全文获取类型
收费全文 | 11501篇 |
免费 | 1000篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 226篇 |
儿科学 | 318篇 |
妇产科学 | 158篇 |
基础医学 | 1356篇 |
口腔科学 | 214篇 |
临床医学 | 1193篇 |
内科学 | 2330篇 |
皮肤病学 | 161篇 |
神经病学 | 1444篇 |
特种医学 | 361篇 |
外科学 | 1416篇 |
综合类 | 265篇 |
一般理论 | 3篇 |
预防医学 | 1097篇 |
眼科学 | 240篇 |
药学 | 891篇 |
中国医学 | 6篇 |
肿瘤学 | 857篇 |
出版年
2021年 | 122篇 |
2020年 | 101篇 |
2019年 | 151篇 |
2018年 | 183篇 |
2017年 | 130篇 |
2016年 | 153篇 |
2015年 | 178篇 |
2014年 | 249篇 |
2013年 | 438篇 |
2012年 | 575篇 |
2011年 | 603篇 |
2010年 | 343篇 |
2009年 | 294篇 |
2008年 | 520篇 |
2007年 | 626篇 |
2006年 | 541篇 |
2005年 | 594篇 |
2004年 | 590篇 |
2003年 | 559篇 |
2002年 | 494篇 |
2001年 | 223篇 |
2000年 | 243篇 |
1999年 | 217篇 |
1998年 | 165篇 |
1997年 | 130篇 |
1996年 | 142篇 |
1995年 | 117篇 |
1994年 | 112篇 |
1993年 | 119篇 |
1992年 | 199篇 |
1991年 | 189篇 |
1990年 | 169篇 |
1989年 | 152篇 |
1988年 | 155篇 |
1987年 | 163篇 |
1986年 | 146篇 |
1985年 | 166篇 |
1984年 | 180篇 |
1983年 | 160篇 |
1982年 | 156篇 |
1981年 | 149篇 |
1980年 | 116篇 |
1979年 | 118篇 |
1978年 | 141篇 |
1977年 | 102篇 |
1976年 | 115篇 |
1975年 | 114篇 |
1974年 | 97篇 |
1973年 | 76篇 |
1968年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Three strains of Campylobacter fetus subsp. fetus isolated from cases of gastroenteritis are reported. DNA-DNA hybridizations in addition to biochemical tests were used to confirm the identification of the isolates as C. fetus since all strains grew at 42 degrees C. These isolates, like other C. fetus strains, are susceptible to cephalothin and thus would not have been detected in laboratories with Campylobacter isolation media containing this component. 相似文献
92.
Laura A Hawryluck William RC Harvey Louise Lemieux-Charles Peter A Singer 《BMC medical ethics》2002,3(1):3-9
Background
Intensivists must provide enough analgesia and sedation to ensure dying patients receive good palliative care. However, if it is perceived that too much is given, they risk prosecution for committing euthanasia. The goal of this study is to develop consensus guidelines on analgesia and sedation in dying intensive care unit patients that help distinguish palliative care from euthanasia.Methods
Using the Delphi technique, panelists rated levels of agreement with statements describing how analgesics and sedatives should be given to dying ICU patients and how palliative care should be distinguished from euthanasia. Participants were drawn from 3 panels: 1) Canadian Academic Adult Intensive Care Fellowship program directors and Intensive Care division chiefs (N = 9); 2) Deputy chief provincial coroners (N = 5); 3) Validation panel of Intensivists attending the Canadian Critical Care Trials Group meeting (N = 12).Results
After three Delphi rounds, consensus was achieved on 16 statements encompassing the role of palliative care in the intensive care unit, the management of pain and suffering, current areas of controversy, and ways of improving palliative care in the ICU.Conclusion
Consensus guidelines were developed to guide the administration of analgesics and sedatives to dying ICU patients and to help distinguish palliative care from euthanasia. 相似文献93.
94.
Five methods for detecting degradation of gelatin by bacteria were compared. These were liquefaction in nutrient broth, hydrolysis in nutrient agar, hydrolysis of charcoal gelatin strips, degradation of the gelatin on strips of photographic film, and alkalinization of gelatin agar. Degradation of photographic film is a rapid and convenient method but, like hydrolysis of gelatin in broth and in agar, may fail to detect weakly positive strains of bacteria. Alkalinization of gelatin in an agar medium is a convenient and sensitive method to detect degradation of gelatin, particularly by Pseudomonas fluorescens, but this method may not be applicable to some species. 相似文献
95.
96.
