全文获取类型
收费全文 | 2392321篇 |
免费 | 180020篇 |
国内免费 | 12301篇 |
专业分类
耳鼻咽喉 | 32113篇 |
儿科学 | 75996篇 |
妇产科学 | 66175篇 |
基础医学 | 336337篇 |
口腔科学 | 64817篇 |
临床医学 | 219190篇 |
内科学 | 462837篇 |
皮肤病学 | 54095篇 |
神经病学 | 188199篇 |
特种医学 | 92249篇 |
外国民族医学 | 735篇 |
外科学 | 354145篇 |
综合类 | 68196篇 |
现状与发展 | 27篇 |
一般理论 | 717篇 |
预防医学 | 178749篇 |
眼科学 | 55364篇 |
药学 | 181548篇 |
123篇 | |
中国医学 | 11383篇 |
肿瘤学 | 141647篇 |
出版年
2021年 | 22437篇 |
2019年 | 21437篇 |
2018年 | 28956篇 |
2017年 | 22867篇 |
2016年 | 25170篇 |
2015年 | 29437篇 |
2014年 | 40421篇 |
2013年 | 56449篇 |
2012年 | 77241篇 |
2011年 | 82197篇 |
2010年 | 48702篇 |
2009年 | 45287篇 |
2008年 | 73681篇 |
2007年 | 77933篇 |
2006年 | 79019篇 |
2005年 | 76218篇 |
2004年 | 71094篇 |
2003年 | 68205篇 |
2002年 | 65362篇 |
2001年 | 120231篇 |
2000年 | 123561篇 |
1999年 | 103626篇 |
1998年 | 28995篇 |
1997年 | 26116篇 |
1996年 | 25662篇 |
1995年 | 24177篇 |
1994年 | 21987篇 |
1993年 | 20340篇 |
1992年 | 76889篇 |
1991年 | 73652篇 |
1990年 | 71380篇 |
1989年 | 68213篇 |
1988年 | 62290篇 |
1987年 | 60574篇 |
1986年 | 56858篇 |
1985年 | 53771篇 |
1984年 | 40023篇 |
1983年 | 33736篇 |
1982年 | 19666篇 |
1979年 | 35323篇 |
1978年 | 24388篇 |
1977年 | 20971篇 |
1976年 | 19052篇 |
1975年 | 20484篇 |
1974年 | 24300篇 |
1973年 | 23418篇 |
1972年 | 22209篇 |
1971年 | 20460篇 |
1970年 | 19179篇 |
1969年 | 18129篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
P. A. Milligan P. E. McGill C. W. Howden A. W. Kelman B. Whiting 《European journal of clinical pharmacology》1993,45(6):507-512
Summary A randomised crossover study was performed in subjects with rheumatoid arthritis (or other arthropathies) to investigate if any alteration in the steady pharmacokinetics of the NSAID piroxicam (a drug which is extensively metabolised via cytochrome P450) or its major metabolites occurred as a result of coadministering either cimetidine or nizatidine.Twelve females and 2 males with mean age, weight, and albumin concentrations of 58 years, 61 kg, and 40 g·L–1 respectively, completed the study. Comparisons were made between the following parameters: plasma piroxicam AUCs [AUC0-24(P)], plasma 5-hydroxypiroxicam AUCs [AUC0-24(5-OHP)], the ratio of these i.e. AUC0-24(5-OHP):AUC0-24(p), the % piroxicam daily dose excreted in urine as 5-hydroxypiroxicam (before and after glucuronidase incubation); and the mean of the steady state trough piroxicam, and 5-hydroxypiroxicam concentrations (obtained during each study phase in addition to the wash-out period).A statistically significant difference as a result of initiating either cimetidine or nizatidine was obtained only for the ratio AUC0-23(5-OHP):AUC0-24(P). This was indicative of a weak potential to inhibit piroxicam hydroxylation.No clinically significant alteration in the steady state pharmacokinetics of piroxicam occurred in these subjects as a result of cimetidine or nizatidine coadministration. Consequently it is unlikely that any adverse events would arise from these combinations. 相似文献
992.
