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   19581篇
  免费   1259篇
  国内免费   88篇
耳鼻咽喉   149篇
儿科学   510篇
妇产科学   512篇
基础医学   2650篇
口腔科学   459篇
临床医学   2108篇
内科学   4523篇
皮肤病学   330篇
神经病学   1685篇
特种医学   489篇
外科学   2403篇
综合类   94篇
一般理论   10篇
预防医学   1450篇
眼科学   338篇
药学   1360篇
中国医学   44篇
肿瘤学   1814篇
  2023年   136篇
  2022年   228篇
  2021年   488篇
  2020年   314篇
  2019年   476篇
  2018年   504篇
  2017年   428篇
  2016年   469篇
  2015年   479篇
  2014年   600篇
  2013年   848篇
  2012年   1295篇
  2011年   1348篇
  2010年   720篇
  2009年   646篇
  2008年   1134篇
  2007年   1158篇
  2006年   1048篇
  2005年   1098篇
  2004年   1004篇
  2003年   938篇
  2002年   883篇
  2001年   406篇
  2000年   358篇
  1999年   360篇
  1998年   202篇
  1997年   144篇
  1996年   141篇
  1995年   122篇
  1994年   101篇
  1993年   103篇
  1992年   278篇
  1991年   260篇
  1990年   246篇
  1989年   232篇
  1988年   196篇
  1987年   184篇
  1986年   191篇
  1985年   141篇
  1984年   119篇
  1983年   110篇
  1982年   64篇
  1980年   44篇
  1979年   73篇
  1978年   64篇
  1977年   50篇
  1975年   44篇
  1974年   55篇
  1973年   52篇
  1972年   49篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
1.
ObjectiveSpinal cord stimulation (SCS) is an effective treatment in failed back surgery syndrome (FBSS). We studied the effect of preimplantation opioid use on SCS outcome and the effect of SCS on opioid use during a two-year follow-up period.Materials and methodsThe study cohort included 211 consecutive FBSS patients who underwent an SCS trial from January 1997 to March 2014. Participants were divided into groups, which were as follows: 1) SCS trial only (n = 47), 2) successful SCS (implanted and in use throughout the two-year follow-up period, n = 131), and 3) unsuccessful SCS (implanted but later explanted or revised due to inadequate pain relief, n = 29). Patients who underwent explantation for other reasons (n = 4) were excluded. Opioid purchase data from January 1995 to March 2016 were retrieved from national registries.ResultsHigher preimplantation opioid doses associated with unsuccessful SCS (ROC: AUC = 0.66, p = 0.009), with 35 morphine milligram equivalents (MME)/day as the optimal cutoff value. All opioids were discontinued in 23% of patients with successful SCS, but in none of the patients with unsuccessful SCS (p = 0.004). Strong opioids were discontinued in 39% of patients with successful SCS, but in none of the patients with unsuccessful SCS (p = 0.04). Mean opioid dose escalated from 18 ± 4 MME/day to 36 ± 6 MME/day with successful SCS and from 22 ± 8 MME/day to 82 ± 21 MME/day with unsuccessful SCS (p < 0.001).ConclusionsHigher preimplantation opioid doses were associated with SCS failure, suggesting the need for opioid tapering before implantation. With continuous SCS therapy and no explantation or revision due to inadequate pain relief, 39% of FBSS patients discontinued strong opioids, and 23% discontinued all opioids. This indicates that SCS should be considered before detrimental dose escalation.  相似文献   
2.
Lessons Learned
  • The combination of trametinib and sorafenib has an acceptable safety profile, albeit at doses lower than approved for monotherapy.
  • Maximum tolerated dose is trametinib 1.5 mg daily and sorafenib 200 mg twice daily.
  • The limited anticancer activity observed in this unselected patient population does not support further exploration of trametinib plus sorafenib in patients with hepatocellular carcinoma.
BackgroundThe RAS/RAF/MEK/ERK signaling pathway is associated with proliferation and progression of hepatocellular carcinoma (HCC). Preclinical data suggest that paradoxical activation of the MAPK pathway may be one of the resistance mechanisms of sorafenib; therefore, we evaluated trametinib plus sorafenib in HCC.MethodsThis was a phase I study with a 3+3 design in patients with treatment‐naïve advanced HCC. The primary objective was safety and tolerability. The secondary objective was clinical efficacy.ResultsA total of 17 patients were treated with three different doses of trametinib and sorafenib. Two patients experienced dose‐limiting toxicity, including grade 4 hypertension and grade 3 elevation of aspartate aminotransferase (AST)/alanine aminotransferase (ALT)/bilirubin over 7 days. Maximum tolerated dose was trametinib 1.5 mg daily and sorafenib 200 mg twice a day. The most common grade 3/4 treatment‐related adverse events were elevated AST (37%) and hypertension (24%). Among 11 evaluable patients, 7 (63.6%) had stable disease with no objective response. The median progression‐free survival (PFS) and overall survival (OS) were 3.7 and 7.8 months, respectively. Phosphorylated‐ERK was evaluated as a pharmacodynamic marker, and sorafenib plus trametinib inhibited phosphorylated‐ERK up to 98.1% (median: 81.2%) in peripheral blood mononuclear cells.ConclusionTrametinib and sorafenib can be safely administered up to trametinib 1.5 mg daily and sorafenib 200 mg twice a day with limited anticancer activity in advanced HCC.  相似文献   
3.
4.
5.
6.
Purpose: Non-ambulatory persons with cerebral palsy are prone to low bone mineral density. In ambulatory persons with cerebral palsy, bone mineral density deficits are expected to be small or absent, but a consensus conclusion is lacking. In this systematic review bone mineral density in ambulatory persons with cerebral palsy (Gross Motor Function Classification Scales I–III) was studied.

