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   7153篇
  免费   340篇
  国内免费   55篇
耳鼻咽喉   43篇
儿科学   117篇
妇产科学   85篇
基础医学   1343篇
口腔科学   96篇
临床医学   596篇
内科学   1120篇
皮肤病学   168篇
神经病学   882篇
特种医学   247篇
外科学   945篇
综合类   41篇
一般理论   2篇
预防医学   358篇
眼科学   239篇
药学   635篇
中国医学   10篇
肿瘤学   621篇
  2023年   24篇
  2022年   57篇
  2021年   97篇
  2020年   51篇
  2019年   87篇
  2018年   83篇
  2017年   61篇
  2016年   90篇
  2015年   131篇
  2014年   157篇
  2013年   271篇
  2012年   386篇
  2011年   421篇
  2010年   272篇
  2009年   257篇
  2008年   453篇
  2007年   527篇
  2006年   490篇
  2005年   566篇
  2004年   473篇
  2003年   526篇
  2002年   475篇
  2001年   79篇
  2000年   62篇
  1999年   94篇
  1998年   135篇
  1997年   92篇
  1996年   80篇
  1995年   66篇
  1994年   62篇
  1993年   75篇
  1992年   35篇
  1991年   60篇
  1990年   38篇
  1989年   43篇
  1988年   23篇
  1987年   23篇
  1986年   24篇
  1985年   22篇
  1984年   24篇
  1983年   26篇
  1982年   33篇
  1981年   31篇
  1980年   28篇
  1978年   21篇
  1977年   29篇
  1976年   19篇
  1975年   19篇
  1974年   21篇
  1971年   18篇
排序方式: 共有7548条查询结果,搜索用时 0 毫秒
71.
72.
Reversible histone methylation has emerged in the last few years as an important mechanism of epigenetic regulation. Histone methyltransferases and demethylases have been identified as contributing factors in the development of several diseases, especially cancer. Therefore, they have been postulated to be new drug targets with high therapeutic potential. Here, we review histone demethylases with a special focus on their potential role in oncology drug discovery. We present an overview over the different classes of enzymes, their biochemistry, selected data on their role in physiology and already available inhibitors.  相似文献   
73.

In this quasi‐experimental pilot study, women who were returning to work within 6 months after the birth of a first baby were assigned to participate in a control group (n = 13) or a six‐session small group intervention (n = 18). The content of the group intervention was developed based on a stress and coping framework (Lazarus & Folkman, 1984).”; The experimental and control groups were surveyed at 2 months after their return to employment and on their baby's first birthday on measures of well‐being in marriage, work, and parenting. Repeated measures analysis of covariance was used to examine differences over time between the experimental and control group with length of maternity leave and number of hours worked as covariates. Participants in the intervention reported increasing levels of marital satisfaction over time, whereas the control group experienced a decline in marital satisfaction over time (p = .04). Implications for practice and research are presented.  相似文献   
74.
The effects of industrial noise on resting heart rate and blood pressure were studied in 3 105 blue-collar workers. Heart rate and blood pressure were measured in different workers at various times during the workday. After controlling for several possible confounders, we found that resting heart rate in females was associated positively with noise intensity (p = .036) and with time of day (p = .054). In males, resting heart rate was associated with noise intensity; however, such association was related to time of day (p = .046). No such associations were found for blood pressure in either sex. We plotted the mean resting heart rate by time of day for workers exposed to high [≥ 80 db(A)] and low noise, and no difference was evident with respect to morning heart rate in either sex. After 4 h of noise exposure for males (and less time for females), individuals who were exposed to high noise had higher heart rates; however, in females this was not observed at the end of the workday. Thus, recurrent daily exposure to high noise at work has an acute, though not residual, effect on resting heart rate.  相似文献   
75.
目的: 植体周围一定程度的骨丧失可能会给牙种植治疗的美观效果带来不利影响。这种情况可能更容易影响软组织水平(Tissue-Level, TL)设计,因此,当强调形态的美观自然性时,骨组织水平(Bone-Level, BL)设计可能更有优势。除了植体的设计,牙龈生物型也被认为是维持牙槽骨稳定的重要因素。本研究拟针对具有不同牙龈生物型的患者,在其美学区域行软组织水平和骨水平牙种植治疗,探究其骨丧失的程度。材料和方法: 对41位患者行20个TL和22个BL种植治疗,术后即刻、术后随访对这42个位点行口内影像学检查;运用计算机技术行牙槽骨高度测量分析;运用TRAN法鉴定患者的牙龈生物型。结果: TL组平均4.9年的存留期里,厚龈型的12颗植体周围平均骨丧失0.21mm(SD:0.43mm);薄龈型的8颗植体周围平均骨丧失0.05mm(SD:0.47mm;P=0.31)。BL组平均1.9年的存留期里,厚龈型的14颗植体周围骨丧失为-0.03mm(SD:0.38mm),薄龈型的8颗植体周围骨丧失为+0.09mm(SD:0.32mm;P=0.84)。结论: 分析得到的数据发现,牙槽骨高度的变化与种植设计或是牙龈生物型并无直接相关性。然而在选择种植设计之前,评价软组织的厚度是有利的,其中BL种植设计更能获得自然的外形。为实现以上评价目的,TRAN法是最快速、简易的方法。  相似文献   
76.
