全文获取类型
收费全文 | 3217篇 |
免费 | 215篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 81篇 |
妇产科学 | 62篇 |
基础医学 | 356篇 |
口腔科学 | 31篇 |
临床医学 | 404篇 |
内科学 | 492篇 |
皮肤病学 | 42篇 |
神经病学 | 371篇 |
特种医学 | 135篇 |
外科学 | 487篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 311篇 |
眼科学 | 119篇 |
药学 | 253篇 |
1篇 | |
肿瘤学 | 254篇 |
出版年
2023年 | 15篇 |
2022年 | 55篇 |
2021年 | 103篇 |
2020年 | 58篇 |
2019年 | 98篇 |
2018年 | 126篇 |
2017年 | 79篇 |
2016年 | 75篇 |
2015年 | 80篇 |
2014年 | 120篇 |
2013年 | 210篇 |
2012年 | 246篇 |
2011年 | 267篇 |
2010年 | 166篇 |
2009年 | 142篇 |
2008年 | 218篇 |
2007年 | 205篇 |
2006年 | 200篇 |
2005年 | 164篇 |
2004年 | 160篇 |
2003年 | 154篇 |
2002年 | 133篇 |
2001年 | 33篇 |
2000年 | 18篇 |
1999年 | 20篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 20篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1973年 | 5篇 |
1969年 | 5篇 |
1968年 | 8篇 |
1967年 | 9篇 |
1966年 | 11篇 |
排序方式: 共有3442条查询结果,搜索用时 15 毫秒
41.
Parisa Aminzadeh Ekaterina Alibrahim Andrew Dobrotwir Eldho Paul Stacy Goergen 《The British journal of radiology》2021,94(1119)
Objective:To assess accuracy of and interobserver agreement on multiparametric MR findings to distinguish uterine leiomyoma (LM) from uterine leiomyosarcoma (LMS) and soft tissue tumour of unknown malignant potential.Methods:Inclusion criteria: All females over 18 years with least one uterine mass measuring 5 cm or more in at least one of the three standard orthogonal dimensions on MR with histopathological confirmation of LM, LMS, or soft tissue tumour of unknown malignant potential (STUMP) in the 3 months following MR. Patients with LMS were drawn from a larger cohort being assessed for MR-guided focussed ultrasound (MRgFUS) suitability. Image evaluation: Assessed variables were: lesion margin, margin definition, T2 signal homogeneity, >50% of lesion with T2 signal brighter than myometrium, haemorrhage, restricted diffusion, contrast enhancement (CE), CE pattern, local lymphadenopathy and ascites.Results:32 LM, 10 LMS and 1 STUMP were evaluated. Ill-defined (p-value = 0.0003–0.0004) or irregular (p = 0.003–0.004) lesion margin, T2 hyperintensity >50% (p = 0.001–0.004), and peripheral CE (p = 0.02–0.05) were significantly more common in LMS/STUMP than LM for both radiologists. 10/11 (Reader 2) and 11/11 (Reader 1) LMS/STUMP displayed restricted diffusion but so did 63–80% of LM. Agreement was greatest for margin characteristics (κ = 0.73–0.81).Conclusion:Irregular/ill-defined lesion margin best distinguished LMS/STUMP from LM with good interrater reliability.Advances in knowledge:Assessment of agreement regarding MR parameters distinguishing LM from LMS and STUMP has not previously been undertaken in a cohort including a large number of patients with LMS. This will help inform evaluation of females considering minimally invasive LM treatment. 相似文献
42.
43.
44.
Hemostatic gene polymorphisms and the prevalence of thrombotic complications in polycythemia vera and essential thrombocythemia. 总被引:3,自引:0,他引:3
Vahid Afshar-Kharghan José A López Leigh A Gray Arnoldo Padilla Gautam Borthakur Stacy C Roberts Rajiv K Pruthi Ayalew Tefferi 《Blood coagulation & fibrinolysis》2004,15(1):21-24
Patients with polycythemia vera and essential thrombocythemia are at risk for thrombotic and bleeding complications. Currently, no diagnostic test can predict thrombohemorrhagic complications. In a prospective study of 86 patients with polycythemia vera (43 patients) or essential thrombocythemia (43 patients), we examined the possible role of polymorphisms of platelet adhesion receptors [glycoprotein (GP) Ibalpha, GPIa, GPIIIa) and clotting factor II (prothrombin's G20210A mutation) and clotting factor V (Leiden mutation) in determining the risk of thrombotic or bleeding complications. Except for an association between vasomotor symptoms and prothrombin mutation (P < 0.001), no significant correlation between polymorphism of clotting factors and thrombohemorrhagic complications was identified. When the entire patient cohort was considered, the polymorphisms of platelet adhesion receptors were not associated with the risk for thrombotic or bleeding complications. However, among patients with polycythemia vera, the presence of the PlA2 allele of GPIIIa was associated with an increased risk of arterial thrombosis. In view of previous studies linking the presence of the PlA2 allele of GPIIIa to a higher risk for coronary artery thrombosis, our data have physiologic relevance. However, they need to be confirmed in a larger study. 相似文献
45.
46.
47.
Placental expression of soluble fms-like tyrosine kinase 1 is increased in singletons and twin pregnancies with intrauterine growth restriction 总被引:1,自引:0,他引:1
Nevo O Many A Xu J Kingdom J Piccoli E Zamudio S Post M Bocking A Todros T Caniggia I 《The Journal of clinical endocrinology and metabolism》2008,93(1):285-292
OBJECTIVE: Intrauterine growth restriction (IUGR) is characterized by decreased placental perfusion. Low oxygen has been shown to increase soluble fms-like tyrosine kinase 1 (sFlt-1) expression in the human placenta. The objective of this study was to examine sFlt-1 expression in different types of IUGR pregnancies, including early-onset severe cases characterized by abnormal umbilical and uterine artery Doppler and discordant IUGR twins in which the normal cotwin represents the optimal control because both placentas share the same uterine environment. PATIENTS: Placentas from four subgroups were collected: early severe IUGR with umbilical artery absent end diastolic flow (n = 19), small for gestational age with normal uterine and umbilical artery Doppler (n = 11), severely growth-restricted dichorionic and monochorionic twins with abnormal umbilical artery Doppler (n = 9), preeclamptic twins (n = 3), and age-matched normal singletons (n = 19) and twin controls (n = 8). RESULTS: Expression of sFlt-1 mRNA and protein was significantly increased in IUGR placentas compared with small for gestational age and normal control placentas. sFlt-1 expression levels were also significantly greater in the small IUGR twin placentas from discordant twin pregnancies compared with the normal cotwin. In preeclamptic twins, sFlt-1 expression was increased in only one of the two placentas. CONCLUSIONS: Our results demonstrate that sFlt-1 expression is increased in severe IUGR placentas with abnormal umbilical artery Doppler of singletons and also in discordant IUGR twins. Reduced placental perfusion may contribute to the increased expression of sFlt-1 in IUGR pregnancies. Our data are compatible with differential sFlt-1 expression in placentas from discordant twins. 相似文献
48.
49.
50.
Kim Fejgin Jacob Nielsen Michelle R. Birknow Jesper F. Bastlund Vibeke Nielsen Jes B. Lauridsen Hreinn Stefansson Stacy Steinberg Helge B.D. Sorensen Troels E. Mortensen Peter H. Larsen Ib V. Klewe Søren V. Rasmussen Kari Stefansson Thomas M. Werge Pekka Kallunki Kenneth V. Christensen Michael Didriksen 《Neuropsychopharmacology》2014