全文获取类型
收费全文 | 2730131篇 |
免费 | 187360篇 |
国内免费 | 7978篇 |
专业分类
耳鼻咽喉 | 36262篇 |
儿科学 | 91143篇 |
妇产科学 | 76065篇 |
基础医学 | 381476篇 |
口腔科学 | 73969篇 |
临床医学 | 245792篇 |
内科学 | 540323篇 |
皮肤病学 | 65821篇 |
神经病学 | 221882篇 |
特种医学 | 107519篇 |
外国民族医学 | 819篇 |
外科学 | 407938篇 |
综合类 | 51533篇 |
现状与发展 | 5篇 |
一般理论 | 971篇 |
预防医学 | 208422篇 |
眼科学 | 59985篇 |
药学 | 197862篇 |
10篇 | |
中国医学 | 5475篇 |
肿瘤学 | 152197篇 |
出版年
2019年 | 20745篇 |
2018年 | 32329篇 |
2017年 | 25909篇 |
2016年 | 28914篇 |
2015年 | 33520篇 |
2014年 | 43888篇 |
2013年 | 63317篇 |
2012年 | 88146篇 |
2011年 | 88420篇 |
2010年 | 52833篇 |
2009年 | 52150篇 |
2008年 | 80857篇 |
2007年 | 86227篇 |
2006年 | 88072篇 |
2005年 | 91110篇 |
2004年 | 89502篇 |
2003年 | 83001篇 |
2002年 | 76217篇 |
2001年 | 130697篇 |
2000年 | 132250篇 |
1999年 | 113426篇 |
1998年 | 31662篇 |
1997年 | 28102篇 |
1996年 | 28434篇 |
1995年 | 27623篇 |
1994年 | 25284篇 |
1993年 | 23577篇 |
1992年 | 88950篇 |
1991年 | 85762篇 |
1990年 | 83157篇 |
1989年 | 80327篇 |
1988年 | 73498篇 |
1987年 | 71980篇 |
1986年 | 67393篇 |
1985年 | 63863篇 |
1984年 | 47276篇 |
1983年 | 39902篇 |
1982年 | 23124篇 |
1981年 | 20505篇 |
1979年 | 41620篇 |
1978年 | 29053篇 |
1977年 | 24515篇 |
1976年 | 22556篇 |
1975年 | 24551篇 |
1974年 | 29040篇 |
1973年 | 27387篇 |
1972年 | 25776篇 |
1971年 | 23985篇 |
1970年 | 22072篇 |
1969年 | 21280篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
M Hernanz-Schulman 《Radiology》1991,181(1):9-11
Fifty-five children (34 boys, 21 girls; age range, 1 day to 18 years) with increased echogenicity of the renal medullary pyramids at ultrasound evaluation were identified. The clinical diagnoses associated with hyperechoic medullary pyramids could be separated based on the presence or absence of hypercalciuria. Patients with drug-induced hypercalciuria included 10 infants treated with furosemide, two treated with long-term steroid therapy, and one treated with excessive amounts of vitamin D. Other clinical conditions associated with hypercalciuria included renal tubular acidosis (n = 10), Bartter syndrome (n = 5), hyperparathyroidism (n = 3), Williams syndrome (n = 2) and medullary sponge kidney (n = 2). Ten children with transient renal insufficiency and three with sickle cell disease had normal urine calcium concentration. Isolated disease entities accounted for the remainder of cases. A specific diagnosis can usually be made in a patient with hyperechoic renal medullary pyramids by using a systematic clinical approach that includes evaluation of patient age, serum and urine calcium concentration, and renal function. 相似文献
992.
S Amartur Z P Liang F Boada E M Haacke 《Journal of magnetic resonance imaging : JMRI》1991,1(6):721-724
The authors present an improvement to a sigma-filter extrapolation method for the reconstruction of magnetic resonance (MR) images from symmetric discrete Fourier data. By making use of the phase information in the image data, the proposed method can overcome the data inconsistency problem of the original method for handling MR image data with large phase variations, such as those obtained in gradient-echo pulse sequences. Reconstruction results show that its performance is comparable with that of the modified complex sigma-filter method proposed previously to handle the inconsistency problem. However, the new approach has the advantage of reducing computation time by a factor of two with use of a sigma filter applied to real instead of complex images. It is expected that this method will be more practical for use in clinical MR imaging systems. 相似文献
993.
K Mahmood M N Chowdhury E A Ayoola I A Mofleh R S Rashed F Z Faleh 《Tropical gastroenterology》1991,12(4):188-191
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture. 相似文献
994.
995.
