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   23655篇
  免费   1796篇
  国内免费   41篇
耳鼻咽喉   225篇
儿科学   909篇
妇产科学   621篇
基础医学   3240篇
口腔科学   668篇
临床医学   2637篇
内科学   4663篇
皮肤病学   325篇
神经病学   1920篇
特种医学   901篇
外科学   3176篇
综合类   387篇
一般理论   44篇
预防医学   2290篇
眼科学   371篇
药学   1516篇
  1篇
中国医学   21篇
肿瘤学   1577篇
  2022年   133篇
  2021年   367篇
  2020年   249篇
  2019年   390篇
  2018年   423篇
  2017年   348篇
  2016年   364篇
  2015年   457篇
  2014年   616篇
  2013年   823篇
  2012年   1203篇
  2011年   1311篇
  2010年   700篇
  2009年   602篇
  2008年   1157篇
  2007年   1278篇
  2006年   1184篇
  2005年   1155篇
  2004年   1053篇
  2003年   1001篇
  2002年   878篇
  2001年   647篇
  2000年   638篇
  1999年   531篇
  1998年   250篇
  1997年   209篇
  1996年   213篇
  1995年   222篇
  1994年   205篇
  1993年   182篇
  1992年   481篇
  1991年   472篇
  1990年   444篇
  1989年   437篇
  1988年   409篇
  1987年   355篇
  1986年   310篇
  1985年   384篇
  1984年   299篇
  1983年   264篇
  1982年   166篇
  1979年   212篇
  1978年   184篇
  1977年   154篇
  1976年   148篇
  1975年   158篇
  1974年   159篇
  1973年   199篇
  1972年   160篇
  1971年   143篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: To estimate whether polymorphisms in the collagen 1Alpha1 gene (COL1Alpha1) and the transforming growth factor-beta gene (TGF-beta;1) are more common in women with cervical insufficiency than in those without the condition. METHODS: Medical, obstetric, and family histories and blood were obtained from women with (n=121) and those without (n=165) cervical insufficiency. DNA was extracted and purified by using commercial DNA isolation kits. Samples were analyzed for variants in two genes, the COL1A1 intron 1SP1 and TGF-beta Arg-25-Pro polymorphism, by using an allele-specific polymerase chain reaction assay. RESULTS: Thirty-four of 125 (27.2%) women with cervical insufficiency had at least one first-degree female relative affected. The frequency of the homozygous TT genotype in the COL1A1 gene was increased in women with a history of cervical insufficiency compared with controls (10.8% compared with 3.1%, P=.04). The TGF-beta polymorphisms (ArgPro and ProPro) also were increased in cases (38.3% compared with 14.6%, P<.001). CONCLUSION: Over one fourth of women with cervical insufficiency have a family history of cervical insufficiency, and the COL1A1 intron 1SP1 and TGF-beta Arg-25-Pro polymorphisms are associated with the condition. These observations suggest that, in part, cervical insufficiency is mediated by genetic factors. LEVEL OF EVIDENCE: II.  相似文献   
992.
993.
Less than one percent of individuals with Down syndrome exhibit mosaicism, a biological phenomenon that describes an individual who has two or more genetically distinct cell lines. The percentage of mosaicism in different tissues can impact the presence of clinical findings and hinder cytogenetic diagnosis. We report a case of mosaicism for trisomy 21 diagnosed after multi‐tissue cytogenetic analysis of peripheral blood and buccal mucosa, associated with significant intellectual disability, dysmorphic facial features, congenital heart defects, macropenis, and imperforate anus.  相似文献   
994.
