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   6441篇
  免费   307篇
  国内免费   14篇
耳鼻咽喉   89篇
儿科学   89篇
妇产科学   61篇
基础医学   819篇
口腔科学   114篇
临床医学   364篇
内科学   1455篇
皮肤病学   74篇
神经病学   460篇
特种医学   192篇
外科学   1340篇
综合类   16篇
预防医学   163篇
眼科学   214篇
药学   496篇
中国医学   11篇
肿瘤学   805篇
  2023年   28篇
  2022年   84篇
  2021年   136篇
  2020年   72篇
  2019年   87篇
  2018年   104篇
  2017年   79篇
  2016年   105篇
  2015年   87篇
  2014年   116篇
  2013年   180篇
  2012年   291篇
  2011年   303篇
  2010年   189篇
  2009年   160篇
  2008年   269篇
  2007年   284篇
  2006年   252篇
  2005年   274篇
  2004年   284篇
  2003年   325篇
  2002年   281篇
  2001年   197篇
  2000年   221篇
  1999年   199篇
  1998年   64篇
  1997年   49篇
  1996年   63篇
  1995年   50篇
  1994年   56篇
  1993年   47篇
  1992年   150篇
  1991年   141篇
  1990年   146篇
  1989年   169篇
  1988年   153篇
  1987年   152篇
  1986年   136篇
  1985年   129篇
  1984年   91篇
  1983年   53篇
  1979年   67篇
  1978年   34篇
  1977年   37篇
  1975年   30篇
  1974年   32篇
  1972年   27篇
  1969年   35篇
  1968年   29篇
  1967年   26篇
排序方式: 共有6762条查询结果,搜索用时 109 毫秒
1.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
2.
3.
Objective: Paraplegia remains a serious complication of aortic operations. The production of free radicals during reperfusion after transient ischemia is believed to induce secondary spinal neuronal injury, resulting in paraplegia. The aim of the present study was to clarify the protective effect and method of administration of antioxidants on the neurological and histological outcome in the animal model for reperfusion injury after transient spinal cord ischemia. Methods: New Zealand white rabbits underwent surgical exposure of the abdominal aorta that was clamped for 15 minutes to achieve spinal cord ischemia. Group A animals received two 10 mg/kg doses of 3-methyl-l-phenyl-2-pyrazolin-5-one (MCI-186) at the time of release of the aortic clamp and 30 minutes later. In group B, MCI-186, 5 mg/kg, was given three times, at the time of aorta clamp release, 30 minutes and 12 hours later. In group C (control group), one dose of vehicle was administered. Neurological status was assessed using modified Tarlov’s score until 168 hours after operation. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage. Results: Groups A and B animals had better neurological function than group C (p(0.001). In contrast, group C animals exhibited paraplegia or paraparesis with marked neuronal necrosis. The number of surviving neurons within examined sections of the spinal cord was significantly greater in group B than in group C (p(0.001). Conclusion: In a 15-minute ischemia-reperfusion model using rabbits, systemic repetitious administration of MCI-186, a free radical scavenger, was found to have a protective effect on the spinal cord neurons both neurologically and histologically. We postulate that the drug minimizes the delayed neuronal cell death for reperfusion injury after transient ischemia by reducing the free radical molecules. Moreover, it was thought that we could protect delayed neuronal cell death more effectively by administering MCI-18612 hours later.  相似文献   
4.
5.
Binding profile of SM-9018, a novel antipsychotic candidate   总被引:3,自引:0,他引:3  
The present study employed various receptor-binding assays to clarify the biochemical characteristics of SM-9018. SM-9018 possessed very high affinity for 5-HT2, D2 and 5-HT1A receptors (Ki = 0.61, 1.4 and 2.9 nM, respectively), and it had moderate affinity for alpha 1 and D1 receptors (Ki = 17 and 41 nM, respectively). However, SM-9018 had only negligible affinity for alpha 2, opiate, glutamate, phencyclidine, benzodiazepine and GABAA receptors. These results suggest that SM-9018 may be a novel antipsychotic agent with binding affinity for 5-HT2 and 5-HT1A receptors.  相似文献   
6.
