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   1821篇
  免费   118篇
  国内免费   23篇
耳鼻咽喉   19篇
儿科学   74篇
妇产科学   21篇
基础医学   331篇
口腔科学   26篇
临床医学   172篇
内科学   356篇
皮肤病学   90篇
神经病学   197篇
特种医学   61篇
外科学   219篇
综合类   6篇
预防医学   104篇
眼科学   16篇
药学   95篇
肿瘤学   175篇
  2023年   14篇
  2022年   23篇
  2021年   48篇
  2020年   26篇
  2019年   31篇
  2018年   52篇
  2017年   27篇
  2016年   41篇
  2015年   44篇
  2014年   50篇
  2013年   73篇
  2012年   125篇
  2011年   139篇
  2010年   90篇
  2009年   86篇
  2008年   134篇
  2007年   112篇
  2006年   138篇
  2005年   96篇
  2004年   100篇
  2003年   89篇
  2002年   85篇
  2001年   24篇
  2000年   24篇
  1999年   27篇
  1998年   22篇
  1997年   13篇
  1996年   13篇
  1995年   11篇
  1994年   16篇
  1993年   13篇
  1992年   19篇
  1991年   15篇
  1990年   11篇
  1989年   12篇
  1988年   10篇
  1987年   9篇
  1986年   9篇
  1985年   7篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   10篇
  1979年   7篇
  1978年   8篇
  1977年   4篇
  1975年   5篇
  1974年   7篇
  1972年   6篇
  1966年   6篇
排序方式: 共有1962条查询结果,搜索用时 31 毫秒
1.
2.

Background  

For patients suffering of recurrent breast cancer within the irradiated breast, generally mastectomy is recommended. The normal tissue tolerance does not permit a second full-dose course of radiotherapy to the entire breast after a second breast-conserving surgery (BCS). A novel option is to treat these patients with partial breast irradiation (PBI). This approach is based on the hypothesis that re-irradiation of a limited volume will be effective and result in an acceptable frequency of side effects. The following report presents a single center experience with intraoperative radiotherapy (IORT) during excision of recurrent breast cancer in the previously irradiated breast.  相似文献   
3.
Thirteen children with acute lymphoblastic leukemia (ALL) were investigated before and during cytotoxic therapy. EEG findings were correlated with the clinical course and the therapy protocol and compared with normal data obtained from 295 healthy children. Frequency analysis of the background activity of the EEG revealed an initial slowing of the background activity prior to therapy and further slowing each time a combination of vincristine (VCR), daunorubicine (DAU) or adriblastine (ADR), prednisone (FRED), and L-asparaginase (L-ASP) was administered. The slowing of the background activity correlated only with the administration of these drugs. DAU, ADR, and FRED are not known to influence the EEG; therefore, VCR and L-ASP remain the primary candidates responsible for the central nervous system alteration.  相似文献   
4.
Circulating monocytes from hypertensive patients show elevated secretion patterns of pro-inflammatory cytokines, an increased expression of adhesion molecules, and an increased adhesion to vascular endothelial cells. We tested the hypothesis that telmisartan, an angiotensin II type 1 (AT(1)) receptor antagonist, reduces the activation of circulating monocytes from hypertensive patients and diminishes the monocyte-endothelial cell adhesion. Monocytes of 20 hypertensive patients and 20 normotensive controls were isolated by density gradient centrifugation and Dynabeads, and the monocyte adhesion to human aortic endothelial cell monolayers was measured by adhesion assays. To characterize monocyte activation we assessed the expression of activity-related cell surface markers that are also involved in monocyte adhesion to endothelial cells, such as CD11a/b and CD54, as well as the chemokine receptors CCR1, CCR2 and CCR5 before and after telmisartan therapy using flow cytometry. Spontaneous adhesion of monocytes from hypertensive patients and the adhesion after stimulation with angiotensin II were significantly increased compared with those in normotensive controls (p<0.05). Treatment of hypertensive patients with the AT(1) receptor antagonist telmisartan significantly diminished the adhesion of circulating monocytes to human endothelial cells (p=0.02) despite the increase in the expressions of CD11b, CD54 and CCR5 after telmisartan therapy. Reducing monocyte adhesion may be a novel beneficial effect of the AT(1) receptor antagonist telmisartan helping to prevent vascular alterations in hypertension. The mechanism of action remains to be elucidated, since reduction in monocyte adhesion was not attributable to changes in adhesion molecule expression.  相似文献   
5.
