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   1900篇
  免费   128篇
  2023年   14篇
  2022年   19篇
  2021年   52篇
  2020年   22篇
  2019年   34篇
  2018年   48篇
  2017年   28篇
  2016年   52篇
  2015年   99篇
  2014年   102篇
  2013年   144篇
  2012年   162篇
  2011年   135篇
  2010年   78篇
  2009年   61篇
  2008年   75篇
  2007年   88篇
  2006年   81篇
  2005年   77篇
  2004年   74篇
  2003年   75篇
  2002年   59篇
  2001年   33篇
  2000年   27篇
  1999年   22篇
  1998年   12篇
  1996年   11篇
  1995年   14篇
  1994年   12篇
  1993年   15篇
  1992年   12篇
  1991年   19篇
  1990年   14篇
  1989年   15篇
  1988年   22篇
  1987年   26篇
  1986年   17篇
  1985年   18篇
  1984年   15篇
  1982年   10篇
  1981年   9篇
  1980年   8篇
  1979年   12篇
  1978年   14篇
  1977年   7篇
  1976年   10篇
  1975年   13篇
  1973年   6篇
  1972年   6篇
  1971年   6篇
排序方式: 共有2028条查询结果,搜索用时 156 毫秒
61.

Background

Severe acute malnutrition (SAM) is the most serious form of malnutrition affecting children under-five and is associated with many infectious diseases including Tuberculosis (TB). In India, nutritional rehabilitation centres (NRCs) have been recently established for the management of SAM including TB. The National TB Programme (NTP) in India has introduced a revised algorithm for diagnosing paediatric TB. We aimed to examine whether NRCs adhered to these guidelines in diagnosing TB among SAM children.

Methods

A cross-sectional study involving review of records of all SAM children identified by health workers during 2012 in six tehsils (sub-districts) with NRCs (population: 1.8 million) of Karnataka, India.

Results

Of 1927 identified SAM children, 1632 (85%) reached NRCs. Of them, 1173 (72%) were evaluated for TB and 19(2%) were diagnosed as TB. Of 1173, diagnostic algorithm was followed in 460 (37%). Among remaining 763 not evaluated as per algorithm, tuberculin skin test alone was conducted in 307 (41%), chest radiography alone in 99 (13%) and no investigations in 337 (45%). The yield of TB was higher among children evaluated as per algorithm (4%) as compared to those who were not (0.3%) (OR: 15.3 [95%CI: 3.5-66.3]). Several operational challenges including non-availability of a full-time paediatrician, non-functioning X-ray machine due to frequent power cuts, use of tuberculin with suboptimal strength and difficulties in adhering to a complex diagnostic algorithm were observed.

