全文获取类型
收费全文 | 14565篇 |
免费 | 903篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 192篇 |
儿科学 | 526篇 |
妇产科学 | 244篇 |
基础医学 | 1690篇 |
口腔科学 | 516篇 |
临床医学 | 1076篇 |
内科学 | 4085篇 |
皮肤病学 | 469篇 |
神经病学 | 939篇 |
特种医学 | 336篇 |
外国民族医学 | 1篇 |
外科学 | 2197篇 |
综合类 | 54篇 |
一般理论 | 14篇 |
预防医学 | 1223篇 |
眼科学 | 262篇 |
药学 | 745篇 |
中国医学 | 48篇 |
肿瘤学 | 899篇 |
出版年
2023年 | 72篇 |
2022年 | 186篇 |
2021年 | 418篇 |
2020年 | 193篇 |
2019年 | 390篇 |
2018年 | 538篇 |
2017年 | 318篇 |
2016年 | 325篇 |
2015年 | 359篇 |
2014年 | 537篇 |
2013年 | 628篇 |
2012年 | 982篇 |
2011年 | 1026篇 |
2010年 | 574篇 |
2009年 | 542篇 |
2008年 | 838篇 |
2007年 | 899篇 |
2006年 | 800篇 |
2005年 | 848篇 |
2004年 | 697篇 |
2003年 | 703篇 |
2002年 | 674篇 |
2001年 | 364篇 |
2000年 | 424篇 |
1999年 | 333篇 |
1998年 | 122篇 |
1997年 | 100篇 |
1996年 | 101篇 |
1995年 | 76篇 |
1994年 | 70篇 |
1993年 | 45篇 |
1992年 | 175篇 |
1991年 | 160篇 |
1990年 | 111篇 |
1989年 | 113篇 |
1988年 | 97篇 |
1987年 | 96篇 |
1986年 | 81篇 |
1985年 | 78篇 |
1984年 | 50篇 |
1983年 | 37篇 |
1981年 | 36篇 |
1980年 | 22篇 |
1979年 | 30篇 |
1978年 | 18篇 |
1977年 | 25篇 |
1976年 | 22篇 |
1973年 | 20篇 |
1972年 | 17篇 |
1971年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Deoxynivalenol (DON) remains one of the most concerning mycotoxins produced by the Fusarium genus due to the wide occurrence in highly consumed cereal-based food and its associated toxicological effects. Previous studies conducted in Spain and other European countries suggested that some vulnerable groups such as children could be exceeding the tolerable daily intakes. Thus, the aim of this study was to conduct a comprehensive and updated dietary exposure assessment study in Spain, with a specific analysis in the region of Catalonia. Cereal-based food samples collected during 2019 were analysed using liquid chromatography coupled to tandem mass spectrometry for multi-mycotoxin detection including DON and its main metabolites and derivatives. Consumption data were gathered from the nation-wide food surveys ENALIA and ENALIA2 conducted in Spain, and a specific survey conducted in Catalonia. The data were combined using deterministic and semi-parametric probabilistic methods. The results showed that DON was widely present in cereal-based food highly consumed in Spain and the Catalonia region. Exposure to DON among the adult population was globally low; however, among infants aged 3–9 years, it resulted in the median of 192 ng/kg body weight/day and the 95th percentiles of 604 ng/kg body weight/day, that would exceed the most conservative safety threshold for infants. Bread and pasta were the main contributing foodstuffs to the global exposure to DON, even among infants; thus, those foods should be considered a priority for food control or to develop strategies to reduce the exposure. In any case, further toxicological and epidemiological studies are required in order to refine the safety thresholds accounting for the sensitivity of the infant population. 相似文献
103.
Arachidonic acid (AA) metabolites control cell proliferation, among other physiologic functions. RAW 264.7 macrophages can metabolise AA through the cyclooxygenase and lipoxygenase (LOX) pathways. We aimed to study the role of AA-metabolites derived from 5-LOX in the control of RAW 264.7 macrophage growth. Our results show that zileuton, a specific 5-LOX inhibitor, and nordihydroguaiaretic acid (NDGA), a non-specific LOX inhibitor, inhibit cell proliferation and [(3)H]-thymidine incorporation in a concentration-dependent fashion. Growth inhibition induced by NDGA can be explained by an apoptotic process, while zileuton does not seem to induce apoptosis. Moreover, these treatments delay the cell cycle, as analysed by flow cytometry. On the other hand, the leukotriene (LT) B(4) receptor antagonist U-75302, the LTD(4) receptor antagonists LY-171883 and MK-571, and the cysteinyl-LT receptor antagonist REV-5901 also inhibit cell proliferation and [(3)H]-thymidine incorporation in a concentration-dependent manner, and delay the RAW 264.7 cell cycle. However, these antagonists did not induce annexin V staining, caspase activation or DNA fragmentation. Furthermore, we demonstrated that exogenous addition of LTB(4) or LTD(4) revert the cell growth inhibition induced by zileuton or the leukotriene receptor antagonists mentioned above. Finally, we observed that LTB(4) and LTD(4), in the absence of growth factors, have pro-proliferative effects on macrophages, and we obtained preliminary evidences that this effect could be through mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways. In conclusion, our results show that the interaction between LTB(4) and LTD(4) with its respective receptor is involved in the control of RAW 264.7 macrophage growth. 相似文献
104.
