全文获取类型
收费全文 | 21112篇 |
免费 | 1760篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 139篇 |
儿科学 | 790篇 |
妇产科学 | 569篇 |
基础医学 | 2718篇 |
口腔科学 | 276篇 |
临床医学 | 2373篇 |
内科学 | 4073篇 |
皮肤病学 | 332篇 |
神经病学 | 2266篇 |
特种医学 | 392篇 |
外国民族医学 | 5篇 |
外科学 | 2366篇 |
综合类 | 252篇 |
一般理论 | 67篇 |
预防医学 | 2979篇 |
眼科学 | 284篇 |
药学 | 1461篇 |
1篇 | |
中国医学 | 43篇 |
肿瘤学 | 1528篇 |
出版年
2024年 | 36篇 |
2023年 | 268篇 |
2022年 | 430篇 |
2021年 | 984篇 |
2020年 | 581篇 |
2019年 | 822篇 |
2018年 | 920篇 |
2017年 | 663篇 |
2016年 | 694篇 |
2015年 | 755篇 |
2014年 | 984篇 |
2013年 | 1292篇 |
2012年 | 1788篇 |
2011年 | 1802篇 |
2010年 | 932篇 |
2009年 | 769篇 |
2008年 | 1296篇 |
2007年 | 1376篇 |
2006年 | 1116篇 |
2005年 | 1041篇 |
2004年 | 962篇 |
2003年 | 867篇 |
2002年 | 644篇 |
2001年 | 149篇 |
2000年 | 121篇 |
1999年 | 125篇 |
1998年 | 141篇 |
1997年 | 103篇 |
1996年 | 64篇 |
1995年 | 74篇 |
1994年 | 60篇 |
1993年 | 57篇 |
1992年 | 65篇 |
1991年 | 49篇 |
1990年 | 71篇 |
1989年 | 57篇 |
1988年 | 49篇 |
1987年 | 44篇 |
1986年 | 37篇 |
1985年 | 45篇 |
1984年 | 36篇 |
1982年 | 30篇 |
1981年 | 39篇 |
1980年 | 34篇 |
1979年 | 43篇 |
1977年 | 29篇 |
1974年 | 29篇 |
1973年 | 28篇 |
1972年 | 31篇 |
1971年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
31.
Irene T Lynch Joseph A Eustace Willliam D Plant Kevin D Cashman Majella O'Keefe Sinead Lordan Rachel Moloney 《Journal of renal nutrition》2007,17(6):408-415
OBJECTIVE: To quantify the dietary calcium and vitamin D intake in adult renal-transplant recipients attending at a large teaching hospital in Ireland for follow-up. SETTING: Outpatient renal-transplant follow-up clinic. SUBJECTS: Fifty-nine adult renal transplant recipients (58% male) with a mean age of 46 years, a median transplant duration of 6 years, and a mean estimated glomerular filtration rate (eGFR) of 50 mL/min per 1.73 m2. Fifty-three percent were at National Kidney Foundation stage 3 chronic kidney disease, and 14% had stage 4 chronic kidney disease. INTERVENTION: This cross-sectional, observational study used a tailored food frequency questionnaire specific for calcium and vitamin D intake in Irish adults, which was completed during a face-to-face interview with each subject. MAIN OUTCOME MEASURE: The main outcome measure was the average daily dietary and supplemented calcium and vitamin D intake. RESULTS: The median interquartile range (IQR) dietary calcium intake was 820 mg/day (range, 576-1,177 mg/day), and was similar in men and women (recommended intake > or = 1,000 mg/day in adult men and nonmenopausal adult women, > or = 1,500 mg/day in menopausal women). Five participants received calcium supplementation. Overall, 59% of men and 64% of women had total calcium intakes below the recommended amounts. The median IQR estimated dietary vitamin D intake was 5.2 microg/day (range, 2.4-6.4 microg/day) in women, and 4.6 microg/day (range, 2.2-6.6 microg/day) in men (recommended intake, > or = 10 microg/day). Six subjects received vitamin D supplementation. Total vitamin D intakes were suboptimal in 91% of men and 87% of women. Dietary calcium and vitamin D intakes significantly correlated with each other, but neither was significantly related to eGFR category, and was similarly low in both presumed menopausal women and in the initial year posttransplantation. CONCLUSION: These findings suggest that dietary and total calcium and vitamin D intakes in adult renal-transplant patients are in many cases inadequate. 相似文献
32.
