全文获取类型
收费全文 | 1268563篇 |
免费 | 95227篇 |
国内免费 | 1595篇 |
专业分类
耳鼻咽喉 | 16365篇 |
儿科学 | 41191篇 |
妇产科学 | 35048篇 |
基础医学 | 189954篇 |
口腔科学 | 34786篇 |
临床医学 | 118534篇 |
内科学 | 248649篇 |
皮肤病学 | 27328篇 |
神经病学 | 102372篇 |
特种医学 | 46906篇 |
外国民族医学 | 265篇 |
外科学 | 179039篇 |
综合类 | 25814篇 |
现状与发展 | 3篇 |
一般理论 | 575篇 |
预防医学 | 105251篇 |
眼科学 | 28128篇 |
药学 | 92841篇 |
7篇 | |
中国医学 | 2023篇 |
肿瘤学 | 70306篇 |
出版年
2018年 | 13664篇 |
2017年 | 10490篇 |
2016年 | 11411篇 |
2015年 | 13195篇 |
2014年 | 18143篇 |
2013年 | 27756篇 |
2012年 | 37924篇 |
2011年 | 40342篇 |
2010年 | 23230篇 |
2009年 | 22408篇 |
2008年 | 38042篇 |
2007年 | 40714篇 |
2006年 | 40251篇 |
2005年 | 39443篇 |
2004年 | 37868篇 |
2003年 | 36236篇 |
2002年 | 35129篇 |
2001年 | 56085篇 |
2000年 | 57089篇 |
1999年 | 48134篇 |
1998年 | 13451篇 |
1997年 | 12259篇 |
1996年 | 12678篇 |
1995年 | 11953篇 |
1994年 | 11143篇 |
1993年 | 10429篇 |
1992年 | 38226篇 |
1991年 | 37698篇 |
1990年 | 36473篇 |
1989年 | 35287篇 |
1988年 | 32727篇 |
1987年 | 32048篇 |
1986年 | 30537篇 |
1985年 | 28800篇 |
1984年 | 21960篇 |
1983年 | 19206篇 |
1982年 | 11383篇 |
1981年 | 10331篇 |
1979年 | 20957篇 |
1978年 | 15403篇 |
1977年 | 12797篇 |
1976年 | 11850篇 |
1975年 | 12813篇 |
1974年 | 15591篇 |
1973年 | 15366篇 |
1972年 | 14514篇 |
1971年 | 13561篇 |
1970年 | 12788篇 |
1969年 | 12067篇 |
1968年 | 11234篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
C Cislaghi E Negri C La Vecchia F Levi 《Revue d'épidémiologie et de santé publique》1990,38(3):237-243
A method of graphic representation of time factors in cancer mortality is presented, based on different tonalities of grey applied to the surface of the matrix defined by various age-specific rates. It is illustrated using mortality data from cancers of the mouth or pharynx, oesophagus, larynx and lung in Italian and Swiss males. Progressively more complex regression surface equations are defined, on the basis of two independent variables (age and cohort) and a dependent one (each age-specific rate). General patterns of trends were thus identified, showing important similarities in cohort and period effects, but also noticeable differences in time-related factors in mortality from various neoplasms of the upper digestive and respiratory tract. For instance, there were declines in mortality from cancers of the mouth or pharynx in the oldest age groups, whereas rates were appreciably upwards at younger and middle age, particularly in Italy. Likewise, cancers of the oesophagus and, chiefly, of the larynx were substantially increasing, on a cohort basis, in oldest Italian males. Temporal pattern for laryngeal cancer in Italy was similar to that of lung cancer, thus suggesting that (cigarette) smoking has a greater impact on this cancer site as compared with alcohol. However, it is difficult to explain, on this basis alone, the totally diverging pattern for cancer of the larynx (downwards) and of the lung (upwards) observed among older Swiss males. These examples indicate that trend surface models are a useful summary guide to illustrate and understand the general patterns of age, period and cohort effects in cancer mortality. 相似文献
993.
