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   44744篇
  免费   2853篇
  国内免费   136篇
耳鼻咽喉   480篇
儿科学   1439篇
妇产科学   1214篇
基础医学   6011篇
口腔科学   956篇
临床医学   6581篇
内科学   8665篇
皮肤病学   836篇
神经病学   4278篇
特种医学   781篇
外科学   4297篇
综合类   464篇
一般理论   56篇
预防医学   5239篇
眼科学   722篇
药学   2675篇
中国医学   111篇
肿瘤学   2928篇
  2023年   248篇
  2022年   500篇
  2021年   1063篇
  2020年   619篇
  2019年   1030篇
  2018年   1201篇
  2017年   818篇
  2016年   835篇
  2015年   1046篇
  2014年   1470篇
  2013年   2178篇
  2012年   3215篇
  2011年   3366篇
  2010年   1881篇
  2009年   1564篇
  2008年   2967篇
  2007年   3007篇
  2006年   2949篇
  2005年   2768篇
  2004年   2638篇
  2003年   2494篇
  2002年   2302篇
  2001年   449篇
  2000年   422篇
  1999年   502篇
  1998年   475篇
  1997年   419篇
  1996年   352篇
  1995年   307篇
  1994年   311篇
  1993年   282篇
  1992年   300篇
  1991年   262篇
  1990年   247篇
  1989年   231篇
  1988年   197篇
  1987年   186篇
  1986年   168篇
  1985年   188篇
  1984年   204篇
  1983年   198篇
  1982年   228篇
  1981年   192篇
  1980年   182篇
  1979年   142篇
  1978年   118篇
  1977年   104篇
  1976年   101篇
  1975年   89篇
  1974年   99篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
The results of lumbar fusion in chronic low back pain (LBP) patients vary considerably, and there is a need for proper patient selection. Lumbosacral orthoses have been widely used to predict outcome, however, with little scientific support. The aim of the present study was to determine the value of a pantaloon cast test in selecting chronic LBP patients for lumbar fusion or conservative management. First, a systematic review of the literature was carried out in which two independent reviewers identified studies in Medline, Cochrane and Current Contents databases. Three papers met the selection criteria. In the only study with a control group, a significantly better outcome after fusion compared to conservative treatment was found in patients who reported significant pain relief while in a cast (i.e. a positive cast test). The results of lumbar fusion, however, were not significantly different for patients with a positive and those with a negative cast test. In addition to the review, a clinical cohort study of 257 LBP patients, who had been allocated to either lumbar fusion or conservative management by a temporary external transpedicular fixation trial, was performed. Prior to allocation, all had undergone a pantaloon cast test. Patients with no history of prior spine surgery and with a positive pantaloon cast test had a better outcome after lumbar fusion than those treated conservatively (P = 0.002, χ 2 test). In patients with previous spine operations the outcomes were poor and the test was of no value. From the literature and the present patient cohort, it was concluded that only in chronic LBP patients without prior spine surgery, a pantaloon cast test with substantial pain relief suggests a favorable outcome of lumbar fusion compared to conservative management. The test has no value in patients who have had previous spine surgery.  相似文献   
23.
