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   7666篇
  免费   926篇
  国内免费   137篇
耳鼻咽喉   42篇
儿科学   109篇
妇产科学   60篇
基础医学   749篇
口腔科学   67篇
临床医学   942篇
内科学   746篇
皮肤病学   29篇
神经病学   1626篇
特种医学   489篇
外科学   362篇
综合类   1248篇
一般理论   2篇
预防医学   794篇
眼科学   62篇
药学   679篇
  8篇
中国医学   581篇
肿瘤学   134篇
  2024年   12篇
  2023年   114篇
  2022年   206篇
  2021年   413篇
  2020年   392篇
  2019年   351篇
  2018年   312篇
  2017年   346篇
  2016年   333篇
  2015年   366篇
  2014年   613篇
  2013年   551篇
  2012年   499篇
  2011年   532篇
  2010年   393篇
  2009年   386篇
  2008年   335篇
  2007年   321篇
  2006年   308篇
  2005年   248篇
  2004年   202篇
  2003年   196篇
  2002年   160篇
  2001年   118篇
  2000年   91篇
  1999年   93篇
  1998年   60篇
  1997年   71篇
  1996年   44篇
  1995年   55篇
  1994年   59篇
  1993年   53篇
  1992年   37篇
  1991年   46篇
  1990年   56篇
  1989年   36篇
  1988年   30篇
  1987年   27篇
  1986年   29篇
  1985年   37篇
  1984年   37篇
  1983年   15篇
  1982年   22篇
  1981年   17篇
  1980年   25篇
  1979年   14篇
  1978年   16篇
  1977年   22篇
  1975年   8篇
  1974年   7篇
排序方式: 共有8729条查询结果,搜索用时 15 毫秒
41.
Investigators often study rats by microCT to investigate the pathogenesis and treatment of skeletal disorders in humans. However, microCT measurements provide information only on bone mineral content and not the solid matrix. CT scans are often carried out on cancellous bone, which contains a significant volume of marrow cells, stroma, water, and fat, and thus the apparent bone mineral density (BMD) does not reflect the mineral density within the matrix, where the mineral crystals are localized. Water- and fat-suppressed solid-state proton projection imaging (WASPI) was utilized in this study to image the solid matrix content (collagen, tightly bound water, and other immobile molecules) of rat femur specimens, and meet the challenges of small sample size and demanding submillimeter resolution. A method is introduced to recover the central region of k-space, which is always lost in the receiver dead time when free induction decays (FIDs) are acquired. With this approach, points near the k-space origin are sampled under a small number of radial projections at reduced gradient strength. The typical scan time for the current WASPI experiments was 2 hr. Proton solid-matrix images of rat femurs with 0.4-mm resolution and 12-mm field of view (FOV) were obtained. This method provides a noninvasive means of studying bone matrix in small animals.  相似文献   
42.
目的通过蛇毒抗高凝状态酶(AHCSE)、氟尿嘧啶(5-FU)对人肝癌细胞BEL-7404(简称7404细胞)、正常LO2肝细胞(简称LO2细胞)作用的比较,研究AHCSE对肝癌的作用以及探讨其可能的作用机制。方法应用光学显微镜、透射电镜、MTT法、TUNEL、FCM等方法观察7404细胞、LO2细胞经过AHCSE、5-FU处理后,细胞形态学、生物化学等方面的变化。结果7404细胞、LO2细胞经过AHCSE、52FU处理后,发生了形态学改变;小剂量AHCSE对7404细胞具有很强的抑制作用,但对LO2细胞几乎无影响;随着剂量的加大,AHCSE对7404细胞抑制率上升不明显,但是出现对LO2细胞的抑制作用。经AHCSE作用后,7404细胞发生了凋亡,凋亡率随AHCSE浓度的增加而增加;与5-FU对7404细胞作用相似,但5-FU对LO2细胞抑制作用明显增强。结论AHCSE、5-FU对BEL-7404细胞均有很强的抑制作用,诱导细胞凋亡是其作用机制之一,AHCSE可能成为一种新的肝癌细胞凋亡的诱导剂。  相似文献   
43.
侯江红教授擅长运用调脾和胃法调治处于亚健康状态的小儿,治疗小儿慢性湿疹,注重从“健脾和胃、消食清热”法入手,每获良效。  相似文献   
44.
目的 观察七氟醚或丙泊酚麻醉时脑状态指数(CSI)的变化.方法 30例腹腔镜手术患者随机均分成七氟醚组(S组)和丙泊酚组(P组).麻醉诱导:S组吸入2%的七氟醚,每隔1分钟增加1%;P组每隔1分钟重复给予15 mg丙泊酚,直至患者意识消失.记录患者诱导期的CSI数值,并对患者的镇静程度采用警觉/镇静评分(OAA/S)标准评分.结果 S组与P组术前CSI基础值差异无统计学意义,随着麻醉的加深,两组的CSI数值均明显下降(P<0.01),至OAA/S 1分时S组与P组的CSI数值较OAA/S 5分时明显下降(P<0.05或P<0.01),S组与P组的CSI与OAA/S的相关系数r分别为0.843和0.812.结论 CSI监测可反映七氟醚或丙泊酚麻醉时的麻醉深度.  相似文献   
45.
