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   3526篇
  免费   242篇
  国内免费   2篇
耳鼻咽喉   33篇
儿科学   110篇
妇产科学   94篇
基础医学   410篇
口腔科学   36篇
临床医学   631篇
内科学   519篇
皮肤病学   58篇
神经病学   324篇
特种医学   66篇
外科学   343篇
综合类   39篇
一般理论   5篇
预防医学   499篇
眼科学   80篇
药学   232篇
中国医学   17篇
肿瘤学   274篇
  2023年   19篇
  2022年   28篇
  2021年   59篇
  2020年   41篇
  2019年   49篇
  2018年   74篇
  2017年   57篇
  2016年   67篇
  2015年   88篇
  2014年   87篇
  2013年   182篇
  2012年   236篇
  2011年   282篇
  2010年   140篇
  2009年   112篇
  2008年   242篇
  2007年   272篇
  2006年   233篇
  2005年   226篇
  2004年   256篇
  2003年   219篇
  2002年   195篇
  2001年   20篇
  2000年   24篇
  1999年   36篇
  1998年   40篇
  1997年   41篇
  1996年   30篇
  1995年   29篇
  1994年   20篇
  1993年   18篇
  1992年   19篇
  1991年   38篇
  1990年   7篇
  1989年   17篇
  1988年   19篇
  1987年   14篇
  1986年   15篇
  1985年   22篇
  1984年   19篇
  1983年   23篇
  1982年   25篇
  1981年   22篇
  1980年   20篇
  1978年   11篇
  1977年   9篇
  1976年   5篇
  1975年   5篇
  1974年   6篇
  1928年   5篇
排序方式: 共有3770条查询结果,搜索用时 31 毫秒
31.
32.
PURPOSE: The availability of noninvasive techniques to detect the effects of antiangiogenic agents is critically important for optimizing treatment of cancer with these agents. Magnetic resonance imaging (MRI) is one such noninvasive technique that is routinely used clinically. EXPERIMENTAL DESIGN: In this study, we have evaluated the use of MRI of the intravascular contrast agent albumin-GdDTPA to detect the effects of the antiangiogenic agent TNP-470 on the vascular volume and permeability of the MatLyLu prostate cancer model. RESULTS: TNP-470-treated tumors demonstrated a significant decrease of vascular volume, as well as a significant reduction in vascular and permeable regions, compared with volume-matched control tumors. Although the fractional volume of permeable regions in the tumor decreased, the average value of tumor permeability did not decrease significantly. This was attributable to increase in permeability in some regions of the tumor. These regions were mostly associated with low vascular volume. ELISA assays of control and treated MatLyLu tumors also detected a significant increase of vascular endothelial growth factor in the TNP-470-treated tumors. CONCLUSION: MRI detected significant changes in tumor vascular characteristics after treatment with TNP-470.  相似文献   
33.
PURPOSE: To prospectively assess potential risk factors for relapse in clinical stage I nonseminomatous germ cell tumors of the testis (CS I NSGCT). PATIENTS AND METHODS: From September 1996 to May 2002, 200 patients with CS I NSGCT were prospectively assigned to retroperitoneal lymph node dissection (RPLND), and risk factor assessment was performed within a multicenter protocol. One hundred sixty-five patients had an adequate minimum follow-up of 12 months (mean, 34.5 months) or had pathologic stage II. RESULTS: Pathologic stage II disease was found in 27.9% of patients. Only 0.6% of patients relapsed in the retroperitoneum after confirmation of pathologic stage I disease. With reference pathology, vascular invasion (VI) was most predictive of stage in multifactorial analysis (accuracy, 65.1%). However, the positive predictive value (PPV) of VI to predict patients who have metastatic disease or relapse during follow-up was only 52.7%. With absent VI, low-risk patients had a negative predictive value (NPV) of 76.9%. With a combination of several risk factors, the PPV increased to 63.6% and the negative predictive value increased to 86.5%. CONCLUSION: Even with an optimal combination of prognostic factors and reference pathology, more than one third of patients predicted to have pathologic stage II or relapse during follow-up will not harbor metastatic disease and, therefore, would be overtreated with adjuvant therapy. However, patients at low risk may be predicted at an 86.5% level, and thus, surveillance in highly compliant patients would be a valuable option. For high-risk patients, further reduction of adjuvant treatment is necessary.  相似文献   
34.
A field of study for public health finance has never been adequately developed. Consequently, very little is known about the relationships, types, and amount of finances that fund the public health system in America. This research was undertaken to build on the sparse knowledge of public health finance by examining the value of performance measurement systems to financial analysis. A correlational study was conducted to examine the associations between public health system performance of the 10 essential public health services and funding patterns of 50 local health departments in a large state. The specific objectives were to investigate if different levels and types of revenues, expenditures, and other demographic variables in a jurisdiction are correlated to performance. Pearson correlation analysis did not conclusively show strong associations; however, statistically significant positive associations primarily between higher levels of performance and jurisdiction taxes per capita were found.  相似文献   
35.
