全文获取类型
收费全文 | 20794篇 |
免费 | 435篇 |
国内免费 | 493篇 |
专业分类
耳鼻咽喉 | 598篇 |
儿科学 | 1250篇 |
妇产科学 | 388篇 |
基础医学 | 2080篇 |
口腔科学 | 713篇 |
临床医学 | 1088篇 |
内科学 | 4929篇 |
皮肤病学 | 371篇 |
神经病学 | 1530篇 |
特种医学 | 559篇 |
外科学 | 3595篇 |
综合类 | 172篇 |
一般理论 | 10篇 |
预防医学 | 2056篇 |
眼科学 | 492篇 |
药学 | 1211篇 |
中国医学 | 202篇 |
肿瘤学 | 478篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 52篇 |
2021年 | 79篇 |
2020年 | 79篇 |
2019年 | 99篇 |
2018年 | 123篇 |
2017年 | 53篇 |
2016年 | 122篇 |
2015年 | 68篇 |
2014年 | 106篇 |
2013年 | 50篇 |
2012年 | 1970篇 |
2011年 | 2234篇 |
2010年 | 496篇 |
2009年 | 249篇 |
2008年 | 1721篇 |
2007年 | 1970篇 |
2006年 | 1735篇 |
2005年 | 1875篇 |
2004年 | 1785篇 |
2003年 | 1711篇 |
2002年 | 1602篇 |
2001年 | 1071篇 |
2000年 | 1572篇 |
1999年 | 719篇 |
1998年 | 80篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1942年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
61.
de la Mora MP Cárdenas-Cachón L Vázquez-García M Crespo-Ramírez M Jacobsen K Höistad M Agnati L Fuxe K 《Neuroscience letters》2005,377(2):101-105
The intercalated islands are intra-amigdaloid clusters of D1 receptor rich GABAergic neurons, which control impulse traffic between the basolateral complex and the central nucleus of the amygdala. As dopaminergic transmission within the amygdala may play a role in anxiety, the effect of the D1 antagonist SCH23390 microinjected mainly close to the rostral intercalated islands in rats was studied, using the White and Black Box test. SCH23390 reduced anxiety by an increase in the latency of the first entry into the black compartment and by an increase in the total time spent in the white compartment of the White and Black Box test, while there was no significant modification of locomotion. It is suggested that blockade of D1 receptors in the rostral intercalated islands may reduce anxiety through a reduction of GABA-mediated dishinibition of the central amygdaloid nucleus. 相似文献
62.
González-Griego M Pentón E Delgado G Pérez-Oliva J Ramos V Izquierdo M García G Levy N Cinza Z Valdivia I Trujillo J Delahanty A 《Investigación clínica》2000,41(4):237-244
The follow-up of HBV markers in selected high infection risk populations, in patients from the hemodialysis and peritoneal dialysis services was used to assess the effectiveness of a special vaccination program. Viral infection markers were studied in prevalence cross sections of the whole population of patients, and also by recording the reports of clinical cases of hepatitis B occurred during that period in those groups of patients. The prevention program consisted of the vaccination of all patients negative to the viral markers and the indication of vaccination for the new cases during the period of the kidney disease, just before the start of the treatment at the hemodialysis unit; besides all the persons susceptible to infection that had already been included in the program, regardless of the stage of the disease. The results show the benefit of the vaccination in these patients, but it is more effective in the period before the treatment with dialysis where there is a lower possibility of being exposed to the virus and the immune system is still competent. Once the program was established, after a follow up o 6 years, there have been no reports of new cases of hepatitis B and the incidence of the disease has been declining. 相似文献
63.
Montes-Rodríguez CJ Alavez S Elder JH Haro R Morán J Prospéro-García O 《Neuroscience letters》2004,360(3):133-136
The human immunodeficiency virus (HIV) induces neuronal death, presumably by apoptosis. This effect may be triggered by the glycoprotein 120 (HIVgp120) released by HIV when infecting a cell, and mediated by tumor necrosis factor alpha (TNF), a pro-inflammatory cytokine. Both molecules, HIVgp120 and TNF, increase sleep when administered acutely in the brain. On the other hand, sleep deprivation increases the levels of several growth factors. In this context, we challenged rats with HIVgp120 or TNF simultaneously with sleep deprivation. Our results indicate that both HIVgp120 and TNF increase neuronal death in the rat cerebral cortex, but not hippocampus, and that this effect is completely prevented by total deprivation of sleep. These results suggest that acute total deprivation of sleep protects against the HIVgp120 and TNF deleterious effects. 相似文献
64.
Several age-related alterations occur at the cellular level in the immune system leading to a decrease in the immune response. The present study was designed to determine the effect of L-carnitine on impaired neutrophil functions of aged rats. For this reason, superoxide anion radical production, chemotaxis and phagocytic activity were studied in the neutrophils obtained from the peripheral blood of young and old rats. We orally gavaged L-carnitine (50 mg/kg b.w. per day) or control vehicle into young (2 months) and aged (24 months) rats for 30 consecutive days. The neutrophils of aged rats exhibited an increase in superoxide anion production and decline in phagocytosis and chemotaxis when compared with that in young rat neutrophils. Superoxide anion production in aged rats was significantly decreased by L-carnitine treatment which was accompanied with a significant enhancement of chemotactic and phagocytic activity being restored to control levels. These findings demonstrated that L-carnitine is capable of restoring the age-related changes of neutrophil functions. 相似文献
65.
