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   1116377篇
  免费   75573篇
  国内免费   4372篇
耳鼻咽喉   15357篇
儿科学   35215篇
妇产科学   29173篇
基础医学   158413篇
口腔科学   30238篇
临床医学   100542篇
内科学   210418篇
皮肤病学   24801篇
神经病学   83999篇
特种医学   44274篇
外国民族医学   218篇
外科学   167605篇
综合类   28373篇
现状与发展   6篇
一般理论   269篇
预防医学   77153篇
眼科学   25700篇
药学   90342篇
  38篇
中国医学   4650篇
肿瘤学   69538篇
  2021年   9668篇
  2019年   9249篇
  2018年   12826篇
  2017年   10232篇
  2016年   11334篇
  2015年   13128篇
  2014年   17568篇
  2013年   24258篇
  2012年   33593篇
  2011年   35577篇
  2010年   20931篇
  2009年   19425篇
  2008年   32135篇
  2007年   34261篇
  2006年   34796篇
  2005年   33141篇
  2004年   31115篇
  2003年   29933篇
  2002年   28692篇
  2001年   60938篇
  2000年   62452篇
  1999年   52035篇
  1998年   13067篇
  1997年   11693篇
  1996年   11522篇
  1995年   10776篇
  1994年   9741篇
  1993年   9134篇
  1992年   38114篇
  1991年   36565篇
  1990年   35987篇
  1989年   34494篇
  1988年   31059篇
  1987年   30152篇
  1986年   28357篇
  1985年   26552篇
  1984年   19245篇
  1983年   16180篇
  1982年   8860篇
  1979年   17059篇
  1978年   11417篇
  1977年   10243篇
  1976年   8845篇
  1975年   10076篇
  1974年   11666篇
  1973年   11287篇
  1972年   10760篇
  1971年   10097篇
  1970年   9253篇
  1969年   8943篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
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   
96.
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   
97.
98.
99.
Inbred mouse strains are the most widely used mammalian model organism in biomedical research owing to ease of genetic manipulation and short lifespan; however, each inbred strain possesses a unique repertoire of deleterious homozygous alleles that can make a specific strain more susceptible to a particular disease. In the current study, we report dystrophic cardiac calcinosis (DCC) in C.B‐17 SCID male mice at 10 weeks of age with no significant change in cardiac function. Acquisition of DCC was characterized by myocardial injury, fibrosis, calcification, and necrosis of the tissue. At 10 weeks of age, 38% of the C.B‐17 SCID mice from two different commercial colonies exhibited significant calcinosis on the ventricular epicardium, predominantly on the right ventricle. The frequency of calcinosis was more than 50% for mice obtained from Taconic's Cambridge City colony and 25% for mice obtained from Taconic's German Town colony. Interestingly, the DCC phenotype did not affect cardiac function at 10 weeks of age. No differences in echocardiography or electrocardiography were observed between the calcinotic and non‐calcinotic mice from either colony. Our findings suggest that C.B‐17 SCID mice exhibit DCC as early as 10 weeks of age with no significant impact on cardiac function. This strain of mice should be cautiously considered for the study of cardiac physiology.  相似文献   
100.
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