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   3413733篇
  免费   242655篇
  国内免费   5708篇
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
  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.
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.
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.
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   
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