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   1167篇
  免费   75篇
  国内免费   3篇
耳鼻咽喉   30篇
儿科学   22篇
妇产科学   37篇
基础医学   187篇
口腔科学   3篇
临床医学   83篇
内科学   246篇
皮肤病学   95篇
神经病学   99篇
特种医学   31篇
外科学   170篇
综合类   6篇
预防医学   137篇
眼科学   7篇
药学   45篇
中国医学   3篇
肿瘤学   44篇
  2023年   6篇
  2022年   13篇
  2021年   31篇
  2020年   17篇
  2019年   26篇
  2018年   46篇
  2017年   10篇
  2016年   22篇
  2015年   19篇
  2014年   35篇
  2013年   38篇
  2012年   52篇
  2011年   74篇
  2010年   41篇
  2009年   33篇
  2008年   46篇
  2007年   80篇
  2006年   74篇
  2005年   52篇
  2004年   50篇
  2003年   60篇
  2002年   49篇
  2001年   37篇
  2000年   43篇
  1999年   25篇
  1998年   9篇
  1996年   4篇
  1995年   9篇
  1994年   4篇
  1993年   2篇
  1992年   18篇
  1991年   16篇
  1990年   19篇
  1989年   17篇
  1988年   23篇
  1987年   24篇
  1986年   22篇
  1985年   18篇
  1984年   14篇
  1983年   10篇
  1981年   3篇
  1979年   4篇
  1978年   4篇
  1975年   3篇
  1974年   5篇
  1973年   3篇
  1972年   12篇
  1971年   9篇
  1970年   5篇
  1944年   1篇
排序方式: 共有1245条查询结果,搜索用时 15 毫秒
91.
92.
93.
A 30-year-old woman with von Willebrand's disease was admitted in labor. As epidural analgesia was ruled out due to risk of spinal hematoma, a pump for patient-controlled analgesia (PCA) was provided with boluses of remifentanil and set for intravenous infusion of 24 micrograms with a lockout time of 5 minutes. The patient reported analgesia to be satisfactory. Later, because of abnormal fetal positioning, an emergency cesarean was performed with the patient under general anesthesia with remifentanil, with propofol and succinylcholine for induction. A healthy girl was born free of respiratory depression. Von Willebrand's disease is a hemorrhagic disorder of autosomal dominant inheritance due to a quantitative or functional factor VIII deficit. Various subtypes and degrees of severity of abnormal bleeding have been described. It is the most common genetic hemostatic disorder affecting obstetric procedures, and although epidural analgesia has been used with strict hematologic monitoring, that technique carries a risk of hematoma. PCA is useful in patients for whom regional techniques are contraindicated. With adequate fetal and maternal monitoring, remifentanil in PCA is safe and more effective than other opiates for labor pain.  相似文献   
94.
The increasing costs of care make it important to identify those strategies of greatest value from both an effectiveness and cost perspective. Economic analysis is characterized by a simultaneous consideration of alternatives costs and outcomes, and can provide useful data for managerial decision making. In this paper, methods of economic evaluations in general and in cancer in particular is reviewed. In cancer treatment, preventive, curative or palliative strategies can be concerned. Economic evaluation have become increasingly important in oncology because of the proliferation of expensive new treatments. Furthermore, considering quality of life effects is particularly important in oncology, where many treatments obtain modest improvements in response or survival. Quality of life measurements are also reviewed.  相似文献   
95.
To investigate the possible role of molecular mimicry to bacterial components in multiple sclerosis (MS) pathogenesis we examined antibody responses to mimicry peptide sequences of Acinetobacter, Pseudomonas aeruginosa and myelin components. Antibodies to mimicry peptides from Acinetobacter (p<0.001), P. aeruginosa (p<0.001), myelin basic protein (MBP) (p<0.001) and myelin oligodendrocyte glycoprotein (MOG) (p<0.001) were significantly elevated in MS patients compared to controls. Antisera against MBP (residues 110-124) reacted with both Acinetobacter and Pseudomonas peptides from 4- and gamma-carboxymuconolactone decarboxylase, respectively. MOG (residues 43-57) antisera reacted with Acinetobacter peptide from 3-oxo-adipate-CoA-transferase subunit A. The role of these bacteria in MS is unclear but demonstrates that molecular mimicry is not restricted to viruses suggesting bacterial infections could play a role in MS pathogenesis. Further work is required to evaluate the relevance of these cross-reactive antibodies to the neuropathology of MS.  相似文献   
96.
