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   1076451篇
  免费   71675篇
  国内免费   1361篇
耳鼻咽喉   15088篇
儿科学   34626篇
妇产科学   28663篇
基础医学   153571篇
口腔科学   29574篇
临床医学   95071篇
内科学   203961篇
皮肤病学   24397篇
神经病学   81595篇
特种医学   43010篇
外国民族医学   201篇
外科学   163209篇
综合类   21709篇
现状与发展   1篇
一般理论   263篇
预防医学   74734篇
眼科学   24539篇
药学   86214篇
  7篇
中国医学   2805篇
肿瘤学   66249篇
  2019年   7785篇
  2018年   11316篇
  2017年   8930篇
  2016年   10117篇
  2015年   11285篇
  2014年   15323篇
  2013年   22245篇
  2012年   30621篇
  2011年   32370篇
  2010年   19005篇
  2009年   17852篇
  2008年   30025篇
  2007年   32145篇
  2006年   32774篇
  2005年   31096篇
  2004年   29783篇
  2003年   28593篇
  2002年   27571篇
  2001年   60066篇
  2000年   61519篇
  1999年   50969篇
  1998年   12466篇
  1997年   11013篇
  1996年   11026篇
  1995年   10344篇
  1994年   9353篇
  1993年   8864篇
  1992年   37824篇
  1991年   36305篇
  1990年   35772篇
  1989年   34307篇
  1988年   30895篇
  1987年   30010篇
  1986年   28230篇
  1985年   26468篇
  1984年   19211篇
  1983年   16131篇
  1982年   8839篇
  1979年   17043篇
  1978年   11414篇
  1977年   10240篇
  1976年   8845篇
  1975年   10079篇
  1974年   11664篇
  1973年   11281篇
  1972年   10768篇
  1971年   10101篇
  1970年   9259篇
  1969年   8941篇
  1968年   7922篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
The Impella 5.0, a percutaneously inserted left ventricular assist device, has been used to support patients who have severe heart failure or who are undergoing high-risk percutaneous coronary intervention. We report our surgical placement of the Impella 5.0, through a graft sewn to the aorta, to unload the left ventricle of a 59-year-old man who was undergoing venoarterial extracorporeal membrane oxygenation for postcardiotomy shock. The patient underwent successful placement of a long-term left ventricular assist device before his discharge from the hospital. The versatility of the Impella 5.0 is exemplified in this patient who was successfully bridged to long-term support.  相似文献   
72.
73.
74.
75.
76.
77.
ABSTRACT

Objectives: The present study investigated the relationships of enculturation and depressive symptoms with health risk behavior engagement in Mexican-American college students and examined how these relationships differed by gender. Previous research has noted consistent gender differences in health risk behavior (e.g. alcohol use, substance use, and risky sexual behavior) among Latina/os, and emphasized the role of U.S. acculturation in this difference. Research examining the role of heritage cultural retention (i.e. enculturation), and including the added influence of mental health variables, such as depressive symptoms, is currently lacking. This study sought to address this gap.

Design: A large sample (N?=?677) of Mexican-American college students from four universities (located in New York, California, Florida, and Texas) completed an online questionnaire assessing health risk behaviors and corresponding variables.

Results: We found that males who endorsed more behavioral enculturation and depressive symptoms were more likely to engage in health risk behavior than all others in the sample. Contrary to previous literature, no relationship was found between behavioral enculturation and health risk behavior in females.

Conclusion: The current study found behavioral enculturation to be associated with depressive symptoms, and in turn with health risk behaviors among the males in our sample. Additional research will be needed to identify the mechanism underlying the relationship between enculturation and depressive symptoms as well as between depressive symptoms and risky behavior.  相似文献   
78.
Platelet α-granules release growth factors (GFs) that promote healing and tissue regeneration. Platelet-rich plasma (PRP) is shown to be beneficial in treating alopecia, and however, clinical response can be inconsistent. Due to several fold enrichment of platelets secreting large quantities of GFs following PRP injections, heterogeneity in amounts of GFs secreted by platelets may contribute to inconsistent clinical responses. Herein, we evaluated factors that could potentially contribute to heterogeneous secretion of GFs by platelets. We measured platelet secretion of transforming growth factor beta1 (TGFβ1), platelet-derived growth factor (PDGF-BB), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF2) in aliquots of de-identified PRP samples from female patients undergoing therapy in the hair disease clinic. Although secretion of GFs by platelets was comparable in PRP samples of patients with non-cicatricial and cicatricial alopecia, a Shapiro-Wilk test for normal distribution indicated significant variability across all patient samples. The amount of GF secreted by platelets was comparable when PRP prepared from two FDA-cleared devices with distinct techniques were compared. We provide evidence of platelets secreting heterogeneous amounts of GFs within each sample as high and low secretion of random factors could be simultaneously detected. These results suggest inherent heterogeneity in secretion of GFs by platelets in patient samples that are not influenced by the device used to prepare PRP. Since some GFs could have antagonistic effects on hair growth, a balance between amounts of growth promoting and inhibiting factors may be crucial in determining clinical response to PRP therapy.  相似文献   
79.
80.
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