Enhanced Recovery After Surgery (ERAS) is a global surgical quality improvement program that started in colorectal surgery and has now expanded to numerous specialties, including gynecologic oncology. ERAS guidelines comprise multidisciplinary, evidence-based recommendations in the preoperative, intraoperative, and postoperative period; these interventions broadly encompass patient education, anesthetic choice, multimodal pain control, avoidance of unnecessary drains, maintenance of nutrition, and prevention of emesis. Implementation of ERAS has been shown to be associated with improved clinical outcomes (length of hospital stay, complications, readmissions) and cost. Marx and colleagues first demonstrated the feasibility of ERAS in gynecologic oncology in 2003; since then, over 30 comparative studies and 4 guidelines have been published encompassing major gynecologic surgery, cytoreductive surgery, and vulvar/vaginal surgery. Implementation of ERAS in gynecologic oncology has been demonstrated to provide improvements in length of stay, complications, cost, opioid use, and patient satisfaction. Increased compliance with ERAS guidelines has been associated with greater improvement in outcomes.  相似文献   
995.
Literature that addresses the diagnosis of mental disorder in adolescents strongly suggests that it may not be possible to do so. Schizophrenic thinking, in particular, has been seen as generally characteristic of adolescents. Making judgments of specific responses from the Rorschach, the WAIS, and the WIST, 10 expert clinicians were able to make judgments with regard to 12 adolescents in the 16–19 age range that were suprisingly accurate in discriminating among schizophrenics, nonschizophrenic hospitalized adolescents, and a normal control group. Results indicate that schizophrenic thinking is not necessarily characteristic of adolescents and that information from the WIST may be helpful in identifying schizophrenic adolescents.  相似文献   
996.
997.
998.
The wide application of additive manufacturing in dentistry implies the further investigation into oral micro-organism adhesion and biofilm formation on vat-photopolymerization (VP) dental resins. The surface characteristics and microbiological analysis of a VP dental resin, printed at resolutions of 50 μm (EG-50) and 100 μm (EG-100), were evaluated against an auto-polymerizing acrylic resin (CG). Samples were evaluated using a scanning electron microscope, a scanning white-light interferometer, and analyzed for Candida albicans (CA) and Streptococcus mutans (SM) biofilm, as well as antifungal and antimicrobial activity. EG-50 and EG-100 exhibited more irregular surfaces and statistically higher mean (Ra) and root-mean-square (rms) roughness (EG-50-Ra: 2.96 ± 0.32 µm; rms: 4.05 ± 0.43 µm/EG-100-Ra: 3.76 ± 0.58 µm; rms: 4.79 ± 0.74 µm) compared to the CG (Ra: 0.52 ± 0.36 µm; rms: 0.84 ± 0.54 µm) (p < 0.05). The biomass and extracellular matrix production by CA and SM and the metabolic activity of SM were significantly decreased in EG-50 and EG-100 compared to CG (p < 0.05). CA and SM growth was inhibited by the pure unpolymerized VP resin (48 h). EG-50 and EG-100 recorded a greater irregularity, higher surface roughness, and decreased CA and SM biofilm formation over the CG.  相似文献   
999.
We studied the effect of leaks around the endotracheal tube (ETT) on the measurement of pulmonary mechanics during mechanical ventilation. We also evaluated the influence of different ventilator settings on the magnitude of leak. An adjustable leak was created at the end of the ETT in a lung model with constant compliance. Flow, tidal volume, and pressure changes were measured above and below the leak. Compliance (Ci) and resistance (Ri) during inspiration were determined by linear regression analysis (LRA) using the equation of motion and the Mead and Wittenberger method (MWM). The ventilatory change that influenced the degree of leak most was prolongation of inspiratory time (Ti). The presence of a leak around the ETT resulted in an overestimation of the Ci and Ri values, which was proportional to the size of the leak. This overestimation was also influenced by the method used to determine Ci and Ri. Because the contribution of the leak to the tidal volume progressively increased as inspiration continued, methods of analysis that depended mainly on measurement points at the end of inspiration showed a larger deviation from the true Ci and Ri values than methods mainly influenced by measurement points at the beginning of inspiration. Because of this, shortening of inspiration, or analysis of points at the beginning of inspiration reduces the error in the measurements of Ci and Ri when a leak is present. Breaths with a large leak should be excluded from any analysis of pulmonary mechanics. Pediatr Pulmonol. 1996; 22:35–43. © 1996 Wiley-Liss, Inc.  相似文献   
1000.
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