首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2012篇
  免费   131篇
  国内免费   14篇
耳鼻咽喉   8篇
儿科学   74篇
妇产科学   31篇
基础医学   225篇
口腔科学   54篇
临床医学   162篇
内科学   389篇
皮肤病学   33篇
神经病学   169篇
特种医学   160篇
外国民族医学   1篇
外科学   376篇
综合类   45篇
一般理论   5篇
预防医学   130篇
眼科学   33篇
药学   147篇
中国医学   4篇
肿瘤学   111篇
  2023年   11篇
  2022年   21篇
  2021年   75篇
  2020年   35篇
  2019年   52篇
  2018年   51篇
  2017年   42篇
  2016年   60篇
  2015年   40篇
  2014年   77篇
  2013年   100篇
  2012年   111篇
  2011年   95篇
  2010年   93篇
  2009年   65篇
  2008年   101篇
  2007年   98篇
  2006年   92篇
  2005年   92篇
  2004年   75篇
  2003年   66篇
  2002年   46篇
  2001年   34篇
  2000年   44篇
  1999年   63篇
  1998年   44篇
  1997年   32篇
  1996年   32篇
  1995年   20篇
  1994年   29篇
  1993年   29篇
  1992年   21篇
  1991年   21篇
  1990年   12篇
  1989年   22篇
  1988年   23篇
  1987年   16篇
  1986年   23篇
  1985年   20篇
  1984年   14篇
  1983年   14篇
  1982年   12篇
  1981年   14篇
  1980年   15篇
  1977年   9篇
  1976年   12篇
  1974年   13篇
  1973年   9篇
  1972年   8篇
  1971年   9篇
排序方式: 共有2157条查询结果,搜索用时 15 毫秒
91.
Laparoscopic liver surgery is now an established practice in many institutions. It is a safe and feasible approach in the hands of trained surgeons. The introduction of robotics into surgery represents progression in the field of minimally invasive surgery but has seen a slow uptake in the hepatopancreaticobiliary subspeciality. We report our initial experience in 20 cases of laparoscopic robotic liver resection (LRLR). From March 2011 to April 2013 patients with lesions within the liver were assessed and consented for laparoscopic robotic liver surgery. This is a retrospective analysis of a prospectively kept database on preoperative details and intraoperative and postoperative outcomes. During the time period there were 20 LRLRs. The median age was 62 years (range 39–80 years) with a male to female ratio of 14:6. Ten patients had left lateral sectionectomies, 10 patients had atypical segmental resections; 14 patients had resections for malignancies, 6 patients had resections for benign disease. One case was converted to open resection. The mean operating time was 176.4 ± 74.6 min (range 60–300 min), the mean blood loss was 107 ± 106 ml (range 50–700 ml) and the mean hospital stay was 6.5 ± 3.7 days (range 2–16 days). Two patients required blood transfusions. The incidence of postoperative complications was 10 % (n = 2). LRLR overcomes some of the disadvantages of conventional laparoscopic surgery. It is a technically feasible and safe approach for wedge resections and left lateral sectionectomy of the liver without oncological compromise. However, this surgical technique requires advanced laparoscopic skills and there is an associated steep learning curve. Further studies are needed to determine the potential advantages of this technique for the patient compared to the traditional laparoscopic approach.  相似文献   
92.
Early life stress (ELS) is known to have considerable influence on brain development and affective functioning. Previous studies in clinical populations have shown that hippocampus and amygdala, two central structures of limbic emotion processing circuits, are predominantly affected by early stress exposure. Given the inconsistent findings on ELS‐related effects in healthy populations and the associations of ELS and affective functioning, the question arises which additional emotion‐relevant variables need to be considered to better understand the effects of ELS. We, therefore, investigated the volume of hippocampus and amygdala in 25 high alexithymic (h‐ALEX) and 25 low alexithymic (l‐ALEX) individuals, which were matched with regard to ELS, but significantly differed in their degree of emotional functioning. Volumetric analyses were performed using FSL‐FIRST, a method to automatically segment subcortical structures on T1‐weighted magnetic resonance images. Alexithymia was assessed using the Toronto Alexithymia Scale and Bermond–Vorst Alexithymia Questionnaire. ELS was assessed by Childhood Trauma Questionnaire (CTQ) and Early Trauma Inventory. Our data showed that ELS was negatively associated with right hippocampus volume in h‐ALEX individuals, while there was no such association in the l‐ALEX group. Furthermore, ELS was positively associated with left amygdala volume in l‐ALEX individuals, but not in individuals with high levels of alexithymia. The present study emphasizes a substantial relationship between intrapersonal factors, such as alexithymia and neural alterations related to the experience of ELS. Longitudinal study designs are necessary to pursue the question of how emotional abilities interact with individual adaptations to early stress exposure on the neural level. © 2014 Wiley Periodicals, Inc.  相似文献   
93.
