全文获取类型
收费全文 | 3460篇 |
免费 | 217篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 238篇 |
妇产科学 | 41篇 |
基础医学 | 320篇 |
口腔科学 | 66篇 |
临床医学 | 204篇 |
内科学 | 1056篇 |
皮肤病学 | 57篇 |
神经病学 | 151篇 |
特种医学 | 87篇 |
外国民族医学 | 1篇 |
外科学 | 686篇 |
综合类 | 66篇 |
一般理论 | 1篇 |
预防医学 | 105篇 |
眼科学 | 130篇 |
药学 | 188篇 |
中国医学 | 7篇 |
肿瘤学 | 294篇 |
出版年
2023年 | 36篇 |
2022年 | 62篇 |
2021年 | 144篇 |
2020年 | 78篇 |
2019年 | 101篇 |
2018年 | 151篇 |
2017年 | 104篇 |
2016年 | 140篇 |
2015年 | 96篇 |
2014年 | 169篇 |
2013年 | 205篇 |
2012年 | 261篇 |
2011年 | 261篇 |
2010年 | 163篇 |
2009年 | 143篇 |
2008年 | 211篇 |
2007年 | 203篇 |
2006年 | 202篇 |
2005年 | 201篇 |
2004年 | 118篇 |
2003年 | 131篇 |
2002年 | 93篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 28篇 |
1998年 | 22篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 16篇 |
1988年 | 30篇 |
1987年 | 22篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 20篇 |
1983年 | 12篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有3717条查询结果,搜索用时 0 毫秒
11.
M Clerici A Sarin R L Coffman T A Wynn S P Blatt C W Hendrix S F Wolf G M Shearer P A Henkart 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(25):11811-11815
In vitro T-cell receptor-induced programmed cell death in both activated T cells from human immunodeficiency virus-seronegative (HIV-) donors and resting T cells from HIV+ donors was substantially influenced by cytokines. Addition of exogenous recombinant "type 1" lymphokines interferon gamma and interleukin 2 (IL-2), as well as the macrophage-produced IL-12, which favor cell-mediated T-cell responses, blocks both systems of T-lymphocyte programmed cell death. In contrast, the "type 2" lymphokines IL-4 and IL-10, which favor antibody responses, either had no effect or enhanced these systems of in vitro T-cell programmed cell death. A role for endogenously produced cytokines was suggested by the inhibition of T-cell receptor-mediated death by antibodies against IL-4 and IL-10 and its enhancement by anti-IL-12 in cultures containing monocytes. These results demonstrate that the functional properties of type 1 and type 2 cytokine classes may be further extended to include their effects on T-cell programmed cell death and their possible role in the pathogenesis of HIV infection. 相似文献
12.
This article reviews the concept of affective lability and suggests that new models are needed to characterize the relationship between affective states such as affective lability, impulsivity, and suicidal behavior. The association of affective lability, impulsivity, and suicidal behavior is most relevant to understanding the risk of suicide in individuals with borderline personality disorder. The relationship between affective lability and suicide might be explained as 1) a form of bipolarity, 2) a form of impulse dyscontrol, 3) a quantitative disorder of affect, or 4) an environmental reactivity. Our opinion of the relevant literature suggests that a quantitative disorder of affect accompanied by the inability to control these affects are the essential components leading to the risk of suicidal behavior. Characterizing the dyscontrol and high intensity of affect leads to a reconceptualization of depression in patients with borderline personality disorder and to a re-examination of the causal chain of events leading to suicidal behavior. The implications for clinical practice resulting from the proposed model are discussed. 相似文献
13.
Rakesh Jalali Ashwini Budrukkar Rajiv Sarin Dayananda S Sharma 《Radiotherapy and oncology》2005,74(1):37-44
BACKGROUND AND PURPOSE: To report local control and follow up outcome data of high precision conformal radiotherapy in childhood brain tumours. MATERIALS AND METHODS: Between December 1999 and December 2002, 26 children (17 boys and 9 girls, median age 11.5 years) with incompletely excised or recurrent benign and low-grade brain tumours [13 craniopharyngiomas, 11 low-grade gliomas (LGG) and 2 others] were treated with three-dimensional (3D) conformal radiotherapy (CRT) (12 patients) and stereotactic conformal radiotherapy (SCRT) (14 patients). Gross tumour volume (GTV) included neuro-imaging based visible tumour and/or resected tumour bed. Clinical target volume (CTV) consisted of GTV+ 5 mm margin and planning target volume (PTV) consisted of additional 5 mm margin for CRT and 2 mm for SCRT. Treatment was delivered with 3-9 conformal fixed fields to a median dose of 54 Gy/30 fractions. RESULTS: The actuarial 2 and 3 year disease free and overall survival was 96 and 100%, respectively (median follow up: 25 months, range 12-47 months). Radiological follow up available in 25 patients revealed complete response in 1, partial regression in 10, stable disease in 13 and progression in 1 patient (within the CTV). One patient with craniopharyngioma on a routine imaging revealed a mild asymptomatic cyst enlargement, which resolved with conservative management. A patient with chiasmatic glioma developed cystic degeneration and hydrocephalus 9 months after SCRT requiring cyst drainage and placement of a ventriculoperitoneal shunt. CONCLUSION: High-precision conformal techniques delivering irradiation to a computer generated target volume employing 7-10 mm 3D margins beyond the visible tumour and/or resected tumour bed appear to be safe in children with incompletely resected or recurrent benign and low-grade brain tumours, based on these data. 相似文献
14.
