全文获取类型
收费全文 | 2469篇 |
免费 | 148篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 72篇 |
儿科学 | 46篇 |
妇产科学 | 31篇 |
基础医学 | 379篇 |
口腔科学 | 198篇 |
临床医学 | 157篇 |
内科学 | 563篇 |
皮肤病学 | 32篇 |
神经病学 | 259篇 |
特种医学 | 45篇 |
外科学 | 197篇 |
综合类 | 12篇 |
预防医学 | 173篇 |
眼科学 | 43篇 |
药学 | 249篇 |
中国医学 | 21篇 |
肿瘤学 | 150篇 |
出版年
2023年 | 18篇 |
2022年 | 53篇 |
2021年 | 91篇 |
2020年 | 54篇 |
2019年 | 73篇 |
2018年 | 99篇 |
2017年 | 53篇 |
2016年 | 71篇 |
2015年 | 76篇 |
2014年 | 140篇 |
2013年 | 169篇 |
2012年 | 218篇 |
2011年 | 242篇 |
2010年 | 99篇 |
2009年 | 94篇 |
2008年 | 157篇 |
2007年 | 137篇 |
2006年 | 135篇 |
2005年 | 109篇 |
2004年 | 103篇 |
2003年 | 87篇 |
2002年 | 78篇 |
2001年 | 23篇 |
2000年 | 34篇 |
1999年 | 19篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 8篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 17篇 |
排序方式: 共有2627条查询结果,搜索用时 656 毫秒
1.
A Montanara R Pani R Pellegrini N S Polli S Soluri 《The British journal of radiology》1986,59(708):1171-1173
This paper describes research into measurement and reduction of the radiation dose to the lens during various examinations, namely skull and orbit, optic canal and optic strut, superior and inferior orbital fissure, localisation of foreign bodies in the eye, calcifications, orbital fractures, macrodacryography and orbital venography. Using rare-earth screens and high-sensitivity films, without an antiscattering grid, and with an added filtration of 0.5 mm Cu, it is possible to reduce the radiological risk during all investigations involving skull, orbit and eyeballs, while maintaining a good image quality. Particularly in those examinations with direct magnification (macrodacryography and venography, foreign bodies in the eye, orbital fractures), the dose to the lens is very low: less than 0.2 mGy/radiograph. 相似文献
2.
Laipcarpine (LC), a pyorrolizidine alkaloid, is able to inducea series of chronic and progressive lesions in rat liver, includingalong-lasting block in the cell cycle, the appearance of enlargedhepatocytes (megalocytosis), fibrosis, cirrhosis and malignantneoplasms. In this study the effect of transplantation of normalhepatocytes on the development of LC (80 µmol/kg i.p.).Four weeks later all animals were subjected to 2/3 paroticlhepatectomy (PH). In addition, at the time of PH one group ofrats were transplanted with normal hepatocytes isolated froma syngeneic donor (106 cells/rat via the portal vein), whilethe other group received only the culture medium. All rats werekilled 14 weeks after the operation. Grossly, the liver of ratsexposed to LC followed by PH with no transplantation of normalhepatocytes was small in size (% liver wt/body wt 1.66 ±0.08) and exhibited a few whitish nodules. Histologically, 相似文献
3.
P K Das A Manoharan S Subramanian K D Ramaiah S P Pani A R Rajavel P K Rajagopalan 《Epidemiology and infection》1992,108(3):483-493
An Integrated Vector Management (IVM) strategy was implemented from 1981 to 1985 in one part of Pondicherry, South India, for the control of the bancroftian filariasis vector Culex quinquefasciatus (the IVM area). The rest of the town (the comparison area) received the conventional larvicidal input. After 1985 both the areas were managed conventionally. The switch to conventional strategy resulted in an increase of vector density in both areas. The microfilaraemia prevalence in humans showed a general decline (P less than 0.05) from 1986 to 1989 only in the IVM area whereas its intensity did not change significantly in either area. While the age-specific rate of gain of infection was generally unchanged in the IVM area, an increase in all age classes was observed after 1985 in the comparison area, where the Annual Transmission Index was high during the previous years. In both areas the rate of loss of infection increased during 1986-9 compared to 1981-6. The results suggest that 3 years is too short a period to relate the changes in entomological parameters to those in the microfilaraemia status of the population. 相似文献
4.
Di Biase AM Pietrantoni A Tinari A Siciliano R Valenti P Antonini G Seganti L Superti F 《Journal of medical virology》2003,69(4):495-502
Lactoferrin, a member of the transferrin family of approximately 80 kDa, consists of a single polypeptide chain folded in two symmetric, globular lobes (N- and C-lobes), each able to bind one ferric ion. This glycoprotein, found in physiological fluids of mammals, plays an important role in immune regulation and in defense mechanisms against bacteria, fungi, parasites, and viruses. Although the antiviral activity of lactoferrin is one of the major biological functions of such protein, the mechanism of action is still under debate. We have investigated both the role of tryptic fragments of bovine lactoferrin and the mechanism of lactoferrin antiviral effect toward adenovirus infection in HEp-2 cells. The results obtained demonstrated that the anti-adenovirus activity of lactoferrin is mediated by the N-terminal half of the protein as the N-lobe was able to inhibit adenovirus infection, even if at lower extent than undigested lactoferrin, whereas C-lobe was ineffective. The results also showed that the anti-adenovirus action of lactoferrin and of its N-terminal peptide lactoferricin took place on virus attachment to cell membrane, mainly through competition for common glycosaminoglycan receptors. The data provide evidence that the anti-adenovirus activity of lactoferrin is mediated mainly by the cluster of positive charges at the N-terminus of whole molecule and that the N-terminal peptide lactoferricin alone is sufficient to prevent infection. 相似文献
5.
