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   799篇
  免费   46篇
  国内免费   1篇
耳鼻咽喉   26篇
儿科学   3篇
妇产科学   8篇
基础医学   133篇
口腔科学   11篇
临床医学   85篇
内科学   122篇
皮肤病学   26篇
神经病学   82篇
特种医学   18篇
外科学   97篇
综合类   2篇
一般理论   1篇
预防医学   46篇
眼科学   8篇
药学   52篇
肿瘤学   126篇
  2021年   10篇
  2020年   7篇
  2019年   20篇
  2018年   13篇
  2017年   10篇
  2016年   14篇
  2015年   12篇
  2014年   16篇
  2013年   36篇
  2012年   40篇
  2011年   28篇
  2010年   25篇
  2009年   26篇
  2008年   43篇
  2007年   44篇
  2006年   37篇
  2005年   37篇
  2004年   38篇
  2003年   25篇
  2002年   42篇
  2001年   8篇
  2000年   12篇
  1999年   10篇
  1998年   9篇
  1997年   8篇
  1996年   13篇
  1995年   9篇
  1994年   8篇
  1993年   9篇
  1992年   10篇
  1991年   10篇
  1990年   17篇
  1989年   8篇
  1988年   14篇
  1987年   12篇
  1986年   12篇
  1985年   13篇
  1984年   8篇
  1983年   21篇
  1982年   12篇
  1981年   7篇
  1980年   8篇
  1979年   13篇
  1978年   10篇
  1977年   11篇
  1976年   6篇
  1975年   9篇
  1974年   9篇
  1973年   7篇
  1972年   5篇
排序方式: 共有846条查询结果,搜索用时 15 毫秒
41.
Selective inhibition of neuronal and inducible nitric oxide synthase (NOS) with 2-iminobiotin previously showed a reduction in brain cell injury. In the present study, we investigated the effects of 2-iminobiotin treatment on insulin-like growth factor-1 (IGF-1) expression, caspase activity and cytokine expression in a newborn piglet model of perinatal hypoxia-ischaemia. Newborn piglets were subjected to 1 h of hypoxia-ischaemia and were treated intravenously with vehicle or 2-iminobiotin. Vehicle-treated piglets showed reduced IGF-1 mRNA expression and increased caspase-3 activity and DNA fragmentation. 2-Iminobiotin treatment, administered immediately upon reperfusion, prevented these observations. No differences in caspase-8 and -9 activity and cytokine [interleukin (IL)-1alpha/beta, IL-6, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta] mRNA expression were demonstrated between vehicle- and 2-iminobiotin-treated piglets at 24 h following hypoxia-ischaemia. IGF-1 mRNA correlated inversely with caspase-3 and transferase-mediated dUTP-biotin in situ nick end labelling score in the cortex, but positively with caspase-8. Cytokine mRNA did not correlate with IGF-1 mRNA, caspase-3 activity or DNA fragmentation. The present results indicate that the previously demonstrated neuroprotective effect of 2-iminobiotin treatment after perinatal hypoxia-ischaemia coincided with a preservation of the endogenous IGF-1 production and reduced caspase-3 activity, but not with a significant decrease in cytokine production.  相似文献   
42.
Wernicke's encephalopathy presenting with severe dysphagia: a case report   总被引:1,自引:0,他引:1  
A 62-year-old man developed dysphagia 4 weeks before the classic symptoms and signs of Wernicke's encephalopathy appeared. Adequate treatment with parenteral thiamine resulted in complete recovery of all symptoms, including his dysphagia. This extraordinary presentation with dysphagia, and the unusual course of the disease, encouraged us to present this case history.  相似文献   
43.
Mitochondrial damage may play a key role in the development of necrotic and apoptotic hypoxic-ischemic (HI) brain damage. It has previously been shown that mitochondrial respiration is depressed in the cerebral cortex after HI in neonatal animals. The aim of the present study was to further characterize the time course of the mitochondrial impairment during reperfusion and the correlation between the respiratory control ratio and brain injury and activation of caspase-3. Rat pups were subjected to unilateral carotid artery ligation and exposed to hypoxia (7.7% oxygen). Mitochondrial respiration was measured 0-72 h after HI in a mitochondrial fraction isolated from cerebral cortex. Microtubule associated protein-2 (MAP2) and caspase-3 were analyzed with immunoblotting in cerebral cortex homogenates. In addition, the time course of caspase-3 activation was measured as DEVD cleavage. The mitochondrial respiratory control ratio in cerebral cortex decreased immediately after HI followed by a partial recovery at 3-8 h. Thereafter, a secondary drop occurred with a minimum reached at 24 h of reperfusion. The secondary loss of respiratory function was accompanied by depletion of MAP2, cleavage of caspase-3 and an increased caspase-3 -like activity at 3-24 h after the insult. In conclusion, the primary phase of mitochondrial dysfunction was paralleled by a moderate decrease of MAP2 and a limited activation of caspase-3. The secondary mitochondrial impairment was associated with neuronal injury and pronounced activation of caspase-3.  相似文献   
44.