Conclusion

This study showed that TB screening in NRCs was sub-optimal in Karnataka. Some children did not reach the NRC, while many of those who did were either not or sub-optimally evaluated for TB. This study pointed to a number of operational issues that need to be addressed if this collaborative strategy is to identify more TB cases amongst malnourished children in India.  相似文献   
62.
63.
Accurate multidimensional localization of isolated fluorescent emitters is a time consuming process in single-molecule based super-resolution microscopy. We demonstrate a functional method for real-time reconstruction with automatic feedback control, without compromising the localization accuracy. Compatible with high frame rates of EM-CCD cameras, it relies on a wavelet segmentation algorithm, together with a mix of CPU/GPU implementation. A combination with Gaussian fitting allows direct access to 3D localization. Automatic feedback control ensures optimal molecule density throughout the acquisition process. With this method, we significantly improve the efficiency and feasibility of localization-based super-resolution microscopy.  相似文献   
64.
Prostate cancer (PCa) is the most common type of cancer in men in the United States, which disproportionately affects African American descents. While metastasis is the most common cause of death among PCa patients, no specific markers have been assigned to severity and ethnic biasness of the disease. MicroRNAs represent a promising new class of biomarkers owing to their inherent stability and resilience. In the present study, we investigated potential miRNAs that can be used as biomarkers and/or therapeutic targets and can provide insight into the severity and ethnic biasness of PCa. PCR array was performed in FFPE PCa tissues (5 Caucasian American and 5 African American) and selected differentially expressed miRNAs were validated by qRT-PCR, in 40 (15 CA and 25 AA) paired PCa and adjacent normal tissues. Significantly deregulated miRNAs were also analyzed in urine samples to explore their potential as non-invasive biomarker for PCa. Out of 8 miRNAs selected for validation from PCR array data, miR-205 (p<0.0001), mir-214 (p<0.0001), miR-221(p<0.001) and miR-99b (p<0.0001) were significantly downregulated in PCa tissues. ROC curve shows that all four miRNAs successfully discriminated between PCa and adjacent normal tissues. MiR-99b showed significant down regulation (p<0.01) in AA PCa tissues as compared to CA PCa tissues and might be related to the aggressiveness associated with AA population. In urine, miR-205 (p<0.05) and miR-214 (p<0.05) were significantly downregulated in PCa patients and can discriminate PCa patients from healthy individuals with 89% sensitivity and 80% specificity. In conclusion, present study showed that miR-205 and miR-214 are downregulated in PCa and may serve as potential non-invasive molecular biomarker for PCa.  相似文献   
65.
Preclinical studies of animals with risk factors, and how those risk factors contribute to the development of cardiovascular disease and cardiac dysfunction, are clearly needed. One such approach is to feed mice a diet rich in fat (i.e. 60%). Here, we determined whether a high fat diet was sufficient to induce cardiac dysfunction in mice. We subjected mice to two different high fat diets (lard or milk as fat source) and followed them for over six months and found no significant decrement in cardiac function (via echocardiography), despite robust adiposity and impaired glucose disposal. We next determined whether antecedent and concomitant exposure to high fat diet (lard) altered the murine heart’s response to infarct-induced heart failure; high fat feeding during, or before and during, heart failure did not significantly exacerbate cardiac dysfunction. Given the lack of a robust effect on cardiac dysfunction with high fat feeding, we then examined a commonly used mouse model of overt diabetes, hyperglycemia, and obesity (db/db mice). db/db mice (or STZ treated wild-type mice) subjected to pressure overload exhibited no significant exacerbation of cardiac dysfunction; however, ischemia-reperfusion injury significantly depressed cardiac function in db/db mice compared to their non-diabetic littermates. Thus, we were able to document a negative influence of a risk factor in a relevant cardiovascular disease model; however, this did not involve exposure to a high fat diet. High fat diet, obesity, or hyperglycemia does not necessarily induce cardiac dysfunction in mice. Although many investigators use such diabetes/obesity models to understand cardiac defects related to risk factors, this study, along with those from several other groups, serves as a cautionary note regarding the use of murine models of diabetes and obesity in the context of heart failure.  相似文献   
66.
Noncollagenous proteins in the bone extracellular matrix, such as osteocalcin (OC) and osteopontin (OPN), inherent to evolution of bone as a skeletal tissue, are known to regulate bone formation and mineralization. However, the fundamental basis of this regulatory role remains unknown. Here, for the first time, we use mouse mesenchymal stem/stromal cells (MSC) lacking both OC and OPN to investigate the mechanistic roles of OC and OPN on the proliferation capacity and differentiation ability of MSC. We found that the loss of OC and OPN reduces stem cells self-renewal potential and multipotency, affects their differentiation into an osteogenic lineage, and impairs their angiogenic potential while maintaining chondrogenic and adipogenic lineages. Moreover, loss of OC and OPN compromises the extracellular matrix integrity and maturation, observed by an unexpected enhancement of glycosaminoglycans content that are associated with a more primitive skeletal connective tissue, and by a delay on the maturation of mineral species produced. Interestingly, exogenously supplemented OC and OPN were able to rescue MSC proliferative and osteogenic potential along with matrix integrity and mineral quality. Taken together, these results highlight the key contributions of OC and OPN in enhancing osteogenesis and angiogenesis over primitive connective tissue, and support a potential therapeutic approach based on their exogenous supplementation.  相似文献   
67.
68.
Inosine monophosphate dehydrogenase (IMPDH) plays an important role in the Guanosine monophosphate (GMP) biosynthesis pathway. As hIMPDH-II is involved in CML-Cancer, it is thought to be an active target for leukemic drug design. The importance of conserved water molecules in the salt-bridge-mediated interdomain recognition and loop-flap recognition of hIMPDH has already been indicated in some simulation studies (Bairagya et al., 2009, 2011a, 2011b, 2012; Mishra et al., 2012). In this work, the role of conserved water molecules in the recognition of Inosine monophosphate (IMP) and NAD+ (co-factor) to active site residues of both the isoforms has been investigated by all atoms MD-Simulation studies. During 25-ns dynamics of the solvated hIMPDH-II and I (1B3O and 1JCN PDB structures), the involvement of conserved water molecular triad (W M, W L and W C) in the recognition of active site residues (Asp 274, Asn 303, Arg 322, and Asp 364), IMP and NAD+ has been observed (Figure 1). The H-bonding co-ordination of all three conserved water molecular centers is within 4–7 and their occupation frequency is 1.0. The H-bonding geometry and the electronic consequences of the water molecular interaction at the different residues (and also IMP and NAD+) may put forward some rational clues on antileukemic agent design.  相似文献   
69.
70.
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