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   73501篇
  免费   6199篇
  国内免费   5051篇
耳鼻咽喉   706篇
儿科学   948篇
妇产科学   767篇
基础医学   7770篇
口腔科学   1049篇
临床医学   9703篇
内科学   9836篇
皮肤病学   753篇
神经病学   3321篇
特种医学   2623篇
外国民族医学   36篇
外科学   6725篇
综合类   14590篇
现状与发展   16篇
一般理论   5篇
预防医学   5822篇
眼科学   1943篇
药学   8224篇
  86篇
中国医学   4098篇
肿瘤学   5730篇
  2024年   163篇
  2023年   802篇
  2022年   2326篇
  2021年   3156篇
  2020年   2505篇
  2019年   2002篇
  2018年   2111篇
  2017年   2184篇
  2016年   1941篇
  2015年   3227篇
  2014年   4185篇
  2013年   3979篇
  2012年   5853篇
  2011年   6584篇
  2010年   4719篇
  2009年   3916篇
  2008年   4758篇
  2007年   4505篇
  2006年   4328篇
  2005年   3920篇
  2004年   2774篇
  2003年   2516篇
  2002年   2179篇
  2001年   1703篇
  2000年   1457篇
  1999年   1302篇
  1998年   906篇
  1997年   851篇
  1996年   683篇
  1995年   599篇
  1994年   523篇
  1993年   281篇
  1992年   351篇
  1991年   274篇
  1990年   201篇
  1989年   183篇
  1988年   206篇
  1987年   139篇
  1986年   119篇
  1985年   96篇
  1984年   60篇
  1983年   40篇
  1982年   32篇
  1981年   23篇
  1980年   14篇
  1979年   20篇
  1978年   8篇
  1974年   6篇
  1971年   6篇
  1949年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
缺锌对大鼠力竭性游泳前后睾酮和锌水平变化的影响   总被引:5,自引:1,他引:4  
本实验动态观察了缺锌和缺锌后补锌对大鼠力竭性游泳前后辜丸和血清睾酮、锌水平以及游泳能力的影响。结果显示:缺锌造成大鼠游泳能力大大降低,补锌后明显增加。不论安静时还是力竭性游泳后12小时内,缺锌大鼠的血清和辜丸锌含量均显著低于对照和补锌大鼠。与对照和补锌大鼠相比,缺锌大鼠的血清和睾丸酮含量,安静时均较低,力竭性游泳后也呈现不同程度的降低。缺锌还造成大鼠辜丸重量的明显下降。结果表明,锌营养不良将损害运动能力。  相似文献   
22.
Objective: To study the relationship between transaldolase activity, protein expression and testosterone synthesis in Leydig cells of pubertal mice. Methods: Leydig cells were cultured for 2 hours and 8 hours, to the Stimulation Group, hCG was added and to the Controls, only the vehicle. The testosterone concentration was then determined by enzyme-linked immunoadsordent assay (ELISA) and the transaldolase activity and protein expression by Western blot. Results: (1) Both the testosterone concentration and the transaldolase activity in both Stimulation Groups were significantly higher than those in the corresponding Controls (2 h: p<0.05-0.01; 8 h: P<0.001); (2) The ratios of the A isoform, the B isoform and the total transaldolase protein to β-actin between the Stimulation and Control Groups did not differ signifi-cantly. Conclusion: hCG stimulates the transaldolase activity as well as the testosterone synthesis in the Leydig cells of pubertal mice, indicating a positive relationship between them.  相似文献   
23.
The paper describes the prenatal ultrasonographic diagnosis of conjoined syncephalus-craniothoraco-omphalopagus twins at 13 weeks' gestation. The mother, after genetic counseling, decided to interrupt the pregnancy. The fetal karyotype, the maternal serum and amniotic fluid alpha-fetoprotein levels were normal. The diagnosis was confirmed by pathologic examination of the fetus after termination of pregnancy.  相似文献   
24.
In many plants, osmotic stress induces a rapid accumulation of proline through de novo synthesis from glutamate. This response is thought to play a pivotal role in osmotic stress tolerance [Kishor, P. B. K., Hong, Z., Miao, G.-H., Hu, C.-A. A. and Verma, D. P. S. (1995) Plant Physiol. 108, 1387-1394]. During recovery from osmotic stress, accumulated proline is rapidly oxidized to glutamate and the first step of this process is catalyzed by proline oxidase. We have isolated a full-length cDNA from Arabidopsis thaliana, At-POX, which maps to a single locus on chromosome 3 and that encodes a predicted polypeptide of 499 amino acids showing significant similarity with proline oxidase sequences from Drosophila and Saccharomyces cerevisiae (55.5% and 45.1%, respectively). The predicted location of the encoded polypeptide is the inner mitochondrial membrane. RNA gel blot analysis revealed that At-POX mRNA levels declined rapidly upon osmotic stress and this decline preceded proline accumulation. On the other hand, At-POX mRNA levels rapidly increased during recovery. Free proline, exogenously added to plants, was found to be an effective inducer of At-POX expression; indeed, At-POX was highly expressed in flowers and mature seeds where the proline level is higher relative to other organs of Arabidopsis. Our results indicate that stress- and developmentally derived signals interact to determine proline homeostasis in Arabidopsis.  相似文献   
25.
