全文获取类型
收费全文 | 6109篇 |
免费 | 445篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 46篇 |
儿科学 | 204篇 |
妇产科学 | 349篇 |
基础医学 | 910篇 |
口腔科学 | 117篇 |
临床医学 | 453篇 |
内科学 | 1287篇 |
皮肤病学 | 82篇 |
神经病学 | 521篇 |
特种医学 | 162篇 |
外科学 | 786篇 |
综合类 | 114篇 |
一般理论 | 8篇 |
预防医学 | 587篇 |
眼科学 | 139篇 |
药学 | 402篇 |
中国医学 | 18篇 |
肿瘤学 | 383篇 |
出版年
2023年 | 54篇 |
2022年 | 98篇 |
2021年 | 213篇 |
2020年 | 94篇 |
2019年 | 149篇 |
2018年 | 187篇 |
2017年 | 119篇 |
2016年 | 129篇 |
2015年 | 159篇 |
2014年 | 192篇 |
2013年 | 263篇 |
2012年 | 421篇 |
2011年 | 406篇 |
2010年 | 210篇 |
2009年 | 167篇 |
2008年 | 331篇 |
2007年 | 324篇 |
2006年 | 320篇 |
2005年 | 310篇 |
2004年 | 263篇 |
2003年 | 240篇 |
2002年 | 230篇 |
2001年 | 69篇 |
2000年 | 87篇 |
1999年 | 73篇 |
1998年 | 50篇 |
1997年 | 56篇 |
1996年 | 45篇 |
1995年 | 42篇 |
1994年 | 50篇 |
1993年 | 43篇 |
1992年 | 71篇 |
1991年 | 62篇 |
1990年 | 55篇 |
1989年 | 64篇 |
1988年 | 57篇 |
1987年 | 50篇 |
1986年 | 52篇 |
1985年 | 50篇 |
1984年 | 49篇 |
1983年 | 44篇 |
1982年 | 49篇 |
1981年 | 35篇 |
1980年 | 33篇 |
1979年 | 41篇 |
1978年 | 32篇 |
1977年 | 31篇 |
1976年 | 29篇 |
1975年 | 29篇 |
1973年 | 28篇 |
排序方式: 共有6568条查询结果,搜索用时 15 毫秒
141.
Adedayo O. Oduola Judith B. Olojede Isaac O. Oyewole Olubunmi A. Otubanjo Taiwo S. Awolola 《Parasitology research》2013,112(10):3433-3439
Mosquito samples were collected from rural and urban communities in three selected major towns in Southwestern Nigeria to determine the impact of urbanization on the diversity and abundance of Anopheles species associated with malaria transmission in human habitations. A total of ten Anopheles species were identified in the rural communities, while eight Anopheles species were identified in the urban communities. Out of the ten Anopheles species identified, only four species, Anopheles gambiae (Giles), Anopheles funestus (Giles), Anopheles moucheti (Evans), and Anopheles nili (Theobald), were established to be vectors of malaria occurring in greater than 50 % of the rural communities. Only A. gambiae occurred in all the urban communities, while the other three major vectors occurred in not more than 20 % of the urban communities. Margalef's and Shannon–Wiener indices showed that diversity and species richness were higher in the rural compared to the urban. Comprehensive information on malaria vector abundance and diversity in rapidly changing communities is an important tool in planning and implementing successful vector control programs. 相似文献
142.