Long-term daily use of gamma-hydroxybutyrate (GHB) and related compounds has recently been associated with a withdrawal syndrome. To the best of the authors' knowledge, there are currently no animal models of GHB withdrawal. OBJECTIVES: The authors studied and described the effect of chronic dosing of GHB (3-6 days) on tolerance and withdrawal in a rat model. METHODS: Rats were administered GHB every three hours via intraperitoneal catheter. Groups of rats (2 per group) were dosed with GHB for either 3 (24 doses), 4 (32 doses), 5 (40 doses), or 6 (48 doses) days. The GHB dose was 0.25 g/kg for doses 1-8, 0.75 g/kg for doses 9-12, 1 g/kg for doses 13-16, 1.25 g/kg for doses 17-24, 1.5 g/kg for doses 25-32, 1.75 g/kg for doses 33-40, and 2 g/kg for doses 41-48. Following the last dose of GHB, the rats were scored using a 16-point ethanol intoxication-withdrawal scale rating spontaneous behaviors, response to handling, grooming, and neurological signs. Lower scores indicate intoxication, while higher scores indicate withdrawal. Scores were recorded at hours 0, 1, 2, 3, 4, 5, 6, 9, 12, and 24. RESULTS: Tolerance: Rats dosed with GHB for more days were less intoxicated one hour after their last GHB dose despite receiving higher doses. WITHDRAWAL: The scores for all rats dosed with GHB increased at hours 4 (p = 0.028), 5 (p = 0.037), 6 (p = 0.007), and 9 (p = 0.024) after the last dose, indicating withdrawal. The scores demonstrated a linear increase dependent upon the number of days of GHB dosing at hours 3 (p < 0.000), 4 (p = 0.004), 5 (p = 0.002), and 12 (p = 0.039) as well as prior to the last dose at hour 0 (p = 0.000). No rats developed seizures. CONCLUSIONS: Tolerance and mild withdrawal in rats can be induced by administering intraperitoneal GHB every three hours for 3-6 days. More prolonged dosing and higher doses of GHB may be necessary to induce severe withdrawal.  相似文献   
24.
Wound healing involves a number of cellular and molecular events, many of which are controlled by soluble growth factors. In the process of healing, hepatocyte growth factor, a cytokine known to act as mitogen, motogen, and morphogen, has been postulated to play multiple roles during several stages of this complex biological process. Produced primarily by stromal fibroblasts, hepatocyte growth factor regulates angiogenesis, vascular permeability, cell migration, matrix deposition and degradation, and other biological processes. The current article discusses recent progress in understanding the multiple roles played by this growth factor in tissue repair.  相似文献   
25.
CXCL12 and its receptor, CXCR4, are emerging as promising targets for modulating growth, angiogenesis, and metastasis in several human cancers. Indeed, blocking the receptor is sufficient to prevent metastasis and angiogenesis in experimental breast cancer xenografts. Recently, the biological effect of the CXCR4 in pancreatic cancer, one of the most deadly neoplastic diseases, has been reported. However, the molecular mechanism by which CXCR4 contributes to these properties is not completely understood. In this paper, we characterize the signaling pathways activated by CXCR4 in pancreatic cancer. We show that after CXCR4 activation, EGFR becomes tyrosine phosphorylated, and the kinase activity of this receptor, together with the activation of MMPs, Src, and PI3-Kinase, is required for CXCR4-mediated ERK activation. Analysis of this cascade in pancreatic cancer cells revealed that the ERK-mediated pathway regulates genes involved in angiogenesis, such as VEGF, CD44, HIF1α, and IL-8. Furthermore, ERK blockage inhibits the migration and tube formation of endothelial cells induced by CXCL12. Considering that inhibitors for several components of this pathway, including CXCR4 itself, are at different stages of clinical trials, this study provides theoretical justification for the clinical testing of these drugs in pancreatic cancer, thus extending the list of potential targets for treating this dismal disease.  相似文献   
26.
Patricia McCarley 《Nephrology nursing journal》2006,33(4):423-6, 445; quiz 427-8
The National Kidney Foundation Kidney Disease Outcomes Quality Initiative recently published revised clinical practice guidelines and recommendations for the treatment of anemia. This article provides an overview of the new guidelines and recommendations, with a focus on the hemoglobin treatment range, iron status, use of erythropoiesis-stimulating agents, and adjuvant therapies.  相似文献   
27.
28.
Current medical procedures used in prenatal screening and diagnosis of handicapping conditions are reviewed. These strategies include ultrasound, amniocentesis, chorionic villus biopsy, restriction enzyme analysis, maternal serum analysis, fetoscopy, and fetal serum analysis. Along with an explanation of each method, advantages, disadvantages, and risks involved with each are provided. An understanding of these procedures by medical and educational personnel is encouraged, and the potential benefits of prenatal identification of handicapping conditions are emphasized.  相似文献   
29.
30.
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