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   1365690篇
  免费   114761篇
  国内免费   6459篇
耳鼻咽喉   17133篇
儿科学   43660篇
妇产科学   37043篇
基础医学   186965篇
口腔科学   36921篇
临床医学   123352篇
内科学   284445篇
皮肤病学   32150篇
神经病学   112943篇
特种医学   56426篇
外国民族医学   274篇
外科学   214942篇
综合类   32140篇
现状与发展   2篇
一般理论   437篇
预防医学   108884篇
眼科学   28760篇
药学   95571篇
  5篇
中国医学   2286篇
肿瘤学   72571篇
  2018年   13914篇
  2017年   11082篇
  2016年   13224篇
  2015年   14797篇
  2014年   20793篇
  2013年   30964篇
  2012年   37981篇
  2011年   40706篇
  2010年   25375篇
  2009年   24840篇
  2008年   38045篇
  2007年   40553篇
  2006年   41811篇
  2005年   40359篇
  2004年   38481篇
  2003年   37602篇
  2002年   35505篇
  2001年   66337篇
  2000年   68211篇
  1999年   56921篇
  1998年   17142篇
  1997年   15310篇
  1996年   16313篇
  1995年   16457篇
  1994年   15309篇
  1993年   14343篇
  1992年   47321篇
  1991年   45934篇
  1990年   44152篇
  1989年   41980篇
  1988年   38924篇
  1987年   38220篇
  1986年   35994篇
  1985年   34772篇
  1984年   26517篇
  1983年   22256篇
  1982年   14014篇
  1981年   12614篇
  1980年   11839篇
  1979年   23649篇
  1978年   17176篇
  1977年   14485篇
  1976年   13259篇
  1975年   13792篇
  1974年   16177篇
  1973年   15479篇
  1972年   14254篇
  1971年   13097篇
  1970年   11932篇
  1969年   11154篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
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   
32.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  相似文献   
33.
34.
Imaging     
  相似文献   
35.
36.
37.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
38.
39.
40.
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