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   2123篇
  免费   103篇
  国内免费   16篇
耳鼻咽喉   32篇
儿科学   30篇
妇产科学   6篇
基础医学   211篇
口腔科学   36篇
临床医学   124篇
内科学   533篇
皮肤病学   14篇
神经病学   170篇
特种医学   96篇
外科学   382篇
综合类   8篇
预防医学   35篇
眼科学   75篇
药学   230篇
中国医学   6篇
肿瘤学   254篇
  2023年   30篇
  2022年   27篇
  2021年   61篇
  2020年   42篇
  2019年   44篇
  2018年   40篇
  2017年   48篇
  2016年   54篇
  2015年   80篇
  2014年   83篇
  2013年   101篇
  2012年   157篇
  2011年   163篇
  2010年   76篇
  2009年   73篇
  2008年   111篇
  2007年   109篇
  2006年   137篇
  2005年   119篇
  2004年   121篇
  2003年   121篇
  2002年   117篇
  2001年   36篇
  2000年   42篇
  1999年   37篇
  1998年   20篇
  1997年   15篇
  1996年   8篇
  1995年   10篇
  1994年   11篇
  1993年   10篇
  1992年   14篇
  1991年   14篇
  1990年   8篇
  1989年   11篇
  1988年   13篇
  1987年   18篇
  1986年   14篇
  1985年   5篇
  1984年   8篇
  1983年   5篇
  1982年   5篇
  1979年   3篇
  1978年   3篇
  1977年   2篇
  1976年   2篇
  1971年   5篇
  1966年   1篇
  1962年   1篇
  1958年   1篇
排序方式: 共有2242条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Cytomegalovirus (CMV) diseases commonly occur in allograft recipients in the early post-transplant period. However, factors responsible for the high incidence of CMV diseases during this period are not yet fully defined. METHODS: Wistar-Furth (WF; RT-1(u)) rats were inoculated with 10(4) plaque-forming units (PFU) of rat CMV (RCMV) intraperitoneally, and then transplanted with allogeneic lungs from Dark Agouti (DA; RT-1avl) rats or stimulated with 10(7) mitomycin C-treated spleen cells from DA rats by daily sub-cutaneous injections for 2 weeks. No immunosuppressive agent was used. Naive WF rats and WF rats grafted with syngeneic lungs or cells were used as controls. The level of RCMV replication in rats was assessed by infectious virus titers in tissues. RESULTS: The virus titers in salivary glands of allogeneic and syngeneic lung graft recipients were significantly higher than in naive WF rats. The level of RCMV replication in rats stimulated with allogeneic spleen cells was significantly higher than in the syngeneic recipient rats: virus titers in the salivary gland of allogeneic and syngeneic recipients reached 4.61 +/- 0.33 and 4.00 +/- 0.37 log(10) PFU/g tissue, respectively, at 14 days post-infection (p = 0.015). The augmented viral replication in allogeneic recipients was confirmed by an increase in the number of RCMV antigen-positive macrophages present in tissue sections of the salivary gland. CONCLUSIONS: Acute lung allograft rejection and allogeneic spleen cell stimulation enhance CMV replication in the salivary gland of rats. Various responses to allogeneic antigens occurring in the process of acute allograft rejection could be risk factors for post-transplant CMV replication and infection.  相似文献   
2.
