全文获取类型
收费全文 | 52228篇 |
免费 | 2467篇 |
国内免费 | 401篇 |
专业分类
耳鼻咽喉 | 510篇 |
儿科学 | 1130篇 |
妇产科学 | 557篇 |
基础医学 | 7005篇 |
口腔科学 | 1067篇 |
临床医学 | 3203篇 |
内科学 | 13114篇 |
皮肤病学 | 1247篇 |
神经病学 | 3952篇 |
特种医学 | 2154篇 |
外科学 | 9035篇 |
综合类 | 242篇 |
一般理论 | 6篇 |
预防医学 | 1366篇 |
眼科学 | 1133篇 |
药学 | 3340篇 |
中国医学 | 185篇 |
肿瘤学 | 5850篇 |
出版年
2023年 | 295篇 |
2022年 | 575篇 |
2021年 | 1044篇 |
2020年 | 554篇 |
2019年 | 759篇 |
2018年 | 1063篇 |
2017年 | 789篇 |
2016年 | 1006篇 |
2015年 | 1096篇 |
2014年 | 1440篇 |
2013年 | 1826篇 |
2012年 | 2901篇 |
2011年 | 3240篇 |
2010年 | 1854篇 |
2009年 | 1646篇 |
2008年 | 2973篇 |
2007年 | 3242篇 |
2006年 | 3237篇 |
2005年 | 3264篇 |
2004年 | 3360篇 |
2003年 | 3386篇 |
2002年 | 3364篇 |
2001年 | 818篇 |
2000年 | 748篇 |
1999年 | 818篇 |
1998年 | 876篇 |
1997年 | 721篇 |
1996年 | 678篇 |
1995年 | 571篇 |
1994年 | 507篇 |
1993年 | 533篇 |
1992年 | 509篇 |
1991年 | 528篇 |
1990年 | 443篇 |
1989年 | 511篇 |
1988年 | 426篇 |
1987年 | 359篇 |
1986年 | 314篇 |
1985年 | 322篇 |
1984年 | 268篇 |
1983年 | 224篇 |
1982年 | 172篇 |
1981年 | 181篇 |
1980年 | 159篇 |
1979年 | 168篇 |
1978年 | 147篇 |
1977年 | 130篇 |
1976年 | 105篇 |
1975年 | 105篇 |
1972年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Fukukawa Y Nakashima C Tsuboi S Niino N Ando F Kosugi S Shimokata H 《The journals of gerontology. Series B, Psychological sciences and social sciences》2004,59(1):P19-P26
In this study, we compared the impact of health problems (HPs) on everyday activities and depressive symptoms between middle-aged and older adults. We also examined what type and source of social interactions moderate the noxious effects of HPs. Longitudinal analyses of data with 1,802 Japanese community-dwelling adults indicated that HPs were significantly related to (a) an increase in depressive symptoms among middle-aged adults and (b) a decline in everyday activities among older adults. The former was buffered by emotional family support, whereas the latter (b) was buffered by instrumental family support and, surprisingly, by negative interactions with family. In contrast, social interactions with other friends and acquaintances did not show any moderating effect. 相似文献
993.
Ahmed T Azam MA Armed N Jamil KM Hassan F Ogura N Tamura H Yokochi T 《Journal of endotoxin research》2004,10(4):223-228
The level of circulating endotoxin was determined in the sera from children hospitalized for treatment of diarrhea at the International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. A significant level of endotoxin was detected in the sera from 23 (54%) of 42 children. On the other hand, in 32 normal controls, endotoxin was below the limits of detection of the assay. Antibiotic and fluid therapy markedly reduced the level of serum endotoxin and improved the general condition of most patients. Non-survivors (n = 5) had higher levels of circulating endotoxin before treatment than survivors (n = 37), suggesting a significant correlation between the serum endotoxin level before treatment and mortality. Malnutrition did not affect the serum endotoxin level in the patients with diarrhea. It was suggested that infection of Gram-negative bacteria might be involved in a significant number of patients with diarrhea in Bangladesh and that endotoxin might play a pathogenic role in those patients. 相似文献
994.
Nogami A Sugiyasu A Tada H Kurosaki K Sakamaki M Kowase S Oginosawa Y Kubota S Usui T Naito S 《Journal of cardiovascular electrophysiology》2008,19(7):681-688
Introduction: Although successful ablation of ventricular tachycardia (VT) is feasible in arrhythmogenic right ventricular cardiomyopathy (ARVC), long-term recurrence is common. The aim of this study was to assess the usefulness of a change in the isolated delayed component (IDC) as an endpoint of the catheter ablation in ARVC.