We analyzed and compared the psychometric properties of two measures of strategiesfor coping with pain:The Coping Strategies Questionnaire (CSQ) and the Cognitive Coping Strategies Inventory (CCSI). The CSQ and CCSI were repeatedly administered to 30 chronic pain patients. Several subscales of both measures showed inadequate internal consistency, and test-retest (one week interval) reliability lower than 0.7. For each inventory, moderate to strong intercorrelations between several subscales were observed. The Catastrophizing subscale was the only subscale for which there was clear evidence of construct validity. Results indicated that both measures showed similar psychometric difficulties, and question the construct validity of subscales other than Catastrophizing. Catastrophizing, however, more closely reflects appraisal processes than a coping strategy per se. We suggest that measures that use more parsimonious and empirically derived coping strategy subscales and that also assess appraisal factors would assist in advancing our understanding of coping with chronic pain. 相似文献
97.
Roest RW Carman WF Maertzdorf J Scoular A Harvey J Kant M Van Der Meijden WI Verjans GM Osterhaus AD 《Journal of medical virology》2004,73(4):601-604
Clinical recurrences of Herpes simplex virus type 1 (HSV-1)-associated genital herpes are thought to be caused by reactivation of latent endogenous HSV-1. However, the possibility of reinfection with exogenous HSV-1 cannot be excluded. This study aimed to determine the incidence of genital HSV-1 superinfection in patients by investigating the genotype of sequential HSV-1 isolates obtained from the same anatomical site of patients with clinical recurrences of genital HSV-1 recurrent genital herpes. Sequential genital HSV-1 isolates were genotyped by PCR amplification of the hypervariable regions located within the HSV-1 genes US1 and US12. Whereas the sequential HSV-1 isolates in 11 of the 13 patients studied had the same genotypes, the sequential isolates of 2 patients showed a different genotype. The data suggest that HSV-1-induced recurrent genital herpes can be associated with genital reinfection with an exogenous HSV-1 strain. 相似文献
98.
An X-linked pattern of transmission observed in four families with familial mental retardation in several generations was associated with a probable secondary constriction at the distal end of the q arms of the X chromosome. Twenty retarded males and no retarded females were observed. All available live retarded males and most of their normal mothers were found to have the abnormal X chromosome. The marker chromosome was shown to be the X chromosome in each case by Giemsa banding. In affected male and female carriers the marker chromosome varied in appearance and was not present in all metaphases. The significance of this study in relation to previously reported pedigrees showing non-specific X-linked mental retardation is discussed. 相似文献
99.
In vitro studies to analyse the pharmacology of histamine-induced dilatation of resistance vessels in rat hindquarters have been made. Histamine caused dose-dependent dilatation of resistance vessels over the concentration range 10–9 to 10–6 mol. Responses to histamine were antagonized by cimetidine but not by mepyramine. Dimaprit also caused vasodilatation. Responses to dimaprit were inhibited by cimetidine 10–6 to 10–5
M. A pA2 of 6.43 (6.11–6.75, 95% confidence limits) was calculated for cimetidine in the resistance vessels of the hindquarters. 相似文献
100.
Lymphatic endothelial cell identity is reversible and its maintenance requires Prox1 activity 总被引:2,自引:0,他引:2
Nicole C. Johnson Miriam E. Dillard Peter Baluk Donald M. McDonald Natasha L. Harvey Sharon L. Frase Guillermo Oliver 《Genes & development》2008,22(23):3282-3291
The activity of the homeobox gene Prox1 is necessary and sufficient for venous blood endothelial cells (BECs) to acquire a lymphatic endothelial cell (LEC) fate. We determined that the differentiated LEC phenotype is a plastic, reprogrammable condition that depends on constant Prox1 activity for its maintenance. We show that conditional down-regulation of Prox1 during embryonic, postnatal, or adult stages is sufficient to reprogram LECs into BECs. Consequently, the identity of the mutant lymphatic vessels is also partially reprogrammed as they acquire some features typical of the blood vasculature. siRNA-mediated down-regulation of Prox1 in LECs in culture demonstrates that reprogramming of LECs into BECs is a Prox1-dependent, cell-autonomous process. We propose that Prox1 acts as a binary switch that suppresses BEC identity and promotes and maintains LEC identity; switching off Prox1 activity is sufficient to initiate a reprogramming cascade leading to the dedifferentiation of LECs into BECs. Therefore, LECs are one of the few differentiated cell types that require constant expression of a certain gene to maintain their phenotypic identity. 相似文献