66.
Surface chemistry modulates focal adhesion composition and signaling through changes in integrin binding 总被引:10,自引:0,他引:10
Biomaterial surface properties influence protein adsorption and elicit diverse cellular responses in biomedical and biotechnological applications. However, the molecular mechanisms directing cellular activities remain poorly understood. Using a model system with well-defined chemistries (CH3, OH, COOH, NH2) and a fixed density of the single adhesive ligand fibronectin, we investigated the effects of surface chemistry on focal adhesion assembly and signaling. Surface chemistry strongly modulated integrin binding and specificity—5β1 integrin binding affinity followed the pattern OH>NH2=COOH>CH3, while integrin Vβ3 displayed the relationship COOH>NH2OH=CH3. Immunostaining and biochemical analyses revealed that surface chemistry modulates the structure and molecular composition of cell-matrix adhesions as well as focal adhesion kinase (FAK) signaling. The neutral hydrophilic OH functionality supported the highest levels of recruitment of talin, -actinin, paxillin, and tyrosine-phosphorylated proteins to adhesive structures. The positively charged NH2 and negatively charged COOH surfaces exhibited intermediate levels of recruitment of focal adhesion components, while the hydrophobic CH3 substrate displayed the lowest levels. These patterns in focal adhesion assembly correlated well with integrin 5β1 binding. Phosphorylation of specific tyrosine residues in FAK also showed differential sensitivity to surface chemistry. Finally, surface chemistry-dependent differences in adhesive interactions modulated osteoblastic differentiation. These differences in focal adhesion assembly and signaling provide a potential mechanism for the diverse cellular responses elicited by different material properties. 相似文献
67.
68.
We analyzed the kinetics of heart rate (HR) response during incremental treadmill exercise in thirteen master runners (62 +/- 1 yr). The HR/running speed (HR/S) relationship showed the existence of a point of downward deflection (HR(d)) in only approximately 31% of the subjects. Resting echocardiographic evaluations showed similar heart dimensions in all of the subjects. In conclusion, HR does not seem to show a curvilinear response (downward deflection) in most aged athletes. 相似文献
69.
Prediction of postoperative morbidity after lung resection using an artificial neural network ensemble 总被引:4,自引:0,他引:4
OBJECTIVE: To propose an ensemble model of artificial neural networks (ANNs) to predict cardio-respiratory morbidity after pulmonary resection for non-small cell lung cancer (NSCLC). METHODS: Prospective clinical study was based on 489 NSCLC operated cases. An artificial neural network ensemble was developed using a training set of 348 patients undergoing lung resection between 1994 and 1999. Predictive variables used were: sex of the patient, age, body mass index, ischemic heart disease, cardiac arrhythmia, diabetes mellitus, induction chemotherapy, extent of resection, chest wall resection, perioperative blood transfusion, tumour staging, forced expiratory volume in 1s percent (FEV(1)%), and predicted postoperative FEV(1)% (ppoFEV(1)%). The analysed outcome was the occurrence of postoperative cardio-respiratory complications prospectively recorded and codified. The artificial neural network ensemble consists of 100 backpropagation networks combined via a simple averaging method. The probabilities of complication calculated by ensemble model were obtained to the actual occurrence of complications in 141 cases operated on between January 2000 and December 2001 and a receiver operating characteristic (ROC) curve for this method was constructed. RESULTS: The prevalence of cardio-respiratory morbidity was 0.25 in the training and 0.30 in the validation series. The accuracy for morbidity prediction (area under the ROC curve) was 0.98 by the ensemble model. CONCLUSION: In this series an artificial neural network ensemble offered a high performance to predict postoperative cardio-respiratory morbidity. 相似文献
70.
Alvarez M García F Martínez NM Hernández Quero J Louwagie J De Brauwer A Maroto MC 《Journal of medical virology》2004,73(2):151-157
The changes in viral load and CD4(+) count at 3 and 6 months in a group of 166 HIV-infected patients was evaluated. The new therapy was chosen based on the medical history procedures for 70 patients, and in 96 patients it was guided by the partial or complete result of the line probe assay (LiPA) HIV RT and Protease resistance tests. The absolute difference from the baseline of the log viral load at 3 and 6 months was significantly different between the two groups when adjusted for baseline viral load (P < 0.0001) and stayed significant when intention-to-treat analysis was carried out (P < 0.001). The absolute difference of the CD4(+) count was not significantly different when adjusted for baseline CD4(+) (P = 0.854, 3 months; P = 0.06, 6 months). The proportion of patients with a viral load =200 cp/ml in the medical history group (14.5%, 3 months; 15.2%, 6 months) was significantly different from the proportion of responders in the LiPA group (28.7%, 3 months, P = 0.03; 34.7%, 6 months, P = 0.008). In the intention-to-treat population, the difference between the two groups remained significant (P = 0.01). There was no statistical difference between the two groups in terms of adherence (P = 0.88), number of drug failures (P = 0.12) and for the time since starting treatment (in years) (P = 0.48), but there was a significant difference for the number of new drugs in the new regimen (P < 0.0001) and for the pill burden of the treatment (P = 0.0006). A higher antiretroviral HIV treatment success guided by the LiPA HIV genotyping system than that based on the medical history only is reported. Of note, this study reached the same conclusions as previous studies, which all used sequencing. 相似文献