全文获取类型
收费全文 | 1352849篇 |
免费 | 75667篇 |
国内免费 | 8084篇 |
专业分类
耳鼻咽喉 | 15883篇 |
儿科学 | 37392篇 |
妇产科学 | 29458篇 |
基础医学 | 178298篇 |
口腔科学 | 35902篇 |
临床医学 | 120364篇 |
内科学 | 242885篇 |
皮肤病学 | 28129篇 |
神经病学 | 91118篇 |
特种医学 | 52113篇 |
外国民族医学 | 173篇 |
外科学 | 180797篇 |
综合类 | 94232篇 |
现状与发展 | 2篇 |
一般理论 | 250篇 |
预防医学 | 121248篇 |
眼科学 | 28558篇 |
药学 | 95678篇 |
5篇 | |
中国医学 | 10243篇 |
肿瘤学 | 73872篇 |
出版年
2021年 | 11150篇 |
2019年 | 12022篇 |
2018年 | 19802篇 |
2017年 | 13976篇 |
2016年 | 14676篇 |
2015年 | 16561篇 |
2014年 | 19634篇 |
2013年 | 29917篇 |
2012年 | 45020篇 |
2011年 | 62082篇 |
2010年 | 32931篇 |
2009年 | 25593篇 |
2008年 | 54427篇 |
2007年 | 70012篇 |
2006年 | 68771篇 |
2005年 | 60882篇 |
2004年 | 60661篇 |
2003年 | 58292篇 |
2002年 | 54128篇 |
2001年 | 65260篇 |
2000年 | 61588篇 |
1999年 | 54195篇 |
1998年 | 17459篇 |
1997年 | 17009篇 |
1996年 | 17125篇 |
1995年 | 15983篇 |
1994年 | 14306篇 |
1993年 | 10100篇 |
1992年 | 31541篇 |
1991年 | 30357篇 |
1990年 | 29117篇 |
1989年 | 27757篇 |
1988年 | 25692篇 |
1987年 | 24012篇 |
1986年 | 22732篇 |
1985年 | 21005篇 |
1984年 | 15192篇 |
1983年 | 12815篇 |
1979年 | 13992篇 |
1978年 | 9752篇 |
1977年 | 8372篇 |
1976年 | 7970篇 |
1975年 | 8961篇 |
1974年 | 10713篇 |
1973年 | 10377篇 |
1972年 | 9698篇 |
1971年 | 9120篇 |
1970年 | 8824篇 |
1969年 | 8354篇 |
1968年 | 7764篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
N Gilmore L Cherian W R Klemm 《Progress in neuro-psychopharmacology & biological psychiatry》1991,15(1):91-104
1. This laboratory has previously reported that pretreatment with ganglioside, or even with its constituent, sialic acid (SA), can attenuate certain intoxicating effects of ethanol. It was important to see if these findings could be replicated, particularly by using other measures of ethanol effects. Herein we report that pretreatment with either gangliosides or SA attenuated ethanol-induced decrements in locomotion, nose-poke exploration, and anxiety, but not body temperature. 2. An ethanol dose of 4 gm/kg caused a temperature drop of about 3 degrees C, which was unaffected by any pretreatment. The onset to sleep, however, was delayed an average of 18 or 36 secs in mice pretreated with ganglioside or SA, respectively. Ethanol-only (4 gm/kg) depressed mean cumulative locomotor activity to 31% of normal, whereas the depression was 83% of normal with beef brain ganglioside pretreatment. At 2 gm/kg ethanol alone decreased nose poking in a hole-board test to 29% of normal, but the depression was only 55-63% of normal with SA or ganglioside pretreatment. In a staircase climbing anxiety test, this dose of ethanol had no effect by itself, but both ganglioside and SA pre-treatment increased climbing by 22%. Ethanol did depress rearing to only 11% of normal, whereas rearing was 51 and 99% of normal with SA and ganglioside pretreatment, respectively. In a dark-preference test, ethanol-only caused mice to spend 64% of the time in the light, compared to 31% for controls. Time in the light was only 39 and 46% with ganglioside and SA pretreatment, respectively. 3. Blood levels of ethanol were not significantly affected by pretreatment. 4. When given alone, gangliosides significantly stimulated locomotion and staircase climbing. SA significantly decreased rearing in the staircase test. Both gangliosides and SA tended to increase nose poking, number of crossings in the dark-preference test, and time in a lighted compartment. Thus, it is possible that some of the attenuation of intoxication is attributable to non-specific stimulant properties of gangliosides and SA. 相似文献
992.