The development of combined microwave‐enhanced/parallel synthesis procedures and their application to the deuteriation of organic compounds via examples of solid‐state hydrogenation is reported. Other labelling procedures, such as solution state catalytic dehalogenations, hydrogenations as well as hydrogen isotope exchange reactions also benefit from the combined technology. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
46.
In recent years many studies of unemployment and health haveshown that unemployed persons are in poorer health. However,one question remained unanswered: is the poorer health of theunemployed caused by unemployment Itself (causation hypotheses)or is it a result of selection processes, whereby people inpoor health are more likely to lose their job and less likelyto be re-employed (selection hypothesis)? Findings from a studybased on the longitudinal data of the German Socio-economicPanel (1984–1988, N=5, 516 persons, 18–64 years)are presented. All health indicators (health satisfaction, chronicillness, handicaps in fulfilling daily life tasks, disability)showed poorer outcomes for the unemployed persons, even aftercontrolling for the possible confounding effects of sodo-demographicvariables. Unemployed persons also consulted a physician morefrequently and were hospitalized more often. But longitudinalanalyses (of becoming unemployed and of re-employment) did notlend much support to the causation hypothesis. Instead, a constantlevel of health satisfaction for persons losing their job andfor the re-employed compared to their initial ratings supportedthe selection hypotheses. This means that in the Federal Republicof Germany persons in poorer health are more likely to losetheir jobs and persons in better health are more likely to bere-employed.  相似文献   
47.
HBV血清学标记携带者的传染受许多因素的影响。本研究采用多因素分析方法,定量描述了各种类型HBV血清学标记携带者家庭内传染性及有关因素影响的大小。家中上次HBsAg携带与易感者HBsAg和HBeAg阳转呈正相关。家中上次抗-HBc携带与易感者抗-HBc阳转呈正相关,OR=5.98;但与抗-HBc滴度变化无显著联系。而家中上次抗-HBc携带,HBsAg与抗-HBc同时携带与易感者HBsAg和HBeAg阳转呈负相关。年龄与HBsAg阳转呈负相关;文化水平与易感者抗-HBs阳转亦呈负相关;手术史、注射史与乙肝续发感染正相关。多因素分析对阐明人群中大量HBV血清学标记携带者的动态变化有一定意义。  相似文献   
48.
介绍微电脑促醒仪的基本结构、工作原理、主要技术特点及临床应用等内容。该仪器运用微电脑控制的促醒仪产生电刺激信号,通过射频耦合方式(或直接耦合方式)传递到植物生存状态患者脑干网状结构刺激电极,激活网状激动系统,促使Pcrsistent Vegtative State,PVS患者康复,取得了较好的效果。  相似文献   
49.
老年亚健康状态与中医药保健   总被引:7,自引:0,他引:7  
人体精气充沛,动作不衰为健康的状态。“老年亚健康状态”亦即老人较青年人偏衰的状态,时老年人除体力外,精神心理状态也是一个重要的方面。人类衰老的亚健康状态的进程,实际上就是整体健康状态——五脏气血逐渐降低的过程,其发展与演变有着肝→心→脾→肺→肾的次序递进关系。老年亚健康状态的摄生原则概括起来有:①顺应自然;②精神调摄;③饮食调养;④体育锻炼。部分老年人因其五脏气衰随年龄的增加,可伴有五脏相应的老年性病证,重在调五脏益元气。对于老年调元益气的药物疗法,宜顺其五脏五行、四时生长化收藏之气而调之。  相似文献   
50.
BACKGROUND: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys. In contrast to haemoperfusion, synthetic perfusion media can be standardized and can prevent the initiation of blood-mediated reperfusion reactions. Thus, an additional aim was to determine whether blood could be replaced by synthetic cell-free perfusion solutions. METHODS: Canine kidneys (n = 30) were harvested from donors euthanized in veterinary practices for causes unrelated to the present study. The kidneys were isolated and perfused with autologous blood or cell-free synthetic electrolyte buffer (Tyrode solution). During perfusion, we monitored renal perfusate flow (RPF), glomerular filtration rate (GFR), electrolyte and glucose reabsorption, oxygen consumption and urine concentration. RESULTS: Changes in perfusion medium did not affect the RPF. In contrast, GFR, urine concentration and oxygen consumption were significantly higher, whereas fractional excretion of sodium and glucose were significantly lower in blood- than in Tyrode-perfused kidneys. CONCLUSIONS: This system offers a simple model for studying whole-organ functional alterations after acute renal ischaemia. Renal function indicators were below values reported during in vivo physiological conditions. These functions were better conserved when kidneys were perfused with autologous blood than with Tyrode.  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