Methods and Results: Eighteen patients (48 ± 11 years) with ARVC were studied. Detailed endocardial mapping of the right ventricle (RV) was performed during sinus rhythm. IDCs were recorded in 16 patients and the latest IDCs were related to the VT circuit. Catheter ablation was carried out in the areas with the IDCs. At the end of the session, the IDC was electrically dissociated in one, disappeared in five, exhibited second-degree block in one, was significantly delayed (≥50 ms) in three, and remained unchanged in six. The change in the IDC was correlated with the change in the type II/III late potentials in the signal-averaged electrocardiography (ECG) and the inducibility of the clinical VT after the ablation. During a follow-up of 61 ± 38 months, VT recurred in six. The patients with a changed IDC had a significantly lower VT recurrence than those with no IDC or an unchanged IDC (P < 0.02).
Conclusion: In patients with ARVC, (1) the IDCs during sinus rhythm are related to the clinical VT and can be a target for the ablation, (2) a change in the IDC can be used as an endpoint, and (3) qualitative analyses of the serial signal-averaged ECGs may be useful for the long-term follow-up. 相似文献
Methods and Results: Eighteen patients (48 ± 11 years) with ARVC were studied. Detailed endocardial mapping of the right ventricle (RV) was performed during sinus rhythm. IDCs were recorded in 16 patients and the latest IDCs were related to the VT circuit. Catheter ablation was carried out in the areas with the IDCs. At the end of the session, the IDC was electrically dissociated in one, disappeared in five, exhibited second-degree block in one, was significantly delayed (≥50 ms) in three, and remained unchanged in six. The change in the IDC was correlated with the change in the type II/III late potentials in the signal-averaged electrocardiography (ECG) and the inducibility of the clinical VT after the ablation. During a follow-up of 61 ± 38 months, VT recurred in six. The patients with a changed IDC had a significantly lower VT recurrence than those with no IDC or an unchanged IDC (P < 0.02).
Conclusion: In patients with ARVC, (1) the IDCs during sinus rhythm are related to the clinical VT and can be a target for the ablation, (2) a change in the IDC can be used as an endpoint, and (3) qualitative analyses of the serial signal-averaged ECGs may be useful for the long-term follow-up. 相似文献
995.
Liao WL Tsai HC Wang HF Chang J Lu KM Wu HL Lee YC Tsai TF Takahashi H Wagner M Ghyselinck NB Chambon P Liu FC 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(18):6765-6770
Retinoid signaling plays a crucial role in patterning rhombomeres in the hindbrain and motor neurons in the spinal cord during development. A fundamentally interesting question is whether retinoids can pattern functional organization in the forebrain that generates a high order of cognitive behavior. The striatum contains a compartmental structure of striosome (or "patch") and intervening matrix. How this highly complex mosaic design is patterned by the genetic programs during development remains elusive. We report a developmental mechanism by which retinoid receptor signaling controls compartmental formation in the striatum. We analyzed RARbeta(-/-) mutant mice and found a selective loss of striosomal compartmentalization in the rostral mutant striatum. The loss of RARbeta signaling in the mutant mice resulted in reduction of cyclin E2, a cell cycle protein regulating transition from G(1) to S phase, and also reduction of the proneural gene Mash1, which led to defective neurogenesis of late-born striosomal cells. Importantly, during striatal neurogenesis, endogenous levels of retinoic acid were spatiotemporally regulated such that transduction of high levels of retinoic acid through RARbeta selectively expanded the population of late-born striosomal progenitors, which evolved into a highly elaborate compartment in the rostral striatum. RARbeta(-/-) mutant mice, which lacked such enlarged compartment, displayed complex alternations of dopamine agonist-induced stereotypic motor behavior, including exaggeration of head bobbing movement and reduction of rearing activity. RARbeta signaling thus plays a crucial role in setting up striatal compartments that may engage in neural circuits of psychomotor control. 相似文献
996.
Yamazaki T Asanoi H Ueno H Yamada K Takagawa J Kameyama T Hirai T Nozawa T Inoue H 《Clinical and experimental hypertension (New York, N.Y. : 1993)》2005,27(2-3):241-249
The present study was designed to develop a method to continuously measure Holter electrocardiogram (ECG) and physical activity in terms of metabolic costs to examine circadian dynamics of RR intervals and physical activity in patients with heart failure. A total of 7 healthy subjects and 3 heart failure patients performed cardiopulmonary exercise test using four-stage graded treadmill walking at 0% grade to examine whether the acceleration signals in the vertical direction could reflect actual body energy expenditure during physical activity. Then, using this new method, 24-hr monitorings of ECG and physical activity were performed in 24 inpatients with heart failure while they were allowed to walk around freely. Our results showed the integral of rectified acceleration signals was closely correlated with actual metabolic cost in all subjects. Instantaneous changes in heart rate were quite concordant with physical activity. As compared with the asymptomatic patients (n = 12), the symptomatic patients (n = 12) had lower energy expenditure during 8-hr daytime periods but higher mean heart rate. Furthermore, a more prominent ultradian rhythm of circadian changes in heart rate and physical activity was found in 50% of all subjects studied. The simultaneous analysis of Holter ECG and physical activity as the same time series revealed that in patients with heart failure, sympathovagal balance shifted toward sympathotonic conditions and their physical activity could become subject to intrinsic ultradian dynamics of body's homeostasis. 相似文献
997.