R. N. KALARIA ‡‡ P. G. GALLOWAY† G. PERRY‡ ‡‡ 《Neuropathology and applied neurobiology》1991,17(3):189-201
Amyloid P (AP) component is present in all types of systemic amyloid deposits. Recently, it has been shown to be also present in cerebral amyloid lesions of Alzheimer's disease (AD). In this study, we used immunocytochemical methods to extend these findings at the electron microscope level and characterize the spectrum of AP immunoreactivity in neurofibrillary pathology (NFP) of AD and other neurodegenerative disorders including Down's syndrome (DS), Creutzfeldt-Jakob, Parkinson's, Pick's and diffuse Lewy body diseases and progressive supranuclear palsy. In AD and DS, AP immunoreaction product was evident in all the classical amyloid lesions and NFP in a large sample of all cortical areas examined. The distribution and relative intensity of immunostaining was similar to that of thioflavin S staining in serial sections. In many cases, however, plaques and vessels stained by anti-AP serum were not apparent with thioflavin S. Serial sections immunostained with antiserum to amyloid A, C-reactive protein or to other proteins involved in systemic amyloidoses and the acute phase response showed no evidence of staining in any of the cerebral lesions. Electron microscopy confirmed that AP immunoreactivity was associated with the abnormal filaments characteristic of NFP as well as amyloid fibrils found in plaques and vessels showing congophilic amyloid angiopathy. Plaques of Creutzfeldt-Jakob disease, Pick bodies of Pick's disease, tangles and Lewy bodies in Parkinson's disease and a subpopulation of Lewy bodies in the diffuse Lewy body disease coexistent with AD were also stained. With the exception of vessels in two of the five cases, AP was not detected in age-matched controls. Our observations indicate AP to be a consistent feature of cerebral NFP and amyloid deposits. 相似文献
993.
Gamma-aminobutyric acid (GABA) in the thalamus has mainly been associated with the inhibitory modulation of the sensory and cortical flow of information via a 'classical', chloride-dependent, GABAA receptor-mediated action. However, the discovery of a late, long-lasting potassium-dependent inhibitory postsynaptic potential (IPSP) mediated by GABAB receptors present on thalamocortical cells, has allowed new insights into our understanding of the physiological role of this neurotransmitter. In particular, work on the dorsal lateral geniculate nucleus indicates that together with a relatively weak inhibition, GABAB receptor-mediated IPSPs 'prepare' thalamocortical cells for burst firing by activating low-threshold calcium potentials. Thus, GABA in the thalamus can no longer be viewed only as a 'classical' inhibitory transmitter but also as a neuromodulator with a 'priming' role for burst firing excitation. This dual role of GABAB receptors in inhibition and excitation of thalamocortical cells might allow different interpretations of earlier findings in animals and humans, both in healthy and pathological conditions. It will also help to identify new functions for postsynaptic GABAB receptors in other parts of the central nervous system. 相似文献
994.
N M Whear J D Langdon D W Macpherson 《International journal of oral and maxillofacial surgery》1991,20(6):357-359
A new surgical technique for the treatment of recurrent temporomandibular joint subluxation or dislocation is described. Following a horizontal osteotomy and down-fracture of the articular eminence an inter-positional bovine cartilage xenograft is inserted in order to augment the vertical height of the eminence. The procedure combines simplicity with minimal post-operative morbidity. The increase in eminence height is both predictable and stable. 相似文献
995.
996.
997.
