全文获取类型
收费全文 | 350篇 |
免费 | 28篇 |
国内免费 | 41篇 |
专业分类
儿科学 | 44篇 |
妇产科学 | 4篇 |
基础医学 | 66篇 |
口腔科学 | 8篇 |
临床医学 | 40篇 |
内科学 | 63篇 |
皮肤病学 | 3篇 |
神经病学 | 7篇 |
特种医学 | 53篇 |
外科学 | 16篇 |
综合类 | 16篇 |
预防医学 | 67篇 |
眼科学 | 4篇 |
药学 | 16篇 |
中国医学 | 1篇 |
肿瘤学 | 11篇 |
出版年
2023年 | 2篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 11篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 4篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 33篇 |
2006年 | 14篇 |
2005年 | 19篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 16篇 |
1997年 | 30篇 |
1996年 | 23篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
41.
A large nursing home corporation implemented a safe resident handling program (SRHP) in 2004-2007. We evaluated its efficacy over a 2-year period by examining differences among 5 centers in program outcomes and potential predictors of those differences. We observed nurs-ing assistants (NAs), recording activities and body postures at 60-second intervals on personal digital assistants at baseline and at 3-month, 12-month, and 24-month follow-ups. The two outcomes computed were change in equipment use during resident handling and change in a physical workload index that estimated spinal loading due to body postures and handled loads. Potential explanatory factors were extracted from post-observation interviews, investigator surveys of the workforce, from administrative data, and employee satisfaction surveys. The facility with the most positive outcome measures was associated with many positive changes in explanatory factors and the facility with the fewest positive outcome measures experienced negative changes in the same factors. These findings suggest greater SRHP benefits where there was lower NA turnover and agency staffing; less time pressure; and better teamwork, staff communication, and supervisory support. 相似文献
42.
Increased expression of the G gamma and A gamma globin genes associated with a mutation in the A gamma enhancer 总被引:1,自引:0,他引:1
Balta G; Brickner HE; Takegawa S; Kazazian HH Jr; Papayannopoulou T; Forget BG; Atweh GF 《Blood》1994,83(12):3727-3737
We have previously described a unique type of delta beta-thalassemia in a Chinese family characterized by increased expression of the G gamma and A gamma fetal globin genes in the absence of a large deletion in the beta-globlin gene cluster. Our earlier study of the beta-globin gene on this delta beta-thalassemia chromosome showed a promoter mutation in the TATA box. In this report, we describe the results of our study of the fetal globin domain of this delta beta-thalassemia chromosome. We have cloned a 13-kb DNA fragment that includes the G gamma and the A gamma genes and the 3' A gamma enhancer element of this delta beta-thalassemia chromosome. DNA sequence analysis of the G gamma and A gamma-globin genes including their promoters did not show any mutations, but analysis of the putative enhancer element downstream from the A gamma-globin gene showed a C to T substitution 2,401 nucleotides downstream from the A gamma cap site. We performed DNA linkage analysis to determine if this mutation is unique to this chromosome or represents a common polymorphism. Our linkage analysis showed that this mutation is not a common polymorphism and that it is also not an intrinsic part of the haplotype of the chromosome on which it was found. We also studied the interaction of nuclear proteins from erythroid and nonerythroid cells with the DNA sequences surrounding this mutation. We have shown by in vitro DNase I footprinting that this mutation falls within a region that is occupied by a novel DNA-binding protein that binds to this site in nuclear extracts from erythroid, but not nonerythroid cells. The binding of this nuclear protein to DNA appears to be dependent on GATA-1 binding to an adjacent GATA-1 site. We have also developed a new functional assay to compare the activity of the normal and mutant A gamma enhancer elements in erythroid cells. Analysis of the activity of the mutant enhancer shows that the mutation completely eliminates all enhancer activity in this assay. These findings suggest that this mutation of the A gamma enhancer on a chromosome that carries a partially inactivated beta-globin gene may be responsible for the increased expression of both gamma-globin genes seen in this condition. 相似文献
43.
This study described the binding of platelet plasma membranes to either control or thrombin-activated platelets. Glycoproteins in plasma membranes isolated from human platelets were labeled by oxidation with periodate followed by reduction with [3H]NaBH4. Labeled membranes were incubated with either control or thrombin-activated platelets. The amount of membranes bound was measured by separating platelets with bound membranes from solution by rapid centrifugation through 27% sucrose and determining the amount of radioactivity associated with platelets. Five- to sevenfold more membranes bound to thrombin- activated platelets than to control platelets. This enhanced binding of labeled membranes was completely inhibited by an excess of unlabeled platelet membranes. Human erythrocyte membranes had little affinity for either washed or thrombin-activated platelets and therefore did not compete for platelet-membrane binding. Binding of platelet membranes to thrombin-treated platelets was inhibited by prior incubation of the platelets with PGI2 suggesting that the enhanced binding of membranes was to activated platelets. This study demonstrates that the purified platelet membranes have functional sites that can mediate membrane binding to platelets and that quantitation of membrane binding appears to reflect the increased aggregation capability of activated platelets. 相似文献
44.
45.
46.
47.
Neil R Price Amanda Charlton Itayi Simango Grahame HH Smith 《Journal of paediatrics and child health》2014,50(10):E102-E105
Aim: To explore the issue of appropriate management of testicular microlithiasis. We report the third ever case of tumour arising from a testis previously known to have microlithiasis in childhood and review the literature to provide an evidence‐based approach to management of testicular microlithiasis. Methods: Case report and review of previous literature. Results and Conclusions: Although there is a strong association between testicular microlithiasis and testicular malignancy at diagnosis, there are only three reported cases of subsequent tumour development in childhood. Testicular microlithiasis is an increasingly recognised entity. There is insufficient evidence in the current literature to support any regime of clinical surveillance. Self‐examination is the most important factor in the early detection of testicular malignancy. 相似文献
48.
Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers 总被引:2,自引:2,他引:0
Holcomb HH; Medoff DR; Caudill PJ; Zhao Z; Lahti AC; Dannals RF; Tamminga CA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(6):534-542
Tone recognition is partially subserved by neural activity in the right
frontal and primary auditory cortices. First we determined the brain areas
associated with tone perception and recognition. This study then examined
how regional cerebral blood flow (rCBF) in these and other brain regions
correlates with the behavioral characteristics of a difficult tone
recognition task. rCBF changes were assessed using H2(15)O positron
emission tomography. Subtraction procedures were used to localize
significant change regions and correlational analyses were applied to
determine how response times (RT) predicted rCBF patterns. Twelve trained
normal volunteers were studied in three conditions: REST, sensory motor
control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral
activation of primary auditory cortices, cerebellum and bilateral inferior
frontal gyri. DEC-SMC produced significant clusters in the right middle and
inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus
and supplementary motor area; the left insula/claustrum; and the left
cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a
positive correlation in right inferior and middle frontal cortex; rCBF in
bilateral auditory cortices and cerebellum exhibited significant negative
correlations with RT These changes suggest that neural activity in the
right frontal, superior temporal and cerebellar regions shifts back and
forth in magnitude depending on whether tone recognition RT is relatively
fast or slow, during a difficult, accurate assessment.
相似文献
49.
50.