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   264241篇
  免费   24443篇
  国内免费   16576篇
耳鼻咽喉   2453篇
儿科学   2765篇
妇产科学   3993篇
基础医学   33741篇
口腔科学   4899篇
临床医学   34458篇
内科学   41292篇
皮肤病学   3072篇
神经病学   15727篇
特种医学   9737篇
外国民族医学   144篇
外科学   28088篇
综合类   38531篇
现状与发展   56篇
一般理论   24篇
预防医学   15543篇
眼科学   7943篇
药学   26809篇
  192篇
中国医学   12957篇
肿瘤学   22836篇
  2024年   535篇
  2023年   3303篇
  2022年   8009篇
  2021年   11906篇
  2020年   8785篇
  2019年   8033篇
  2018年   8957篇
  2017年   7764篇
  2016年   7330篇
  2015年   11020篇
  2014年   13599篇
  2013年   12058篇
  2012年   17875篇
  2011年   19762篇
  2010年   11584篇
  2009年   9303篇
  2008年   12737篇
  2007年   12821篇
  2006年   12860篇
  2005年   12678篇
  2004年   8264篇
  2003年   7860篇
  2002年   6682篇
  2001年   9091篇
  2000年   9458篇
  1999年   9220篇
  1998年   4709篇
  1997年   4365篇
  1996年   3380篇
  1995年   3082篇
  1994年   2573篇
  1993年   1773篇
  1992年   3657篇
  1991年   3151篇
  1990年   2698篇
  1989年   2459篇
  1988年   2218篇
  1987年   1931篇
  1986年   1672篇
  1985年   1353篇
  1984年   875篇
  1983年   664篇
  1982年   366篇
  1981年   303篇
  1980年   233篇
  1979年   405篇
  1978年   126篇
  1975年   118篇
  1974年   131篇
  1973年   141篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Whole-body inflammation in trauma patients. An autopsy study   总被引:8,自引:0,他引:8  
In a review of autopsy specimens and reports in 35 trauma cases, we found signs of generalized inflammation and tissue damage with increases in organ weights in organs not primarily injured. These abnormalities occurred independent of the time of death and were also found in patients who died of brain injury alone. The most pronounced signs of inflammation and increases in organ weights were found when the adult respiratory distress syndrome, hypovolemic shock, or multiple organ failure were the causes of death. These findings are similar to those found in several organs of rabbits after four hours of complement activation in combination with 20 minutes of hypoxia. Therefore, the autopsy findings in this series of trauma patients might represent the morphologic features of adult respiratory distress syndrome and multiple organ failure in an early, preclinical stage.  相似文献   
993.
竹黄颗粒剂Ⅱ号对应激小鼠皮肤肥大细胞影响的实验研究   总被引:6,自引:0,他引:6  
目的:阐明竹黄颗粒剂Ⅱ号治疗现的作用机制。方法:应用形态学方法观察竹黄Ⅱ号对应激小鼠皮肤肥大细胞的影响。结果:束缚应激诱导小鼠皮肤肥大细胞脱颗粒,竹黄Ⅱ号抑制了此效应。结论:提示竹黄颗粒剂Ⅱ号可抑制心理应激诱导的皮肤肥大细胞脱颗粒,可能是其治疗银屑病的疗效机制之一。  相似文献   
994.
黄连细胞二步法悬浮培养生产黄连生物碱类成分的探索   总被引:6,自引:0,他引:6  
为提高用植物细胞培养生产镒生代谢产物的单位产量,作者对黄连细胞采用二步法悬浮培养生产黄连生物碱进行了探索。结果显示:黄连细胞采用一步法悬浮培养6周,细胞干,鲜重产率分别为20.96g/L和174.92g/L,增重约700%,细胞中总生物碱含量为14.79mg/g.cell dw,培养基中生物碱量为12.96mg/L,每升培养液共可收获生物碱323mg。采用先在生长培养基中培养3周,在合成碱量为12  相似文献   
995.
