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   3287249篇
  免费   232444篇
  国内免费   5797篇
耳鼻咽喉   47152篇
儿科学   104257篇
妇产科学   90941篇
基础医学   477768篇
口腔科学   93611篇
临床医学   292503篇
内科学   632061篇
皮肤病学   73549篇
神经病学   259712篇
特种医学   125214篇
外国民族医学   894篇
外科学   499343篇
综合类   71142篇
现状与发展   16篇
一般理论   1189篇
预防医学   248310篇
眼科学   78061篇
药学   246137篇
  15篇
中国医学   6806篇
肿瘤学   176809篇
  2018年   34494篇
  2017年   26358篇
  2016年   29484篇
  2015年   33133篇
  2014年   46749篇
  2013年   70820篇
  2012年   96109篇
  2011年   102260篇
  2010年   60932篇
  2009年   57946篇
  2008年   96755篇
  2007年   104034篇
  2006年   104874篇
  2005年   101907篇
  2004年   97912篇
  2003年   94646篇
  2002年   92081篇
  2001年   148903篇
  2000年   152790篇
  1999年   129001篇
  1998年   37136篇
  1997年   32790篇
  1996年   32450篇
  1995年   30775篇
  1994年   28470篇
  1993年   26828篇
  1992年   100507篇
  1991年   98088篇
  1990年   95954篇
  1989年   92904篇
  1988年   85921篇
  1987年   84504篇
  1986年   79858篇
  1985年   76596篇
  1984年   57040篇
  1983年   48635篇
  1982年   29102篇
  1981年   26252篇
  1979年   53442篇
  1978年   38300篇
  1977年   32491篇
  1976年   30466篇
  1975年   33620篇
  1974年   40138篇
  1973年   38531篇
  1972年   36487篇
  1971年   34434篇
  1970年   32152篇
  1969年   30728篇
  1968年   28418篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Sniff nasal inspiratory pressure (SNIP) measurement is a volitional noninvasive assessment of inspiratory muscle strength. A maximum of 10 sniffs is generally used. The purpose of the present study was to investigate whether the maximum SNIP improved after the tenth sniff. In total, 20 healthy volunteers and 305 patients with various neuromuscular and lung diseases were encouraged to perform 40 and 20 sniffs, respectively. The best SNIP among the first 10 sniffs was lower than the best SNIP among the next 10 sniffs in the healthy volunteers and patients. The SNIP improvement after the twentieth sniff was marginal. In conclusion, a learning effect persists after the tenth sniff. The current authors suggest using 10 additional sniffs when the best result of the first 10 sniffs is slightly below normal, or when sniff nasal inspiratory pressure is used to monitor a progressive decline in inspiratory muscle strength.  相似文献   
62.
The precise molecular cause of insulin resistance has not yet been elucidated. Resistance to the normal action of insulin contributes to the pathogenesis of a number of common human disorders, including type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus, hypertension, and the Metabolic Syndrome X, thus constituting a major public health problem. A disease program aimed at combating this disorder should focus on the identification of targets for therapeutic intervention which may overcome insulin resistance and hence the associated metabolic consequences characteristic of the Metabolic Syndrome. Although the primary defect in the pathogenesis of type 2 diabetes is unknown, genetic and environmental factors are likely to contribute to the manifestation of this progressive metabolic disorder, which is usually not clinically apparent until mid-life. Defects at the level of glucose uptake/phosphorylation characterize insulin resistance in skeletal muscle of type 2 diabetic patients. Identification of putative components of the insulin receptor-signaling pathway may offer insights into mechanisms involved in insulin resistance. Enhanced flux of free fatty acids due to impaired lipid metabolism may contribute to impaired insulin secretion and peripheral insulin resistance. Genes regulating lipolysis are prime candidates for susceptibility towards the metabolic syndrome. Here we describe pathways constituting complex interactions that control glucose homeostasis. We will be considering (1) regulation of glucose uptake by the insulin receptor signaling pathway, and (2) control of adipogenesis and insulin sensitivity by the sterol response element binding protein (SREBP) pathway.  相似文献   
63.
64.
65.
66.
67.
68.
69.
70.
BACKGROUND: Three dimensional skin equivalents are widely used in dermatopharmacological and toxicological studies and as autologous transplants in wound healing. In pharmacology, there is tremendous need for monitoring the response of engineered skin equivalents to external treatment. Transplantation of skin equivalents for wound healing requires careful verification of their quality prior to transplantation. Optical coherence tomography (OCT) is a non-contact, non-destructive imaging technique for living tissues offering the potential to fulfill these needs. This work presents an analysis of OCT for high-resolution monitoring of skin equivalents at different stages during the culture process. METHODS: We developed a high-resolution OCT imaging setup based on a commercially available OCT system. A broadband femtosecond laser light source replaces the original superluminescence diode. Tomograms of living skin equivalents were recorded with an axial resolution of 3 mum and correlated with histology and immunofluorescence images. Comparison with standard low-resolution OCT is presented to emphasize the advantages of high-resolution OCT for this application. RESULTS: OCT is particularly able to distinguish between different layers of skin equivalents including stratum corneum, epidermal and dermal layer as well as the basement membrane zone. The high-resolution OCT scans correlate closely with two key benchmarks, histology and immunofluorescence imaging. CONCLUSIONS: This study clearly demonstrates the benefits of high-resolution OCT for identifying living tissue structure and morphology. Compared with the current gold standard histology, OCT offers non-destructive tissue imaging, enabling high-resolution evaluation of living tissue morphology and structure as it evolves.  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