全文获取类型
收费全文 | 10798篇 |
免费 | 681篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 249篇 |
妇产科学 | 261篇 |
基础医学 | 1529篇 |
口腔科学 | 272篇 |
临床医学 | 992篇 |
内科学 | 2696篇 |
皮肤病学 | 258篇 |
神经病学 | 1160篇 |
特种医学 | 260篇 |
外科学 | 1231篇 |
综合类 | 40篇 |
一般理论 | 4篇 |
预防医学 | 774篇 |
眼科学 | 190篇 |
药学 | 700篇 |
中国医学 | 34篇 |
肿瘤学 | 796篇 |
出版年
2024年 | 12篇 |
2023年 | 98篇 |
2022年 | 182篇 |
2021年 | 297篇 |
2020年 | 182篇 |
2019年 | 271篇 |
2018年 | 316篇 |
2017年 | 262篇 |
2016年 | 292篇 |
2015年 | 317篇 |
2014年 | 404篇 |
2013年 | 537篇 |
2012年 | 829篇 |
2011年 | 863篇 |
2010年 | 455篇 |
2009年 | 423篇 |
2008年 | 700篇 |
2007年 | 725篇 |
2006年 | 652篇 |
2005年 | 706篇 |
2004年 | 623篇 |
2003年 | 579篇 |
2002年 | 525篇 |
2001年 | 99篇 |
2000年 | 86篇 |
1999年 | 109篇 |
1998年 | 74篇 |
1997年 | 74篇 |
1996年 | 64篇 |
1995年 | 61篇 |
1994年 | 56篇 |
1993年 | 43篇 |
1992年 | 60篇 |
1991年 | 60篇 |
1990年 | 52篇 |
1989年 | 27篇 |
1988年 | 33篇 |
1987年 | 37篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 41篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1975年 | 13篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Mari S. Stavanja Paul H. Ayres Daniel R. Meckley Elizabeth R. Bombick Michael F. Borgerding Michael J. Morton Charles D. Garner Deborah H. Pence James E. Swauger 《Experimental and toxicologic pathology》2006,57(4):267-281
A tiered testing strategy has been developed to evaluate the potential for new ingredients, tobacco processes, and technological developments to alter the biological activity that results from burning tobacco. A series of studies was initially conducted with cigarettes containing 3% high fructose corn syrup (HFCS) as an alternate tobacco casing material to corn syrup/invert sugar, including determination of selected mainstream cigarette smoke (MS) constituent yields, Ames assay, sister chromatid exchange (SCE) assay in Chinese hamster ovary (CHO) cells, a 30-week dermal tumor-promotion evaluation of cigarette smoke condensate (CSC) in SENCAR mice, and a 13-week subchronic inhalation study of MS in Sprague-Dawley rats. A second series of studies was conducted with cigarettes containing 3%, 4% and 5% HFCS including MS chemistry, Ames assay, SCE assay in CHO cells, and a neutral red cytotoxicity assays. Collectively, mainstream smoke chemistry, genotoxicity, dermal tumor-promotion, and inhalation toxicity studies demonstrated no differences between cigarettes with 3% HFCS and cigarettes with 3% corn syrup/invert sugar. Also, mainstream smoke chemistry and genotoxicity of cigarettes with 4% and 5% HFCS were not different from cigarettes with 3% HFCS. In conclusion, the addition of up to 5% HFCS to cigarette does not alter the mainstream smoke chemistry or biological activity of mainstream smoke or mainstream smoke condensate as compared to cigarettes with 3% corn syrup/invert sugar with regard to the parameters investigated and presented. 相似文献
33.
34.
β-N-Acetylhexosaminadases in human cerebrospinal fluid and serum of patients with multiple sclerosis
Alessandro Datti Carla Emiliani Giuseppe Capocchi Aldo Orlacchio 《Clinica chimica acta; international journal of clinical chemistry》1991,200(2-3)
β-N-Acetylhexosaminidase activity and isoenzyme have been investigated in normal human cerebrospinal fluid and that of patients with multiple sclerosis. β-N-acetylhexosaminidase activity in normal cerebrospinal fluids has been resolved into five components. The major component was in a form that eluted from DEAE cellulose at the same salt concentration as hexosaminidase As, the isoenzyme previously identified in human serum. Cerebrospinal fluid from patients exhibited a different isoenzyme profile, showing a remarkable increase in a form having a pI which was more acidic than that of As. These changes have a potential use in the diagnosis and further biochemical characterization of multiple sclerosis. 相似文献
35.