Isaac J. Pence Christine M. OBrien Laura E. Masson Anita Mahadevan-Jansen 《Biomedical optics express》2021,12(2):852
In vivo Raman spectroscopy has been utilized for the non-invasive, non-destructive assessment of tissue pathophysiology for a variety of applications largely through the use of fiber optic probes to interface with samples of interest. Fiber optic probes can be designed to optimize the collection of Raman-scattered photons from application-dependent depths, and this critical consideration should be addressed when planning a study. Herein we investigate four distinct probe geometries for sensitivity to superficial and deep signals through a Monte Carlo model that incorporates Raman scattering and fluorescence. Experimental validation using biological tissues was performed to accurately recapitulate in vivo scenarios. Testing in biological tissues agreed with modeled results and revealed that microlens designs had slightly enhanced performance at shallow depths (< 1 mm), whereas all of the beampath-modified designs yielded more signal from deep within tissue. Simulation based on fluence maps generated using ray-tracing in the absence of optical scattering had drastically different results as a function of depth for each probe compared to the biological simulation. The contrast in simulation results between the non-scattering and biological tissue phantoms underscores the importance of considering the optical properties of a given application when designing a fiber optic probe. The model presented here can be easily extended for optimization of entirely novel probe designs prior to fabrication, reducing time and cost while improving data quality. 相似文献
143.
Isaac S. Gomes-Filho Julita Maria F. Coelho Samilly S. Miranda Simone S. Cruz Soraya C. Trindade Eneida M.M. Cerqueira Johelle S. Passos-Soares Maria da Conceição N. Costa Maria Isabel P. Vianna Ana Cláudia M.G. Figueiredo Alexandre Marcelo Hintz Amanda F. Coelho Luiz Carlos S. Passos Maurício L. Barreto Frank Scannapieco 《Journal of periodontology》2020,91(11):1444-1452
144.
Paulo Ernando Ferraz Cavalcanti Michel Pompeu Barros de Oliveira Sá Cecília Andrade dos Santos Isaac Melo Esmeraldo Mariana Leal Chaves Ricardo Felipe de Albuquerque Lins Ricardo de Carvalho Lima 《Brazilian Journal Of Cardiovascular Surgery》2015,30(2):148-158
Objective
To determine whether stratification of complexity models in congenital heart surgery (RACHS-1, Aristotle basic score and STS-EACTS mortality score) fit to our center and determine the best method of discriminating hospital mortality.Methods
Surgical procedures in congenital heart diseases in patients under 18 years of age were allocated to the categories proposed by the stratification of complexity methods currently available. The outcome hospital mortality was calculated for each category from the three models. Statistical analysis was performed to verify whether the categories presented different mortalities. The discriminatory ability of the models was determined by calculating the area under the ROC curve and a comparison between the curves of the three models was performed.Results
360 patients were allocated according to the three methods. There was a statistically significant difference between the mortality categories: RACHS-1 (1) - 1.3%, (2) - 11.4%, (3)-27.3%, (4) - 50 %, (P<0.001); Aristotle basic score (1) - 1.1%, (2) - 12.2%, (3) - 34%, (4) - 64.7%, (P<0.001); and STS-EACTS mortality score (1) - 5.5 %, (2) - 13.6%, (3) - 18.7%, (4) - 35.8%, (P<0.001). The three models had similar accuracy by calculating the area under the ROC curve: RACHS-1- 0.738; STS-EACTS-0.739; Aristotle- 0.766.Conclusion
The three models of stratification of complexity currently available in the literature are useful with different mortalities between the proposed categories with similar discriminatory capacity for hospital mortality. 相似文献145.
146.
147.
Salazar-Ciudad I Jernvall J 《Proceedings of the National Academy of Sciences of the United States of America》2002,99(12):8116-8120
Generation of morphological diversity remains a challenge for evolutionary biologists because it is unclear how an ultimately finite number of genes involved in initial pattern formation integrates with morphogenesis. Ideally, models used to search for the simplest developmental principles on how genes produce form should account for both developmental process and evolutionary change. Here we present a model reproducing the morphology of mammalian teeth by integrating experimental data on gene interactions and growth into a morphodynamic mechanism in which developing morphology has a causal role in patterning. The model predicts the course of tooth-shape development in different mammalian species and also reproduces key transitions in evolution. Furthermore, we reproduce the known expression patterns of several genes involved in tooth development and their dynamics over developmental time. Large morphological effects frequently can be achieved by small changes, according to this model, and similar morphologies can be produced by different changes. This finding may be consistent with why predicting the morphological outcomes of molecular experiments is challenging. Nevertheless, models incorporating morphology and gene activity show promise for linking genotypes to phenotypes. 相似文献
148.