Differences in blood pregnenolone and dehydroepiandrosterone levels between schizophrenia patients and healthy subjects. 总被引:1,自引:0,他引:1
Michael Ritsner Rachel Maayan Anatoly Gibel Abraham Weizman 《European neuropsychopharmacology》2007,17(5):358-365
BACKGROUND AND OBJECTIVE: Contradictory and confusing reports on serum dehydroepiandrosterone (DHEA) levels in schizophrenia led us to compare the serum concentration of its precursor, pregnenolone (PREG), between medicated schizophrenia patients and healthy subjects. The neurosteroid levels were monitored for two months and the relationship of these neurosteroids with schizophrenic symptomatology, emotional distress, and anxiety was examined. METHOD: We determined blood levels of PREG, and DHEA in 15 schizophrenia patients and 12 healthy controls at four time points: at the start of the study, after 2, 4 and 8 weeks. Analysis of covariance and canonical correlations across four time points were applied. RESULTS: Controlling for age, serum concentrations of PREG were lower, while the DHEA level and the molar ratio values of DHEA/PREG were higher in schizophrenia patients compared to healthy controls. Both levels of PREG and DHEA and their molar ratio did not change significantly during the study's period either among schizophrenia patients or healthy controls. The blood levels of PREG appear to be associated with trait-anxiety scores in the schizophrenia patients, while associations of clinical symptoms with two neurosteroids did not reach a significant level when the confounding effect of emotional distress, and anxiety scores was controlled. CONCLUSION: Low serum pregnenolone concentrations in schizophrenia appear to be associated with trait-anxiety scores independent of symptoms. Further research into the role of pregnenolone in schizophrenia is warranted. 相似文献
33.
Kevin G Becker Insong J Lee James W Nagle Rachel D Canning Ameer M Gado Rosarelis Torres Mihael H Polymeropoulos Paul T Massa WilliamE Biddison Paul D Drew 《International journal of developmental neuroscience》1997,15(7):73
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function. 相似文献
34.
Ladenstein Ruth; Pearce Rachel; Hartmann Olivier; Patte Catherine; Goldstone Tony; Philip Thierry 《Blood》1997,90(8):2921-2930
35.
There is growing interest in the phenomenon of long-term depression (LTD) of synaptic efficacy that, together with long-term potentiation (LTP), is a putative information storage mechanism in mammalian brain. In neural network models, multiple learning rules have been used for LTD induction. Similarly, in neurophysiological studies of hippocampal synaptic plasticity, a variety of activity patterns have been effective at inducing LTD, although experimental paradigms are still being optimized. In this review the authors summarize the major experimental paradigms and compare what is known about the mechanisms of LTD induction. Although all paradigms appear to initiate a cascade of events leading to an elevated level of Ca2+ postsynaptically, the extent to which these paradigms involve common expression mechanisms has not yet been tested. The authors discuss several critical experiments that would address this latter issue. Numerous questions about the properties and mechanisms of LTD(s) in the hippocampus remain to be answered, but it is clear that LTD has finally arrived, and will soon be attracting attention equal to its flip side, LTP. © 1994 Wiley-Liss, Inc. 相似文献
36.
37.
Christie AB 《Postgraduate medical journal》1949,25(287):409-412
38.
Suresh Kumar Masilamani Annamalai Rachel Buckingham John Cashman 《Journal of children's orthopaedics》2007,1(2):107-113
The treatment of Legg-Calvé-Perthes disease remains controversial. The aim of this survey was to ascertain the current management
strategies of this condition amongst UK paediatric orthopaedic surgeons, with particular regard to containment procedures
in the fragmentation phase. Questionnaires were distributed at the January 2006 meeting of the British Society for Children’s
Orthopaedic Surgery (BSCOS) and was posted to all absent members. The results showed a great deal of variability not only
in the treatment of Perthes disease, but also in the decision-making processes. Consideration must now be given to a carefully
constructed national multi-centre prospective randomised controlled study into the optimum management of this disease 相似文献
39.
Rachel M Massey Oliver J Warren Michal Szczeklik Sophie Wallace Daniel R Leff John Kokotsakis Ara Darzi Thanos Athanasiou 《Journal of cardiothoracic surgery》2007,2(1):26-9
The use of a skeletonized internal thoracic artery in coronary artery bypass graft surgery has been shown to confer certain
advantages over a traditional pedicled technique, particularly in certain patient groups. Recent reports indicate that radial
and gastroepiploic arteries can also be harvested using a skeletonized technique. The aim of this study is to systematically
review the available evidence regarding the use of skeletonized radial and gastroepiploic arteries within coronary artery
bypass surgery, focusing specifically on it's effect on conduit length and flow, levels of endothelial damage, graft patency
and clinical outcome. Four electronic databases were systematically searched for studies reporting the utilisation of the
skeletonization technique within coronary revascularisation surgery in humans. Reference lists of all identified studies were
checked for any missing publications. There appears to be some evidence that skeletonization may improve angiographic patency,
when compared with pedicled vessels in the short to mid-term. We have found no suggestion of increased complication rates
or increased operating time. Skeletonization may increase the length of the conduit, and the number of sequential graft sites,
but no clear clinical benefits are apparent. Our study suggests that there is not enough high quality or consistent evidence
to currently advocate the application of this technique to radial or gastroepiploic conduits ahead of a traditional pedicled
technique. 相似文献
40.