Virus-associated hemophagocytic syndrome in an international traveler as a differential diagnosis of SARS 总被引:3,自引:0,他引:3
During the epidemic of severe acute respiratory syndrome in 2003, a 27-year- old Japanese woman presented a high fever and acute respiratory distress with pulmonary infiltrates after traveling to a high-risk area. An alternative diagnosis was made as Epstein-Barr virus-associated hemophagocytic syndrome, based on the proliferation of macrophages with hemophagocytosis in the bone marrow and Epstein-Barr viral marker profiles. Virus-associated hemophagocytic syndrome in an international traveler should be included in the differential diagnosis of severe acute respiratory syndrome. 相似文献
998.
The Wnt signaling pathway has recently been demonstrated to play an important role in regulation of bone formation. LRP5 is thought to signal through the canonical Wnt pathway. In humans, LRP5 loss-of-function mutations lead to low bone mass with fractures, while LRP5 gain-of-function mutations lead to high bone mass, thus identifying LRP5 as an important regulator of bone mass. Patients with sclerosteosis have a severe skeletal disorder with progressive bone overgrowth due to a loss of function of the SOST gene, which implicates its role as a suppressor of bone formation. Recent study revealed that SOST is a BMP antagonist with unique ligand specificity, negatively regulating bone formation by repressing BMP-induced osteoblast differentiation or function or both. 相似文献
999.
High plasma fibrinogen level is associated with poor clinical outcome in DIC patients 总被引:1,自引:0,他引:1
Wada H Mori Y Okabayashi K Gabazza EC Kushiya F Watanabe M Nishikawa M Shiku H Nobori T 《American journal of hematology》2003,72(1):1-7
We measured the plasma level of fibrinogen in 560 patients with disseminated intravascular coagulation (DIC) and evaluated its relationship with outcome and with other hemostatic markers. Forty-seven percent of patients had >200 mg/dL of plasma fibrinogen and 24% had <100 mg/dl of plasma fibrinogen, suggesting that plasma fibrinogen level is not a sensitive marker for DIC. In our analysis of outcome and plasma fibrinogen levels, the rate of death was high in leukemia/lymphoma patients with high fibrinogen concentration, but no significant difference in outcome was observed in relation to plasma fibrinogen concentration in non-leukemia/lymphoma patients with DIC. Among patients with leukemia/lymphoma, the frequency of organ failure was markedly high in patients with high plasma levels of fibrinogen. Among patients without leukemia/lymphoma, the frequency of organ failure increased concomitantly with the increase in plasma fibrinogen levels. The international normalized ratio was significantly increased in leukemia/lymphoma patients with low fibrinogen. FDP levels were slightly increased in patients with low fibrinogen. Platelet count was significantly low in patients without leukemia/lymphoma with high fibrinogen. DIC score increased concomitantly with the reduction in plasma fibrinogen levels. Plasma levels of thrombomodulin and tissue factor were significantly high in patients with high fibrinogen levels. Plasma levels of antiplasmin and plasminogen were significantly decreased in patients with low fibrinogen. Plasma levels of plasmin plasmin-inhibitor complex and tissue type plasminogen activator/plasminogen activator inhibitor-1 complex (PAI-I) were significantly higher in patients with low fibrinogen than in those with high fibrinogen. Plasma levels of PAI-I and IL-6 were significantly higher in patients with high fibrinogen than in those with low fibrinogen. Patients with high fibrinogen levels showed less activation of secondary fibrinolysis, which might explain the occurrence of organ failure and poor outcome. 相似文献
1000.
We report two cases of septic pulmonary embolism associated with periodontitis. Chest CT revealed multiple nodular shadows with features characteristic of septic pulmonary embolism in both patients. Both patients had toothache, fever, and chest pain, and showed findings of periodontitis at initial presentation. Antimicrobial agents combined with dental surgery were successful in treatment. While septic pulmonary embolism from the lesions of periodontitis appears to be rare, periodontitis remains important in the differential diagnosis of septic pulmonary embolism. 相似文献