Andrew A Adjei Henry B Armah Foster Gbagbo Isaac Boamah Clement Adu-Gyamfi Isaac Asare 《BMC infectious diseases》2008,8(1):111
Background
Human herpesvirus 8 (HHV-8), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are prevalent in Africa, but less common elsewhere and the modes of transmission are still subject to debate. Generally, they rarely cause disease in the immunocompetent host but are highly oncogenic when associated with immunosuppression. Although the high prevalence of HHV-8, CMV and EBV has been well documented in Africa, such data are sparse from Ghana. 相似文献149.
To determine the effects of left ventricular hypertrophy on eplcardlal activation of the human heart, Intraoperative eplcardlal mapping of 40 to 66 points was performed In 10 patients undergoing aortic valve replacement. Mean calculated left ventricular mass was 364 ± 98 g. All patients had normal left ventricular contraction. Earliest eplcardlal activation occurred In the anterior right ventricle In all patients. In 9 patients, it was the only eplcardlal breakthrough point. One patient had a single Inferior left ventricular breakthrough point. Eplcardlal activation spread from the right ventricle towards the left ventricle in both the anterior and inferior direction. Latest eplcardlal activation occurred at the base of the left ventricle In 9 patients and the base of the right ventricle In 1.When compared with patients with coronary artery disease, normal ventricular contraction, and no left ventricular hypertrophy, patients with hypertrophy had fewer left ventricular breakthrough points (p <0.001) and were more likely to have latest activation at the left ventricular base (p <0.001).We conclude that left ventricular hypertrophy Is associated with marked changes In the pattern of epicardlal activation. These changes may reflect delay In spread from endocardium due to the increased wall thickness. 相似文献
150.
Polymyalgia rheumatica 总被引:3,自引:0,他引:3
Polymyalgia rheumatica is a syndrome that occurs in the elderly and is characterized by pain and stiffness involving the neck, the shoulder girdle, and the hip girdle. The aching should be present for greater than one month. Polymyalgia rheumatica may be more common than reported. The etiology remains unknown. There is generally little found pathologically in this disease. The physical examination is often not impressive. Synovitis may be a main contributing factor to many of the symptoms seen in patients with polymyalgia rheumatica. Symptoms often do not correlate with physical findings. Polymyalgia rheumatica must be differentiated from many conditions since the diagnosis remains entirely clinical. Osteoarthritis, flu syndromes, inflammatory myopathies, fibromyalgia, and depression all have features that may mimic polymyalgia rheumatica. Malignancies and infections may also be difficult to separate from polymyalgia rheumatica. Polymyalgia rheumatica may also be extremely difficult to differentiate from seronegative rheumatoid arthritis in patients older than 50 years. Although some patients with polymyalgia rheumatica have underlying giant cell arteritis, the majority apparently do not. The distinction between polymyalgia rheumatica and giant cell arteritis cannot be made on the basis of laboratory studies and relies solely on clinical symptoms and physical findings. Although nonsteroidal antiinflammatory medications may control symptoms in patients with mild disease, most patients with polymyalgia rheumatica require low-dose corticosteroids. The tapering schedule for the corticosteroids is contingent upon the response of symptoms and laboratory parameters. Polymyalgia rheumatica usually follows a benign course with almost complete response to an adequate treatment program. Recently, there have been several studies suggesting that the course of polymyalgia rheumatica may not be as short and simple as once proposed. Nevertheless, many patients may be completely weaned from corticosteroids. Other agents have been used in this disease, but for the most part their use remains somewhat controversial. Patients must be monitored carefully. Most patients do well, and treatment is effective. 相似文献