尼卡地平控制性降压对家犬脊髓血流的影响   总被引:2,自引:1,他引:1  
目的 观察尼卡地平控制性降压对家犬脊髓血流的影响。方法 成年杂种犬 6只 ,体重 12 5~ 16kg ,以 2 5 %硫喷妥钠麻醉。股动脉置管监测MAP。以尼卡地平 8μg·kg 1·min 1持续静脉注射控制性降压。以激光多普勒血流仪测定脊髓血流 (SCBF)。结果 降压前MAP为 (12 5 7±10 6 )mmHg ,降压后为 (72 0± 11 2 )mmHg ,平均下降 4 2 8%。降压前SCBF为 (9 80± 1 0 5 )v ,降压后为 (8 0 4± 0 96 )v ,降低幅度为 18%。结论 尼卡地平控制性降压对SCBF影响较小 ,可安全用于脊髓手术。  相似文献   
26.
在-30℃下合成了1.0G~6.0G聚酰胺.胺(PAMAM)树形高分子,并采用核磁共振、元素分析对其进行了表征;采用毛细管电泳对1.0GPAMAM进行了分离。结果表明:在该温度下合成的PAMAM具有较好的结构完整性,而毛细管电泳是一种有效的分离提纯PAMAM树形高分子的方法。  相似文献   
27.
28.
取32只2~3个月的BALB/C小白鼠,随机分为4组,每组8只,第1组为对照组,其余3个组为实验组,实验组小白鼠左腿皮下注射苯0.3ml(15ml/kg体重).注射后分别于24h,48h,72h脱颈处死。观察中毒前、后末梢血象、骨髓细胞、骨髓细胞构成的变化。结果表明,苯中毒时骨髓变化先于末梢血象的变化,骨髓的病变为造血细胞变性、坏死,大量毛细血管扩张、充血,骨髓细胞构成降低,而且骨髓细胞构成中细胞成分降低早于外周血粒细胞减少。  相似文献   
29.
笔者从事临床医疗工作20余年,自拟解毒消肿散治疗因阳热毒邪蕴蒸肌肤所致的多种外科疾患,屡获捷效,现报道如下。方药组成与使用方法蒲公英30g,紫花地丁30g,玄明粉50g,冰片6g,共研细末调和均匀,贮瓶密封备用。使用时,视肿疡面积大小,取适量药粉,用食醋调成糊状,摊敷在病变部位,厚约0.5~0.8cm,用塑料薄膜覆盖,外用胶布固定。药物干燥时,可再用食醋浸湿。每日换药2~3次。本方具有清热解毒、散瘀消肿、消炎止痛的作用。主治痈、疽、疔、疖、乳痈、痄腮、毒虫咬伤、痔瘘、肛裂、无名肿毒等证,凡红肿热痛属阳证、热证、实证者均可应用,阴证、寒证…  相似文献   
30.
An animal model of chronic tympanic membrane perforation.   总被引:6,自引:0,他引:6  
Previous investigations into the healing and reconstruction of tympanic membrane (TM) perforations have involved animal models with acute TM perforations. A problem with the acute TM perforation model is that most acute TM perforations will heal spontaneously, both in animals and human beings. A second inadequacy of acute perforation models is that they are not analogous to the salient problem in human beings: long-standing TM perforation. The ideal animal model must have a TM perforation that is permanent, well-epithelialized, and free from infection. The perforation must also be subtotal to preserve a rim of membrane for experimental manipulations. In the chinchilla, we have identified a hardy animal with a short, wide ear canal and relatively large tympanic membranes. Thermal myringectomy, followed by medial infolding of TM microflaps, has resulted in permanent, subtotal chronic TM perforations in the chinchilla animal model. Of the 19 chinchillas (38 TMs) perforated, chronic subtotal perforations were created in 32 ears, 6 to 8 weeks after the initial procedure (84% success). Persistent infection or TM regeneration despite reperforation was recorded in 6 ears (16%) failure). This model is currently being used to assess various biomembrane scaffolds impregnated with growth-promoting substances in the regeneration of a physiologically sound TM, initially in our animal model and then in human beings. We envision the development of a biomembrane disc impregnated with biorecombinant growth factors that may provide a simple office technique for the repair of chronic, non-infected TM perforations.  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