全文获取类型
收费全文 | 7734篇 |
免费 | 520篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 260篇 |
妇产科学 | 136篇 |
基础医学 | 1010篇 |
口腔科学 | 77篇 |
临床医学 | 1168篇 |
内科学 | 1262篇 |
皮肤病学 | 92篇 |
神经病学 | 663篇 |
特种医学 | 163篇 |
外国民族医学 | 1篇 |
外科学 | 912篇 |
综合类 | 95篇 |
一般理论 | 2篇 |
预防医学 | 996篇 |
眼科学 | 92篇 |
药学 | 527篇 |
中国医学 | 2篇 |
肿瘤学 | 748篇 |
出版年
2023年 | 68篇 |
2022年 | 87篇 |
2021年 | 261篇 |
2020年 | 145篇 |
2019年 | 198篇 |
2018年 | 216篇 |
2017年 | 167篇 |
2016年 | 168篇 |
2015年 | 197篇 |
2014年 | 243篇 |
2013年 | 346篇 |
2012年 | 556篇 |
2011年 | 545篇 |
2010年 | 274篇 |
2009年 | 303篇 |
2008年 | 444篇 |
2007年 | 477篇 |
2006年 | 464篇 |
2005年 | 476篇 |
2004年 | 402篇 |
2003年 | 404篇 |
2002年 | 345篇 |
2001年 | 114篇 |
2000年 | 93篇 |
1999年 | 100篇 |
1998年 | 85篇 |
1997年 | 56篇 |
1996年 | 73篇 |
1995年 | 61篇 |
1994年 | 69篇 |
1993年 | 66篇 |
1992年 | 69篇 |
1991年 | 59篇 |
1990年 | 57篇 |
1989年 | 40篇 |
1988年 | 43篇 |
1987年 | 50篇 |
1986年 | 32篇 |
1985年 | 40篇 |
1984年 | 60篇 |
1983年 | 36篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1976年 | 20篇 |
1974年 | 17篇 |
1972年 | 13篇 |
1970年 | 12篇 |
排序方式: 共有8273条查询结果,搜索用时 31 毫秒
1.
2.
3.
Janette B Gomos Theresa M Rowe Saumendra N Sarkar Sean P Kessler Ganes C Sen 《Journal of interferon & cytokine research》2002,22(2):199-206
The 9-2 isozyme of 2-5 (A) synthetase has cellular proapoptotic functions that are mediated not by enzyme activity but by the Bcl-2 homology domain 3 present in its unique carboxyl-terminal region. Another proapoptotic cellular protein is Bax, whose absence in the Bax(-/-) mice causes male sterility due to abnormal sperm differentiation. In this study, we examined whether transgenic 9-2 expression can substitute for the in vivo reproductive function of Bax. To achieve this goal, a sperm-specific promoter was used to drive the expression of 9-2 in the sperm of transgenic mice. By selective cross-breeding, the transgene was transferred to Bax(-/-) mice to generate the experimental mouse line (Bax(-/-), 9-2(+/+)). The male experimental mice were sterile, and their testes maintained the structural abnormality found in Bax(-/-) mice. Thus, the male reproduction functions of Bax could not be replaced by the 9-2 isozyme of 2-5 (A) synthetase. 相似文献
4.
Over the last several decades the idea that adenosine (Ado) plays a role in sleep control was postulated due in large part to pharmacological studies that showed the ability of Ado agonists to induce sleep and Ado antagonists to decrease sleep. A second wave of research involving in vitro cellular analytic approaches and subsequently, the use of neurochemical tools such as microdialysis, identified a population of cells within the brainstem and basal forebrain arousal centers, with activity that is both tightly coupled to thalamocortical activation and under tonic inhibitory control by Ado. Most recently, genetic tools have been used to show that Ado receptors regulate a key aspect of sleep, the slow wave activity expressed during slow wave sleep. This review will briefly introduce some of the phenomenology of sleep and then summarize the effect of Ado levels on sleep, the effect of sleep on Ado levels, and recent experiments using mutant mouse models to characterize the role for Ado in sleep control and end with a discussion of which Ado receptors are involved in such control. When taken together, these various experiments suggest that while Ado does play a role in sleep control, it is a specific role with specific functional implications and it is one of many neurotransmitters and neuromodulators affecting the complex behavior of sleep. Finally, since the majority of adenosine-related experiments in the sleep field have focused on SWS, this review will focus largely on SWS; however, the role of adenosine in REM sleep behavior will be addressed. 相似文献
5.
6.
7.
