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   3778篇
  免费   306篇
  国内免费   7篇
耳鼻咽喉   17篇
儿科学   100篇
妇产科学   79篇
基础医学   385篇
口腔科学   40篇
临床医学   527篇
内科学   721篇
皮肤病学   27篇
神经病学   366篇
特种医学   121篇
外科学   327篇
综合类   50篇
一般理论   1篇
预防医学   602篇
眼科学   67篇
药学   353篇
中国医学   2篇
肿瘤学   306篇
  2023年   17篇
  2022年   38篇
  2021年   94篇
  2020年   53篇
  2019年   85篇
  2018年   94篇
  2017年   70篇
  2016年   78篇
  2015年   91篇
  2014年   120篇
  2013年   178篇
  2012年   241篇
  2011年   301篇
  2010年   143篇
  2009年   146篇
  2008年   259篇
  2007年   254篇
  2006年   240篇
  2005年   231篇
  2004年   228篇
  2003年   210篇
  2002年   203篇
  2001年   41篇
  2000年   35篇
  1999年   46篇
  1998年   32篇
  1997年   47篇
  1996年   27篇
  1995年   35篇
  1994年   22篇
  1993年   18篇
  1992年   36篇
  1991年   37篇
  1990年   24篇
  1989年   26篇
  1988年   31篇
  1987年   22篇
  1986年   19篇
  1985年   20篇
  1984年   22篇
  1983年   10篇
  1982年   17篇
  1981年   20篇
  1980年   14篇
  1979年   11篇
  1978年   8篇
  1977年   11篇
  1972年   10篇
  1971年   9篇
  1969年   9篇
排序方式: 共有4091条查询结果,搜索用时 0 毫秒
61.
62.
Serum Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA+-M2BP) is a novel marker for evaluating fibrosis and predicting the development of hepatocellular carcinoma (HCC). However, the role of WFA+-M2BP in the prognosis of HCC patients after curative surgery remains unknown. In this study, we aimed to evaluate the prognostic role of serum WFA+-M2BP in HCC patients after curative resection and liver transplantation. We enrolled 460 HCC patients (357 resection and 103 transplantation) to analyze the risk factors for HCC recurrence and patient’s survival. We employed time-to-event models using univariate and multivariable Cox proportional hazards regression analyses and calculated the hazard ratios (HRs) and adjusted HRs with their corresponding 95% confidence intervals (CIs). The levels of WFA+-M2BP were 0.19-14.51 COI (median 1.08) in patients of hepatectomy and 0.47-19.90 COI (median 6.0) in transplant patients. The levels of WFA+-M2BP in liver transplant patients is much higher than that of hepatectomy patients. Overall, liver fibrotic stage was positively correlated to WFA+-M2BP levels (P<0.0001). This study demonstrated that elevated WFA+-M2BP level (COI ≥0.75) was associated with a higher HCC recurrence rate in the resection group (P<0.001). Survival analysis showed that an elevated WFA+-M2BP level (COI ≥1.43) is associated with a higher mortality risk after surgical resection (P=0.0088) in the univariate analysis only. In liver transplant patients, WFA+-M2BP level (COI ≥3.81) did not predict HCC recurrence at all, but was associated poor survival after transplantation, with a borderline significance (P=0.0943). Serum WFA+-M2BP is a reliable marker for liver fibrosis in the present study. It is also reliable marker to predict prognosis of HCC after surgical resection. However, the prognostic role of WFA+-M2BP in HCC related transplants is equivocal, which is different from that of surgical resection.  相似文献   
63.
Studies using pharmacologic inhibitors have implicated the enzyme aldose reductase in the pathogenesis of albuminuria and diabetic renal disease. However, a clear conclusion is not easily drawn from such studies since these pharmacologic inhibitors have nonspecific properties. To examine further the role of aldose reductase, we have overexpressed the human enzyme in a transgenic rat model. Transgene expression in the kidney was predominantly localized to the outer stripe of the outer medulla, compatible with the histotopography of the straight (S3) proximal tubule. The effect of enzyme overexpression on diabetes-induced renal function and structure was then investigated. Contrary to what may have been anticipated from the previous enzyme inhibition studies, diabetes-induced albuminuria was completely prevented by the overexpression of aldose reductase. No effect of overexpression of aldose reductase on renal structure nor on urinary excretion of β2-microglobulin and N-acetyl-β-d-glucosaminidase was observed in this transgenic rat model. In conclusion, our study strongly suggests that multiple roles for aldose reductase may give it a more complex place in diabetic nephropathy than is currently recognized.  相似文献   
64.
In this article, a rapid, sensitive, and disposable microfluidic immunosensor is presented for point-of-care (POC) testing and clinical diagnosis. For the first time, the blocking process is eliminated from a microfluidic heterogeneous immunoassay by using protein A functionalized polydimethylsiloxane microchannels. The nonspecific binding of the assay is maintained around the chip background level by using a pair of antibodies with different affinity to protein A under optimized experimental conditions. C-reactive protein (CRP), a biomarker for inflammation and cardiovascular disease risk assessment, is selected as a model analyte to demonstrate the sensitivity of this blocking-free microfluidic heterogeneous immunoassay. A four parameter logistic function is used to model and assess the data. The limit of detection obtained is 0.54 μg/mL, which is lower than the cut-off value for clinical diagnosis. The overall assay is completed in 5 min. The protein A modified PDMS chips wet-stored at 4°C can maintain biofunctionality up to 14 months. The developed blocking-free microfluidic heterogeneous immunoassay will immediately provide benefits to most immunosensing microdevices targeted for POC diagnostics by shortening analysis time, simplifying fluid transportation, reducing sample consumption, and lowering waste generation.  相似文献   
65.
