全文获取类型
收费全文 | 1309362篇 |
免费 | 101159篇 |
国内免费 | 1655篇 |
专业分类
耳鼻咽喉 | 16918篇 |
儿科学 | 42363篇 |
妇产科学 | 36340篇 |
基础医学 | 196578篇 |
口腔科学 | 35807篇 |
临床医学 | 124302篇 |
内科学 | 255962篇 |
皮肤病学 | 28077篇 |
神经病学 | 105836篇 |
特种医学 | 48147篇 |
外国民族医学 | 266篇 |
外科学 | 184425篇 |
综合类 | 26557篇 |
现状与发展 | 3篇 |
一般理论 | 628篇 |
预防医学 | 109868篇 |
眼科学 | 28800篇 |
药学 | 96342篇 |
6篇 | |
中国医学 | 2097篇 |
肿瘤学 | 72854篇 |
出版年
2019年 | 11007篇 |
2018年 | 14650篇 |
2017年 | 11161篇 |
2016年 | 12310篇 |
2015年 | 14052篇 |
2014年 | 19350篇 |
2013年 | 29421篇 |
2012年 | 40249篇 |
2011年 | 42728篇 |
2010年 | 24615篇 |
2009年 | 23594篇 |
2008年 | 40034篇 |
2007年 | 42772篇 |
2006年 | 42293篇 |
2005年 | 41308篇 |
2004年 | 39619篇 |
2003年 | 37847篇 |
2002年 | 36782篇 |
2001年 | 57255篇 |
2000年 | 58306篇 |
1999年 | 49180篇 |
1998年 | 13995篇 |
1997年 | 12698篇 |
1996年 | 13045篇 |
1995年 | 12337篇 |
1994年 | 11528篇 |
1993年 | 10757篇 |
1992年 | 39078篇 |
1991年 | 38483篇 |
1990年 | 37255篇 |
1989年 | 36001篇 |
1988年 | 33359篇 |
1987年 | 32714篇 |
1986年 | 31168篇 |
1985年 | 29446篇 |
1984年 | 22461篇 |
1983年 | 19646篇 |
1982年 | 11711篇 |
1979年 | 21359篇 |
1978年 | 15731篇 |
1977年 | 13069篇 |
1976年 | 12147篇 |
1975年 | 13031篇 |
1974年 | 15880篇 |
1973年 | 15600篇 |
1972年 | 14760篇 |
1971年 | 13768篇 |
1970年 | 12974篇 |
1969年 | 12230篇 |
1968年 | 11399篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Gram negative endotoxins play a contributory role in the syndrome which results from over consumption of carbohydrates by horses and ponies. Since the antibiotic polymyxin B exerts a direct anti-endotoxin effect by chemically modifying the active lipid A moiety of endotoxin, it might be expected to protect horses after carbohydrate overload and provide a new therapeutic and experimental tool for this condition. The present study was undertaken to evaluate the effect of polymyxin B on hemostatic, hemodynamic, acid-base, and clinical aspects of the syndrome resulting from carbohydrate overload. Experimentally-induced carbohydrate overload resulted in lactic acidosis, hypercoagulability, hypovolemic shock and lameness. Although there was a slight delay in the onset of clinical signs resulting from experimental carbohydrate overload in treated animals, polymyxin B administered iv at 2.5 mg/kg every 6 hr failed to significantly ameliorate the coagulopathy, acidosis, lameness and shock induced by alimentary carbohydrate overload. 相似文献
992.
993.
A M Cesura M D Galva R Imhof E Kyburz G B Picotti M Da Prada 《European journal of pharmacology》1989,162(3):457-465
This study demonstrated the existence of specific binding sites for [3H]Ro 19-6327 in human platelet membranes. This compound is a novel, time-dependent inhibitor of monoamine oxidase type B (MAO-B) and is structurally closely related to [3H]Ro 16-6491. The density of the sites labelled with high affinity by [3H]Ro 19-6327 was similar to that observed in previous studies with [3H]Ro 16-6491 as ligand. Binding was reversible at 20 degrees C and showed a relatively slow dissociation (t1/2 = 220 min). The dissociation rate was markedly decreased (t1/2 = greater than 24h) at 0 degrees C. MAO-B, but not MAO-A inhibitors, effectively prevented the binding of [3H]Ro 19-6327. Like [3H]Ro 16-6491, [3H]Ro 19-6327 is recognized as a substrate by MAO-B, being eventually deaminated by the enzyme. Since the deaminated aldehyde derivative of Ro 19-6327 did not inhibit MAO-B, a still unidentified reversible adduct, formed at the MAO-B active site, might explain the high potency and selectivity of [3H]Ro 19-6327. Incubation of the radioligand-enzyme complex from platelet and brain membranes with NaBH3CN and acetic acid (to pH 4.5) caused the irreversible incorporation of the radioactivity into a single polypeptide as shown by SDS-PAGE analysis. This polypeptide had a molecular weight identical to that of the MAO-B subunit, i.e. 58,000. The presence of unlabelled MAO-B inhibitors in the incubation mixture prevented the covalent incorporation of [3H]Ro 19-6327. The irreversible MAO-B inhibitor, [3H] pargyline, labelled a protein with a molecular weight identical to the protein labelled by [3H]Ro 19-6327.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
994.