105.
106.
107.
Medina Castro N Moreno Alvarez O Guzmán Huerta M Hernández Andrade E 《Ginecología y obstetricia de México》2007,75(10):621-629
Introduction of Doppler ultrasound in obstetrical practice has changed both management and understanding of several diseases that put at risk women and them fetuses. To establish necessary basics and correctly apply this technique, this review will focus in physical principles, acquisition methods, consistency, and safety issues of Doppler ultrasound, in order to improve precision, accuracy and interpretation of this methodology. 相似文献
108.
Moro M Figueras-Aloy J Fernández C Doménech E Jiménez R Pérez-Rodríguez J Pérez-Sheriff V Quero J Roqués V;Grupo SEN 《American journal of perinatology》2007,24(10):593-601
The purpose of this study was to analyze the mortality and its prognostic factors in a Spanish cohort of very low birthweight (VLBW) infants during the period 2002 to 2005. Using the Spanish Society of Neonatology database (SEN 1500), 8942 infants with a birthweight < 1500 g were recruited. The overall mortality was 17.3%. However, this incidence underwent a significant decrease over the study period, from 19.4% in 2002 to 15.2% in 2005 ( P = 0.003). Mortality ranged from 12.4% in 25% of the participating neonatal units to 19.4% in a further 25%. Mortality was higher in outborn infants (25.8%) than in inborn infants (16.6%) ( P < 0.001). The mortality rates of these neonates are also presented by 100-g intervals (401 to 1500) and for the different hospitalization times: in the delivery room, within 24 hours and 28 days of birth, at 36 weeks of postmenstrual age, and on discharge. Of note was that mortality was greatest within 24 hours and 28 days of birth in each of the weight groups ( P < 0.001). In conclusion, in the cohort of infants < 1500 g examined, mortality in the period from 2002 to 2005 was still high, especially among newborns weighing < 1000 g. We did, however, observe a decreasing trend in mortality rates for the participating neonatal units over the 4 study years. Our findings highlight the need to promote intrauterine transport and improve neonatal transport as well as the management of these infants in the delivery room and within the first 28 days of life. 相似文献
109.
Injected intracranially in the dba strain of mice, murine typhus rickettsiae caused a serially transmissible meningoencephalitis similar to that produced by psittacosis and certain other viruses. All injected mice of this strain suddenly became ill and approximately half of these animals died on the 5th and 6th days after injection. Swiss mice injected in parallel series showed illness in only a few animals, and no deaths occurred. These experiments were carried out at room temperatures ranging from 60–80°F. After intraperitoneal injection, a uniformly fatal rickettsial peritonitis developed in all dba mice kept at environmental temperatures of 65–73°F. or 70–80°F. Death occurred between the 3rd and 7th days after injection, depending somewhat on the dosage used. Among Swiss, brown agouti, and A albino mice injected in parallel series, the mortality was less than 60 per cent. These experiments indicate that mice of the dba strain are much more susceptible to murine typhus than are mice of the other three strains studied. 相似文献
110.
Gloria PrezGimeno Azahara I. Ruperez Mercedes GilCampos Concepcin M. Aguilera Augusto Anguita Rocío VzquezCobela Estela Skapino Luis A. Moreno Rosaura Leis Gloria BuenoLozano 《Journal of clinical hypertension (Greenwich, Conn.)》2022,24(6):713
Due to the absence of easily applicable cut‐off points to determine high blood pressure or hypertension in children, as in the adult population, blood pressure is rarely measured in the pediatrician''s clinical routine. This has led to an underdiagnosis of high blood pressure or hypertension in children. For this reason, the present study evaluate the utility of five equations for the screening of high blood pressure in children: blood pressure to height ratio, modified blood pressure to height ratio, new modified blood pressure to height ratio, new simple formula and height‐based equations. The authors evaluated 1599 children between 5 and 18 years. The performance of the five equations was analyzed using the receiver‐operating characteristics curves for identifying blood pressure above P90th according to the American Academy of Pediatrics Clinical Practice Guideline 2017. All equations showed an area under the curve above 0.882. The new modified blood pressure to height ratio revealed a high sensitivity whereas the height‐based equations showed the best performance, with a positive predictive value above 88.2%. Finally, all equations showed higher positive predictive values in children with overweight or obesity. The height‐based equation obtained the highest PPV values above 71.1% in children with normal weight and above 90.2% in children with overweight or obesity. In conclusions, the authors recommend the use of the height‐based equations equation because it showed the best positive predictive values to identify children with elevated blood pressure, independently of their sex, pubertal and weight status. 相似文献