A validity study of the Brazilian version of the 15-item Short Psychiatric Evaluation Schedule (SPES), included in the mental health assessment of Older Americans Resources and Services (OARS), designed to detect psychiatric disorders in the elderly, against the "caseness" criterion suggested by Cooper and Schwarz was carried out with a community sample, as part of a survey to study health and living conditions of the elderly in a large urban center of a developing country, S?o Paulo, Brazil. The screening questionnaire was completed by 292 subjects, and 91 were selected for the psychiatric interview. The validity coefficients were as follows: sensitivity 61%, specificity 89%, positive predictive value 66%, negative predictive value 87% and misclassification rate 18%. A discriminant analysis using a stepwise procedure was then applied to select the best item discriminators of the screening questionnaire. The best set of discrimination comprised six items leading to the following validity coefficients: sensitivity 82%, specificity 77%, positive predictive value 58%, negative predictive value 92% and misclassification rate 21%. The possible factors related to false positive and false negative responses on the screening are discussed. 相似文献
36.
Salvatore Metafora Gianfranco Peluso Gianpietro Ravagnan Magda Marchese Michele di Pietro Aldo Mancini Nicola Panza Antonio Fusco Raffaele Porta 《Medical oncology (Northwood, London, England)》1988,5(4):223-231
Transglutaminase (TGase) activity was reduced in intact mitogen-stimulated human peripheral blood lymphocytes (PBL) when compared to intact resting PBL. Moreover, a treatment of the same quiescent immunocompetent cells with purified liver TGase and Ca2+ completely suppressed the mitogen-induced blast transformation. A decrease in TGase activity in neoplastically transformed seminal vesicle epithelial cells with respect to their normal parent counterpart was also observed. Our data support the notion of a possible implication of TGase in cell proliferation and transformation. 相似文献
37.
A reduced version of the Face-Hand Test (FHT), the FHT-R, was applied to a random sample of 91 elderly subjects living in the community (S. Paulo-Brazil), to study the instrument's ability to detect Organic Brain Syndrome (OBS). The scores of the FHT-R test were then compared with a psychiatric assessment using the Clinical Interview Schedule. Five persons were regarded as OBS "cases" and 86 as OBS "non cases". At the cut-off point 0/1 the validity coefficients were as follows: Sensitivity 60%, Specificity 94%, Positive Predictive Value 38%, Negative Predictive Value 98% and Overall Misclassification Rate 8%. The usefulness of this clinical test to screen for OBS in epidemiological surveys is discussed. 相似文献
38.
Takaaki Ohmori Ryo Tabei Norimasa Arita Mari Kondo Tetsuo Kozawa Yoshinori Chikamori Norifumi Ueda 《Pathology international》1983,33(5):999-1007
This report concerns a case of solitary extramedullary plasmacytoma of the left submandibular lymph node in a 56-year-old man. The tumor showed monoclonal proliferation of abnormal plasma cells which revealed highly positive stainings of both methylgreen pyronin and kappa light chain using the immunoperoxidase technique in the cytoplasms, and further revealed massive'.amyloid'deposits in the stroma, which suggested the possibility of sequential amyloid formation upon the secretion of paraprotein by tumor cells. 相似文献
39.
Lindström M Nevas M Kurki J Sauna-aho R Latvala-Kiesilä A Pölönen I Korkeala H 《Journal of clinical microbiology》2004,42(10):4718-4725
The largest reported outbreak of type C botulism in fur production animals is described. Epidemiological investigation of 117 out of 157 (response rate, 74.5%) farms revealed that 44,130 animals died or were euthanized, while 8,033 animals with milder symptoms recovered. The overall death rate in all animals at risk was 21.7%. The death rates were significantly higher in blue and shadow foxes (24.2 and 27.8%, respectively) than in silver and blue silver foxes and minks (below 4%). All minks had been immunized against botulinum toxin type C. Deaths were associated with feed manufactured by a local processor, 83 of whose customer farms (70.9%) reported dead or sick animals. Five feedlots out of 19 delivered to the farms on the day preceding the onset of the outbreak (day 2) were associated with a death rate higher than 40%. These feedlots consisted of fresh feed processed on day 2 and feed processed 1 day earlier (day 1). In laboratory analysis, the day 2 feed contained botulinum toxin type C (>600 minimum lethal doses/g), while the day 1 feed did not contain toxin. Toxin was not detected in feed raw-material samples. Clostridium botulinum type C was detected by PCR in some feed components and in feed. However, as the feed temperature was continuously 8 degrees C or below and the pH was continuously 5.6 or below according to the manufacturer, it seems unlikely that spore germination and toxin formation occurred during overnight storage. Hence, the events leading to toxin formation were not determined. 相似文献
40.