A 53-year-old man with adult T-cell leukemia (ATL) developed progressive left hemiparesis and left homonymous hemianopsia. Magnetic resonance imaging (MRI) one month later showed multiple high-intensity lesions in the white matter of both occipital lobes, with predominance in the right side. Detection of JCV genome with polymerase chain reaction in his cerebrospinal fluid subsequently confirmed the diagnosis of progressive multifocal leukoencephalopathy (PML). He was admitted to our hospital. The serum level of soluble interleukin-2 receptor in the patient increased, and both edema and new Gd-enhanced lesions were observed in the cortex of the occipital lobe. He was treated with systemic administrations of Pirarubicin. Cyclophosphamide, and Prednisolone. as well as intrathecal injection of Methotrexate and Cytarabine. Although these treatments temporarily alleviated the symptoms of PML. the ATL spread to the liver and kidney. He died of multiple organ failure. Analysis of his JCV genes revealed that there were three types of rearrangements in the regulatory domains of the JCV genes. All three types lacked the domain B. and two had duplicate domain A. This is the first report of the simultaneous detection of three different types of rearrangements in JCV genes in a single patient. It has been reported that white-matter lesions caused by typical PML are not enhanced in Gd-MRI. However. the lesions seen in this patient were enhanced in Gd-MRI. Such enhancement might be attributable to the modification of the lesions through the direct invasion of ATL cells to the central nervous system.  相似文献   
3.
The diuretic and the antihypertensive actions of torasemide were examined in renal and genetic hypertensive rats and compared to the effects of furosemide. Oral administration of torasemide (1 and 3 mg/kg) elicited a dose-dependent increase in the excretion of urine and electrolytes and elevated the urinary Na/K ratio in both renal and genetic hypertensive rats. Torasemide and furosemide had a similar maximum diuretic effect in the normotensive Wistar rat and the spontaneously hypertensive rat (SHR). However, the diuretic activity of furosemide was weaker in the renal hypertensive rat (RHR). Torasemide showed approximately 30 times greater diuretic potency than furosemide. Torasemide and furosemide demonstrated hypotensive action in hypertensive rat models, but not in the normotensive Wistar rat. Especially in the RHR, torasemide exhibited a more potent hypotensive action than furosemide. These results show that the diuretic and antihypertensive activities of torasemide are effective in various rat models of hypertension, while the diuretic activity of furosemide is weak in certain hypertensive rat models. © 1992 Wiley-Liss, Inc.  相似文献   
4.
Objective. Employing [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to assess the correlation between the effect of deep brain stimulation (DBS) on the subthalamic nucleus (STN) and the regional cerebral metabolic rate of glucose (rCMRGlc) in advanced Parkinson's disease patients (N = 8). Materials and Methods. On the basis of patients’ diary records, we performed FDG‐PET during the off‐period of motor activity with on‐ or off‐stimulation by STN‐DBS on separate days and analyzed the correlation between changes in motor symptoms and alterations in the rCMRGlc. Result. When FDG‐PET was performed, the motor score on the unified Parkinson's disease rating scale (UPDRS) was 64% lower with on‐stimulation than with off‐stimulation (p < 0.001, Wilcoxon single‐rank test). STN‐DBS increased the rCMRGlc in the posterior part of the right middle frontal gyrus, which corresponded to the premotor area, and the right anterior lobe of the cerebellum (p < 0.005, paired t‐test). No region exhibited a decrease in rCMRGlc. Among the items of the UPDRS motor score, the changes in resting tremor and rigidity of the left extremities showed a significant correlation with the changes in rCMRGlc observed in the right premotor area (p < 0.02 and p < 0.05, respectively, Spearman's rank correlation). Conclusions. STN‐DBS either activates the premotor area or normalizes the deactivation of the premotor area. These FDG‐PET findings obtained are consistent with the idea that STN‐DBS modifies the activities of neural circuits involved in motor control.  相似文献   
5.
Two patients with oculomotor palsy caused by midbrain infarction are reported. In the first, pupillary reaction was affected and in the second this reaction was spared. Because the lesions in the anterior part of the tegmentum were in the upper midbrain in the first patient and in the lower midbrain in the second, it is suggested that the pupillary components of the oculomotor nerve are located in the upper midbrain.  相似文献   
6.
7.
