全文获取类型
收费全文 | 1094篇 |
免费 | 110篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 44篇 |
妇产科学 | 43篇 |
基础医学 | 160篇 |
口腔科学 | 45篇 |
临床医学 | 133篇 |
内科学 | 202篇 |
皮肤病学 | 11篇 |
神经病学 | 52篇 |
特种医学 | 18篇 |
外科学 | 114篇 |
综合类 | 33篇 |
一般理论 | 1篇 |
预防医学 | 171篇 |
眼科学 | 5篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 95篇 |
出版年
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 20篇 |
2013年 | 29篇 |
2012年 | 51篇 |
2011年 | 53篇 |
2010年 | 31篇 |
2009年 | 28篇 |
2008年 | 37篇 |
2007年 | 42篇 |
2006年 | 44篇 |
2005年 | 32篇 |
2004年 | 35篇 |
2003年 | 40篇 |
2002年 | 30篇 |
2001年 | 33篇 |
2000年 | 45篇 |
1999年 | 27篇 |
1998年 | 12篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1993年 | 19篇 |
1992年 | 33篇 |
1991年 | 23篇 |
1990年 | 24篇 |
1989年 | 32篇 |
1988年 | 16篇 |
1987年 | 22篇 |
1986年 | 27篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 25篇 |
1982年 | 13篇 |
1981年 | 21篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1975年 | 11篇 |
1973年 | 11篇 |
1972年 | 14篇 |
1970年 | 12篇 |
1969年 | 12篇 |
1968年 | 14篇 |
1966年 | 15篇 |
1920年 | 12篇 |
排序方式: 共有1206条查询结果,搜索用时 265 毫秒
1.
2.
3.
Granulocytic sarcoma (chloroma), a rare tumor usually associated with myelogenous leukemia, is capable of invading the meninges or brain parenchyma. Radiologic findings in a case of granulocytic sarcoma of the brain, as well as those in 11 previously reported cases of intracranial leukemic masses, are interpreted. On computed tomographic scans, the lesions can appear isodense or hyperdense, edema and necrosis are variable, and there is uniform enhancement following intravenous administration of contrast material. There may be some affinity for the posterior fossa. 相似文献
4.
People's knowledge of screening tests for which they are eligible and which they may have undergone is frequently low. The aim of the current study is to determine the extent to which this is due to how a test is offered and explained. Routine consultations (n = 102) between midwives, obstetricians and pregnant women were tape-recorded to determine how a routine screening test for fetal abnormalities (maternal serum alpha-fetoprotein) is presented. The test was presented in the vast majority of consultations. Overall, little information was provided about the test, the conditions screened for, and the meaning of either a positive or a negative result. Screening was presented in such a way as to encourage women to undergo the test. The way in which routine prenatal screening is presented is unlikely to maximise informed decisions about whether to participate in this screening programme. Factors likely to be influencing test presentation include knowledge, attitudes and skills of staff, as well as the attitudes of pregnant women. The results of this study highlight a need to train the heath professionals implementing screening programmes in how to inform people fully about low probability but serious events without alarming them unduly, or reassuring them falsely. 相似文献
5.
J W Slack R A Hyndiuk G J Harris K B Simons 《Ophthalmic plastic and reconstructive surgery》1992,8(2):143-149
A 37-year-old man with a recurrent papillomatous lesion of the upper eyelid and four separate bulbar conjunctival ulcers was found to have North American blastomycosis. This represents the first reported case with conjunctival lesions that were not simply contiguous with eyelid involvement. This case underscores the importance of considering blastomycosis in the differential diagnosis of granulomatous conjunctivitis and when examining a lesion of the eyelid resembling a squamous cell carcinoma or atypical papilloma. 相似文献
6.
In order to describe the registrar population and to highlight their problems, a study using an anonymous questionnaire was conducted in August 1988 at the University of Cape Town Group of Teaching Hospitals. The average age of respondents was 32 years and the majority had family responsibilities (60% married, 41% with dependents). They had significant medical experience and postgraduate qualifications. Registrars work long hours (mean 66 +/- 13.7 h/wk), with duty shifts that can extend for up to 34 hours. Most of their time at work was devoted to patient care, with time for study and research virtually non-existent. Although the majority (61%) felt that the 'registrar experience' was worthwhile, a significant proportion of respondents (45%) had considered leaving the rotation. The study revealed several shortcomings that need to be addressed if candidates of good calibre are to be attracted, academic standards are to be maintained and sufficient specialists produced to serve the needs of our population adequately. 相似文献
7.
8.
A prospective study of the bacterial populations of non-infected urine was mounted in an attempt to define the length of delay between voiding and analysis during which culture would not give false positive results due to the multiplication of contaminant bacteria present at the time of voiding. The findings suggest that culture of urine within four hours of voiding is likely to give a true indication of the presence or absence of infection. With further delay the interpretation of a heavy growth of bacteria in urine becomes progressively more unreliable, even if that growth is in pure culture. 相似文献
9.
Use of a non-radioactive hybridisation assay for direct detection of gram-negative bacteria carrying TEM beta-lactamase genes in infected urine 总被引:1,自引:0,他引:1
DNA in infected urines from 81 patients with urinary tract infection was hybridised directly with a non-radioactive DNA probe specific for bacterial genes coding for TEM-type beta-lactamase. The results were assessed by means of a computerised image analysis system and compared with those obtained following isolation of the infecting organism, conventional sensitivity testing and isoelectric focusing (IEF) procedures for the detection of TEM-type beta-lactamase. Of the 27 ampicillin-resistant gram-negative organisms isolated in pure culture from the urines, 14 were shown by both hybridisation and IEF to carry a gene for TEM beta-lactamase production. Only four discordant results were obtained: three "false positive" direct hybridisation results, one due to urine pigmentation, and one, possibly, to a TEM beta-lactamase gene which was not being expressed, and one "false negative" result due to insufficient cell numbers in the urine. The system is capable of screening large numbers of samples and is applicable to any gene for which a suitable DNA probe is available. 相似文献
10.
Betsy R Maller Schulman Aurora Esquela-Kerscher Frank J Slack 《Developmental dynamics》2005,234(4):1046-1054
In C. elegans, heterochronic genes control the timing of cell fate determination during development. Two heterochronic genes, let-7 and lin-4, encode microRNAs (miRNAs) that down-regulate a third heterochronic gene lin-41 by binding to complementary sites in its 3'UTR. let-7 and lin-4 are conserved in mammals. Here we report the cloning and sequencing of mammalian lin-41 orthologs. We find that mouse and human lin-41 genes contain predicted conserved complementary sites for let-7 and the lin-4 ortholog, mir-125, in their 3'UTRs. Mouse lin-41 (Mlin-41) is temporally expressed in developing mouse embryos, most dramatically in the limb buds. Mlin-41 is down-regulated during mid-embryogenesis at the time when mouse let-7c and mir-125 RNA levels are up-regulated. Our results suggest that mammalian lin-41 is temporally regulated by miRNAs in order to direct key developmental events such as limb formation. 相似文献