全文获取类型
收费全文 | 589篇 |
免费 | 37篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 23篇 |
妇产科学 | 11篇 |
基础医学 | 29篇 |
口腔科学 | 7篇 |
临床医学 | 44篇 |
内科学 | 135篇 |
皮肤病学 | 8篇 |
神经病学 | 20篇 |
特种医学 | 84篇 |
外科学 | 139篇 |
综合类 | 42篇 |
预防医学 | 19篇 |
眼科学 | 6篇 |
药学 | 22篇 |
肿瘤学 | 48篇 |
出版年
2023年 | 5篇 |
2022年 | 1篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 24篇 |
2017年 | 17篇 |
2016年 | 15篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 34篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 31篇 |
2009年 | 28篇 |
2008年 | 11篇 |
2007年 | 18篇 |
2006年 | 30篇 |
2005年 | 18篇 |
2004年 | 40篇 |
2003年 | 17篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 21篇 |
1995年 | 28篇 |
1994年 | 16篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 1篇 |
排序方式: 共有638条查询结果,搜索用时 203 毫秒
41.
42.
43.
The role of divalent cations in platelet adherence to deendothelialized human arteries in flowing blood was investigated in an annular perfusion chamber. Spreading of platelets on the subendothelium was impaired below 30 microM of free Ca2+ ions (Ca2+). When Ca2+ was replaced by Mg2+, adherence was unchanged in perfusates without exogenous factor VIII-von Willebrand factor (FVIII-vWF), but the ability of FVIII-vWF to support platelet adherence was lost. Binding of FVIII-vWF to the vessel wall was independent of divalent cations, but bound FVIII-vWF was only able to mediate adherence after exposure to Ca2+. Pretreatment of FVIII-vWF with the calcium chelator EGTA (10 mM) resulted in loss of the ability to facilitate platelet adherence, while the ristocetin cofactor activity remained intact. Full restoration of the ability to mediate platelet adherence could only be obtained by prolonged dialysis against Ca2+ in the millimolar range. These data indicate that divalent cations have at least two separate roles to play in supporting platelet adherence: (1) platelet spreading on the subendothelium requires Ca2+ or Mg2+; (2) FVIII-vWF should be exposed to Ca2+ to obtain its optimal biologic activity in supporting platelet adherence. 相似文献
44.
45.
46.
Between March 1978 and April 1980, the author performed 400 consecutive double eyelid operations in Singapore using Dexon sutures. The results, including various characteristics of the patients, are outlined. There were few complications, and results were good or satisfactory in 98.5% (394) of the cases. 相似文献
47.
Background
Despite its known advantages, breastfeeding rates are low world over. Large number of factors affect breastfeeding. This study was designed to detect maternal and neonatal factors that adversely affect breastfeeding in the perinatal period.Methods
A prospective, single-blinded study was conducted on randomly chosen mother-infant pairs in the maternity ward of a tertiary care service hospital. Only full term singletons born by normal vaginal delivery were studied. The B.R.E.A.S.T observation score and time spent by the infant at the mother''s breast were primary outcome variables. Maternal age, gravida, para status and education level were recorded. Birth weight, sex, gestation age of the infant and time interval from birth to observation were also recorded. Initial univariate analysis followed by multivariate analysis was performed using SPSS ver 7.5 software.Results
A total of 54 mother-infant pairs formed the study group; 19(35.2%) were primigravidas. Primigravidas status of the mother led to significantly lower scores (p<0.04; 95% CI 0.10 to 3.62) as did maternal age < 26 years (p<0.04; 95% CI 0.2. to 3.46) on univariate analysis. Low birth weight (<2500 g) was the only neonatal factor that significantly lowered breastfeeding scores (p<0.02;95%Cl 0.56 to 6.31). On multivariate analysis only primigravida status was significantly associated with lower scores (p<0.02). The alpha value of the study was 5% and the power was 74%. Time spent by infant on breast was not significantly different between primigravida and non-primigravida mothers.Conclusion
Primigravida status adversely affects breastfeeding scores; therefore counseling and support should be focused on this group. Extra care should also be taken to ensure adequate breastfeeding by younger mothers and in those with low birth weight infants. Larger studies with long-term follow up will be able to identify other factors and dertermine the effects of focused counseling and support in the perinatal period upon long-term breastfeeding rates.Key Words: Breastfeeding, Primigravida, Counseling 相似文献48.
Background
The present study was conducted to study the efficacy and toxicity profile of methotrexate chloroquine combination in treatment of active rheumatoid arthritis.Methods
24 patients of rheumatoid arthritis confirming to revised American Rheumatism Association (ARA) criteria were studied prospectively for twenty months. Clinical evaluation was made every 3 months. Clinical disease variables measured at each visit were number of joints with swelling, number of joints with tenderness and pain, duration of morning stiffness and physician and patient assessment of disease activity. Blood counts, liver function tests and other adverse effects due to drugs were monitored every 2 months.Results
10 patients demonstrated more than 50% improvement. 4 patients withdrew from study, 2 because of excessive nausea and vomiting and 2 because of noncompliance. Other side effects noted were hyperpigmentation, photosensitivity, skin rashes, raised transaminases and stomatitis.Conclusion
Methotrexate chloroquine combination has good efficacy and toxicity profile. Gastrointestinal side effects are most common and usually responsible for the discontinuation of the drugs.Key Words: Rheumatoid arthritis, Methotrexate, Chloroquine, Efficacy, Toxicity 相似文献49.
Dermatoglyphic anomalies are hypothesized to indicate disruptions in the second trimester of prenatal development, a time period that appears to be critical in the etiology of schizophrenia. The present study examined the presence of dermatoglyphic anomalies in psychometrically identified schizotypic young adults (n = 51) and control participants (n = 63) selected based upon their scores on the Perceptual Aberration [J. Abnorm. Psychology 87 (1978) 399] and Magical Ideation Scales [J. Consult. Clin. Psychol. 51 (1983) 215]. It was hypothesized that schizotypic participants would exhibit higher rates of dermatoglyphic anomalies than control participants. The Perceptual Aberration-Magical Ideation group exhibited lower total and absolute finger ridge counts and less complex pattern types than control participants--findings consistent with anomalies reported in patients with schizophrenia. These findings encourage future examination of these anomalies in individuals at-risk for schizophrenia and related disorders. 相似文献
50.
Gunn S Hashimoto S Karakozov M Marx T Tan IK Thompson DR Vincent JL 《Critical care (London, England)》2004,8(4):213-218
A young person presents with a highly malignant brain tumour with hemiparesis and limited prognosis after resection. She then suffers an iatrogenic cardiac and respiratory arrest that results in profound anoxic encephalopathy. A difference in opinion between the treatment team and the parent is based on a question of futile therapy. Opinions from five intensivists from around the world explore the differences in ethical and legal issues. A Physician-ethicist comments on the various approaches. 相似文献