全文获取类型
收费全文 | 72459篇 |
免费 | 3870篇 |
国内免费 | 312篇 |
专业分类
耳鼻咽喉 | 1459篇 |
儿科学 | 2398篇 |
妇产科学 | 1650篇 |
基础医学 | 9420篇 |
口腔科学 | 2458篇 |
临床医学 | 4995篇 |
内科学 | 17725篇 |
皮肤病学 | 2416篇 |
神经病学 | 5950篇 |
特种医学 | 1557篇 |
外国民族医学 | 1篇 |
外科学 | 8772篇 |
综合类 | 481篇 |
一般理论 | 21篇 |
预防医学 | 7206篇 |
眼科学 | 1324篇 |
药学 | 5098篇 |
中国医学 | 478篇 |
肿瘤学 | 3232篇 |
出版年
2023年 | 478篇 |
2022年 | 1119篇 |
2021年 | 2785篇 |
2020年 | 1307篇 |
2019年 | 2394篇 |
2018年 | 2808篇 |
2017年 | 1696篇 |
2016年 | 1621篇 |
2015年 | 1838篇 |
2014年 | 2733篇 |
2013年 | 3770篇 |
2012年 | 5310篇 |
2011年 | 5657篇 |
2010年 | 3160篇 |
2009年 | 2680篇 |
2008年 | 4026篇 |
2007年 | 4182篇 |
2006年 | 3854篇 |
2005年 | 3887篇 |
2004年 | 3503篇 |
2003年 | 3219篇 |
2002年 | 2937篇 |
2001年 | 1648篇 |
2000年 | 1776篇 |
1999年 | 1469篇 |
1998年 | 485篇 |
1997年 | 424篇 |
1996年 | 330篇 |
1995年 | 299篇 |
1994年 | 248篇 |
1993年 | 189篇 |
1992年 | 542篇 |
1991年 | 444篇 |
1990年 | 428篇 |
1989年 | 326篇 |
1988年 | 323篇 |
1987年 | 291篇 |
1986年 | 254篇 |
1985年 | 243篇 |
1984年 | 154篇 |
1983年 | 152篇 |
1982年 | 118篇 |
1981年 | 132篇 |
1980年 | 102篇 |
1979年 | 148篇 |
1978年 | 113篇 |
1974年 | 108篇 |
1973年 | 79篇 |
1971年 | 91篇 |
1969年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 860 毫秒
231.
232.
F Villas Martínez F J Contreras J M López Caza?a M C López Serrano F Martínez Alzamora 《Journal of investigational allergology & clinical immunology》1992,2(5):258-262
The efficacy of the new nonsedating antihistamines loratadine and cetirizine was compared in a randomized, single-blind, crossover, controlled study with that of the classical antihistamines cyproheptadine and ketotifen in seven patients with primary acquired cold urticaria (ACU). The patients received each of the four drugs for 14 consecutive days with a 7-day interval between drugs. We evaluated clinical symptomatology, adverse effects, minimum time of cold contact stimulation required to induce an immediate coalescent wheal (CSTT), and inhibition of histamine-induced wheal response. Both loratadine and cetirizine showed suppression of symptoms with infrequent adverse effects. Important side-effects were observed in patients receiving cyproheptadine. Improvement in CSTT was statistically significant for all drugs compared with baseline values, without differences among them. The histamine-induced skin test was significantly inhibited by all antihistamines. Wheal reductions were 34.6% for loratadine and 50.9% for cetirizine. This study suggests that both loratadine and cetirizine may be effective in the treatment of primary ACU. 相似文献
233.
Abnormalities of thirst regulation in patients with chronic renal failure on hemodialysis. 总被引:3,自引:0,他引:3
A Martinez-Vea C García J Gaya F Rivera J A Oliver 《American journal of nephrology》1992,12(1-2):73-79
To determine whether thirst mechanisms are altered in nondiabetic patients with chronic renal failure on hemodialysis, 4 patients with an average weight gain between dialysis sessions of more than 5% of dry body weight (group I), 5 patients with less than 3% weight gain (group II), and a group of 6 healthy subjects (group III) were submitted to infusion of hypertonic saline. After infusion the subjects had free access to water. Thirst was evaluated by visual analogue rating scales. Despite similar increments of effective plasma osmolality during saline infusion, patients of group I were thirstier than groups II and III (p less than 0.005 and p less than 0.01, respectively). Changes in thirst ratings were similar in groups II and III. Osmotic thresholds for thirst onset were similar in groups II and III (288.9 +/- 8.5 and 289.8 +/- 3.4 mosm/kg, respectively), but lower in group I (277.6 +/- 7.6 mosm/kg). Nevertheless, great variations were observed in the latter group. Thus, 2 patients showed thresholds for thirst within the normal range, whereas the others had low osmolar thresholds for thirst and baseline plasma osmolalities and high basal thirst scores. During the drinking period, the patients of group I drank more (14.2 +/- 2.8 ml/kg) than those of groups II (5.3 +/- 1.6 ml/kg; p less than 0.02) and III (10.2 +/- 1.6 ml/kg; n.s.) The plasma levels of angiotensin II in uremic patients were higher than in healthy subjects, although there were no differences between groups I and II and no correlation between basal angiotensin II levels and the interdialytic weight gain.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
234.
235.