The present study was designed to determine the effects of shock wave voltage (kV) on lesion size and renal function induced by shock wave lithotripsy (SWL) in the 6- to 8-wk-old pig. Each SWL-treated pig received 2000 shock waves at 12, 18, or 24 kV to the lower pole calyx of one kidney. A group of sham SWL pigs served as time controls. Bilateral GFR, renal plasma flow (RPF), and para-aminohippurate (PAH) extraction were measured 1 h before and 1 and 4 h after SWL in all treated and sham animals. The kidneys were removed at the end of each experiment for morphometric analysis. The SWL-induced lesion increased significantly in size as shock wave energy was increased from 12 to 24 kV. PAH extraction, a measure of tubular function, was not significantly affected at 12 kV, was transiently reduced at 18 kV, and was reduced for the duration of the experiment at 24 kV. GFR and RPF, however, were significantly and similarly reduced at the 1 h post-SWL period at all three kilovolt levels. At the 4-h post-SWL period, both GFR and RPF had returned to baseline levels. Lesion size and tubular injury were correlated with changes in kilovoltage, while changes in renal hemodynamics were already maximal at the lowest discharge voltage. These findings suggest that renal microvessels are highly sensitive to shock waves and that frank injury to tubules and vessels may be more closely related to discharge energy than is renal blood flow.  相似文献   
45.
The influence of glutathione (GSH) depletion on the radiation response and on the radiosensitizing efficiency of misonidazole (miso) has been studied in two types of mouse tumour and in mouse skin. Buthionine sulphoximine (BSO) has been administered in a variety of regimes, leading to a maximal depletion of GSH to 37% of control values in one tumour (CA MT) and 61% in the other (SA FA). Pretreatment with BSO did not alter the radiosensitivity of either tumour when treated with X-rays. It had a slight effect on the sensitizing efficiency of miso, corresponding to a factor less than three, which was detectable only at the highest X-ray doses used. No enhancement of miso efficiency was seen with 5 daily fractions. Prolonged administration of BSO resulted in a slight radiosensitization of mouse skin. When combined with miso the effect was very small and was only detectable at high X-ray doses. BSO however produced a marked enhancement of the acute toxicity of miso, as judged by lethality after large single doses.  相似文献   
46.
Human leukocyte interferon (IF) was tested for its capacity to modify the spontaneous cytotoxicity of human peripheral lymphocytes for allogeneic target cells in vitro. Pretreatment of lymphocytes with IF augmented their cytotoxicity whereas pretreatment of the target cells did not increase but possibly decreased their sensitivity to the spontaneous cytotoxicity of lymphocytes.  相似文献   
47.
48.
The major brain noradrenergic nucleus locus coeruleus (LC) has long been thought to be involved in states of alertness and cognitive processes. These functional characteristics make this nucleus interesting with regard to the signs of schizophrenia, especially the negative symptoms of the disease. In the present in-vivo electrophysiological study we analyse a putative interaction between endogenous kynurenic acid (KYNA) and the antipsychotic drugs clozapine and haloperidol on noradrenergic LC neurons. Previous studies have shown that systemically administered antipsychotic drugs increase the neuronal activity of LC noradrenaline (NA) neurons. In line with these findings, our results show that clozapine (1.25-10 mg/kg i.v.) and haloperidol (0.05-0.08 mg/kg i.v.) increased the firing rate of LC NA neurons in anaesthetized rats. Pretreatment with PNU 156561A (40 mg/kg i.v., 3 h), a potent inhibitor of kynurenine 3-hydroxylase, produced a 2-fold increase in rat brain KYNA levels. This treatment prevented the increase in firing rate of LC NA neurons induced by haloperidol (0.05-0.08 mg/kg i.v.) and clozapine in high doses (2.5-10 mg/kg i.v.). However, the excitatory action of the lowest dose of clozapine (1.25 mg/kg i.v.) was not abolished by elevated levels of brain KYNA. Furthermore, pretreatment with L-701,324 (4 mg/kg i.v.) a selective antagonist at the glycine site of the NMDA receptor prevented the excitatory effects of both clozapine and haloperidol. The present results suggest that the excitation of LC NA neurons by haloperidol and clozapine involves a glutamatergic component.  相似文献   
49.
A series of 203 consecutive patients with operable carcinoma of the breast was analysed with regard to correlations between a set of immunologic and clinical variables existing at the time of the diagnosis. No major correlations were revealed between immunologic variables on the one hand and clinical features or the course of the disease on the other. The well-known prognostic relevance of tumour size, involvement of the axilla and the histological grade of malignancy was evident.  相似文献   
50.
Radiation treatment of breast cancer patients (45.0 Gy) profoundly affected the peripheral blood lymphocytes. The number of these cells was markedly reduced with non-T-cells being more extensively depleted than T-cells immediately after radiation. The long-lasting lymphopenia, on the other hand, was mainly due to reduced number of T-cells. Antigen and mitogen stimulability, MLC reactivity, pokeweed (PWM)-induced immunoglobulin (Ig) production in vitro, and different cytotoxic functions decreased. Depletion of lymphocytes largely restored the radiation-depressed lymphocyte reactivity. The effects of in vitro exposure of blood lymphocytes to x-rays were similar to those seen after radiotherapy. Non-T-cells and T-cells with Fc-receptors for IgG were relatively radiosensitive. This latter observation agreed well with demonstrated increase of PWM-induced Ig synthesis after in vitro exposure to x-rays. T-suppressor cells defined by monoclonal antibodies were, however, radioresistant. The cytotoxic functions were reduced. No correlations were found between the pretreatment immunological status or the extent of radiation-induced immunological suppression, respectively, and prognosis.  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