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   26421篇
  免费   1723篇
  国内免费   155篇
耳鼻咽喉   262篇
儿科学   572篇
妇产科学   464篇
基础医学   3742篇
口腔科学   648篇
临床医学   2482篇
内科学   5183篇
皮肤病学   595篇
神经病学   2947篇
特种医学   1576篇
外科学   4739篇
综合类   163篇
一般理论   7篇
预防医学   1180篇
眼科学   320篇
药学   1608篇
中国医学   38篇
肿瘤学   1773篇
  2023年   174篇
  2022年   276篇
  2021年   620篇
  2020年   411篇
  2019年   569篇
  2018年   644篇
  2017年   516篇
  2016年   623篇
  2015年   756篇
  2014年   949篇
  2013年   1124篇
  2012年   1831篇
  2011年   1936篇
  2010年   1160篇
  2009年   1073篇
  2008年   1627篇
  2007年   1645篇
  2006年   1615篇
  2005年   1535篇
  2004年   1406篇
  2003年   1312篇
  2002年   1201篇
  2001年   443篇
  2000年   420篇
  1999年   421篇
  1998年   246篇
  1997年   247篇
  1996年   162篇
  1995年   132篇
  1994年   128篇
  1993年   114篇
  1992年   242篇
  1991年   219篇
  1990年   199篇
  1989年   196篇
  1988年   165篇
  1987年   169篇
  1986年   151篇
  1985年   166篇
  1984年   124篇
  1983年   100篇
  1982年   63篇
  1981年   64篇
  1979年   74篇
  1978年   94篇
  1974年   69篇
  1973年   68篇
  1972年   75篇
  1971年   66篇
  1970年   61篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
An 11-year-old girl presenting with right upper quadrant abdominal pain was found to have a venous hemangioma of the posterior wall of the gallbladder. Radiographic, ultrasonographic, and angiographic findings of this entity, along with a review of the literature, are presented.  相似文献   
92.
We have identified three families of miniature inverted-repeat transposable elements (VulMITEs) in the genome of sugar beet (Beta vulgaris L.), evidently derived from a member of the Vulmar family of mariner transposons. While VulMITEs I are typical stowaway-like MITEs, VulMITEs II and VulMITEs III are rearranged stowaway elements of increased size. The integration of divergent moderately and highly repetitive sequences into VulMITEs II and, in particular in VulMITEs III, respectively, shows that amplification of repetitive DNA by MITEs contribute to the increase of genome size with possible implications for plant genome evolution. Fluorescent in-situ hybridization (FISH), for the first time visualizing stowaway MITE distribution on plant chromosomes, revealed a dispersed localization of VulMITEs along all B. vulgaris chromosomes. Analysis of the flanking sequences identified a dispersed repeat as target site for the integration of the stowaway element VulMITE I. Recent transposition of VulMITE I, which most likely occurred during the domestication of cultivated beets, was concluded from insertional polymorphisms between different B. vulgaris cultivars and species. Sequence data from this article have been deposited in the EMBL/GenBank Data Library under the accession nos. AM231630-AM231653 and AM259123-AM259125.  相似文献   
93.
94.
Polyunsaturated fatty acids (PUFAs) are components of cell membranes and may play an immunomodulating role in the pathogenesis of atopic dermatitis (AD). The goal was to determine the impact of PUFAs on AD by dietary supplementation of infants. Based on the parents' decision on their babies' primary feeding, mothers and newborns were randomized to the supplementation with gamma-linolenic acid (GLA) or placebo for up to 6 months. Breastfed infants received GLA by supplementing their mothers. Formula diet was commercial whey hydrolysate unsupplemented with PUFAs. Of 131 eligible infants, 24 developed AD within the first year of life. Of these, nine belonged to the exclusively breastfed group (n = 58), 14 to the combined-fed group (n = 53), and one to the never breastfed group (n = 20). We could not find an influence of GLA on the development of AD. In subjects with AD, at 1 yr of age the serum-immunoglobulin E (IgE) was the lowest in the GLA-supplemented group A-subjects. In the GLA-supplemented group, GLA-levels in breast milk were similar in atopic and non-atopic infants. In the non-supplemented group the GLA-content of breast milk was 0.07% of total fatty acids in atopic infants vs. 0.17% in non-atopic infants (p < 0.01). Dietary GLA-supplementation could not prevent AD. Interestingly, the number of infants developing AD was the lowest in never breastfed children. In infants suffering from AD, GLA-supplementation seemed to reduce total IgE in the first year of life.  相似文献   
95.
96.
In the past decade laparoscopic surgery replaced many open operations in general surgery. Apart from therapeutic uses in cholecystectomy, appendectomy, hernia surgery, gastric fundoplication, and increasingly also large intestine surgery, it is indicated diagnostically first of all for unclear abdominal findings and for staging of intra-abdominal malignancies. To date laparoscopy has been used occasionally for diagnosis and therapy of mesenteric ischemia. Patients suffering from mesenteric ischemia are usually old and have comorbid conditions. Quick diagnosis and therapy are necessary due to the pathogenesis of the disease. The low rate of morbidity as well as the easy availability of laparoscopy in principle favor the employment of laparoscopy also for mesenteric ischemia. Against the background of increasing experience in the area of laparoscopic surgery, this study gives an overview of the present value of laparoscopy for mesenteric ischemia.  相似文献   
97.
Valproic acid (VPA) is a broad-spectrum antiepileptic drug and is usually well-tolerated. Rare serious complications may occur in some patients, including haemorrhagic pancreatitis, bone marrow suppression, VPA-induced hepatotoxicity and VPA-induced encephalopathy. The typical signs of VPA-induced encephalopathy are impaired consciousness, sometimes marked EEG background slowing, increased seizure frequency, with or without hyperammonemia. There is still no proof of causative effect of VPA in patients with encephalopathy, but only of an association with an assumed causal relation. We report 19 patients with VPA-associated encephalopathy in Germany from the years 1994 to 2003, none of whom had been published previously.  相似文献   
98.
99.
Background: Hypotension due to vasodilation during subarachnoid block (SAB) for elective cesarean delivery may be harmful. Heart rate variability (HRV), reflecting autonomic control, may identify patients at risk of hypotension.