小儿疳证源流考   总被引:1,自引:0,他引:1  
疳作为一个病名,最早见于隋《诸病源候论》。首先将疳证作为儿科专有疾病者,为宋初《太平圣惠方》。本病分类最全面,收集方剂最丰富当推宋《幼幼新书》。南宋出版的《小儿卫生总微论方》首次将疳证归类为五疳。本草文献中对本病贡献最大的为明《本草纲目》。清《温病条辨》首次将本病治法作全面总结。1994年国家中医药管理局颁布的《中医病证诊断疗效标准》首次以法规的形式将本病作了统一规范  相似文献   
996.
For a prospective study of lead exposure and early development, we recruited pregnant women from a lead smelter town and from an unexposed town in Yugoslavia and followed their children through 7 years of age. In this paper we consider associations between lifetime lead exposure, estimated by the area under the blood lead (BPb) versus time curve (AUC7), and intelligence, with particular concern for identifying lead's behavioral signature. The Wechsler Intelligence Scales for Children-Version III (WISC-III) was administered to 309 7-year-old children, 261 of whom had complete data on intelligence, blood lead, and relevant sociodemographic covariates (i.e., Home Observation for the Measurement of the Environment (HOME), birth weight, gender, sibship size, and maternal age, ethnicity, intelligence, and education). These showed anticipated associations with 7-year intelligence, explaining 41-4% of the variance in Full Scale, Performance, and Verbal IQ. Before covariate adjustment, AUC7 was unrelated to intelligence; after adjustment, AUC7 explained a significant 2.8%-4.2% of the variance in IQ. After adjustment, a change in lifetime BPb from 10 to 30 micro/dl related to an estimated decrease of 4.3 Full Scale IQ points; estimated decreases for Verbal and Performance IQ were 3.4 and 4.5 points, respectively. AUC7 was significantly and negatively related to three WISC-III factor scores: Freedom from Distractibility, Perceptual Organization, and Verbal Comprehension; the association with Perceptual Organization was the strongest. Consistent with previous studies, the IQ/lead association is small relative to more powerful social factors. Findings offer support for lead's behavioral signature; perceptual-motor skills are significantly more sensitive to lead exposure than are the language-related aspects of intelligence.  相似文献   
997.
头孢氨苄缓释片在健康人体内的生物利用度和药物动力学   总被引:2,自引:0,他引:2  
目的:比较头孢氨苄缓释片和普通胶囊的生物利用度和药物动力学。方法:10例健康志愿者分别单剂量口服500mg头孢氨苄缓释片和普通胶囊,血药浓度测定方法为HPLC法。结果:两种剂型体内过程均符合一室开放模型,缓释片的达峰时间(Tmax)为(2.58±0.59)h,峰浓度(Cmax)为(10.08±1.68)μg/ml.吸收速率常数(Ka)为(0.90±0.53)/h,消除速率常数(Ke)为(0.26±0.02)/g,半衰期(T1/2)为(2.67±0.23)h,清除率(Cl)为(6.93±1.71)L/h,分布容积(Vd)为(26.66±6.72)L,药一时曲线下面积(AUC)为(48.31±9.32)μg·h/ml。两种剂型T一C一Ka、Ke、T1/2和Cl均存在显著性差异(P<0.01),Vd、AUC无显著性差异(P>0.05);缓释片的相对生物利用度为(104.90±8.35)%。结论:缓释片的吸收减慢,Tmax推迟,T1/2延长,可减少服药次数,提高药物治疗的顺应性。  相似文献   
998.
999.
葛根对小白鼠免疫功能的影响   总被引:8,自引:1,他引:7  
从免疫学方面探讨中药葛根的强身健体作用。方法 :用 10 0 %葛根水浸出液定期给小鼠灌胃 ,然后检测小鼠抗体产生能力、淋巴细胞转化率、巨噬细胞吞噬的功能。结果 :用药组小白鼠以上免疫学指标均有显著增强作用 ,与对照组相比有非常显著性差异 (P <0 .0 1)。未见有副作用。结论 :口服葛根可明显增强机体免疫功能。  相似文献   
1000.
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   
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