The authors investigated the effect on the brain of red blood cells that had been modified by contrast media. Rat blood was mixed with an equivolume of contrast media, and up to 200 microL of the mixture was infused to the internal carotid artery of the rat. Evans blue was administered intravenously to assess the integrity of the blood-brain barrier (BBB). Immediately after the death of the animal, or 2.5 hours after the infusion, the brain was removed for evaluation of the degree of BBB destruction and edema. Extensive destruction of the BBB, cerebral edema, and death of the animals were induced by infusion of blood mixed with an ionic contrast medium, such as diatrizoate and iothalamate, which deformed red blood cells. Microscopic observation showed atrophy and necrosis of nerve cells and decomposition of nerve fibers in the affected area of the brain. Cerebral damage was not observed in rats injected with blood mixed with a nonionic contrast medium such as iopamidol, iopromide, or metrizamide, which had less effect on red blood cells. Cerebral damage also was observed in the rats injected with blood mixed with a hyperosmotic solution of mannitol, as well as washed red blood cells mixed with an ionic contrast medium. This study's results indicate that hyperosmotic ionic contrast media affect red blood cells and cause disturbance in cerebral circulation. 相似文献
998.
C A González G López-Abente M Errezola A Escolar E Riboli I Izarzugaza M Nebot 《International journal of epidemiology》1989,18(3):569-577
A case-control study on bladder cancer was carried out in four regions of Spain. The study included 497 cases (438 males and 59 females), 583 hospital controls and 530 population controls matched by sex, age and residence. The present paper reports the results of the analyses on occupational history. Among men, an increased risk of bladder cancer was found for textile workers (OR = 1.97, 95% CL 1.2-3.3), mechanics and maintenance workers (OR = 1.86, 95% CL 1.2-2.8), workers in the printing industry (OR = 2.06, 95% CL 1.0-4.3) and for managers (OR = 2.03, 95% CL 1.2-3.5). The risk was highest among those first employed in the textile industry before the age of 25 and prior to 1960. Among mechanics the risk was highest for those who started after the age of 25 and later than 1960. The OR for smokers who had also been employed in one of the high risk occupations was 7.82 (95% CL 4.4-14.0) which is compatible with a multiplicative effect of joint exposure to tobacco and occupational hazards. 相似文献
999.
N D Hawass M G el-Badawi J A Fatani A A Meshari F S Abbas Y B Edrees F A Jabbar M Banna 《AJNR. American journal of neuroradiology》1987,8(4):691-695
To assess the length of the spinal cord relative to the vertebral column during fetal development, we performed translumbar myelograms on 340 spontaneously aborted fetuses. Of these, 146 were selected for study. There were 76 males and 70 females, with fetal age ranging from 7 to 33 weeks. Significant variation in the level of spinal cord termination was found in fetuses between 12 and 25 weeks gestational age. In fetuses between 25 and 33 weeks gestational age, the cord ended at or above the third lumbar vertebra. 相似文献
1000.
G F Sasso M Ceccanti E Nardi G Valicenti M A Savina N Stella F Zacco 《Panminerva medica》1989,31(1):30-33
The activity of LCAT (the controlling enzyme for cholesterol esterification in plasma) is known to be reduced in alcoholic cirrhosis, while little is known about early stage (liver steatosis) alcoholics. In this study, LCAT activity was assayed by Stokke and Norum's method, before and after a 15-day sobriety period, in liver steatosis and in cirrhosis alcoholics. Before alcohol withdrawal, LCAT activity was depressed in both groups. After the sobriety period, LCAT activity was significantly raised in liver steatosis patients, but was still lower than in controls; in cirrhosis patients, it was increased, but not significantly. According to our results, LCAT activity impairment in alcoholic liver disease is sustained by both the hypothesized mechanisms, alcohol-related metabolic disorders and lowered LCAT-enzyme production, but to different degrees, depending on the stage of the disease. In liver steatosis, metabolic disorders play a major role, as a liver-impairment-induced decrease in LCAT production seems rather unlikely, and increased LCAT activity is more likely to be sustained by metabolic normalisation than by any recovery of the damaged liver. However, the lack of improvement in about 20% of patients, and the fairly wide scattering of individual data, suggest a minor LCAT production impairment in liver steatosis too. In cirrhosis, the major role seems to be played by a permanent decrease in LCAT production, as no significant rise in LCAT activity was observed after alcohol withdrawal. However the restored LCAT activity observed in some patients could be related to improvement in the metabolic disorder, thus confirming the effectiveness of this mechnism in cirrhosis too.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献