David A. Hughes Graham C. Smith Joyce E. Davidson Anna V. Murphy T. James Beattie 《Pediatric nephrology (Berlin, Germany)》1996,10(4):445-447
. Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome
(D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques.
Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst
of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly
elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral
blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral
blood neutrophil.
Received August 17, 1995; received in revised form and accepted November 27, 1995 相似文献
993.
994.
Dysregulated Fas and Bcl-2 expression leading to enhanced apoptosis in T cells of multiple myeloma patients 总被引:3,自引:1,他引:2
Massaia M; Borrione P; Attisano C; Barral P; Beggiato E; Montacchini L; Bianchi A; Boccadoro M; Pileri A 《Blood》1995,85(12):3679-3687
We have previously reported the presence of activated (HLA-DR+) T cells in multiple myeloma (MM) patients. These cells produce high amounts of interleukin (IL)-2 and interferon (IFN)-gamma and generate a potent antiplasma cell activity after appropriate in vitro stimulation, but they are unable in vivo to hold in check the disease. Activated T cells are highly susceptible to apoptosis, a form of programmed cell death involved in the modulation of immune responses and regulated by molecules such as Fas (CD95) and bcl-2. The aim of this study was to determine the expression of Fas and bcl-2 antigens and the susceptibility to apoptosis in T cells of MM patients. Fas+ cells were significantly higher, whereas bcl-2+ cells were significantly lower in MM patients than in the controls. MM patients with the highest number of HLA-DR+ T cells showed the highest Fas and the lowest bcl-2 expression. Two-color cytofluorometric analysis confirmed in individual cells that HLA-DR+ T cells coexpressed Fas and lacked bcl-2. Susceptibility to apoptosis was then investigated to evaluate the consequence of dysregulated Fas and bcl-2 expression. The percentage of apoptotic cells after incubation in medium alone (spontaneous apoptosis) or in the presence of methylprednisolone (MP) or anti-Fas monoclonal antibody (triggered apoptosis) was significantly higher in MM and mainly restricted to HLA-DR+ T cells. Spontaneous apoptotosis was reverted by exogenous IL-2. In conclusion, MM T cells have a dysregulated expression of Fas and bcl-2 antigens that is associated with an enhanced susceptibility to apoptosis. These data may unravel a novel mechanism by which activated MM T cells are weakened in their ability to exert an effective antitumor activity in vivo. 相似文献
995.
996.
The introduction of new diagnostic tools for neuroimaging has resulted in the early recognition of congenital brain tumors. In the present report we describe a personal series of 39 children and an International Multicenter Series of 876 children with brain tumors, in whom the diagnosis was obtained during the first 12 months of life. Most of the tumors were located within the supratentorial compartment. In spite of a relatively high operative mortality, surgery still appears to be the more effective therapy. Radiotherapy in this age group is of a scarce value, due to the vulnerability of the infantile brain. At the present time, chemotherapy still plays a controversial role. 相似文献
997.
I K Shkhvatsabaia A N Kravchenko P V Avdonin M Iu Men'shikov A A Nekrasova 《Kardiologiia》1988,28(5):72-77
Platelet activation factor (PAF)-, ADP and vasopressin-induced increments of platelet Ca2+ concentration were measured by quin-2 in 64 patients with essential hypertension and 16 normal donors. Basal concentration of free Ca2+ was 87 +/- 4 nM in donors, 106 +/- 5 nM in patients with labile hypertension (LH) and 122 +/- 6 nM in those with stable hypertension (SH) (p less than 0.01). PAF, ADP and vasopressin, added to platelets, increased [Ca]in by 448 +/- 58, 397 +/- 66, and 277 +/- 50 nM, respectively, in the donors, by 473 +/- 57, 479 +/- 54 and 195 +/- 32 nM, in LH patients, and by 607 +/- 85, 584 +/- 73 and 245 +/- 41 nM in SH patients. There were no significant variations between the three samples, using the ANOVA test. In 20 patients, whose both parents had essential hypertension, [Ca]in increment was 738 +/- 8 nM for PAF, 682 +/- 90 nM for ADP, and 320 +/- 61 nM for vasopressin. In 19 patients, who admitted to no essential hypertension in the family, these parameters were significantly lower: 310 +/- 40 nM for PAF, 389 +/- 61 nM for ADP, and 147 +/- 26 nM for vasopressin. The demonstrated changes may be making an important contribution to the maintenance of elevated vascular tone and provide an evidence in favor of a genetically-predetermined EH variety. 相似文献
998.
