首页 | 官方网站   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   1547篇
  免费   140篇
  国内免费   14篇
医药卫生   1701篇
  2024年   4篇
  2023年   34篇
  2022年   19篇
  2021年   87篇
  2020年   66篇
  2019年   86篇
  2018年   97篇
  2017年   37篇
  2016年   86篇
  2015年   78篇
  2014年   98篇
  2013年   106篇
  2012年   157篇
  2011年   153篇
  2010年   70篇
  2009年   50篇
  2008年   69篇
  2007年   83篇
  2006年   73篇
  2005年   51篇
  2004年   48篇
  2003年   39篇
  2002年   35篇
  2001年   12篇
  2000年   8篇
  1999年   6篇
  1998年   7篇
  1997年   3篇
  1996年   6篇
  1995年   6篇
  1994年   9篇
  1993年   4篇
  1992年   1篇
  1989年   2篇
  1988年   3篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1979年   1篇
  1973年   1篇
排序方式: 共有1701条查询结果,搜索用时 15 毫秒
101.
Anomalous muscles usually do not cause symptoms but are of academic interest mainly discovered during cadaveric dissection. An aberrant muscle belly arising from the index finger flexor digitorum superficialis tendon causing carpal tunnel syndrome is rare. The management of such an anatomical variant is dependent on whether the median nerve compression is associated with a palpable mass. A brief case highlighting important management principles along with a complete literature review is reported.  相似文献   
102.
Increase in pulse pressure has been shown to be predisposing factor for Coronary Artery Disease (CAD) in diverse patient populations but its relationship with the severity of CAD, particularly in the South Asians immigrant population of United States has not been demonstrated. We performed a single-center, cross-sectional study. Pulse pressure was calculated by the difference between the systolic and diastolic brachial blood pressures, and the Friesinger score (FS) was used to quantify the severity of CAD with the score of 5 used as a cutoff for extensive disease. We also sought to assess the correlation between the Friesinger score and the 10-year cardiovascular event (CVD) risk as calculated by the Framingham score. Odds ratios and 95% confidence intervals for the associations between explanatory variables and a high Friesinger score were estimated using multivariate logistic regression models. P values below .05 were considered to be statistically significant. Statistical analysis was performed using STATA version 10 software package (College Station, TX). The mean pulse pressure was significantly higher in participants with an FS of ≥5 compared with participants with an FS of <5 (63 vs. 46 mm Hg; P = .004). In univariate analysis, a pulse pressure ≥40 mm Hg was associated with a five-fold increased odds of a higher FS compared with a pulse pressure <40 mm Hg (P = .039), which was unchanged in multivariate analysis. In multivariate analysis, even after adjustment for presence of hypertension, a 10 mm Hg increase in pulse pressure was associated with a 1.97-fold increased odds of a higher FS (95% CI 1.22–3.71, P = .009). The mean Framingham score was higher in participants with a higher FS, but this difference was not significant (32.7 vs. 20.3; P = .1139). Our study demonstrates that pulse pressure, a well-established marker of vascular health, is a significant independent predictor of the severity of CAD as assessed by coronary angiography in South Asians.  相似文献   
103.
PURPOSE: Amplified MYCN oncogene defines a subgroup of neuroblastomas with poor outcome. However, a substantial number of MYCN single-copy neuroblastomas exhibits an aggressive phenotype similar to that of MYCN-amplified neuroblastomas even in the absence of high MYCN mRNA and/or protein levels. EXPERIMENTAL DESIGN: To identify shared molecular mechanisms that mediate the aggressive phenotype in MYCN-amplified and single-copy high-risk neuroblastomas, we defined genetic programs evoked by ectopically expressed MYCN in vitro and analyzed them in high-risk versus low-risk neuroblastoma tumors (n = 49) using cDNA microarrays. Candidate gene expression was validated in a separate cohort of 117 patients using quantitative PCR, and protein expression was analyzed in neuroblastoma tumors by immunoblotting and immunohistochemistry. RESULTS: We identified a genetic signature characterized by a subset of MYCN/MYC and E2F targets, including Skp2, encoding the F-box protein of the SCF(Skp2) E3-ligase, to be highly expressed in high-risk neuroblastomas independent of amplified MYCN. We validated the findings for Skp2 and analyzed its expression in relation to MYCN and E2F-1 expression in a separate cohort (n = 117) using quantitative PCR. High Skp2 expression proved to be a highly significant marker of dire prognosis independent of both MYCN status and disease stage, on the basis of multivariate analysis of event-free survival (hazard ratio, 3.54; 95% confidence interval, 1.56-8.00; P = 0.002). Skp2 protein expression was inversely correlated with expression of p27, the primary target of the SCF(Skp2) E3-ligase, in neuroblastoma tumors. CONCLUSION: Skp2 may have a key role in the progression of neuroblastomas and should make an attractive target for therapeutic approaches.  相似文献   
104.
