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   2042篇
  免费   125篇
  国内免费   83篇
耳鼻咽喉   79篇
儿科学   64篇
妇产科学   25篇
基础医学   154篇
口腔科学   56篇
临床医学   161篇
内科学   420篇
皮肤病学   89篇
神经病学   63篇
特种医学   167篇
外科学   431篇
综合类   122篇
一般理论   1篇
预防医学   83篇
眼科学   50篇
药学   133篇
中国医学   2篇
肿瘤学   150篇
  2023年   13篇
  2022年   13篇
  2021年   69篇
  2020年   37篇
  2019年   50篇
  2018年   71篇
  2017年   43篇
  2016年   37篇
  2015年   45篇
  2014年   47篇
  2013年   70篇
  2012年   119篇
  2011年   104篇
  2010年   81篇
  2009年   71篇
  2008年   96篇
  2007年   134篇
  2006年   110篇
  2005年   99篇
  2004年   103篇
  2003年   84篇
  2002年   60篇
  2001年   63篇
  2000年   70篇
  1999年   50篇
  1998年   35篇
  1997年   36篇
  1996年   42篇
  1995年   31篇
  1994年   21篇
  1993年   24篇
  1992年   21篇
  1991年   28篇
  1990年   17篇
  1989年   31篇
  1988年   21篇
  1987年   28篇
  1986年   17篇
  1985年   20篇
  1984年   6篇
  1983年   14篇
  1982年   11篇
  1981年   15篇
  1980年   15篇
  1979年   9篇
  1978年   11篇
  1977年   10篇
  1976年   13篇
  1975年   11篇
  1957年   3篇
排序方式: 共有2250条查询结果,搜索用时 15 毫秒
61.
62.
63.
The present study investigated haematological alterations induced by oral subacute exposure to fenvalerate, nitrate and their combination in the domestic buffalo, Bubalus bubalis. Fenvalerate exposure produced significant declines in haemoglobin (Hb), total leukocyte count (TLC), total erythrocyte count (TEC) and mean corpuscular haemoglobin concentration (MCHC), and a corresponding elevation in mean corpuscular volume (MCV). Following oral exposure to sodium nitrate, significant declines in blood Hb, TLC, TEC, MCH and MCHC, and a significant elevation in MCV occurred. Combined exposure to fenvalerate and sodium nitrate produced severe effects with an appreciably more prominent decline in Hb, TLC, TEC and MCHC and a significant elevation in MCV. The percentage of methaemoglobin was observed to follow an elevating trend in animals exposed to sodium nitrate alone (0.69 %–13.8 %) and in combination with fenvalerate (0.75 %–13.7 %).  相似文献   
64.
A reply     
  相似文献   
65.
66.
In this study, we hypothesized that higher level of education might be associated with reduced racial disparities in renal transplantation outcomes. We used data from the United States Renal Data System (September 1, 1990–September 1, 2007) (n = 79 223) and analyzed two outcomes, graft loss and recipient mortality, using Cox models. Compared with whites, African Americans had increased risk of graft failure (HR, 1.48; p < 0.001) and recipient mortality (HR, 1.06; p = 0.004). Compared with recipients who graduated from college, all other education groups had inferior graft survival. Specifically, compared with college‐graduated individuals, African Americans who never finished high school had the highest risk of graft failure (HR, 1.45; p < 0.001), followed by high school graduates (HR, 1.27; p < 0.001) and those with some college education (HR, 1.18; p < 0.001). A similar trend was observed in whites. In African Americans (compared with whites), the highest risk of graft failure was associated with individuals who did not complete high school (HR, 1.96; p < 0.001) followed by high school graduates (HR, 1.47; p < 0.001), individuals with some college education (HR, 1.45; p < 0.001), and college graduates (HR, 1.39; p < 0.001). A similar trend was observed with recipient mortality. In sum, higher education was associated with reduced racial disparities in graft and recipient survival.  相似文献   
67.
Shape-specific, macroporous tissue engineering scaffolds were fabricated and homogeneously seeded with cells in a single step. This method brings together CO2 polymer processing and microparticle-based scaffolds in a manner that allows each to solve the key limitation of the other. Specifically, microparticle-based scaffolds have suffered from the limitation that conventional microsphere sintering methods (e.g., heat, solvents) are not cytocompatible, yet we have shown that cell viability was sustained with subcritical (i.e., gaseous) CO2 sintering of microspheres in the presence of cells at near-ambient temperatures. On the other hand, the fused microspheres provided the pore interconnectivity that has eluded supercritical CO2 foaming approaches. Here, fused poly(lactide-co-glycolide) microsphere scaffolds were seeded with human umbilical cord mesenchymal stromal cells to demonstrate the feasibility of utilizing these matrices for cartilage regeneration. We also demonstrated that the approach may be modified to produce thin cell-loaded patches as a promising alternative for skin tissue engineering applications.  相似文献   
68.
Gilbert  HS; Praloran  V; Stanley  ER 《Blood》1989,74(4):1231-1234
Myeloproliferative disease (MPD) is heterogeneous in phenotypic expression and may display features consistent with expansion and activation of the monocyte/macrophage population during its course. The role of colony-stimulating factor-1 (CSF-1) in the pathophysiology of MPD was investigated by measuring circulating CSF-1 levels and examining their relationship to disease phenotype. Serum CSF-1 concentrations, measured by radioimmunoassay, were elevated in all MPD phenotypes. CSF-1 levels differed significantly between groups of patients with essential thrombocythemia, polycythemia vera, and postpolycythemic or agnogenic myeloid metaplasia (in ascending order). CSF-1 serum levels were positively correlated with spleen size and the degree of peripheral bone marrow extension, determined by scintigraphy using a macrophage-seeking isotope. There was no correlation between CSF-1 concentration and circulating levels of erythrocytes, neutrophils or platelets, or the presence of bone marrow fibrosis. Elevated serum CSF-1 levels appear to be associated with an expanded monocyte/macrophage population in MPD. In view of the known cooperativity between CSF-1 and other growth factors in regulating hematopoiesis, the finding of increased serum CSF-1 concentrations and its association with myeloid metaplasia and bone marrow extension may indicate a pathophysiologic role for CSF-1 in determining the phenotypic expression of MPD.  相似文献   
69.
70.
As a nation we are getting older and not all individuals will be fortunate enough to age as successfully as Jean Calment. Improving governmental policies and improving dissemination of information regarding aging to the lay public and health care professionals can make a difference though in how many older individuals can achieve old age with less disability. Teamwork among the patient, health care professionals, and society as a whole can help burnish the "golden years."  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