全文获取类型
收费全文 | 5308篇 |
免费 | 506篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 139篇 |
妇产科学 | 188篇 |
基础医学 | 658篇 |
口腔科学 | 210篇 |
临床医学 | 549篇 |
内科学 | 1054篇 |
皮肤病学 | 222篇 |
神经病学 | 412篇 |
特种医学 | 294篇 |
外国民族医学 | 1篇 |
外科学 | 664篇 |
综合类 | 179篇 |
预防医学 | 498篇 |
眼科学 | 133篇 |
药学 | 335篇 |
中国医学 | 3篇 |
肿瘤学 | 265篇 |
出版年
2022年 | 34篇 |
2021年 | 72篇 |
2020年 | 55篇 |
2019年 | 77篇 |
2018年 | 79篇 |
2017年 | 72篇 |
2016年 | 71篇 |
2015年 | 79篇 |
2014年 | 116篇 |
2013年 | 164篇 |
2012年 | 264篇 |
2011年 | 251篇 |
2010年 | 139篇 |
2009年 | 165篇 |
2008年 | 203篇 |
2007年 | 267篇 |
2006年 | 255篇 |
2005年 | 218篇 |
2004年 | 233篇 |
2003年 | 219篇 |
2002年 | 209篇 |
2001年 | 205篇 |
2000年 | 206篇 |
1999年 | 170篇 |
1998年 | 113篇 |
1997年 | 78篇 |
1996年 | 57篇 |
1995年 | 71篇 |
1994年 | 49篇 |
1993年 | 59篇 |
1992年 | 112篇 |
1991年 | 109篇 |
1990年 | 100篇 |
1989年 | 112篇 |
1988年 | 89篇 |
1987年 | 98篇 |
1986年 | 106篇 |
1985年 | 66篇 |
1984年 | 62篇 |
1983年 | 77篇 |
1982年 | 49篇 |
1981年 | 34篇 |
1980年 | 36篇 |
1979年 | 39篇 |
1978年 | 41篇 |
1975年 | 36篇 |
1973年 | 39篇 |
1971年 | 40篇 |
1970年 | 33篇 |
1969年 | 32篇 |
排序方式: 共有5857条查询结果,搜索用时 15 毫秒
1.
Which infants with eczema are at risk of food allergy? Results from a population‐based cohort 下载免费PDF全文
2.
Association between PCBs and lower embryonic weight in black-crowned night herons in San Francisco Bay 总被引:3,自引:0,他引:3
D J Hoffman B A Rattner C M Bunck A Krynitsky H M Ohlendorf R W Lowe 《Journal of toxicology and environmental health》1986,19(3):383-391
Reproductive problems, including congenital malformations, reduced hatching success, and decreased survival of hatchlings, have been observed in colonial-nesting water birds at the San Francisco Bay National Wildlife Refuge (SFBNWR). Twenty-four black-crowned night heron (Nycticorax nycticorax) eggs were collected from SFBNWR in 1983. Twelve of these were collected from separate nests when late-stage embryos were pipping, and an additional egg was randomly collected from each nest for organochlorine analysis. Overt anomalies and skeletal defects were not apparent. Embryonic weights (with partially absorbed yolk sacs removed) were 15% lower (p less than 0.05) in SFBNWR embryos compared to control embryos from the Patuxent Wildlife Research Center (PWRC). Crown-rump length and femur length were shorter for SFBNWR embryos. The geometric mean polychlorinated biphenyl (PCB) concentration in SFBNWR eggs was 4.1 ppm wet weight, with a range of 0.8-52.0 ppm. A negative correlation (r = -0.61; p less than 0.05) existed between embryonic weight and log-transformed PCB residues in whole eggs collected from the same nest at SFBNWR, suggesting a possible impact of PCBs on embryonic growth. A correlation with embryonic weight did not occur for DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] residues. Liver microsomal aryl hydrocarbon hydroxylase activity was neither significantly elevated nor correlated with PCB, DDE, or PCB plus DDE log-transformed residues. It is unknown whether the apparent association between PCBs and lower weight is persistent through hatching. 相似文献
3.
4.