Repeat sternotomy for left ventricular assist device insertion may result in injury to the right heart or patent coronary grafts, complicating intraoperative and postoperative management. In 4 critically ill patients, left thoracotomy was used as an alternative to repeat sternotomy. Anastomosis of the outflow conduit to the descending thoracic aorta provided satisfactory hemodynamic support.  相似文献   
105.
106.
An 11-year-old girl presented with headache of 3 months' duration. There was bilateral disc edema. The cerebrospinal fluid pressure was 50 cm of water with normal cerebrospinal fluid cytology and biochemistry. She developed severe headache (different and disabling), dizziness, vomiting, and backache on sitting up 6 hours after lumbar puncture, and lying supine relieved all of her symptoms. Intravenous fluids, analgesics, and complete bed rest did not relieve her symptoms over the next 72 hours. She was completely relieved of her symptoms on receiving two tablets of Caffergot containing 200 mg of caffeine and 2 mg of ergotamine 72 hours after lumbar puncture. The symptoms recurred 48 hours later, and a repeat dose of Caffergot was required. Magnetic resonance imaging (MRI) done 96 hours after lumbar puncture revealed the entire dura overlying the brain, including the posterior fossa, showing intense enhancement on contrast injection with leak at the lumbar puncture site. Oral caffeine (coffee, three times a day) was advised over 1 week. The patient remained asymptomatic, and a repeat MRI scan after 10 days showed complete clearing of the cerebrospinal fluid leak with no dural enhancement. The syndrome of cerebrospinal fluid hypovolemia following lumbar puncture is reported in a girl with idiopathic intracranial hypertension.  相似文献   
107.
Papazisi L  Silbart LK  Frasca S  Rood D  Liao X  Gladd M  Javed MA  Geary SJ 《Vaccine》2002,20(31-32):3709-3719
The aim of this study was to assess the efficacy of a modified live Mycoplasma gallisepticum vaccine (GT5) for the protection of chickens against infection and respiratory disease. GT5 was constructed by the reconstitution of the avirulent high passage R (R(high)) strain with the gene encoding the major cytadhesin GapA. GT5 expressed GapA on its surface yet retained the phenotypic characteristics of the parental R(high) strain. Birds vaccinated with GT5 were protected upon challenge with the virulent low passage R (R(low)) strain as evidenced by a complete absence of tracheal lesions 2 and 4 weeks post-challenge, in contrast to sham immunized/challenged control birds. Modest amounts of IgG, and little, if any secretory IgA or IgM anti-M. gallisepticum were found in tracheal washings following vaccination. However, copious amounts of specific IgA were found following challenge, especially in sham immunized birds. This suggests that the tracheal IgG elicited by GT5 vaccination may have been responsible for blocking the initial colonization of R(low), thereby resulting in protection.  相似文献   
108.
109.
110.
Iqbal J  Manley TR  Ciofi P  Clarke IJ 《Endocrinology》2005,146(11):4776-4785
Various neuropeptides and neurotransmitters affect GH secretion by acting on GHRH and somatostatin (SRIF) cells. GH secretion is also affected by alteration in adiposity, which could be via modulation of GHRH and SRIF cells. We quantified colocalization of neuropeptides in GHRH and SRIF cells and afferent projections to these cells in lean (food restricted) and normally fed sheep (n=4/group). The number of GHRH-immunoreactive (IR) cells in the arcuate nucleus was higher in lean animals, but the number of SRIF-IR cells in the periventricular nucleus was similar in the two groups. A subpopulation of GHRH-IR cells colocalized neuropeptide Y in lean animals, but this was not seen in normally fed animals. GHRH/galanin (GAL) colocalization was higher in lean animals with no difference in numbers of GHRH/tyrosine hydroxylase or GHRH/GAL-like peptide cells. SRIF/enkephalin colocalization was lower in lean animals. The percentage of GHRH neurons receiving SRIF input was similar in lean and normally fed animals, but more GHRH cells received input from enkephalin afferents in normally fed animals. The percentage of SRIF cells receiving GHRH, neuropeptide Y, GAL, and orexin afferents was higher in lean animals. These findings provide an anatomical evidence of central mechanism(s) by which appetite-regulating peptides and dopamine could regulate GH secretion. Increased input to SRIF cells in lean animals may be inhibitory and permissive of increased GH. The appearance of NPY in GHRH cells of lean animals may be a mechanism for regulation of increasing GH secretion with reduced adiposity.  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-23

京公网安备 11010802026262号