased secretion of gastric juice(P < 0.01), but had no influence on pepsin activity. There was a negative relationship between total acidity and pH of gastric juice (r = -0.9818).  相似文献   
79.
食管癌患者手术后死亡病例回顾和原因分析   总被引:2,自引:1,他引:2  
目的:进一步明确食管癌患者手术死亡率,探讨不同时期食管癌手术死亡的主要原因.方法:回顾性分析我院自1954年1月开展食管外科至2003年12月50年间经外科成功切除食管癌手术2 572例.按年代作统计,将前32年(1954年1月~1985年12月)和后18年(1986年1月~2003年12月)分为A、B两组,并就其术后死亡116例原因进行探讨分析.结果:A组手术死亡44例,死亡率为8.15%(44/540).B组手术死亡72例,死亡率为3.54%(72/2 032).A、B两组死亡原因分析差异不大,最常见的死亡原因是吻合口瘘,其次是呼吸衰竭和呼吸循环衰竭;再次是心肌梗塞.结论:吻合口瘘、呼吸衰竭、呼吸循环衰竭、心血管病变(心肌梗塞心脏骤停)是本组食管癌术后死亡的主要原因.  相似文献   
80.
聚乙二醇4000治疗出口梗阻型便秘的临床疗效观察   总被引:1,自引:0,他引:1  
目的 评价聚乙二醇 4 0 0 0 (PEG 4 0 0 0 )治疗出口梗阻型便秘 (OOC)的临床疗效。方法 采用随机对照试验方法 ,选择OOC 6 9例 ,随机分为治疗组 (36例 )和对照组 (33例 ) ,分别接受PEG 4 0 0 0和乳果糖治疗 ,疗程 4周并评估其疗效。总体疗效评估采用模拟视觉梯度的评分方法 (1 0 0mmVAS)。结果 治疗 2周和 4周后 ,二组每周排便次数较治疗前均显著增加 ,大便性状、排便困难和直肠排空感均也比治疗前明显改善 (P <0 .0 1 ) ,但二组间差异无显著性 (P <0 .0 5 ) ,其中大便性状改善PEG 4 0 0 0明显优于乳果糖 (P <0 .0 5 )。大便性状恢复正常比例治疗组大于对照组 (治疗 2周和 4周后 ,分别为 75 .0 %和 83.3%比 5 1 .5 %和 6 0 .6 % ,P <0 .0 5 )。PEG 4 0 0 0组 1 0 0mmVAS评分为75 .3,显著高于乳果糖组的 5 4 .8(P <0 .0 5 )。结论 聚乙二醇 4 0 0 0治疗出口梗阻型便秘安全有效  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