Gliomatosis cerebri with good prognosis   总被引:4,自引:0,他引:4  
A 52-year-old man was admitted to our clinic with severe headache and bilateral papilledema. Magnetic resonance (MR) images on admission demonstrated diffuse swelling of the cerebral cortex without formation of a tumor mass. Biopsy revealed diffuse infiltration with neoplastic glial cells. After radiation and chemotherapy, the MR images returned to normal. The morphological and neurological features of the present case met the criteria for gliomatosis cerebri. However, this patient showed an unusually good response to radiation and chemotherapy.  相似文献   
7.
Modifying potentials of various chemicals on tumor development were investigated in a wide-spectrum organ carcinogenesis model using male F344/DuCrj rats. The animals were treated with N-nitroso-diethylamine (100 mg/kg body weight, ip, single injection at the commencement of the study), N-methyl-N-nitrosourea (20 mg/kg body weight, ip, 4 times during weeks 1 and 2) and N-bis(2-hydroxypropyl)nitrosamine (0.1% in drinking water, during weeks 3 and 4) for multi-organ initiation and then were given one of 14 test chemicals including 6 hepatocarcinogens, 7 non-hepatocarcinogens and 1 non-carcinogen, or basal diet for 16 weeks. All rats were killed at the end of week 20, and the major organs were carefully examined for preneoplastic and neoplastic lesions. Immunohistochemical demonstration of glutathione S -transferase-positivc foci was also used for quantitative assessment of liver preneoplastic lesion development. Modifying effects were shown for 11 out of 14 test agents in the liver, forestomach, glandular stomach, lung, urinary bladder or thyroid, 7 of them targeting more than two organs. This was the first demonstration to our knowledge that cloflbrate possesses enhancing potential for urinary bladder carcinogenesis and an inhibiting effect on thyroid carcinogenesis. Caprolactam showed no effect in any organ, in agreement with its established inactivity. The results indicated that the system could be reliably applied as a medium-term multiple organ bioassay for assessment of the modification potential of test agents in unknown target sites.  相似文献   
8.
9.
A 49-year-old Japanese man presented with chronic granulomatous uveitis in his left eye. Later he developed macular subretinal neovascularisation. The chest x-ray showed bilateral hilar lymphadenopathy. Bronchoscopy and gallium-67 scanning were positive, PPD skin test negative, and serum angiotensin converting enzyme (ACE) levels increased. Ophthalmoscopy and fluorescein angiography of the left eye showed perivasculitis, retinochoroidal exudates, snow banking, and vitreous opacity. On these findings, the diagnosis of sarcoidosis was made. Treatment was based on topical corticosteroids, mydriatics, beta blockers, and oral carbonic anhydrase inhibitors. After 15 months the visual acuity decreased in the left eye, and a neovascular membrane was observed in the macula. Fluorescein angiography confirmed subretinal neovascularisation. Almost two years later the patient still has the neovascular membrane in his left eye.  相似文献   
10.
Electroencephalographic (EEG) studies were performed to examine the effects of SM-3997 on the spontaneous EEG, EEG arousal responses, recruiting responses and hippocampal afterdischarges in rabbits and the spontaneous EEG in chronically electrode-implanted rats. In acute experiments using rabbits, SM-3997 at doses of 1-3 mg/kg, i.v., produced low-voltage fast waves in cortical EEG and slow waves with reduction of the amplitude in hippocampal EEG. The drug at doses of 1-3 mg/kg, i.v., dose-dependently inhibited the threshold stimulus voltages in EEG arousal responses induced by stimulation of the midbrain reticular formation and slightly inhibited the threshold in recruiting responses by stimulation of the centromedian nucleus of the thalamus. However, the cortical and hippocampal afterdischarges induced by hippocampal stimulation remained unaffected by SM-3997 at doses up to 3 mg/kg, i.v., while they were inhibited by diazepam of 1 mg/kg, i.v. In the study using rats in which electrodes were chronically implanted, SM-3997 at doses of 10-30 mg/kg, i.p., also produced low voltage fast waves in cortical EEG and slow waves of reduced amplitude in hippocampal EEG; and it simultaneously caused flat body posture. These results suggest that SM-3997 acts on both the cerebral cortex and hippocampus, inducing much more pronounced inhibition on the midbrain reticular formation-hippocampal system  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