Pattern of postprandial carbohydrate metabolism and effects of portal and peripheral insulin delivery 总被引:4,自引:0,他引:4
E J Kryshak P C Butler C Marsh A Miller D Barr K Polonsky J D Perkins R A Rizza 《Diabetes》1990,39(2):142-148
The importance of portal insulin delivery in the regulation of postprandial carbohydrate metabolism is uncertain. To address this question, three groups of dogs were studied: one group in which pancreatic venous drainage was transected and reanastomosed (portal insulin delivery), one in which the pancreatic drainage was transected and anastomosed to the inferior vena cava (peripheral insulin delivery), and one that received only a sham operation. Plasma insulin was greater (P less than 0.05) during peripheral insulin delivery than in either the portal or sham groups, respectively, before and after meal ingestion. On the other hand, C-peptide concentrations did not differ between groups, resulting in a higher (P less than 0.001) insulin to C-peptide ratio in the peripheral group. This indicated that the hyperinsulinemia in the peripheral group was due to decreased insulin clearance rather than increased insulin secretion. Isotopically determined splanchnic uptake of ingested glucose, postprandial suppression of hepatic glucose release, incorporation of CO2 into glucose (a qualitative measure of gluconeogenesis), and total-body glucose uptake were virtually identical in all groups. Similarly, plasma lipid, beta-hydroxybutyrate, and lactate concentrations did not differ between groups. Our data indicate that, despite differences in systemic insulin concentration, portal and peripheral insulin delivery comparably regulate hepatic and extrahepatic carbohydrate metabolism after meal ingestion. 相似文献
994.
The limited contact dynamic compression plate (LC-DCP) 总被引:5,自引:0,他引:5
S. M. Perren K. Mane O. Pohler M. Predieri S. Steinemann E. Gautier 《Archives of orthopaedic and trauma surgery》1990,109(6):304-310
Summary To realize the new concept of biological internal fixation the limited contact dynamic compression plate was developed. It minimizes vascular damage to the plated bone segment. It should lead to a more versatile and efficient application of internal fixation using plates. 相似文献
995.
Desferrioxamine (DFO) metabolism and its pharmacokinetics were studied in a swine model using high-performance liquid chromatography. DFO and three iron-binding metabolites occurred in plasma. Interindividual differences in pharmacokinetics and metabolism were observed. Urine analysis in 4 pigs showed three iron-binding metabolites. The mean percent dose excreted in urine in the form of the parent drug was 45 +/- 10% and 10 +/- 2% (means +/- SD) in the form of metabolites. Of the total amount of the parent drug infused, 3 h after initiation, 87% was in the form of DFO, whereas 13% was present as the DFO-iron III complex which represented 45 mg of urinary iron elimination. The described DFO infusion protocol provides for sufficient DFO to chelate significant amounts of ferric iron in excess of normal levels, thus allowing experimental studies of iron chelation in a variety of disease states. 相似文献
996.
Between January and June 1988, a survey of 7516 people in aged care facilities in the Auckland region (99.4% response rate) was undertaken to ascertain the extent and provision of care for elderly people requiring ongoing care in order to make comparisons with other centres in New Zealand. Information was gathered about their ability to perform various activities of daily living by staff members who completed a structured precoded and pretested questionnaire for each resident or patient. Overall levels of dependency were also assessed as part of the questionnaire: 13% were assessed as requiring long stay hospital care, 48% had moderate or appreciable dependency, and the remainder had some dependency (23%) or none at all (16%). Almost one quarter (23%) of the 5213 residents in old people's homes were rated as apparently independent. Of people in religious and welfare residential homes, 38% were rated as independent whereas in commercial rest homes 12% of people were classified in this way. This high level of apparent independence in religious and welfare homes is the main aspect in which the Auckland long term care scene is distinct from other regions in the country. 相似文献
997.