The demand for lightweight, high-modulus, and temperature-resistant materials for aerospace and other high-temperature applications has contributed to the development of ceramic fibers that exhibit most of the favorable properties of monolithic ceramics. This review demonstrates preceramic-based polymer fiber spinning and fiber classifications. We discuss different types of fiber spinning and the advantages of each. Tuning the preceramic polymer chemical properties, molar mass, functional chemistry influences, and incorporation with fillers are thoroughly investigated. Further, we present the applications of preceramic-based polymer fibers in different fields including aerospace, biomedical, and sensor applications. This concise review summarizes recent developments in preceramic fiber chemistry and essential applications. 相似文献
15.
Digant Gupta Carolyn A Lammersfeld Pankaj G Vashi Sadie L Dahlk Christopher G Lis 《Journal of ovarian research》2008,1(1):1-7
Background
Malnutrition is a significant problem in patients with ovarian cancer. The goal of this study was to investigate the prognostic role of Subjective Global Assessment (SGA) in patients with ovarian cancer treated in an integrative cancer treatment setting.Methods
We evaluated a case series of 132 ovarian cancer patients treated at Cancer Treatment Centers of America® from Jan 2001 to May 2006. SGA was used to assess nutritional status at baseline. Using SGA, patients were classified as well nourished (SGA A), moderately malnourished (SGA B) or severely malnourished (SGA C). Kaplan Meier method was used to calculate survival. Cox proportional hazard models were constructed to evaluate the prognostic effect of SGA independent of other factors.Results
Of 132 patients, 24 were newly diagnosed while 108 had received prior treatment. 15 had stage I disease at diagnosis, 8 stage II, 85 stage III and 17 stage IV. The median age at presentation was 54.4 years (range 25.5 – 82.5 years). 66 patients were well-nourished (SGA A), 35 moderately malnourished (SGA B) and 31 severely malnourished (SGA C). Well nourished patients had a median survival of 19.3 months (95% CI: 14.1 to 24.5), moderately malnourished 15.5 months (95% CI: 5.8 to 25.1), and severely malnourished 6.7 months (95% CI: 4.1 to 9.3); the difference being statistically significant (p = 0.0003). Multivariate Cox modeling, after adjusting for stage at diagnosis and prior treatment history found that moderately malnourished and severely malnourished status were associated with a relative risk of 2.1 (95% CI: 1.2 to 3.6, p = 0.008) and 3.4 (95% CI: 1.9 to 5.8, p < 0.001) respectively as compared to well nourished status.Conclusion
Univariate and multivariate survival analyses found that low SGA scores (i.e. well-nourished status) are associated with better survival outcomes. This study lends support to the role of aggressive nutritional intervention in improving patient outcomes in cancer care. 相似文献16.
Abhinandan Kumar Vatika Soni Pardeep Singh Aftab Aslam Parwaz Khan Mohammed Nazim Satyabrata Mohapatra Vipin Saini Pankaj Raizada Chaudhery Mustansar Hussain Mohamed Shaban Hadi M. Marwani Abdullah M. Asiri 《RSC advances》2022,12(22):13609
The selection of a facile, eco-friendly, and effective methodology is the need of the hour for efficient curing of the COVID-19 virus in air, water, and many food products. Recently, semiconductor-based photocatalytic methodologies have provided promising, green, and sustainable approaches to battle against viral activation via the oxidative capabilities of various photocatalysts with excellent performance under moderate conditions and negligible by-products generation as well. Considering this, recent advances in photocatalysis for combating the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are inclusively highlighted. Starting from the origin to the introduction of the coronavirus, the significant potential of photocatalysis against viral prevention and -disinfection is discussed thoroughly. Various photocatalytic material-based systems including metal-oxides, metal-free and advanced 2D materials (MXenes, MOFs and COFs) are systematically examined to understand the mechanistic insights of virus-disinfection in the human body to fight against COVID-19 disease. Also, a roadmap toward sustainable solutions for ongoing COVID-19 contagion is also presented. Finally, the challenges in this field and future perspectives are comprehensively discussed involving the bottlenecks of current photocatalytic systems along with potential recommendations to deal with upcoming pandemic situations in the future.Photocatalysts are green, eco-friendly, clean and sustainable and could be a solution to combat COVID-19 because of potential features of various types of metal oxides against viral inactivation via the generation of reactive oxidative species. 相似文献
17.
18.
19.
20.