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   1492篇
  免费   101篇
  国内免费   25篇
儿科学   145篇
妇产科学   14篇
基础医学   139篇
口腔科学   77篇
临床医学   145篇
内科学   342篇
皮肤病学   38篇
神经病学   25篇
特种医学   328篇
外科学   83篇
综合类   21篇
预防医学   66篇
眼科学   16篇
药学   87篇
  1篇
中国医学   1篇
肿瘤学   90篇
  2023年   3篇
  2022年   4篇
  2021年   13篇
  2020年   8篇
  2019年   12篇
  2018年   24篇
  2017年   19篇
  2016年   23篇
  2015年   31篇
  2014年   27篇
  2013年   48篇
  2012年   10篇
  2011年   13篇
  2010年   40篇
  2009年   80篇
  2008年   20篇
  2007年   42篇
  2006年   38篇
  2005年   31篇
  2004年   23篇
  2003年   27篇
  2002年   22篇
  2001年   22篇
  2000年   22篇
  1999年   31篇
  1998年   102篇
  1997年   117篇
  1996年   112篇
  1995年   77篇
  1994年   83篇
  1993年   98篇
  1992年   18篇
  1991年   17篇
  1990年   19篇
  1989年   45篇
  1988年   39篇
  1987年   26篇
  1986年   33篇
  1985年   31篇
  1984年   17篇
  1983年   15篇
  1982年   19篇
  1981年   34篇
  1980年   20篇
  1979年   8篇
  1978年   8篇
  1977年   21篇
  1976年   19篇
  1975年   6篇
  1970年   1篇
排序方式: 共有1618条查询结果,搜索用时 15 毫秒
991.

Background  

Many tuberculosis (TB) patients in Indonesia are diagnosed late. We seek to document patient journeys toward TB diagnosis and treatment and factors that influence health care seeking behavior.  相似文献   
992.
The authors reviewed 49 double-contrast and 27 single-contrast barium-enema examinations (BE) in 71 children with suspected inflammatory bowel disease. The diagnosis was proved in 41 patients, of whom 36 underwent proctoscopy and 5 had advanced disease which was treated surgically within 3 to 30 days after BE; the other 30 children served as controls. BE and proctoscopy were compared with regard to sensitivity (detection of disease) and accuracy (categorization as ulcerative or granulomatous colitis). Sensitivity was 93% for double-contrast and 82% for single-contrast BE. Both detected all cases of advanced disease; in early disease, double-contrast BE detected 91% of cases and single-contrast BE 70%. Colitis was correctly categorized as ulcerative or granulomatous in 93% with double-contrast BE and 86% with single-contrast BE. Specificity within the control group was 100% with both techniques. The authors conclude that both types of BE exhibit similar sensitivity in advanced disease, but the double-contrast technique is more accurate in detecting early disease.  相似文献   
993.
Gated magnetic resonance (MR) imaging was used to evaluate central cardiovascular anatomy in 172 subjects, 31 of whom were healthy volunteers. Using the spin-echo technique, images of diagnostic quality were obtained in 93% of cases with TE = 28 msec and in 65% of cases with TE = 56 msec. Transverse multisection sequences encompassing most of the left ventricle required approximately 6-8 minutes. Corroborative studies were available in 134 of 141 patients who had cardiovascular disease; two dimensional echocardiograms and angiography in 133 and 100 patients, respectively. Gated MR demonstrated the wall thinning and complications caused by prior myocardial infarctions and high signal intensity of the myocardium at the site of acute myocardial infarctions. MR accurately demonstrated anatomic abnormalities owing to hypertrophic and congestive cardiomyopathies, congenital abnormalities of the heart and great vessels, rheumatic heart disease, pulmonary hypertension, and cardiac and paracardiac masses. Depiction of cardiovascular anatomy and pathoanatomy was attained without the use of any contrast media. Consequently, gated MR is an effective technique for cardiac diagnosis. The short time required for tomographic examination of the entire heart using the multisection technique renders this a practical cardiac imaging modality.  相似文献   
994.
995.
化学修饰为小干扰RNA(siRNA)治疗面临的诸多挑战提供了解决方法。此综述考察现有的各种siRNA修饰方法,包括RNA和双链siRNA结构的各个方面。然后考察化学修饰siRNA的应用,重点关注其作用的专一性(消除免疫反应和杂交依赖性的脱靶作用)和转运方法,同时对酶稳定性和效价也进行了讨论。  相似文献   
996.

Background and purpose:

Activation of cannabinoid (CB) receptors decreases nociceptive transmission in inflammatory or neuropathic pain states. However, the effects of CB receptor agonists in post-operative pain remain to be investigated. Here, we characterized the anti-allodynic effects of WIN 55,212-2 (WIN) in a rat model of post-operative pain.

