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   9362篇
  免费   1002篇
  国内免费   18篇
耳鼻咽喉   60篇
儿科学   291篇
妇产科学   192篇
基础医学   1239篇
口腔科学   208篇
临床医学   1066篇
内科学   1767篇
皮肤病学   88篇
神经病学   740篇
特种医学   292篇
外国民族医学   1篇
外科学   1938篇
综合类   316篇
一般理论   12篇
预防医学   914篇
眼科学   167篇
药学   554篇
中国医学   7篇
肿瘤学   530篇
  2023年   76篇
  2022年   87篇
  2021年   224篇
  2020年   142篇
  2019年   209篇
  2018年   251篇
  2017年   191篇
  2016年   163篇
  2015年   198篇
  2014年   293篇
  2013年   408篇
  2012年   536篇
  2011年   557篇
  2010年   332篇
  2009年   273篇
  2008年   434篇
  2007年   491篇
  2006年   451篇
  2005年   402篇
  2004年   392篇
  2003年   374篇
  2002年   356篇
  2001年   225篇
  2000年   213篇
  1999年   194篇
  1998年   115篇
  1997年   104篇
  1996年   77篇
  1995年   80篇
  1994年   78篇
  1993年   54篇
  1992年   179篇
  1991年   171篇
  1990年   157篇
  1989年   126篇
  1988年   127篇
  1987年   105篇
  1986年   129篇
  1985年   117篇
  1984年   94篇
  1983年   82篇
  1982年   58篇
  1981年   50篇
  1979年   85篇
  1978年   77篇
  1976年   52篇
  1975年   53篇
  1974年   57篇
  1973年   71篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
991.
992.

Background

The Abductor hallucis muscle (AbdH) plays an integral role during gait and is often affected in pathological foot conditions. The aim of this study was to evaluate the within and between-session intra-tester reliability using diagnostic ultrasound of the dorso-plantar thickness, medio-lateral width and cross-sectional area, of the AbdH in asymptomatic adults.

Methods

The AbdH muscles of thirty asymptomatic subjects were imaged and then measured using a Philips HD11 Ultrasound machine. Interclass correlation coefficients (ICC) with 95% confidence intervals (CI) were used to calculate both within and between session intra-tester reliability.

Results

The within-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.99–0.99); medio-lateral width an ICC: of 0.97 (95% CI: 0.92–0.97) and cross-sectional area an ICC of 0.98 (95% CI: 0.98–0.99). Between-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.95 to 0.98); medio-lateral width an ICC of 0.94 (95% CI 0.90 to 0.96) and for cross-sectional area an ICC of 0.79 (95% CI 0.65 to 0.88).

