全文获取类型
收费全文 | 9153篇 |
免费 | 526篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 151篇 |
儿科学 | 244篇 |
妇产科学 | 131篇 |
基础医学 | 1374篇 |
口腔科学 | 865篇 |
临床医学 | 632篇 |
内科学 | 2162篇 |
皮肤病学 | 152篇 |
神经病学 | 683篇 |
特种医学 | 191篇 |
外国民族医学 | 2篇 |
外科学 | 812篇 |
综合类 | 42篇 |
一般理论 | 4篇 |
预防医学 | 946篇 |
眼科学 | 128篇 |
药学 | 656篇 |
中国医学 | 58篇 |
肿瘤学 | 472篇 |
出版年
2023年 | 80篇 |
2022年 | 207篇 |
2021年 | 300篇 |
2020年 | 191篇 |
2019年 | 258篇 |
2018年 | 309篇 |
2017年 | 209篇 |
2016年 | 263篇 |
2015年 | 295篇 |
2014年 | 377篇 |
2013年 | 479篇 |
2012年 | 739篇 |
2011年 | 782篇 |
2010年 | 425篇 |
2009年 | 347篇 |
2008年 | 557篇 |
2007年 | 598篇 |
2006年 | 511篇 |
2005年 | 428篇 |
2004年 | 391篇 |
2003年 | 340篇 |
2002年 | 309篇 |
2001年 | 143篇 |
2000年 | 154篇 |
1999年 | 140篇 |
1998年 | 66篇 |
1997年 | 59篇 |
1996年 | 39篇 |
1995年 | 25篇 |
1994年 | 26篇 |
1993年 | 19篇 |
1992年 | 65篇 |
1991年 | 59篇 |
1990年 | 51篇 |
1989年 | 50篇 |
1988年 | 46篇 |
1987年 | 33篇 |
1986年 | 34篇 |
1985年 | 45篇 |
1984年 | 33篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 18篇 |
1968年 | 12篇 |
排序方式: 共有9705条查询结果,搜索用时 15 毫秒
1.
Afterpotential characteristics and firing patterns in maturing rat hippocampal CA1 neurones in in vitro slices. 总被引:2,自引:0,他引:2
The postnatal evolution of depolarizing after-potentials (DAPs) and after-hyperpolarizations (AHPs) was studied in rat CA1 hippocampal neurones (5-68 days of age) using in vitro slices. Results were pooled into 4 age groups: P5-9, P10-16, P17-24 and P26-68. In P5-9 cells, DAPs were seen as passive signals, with a time constant similar to the time constant of the membrane. The evolution of the DAP was characterized by a decrease in amplitude, an increase in duration and a change in contour. In P10-16 and P17-24 cells, the DAPs often had a plateau or a hump-like shape which increased the probability of firing and the occurrence of spike doublets. The firing pattern and bursting behaviour of P10-16 CA1 neurones differed from the pattern typical of the adult. P5-9 and P10-16 cells had post-burst AHPs with a smaller amplitude and a more prolonged early phase than at late stages of development. 相似文献
2.
ngela P. de Mattos Tereza C.M. Ribeiro Patrícia S.A. Mendes Sandra S. Valois Carlos M.C. Mendes Hugo C. Ribeiro Jr 《Nutrition Research》2009,29(7):462-469
Although previous studies have shown successful treatment of persistent diarrhea (PD) with the use of yogurt-based diets, some recent ones speculate the need of special formulas for the nutritional management of PD complicated cases. In the present study, we tested the hypothesis that the consumption of 3 lactose-free diets, with different degrees of complexity, is associated with lower stool output and shorter duration of diarrhea when compared with the use of a yogurt-based one on the nutritional management of PD. A total of 154 male infants, aged between 1 and 30 months, with PD and with or without dehydration, were randomly assigned to 1 of 4 treatment groups. Throughout the study, the patients were placed in a metabolic unit; their body weights and intakes of oral rehydration solution, water, and formula diets, in addition to outputs of stool, urine, and vomit, were measured and recorded at 24-hour intervals. Four different diets were used in this study: diet 1, yogurt-based formula; diet 2, soy-based formula; diet 3, hydrolyzed protein-based formula; and diet 4, amino acid–based formula. Throughout the study, only these formula diets were fed to the children. The data showed that children fed the yogurt-based diet (diet 1) or the amino acid–based diet (diet 4) had a significant reduction in stool output and in the duration of diarrhea. The use of an inexpensive and worldwide-available yogurt-based diet is recommended as the first choice for the nutritional management of mild to moderate PD. For the few complicated PD cases, when available, a more complex amino acid–based diet should be reserved for the nutritional management of these unresponsive and severe presentations. Soy-based or casein-based diets do not offer any specific advantage or benefits and do not seem to have a place in the management of PD. 相似文献
3.