A 34-year-old male presented with central diabetes insipidus accompanied by upbeat nystagmus and cerebellar ataxia. The patient without family history of above began to walk at the age of 2 years. Polyposia and polyuria were noted at the age of about 4 years. Dysbasia developed at the age of about 7 years. From the age of 30, lalopathy appeared together with various clinical symptoms including cataracts, disturbed intelligence, upbeat nystagmus, abnormal ocular movements, ataxic speech, cerebellar ataxia and reduction of the muscle tone of the limbs, and hypotonic polyuria. Abnormal laboratory findings included square wave jerks, upbeat nystagmus, and "bow tie" nystagmus by EOG, atrophy of the cerebellum and the brainstem by CT, a slight prolongation of the P300 latency, and a central diabetes insipidus pattern by water deprivation test and Carter-Robbins tests. There have been occasional reports of diabetes insipidus complicated by cerebellar ataxia, but in no earlier reports has diabetes insipidus been concurrent with abnormal ocular movements such as upbeat nystagmus. A degenerative disease primarily of the posterior lobe of the hypophysis, hypothalamus, cerebellum, and brainstem was suspected.  相似文献   
8.
Recombinant human interleukin-11 (rHuIL-11) and recombinant human bone morphogenetic protein-2 (rHuBMP-2) have been shown to act synergistically in the induction of osteoblast differentiation. To determine whether these two proteins can be used clinically in fracture healing and reconstructive surgery, we investigated whether rHuIL-11 and rHuBMP-2 act synergistically to heal segmental bone defects in a rabbit model. A 1.5-cm segmental defect was created in the right ulnar diaphysis of 20 Japanese white rabbits. Polylactic-co-glycolic acid (PLGA)-coated gelatin sponges (PGS) permeated with rHuBMP-2 (n = 8), rHuIL-11 plus rHuBMP-2 (n = 8), or rHuIL-11 (n = 4) were implanted into the bone defects. Radiographs were scored by two independent observers for bone formation and union rates after 2, 3, 4, and 8 weeks. Bone formation was higher in rabbits implanted with rHuBMP-2 plus rHuIL-11 than in those implanted with rHuBMP-2 alone, reaching statistical significance after 4 weeks. At early time points, the union rate in rabbits implanted with rHuBMP-2 plus rHuIL-11 was higher than in rabbits implanted with rHuBMP-2. At 2, 4, and 8 weeks, new bone volume was significantly higher in rabbits administered rHuIL-11 plus rHuBMP-2 than in those given rHuBMP-2 alone. In contrast, mechanical testing after 8 weeks showed that bone strength in the two groups of rabbits was equivalent. These findings show that rHuIL-11 and rHuBMP-2 act synergistically to accelerate bone formation without affecting bone strength. Treatment with a combination of rHuIL-11 and rHuBMP-2 may thus be of great benefit in fracture healing and for patients undergoing reconstructive surgery.  相似文献   
9.
Corneal epithelial lesions distinguish vernal keratoconjunctivitis (VKC) from other ocular allergic diseases. Such lesions result from degradation of the corneal epithelial basement membrane, which comprises mostly type IV collagen and laminin. Matrix metalloproteinase 2 (MMP-2) and MMP-9 catalyze the degradation of these 2 extracellular matrix proteins. The possible role of MMP-2 and MMP-9 in the pathogenesis of corneal lesions associated with VKC was investigated by assaying tear fluid for the presence of these enzymes. Tear fluid was collected from 6 eyes of 6 patients with active VKC, 14 eyes of 14 patients with active allergic conjunctivitis, and 6 eyes of 6 nonallergic healthy volunteers. Gelatin zymography revealed that the tear fluid of healthy volunteers contained inactive proforms of both MMP-2 and MMP-9 but not the active forms of these enzymes. Active forms of MMP-2 or MMP-9 were detected in a minority of patients with allergic conjunctivitis. However, with the exception of one individual for whom active MMP-9 was not detected, tear fluid from all patients with VKC contained both proforms and active forms of MMP-2 and MMP-9. These results implicate MMP-2 and MMP-9 in the pathogenesis of corneal epithelial disorders associated with VKC.  相似文献   
10.
It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.  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