Experimental approach:

WIN 55,212-2 was characterized in radioligand binding and in vitro functional assays at rat and human CB1 and CB2 receptors. Analgesic activity and site(s) of action of WIN were assessed in the skin incision-induced post-operative pain model in rats; receptor specificity was investigated using selective CB1 and CB2 receptor antagonists.

Key results:

WIN 55,212-2 exhibited non-selective affinity and agonist efficacy at human and rat CB1 versus CB2 receptors. Systemic administration of WIN decreased injury-induced mechanical allodynia and these effects were reversed by pretreatment with a CB1 receptor antagonist, but not with a CB2 receptor antagonist, given by systemic, intrathecal and supraspinal routes. In addition, peripheral administration of both CB1 and CB2 antagonists blocked systemic WIN-induced analgesic activity.

Conclusions and implications:

Both CB1 and CB2 receptors were involved in the peripheral anti-allodynic effect of systemic WIN in a pre-clinical model of post-operative pain. In contrast, the centrally mediated anti-allodynic activity of systemic WIN is mostly due to the activation of CB1 but not CB2 receptors at both the spinal cord and brain levels. However, the increased potency of WIN following i.c.v. administration suggests that its main site of action is at CB1 receptors in the brain.British Journal of Pharmacology (2009) 157, 645–655; doi:10.1111/j.1476-5381.2009.00184.x; published online 3 April 2009  相似文献   
997.
目的:探讨含硒制剂诱导金属硫蛋白在对抗阿霉素心脏毒性中的作用,比较无机硒制剂亚硒酸钠与有机硒制剂富硒麦芽。方法:不同时间给小鼠喂予硒制剂后取血分离血清,按常规查GOT和CK活性,按DTNB法测GSH-Px活性;取心、肝、肾组织按Hg-Chelex法测金属硫蛋白()含量并做心脏病理学检查。结果:两种含硒制剂均能减轻阿霉素引起的体重下降,GOT与CK酶升高及心脏病理损害,其中富硒麦芽的效果略优于亚硒酸  相似文献   
998.
Griffith  MJ; Carraway  T; White  GC; Dombrose  FA 《Blood》1983,61(1):111-118
Plasma levels of antithrombin-heparin cofactor, determined by heparin- dependent antithrombin assay, and antithrombin III antigen were measured in 22 members of a large kindred predisposed to venous thrombosis. While 11 members had reduced plasma levels of both antithrombin-heparin cofactor and antithrombin III antigen, the levels of antithrombin-heparin cofactor were always greater than the levels of antithrombin III antigen: 66% (+/- 7%) and 49% (+/- 5%) of normal plasma, respectively. Pooled normal plasma and plasma from one of the affected family members (60% antithrombin-heparin cofactor and 47% antithrombin III antigen) were fractionated by heparin-agarose affinity chromatography. Antithrombin-heparin cofactor, which eluted from heparin-agarose with buffer containing 0.4 M NaCl and did not cross- react with antibody specific for antithrombin III and did not inhibit factor Xa at an appreciable rate in the presence of heparin, was designated heparin cofactor A. Antithrombin-heparin cofactor, which eluted from heparin-agarose with buffer containing 2.0 M NaCl, was functionally and antigenically identified as antithrombin III. The concentrations of heparin cofactor A in normal and patient plasma were similar (4.5 x 10(-7) M), while the concentration of antithrombin III in patient plasma (8.0 x 10(-7) M) was only 50% of normal (1.6 x 10(-6) M). The functional properties of both heparin cofactor A and antithrombin III obtained from patient plasma were normal. From the results of the present study it would appear that the antithrombin- heparin cofactor concentrating measured in patient plasma reflects the combined concentrations of heparin cofactor A and antithrombin III. Since heparin cofactor A does not cross-react with antibody to antithrombin III, the concentration of antithrombin III antigen in patient plasma is thus lower than the concentration of antithrombin- heparin cofactor.  相似文献   
999.
1000.
Candida species (spp) are commensal yeast that can only instigate oral infection (oral candidosis – OC) when there is an underlying predisposing condition in the host. We investigated four controversial topics on OC: (i) How can a microbiological determination of OC be made as Candida spp. are commensal yeasts and not all of them form hyphae or pseudohyphae during infection? (ii) Is median rhomboid glossitis (MRG) a manifestation of candidal infection? (iii) Can candidal infection cause palate papillary hyperplasia (PPH)? (iv) What is the best therapeutic treatment for denture‐associated erythematous stomatitis (DAES)? Results from extensive literature searches, including a systematic review, suggested the following: (i) the diagnosis of OC merely on the basis of the presence of yeasts is an oversimplification of a complex process. No convincing evidence of a single test or method better able to discriminate the transition from candidal saprophytism to pathogenicity has been reported in the literature; (ii–iii) conclusive evidence of a direct aetiopathogenic relationship between MRG and PPH and candidal infection has not been found; and (iv) only limited evidence is available for any DAES treatment, thus making it impossible to make strong therapeutic recommendations.  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