OBJECTIVE: We had two objectives: to determine the percentage of women presenting with clinical findings whose diagnostic mammogram led to detection of a breast cancer at a site distant from the original clinical complaint and to assess the performance of computer-aided detection (CAD) on diagnostic mammography. MATERIALS AND METHODS: Three institutions contributed consecutive cases in which a mammogram was obtained to evaluate a clinical finding, after which a histologic diagnosis of breast cancer was made. Clinical data and the mammograms were reviewed to determine the nature of the clinical findings and to document the location and characteristics of 212 biopsy-proven cancers in 197 patients who met the study criteria. Standard four-view breast mammograms were then analyzed by a CAD system. RESULTS: The most common clinical finding was a palpable mass (90%, 177/197), with nipple discharge (5%, 9/197), focal tenderness or pain (2%, 5/197), and miscellaneous complaints (3%, 6/197) also noted. Two separate cancers were found in 7.6% (15/197) of the cases. In another 7.6% (15/197) of the cases, the single diagnosed cancer was not at the location of the specific clinical finding. The CAD system correctly marked 87% (26/30) of those cancers that were clinically unsuspected (i.e., not at the location of the clinical finding). CONCLUSION: Breast cancers occurred at locations other than the site of the presenting clinical finding in 15% (30/197) of patients undergoing diagnostic mammography in whom a cancer was detected. CAD identified 87% of these incidentally detected cancers and may therefore be useful as a detection aid to the radiologist when interpreting diagnostic mammograms.  相似文献   
66.
67.
68.
Accumulation of the permeant lipophilic cation [(3)H]tetraphenylphosphonium (TPP(+)) by synaptosome preparations from guinea pig brain cerebral cortex is inhibited 1:10 by medium containing 193 mM K(+) and by veratridine. A further 1:10 to 1:15 decrease in TPP(+) uptake occurs under nitrogen and in the presence of mitochondrial inhibitors such as oligomycin, whereas starvation and succinate supplementation have no effect. These data indicate that, in analogy to intact neurons, there is an electrical potential (DeltaPsi, interior negative) of -60 to -80 mV across the synaptosomal membrane that is due primarily to a K(+) diffusion gradient (K(+) (in)-->K(+) (out)). The data also indicate that mitochondria entrapped within the synaptosome but not free mitochondria make a large contribution to the TPP(+) concentration gradients observed.Conditions are defined in which tetanus toxin binds specifically and immediately to synaptosomes in media used to measure TPP(+) uptake. Under these conditions tetanus toxin induces dose-dependent changes in TPP(+) uptake that are blocked by antitoxin and not mimicked by biologically inactivated toxin preparations. The effect of tetanus toxin on TPP(+) uptake is not evident in the presence of 193 mM K(+) or veratridine but remains under conditions known to abolish the mitochondrial DeltaPsi. Moreover, tetanus toxin has no effect on TPP(+) uptake by isolated synaptosomal mitochondria. The results thus define an in vitro action of tetanus toxin on the synaptosomal membrane that can be correlated with biological potency in vivo and is consistent with the in vivo effects of tetanus toxin on neuronal transmission.  相似文献   
69.
Purpose: After a moderate to severe traumatic brain injury, it is widely recommended that family members be actively engaged in the client's rehabilitation journey because evidence suggests that this is associated with better outcomes. The ability of family members to fully engage in rehabilitation may be hindered by the barriers (logistical and psychological) they encounter. However, rehabilitation services can facilitate family engagement through a person-centred approach that provides support to remove barriers. Limited published guidance exists regarding practical and effective methods for delivering such support. This paper describes how one rehabilitation service has developed an eight-tiered approach. Key messages and implications: Family support is provided by explicit structuring of services to include (i) early engagement, (ii) meeting cultural needs, (iii) keeping families together, (iv) actively listening, (v) active involvement, (vi) education, (vii) skills training, and (viii) support for community re-integration. Implementation of these support strategies are individualised based on the expressed needs of each family. Families report a high level of satisfaction with the service. Conclusion: A practice-based quality improvement model identified challenges, implemented changes, and observed/evaluated the results to successfully develop a multifaceted strategy for supporting families, thereby encouraging their engagement in rehabilitation. Ongoing refinements and evaluation are planned. [Box: see text].  相似文献   
70.
Recruitment and retention of circulating progenitor cells at the site of injured or ischemic tissues facilitates adult neo-vascularization. We hypothesized that cell therapy could modulate local neo-vascularization through the vascular endothelial growth factor (VEGF)/stromal cell-derived factor-1 (SDF-1) axis and by paracrine effects on local endothelial cells. We isolated from rat bone marrow a subset of multipotent adult progenitor cell-derived progenitor cells (MDPC). In vitro, MDPCs secreted multiple cytokines related to inflammation and angiogenesis, including monocyte chemotactic protein-1, SDF-1, basic fibroblast growth factor, and VEGF, and expressed the chemokine receptors CXCR4 and VEGFR1. To investigate in vivo properties, we transplanted MDPCs into the ischemic hind limbs of rats. Elevated levels of the chemokine SDF-1 and colocalization of CD11b+ cells marked the initial phase of tissue remodeling after cell transplantation. Prolonged engraftment was observed in the adventitial–medial border region of arterioles of ischemic muscles. However, engrafted cells did not differentiate into endothelial or smooth muscle cells. Limb perfusion normalized 4 weeks after cell injection. Inhibition of SDF-1 reduced the engraftment of transplanted cells and decreased endothelial cell proliferation. These findings suggest a two-stage model whereby transplanted MDPCs modulate wound repair through recruitment of inflammatory cells to ischemic tissue. This is an important potential mechanism for cell transplantation, in addition to the direct modulation of local vascular cells through paracrine mechanisms.  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