M I Arranz Pe?a E Saenz Lope 《Zeitschrift für klinische Chemie und klinische Biochemie》1988,26(11):791-793
A nitrogen-specific gas-chromatographic method is described for the quantitative analysis of soluphylline without the need for derivatization or evaporation of solvent, and using only 50 microliters of serum. The analysis is performed isothermally on a silicone stationary phase, 2% SP 2250 DA (Supelco). After a single neutral extraction with ethyl acetate containing the internal standard (beta-hydroxypropyl theophylline), an aliquot of the organic solvent is injected directly into the gas chromatograph. The detector sensitivity (least measurable amount) for soluphylline was 1 ng. 相似文献
236.
Two new cases of prostatic blue nevus are studied with routine histological, immunohistochemical and ultrastructural methods. Both cases showed a chronic lower urinary tract obstruction due to a benign prostatic hyperplasia with spindle-shaped stromal cells loaded with melanin pigment. These cells were positive for S-100 and negative for HMB-45 antibodies, being, to the best of our knowledge, the first time that this antibody has been tested in prostatic pigmented lesions. The electron-microscopy study was performed in the first case, confirming the nature of these pigmented cells as melanocytes derived from the neural crest showing melanosomes in all the stages of differentiation and without complete basal cell membrane. The histogenesis of pigmented lesions of the prostate and the differences between blue nevus and melanosis are discussed, and the literature is reviewed. 相似文献
237.
Excitatory amino acids may cause neuronal damage and death in cerebral hypoxia and ischemia, through the activation of different subtypes of glutamate receptors, in particular of the
(NMDA) receptor. In the present work, the effect of hypoxia on the component of the field excitatory postsynaptic potential (fepsp) mediated by the NMDA receptor was studied in the hippocampal CA1 area of the rat. A period of 15 min of hypoxia induced virtual abolition of the NMDA receptor-mediated fepsp and a 94.8 ± 0.7% maximal decrease in the fepsp. A period of 3 min of hypoxia induced a 89.3 ± 12.3% maximal decrease in the NMDA receptor-mediated component of the fepsp and only a 50.8 ± 11.5% maximal decrease in the fepsp. Both periods of hypoxia thus induced a more pronounced depression of the NMDA receptor-mediated component of the fepsp than of the fepsp. We found that 48.5 ± 9.1% decrease (about half of the total decrease) in the NMDA receptor-mediated fepsp, and 51.6 ± 19.6% decrease (approximately all decrease) in the fepsp induced by hypoxia (3 min) were reversed in the presence of the selective adenosine A1 receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) (50 nM), and thus likely to be mediated by endogenous adenosine, through the activation of adenosine A1 receptors. On the other hand, under the conditions we assumed to be normoxic in our slices, DPCPX (50 nM) induced a much larger increase in the amplitude of the NMDA receptor-mediated fepsp compared to the increase in the fepsp, which suggest that endogenous adenosine is inhibiting predominantly the NMDA receptor-mediated fepsp under these conditions. Hypoxia markedly decreases the NMDA receptor-mediated fepsp in the hippocampal CA1 area. The contribution of endogenous adenosine to the inhibition of the NMDA receptor-mediated fepsp may be fundamental for its neuroprotective effects. 相似文献
238.
F. J. Barbado J. J. Vázquez J. M. Pe?a F. Arnalich J. Ortiz-Vázquez 《Postgraduate medical journal》1992,68(805):884-887
Comparison was made of the aetiology and methods of diagnosis in two series of patients meeting the classic criteria of pyrexia of unknown origin during 1968-1981 and during 1982-1989 seen in the Department of Internal Medicine at La Paz University Hospital, Madrid, Spain. There was a statistically significant decrease in the percentage of infections and an increase in neoplasms and connective tissue disorders in the second series. The percentage of patients diagnosed by laparatomy was similar in both series but the diagnosis yield at laparotomy was greater in the second period. Pyrexia of unknown origin continues to be a condition which can defy clinical expertise in in spite of advances in diagnostic techniques. 相似文献
239.
J. Sanchez Burson J. Graña Gil M. Rosales Rodriguez A. Atanes Sandoval C. Alonso Blanco F. Galdo Fernandez 《Clinical rheumatology》1992,11(2):261-264
Summary We have studied the characteristics of arthritis present in 32 patients with Behçet's disease (BD), and how this arthritis is related to the HLA markers class I. 84% of the patients presented arthritis, the most common being monoarthritis as the initial presentation, and oligoarthritis in subsequent episodes. In 63% of the cases, the development was in episodes of acute/subacute arthritis. We found statistically significant association between antigens B-5 and B-51, and the group with BD, with a relative risk of 3.89 and 4.71 respectively. The attempt to relate markers B-5, B-51 and B-27 to the presence of arthritis as well as to its manifestation and further development was not conclusive. 相似文献
240.
J L Martínez Sande A Amaro Cendón E Blanco Labrador M Pérez Rodríguez A Sánchez Prieto C Iglesias Carre?o M Gil de la Pe?a 《Revista espa?ola de cardiología》1992,45(8):545-548
A 32-year old woman, with endocarditis caused by Streptococcus mitis, and systolic murmur is presented. The Doppler examination was found a systolic gradient of 150 mmHg. Aortography showed a multiple membranous supravalvular aortic stenosis, with aneurysmal dilatation of the left main coronary artery and circumflex artery, associated with bicuspid aortic valve and mild aortic insufficiency. The patient died suddenly by cardiac arrest in stand by to cardiac surgery. Anatomic comprobation was not possible. The coronary artery anomalies associated with the supravalvular aortic stenosis syndrome are reviewed. 相似文献