IntroductionPuberty suppression by means of gonadotropin‐releasing hormone analogues (GnRHa) is used for young transsexuals between 12 and 16 years of age. The purpose of this intervention is to relieve the suffering caused by the development of secondary sex characteristics and to provide time to make a balanced decision regarding actual gender reassignment.AimTo compare psychological functioning and gender dysphoria before and after puberty suppression in gender dysphoric adolescents.MethodsOf the first 70 eligible candidates who received puberty suppression between 2000 and 2008, psychological functioning and gender dysphoria were assessed twice: at T0, when attending the gender identity clinic, before the start of GnRHa; and at T1, shortly before the start of cross‐sex hormone treatment.Main Outcome MeasuresBehavioral and emotional problems (Child Behavior Checklist and the Youth‐Self Report), depressive symptoms (Beck Depression Inventory), anxiety and anger (the Spielberger Trait Anxiety and Anger Scales), general functioning (the clinician's rated Children's Global Assessment Scale), gender dysphoria (the Utrecht Gender Dysphoria Scale), and body satisfaction (the Body Image Scale) were assessed.ResultsBehavioral and emotional problems and depressive symptoms decreased, while general functioning improved significantly during puberty suppression. Feelings of anxiety and anger did not change between T0 and T1. While changes over time were equal for both sexes, compared with natal males, natal females were older when they started puberty suppression and showed more problem behavior at both T0 and T1. Gender dysphoria and body satisfaction did not change between T0 and T1. No adolescent withdrew from puberty suppression, and all started cross‐sex hormone treatment, the first step of actual gender reassignment.ConclusionPuberty suppression may be considered a valuable contribution in the clinical management of gender dysphoria in adolescents. de Vries ALC, Steensma TD, Doreleijers TAH, and Cohen‐Kettenis PT. Puberty suppression in adolescents with gender identity disorder: A prospective follow‐up study. J Sex Med 2011;8:2276–2283.  相似文献   
36.
37.
Specificity of acupoints remains a crucial question in acupuncture research. The aim was to investigate whether acupuncture of specific points influences the Cortical Auditory Evoked Potentials (CAEP). Ten healthy volunteers were enrolled in this study according to inclusion criteria. One of 4 acupoints: TH3, GB43 (both claimed as specific for auditory system by Traditional Chinese Medicine) and non-specific points H7 and ST44, was stimulated during one session. Each volunteer received 4 sessions of acupuncture with an interval of 1 week between the sessions. The latencies and amplitudes of CAEP were registered before and after the acupuncture during each session. The mean peak latencies of P2 component decreased after stimulation of TH3 by 11 ms and GB43 by 14 ms whereas the peak latencies of N2 component increased after stimulation of TH3 by 9 ms and GB43 by 4 ms compared to baseline values (p<0.05). The stimulation of H7 and ST44 did not produce any changes. These findings confirm the specificity of acupuncture points TH3 and GB43 in relation to auditory system.  相似文献   
38.
39.
Alcohol consumption during pregnancy has negative implications for maternal and child health. Appropriate early universal Screening, Brief Intervention and Referral to Treatment (SBIRT) for pregnant women is necessary to identify women at risk and reduce the likelihood of continued drinking. Because SBIRT is not consistently used, the development and use of performance measures to assure implementation of SBIRT are key steps towards intervention and reduction of alcohol consumption during pregnancy. Practice guidelines provide ample support for specific instruments designed for SBIRT in prenatal care. An examination of existing performance measures related to alcohol consumption during pregnancy, however, reveals no comprehensive published performance measure designed to quantify the use of SBIRT for alcohol use in prenatal care. Process performance measures were developed that can determine the proportion of pregnant women who are screened during the course of prenatal care and the proportion of women requiring either brief intervention or referral to substance use disorder treatment who received those interventions. The measures require use of screening instruments validated for use with pregnant women. The two proposed measures would represent a significant step in efforts to assure appropriate intervention for women who drink during pregnancy, hold accountable providers who do not employ SBIRT, and provide a basis from which necessary systemic changes might occur. Pregnancy is a time when many women are motivated to stop drinking. That opportunity should be seized, with timely intervention offering assistance for pregnant women who have not stopped drinking of their own accord.  相似文献   
40.
A novel Hendra virus variant, genotype 2, was recently discovered in a horse that died after acute illness and in Pteropus flying fox tissues in Australia. We detected the variant in flying fox urine, the pathway relevant for spillover, supporting an expanded geographic range of Hendra virus risk to horses and humans.  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