Relationships of plasma viscosity, coagulation and fibrinolysis to coronary risk factors and angina 总被引:1,自引:0,他引:1
G D Lowe D A Wood J T Douglas R A Riemersma C C Macintyre T Takase E G Tuddenham C D Forbes R A Elton M F Oliver 《Thrombosis and haemostasis》1991,65(4):339-343
Plasma viscosity, molecular markers of activated coagulation and fibrinolysis (fibrinopeptides A and B beta 15-42), coagulation factors (fibrinogen and factor VII) and antiplasmins were measured in 529 men aged 35-54 years and related to new angina pectoris (n = 117) and to coronary risk factors in controls without angina (n = 412). Five major risk factors (cigarette-smoking, blood pressure, cholesterol, triglyceride and body mass index) were each associated with increases in plasma viscosity, coagulation factors, and imbalance of coagulation over fibrinolysis (increased ratio of fibrinopeptide A/fibrinopeptide B beta 15-42). Increased viscosity and fibrinogen in smokers were partly reversed in ex-smokers, but the imbalance of coagulation and fibrinolysis persisted. Cholesterol and triglyceride were also associated with increased antiplasmin activity. In men with angina, only fibrinogen was elevated compared to controls. We suggest that increased plasma viscosity and an imbalance of coagulation over fibrinolysis may be mechanisms by which known risk factors promote arterial thrombosis, but are not present in stable angina. 相似文献
5.
6.
We have compared the effects of acetyl salicylic acid (ASA, aspirin) and choline magnesium trisalicylate (CMT), a non-acetylated salicylate product, on platelet aggregation in human whole blood ex-vivo. Using a whole blood platelet counter, platelet aggregation was quantified by measuring the fall in the number of single platelets at peak aggregation in response to collagen, arachidonic acid (AA), as well as spontaneous aggregation. In double blind and random order, 12 healthy volunteers received, on two separate occasions 10 days apart, a single oral dose of 652 mg ASA or 655 mg CMT. Despite a comparable absorption of salicylic acid from the two drugs, ingestion of ASA resulted in a marked inhibition of platelet aggregation induced by collagen (p less than 0.005), AA (p less than 0.01) and spontaneous aggregation (p less than 0.01), whereas such effects were not observed after CMT ingestion. We suggest that CMT may have therapeutic potential as an alternative to aspirin when inhibition of platelet aggregation can induce bleeding complications. 相似文献
7.
目的由于卒中风险随着狭窄严重程度的增加而升高,因此认为颈内动脉(ICA)接近闭塞患者的卒中风险很高。在现有的随机试验中,还没有专门针对这种情况进行探讨,因此其处理尚存在争汶。方法:对相关文献进行系统评价。结果:对ICA接近闭塞患者的处理还存在争议:一些学者支持进行干预,而另一些学者则认为存在风险或没有益处而反对进行干预。在ICA接近闭塞的有症状患者中进行一项比较外科治疗与最佳内科治疗的多中心前瞻性随机试验似乎非常困难,因为这类研究需要大量的患者。尽管如此,基于目前的证据,似乎很难拒绝手术治疗。结论:由于目前对ICA接近闭塞患者的最佳处理方案仍存在着争议,因此需要前瞻性观察性研究以证实其在有症状和无症状人群中的患病率以及相关的卒中风险。基于目前的证据,大多数医疗中心选择手术治疗,但它相对干内科治疗的特粱尚右待证章. 相似文献
8.
9.
Predictors, costs and characteristics of out of area placement for people with intellectual disability and challenging behaviour 总被引:1,自引:0,他引:1
D. G. Allen K. Lowe K. Moore & S. Brophy 《Journal of intellectual disability research : JIDR》2007,51(6):409-416
Background Out of area placements for people with challenging behaviour represent an expensive and often ineffective strategy for meeting the needs of this service user group. Methods More than 800 agencies and service settings in a large area of South Wales were screened to identify children and adults with challenging behaviour against a number of defined operational criteria. Detailed data on identified individuals and the services they received were collected by interviewing key informants. Univariate and multivariate statistics were employed to identify predictors of out of area placement. Results In total, 1458 people were identified. Full data were available for 901 participants, 97 of whom were placed out of area. Predictors of out of area placement included behaviours resulting in physical injury and exclusion from service settings, a history of formal detention under the mental health act, the presence of mental health problems, a diagnosis of autism and higher total score on the Adaptive Behaviour Scale. Out of area placements were typically of high cost, and associated with only limited evidence of improved service quality. Conclusions Identifying predictors for out of area placement can be used to highlight deficiencies in local services and individuals at increased risk of exclusion from local services. 相似文献
10.