94.
95.
Purpose: This study aimed to determine the real-world prognostic significance of lymph node ratio (LNR) and log odds of positive lymph nodes (LOPLN) in patients with non-metastatic small bowel adenocarcinoma. Methods: Patients diagnosed with early-stage small bowel adenocarcinoma between January 2007 and December 2018 from a large Canadian province were identified. We calculated the LNR by dividing positive over total lymph nodes examined and the LOPLN as log ([positive lymph nodes + 0.5]/[negative lymph nodes + 0.5]). The LNR and LOPLN were categorized at cut-offs of 0.4 and −1.1, respectively. Multivariable Cox proportional hazards models were constructed for each nodal stage, LNR and LOPLN, adjusting for measured confounding factors. Harrell’s C-index and Akaike’s Information Criterion (AIC) were used to calculate the prognostic discriminatory abilities of the different models. Results: We identified 141 patients. The median age was 67 years and 54.6% were men. The 5-year overall survival rates for patients with stage I, II and III small bowel adenocarcinoma were 50.0%, 56.6% and 47.5%, respectively. The discriminatory ability was generally comparable for LOPLN, LNR and nodal stage in the prognostication of all patients. However, LOPLN had higher discriminatory ability among patients with at least one lymph node involvement (Harrell’s C-index, 0.75, 0.77 and 0.82, and AIC, 122.91, 119.68 and 110.69 for nodal stage, LNR and LOPLN, respectively). Conclusion: The LOPLN may provide better prognostic information when compared to LNR and nodal stage in specific patients.  相似文献   
96.
97.
98.
目的数值模拟抗血管生成因子Angiostatin和Endostatin对肿瘤血管生成的影响。方法建立肿瘤内外血管生成的二维离散数学模型。模型耦合两种抗血管生成因子Angiostatin和Endostatin的抑制效应,数值模拟在促血管生成因子诱导下肿瘤微血管网生成,讨论血管生成抑制因子的影响。结果抗血管生成因子Angiostatin对肿瘤内外血管网络生成的速度和成熟度有抑制作用。抗血管生成因子Angiostatin和Endostatin耦合作用时,在肿瘤血管生成的早期有明显的抑制效应;在肿瘤血管生成的中后期,它们可以降低肿瘤血管化程度。结论本文模型能够较好的模拟抗血管生成因子Angiostatin和Endostatin对内皮细胞迁移和增殖的抑制作用。  相似文献   
99.
Hemodynamic shear stress and its role in atherosclerosis   总被引:59,自引:0,他引:59  
Malek AM  Alper SL  Izumo S 《JAMA》1999,282(21):2035-2042
Atherosclerosis, the leading cause of death in the developed world and nearly the leading cause in the developing world, is associated with systemic risk factors including hypertension, smoking, hyperlipidemia, and diabetes mellitus, among others. Nonetheless, atherosclerosis remains a geometrically focal disease, preferentially affecting the outer edges of vessel bifurcations. In these predisposed areas, hemodynamic shear stress, the frictional force acting on the endothelial cell surface as a result of blood flow, is weaker than in protected regions. Studies have identified hemodynamic shear stress as an important determinant of endothelial function and phenotype. Arterial-level shear stress (>15 dyne/cm2) induces endothelial quiescence and an atheroprotective gene expression profile, while low shear stress (<4 dyne/cm2), which is prevalent at atherosclerosis-prone sites, stimulates an atherogenic phenotype. The functional regulation of the endothelium by local hemodynamic shear stress provides a model for understanding the focal propensity of atherosclerosis in the setting of systemic factors and may help guide future therapeutic strategies.  相似文献   
100.
The aim of this study was to investigate the effect of pre-irradiation with microwaves on the induction of radioadaptive response. In the 1st phase of the study, 110 male mice were divided into 8 groups. The animals in these groups were exposed/sham-exposed to microwave, low dose rate gamma or both for 5 days. On day six, the animals were exposed to a lethal dose (LD). In the 2nd phase, 30 male rats were divided into 2 groups of 15 animals. The 1st group received microwave exposure. The 2nd group (controls) received the same LD but there was no treatment before the LD. On day 5, all animals were whole-body irradiated with the LD. Statistically significant differences between the survival rate of the mice only exposed to lethal dose of gamma radiation before irradiation with a lethal dose of gamma radiation with those of the animals pre-exposed to either microwave (p=0.02), low dose rate gamma (p=0.001) or both of these physical adapting doses (p=0.003) were observed. Likewise, a statistically significant difference between survival rates of the rats in control and test groups was observed. Altogether, these experiments showed that exposure to microwave radiation may induce a significant survival adaptive response.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号