全文获取类型
收费全文 | 3413733篇 |
免费 | 242655篇 |
国内免费 | 5708篇 |
专业分类
耳鼻咽喉 | 45774篇 |
儿科学 | 112367篇 |
妇产科学 | 92868篇 |
基础医学 | 489415篇 |
口腔科学 | 91543篇 |
临床医学 | 308418篇 |
内科学 | 655223篇 |
皮肤病学 | 73778篇 |
神经病学 | 274868篇 |
特种医学 | 129826篇 |
外国民族医学 | 906篇 |
外科学 | 513532篇 |
综合类 | 74678篇 |
现状与发展 | 15篇 |
一般理论 | 1232篇 |
预防医学 | 273919篇 |
眼科学 | 78764篇 |
药学 | 247923篇 |
11篇 | |
中国医学 | 7501篇 |
肿瘤学 | 189535篇 |
出版年
2021年 | 26104篇 |
2019年 | 26907篇 |
2018年 | 55348篇 |
2017年 | 42268篇 |
2016年 | 47652篇 |
2015年 | 36282篇 |
2014年 | 51040篇 |
2013年 | 76227篇 |
2012年 | 109400篇 |
2011年 | 127955篇 |
2010年 | 80675篇 |
2009年 | 71579篇 |
2008年 | 118852篇 |
2007年 | 127353篇 |
2006年 | 111102篇 |
2005年 | 109191篇 |
2004年 | 105973篇 |
2003年 | 102453篇 |
2002年 | 97530篇 |
2001年 | 150982篇 |
2000年 | 154853篇 |
1999年 | 129715篇 |
1998年 | 38161篇 |
1997年 | 33788篇 |
1996年 | 33704篇 |
1995年 | 31853篇 |
1994年 | 29414篇 |
1993年 | 27613篇 |
1992年 | 99778篇 |
1991年 | 96930篇 |
1990年 | 94296篇 |
1989年 | 90780篇 |
1988年 | 83597篇 |
1987年 | 81591篇 |
1986年 | 76496篇 |
1985年 | 73477篇 |
1984年 | 55173篇 |
1983年 | 46889篇 |
1982年 | 28266篇 |
1979年 | 50339篇 |
1978年 | 35727篇 |
1977年 | 29775篇 |
1976年 | 28415篇 |
1975年 | 30143篇 |
1974年 | 36393篇 |
1973年 | 34667篇 |
1972年 | 32693篇 |
1971年 | 30603篇 |
1970年 | 28491篇 |
1969年 | 26944篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
991.
Ethmoidal mucocoeles in children 总被引:1,自引:0,他引:1
Children presenting with ethmoidal mucocoeles are rare. Five children are presented with such findings, and the diagnosis, treatment and possible aetiology discussed. C.T. scanning was found to be the investigation of choice, while plain sinus X-rays correlated poorly with the presence of disease. Exenteration through an external approach was found to be satisfactory. In two cases drainage obstruction due to congenital abnormality was thought to be the underlying cause, while in four cases there was a strong history of atopy, indicating allergy as a possible reason for mucocoele formation. 相似文献
992.
993.
The incidence and mortality of acute epiglottitis were retrospectively analysed covering a 12-year period, 1975-1987. The diagnosis was made by the laryngoscopic findings in 95% of patients. Based on 902 hospitalized patients, a mean annual incidence of 4.9 cases per 100,000 children and adults was found. Although adult patients predominated (60%), the incidence was far higher in children, 13.8 per 100,000 compared with 3.9 per 100,000 in adults. Two peaks in incidence were identified, one for the youngest children, and the second for young adults (15-29 years). Over the years the incidence varied little in adults, but decreased significantly in children over the last 6 years studied. The data presented indicate acute epiglottitis to be a more frequent disorder than previously believed but with less risk of a fatal outcome. The mortality rate was below 1% in children and adults and the annual incidence of death from acute epiglottitis was estimated at 0.5 cases per million. The primary admission of these patients to ENT units seems to be the single factor having the most powerful impact on mortality. 相似文献
994.
B J Braakhuis D A Laarman J J Nauta M van Walsum G A van Dongen G B Snow 《Archives of otolaryngology--head & neck surgery》1989,115(9):1076-1078
Tumor material from 91 patients with squamous cell carcinoma of the head and neck was transplanted subcutaneously in athymic nude mice. In the first (man to mouse) passage, the calculated mean probability of tumor take in a single mouse was 11%. The probability of growth in the first passage was significantly better for moderately and poorly differentiated tumors than for well-differentiated tumors. Also, the implantation of lymph node material resulted in a significantly better tumor take rate than material taken from a primary tumor. Transplantability was not dependent on the following characteristics: localization, T or N stage of the tumor, or the sex of the patients. Once growth was established, all variables studied had no influence on the probability of growth in the subsequent mouse passages. A relationship between tumor growth in nude mice and patient prognosis could not be found. When transplanting head and neck squamous cell carcinoma in nude mice, it has to be recognized that some tumor characteristics will influence the success of tumor growth. 相似文献
995.
