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   3413篇
  免费   155篇
  国内免费   34篇
耳鼻咽喉   21篇
儿科学   109篇
妇产科学   54篇
基础医学   687篇
口腔科学   81篇
临床医学   339篇
内科学   401篇
皮肤病学   116篇
神经病学   330篇
特种医学   84篇
外科学   283篇
综合类   241篇
一般理论   1篇
预防医学   340篇
眼科学   66篇
药学   268篇
中国医学   92篇
肿瘤学   89篇
  2023年   23篇
  2022年   44篇
  2021年   130篇
  2020年   91篇
  2019年   223篇
  2018年   191篇
  2017年   149篇
  2016年   102篇
  2015年   76篇
  2014年   148篇
  2013年   206篇
  2012年   146篇
  2011年   162篇
  2010年   123篇
  2009年   126篇
  2008年   130篇
  2007年   130篇
  2006年   117篇
  2005年   89篇
  2004年   76篇
  2003年   68篇
  2002年   61篇
  2001年   55篇
  2000年   51篇
  1999年   48篇
  1998年   26篇
  1997年   30篇
  1996年   19篇
  1995年   27篇
  1994年   27篇
  1993年   17篇
  1992年   33篇
  1991年   22篇
  1990年   27篇
  1989年   21篇
  1988年   14篇
  1987年   16篇
  1986年   17篇
  1985年   62篇
  1984年   87篇
  1983年   49篇
  1982年   64篇
  1981年   72篇
  1980年   39篇
  1979年   46篇
  1978年   32篇
  1977年   24篇
  1976年   20篇
  1975年   17篇
  1973年   9篇
排序方式: 共有3602条查询结果,搜索用时 265 毫秒
41.
Features of paw edema induced by subplantar injection of actinomycin D (act D) were investigated in rats. The paw edema was produced as early as the 1st day and reached a maximal level on the 3rd or the 4th day. Thereafter, it began to subside progressively and was considerably reduced by the 16th day following act D (20 μgm) injection. A direct dose response relationship between the amount of act D injected and the intensity of the paw edema was obtained. No difference in β-glucuronidase and acid phosphatase activity was found between saline and act D-injected paws on the 2nd day. This was followed by an increase in the activity of both enzymes on the 4th, 8th, and 16th days after injection. The histamine content of the saline and act D-injected paws remained unchanged during the early phase of inflammation. A marked increase in the histamine content was noted during the late phase in the drug-injected paw. The effects of act D treatment on capillary permeability to Evans blue dye (EBD) and the edema formation of the paw revealed that a maximal increase in vascular permeability to EBD occurred on the 1st day and was maintained until the 8th day. In contrast to permeability, the paw edema on the 1st day was minimal and increased progressively until the 3rd or 4th day. Thereafter, both the permeability and the paw edema began to diminish and were considerably reduced on the 16th day. Aspirin and hydrocortisone treatment were ineffective in suppressing the act D-induced paw inflammation. Indomethacin produced a somewhat dose-related anti-inflammatory effect against the inflammation caused by this drug.  相似文献   
42.
43.
44.
45.
中药配伍是中医药临床应用的精华之一,合理配伍是保障中药临床用药有效性和安全性的重要措施。配伍后减毒增效机制的研究是诠释中药配伍合理性的关键内容。中药配伍机制研究正处于从体外到体内、成分到靶标、单一技术到多学科融合研究技术的转变历程,因此提出以“体外成分、体内过程、直接靶标”研究为基础,“中药配伍药理机制研究”为目的,从不同角度和不同层面探索中药配伍后作用机制的研究策略。  相似文献   
46.
A microcomputer-based pacemaker system for the evaluation of pacemaker treatment of tachycardia is described. The system may be used to study tachycardia initiation, tachycardia termination or a combination of the two. The software incorporates a visual display unit screen handling package which provides the user-system interface. System-patient interfacing is performed by a separate pacing and sensing unit which communicates with the computer via standard digital input/output lines. Several pacing options are available, selectable from a screen-displayed menu. Each selection also has an associated set of programmable parameters which may be adjusted, within allowed limits, to suit particular studies. Examples of the use of the system for tachycardia termination are given. The main programming language for the controlling software was Fortran IV. Some routines were necessarily written in assembly language. The system is useful for evaluation purposes and forms the basis of a cardiac pacemaker development tool.  相似文献   
47.
Effect of brain and spinal cord injuries on motor imagery   总被引:1,自引:0,他引:1  
Summary The timing of mentally executed movements was measured in ten patients with hemiplegia, tetraplegia and paraplegia. In hemiplegic patients a significant difference in mental duration times was found between the paralysed and the normal represented limb. The paralysed limb was mentally much slower than the healthy one. In contrast, movement times in tetraplegic and paraplegic patients did not differ from those in normal subjects. All patients reported a sensation of subjective effort accompanying the execution of the mental tasks. These observations are compatible with an outflow processing underlying motor imagery.  相似文献   
48.