Materials and methods: Medline, Embase, and Web of Science were searched. According to international guidelines, low bone mineral density was defined as Z-score?≤??2.0. In addition, we focused on Z-score?≤??1.0 because this may indicate a tendency towards low bone mineral density.

Results: We included 16 studies, comprising 465 patients aged 1–65?years. Moderate and conflicting evidence for low bone mineral density (Z-score?≤??2.0) was found for several body parts (total proximal femur, total body, distal femur, lumbar spine) in children with Gross Motor Function Classification Scales II and III. We found no evidence for low bone mineral density in children with Gross Motor Function Classification Scale I or adults, although there was a tendency towards low bone mineral density (Z-score?≤??1.0) for several body parts.

Conclusions: Although more high-quality research is needed, results indicate that deficits in bone mineral density are not restricted to non-ambulatory people with cerebral palsy.

  • Implications for Rehabilitation
  • Although more high-quality research is needed, including adults and fracture risk assessment, the current study indicates that deficits in bone mineral density are not restricted to non-ambulatory people with CP.

  • Health care professionals should be aware that optimal nutrition, supplements on indication, and an active lifestyle, preferably with weight-bearing activities, are important in ambulatory people with CP, also from a bone quality point-of-view.

  • If indicated, medication and fall prevention training should be prescribed.

  相似文献   
7.
The feasibility of ventilation imaging with hyperpolarized (HP) 129Xe MRI has been investigated for quantitative and regional assessment of ventilation in spontaneously breathing mice. The multiple breath ventilation imaging technique was modified to the protocol of spontaneous inhalation of HP 129Xe delivered continuously from a 129Xe polarizer. A series of 129Xe ventilation images was obtained by varying the number of breaths before the 129Xe lung imaging. The fractional ventilation, r, was successfully evaluated for spontaneously breathing mice. An attempt was made to detect ventilation dysfunction in the emphysematous mouse lung induced by intratracheal administration of porcine pancreatic elastase (PPE). As a result, the distribution of fractional ventilation could be visualized by the r map. Significant dysfunction of ventilation was quantitatively identified in the PPE‐treated group. The whole‐lung r value of 0.34 ± 0.01 for control mice (N = 4) was significantly reduced, to 0.25 ± 0.07, in PPE‐treated mice (N = 4) (p = 0.038). This study is the first application of multiple breath ventilation imaging to spontaneously breathing mice, and shows that this methodology is sensitive to differences in the pulmonary ventilation. This methodology is expected to improve simplicity as well as noninvasiveness when assessing regional ventilation in small rodents. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
8.

Background

Controversy continues as to whether single-incision laparoscopic cholecystectomy, with the somewhat larger incision at the umbilicus, may lead to a worse postoperative quality of life and more pain compared with the more classic 4-port laparoscopic cholecystectomy. The aim of this study was to compare single-incision and 4-port laparoscopic cholecystectomy from the perspective of quality of life.

Methods

This study was a multicenter, parallel-group, open-label, randomized clinical trial. A total of 120 patients who were scheduled to undergo elective cholecystectomy were randomly assigned 1:1 into the single-incision laparoscopic cholecystectomy or the 4-port laparoscopic cholecystectomy group and then assessed continuously for 2 weeks during the postoperative period. The primary outcome was quality of life, defined as the time to resume normal daily activities. Postoperative pain was also assessed. To explore the heterogeneity of treatment effects, we assessed the interactions of sex, age, and working status on recovery time.

Results

A total of 58 patients in the single-incision group and 53 in the 4-port group (n?=?111, 47 male, mean age 57 years) were analyzed. The mean time to resume daily activities was 10.2 days and 8.8 days, respectively, for single-incision and 4-port laparoscopic cholecystectomy (95% confidence interval –0.4 to 3.2, P?=?.12). Similarly, the time to relief from postoperative pain did not differ significantly between the groups. Statistically insignificant but qualitative interactions were noted; in the subgroups of women, full-time workers, and patients younger than 60 years, recovery tended to be slower after single-incision laparoscopic cholecystectomy.

Conclusion

Postoperative quality of life did not differ substantially between single-incision laparoscopic cholecystectomy and 4-port laparoscopic cholecystectomy. Patients younger than 60 years, women, and full-time workers tended to have a somewhat slower recovery after single-incision laparoscopic cholecystectomy.  相似文献   
9.
10.
One diagnostic criterion for metabolic syndrome is obesity from the accumulation of visceral fat; others include abdominal circumference and area of visceral fat as measured by computed tomography (CT) at the umbilical level. We evaluated visceral fat using frequency-selective excitation magnetic resonance (MR) imaging SPAIR (spectral attenuation with inversion recovery) water suppression THRIVE (3D T1-high resolution isotropic volume examination). Fifty of 70 slices with 2-mm interval were used to render and measure volume of visceral fat ranging within 10 cm of the umbilicus; the area of visceral fat at the umbilical level was also measured. Imaging was completed using breath hold within 14 s. Image processing was easier than using CT.  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