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   14360篇
  免费   1454篇
  国内免费   995篇
耳鼻咽喉   117篇
儿科学   193篇
妇产科学   135篇
基础医学   1645篇
口腔科学   289篇
临床医学   1860篇
内科学   2186篇
皮肤病学   141篇
神经病学   701篇
特种医学   630篇
外国民族医学   11篇
外科学   1277篇
综合类   2579篇
现状与发展   3篇
一般理论   1篇
预防医学   1021篇
眼科学   477篇
药学   1524篇
  16篇
中国医学   825篇
肿瘤学   1178篇
  2024年   19篇
  2023年   217篇
  2022年   318篇
  2021年   679篇
  2020年   566篇
  2019年   485篇
  2018年   483篇
  2017年   456篇
  2016年   395篇
  2015年   609篇
  2014年   747篇
  2013年   680篇
  2012年   1083篇
  2011年   1208篇
  2010年   869篇
  2009年   728篇
  2008年   743篇
  2007年   856篇
  2006年   755篇
  2005年   728篇
  2004年   483篇
  2003年   425篇
  2002年   380篇
  2001年   312篇
  2000年   326篇
  1999年   316篇
  1998年   292篇
  1997年   236篇
  1996年   186篇
  1995年   154篇
  1994年   122篇
  1993年   91篇
  1992年   107篇
  1991年   84篇
  1990年   85篇
  1989年   90篇
  1988年   79篇
  1987年   76篇
  1986年   59篇
  1985年   40篇
  1984年   24篇
  1983年   19篇
  1982年   18篇
  1981年   15篇
  1980年   9篇
  1977年   11篇
  1975年   10篇
  1969年   8篇
  1932年   10篇
  1930年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目的 了解非梗阻性无精子症患者的生育生活质量现状及其影响因素。 方法 选取生殖中心就诊的311例非梗阻性无精子症患者,采用一般情况问卷、简明中文版生育生活质量量表及社会支持评定量表进行横断面问卷调查。 结果 非梗阻性无精子症患者生育生活质量得分为(65.55±13.52)分。回归分析显示,不育年限、家庭年收入、接受辅助生殖技术治疗次数和社会支持为非梗阻性无精子症患者生育生活质量的影响因素,可解释总变异的35.4%。 结论 非梗阻性无精子症患者生育生活质量较低,医护人员应重点关注不育年限长、家庭收入低、接受辅助生殖技术治疗次数多及社会支持水平低者,采取针对性干预措施提高其生活质量。  相似文献   
52.
This study aimed to determine whether changes in contrast-enhanced computed tomography (CT) parameters could predict postsurgery overall and progression-free survival (PFS) in pancreatic cancer patients. Seventy-nine patients with a final pathological diagnosis of pancreatic adenocarcinoma were included in this study from June 2008 to August 2012. Dynamic contrast-enhanced (DCE) CT of tumors was obtained before curative-intent surgery. Absolute enhancement change (AEC) and relative enhancement change (REC) were evaluated on DCE-CT. PFS and overall survival (OS) were compared based on CT enhancement patterns. The markers of fibrogenic alpha-smooth muscle antigen (α-SMA) and periostin in tumor specimens were evaluated by immunohistochemical staining. The χ2 test was performed to determine whether CT enhancement patterns were associated with α-SMA-periostin expression levels (recorded as positive or negative). Lower REC (<0.9) was associated with shorter PFS (HR 0.51, 95% CI: 0.31–0.89) and OS (HR 0.44, 95% CI: 0.25–0.78). The α-SMA and periostin expression level were negatively correlated with REC (both P = 0). Among several CT enhancement parameters, REC was the best predictor of patient postsurgery survival. Low REC was associated with a short progression-free time and poor survival. The pathological studies suggested that REC might be a reflection of cancer fibrogenic potential.  相似文献   
53.