Methods: Retrospectively, HRV was analyzed in 41 patients who were classified into one of three groups depending on the decrease in systolic blood pressure (SBP): mild (SBP > 100 mmHg), moderate (100 > SBP > 80 mmHg), or severe (SBP < 80 mmHg). Prospectively, HRV and hemodynamic data of 19 patients were studied. Relative low frequency (LF), relative high frequency (HF), and LF/HF ratio were analyzed.

Results: Retrospective analysis of HRV showed a significantly higher sympathetic and lower parasympathetic drive in the groups with moderate and severe compared with mild hypotension before SAB (median, 25th/75th percentiles): LF/HF: mild: 1.2 (0.9/1.8), moderate: 2.8 (1.8/4.6), P < 0.05 versus mild; severe: 2.7 (2.0/3.5), P < 0.05 versus mild. Results were confirmed by findings of LF and HF. Prospectively, patients were grouped according to LF/HF before SAB: low-LF/HF: 1.5 (1.1/2.0) versus high-LF/HF: 4.0 (2.8/4.7), P < 0.05; low-LF: 58 +/- 9% versus high-LF: 75 +/- 10%, P < 0.05; low-HF: 41 +/- 10% versus high-HF: 25 +/- 10%, P < 0.05. High-risk patients had a significantly lower SBP after SAB (76 +/- 21 vs. 111 +/- 12 mmHg; P < 0.05).  相似文献   

100.
Electrolyte and renal hemodynamic imbalance, acute interstitial nephritis with nephrotic-range proteinuria, papillary necrosis, tubular necrosis, and vasculitis are complications after intake of nonsteroidal anti-inflammatory drugs (NSAID). We report on 2 cases of biopsy-proven granulomatous interstitial nephritis with rapidly progressing renal insufficiency. Patient 1 was on ketoprofen for 7 months and indomethacin for 10 weeks before admission to hospital. The medication was not discontinued and renal insufficiency progressed to end-stage renal failure. Renal function did not respond to steroid and tuberculostatic treatment. Patient 2 was on diclofenac for 6 months and indomethacin for 7 weeks before admission to hospital. These drugs were withdrawn at diagnosis and renal function rapidly improved. We conclude that granulomatous interstitial nephritis may be a complication of NSAID medication indicating a cell-mediated immunologic disorder. False diagnosis (sarcoidosis, tuberculosis) may lead to end-stage renal disease (case 1). Discontinuation of medication obviates further therapy (case 2).  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