6.
de Andrade AL Pimenta FC Laval CA de Andrade JG Guerra ML Brandileone MC 《Journal of clinical microbiology》2004,42(5):2345-2346
We present a case of invasive pneumococcal infection in a healthy 10-month-old infant from whom Streptococcus pneumoniae serotype 23F was isolated from the blood and serotype 23B was isolated from the cerebrospinal fluid. Both serotypes were penicillin nonsusceptible. Pulsed-field gel electrophoresis analysis demonstrated that the two serotypes had distinct DNA patterns, indicating that infection did not occur as a result of capsular transformation but as a result of a mixed infection with two distinct pneumococcal serotypes. 相似文献
7.
Uniparental disomy 7 in Silver--Russell syndrome and primordial growth retardation 总被引:12,自引:2,他引:12
Kotzot Dieter; Schmitt Silke; Bernasconi Fabiana; Robinson Wendy P.; Lurie Iosif W.; Ilyina Helena; Mehes Karoly; Hamel Ben C.J.; Otten Barto J.; Hergersberg Martin; Werder Edmond; Schoenle Eugen; Schinzel Albert 《Human molecular genetics》1995,4(4):583-587
Maternal uniparental disomy for the entire chromosome 7 hasso far been reported in three patients with intrauterine andpostnatal growth retardation. Two were detected because theywere homozygous for a cystic fibrosis mutation for which onlythe mother was heterozygous, and one because he was homozygousfor a rare COL1A2 mutation. We investigated 35 patients witheither the Silver-Russell syndrome or primordial growth retardationand their parents with PCR markers to search for uniparentaldisomy 7. Four of 35 patients were found to have maternal disomy,including three with isodisomy and one with heterodisomy. Thedata confirm the hypothetical localization of a maternally imprintedgene (or more than one such gene) on chromosome 7. It is suggestedto search for UPD 7 in families with an offspring with sporadicSilver-Russell syndrome or primordial growth retardation. 相似文献
8.
Genetic relationship between Streptococcus pneumoniae isolates from nasopharyngeal and cerebrospinal fluid of two infants with Pneumococcal Meningitis
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
de Andrade AL Pimenta FC Brandileone MC Laval CA Guerra ML de Andrade JG Di Fabio JL 《Journal of clinical microbiology》2003,41(8):3970-3972
The molecular epidemiology of Streptococcus pneumoniae isolates from carriage and cerebrospinal fluid (CSF) concurrently recovered from the same individual has not yet been reported. By using pulsed-field gel electrophoresis, we demonstrated the genetic linkage among strains from CSF and nasopharynges of two children with pneumococcal meningitis. 相似文献
9.
INTRODUCTION: Human Papillomavirus (HPV) infection is considered an important risk factor for the development of cervical carcinoma. The aim of this work was to detect and genotype HPV DNA in cervical lesions from our Province. METHODS: HPV DNA was amplified by polymerase chain reaction (PCR) and genotyped by restriction fragment length polymorphism (RFLP) analysis. A total of 101 biopsies (43 koilocytic atypias, 20 CIN1, 19 CIN2, 17 CIN3 and 2 squamous carcinomas) were analyzed. RESULTS: HPV DNA was found in 41.8% of koilocytic atypias, in 95.0% of CIN1 and 100% of CIN2 and higher grade lesions. Only high risk genotypes were found in CIN2-3 and invasive carcinomas. HPV 16 was the most prevalent type in both CIN1 and CIN2-3 and the only HPV type found in situ and invasive carcinomas. HPV type 51 was found in 21.0% of CIN1 but it was rare in CIN2 and absent in more advanced lesions. 相似文献
10.
Silviene Fabiana De Oliveira Eliane Barbosa Dos Santos Patrícia Jeanne De Souza Mendona Daniela Cristiane Da Cruz Rocha Sidney Emanuel Batista Dos Santos 《American journal of human biology》2001,13(6):718-720
The group‐specific component (GC) system is of interest in anthropological genetic studies because the distribution of its subtypes distinguishes among major ethnic groups. The GC system was analyzed in Curiaú and Pacoval, two remnant Quilombo populations (African‐derived populations) from the Brazilian Amazon. There was no significant statistical difference in allelic frequencies between the two populations or between them and three other African‐derived Brazilian populations (Mimbó, Sítio Velho, and Gaucinha in Northeastern Brazil). These populations share similarities among themselves and with African populations (high frequencies of GC*1F and lower frequencies of GC*1S), which may reflect the influence of a high level of African contribution to their formation, but there is a clear difference between them and Europeans and South American Indians. It is suggested that the GC system is a useful marker for studying relationships between single populations and major ethnic groups, but does not discriminate between populations which share the same parental stock. Am. J. Hum. Biol. 13:718–720, 2001. © 2001 Wiley‐Liss, Inc. 相似文献