This article deals with some of the recent evidence bearing on the issues of the liability of benzodiazepines to lead to abuse, dependence, and adverse behavioral effects. Reviews of epidemiological, clinical and experimental literature indicated that the previous conclusion about abuse of these drugs still holds: the vast majority of the use of benzodiazepines is appropriate. Problems of nonmedical use arise nearly exclusively among people who abuse other drugs. Nevertheless, there are reasons for concern about patients who take benzodiazepines regularly for long periods of time. These drugs can produce physiological dependence when taken chronicaly, and although this does not appear to result in dose escalation or other evidence of psychological dependence, physiological dependence can result in patient discomfort if drug use is abruptly discontiniued. Also, physicians are currently prescribing shorter-acting benzodiazepines in preference to longer-acting benzodiazepines. The shorter-acting drugs can produce a more intense withdrawal syndrome following chronic administration. Furthermore, rates of use of benzodiazepines increase with age, and elderly patients are more likely than younger ones to take the drug chronically. The clearest adverse effect of benzodiazepines is impairment of memory. This, too, may be particular concern in older patients whose recall in the absence of drug is typically impaired relative to younger individuals, and who are more compromised following drug administration.This article was supported by USPHS Grant DA-00254 and by funding from Hoffmann-La Roche, Inc.  相似文献   
49.
目的:探讨青少年特发性脊柱侧弯(adolescent idiopathic scoliosis,AIS)胸腰椎生理曲度变化情况以及不同类型侧弯之间胸腰椎生理曲度的差异。方法:自2017年1月至2021年12月回顾性分析305例脊柱全长正侧位X线片的青少年患者,根据有无侧弯分为正常组和侧弯组。正常组179例,男79例,女100例;年龄10~18(12.84±2.10)岁。侧弯组126例,男33例,女93例;年龄10~18(13.92±2.20)岁。观察并比较两组Risser征、胸椎后凸角(thoracic kyphosis,TK)与腰椎前凸角(lumbar lordosis,LL),并分析比较不同性别、不同程度侧弯与不同节段侧弯TK值与LL值。结果:侧弯组在女性比率(P=0.001)、年龄(P<0.001)方面均明显高于正常组;Risser征方面,正常组低级别骨化程度比率明显高于侧弯组(P=0.038)。侧弯组TK值明显小于正常组(P<0.001),而两组LL值比较,差异无统计学意义(P=0.147)。男性与女性之间比较,TK值与LL值差异无统计学意义。轻度侧弯TK值明显大于中度侧弯(P<0.05),但LL值比较,差异无统计学意义(P>0.05)。不同节段侧弯之间TK值与LL值比较,差异均无统计学意义(P>0.05)。结论:胸椎与腰椎生理曲度均与性别无关;AIS患者胸椎生理曲度变小,但是腰椎生理曲度基本不变。轻度AIS患者的胸椎生理曲度大于中度AIS患者,但是腰椎生理曲度在轻中度患者之间几乎无差异,且与正常青少年相似。AIS患者胸腰椎生理曲度变化可能与脊柱前柱相对生长过快有关,其具体机制有待进一步研究。  相似文献   
50.
Evidence for opiate-activated NMDA processes masking opiate analgesia in rats   总被引:19,自引:0,他引:19  
The acute interaction between opioid receptors and N-methyl-D-aspartate (NMDA) receptors on nociception was examined in rats using tail-flick and paw-pressure vocalisation tests. When injected at various times (1 to 6 h) after morphine (5 to 20 mg/kg, i.v.) or fentanyl (4x40 microgram/kg, i.v.), the opioid receptor antagonist naloxone (1 mg/kg, s.c.) not only abolished the opiate-induced increase in nociceptive threshold, but also reduced it below the basal value (hyperalgesia). The noncompetitive NMDA receptor antagonist MK-801 (0.15 or 0.30 mg/kg, s.c.) prevented the naloxone-precipitated hyperalgesia and enhanced the antinociceptive effects of morphine (7.5 mg/kg, i.v.) and fentanyl (4x40 microgram/kg, i.v.). These results indicate that the antinociceptive effects of morphine and fentanyl, two opiate analgesics widely used in humans in the management of pain, are blunted by concomitant NMDA-dependent opposing effects which are only revealed when the predominant antinociceptive effect is sharply blocked by naloxone. This study provides new rationale for beneficial adjunction of NMDA receptor antagonists with opiates for relieving pain by preventing pain facilitatory processes triggered by opiate treatment per se.  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