We sought to determine whether there are indirect costs of teaching in Canadian hospitals. To examine cost differences between teaching and nonteaching hospitals we estimated two cost functions: cost per case and cost per patient-day (dependent variables). The independent variables were number of beds, occupancy rate, teaching ratio (number of residents and interns per 100 beds), province, urbanicity (the population density of the county in which the hospital was situated) and wage index. Within each hospital we categorized a random sample of patient discharges according to case mix and severity of illness using age and standard diagnosis and procedure codes. Teaching ratio and case severity were each highly correlated positively with the dependent variables. The other variables that led to higher costs in teaching hospitals were wage rates and number of beds. Our regression model could serve as the basis of a reimbursement system, adjusted for severity and teaching status, particularly in provinces moving toward introducing case-weighting mechanisms into their payment model. Even if teaching hospitals were paid more than nonteaching hospitals because of the difference in the severity of illness there should be an additional allowance to cover the indirect costs of teaching. 相似文献
996.
M H Eijgelshoven E R De Kloet D T Van den Berg P L Van Giersbergen 《European journal of pharmacology》1991,205(2):183-189
Evidence indicates that endogenous opioid peptides and glucocorticoids participate in the control of cardiovascular regulation during hemorrhagic shock. In the present study, we investigated a possible interaction between brain opioid peptides and adrenal corticosteroids regarding the control of arterial pressure during hemorrhage. The bleeding volumes required to lower arterial pressure to 80, 60 and 40 mmHg were studied in anesthetized sham-operated (SHAM) and adrenalectomized (ADX) rats. I.c.v. administration of 10 micrograms of naloxone resulted in a significant increase in the bleeding volume required to lower arterial pressure from 60 to 40 mmHg in SHAM animals, whereas no effect of naloxone was observed in ADX animals. Replacement therapy with a 100% corticosterone pellet (100 mg, s.c.), but not with a 12.5% corticosterone pellet (12.5 mg corticosterone and 87.5 mg cholesterol, s.c.), resulted in an effect of naloxone on the bleeding volume in ADX animals. The effect of replacement therapy could be inhibited by i.c.v. pretreatment with the synthetic glucocorticoid receptor antagonist, RU38486 (100 ng). These data suggest that (1) opioid mechanisms are involved in the regulation of blood pressure during hemorrhage, and (2) occupancy of glucocorticoid receptors is required for naloxone to exert its hemodynamic effect during hemorrhagic hypotension in ADX rats. 相似文献
997.
Circulating immune complexes in pre-eclampsia. 总被引:3,自引:0,他引:3
Serum samples from 20 non-pregnant women, 30 women with normal pregnancy and 50 women with pregnancy associated with pre-eclampsia were tested for circulating immune complexes using the polyethyleneglycol precipitation method. A highly significant positive correlation was found between circulating immune complexes and severe pre-eclampsia (BP greater than 140/90 mm Hg, albuminuria greater than 0.25 g/l). In contrast to this the difference in immune complex levels between non-pregnant subject, normal pregnancy cases and patients with mild pre-eclampsia was not statistically significant. A significant positive correlation was found between the level of circulating immune complexes and the severity of albuminuria. These findings suggest that circulating immune complexes, though not seeming to play an aetiological role in pre-eclampsia may very well be involved in its pathogenesis. 相似文献
998.
F M Burkle 《Emergency Medicine Clinics of North America》1991,9(1):87-105
Existing triage algorithms consider, for the most part, only the primary casualty with physical trauma. Algorithms fail to appreciate the primary, secondary, or tertiary neuropsychiatric casualty. Research advances on neuropsychiatric casualties must link with the mandates of emergency medical services and disaster management to improve triage sensitivity and specificity. Early recognition and management of neuropsychiatric casualties will diminish the potential for long-term consequences. Expanded triage algorithm supplements are proposed to improve the recognition of those victims at risk. 相似文献
999.
The authors suggest additional criteria evidencing inflammations in the gallbladder and colloid stability of the bile: bile acid absorption and cholesterol sedimentation coefficients. Derivation of these coefficients is based on biochemical examination of the bile with measurements of bile acid, cholesterol, and bilirubin concentrations in both portions. The results of examinations of 99 subjects evidence the diagnostic value and specificity of the characteristics, and availability of this method for clinical practice. 相似文献
1000.
P Brennan D Johnson S Rider N Cone M Goldman A Buckpitt H Chung 《Biopharmaceutics & drug disposition》1991,12(7):547-556
The dermal absorption of niclosamide, a drug shown to prevent Schistosomiasis by blocking the dermal penetration of cercariae, has been examined in Sinclair minipigs and rats. Radioactivity in the urine and feces collected daily for 7 days after application of 14C-niclosamide accounted for less than 2 per cent and 10 per cent of the labelled compound applied to pig and rat skin, respectively. Approximately 20 per cent of the radioactivity from the dose solution was recovered on the skin excised from the area of application in both minipigs and rats. No radioactivity was detected in organs removed from the pig 7 days after application of radiolabelled drug while less than 6 per cent of the dose could be accounted for in the rat organs/carcass. Radioactivity in swine blood, removed 0.5, 1, 2, 4 and at 24 h intervals after dosing, was at or below three times background in all of the samples. Total recovery of the applied radioactivity was 78 per cent in pigs and 57 per cent in rats. These studies indicate that niclosamide is very poorly absorbed after dermal application. The results are consistent with earlier comparative studies showing that dermal penetration of xenobiotics in rats is generally higher than in swine. 相似文献