A prognosis of patients with a curative resected advanced cancer of the lower gastric region was worse than that of the other region of the stomach. The 5 year survival rate was only 47.3%. One of the main reasons was that a rate of lymph node recurrence was higher. In this point of view, we studied on lymphatic flow of the lower gastric region using an activated carbon particle (CH40). Lymph nodes were stained black soon after the injection of CH40 into the lower gastric wall at laparotomy. The black stained rate of an each regional lymph node was as follows. 3. 58%, 4. 17%, 5. 50%, 6. 25%, 1. 21%, 7. 58%, 8. 83%, 9. 58%, 11. 17% and 12. 33% in case of injection into the greater curvature and and 4. 31%, 6. 100%, 8. 25%, 9. 25%, 14V and 56% in case of injection into the lesser curvature. The stained rate was relatively high in 12 and 14V lymph node which we had not routinely dissected. The rates of lymph nodes stained black were related to those of cancer metastasis. The results suggest that lymphadenectomy of 12 for the cancer at the lesser curvature and that of 14V for the cancer at the greater curvature might make a prognosis of lower gastric cancer better. 相似文献
999.
Confounders contributing to the reported associations of coffee or caffeine with disease 总被引:2,自引:0,他引:2
G B Schreiber M Robins C E Maffeo M N Masters A P Bond D Morganstein 《Preventive medicine》1988,17(3):295-309
The role of caffeine or coffee in causing or promoting the incidence of serious disease is equivocal. Two design factors may account for the discrepancies in reported findings on the effects of coffee drinking: (a) imprecision of measurement and (b) confounding variables. A study of 2,714 white U.S. adults disclosed that, of 32 risk factors analyzed by linear and logistic regression, only sex and cigarette smoking were found to be important potential confounders of caffeine and coffee intake. Partial R2 values of the other 30 risk factors were relatively small and were inconsistent for each sex. It is unlikely that any of these factors could explain any of the reported associations between caffeine or coffee consumption and certain diseases. However, certain weak associations with caffeine or coffee intake should be included in the study design when they are known to be risk factors of a disease under investigation. These factors for men are dietary fat intake, vitamin C intake, and body mass index; and for women are vitamin use, alcohol intake, stress, and perceived health status. 相似文献
1000.
This study investigates the contribution of body fat stores on the age-associated increase in serum cholesterol and triglyceride levels. Percentage of body fat was measured by hydrostatic weighing, and serum cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels were determined in a sample of 472 healthy men and women ages 18-50 years. In both sexes, body fat mass was significantly correlated with serum cholesterol (r = 0.21 in men and r = 0.24 in women, P less than 0.01) and triglyceride (r = 0.33 in men and r = 0.24 in women, P less than 0.01) levels. After adjustment for the association between age and serum cholesterol, no correlation was observed between body fat mass and serum cholesterol (r = 0.01 in men and r = 0.09 in women). After correction for age, serum triglyceride levels remained significantly correlated with body fat mass (r = 0.26 and r = 0.17 in men and women, respectively, P less than 0.05). As body fat also increases with age, the possibility that a partial correlation coefficient procedure eliminated a portion of the age effect mediated by an age-related increase in fat, was addressed by performing further analyses. Within each sex subsample two sets of analyses were performed on (a) three groups of subjects individually paired for age but with different levels of body fat stores, and (b) three groups of subjects paired for the amount of body fat but differing in age.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献