Acellular Pertussis Vaccine Protects against Exacerbation of Allergic Asthma Due to Bordetella pertussis in a Murine Model 下载免费PDF全文
Darren P. Ennis Joseph P. Cassidy Bernard P. Mahon 《Clinical and Vaccine Immunology : CVI》2005,12(3):409-417
The prevalence of asthma and allergic disease has increased in many countries, and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether acellular pertussis vaccine (Pa) enhanced or prevented B. pertussis-induced exacerbation of allergic asthma. Groups of mice were immunized with Pa, infected with B. pertussis, and/or sensitized to ovalbumin. Immunological, pathological, and physiological changes were measured to assess the impact of immunization on immune deviation and airway function. We demonstrate that immunization did not enhance ovalbumin-specific serum immunoglobulin E production. Histopathological examination revealed that immunization reduced the severity of airway pathology associated with sensitization in the context of infection and decreased bronchial hyperreactivity upon methacholine exposure of infected and sensitized mice. These data demonstrate unequivocally the benefit of Pa immunization to health and justify selection of Pa in mass vaccination protocols. In the absence of infection, the Pa used in this study enhanced the interleukin-10 (IL-10) and IL-13 responses and influenced airway hyperresponsiveness to sensitizing antigen; however, these data do not suggest that Pa contributes to childhood asthma overall. On the contrary, wild-type virulent B. pertussis is still circulating in most countries, and our data suggest that the major influence of Pa is to protect against the powerful exacerbation of asthma-like pathology induced by B. pertussis. 相似文献
8.
Meike Lippelt Theresa Sanabria de Isele Manfred Kist 《Clinical microbiology and infection》1997,3(2):229-235
Objective: To carry out an epidemiologic evaluation of Salmonella enterica subsp. enterica serovar Enteritidis outbreaks in households and small communities by means of rRNA gene restriction pattern analysis (ribotyping).
Method: One hundred Enteritidis isolates dating from 1989 to 1994 which could be allocated epidemiologically to different sources or to small community outbreaks were investigated with ribotyping, a fingerprinting method in which bacterial DNA is hybridized with the biotin-labeled plasmid pKK 3535 containing a ribosomal RNA operon of Escherichia coli to determine the ribosomal RNA gene restriction patterns.
Results: Four different ribotyping patterns were found with the restriction endonuclease Sma I and nine with Sph I. Ribotypes of isolates which could be allocated epidemiologically to a common source usually corresponded. Almost 60% of the Enteritidis infections had the ribotyping pattern Sph I-A. In contrast, this pattern was not found in any of the five Enteritidis strains isolated in 1989. The suspicion that Enteritidis phage type 4 infections are caused by consumption of insufficiently heated eggs is supported by the fact that the ribotyping pattern Sph 1-A was found in isolates from eggs and from human specimens.
Conclusions: As patterns Sph I-A and Sma I-J appeared in 58% and 75% of the isolates, respectively, ribotyping cannot be used for the differentiation between various outbreaks with these two patterns. In cases where the Enteritidis strains showed less frequent patterns, ribotyping seems to be a practical tool for the identification of infection chains. In addition newly appearing ribotyping patterns can give information about the epidemiologic development of Enteritidis infection. 相似文献
Method: One hundred Enteritidis isolates dating from 1989 to 1994 which could be allocated epidemiologically to different sources or to small community outbreaks were investigated with ribotyping, a fingerprinting method in which bacterial DNA is hybridized with the biotin-labeled plasmid pKK 3535 containing a ribosomal RNA operon of Escherichia coli to determine the ribosomal RNA gene restriction patterns.
Results: Four different ribotyping patterns were found with the restriction endonuclease Sma I and nine with Sph I. Ribotypes of isolates which could be allocated epidemiologically to a common source usually corresponded. Almost 60% of the Enteritidis infections had the ribotyping pattern Sph I-A. In contrast, this pattern was not found in any of the five Enteritidis strains isolated in 1989. The suspicion that Enteritidis phage type 4 infections are caused by consumption of insufficiently heated eggs is supported by the fact that the ribotyping pattern Sph 1-A was found in isolates from eggs and from human specimens.
Conclusions: As patterns Sph I-A and Sma I-J appeared in 58% and 75% of the isolates, respectively, ribotyping cannot be used for the differentiation between various outbreaks with these two patterns. In cases where the Enteritidis strains showed less frequent patterns, ribotyping seems to be a practical tool for the identification of infection chains. In addition newly appearing ribotyping patterns can give information about the epidemiologic development of Enteritidis infection. 相似文献
9.
A model for training the trainers of child care providers that employs Vygotsky's framework of the Zone of Proximal Development is described. This efficient training mechanism proposes mentoring relationships as a means to meet the developmental needs of experienced child care professionals and improve the quality of existing child care programs.The authors would like to thank Dr. Bille Thomas and the satellite resource center directors and staff members for their work on the project. 相似文献
10.
Anil S Paramesh Ralph B Fairchild Theresa M Quinn Fred Leya Magdalene George David H Van Thiel 《Liver transplantation》2005,11(2):236-238
A 53-year-old male with hepatitis C cirrhosis, who had been refused liver transplantation because of hypertrophic cardiomyopathy (HC), underwent nonsurgical septal ablation using alcohol with resolution of his ventricular outflow obstruction. This patient was able to subsequently undergo a successful deceased donor liver transplantation. This is the first reported case of alcohol induced septal ablation being performed in a cirrhotic patient with HC. Such nonsurgical procedures may be attractive in cirrhotic patients who are refused access to liver transplantation because of high surgical risk. 相似文献