Conclusion

Diagnostic ultrasound has the potential to be a reliable tool for evaluating the AbdH muscle in asymptomatic subjects. Subsequent studies may be conducted to provide a better understanding of the AbdH function in foot and ankle pathologies.  相似文献   
993.
BACKGROUND: Most centers advocate orthotopic liver transplantation (OLT) for patients with primary sclerosing cholangitis (PSC) and cirrhosis. Management of PSC patients without cirrhosis remains controversial. We examined the results of extrahepatic biliary resection (EHBR) for PSC. STUDY DESIGN: Between 1981 and 2006, 126 patients with PSC underwent EHBR (n = 77) or OLT (n = 49). Data on biliary drainage procedures, perioperative morbidity, and longterm survival were collected and analyzed. RESULTS: Of 77 patients undergoing EHBR, mean preoperative bilirubin level was 5.6 mg/dL. Nine (11.7%) patients had cirrhosis. Most patients had preoperative biliary drainage (ERCP, 61.0%; PTC, 67.5%). At operation, 73 (94.8%) patients underwent EHBR, including hepatic duct bifurcation. Most patients also had insertion of bilateral transhepatic silicone elastomer biliary stents; 4 (5.2%) underwent EHBR with stent insertion plus hepatectomy. For EHBR patients, perioperative complication rate was 38.7% and 30-day mortality was 3.9%. Bilirubin levels significantly decreased postoperatively (mean drop 3.8 mg/dL; p < 0.01). At 3 years, 57.1% of patients had no PSC-related readmissions, and 16.2% had more than 3. At a median followup of 10.5 years, 5- and 10-year survival was 76.4% and 52.7%, respectively. Cholangiocarcinoma did not develop in any patients, and only seven required OLT. Factors associated with worse survival included postoperative bilirubin >or= 2 mg/dL and history of cirrhosis (both p < 0.001). In patients undergoing EHBR, noncirrhotic patients had significantly better longterm outcomes versus cirrhotic patients (10-year survival, 60.2% versus 12.0%; p < 0.001). In contrast, 10-year survival of OLT patients with cirrhosis was 57.0%. CONCLUSIONS: Noncirrhotic patients with PSC can be successfully managed with EHBR. EHBR for noncirrhotic patients is associated with low perioperative morbidity, few readmissions, no new cholangiocarcinomas, and 10-year survival > 60%. OLT should be reserved for patients with PSC and associated hepatic cirrhosis.  相似文献   
994.
In the developing brain the majority of neurons migrate from their birthplace to their final destination. This active movement is essential for the formation of cortical layers and nuclei. The impairment of migration does not affect the viability of neurons but often results in abnormal differentiation. The proper migration of neurons requires the orchestrated activities of multiple cellular and molecular events, such as pathway selection, the activation of specific receptors and channels, and the assembly and disassembly of cytoskeletal components. The migration of neurons is very vulnerable to exposure to environmental toxins, such as alcohol. In this article, we will focus on recent developments in the migration of cerebellar granule cells. First, we will describe when, where and how granule cells migrate through different cortical layers to reach their final destination. Second, we will present how internal programs control the sequential changes in granule cell migration. Third, we will review the roles of external guidance cues and transmembrane signals in granule cell migration. Finally, we will reveal mechanisms by which alcohol exposure impairs granule cell migration.  相似文献   
995.
996.
OBJECTIVE: To determine the reliability of formal exercise testing and the reliability of functional and activity questionnaires in children with juvenile idiopathic arthritis (JIA). METHODS: Children with JIA of any subtype ages 8-16 years who were recruited to a randomized trial comparing different exercise therapies participated in 2 preintervention sessions of exercise testing 2-6 weeks apart. Exercise testing included 1) submaximal oxygen uptake (VO(2submax)), 2) peak VO(2) (VO(2peak)), and 3) anaerobic power using modified Wingate tests (W(ant)). Two physical function questionnaires (the Childhood Health Assessment Questionnaire [C-HAQ] and Revised Activity Scale for Kids [ASK]) and 1 daily physical activity questionnaire (the Habitual Activity Estimation Scale [HAES]) were also completed at these times. Test-retest reliability was assessed using type 3, intrarater intraclass correlation coefficient (ICC(3,1)) and Bland and Altman plots were used to determine limits of agreement. RESULTS: Data were available for 74 patients (58 girls). VO(2submax), VO(2peak), and W(ant) demonstrated high reliability (ICC(3,1) 0.82, 0.91, and 0.94, respectively). C-HAQ and ASK questionnaires also had very high reliability (ICC(3,1) 0.82 and 0.91, respectively). The HAES demonstrated low reliability for total activity score (ICC(3,1) 0.15) and moderate reliability when the number of very active hours was analyzed separately (ICC(3,1) 0.59). CONCLUSION: Results of this investigation suggest that exercise testing and functional questionnaires in children with JIA are consistent and reliable. Reliability of the HAES total score was poor, but moderate when the very active hours subscale score was used.  相似文献   
997.
998.
999.
Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-Ras(V12)-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-1 from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.  相似文献   
1000.
1. This commentary reviews and discusses the association between increased arterial stiffness and indices of glucose and insulin metabolism and diabetes mellitus (DM). 2. Diabetes mellitus is associated with increased cardiovascular events, is an established major independent risk factor for cardiovascular disease and is included in current risk assessment algorithms. Based on Framingham risk assessment, the incremental risk due to DM, at a given level of baseline risk in non-diabetics, is approximately equivalent to 10 years and, at any given level of other major risk factors, DM increases risk three- to fourfold. 3. Increased aortic stiffness has been shown to be an independent risk factor for both cardiovascular and overall mortality in high-risk groups and recently in the general population. Both DM1 and DM2 are associated with accelerated stiffening of the elastic arteries, over and above that associated with normal ageing, and DM can be considered as imparting added biological age and, thus, added cardiovascular risk. 4. Aortic stiffness provides a plausible mechanism relating diabetes to increase cardiovascular disease. 5. A proportion of the increased risk of cardiovascular events in DM is a sequel of stiff arteries. Direct measures of arterial stiffness, such as aortic pulse wave velocity, are likely to be better candidates than pulse wave analysis for refining interventions to improve outcomes in diabetes.  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