97.
D-002 is a mixture of higher aliphatic alcohols isolated from beeswax that inhibits rat microsomal lipid peroxidation in vitro and in vivo. This study was undertaken to investigate whether D-002 also inhibits lipid peroxidation in older subjects. The free radical theory of aging suggests that progressive defects in the protection against free radical reactions leads to progressive deleterious effects of free radicals on cells and tissues. This free radical damage has been implicated in several pathophysiological processes associated with the chronic degenerative diseases that occur with aging. Forty-eight older subjects were randomly assigned, in a double-blind fashion, to receive placebo or D-002 tablets (50 mg/day) once daily. At baseline, D-002 and placebo groups were well matched regarding several variables. D-002 significantly reduced the susceptibility of nonfractionated plasma samples to copper-mediated lipid peroxidation. It also significantly increased the length of the lag phase (P <.001) and the total antiioxidant status (P <.05) compared with baseline and placebo. In addition, D-002 significantly decreased malondialdehyde levels (expressed in terms of thiobarbituric acid reactive substances (TBARS, P <.001) compared with baseline, but not with placebo. No significant changes on lipid peroxidation parameters were observed in the placebo group. We conclude that D-002 treatment may be useful to prevent or manage certain pathophysiological conditions in the elderly.  相似文献   
98.
The transmembrane glycoprotein CD36 has been identified in isolated cell studies as a putative transporter of long-chain fatty acids. To examine the physiological role of CD36, we studied FA uptake and metabolism by tissues of CD36 null mice after injection with two fatty acid analogs. Compared to controls, uptake was substantially reduced (50–80%) in heart, skeletal muscle, and adipose tissues of null mice. The reduction in uptake was associated with a large decrease in fatty acid incorporation into triglycerides, which could be accounted for by an accumulation of diacylglycerides. Thus CD36 facilitates a major fraction of fatty acid uptake by myocardial, skeletal muscle, and adipose tissues, where it is highly expressed. Its role in other tissues where its expression is low and cell-specific could not be determined in these studies.  相似文献   
99.
In this study we have examined 32 patients with Beckwith Wiedemann Syndrome (BWS) for mutations affecting the CDKN1C gene, including seven cases of familial BWS. Mutations were not detected in the coding region of the CDKN1C gene in any individual with BWS. However in two patients, two G/A base substitutions at adjacent positions in the 5'UTR were detected. These substitutions were also found in normal controls. Expression of CDKN1C in somatic tissues was examined in 18 of the 32 cases using semi-quantitative RT-PCR. CDKN1C expression was significantly reduced in the peripheral blood of three cases compared with controls. These results suggest that, although coding region mutations in the CDKN1C gene are rare in BWS, mutations disrupting CDKN1C expression may be found. Three of five informative patients exhibited biallelic CDKN1C expression in lymphocytes, cord blood, and kidney tissue, respectively. Biallelic expression was not associated with overall CDKN1C levels significantly different to those in controls. Patients who expressed CDKN1C biallelically, or who were low CDKN1C expressors, maintained monoallelic methylation in the Differentially Methylated Region 2 (DMR2) of the IGF2 locus. One patient expressing CDKN1C biallelically, maintained imprinted gene expression at the IGF2 locus. These results suggest that biallelic CDKN1C expression does not significantly perturb the overall levels of CDKN1C expression in somatic tissue. They also confirm other studies showing that the mechanisms associated with regulating CDKN1C expression and imprinting are separate from those regulating IGF2 imprinting.  相似文献   
100.
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