全文获取类型
收费全文 | 1176172篇 |
免费 | 79111篇 |
国内免费 | 3034篇 |
专业分类
耳鼻咽喉 | 15403篇 |
儿科学 | 41107篇 |
妇产科学 | 33667篇 |
基础医学 | 168927篇 |
口腔科学 | 32767篇 |
临床医学 | 104787篇 |
内科学 | 225129篇 |
皮肤病学 | 26826篇 |
神经病学 | 89957篇 |
特种医学 | 48310篇 |
外国民族医学 | 385篇 |
外科学 | 176705篇 |
综合类 | 25025篇 |
一般理论 | 405篇 |
预防医学 | 93070篇 |
眼科学 | 26469篇 |
药学 | 84321篇 |
6篇 | |
中国医学 | 2171篇 |
肿瘤学 | 62880篇 |
出版年
2018年 | 14244篇 |
2017年 | 12361篇 |
2016年 | 12631篇 |
2015年 | 15258篇 |
2014年 | 18442篇 |
2013年 | 25291篇 |
2012年 | 38386篇 |
2011年 | 35475篇 |
2010年 | 20675篇 |
2009年 | 21111篇 |
2008年 | 30975篇 |
2007年 | 33266篇 |
2006年 | 34012篇 |
2005年 | 41290篇 |
2004年 | 43476篇 |
2003年 | 37397篇 |
2002年 | 30184篇 |
2001年 | 50470篇 |
2000年 | 49611篇 |
1999年 | 44861篇 |
1998年 | 11744篇 |
1997年 | 10386篇 |
1996年 | 10541篇 |
1995年 | 10155篇 |
1994年 | 9428篇 |
1992年 | 37673篇 |
1991年 | 37105篇 |
1990年 | 36778篇 |
1989年 | 35385篇 |
1988年 | 32361篇 |
1987年 | 32315篇 |
1986年 | 30234篇 |
1985年 | 28800篇 |
1984年 | 21343篇 |
1983年 | 17912篇 |
1982年 | 10145篇 |
1981年 | 9051篇 |
1979年 | 20065篇 |
1978年 | 14157篇 |
1977年 | 11840篇 |
1976年 | 11060篇 |
1975年 | 12256篇 |
1974年 | 14965篇 |
1973年 | 14162篇 |
1972年 | 13245篇 |
1971年 | 12474篇 |
1970年 | 11550篇 |
1969年 | 10819篇 |
1968年 | 10014篇 |
1967年 | 9066篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
153.
C F A Peralta P Cavoretto B Csapo O Falcon K H Nicolaides 《Ultrasound in obstetrics & gynecology》2006,27(2):128-133
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined. 相似文献
154.
B Sedgmen C McMahon D Cairns R J Benzie R L Woodfield 《Ultrasound in obstetrics & gynecology》2006,27(3):245-251
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure. 相似文献
155.
A. Cagnin M. Kassiou S. R. Meikle R. B. Banati 《Acta neurologica Scandinavica》2006,114(S185):107-114
156.
M Müller J Grunewald C Olgart H?glund B Dahlén A Eklund H Stridh 《The European respiratory journal》2006,28(3):513-522
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation. 相似文献
157.
Pancreatic Panniculitis Associated with Allograft Pancreatitis and Rejection in a Simultaneous Pancreas–Kidney Transplant Recipient 总被引:1,自引:0,他引:1
J. L. Pike J. C. Rice R. L. Sanchez E. B. Kelly B. C. Kelly 《American journal of transplantation》2006,6(10):2502-2505
Pancreatic panniculitis is an uncommon condition that can occur in association with pancreatic disease. We present a case of pancreatic panniculitis in a female pancreas-kidney transplant recipient 5 months post-transplant. The patient was on standard immunosuppressive medications and had acute rejection of her renal allograft. The diagnosis of allograft pancreatitis and rejection presenting with pancreatic panniculitis was supported clinically, histopathologically and by laboratory and imaging data. This is the fourth case of pancreatic panniculitis occurring in a transplant recipient and the first in a simultaneous pancreas-kidney transplant recipient. It is also the first case associated with allograft rejection. Clinicians should be aware that pancreatic panniculitis may be a manifestation of underlying allograft pancreatic disease. 相似文献
158.
Sergue? O Fetissov Jarmila Hallman Ida Nilsson Ann-Kari Lefvert Lars Oreland Tomas H?kfelt 《Neuropsychopharmacology》2006,60(8):799-802
BACKGROUND: Altered stress response is characteristic for subjects with abnormal aggressive and antisocial behavior, but the underlying biological mechanisms are unclear. We hypothesized that autoantibodies (autoAbs) directed against several stress-related neurohormones may exist in aggressive subjects. METHODS: Using enzyme-linked immunosorbent assay, we studied whether autoAbs directed against corticotropin (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), oxytocin, and vasopressin are present in serum of male subjects with conduct disorder and prisoners with history of violence. Healthy blood donors served as control subjects. RESULTS: Both conduct disorder and prisoners groups displayed strongly increased levels of ACTH-reactive immunoglobulin G (IgG) and immunoglobulin M (IgM) autoAbs compared with control subjects. Levels of oxytocin-reactive IgM autoAbs were slightly increased in both groups of aggressive subjects, whereas levels of vasopressin-reactive IgG and IgM autoAbs were lower only in conduct disorder. No differences in the levels of alpha-MSH-reactive autoAbs were found between aggressive and control subjects. CONCLUSIONS: High levels of ACTH-reactive autoAbs as well as altered levels of oxytocin- and vasopressin-reactive autoAbs found in aggressive subjects may interfere with the neuroendocrine mechanisms of stress and motivated behavior. Our data suggest a new biological mechanism of human aggressive behavior that involves autoAbs directed against several stress-related neurohormones. 相似文献
159.
160.
Stephen J Glatt Erik G J?nsson 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2006,(2):149-154
Previously we derived independent estimates of the effect of the dopamine D2 receptor (DRD2) Ser311Cys polymorphism on risk for schizophrenia using fixed- and random-effects meta-analyses. Both analyses identified a significant association between the Cys allele and schizophrenia, but neither included all available data. Furthermore, genotype data were not evaluated in either analysis, thus precluding any determination of the mode of inheritance. The present study was conducted to resolve discrepancies between the existing meta-analyses, and provide more comprehensive and accurate estimates of the nature and magnitude of the influence of the Ser311Cys polymorphism on risk for schizophrenia. All discrepancies between the two sets of previously meta-analyzed studies were identified and resolved to the mutual satisfaction of the authors, and the final dataset was analyzed independently by fixed- and random-effects meta-analyses. A total of 27 samples, comprising 3,707 schizophrenia patients and 5,363 control subjects, were included in the analyses of allelic association, while smaller numbers of studies and subjects were included in each of the genotypic association analyses. A significant effect of the Cys allele was observed under both fixed-effects (odds ratio [OR] = 1.4; P = 0.002) and random-effects (OR = 1.4; P = 0.007) models. Cys/Ser heterozygotes were at elevated risk for schizophrenia when compared to Ser/Ser homozygotes (fixed- and random-effects OR = 1.4, p(s) or= 0.948). There was no evidence of heterogeneity, excessive influence of any single study, or publication bias in any of the analyses, suggesting that the effect of this DRD2 polymorphism on schizophrenia risk is reliable and uniform across populations, and our estimates of its magnitude are robust and accurate. 相似文献