995.
Decreased caloric intake in normal-weight patients with bulimia: comparison with female volunteers 总被引:1,自引:0,他引:1
H E Gwirtsman W H Kaye E Obarzanek D T George D C Jimerson M H Ebert 《The American journal of clinical nutrition》1989,49(1):86-92
Patients with bulimia (binge-purge syndrome) frequently complain that they consume a very restrictive diet to avoid gaining weight. To investigate this claim, 23 hospitalized bulimic patients were assessed daily for body weight, caloric intake, macronutrient diet content, activity measures, and body composition estimates during weight-stable periods. Bulimic patients ate fewer kilocalories per kilogram body weight (22.1 +/- 4.6 kcal/kg) than did age-matched normal women (29.7 +/- 6.5 kcal/kg) but had similar activity levels and body composition. Clinical variables, such as history of laxative abuse, anorexia, or obesity, and physiological characteristics, such as body weight, activity level, or dietary content, could not account for this difference in caloric consumption. Bulimic patients tended to eat a diet lower in fat and higher in protein than did control subjects. These results agree with observations of increased efficiency of caloric utilization in obese patients and support patient complaints of a tendency to gain weight easily. 相似文献
996.
Efficacy of transdermal clonidine for headache prophylaxis and reduction of narcotic use in migraine patients. A randomized crossover trial 总被引:1,自引:0,他引:1
R C Bredfeldt J E Sutherland J E Kruse 《The Journal of family practice》1989,29(2):153-6; discussion 157-8
Thirty patients completed a double-blind, randomized crossover study utilizing transdermal clonidine and an identical-appearing placebo. Crossover occurred at 6 weeks, with a total study time of 12 weeks. Subjects were asked to record daily in a special diary (1) the presence or absence of headache, (2) duration of headache, (3) severity of headache, and (4) use of pain medication for headache relief. The severity of the headaches was rated from 1 (very mild) to 5 (very severe). Although the subjects reported a decrease in frequency, duration, and intensity of headaches while using the medicated patch, these differences did not reach statistical significance. Nineteen patients subjectively preferred the medicated patch, while five preferred the placebo (P less than .01). During use of the medicated patch, a significant reduction (P = .039) occurred in use of class II narcotics. Three doses of these substances were used by the patients when treated with clonidine, while 34 doses were taken during placebo use. These findings suggest that clonidine might have a role in reduction of parenteral narcotic use in acute pain syndromes. 相似文献
997.
E Griez 《L'Encéphale》1987,13(6):335-339
This paper reviews recent developments in the experimental approach to panic anxiety. Inhalation of carbon dioxide appears to trigger panic attacks in panic disorder patients and agoraphobics. The biological and psychopathological implications of this finding are discussed in the light of recent data on experimental pharmacology of anxiety. 相似文献
998.
999.
G.E. ORLANDINI S. ZECCHI ORLANDINI A.F. HOLSTEIN R. EVANGELISTI and R. PONCHIETTI 《Andrologia》1987,19(3):315-321
The human prostatic urethra has been investigated by means of scanning electron microscopy. On the posterior wall of the urethra, the seminal colliculus with the orifices of the ejaculatory ducts is clearly detectable. The upper portion of the prostatic urethra shows a typical transitional epithelium with large superficial cells of a ruffled appearance. In the lower portion of the organ (underneath the openings of the ejaculatory ducts), the apical pattern of the cells varies considerably. Four main aspects are recognizable: apices provided with microvilli, dome-shaped apices with an almost smooth surface, large apices with labyrinthic microplicae and ciliated apices. Also, apices showing intermediate characteristics can be noted. The functional significance of the morphological patterns as well as the possibility of a transition among the various types of surface structures are discussed. 相似文献
1000.
We isolated hybridoma cells, which secreted monoclonal antibody (MAb) 121 SLE, an IgM showing the following reactivities: (1) by immunodiffusion, MAb 121 SLE and MAb NS 19-9 (a monoclonal antibody directed against a sialylated Lewis(a) antigen called CA 19-9) showed an identical precipitin line with mucin preparation containing this CA 19-9; (2) by immunoradiometric assay, MAb 121 SLE totally inhibited fixation of radiolabelled MAb NS 19-9; (3) by immunoperoxidase, MAb 121 SLE stained the normal gastrointestinal mucosa of Le-positive individuals exclusively, and this staining disappeared after neuraminidase treatment, as observed using MAb NS 19-9. However, the pattern of the staining obtained with MAb 121 SLE differed slightly from that given by MAb 19-9 on the different positive areas of the gastrointestinal mucosae. These differences principally concerned the number of positive epithelial cells and the intensity of their staining; (4) moreover, antibodies against idiotype determinant of NS 19-9 antibody did not react with the antibody 121 SLE. We concluded that MAb 121 SLE is different from the MAb NS 19-9. However, both these antibodies were associated with the same molecular sialylated Lewis(a) structure. 相似文献