Cyclic nucleotides are important second messengers that mediate a number of cellular responses to external signals. Cyclic nucleotide phosphodiesterases play a role in signal transduction by regulating the cellular concentrations of these messengers. Here, we have applied Southern analyses of somatic cell hybrid lines and of recombinant inbred (RI) mouse strains as well as fluorescence chromosomal in situ hybridization (FISH) to chromosomally localize five cAMP-specific nucleotide phosphodiesterase genes in human and mouse. GenesDPDE1, DPDE2, DPDE3, andDPDE4 that share sequence homology with theDrosophila dunce gene were assigned to human chromosomes 19 (DPDE1 andDPDE2), 5q12 (DPDE3), and 1p31 (DPDE4) and to mouse chromosomes 8, 9, 13, and 4, respectively. The high-affinity cAMP-specific phosphodiesterase gene (HCP1) was mapped to human chromosome 8q13-q22. Since these genes are potential candidates for involvement in psychiatric or behavioral disorders, knowledge of their chromosomal localizations will facilitate the discovery of their association with disease genes as they are being mapped by linkage studies.  相似文献   
6.
7.
Authors injected a 1.5-2 cc Gax-Collagen into the tongue of 13 rats in order to examine the reactivity of the tissues around the graft and its attitude and duration. The research had practical purposes as the material is mainly used in E.N.T. for reconstructing the vocal cords. The animals have been sacrificed from 1 day to 9 months and the tongue subjected to the ordinary histologic methods. Our conclusions are as follows: a) a moderate inflammatory reaction following the introduction of the foreign body, then it attenuates and disappears at the third month; b) the implant is well tolerated, does not cause structural alterations in the surrounding tissues, in particular in the musculature where it is placed; c) a neovascularization appears, it lessens over the time, keeping itself only at the edge of the graft; d) in the formed fissures, fibroblasts, traces of collagen and neocollagen are present. All these conditions allow for taking root and the persistence of the implant. It is remarkable that the spherical form of the Gax-Collagen does not modify even if it has been implanted into a muscular organ and therefore subjected to severe and continuous mechanical stress.  相似文献   
8.
Summary The temporal development of infarcts was histochemically and functionally determined in porcine hearts. In one series of experiments (22 pigs), the distal third of the left anterior descending coronary artery (LAD) was transiently occluded for periods between 20 and 90 min and was reperfused for another 24h. At the end of the experiments, the infarcted myocardium of four tissue slices was determined with a tetrazolium stain and related to the risk region which was delineated by a fluorescent dye. Infarcts started to develop in the ischemic septum and the subendocardial layer of the free anterior wall between 20 and 35 min of ischemia. Thereafter, infarctions progressed rapidly from the inner towards the outer layer at risk. The jeopardized anterior left ventricular wall became almost completely infarcted within 60 min of ischemia. In a second series of experiments (10 pigs) recovery of systolic shortening was studied with implanted ultrasonic crystals over 3 weeks of reperfusion. At the end of the experiments, systolic shortening was about 75% of baseline level when ischemia had lasted between 20 and 35 min. Almost no recovery was observed when the occlusion time lasted 45 to 60 min. This study suggests that the assessment of myocardial infarction with a tetrazolium stain after 24 h of reperfusion corresponds very well with functional recovery after 3 weeks of reperfusion. Furthermore, determination of regional myocardial function of the ischemic, reperfused segment in the chronic stage may be considered an additional tool to evaluate therapeutic effects on infarct size in this model.The study was supported by a grant of Deutsche Forschungsgemeinschaft (DFG) Sonderforschungsbereich 330 Organprotektion Göttingen.This paper contains parts of the Habilitationsschrift of Dr. H. H. Klein.  相似文献   
9.
Endothelial selectins are crucial for the recruitment of leukocytes into sites of inflammation. On T cells, ligands for selectins become induced upon differentiation into the effector/memory stage. Initial in vitro studies suggested a correlation between the Th1 phenotype and ligand expression, but whether this also holds true in vivo remained uncertain. We here analyzed selectin ligands on CD4+ T cells producing IFN-gamma, IL-4 or IL-10, prototypic cytokines of the Th1, Th2 and Tr1 subset, respectively. We analyzed mice infected with influenza virus, the bacterium Listeria, and the parasites Toxoplasma (all Th1 models) or Nippostrongylus (Th2 model). A link between the Th1 phenotype and ligand expression was not found in vivo. Surprisingly, the potentially regulatory IL-10-producing T cells displayed the highest frequency of ligand-positive cells in general. Within the inflamed tissues, the frequencies of P-selectin-binding cells increased in the dominant subset, either Th1 or Th2. Up-regulation was also found for E-selectin ligands during influenza, but not Nippostrongylus infection. In conclusion, conditions driving T cell polarization into either Th1 or Th2 in vivo do not affect the expression of selectin ligands, but acquisition of P-selectin binding and hence migration into inflamed tissues is boosted by an inflammatory milieu.  相似文献   
10.
Electron microscopic study of human histoplasmosis   总被引:1,自引:0,他引:1  
  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