目的 评价长鞘联合大球囊阻断技术在破裂腹主动脉瘤腔内治疗的效果及其治疗经验.方法 回顾性分析新疆维吾尔自治区人民医院血管外科2009年2月-2014年6月共11例破裂腹主动脉瘤患者的临床资料.其中男性9例,女性2例;年龄69 ~ 88岁,平均76岁.动脉粥样硬化性腹主动脉瘤7例,腹主动脉假性动脉瘤2例,感染性腹主动脉瘤2例.11例术前均完成CT动脉造影检查,急诊行腔内修复术,术中使用长鞘联合大球囊阻断技术.结果 术中无患者死亡.术后1例患者出现造影剂肾病;1例出现腹腔间隔室综合征,均在1周后死亡.随访期间,1例出现Ⅰ型内漏,再次行腔内治疗;1例假性动脉瘤复发再次破裂,放弃治疗.结论 长鞘联合大球囊阻断技术在破裂腹主动脉瘤腔内治疗是安全有效的治疗方式.  相似文献   
54.
There were controversial results between obesity‐associated markers and semen quality. In this study, we investigated the correlations between age, obesity‐associated markers including body mass index (BMI), waist‐to‐hip ratio (WHR), waist‐to‐height ratio (WHtR) and waist circumference (WC), the combination of age and obesity‐associated markers, semen parameters and serum reproductive hormone levels in 1231 subfertile men. The results showed that BMI, WC, WHR and WHtR were positively related to age, and there were also positive relations between BMI, WHR, WC and WHtR and between sperm concentration (SC), total sperm count (TSC), progressive motility (PR), sperm motility and per cent of normal sperm morphology (NSM). However, age, each of obesity‐associated markers and the combination of obesity‐associated markers and age were unrelated to any of semen parameters including total normal‐progressively motile sperm count (TNPMS). Age, BMI, WHR, WC and WHtR were negatively related to serum testosterone and SHBG levels. However, only serum LH and FSH levels were negatively related to sperm concentration, NSM and sperm motility. In a conclusion, although age and obesity have significant impacts on reproductive hormones such as testosterone, SHBG and oestradiol, semen parameters related to FSH and LH could not be influenced, indicating that obesity‐associated markers could not predict male semen quality.  相似文献   
55.
目的总结基于KTQ的人文关怀护理在CCU病房中的实践经验。方法将80例患者按入住时间分为常规护理组和人文关怀组各40例。常规护理组按常规实施护理,人文关怀组运用KTQ的管理模式,找出引起CCU患者焦虑的主要问题,实施人文关怀护理。结果通过人文关怀护理的实施,CCU患者焦虑明显下降,舒适度提高,护士满意度提高。结论基于KTQ管理模式的人文关怀对最大程度地减少CCU患者焦虑和不安心理有着重要意义。  相似文献   
56.
Only occupying about 1%–5% of total testicular cells, the adult Leydig cell (ALC) is a unique endocrine cell that produces androgens. Rat Leydig cells regenerate after these cells in the testis are eliminated with ethane dimethane sulfonate (EDS). In this study, we have characterized Leydig cell regeneration and messenger ribonucleic acids (mRNA) profiles of EDS treated rat testes. Serum testosterone, testicular gene profiling and some steroidogenesis-related proteins were analyzed at 7, 21, 35 and 90 days after EDS treatment. Testicular testosterone levels declined to undetectable levels until 7 days after treatment and then started to recover. Seven days after treatment, 81 mRNAs were down-regulated greater than or equal to two-fold, with 48 becoming undetectable. These genes increased their expression 21 days and completely returned to normal levels 90 days after treatment. The undetectable genes include steroidogenic pathway proteins: steroidogenic acute regulatory protein, Scarb1, Cyp11a1, Cyp17a1, Hsd3b1, Cyp1b1 and Cyp2a1. Seven days after treatment, there were 89 mRNAs up-regulated two-fold or more including Pkib. These up-regulated mRNAs returned to normal 90 days after treatment. Cyp2a1 did not start to recover until 35 days after treatment, indicating that this gene is only expressed in ALCs not in the precursor cells. Quantitative polymerase chain reaction, western blotting and semi-quantitative immunohistochemical staining using tissue array confirmed the changes of several randomly picked genes and their proteins.  相似文献   
57.