To determine whether well-appearing children found incidentally to be neutropenic are at risk for an infectious complication, 44 consecutive months of hematology laboratory records were reviewed. One hundred nineteen patients had medical record documentation regarding clinical course, serial white blood cell counts, and the absence of serious infections, chronic illnesses, or a family history known to be associated with neutropenia. The median duration of documented neutropenia was 13 days (range, 1 to 491 days). Infectious complications occurred in 4 of the 36 patients who had neutropenia for more than 30 days (2 with stomatitis, 1 with cellulitis, and 1 with pneumonia) but in none with shorter durations of neutropenia. There were no significant associations between the development of an infectious complication and either the initial absolute neutrophil count or the lowest documented absolute neutrophil count, nor was there a correlation between the initial absolute neutrophil count and the duration of neutropenia. These data indicate that infectious complications occur in otherwise well children with unexplained neutropenia that persists, but these infections are infrequent and usually are superficial. 相似文献
996.
997.
998.
This paper suggests that like ethanol, methanol also produces certain changes in the steady state level of monoamines in hypothalamus and striatum of albino rats. Though, the toxic manifestations of methanol are attributed to the metabolic end product of methanol viz. formic acid by several workers, we report here that the methanol-induced brain monoamine changes, at least, could be attributed to the direct action of methanol rather than to its metabolic end products like formaldehyde or formate. Studies in the steady state level of rat brain monoamines have shown that after methanol administration (3 g/kg), there is severe depletion of dopamine level in striatum but a significant increase in the level of dopamine, serotonin and 5-hydroxy indole acetic acid in hypothalamus. At the same time, norepinephrine and epinephrine levels are reduced in hypothalamus as well as in striatum. These effects do not seem to be induced by metabolic acidosis. The changes in monoamine levels are very well correlated with the blood and brain level of methanol as evidenced by maintaining a higher methanol level either by simultaneous administration of ethanol or by blocking methanol metabolism by pretreatment with 4-methyl pyrazole and 3-amino-1,2,4-triazole. It is thus postulated that monoamine changes induced by methanol appear to be the direct effect of methanol per se on the monoaminergic neuronal membranes. 相似文献
999.
Release of cortical catecholamines by visual stimulation requires activity in thalamocortical afferents of monkey and cat 总被引:3,自引:0,他引:3
R T Marrocco R F Lane J W McClurkin C D Blaha M F Alkire 《The Journal of neuroscience》1987,7(9):2756-2767
Catecholamine (CA) release was measured in vivo in the monkey and cat visual cortices electrochemically. Stereate-modified, graphite-paste electrodes were used to monitor changes in norepinephrine and dopamine release. Micromolar changes in CA concentration were obtained by stimulation of the eye with nonspecific (strobe) or specific (oriented bars, radial gratings) stimuli. CA release depended on which eye was illuminated. Electrodes passed tangentially through the striate area recorded release following visual stimulation of one eye or the other in succession, and the shift in eye dominance occurred at about 500 microns intervals. The magnitude of CA release was highly correlated with the ocular dominance of neuronal activity measured with tungsten microelectrodes. Light-stimulated release was not recorded in monkey area V2, V4, or somatosensory area 1, but was recorded in cat V2, suggesting that the presence of LGN afferents is associated with CA release. Results are discussed in terms of the role of geniculate activity and the specific role of CAs in cortical information processing. 相似文献
1000.
Hernia through the foramen of Winslow: a complication of cholecystectomy. A case report 总被引:2,自引:0,他引:2
In 151 years since first described, there have been 112 reported cases of hernia through the foramen of Winslow (HFW). All thus far have described HFW as a primary entity. The case reported appears to be unique with HFW as a surgical complication. HFW is the least common of internal hernias. The primary symptom is pain referred from the herniated organ and the hepatoduodenal ligament. An interesting sign is that the patient is found curled up or stooped over for pain relief. Anatomic factors implicated in HFW are an enlarged epiploic foramen, a floppy cecum and ascending colon, or abnormal length of small bowel mesentery. Tension on these structures causes pain with the torso extended. Distention of bowel in the lesser sac mimics gastric obstruction. Organs herniated are: small bowel (63%); cecum, ascending colon, and terminal ileum (30%); and transverse colon (7%). Of 25 cases reported since 1966, cecal herniation comprised two-thirds. The diagnosis may be made radiologically and the treatment is surgical. The case and a review of the literature are presented with attention to the anatomy. Also provided are the signs and symptoms of this interesting and perplexing diagnosis. 相似文献