Milena Soares Santos Guilherme de Sousa Ribeiro Tainara Queiroz Oliveira Renan Cardoso Nery Santos Edilane Gouveia Kátia Salgado Daniele Takahashi Cleuber Fontes Leila Carvalho Campos Mitermayer Galvão Reis Albert Icksang Ko Joice Neves Reis 《International journal of infectious diseases》2009,13(4):456-461
4.
5.
A case of Bonnet syndrome associated with blindness due to bilateral eye disease and a posterior parasagittal meningioma is reported. It is assumed that visual afferent deprivation alone is not enough to produce the syndrome and that, in most instances, a 'cerebral factor' must be operative if hallucinoses are to occur. The distinction between hallucinosis and hallucinations is favored and a common neural circuit for the mediation of hallucinotic imageries in general is suggested. One should not immediately put the blame on obvious eye or visual pathways affections when facing cases of Bonnet syndrome, as they are not likely to explain the complex array of images perceived by any given patient. On the contrary, the possibility of a clinically covert intracranial disease should be always raised and intensively looked for. 相似文献
6.
Marcos Ribeiro Luciene Angelini Priscila Games Robles-Ribeiro Rafael Stelmach Ubiratan de Paula Santos Mario Terra-Filho 《The Journal of asthma》2007,44(5):371-375
Background. The European Community Respiratory Health Survey (ECRHS) questionnaire was planned to answer questions about the distribution of asthma. Our objective was to determine the cultural equivalence of the ECRHS into the Brazilian-Portuguese language. Methods. We translated the ECRHS according to international criteria. Results. Small cultural adaptations were necessary. Among the 80 participating patients, the Cronbach indices were higher (0.98-1.00) and the Kappa indices varied from 0.77 to 1.00. Conclusion. The study suggests that the Brazilian version of the ECRHS is conceptually equivalent to the original and similarly reliable and may be used in international studies involving Portuguese-speaking respiratory patients. 相似文献
7.
Background
Due to marginalization, trafficking violence, conflicts with the police and organic and social psychological problems associated with the drug, crack is one of the most devastating drugs currently in use. However, there is evidence that some users manage to stay alive and active while using crack cocaine for many years, despite the numerous adversities and risks involved with this behavior. In this context, the aim of the present study was to identify the strategies and tactics developed by crack users to deal with the risks associated with the culture of use by examining the survival strategies employed by long-term users. 相似文献8.
9.
Sandra Guerra A Teixeira Pinto José Ribeiro José Oliveira José Duarte Jorge Mota 《Revista portuguesa de cardiologia》2003,22(2):167-182
An important aspect of preventive medicine is to identify subjects at risk as soon as possible, so preventive strategies can be introduced at early ages. The justification for this strategy is twofold: firstly, the assumption that children maintain a particular high value of a risk factor for disease throughout life; and secondly, the assumption that lowering the level of the risk factor in early life will have a greater impact on the disease than will risk factor changes in later life. In epidemiology the analysis of such factors over time is referred to as tracking. Tracking analysis has been applied to risk factors for cardiovascular diseases (CVD) in pediatric years. The aims of this study were: I) to analyze the stability of biological risk factors [high blood pressure (BP), high percentage of fat mass (%FM) and high total cholesterol (TC)] and lifestyle risk factors [low physical activity index (PAI)] in isolation; and II) to analyze the stability of zero, one, two or three biological risk factors. There were two evaluations in 692 children and adolescents (325 boys and 367 girls), aged between 8 and 15 years. The quartiles, adjusted for age and gender, were the criterion used to identify subjects with biological risk factors (fourth quartile) and with lifestyle risk factors (first quartile) for CVD. The stability was calculated through the relative frequency of subjects who maintained or changed quartile between the two evaluations. There is stability for biological risk factors as well as for behavioral and/or lifestyle risk factors. However, the highest stability is seen in biological risk factors. 相似文献
10.
The effects of HgCl2 on the epidermis of Trichomycterus brasiliensis were studied by histological, histochemical, and ultrastructural methods. First, the normal organization of the tissue was described in order to study the HgCl2 effects on the skin structure. The epithelial cells presented a typical structural organization found in many fishes. Basically five types of cells could be detailed: goblet cells, club cells, germinative stratum cells, intermediate layer cells, and epithelial cells in the superficial layer. The goblet cells in the superficial layer present evidence of secretory activity by positive histochemical reactions. In cells exposed to HgCl2, different morphological alterations were observed in the epithelium structure, such as an increase in the lymphocyte number, hypertrophied epithelial cells at the surface, modified taste buds, obstruction of the goblet cells pore, and high cellular proliferation. Moreover, the chemical nature of the goblet cells was not modified by the presence of the HgCl2 dissolved in water. All animals died within 24 hr after the contamination with inorganic mercury at concentrations of 0.2 and 0.1 mg HgCl2/liter. 相似文献