全文获取类型
收费全文 | 1840990篇 |
免费 | 128994篇 |
国内免费 | 4081篇 |
专业分类
耳鼻咽喉 | 24295篇 |
儿科学 | 60956篇 |
妇产科学 | 49878篇 |
基础医学 | 262265篇 |
口腔科学 | 52985篇 |
临床医学 | 162405篇 |
内科学 | 359603篇 |
皮肤病学 | 42675篇 |
神经病学 | 144595篇 |
特种医学 | 71459篇 |
外国民族医学 | 266篇 |
外科学 | 280513篇 |
综合类 | 39865篇 |
现状与发展 | 4篇 |
一般理论 | 562篇 |
预防医学 | 131258篇 |
眼科学 | 44093篇 |
药学 | 133831篇 |
7篇 | |
中国医学 | 4768篇 |
肿瘤学 | 107782篇 |
出版年
2021年 | 13877篇 |
2019年 | 14644篇 |
2018年 | 22339篇 |
2017年 | 17197篇 |
2016年 | 19344篇 |
2015年 | 22042篇 |
2014年 | 29416篇 |
2013年 | 42508篇 |
2012年 | 59772篇 |
2011年 | 62053篇 |
2010年 | 36693篇 |
2009年 | 33868篇 |
2008年 | 58127篇 |
2007年 | 62115篇 |
2006年 | 62620篇 |
2005年 | 60271篇 |
2004年 | 58083篇 |
2003年 | 55412篇 |
2002年 | 53513篇 |
2001年 | 96133篇 |
2000年 | 98024篇 |
1999年 | 80918篇 |
1998年 | 21035篇 |
1997年 | 18354篇 |
1996年 | 18183篇 |
1995年 | 17402篇 |
1994年 | 15928篇 |
1993年 | 14648篇 |
1992年 | 59315篇 |
1991年 | 57174篇 |
1990年 | 54879篇 |
1989年 | 52550篇 |
1988年 | 47716篇 |
1987年 | 46508篇 |
1986年 | 43725篇 |
1985年 | 41412篇 |
1984年 | 30504篇 |
1983年 | 25844篇 |
1982年 | 14534篇 |
1979年 | 26774篇 |
1978年 | 18488篇 |
1977年 | 15700篇 |
1976年 | 14544篇 |
1975年 | 15563篇 |
1974年 | 18674篇 |
1973年 | 17888篇 |
1972年 | 16612篇 |
1971年 | 15385篇 |
1970年 | 14251篇 |
1969年 | 13287篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The onset of the sporadic Creutzfeldt-Jakob disease is usually characterized by dementia or neurological symptoms. We are reporting the case of a 31 year-old man with a sporadic Creutzfeldt-Jakob disease characterized by a schizophrenia-like onset. The schizophrenic symptoms developed for sixteen months before the neurological symptoms appeared. The psychiatric onset of the present case was linked with the early age of onset and the long duration of the disease and could have been influenced by polymorphism of the codon 129 of the prion protein gene (PRNP) and a type of pathological prion protein (PrPres). 相似文献
92.
93.
A Trakic F Liu H Sanchez Lopez H Wang S Crozier 《Magnetic resonance in medicine》2007,57(6):1119-1130
The switching of magnetic field gradient coils in magnetic resonance imaging (MRI) inevitably induces transient eddy currents in conducting system components, such as the cryostat vessel. These secondary currents degrade the spatial and temporal performance of the gradient coils, and compensation methods are commonly employed to correct for these distortions. This theoretical study shows that by incorporating the eddy currents into the coil optimization process, it is possible to modify a gradient coil design so that the fields created by the coil and the eddy currents combine together to generate a spatially homogeneous gradient that follows the input pulse. Shielded and unshielded longitudinal gradient coils are used to exemplify this novel approach. To assist in the evaluation of transient eddy currents induced within a realistic cryostat vessel, a low-frequency finite-difference time-domain (FDTD) method using the total-field scattered-field (TFSF) scheme was performed. The simulations demonstrate the effectiveness of the proposed method for optimizing longitudinal gradient fields while taking into account the spatial and temporal behavior of the eddy currents. 相似文献
94.
95.
Summary The third-stage larvae of Daniconema anguillae Moravec et K?ie, 1987 are found in the eels fins caught from Dringis Lake (Lithuanian National park). The morphology of these
larvae is briefly described. 相似文献
96.