Semen samples were collected from 1213 fertile men whose partners had a time-to-pregnancy (TTP) ≤12 months in Guangdong Province in Southern China, and semen parameters including semen volume, sperm concentration, total counts, motility, and morphology were evaluated according to the World Health Organization (WHO) 2010 guideline. All semen parameters analyzed were normal in ~62.2% of the total samples, whereas ~37.8% showed at least one of the semen parameters below normal threshold values. The fifth centiles (with 95% confidence intervals) were 1.3 (1.2–1.5) ml for semen volume, 20 × 106 (18×106–20×106) ml−1 for sperm concentration, 40 × 106 (38×106–44×106) per ejaculate for total sperm counts, 48% (47%–53%) for vitality, 39% (36%–43%) for total motility, 25% (23%–27%) for sperm progressive motility, 5.0% (4%–5%) for normal morphology. The pH values ranged from 7.2 to 8.0 with the mean ± standard deviation at 7.32 ± 0.17. No effects of age and body mass index were found on semen parameters. Occupation, smoking and alcohol abuse, varicocele appeared to decrease semen quality. Sperm concentration, but not sperm morphology, is positively correlated with TTP, whereas vitality is negatively correlated with TTP. Our study provides the latest reference values for the semen parameters of Chinese fertile men in Guangdong Province, which are close to those described in the new WHO guidelines (5th Edition).  相似文献   
58.
OBJECTIVE: To investigate the relationship between plasma levels of fibrinogen, the-beta455 G/A fibrinogen gene polymorphism and the severity of periodontal inflammation and to explore the possible role of fibrinogen in the association of periodontitis with coronary heart disease (CHD). METHODS: A total of 121 patients with moderate to severe periodontitis and periodontally healthy and gingivitis controls were enrolled in the study. Peripheral blood samples were collected and the plasma fibrinogen levels were determined by the clotting method of Clauss. Polymerase chain reaction and restriction fragment length polymorphism analysis with Hae III were used to examine the -beta455 G/A fibrinogen gene polymorphism. RESULTS: Fibrinogen levels were significantly higher in moderately or severely chronic periodontitis patients [(3.45 +/- 0.68) g/L] than periodontally healthy and gingivitis controls [(2.47 +/- 0.42) g/L, P < 0.001]. The carrier status of the A allele at position -455 in the beta fibrinogen gene was associated with elevated fibrinogen levels and the frequency of the-A455 allele in the beta fibrinogen gene in the patient group was significantly higher than in the control group (P = 0.032). Carriers of the -A455 allele were about 3-fold more likely to have moderate or severe periodontitis as compare to individuals without the -A455 allele( OR = 3. =135, P= 0.008). CONCLUSIONS: Fg-beta455 G/A polymorphism may contribute to the elevated plasma fibrinogen levels and put individuals at higher risk of having severe periodontitis. As the independent risk factor of CHD, fibrinogen levels and Fg-beta455 G/A polymorphism may play a role in the pathogenesis of periodontitis.  相似文献   
59.
PBL是一种以学生为中心,以问题为导向,围绕病例进行的讨论式的全新教学模式。病案作为学生学习的焦点、讨论的框架在PBL的教学中起着至关重要的作用。本文从PBL教案的作用、使用、特点和撰写步骤等几个方面具体阐述了如何为PBL准备一个好的病案。  相似文献   
60.
目的:探讨颌面部神经内分泌癌的诊断和治疗特点。方法:2名面部原发神经内分泌癌患者和3名面部转移性神经内分泌癌患者,经手术治疗并在术后随访最长达30个月,CT、MRI和PET检查用于帮助诊断。结果:2名面部原发神经内分泌癌患者中,1名任术后出现局部复发并经历第二次手术,另一名患者术后接受放疗,随访20个月未见复发。3名转移性神经内分泌癌患者中,1名住术后4个月死亡。结论:颌面部神经内分泌癌,是一种少见的高度恶性的肿瘤,原发神经内分泌癌术后易复发,CT、MRI和PET检查有助于诊断。  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