BRIAN J. STOCKMAN CAROL A. BANNOW ROBERT M. MICELI MICHAEL E. DEGRAAF H. DAVID FISCHER CLARK W. SMITH 《Chemical biology & drug design》1995,45(1):11-16
Epitope libraries provide a method to identify peptide ligands for antibodies, receptors or other binding proteins. As such, they provide a powerful tool to rapidly identify lead ligands in the drug discovery process. In an attempt to correlate structural information with the results from peptide screening, we have used NMR spectroscopy of peptide/antibody complexes to demonstrate that core residues identified through a two-stage selection process undergo a larger structural change upon binding antibody than do positions in the peptide amenable to a variety of side chains. The model system used was the M2 monoclonal antibody/Flag? octapeptide epitope system. We have analyzed two peptides: Ac-Asp-Tyr-Lys-Leu-Gly-Asp-Asp-Leu-NH2 (peptide l), which contains several non-core positions randomized, and Ac-Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Leu-NH2 (peptide 2), which closely corresponds to the original Flag? sequence. Enrichment of the peptides with 15N facilitated the investigation by permitting spectral editing of the peptide resonances in the presence of antibody. For peptide 1 the absolute shifts for the free vs. Fab-bound peptide were found to be largest for the amide groups of Asp-1 and Asp-6, in agreement with classification of these residues as critical by the phage display library selection process. For peptide 2 the largest absolute shifts were observed for Asp-1 and Asp-4, with the other aspartic acid residues also showing significant but smaller changes. © Munksgaard 1995. 相似文献
998.
C. AZCONA L. CASTRO E. CRESPO M. JIMÉNEZ & L. SIERRASESÚMAGA 《Alimentary pharmacology & therapeutics》1996,10(4):577-586
Background : Malnutrition is very frequent in childhood cancer. Its main cause is inadequate intake for energy demands owing to lack of appetite. Megestrol acetate is a synthetic progestin that has been used for reversing anorexia in adult cancer.
Objectives : To assess megestrol acetate efficacy and side-effects in treating anorexia in childhood cancer.
Methods : Thirty-five children with solid tumours were receiving antitumour therapy. Nutritional assessment was by anthropometry. Megestrol acetate efficacy was assessed by evaluating grade of appetite, energy intake and well-being. Side-effects were evaluated by means of clinical history, physical examination, lipid profile, coagulation tests and cortisol rhythm.
Results : When compared to baseline all the anthropometric measurements increased ( P <0.05) from the first month of megestrol acetate therapy, as well as appetite and energy intake. No significant side-effects were found.
Conclusion : Megestrol acetate therapy is a powerful appetite stimulant which led to weight gain, composed of both fat mass and fat-free mass. Megestrol acetate is well tolerated, with few and mild side-effects. If megestrol acetate therapy is started at the onset of anorexia, the use of more expensive, invasive and complicated techniques of nutritional support may be avoided. 相似文献
Objectives : To assess megestrol acetate efficacy and side-effects in treating anorexia in childhood cancer.
Methods : Thirty-five children with solid tumours were receiving antitumour therapy. Nutritional assessment was by anthropometry. Megestrol acetate efficacy was assessed by evaluating grade of appetite, energy intake and well-being. Side-effects were evaluated by means of clinical history, physical examination, lipid profile, coagulation tests and cortisol rhythm.
Results : When compared to baseline all the anthropometric measurements increased ( P <0.05) from the first month of megestrol acetate therapy, as well as appetite and energy intake. No significant side-effects were found.
Conclusion : Megestrol acetate therapy is a powerful appetite stimulant which led to weight gain, composed of both fat mass and fat-free mass. Megestrol acetate is well tolerated, with few and mild side-effects. If megestrol acetate therapy is started at the onset of anorexia, the use of more expensive, invasive and complicated techniques of nutritional support may be avoided. 相似文献
999.
Harold T. Kyriazi George E. Carvell Joshua C. Brumberg Daniel J. Simons 《Brain research》1996,712(2):325
Extracellular single-unit recordings were made in somatosensory cortical barrels of fentanyl-sedated rats. Whiskers were deflected singly or in paired combinations. lontophoretically-applied (−)-baclofen disproportionately reduced weak responses, and phaclofen disproportionately increased them, resulting in more tightly focused or more broadly focused receptive fields, respectively. Both drugs had only minor effects on surround inhibition. In light of previous findings, we conclude that GABAA and GABAB mechanisms both act to enhance spatial contrast, but that the former plays a much greater role in enhancing temporal resolution. 相似文献
1000.
G. Chalkiadakis M. Menton E. Wiest R. Schrage 《Archives of gynecology and obstetrics》1993,254(1-4):1243-1244
Ohne Zusammenfassung 相似文献