Chukwuka C Okafor Hana Haleem-Smith Patrice Laqueriere Paul A Manner Rocky S Tuan 《Journal of orthopaedic research》2006,24(3):461-473
Continual loading and articulation cycles undergone by metallic (e.g., titanium) alloy arthroplasty prostheses lead to liberation of a large number of metallic debris particulates, which have long been implicated as a primary cause of periprosthetic osteolysis and postarthroplasty aseptic implant loosening. Long-term stability of total joint replacement prostheses relies on proper integration between implant biomaterial and osseous tissue, and factors that interfere with this integration are likely to cause osteolysis. Because multipotent mesenchymal stem cells (MSCs) located adjacent to the implant have an osteoprogenitor function and are critical contributors to osseous tissue integrity, when their functions or activities are compromised, osteolysis will most likely occur. To date, it is not certain or sufficiently confirmed whether MSCs endocytose titanium particles, and if so, whether particulate endocytosis has any effect on cellular responses to wear debris. This study seeks to clarify the phenomenon of titanium endocytosis by human MSCs (hMSCs), and investigates the influence of endocytosis on their activities. hMSCs incubated with commercially pure titanium particles exhibited internalized particles, as observed by scanning electron microscopy and confocal laser scanning microscopy, with time-dependent reduction in the number of extracellular particles. Particulate endocytosis was associated with reduced rates of cellular proliferation and cell-substrate adhesion, suppressed osteogenic differentiation, and increased rate of apoptosis. These cellular effects of exposure to titanium particles were reduced when endocytosis was inhibited by treatment with cytochalasin D, and no significant effect was seen when hMSCs were treated only with conditioned medium obtained from particulate-treated cells. These findings strongly suggest that the biological responses of hMSCs to wear debris are triggered primarily by the direct endocytosis of titanium particulates, and not mediated by secreted soluble factors. In this manner, therapeutical approaches that suppress particle endocytosis could reduce the bioreactivity of hMSCs to particulates, and enhance long-term orthopedic implant prognosis by minimizing wear-debris periprosthethic osteolysis. 相似文献
97.
98.
O Schouten J H H van Laanen E Boersma R Vidakovic H H H Feringa M Dunkelgrün J J Bax J Koning H van Urk D Poldermans 《European journal of vascular and endovascular surgery》2006,32(1):21-26
OBJECTIVE: To evaluate the effect of statins on aneurysm growth in a group of consecutive patients under surveillance for infrarenal aortic aneurysms (AAA). MATERIALS AND METHODS: All patients (59 statin users, 91 non-users) under surveillance between January 2002 and August 2005 with a follow-up for aneurysm growth of at least 12 months and a minimum of three diameter evaluations were retrospectively included in the analysis. Multiple regression analysis, weighted with the number of observations, was performed to test the influence of statins on AAA growth rate. RESULTS: During a median period of 3.1 (1.1-13.1) years the overall mean aneurysm growth rate was 2.95+/-2.8 mm/year. Statin users had a 1.16 mm/year lower AAA growth rate compared to non-users (95% CI 0.33-1.99 mm/year). Increased age was associated with a slower growth (-0.09 mm/year per year, p = 0.003). Female gender (+1.82 mm/year, p = 0.008) and aneurysm diameter (+0.06 mm/year per mm, p = 0.049) were associated with increased AAA growth. The use of non-steroidal anti-inflammatory drugs, chronic lung disease, or other cardiovascular risk factors were not independently associated with AAA growth. CONCLUSIONS: Statins appear to be associated with attenuation of AAA growth, irrespective of other known factors influencing aneurysm growth. 相似文献
99.
The vagal nerve as a link between the nervous and immune system in the instance of polymicrobial sepsis 总被引:5,自引:0,他引:5
Wolfram Kessler Tobias Traeger Alexandra Westerholt Friederike Neher Marlene Mikulcak Antje Müller Stefan Maier Claus-Dieter Heidecke 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》2006,391(2):83-87
Background The role of the vagal nerve in the autonomic nervous system is widely well known. Recently, an additional function was revealed
serving as a connector between the nervous and immune system. This connection is called the “cholinergic inflammatory pathway.”
Through stimulation of the acetylcholine receptors located upon the macrophages, the “unspecific” immune system can be directly
influenced.
Methods The vagal nerve was completely transected directly posterior to its passage through the diaphragm. The effect of complete
vagotomy was analyzed using a murine model of polymicrobial peritonitis (colon ascendens stent peritonitis, CASP). Survival
and clinical course of vagotomized or sham-operated mice were analyzed in the CASP model.
Results After CASP surgery, vagotomy led to a significantly increased mortality (64.7%) in comparison to sham-vagotomized animals
(34%). No difference in the bacterial load of various tissues (lung, liver, spleen, blood, lavage fluid, and kidney) from
septic animals with or without vagotomy was observed. Vagotomized animals reveal elevated serum cytokine levels (TNF, IL-6,
IL-10, and MCP-1) 20 h after the induction of polymicrobial peritonitis.
Conclusion The vagal nerve is therefore an important modulator of the immune system.
W. Kessler and T. Traeger contributed equally to this work
Best of Forum Papers presented at the Annual Meeting of the German Society of Surgery, 2–5 May 2006, Berlin, Germany 相似文献
100.