77.
PURPOSE: To evaluate the feasibility and efficacy of the local application of a replication-defective adenovirus construct for the expression of the antiinflammatory protein I kappa B alpha, inhibitor of nuclear factor kappa B (NF-kappa B), to reduce neointimal formation after stent placement. MATERIALS AND METHODS: Nitinol stents were implanted in the iliac arteries of hypercholesterolemic rabbits, followed by balloon dilation (30 seconds at 6 atm). Local adenovirus-mediated transfer of I kappa B alpha (3 mL of 10(9) plaque-forming units per milliliter at 6 atm) was performed and compared with three control groups: stent alone, stent plus local delivery of phosphate-buffered saline (PBS) (3 mL at 6 atm), and stent plus local delivery of control adenovirus coding for green fluorescent protein (GFP) (3 mL of 10(9) plaque-forming units per milliliter at 6 atm). A multichannel balloon was used for local drug delivery and balloon dilation. Animals were sacrificed 1 or 4 weeks after treatment. Effective transfection was demonstrated with immunofluorescence staining. Angiographic patency and luminal diameter were evaluated at quantitative angiography. Luminal and neointimal areas were measured on surface-stained ground sections with methylmethacrylate embedding and the cutting-grinding technique. RESULTS: All vessels with stents were patent at angiography. Neointimal area was negligible in all groups 1 week after stent placement (range, 0.42-0.52 mm(2); P =.44; analysis of variance). Neointimal formation was demonstrated in all groups 4 weeks after implantation but was significantly reduced with I kappa B alpha treatment compared with treatment with stent alone (by 22%, from 2.80 mm(2) +/- 0.20 to 2.28 mm(2) +/- 0.14, P =.05), stent plus PBS (by 43%, from 3.26 mm(2) +/- 0.25 to 2.28 mm(2) +/- 0.14, P =.005), and stent plus GFP (by 53%, from 2.32 mm(2) +/- 0.19 to 1.51 mm(2) +/- 0.08, P <.005). CONCLUSION: Local adenovirus-mediated I kappa B alpha gene transfer has the potential to reduce intimal hyperplasia after stent placement.  相似文献   
78.
PURPOSE: The purpose of this work was to compare nonfunctional and functional spiral CT in the tumor (T) staging of laryngeal and hypopharyngeal tumors and to correlate the CT results with microlaryngoscopy and postoperative pathology. METHOD: Twenty-six patients (3 women, 23 men) with clinically suspected laryngeal and hypopharyngeal tumors underwent both nonfunctional CT during quiet breathing and functional spiral CT during either a modified Valsalva (n = 19) or E phonation (n = 7) maneuver. CT slice thickness was 3 mm, table feed was 3 mm, and 40-80 ml of intravenous contrast material was administered at a flow of 1.5 ml/s. T stages as determined by nonfunctional and functional CT were compared and correlated with postoperative pathology or microlaryngoscopy. RESULTS: The T stages determined with functional CT were better correlated with postoperative pathology (rS = 0.88, p = 0.001) and microlaryngoscopy (rS = 0.77, p = 0.008) than T stages determined with nonfunctional CT (rS = 0.80, p = 0.001; and rS = 0.51, p = 0.13, respectively). Twelve of 26 patients (46%) had a lower T stage on functional than on nonfunctional CT. In 14 of 26 patients (54%), the T stage was identical with both modalities. In no patients was the T stage increased by functional CT. CONCLUSION: Functional CT appears to be more accurate than nonfunctional CT in the T staging of laryngeal and hypopharyngeal carcinomas. Functional CT also results in lower T stages than nonfunctional CT in a substantial number of patients.  相似文献   
79.
Patients with trauma or medical illnesses transported to the hospital by ambulance have a frequent incidence of motion sickness. Because the administration of drugs in the ambulance is prohibited by law in Austria, the noninvasive Korean hand acupressure point at K-K9 may be an alternative against nausea and vomiting. We enrolled 100 geriatric patients with minor trauma, randomizing them into a K-K9 group and a sham acupressure group. We recorded visual analog scores (VAS) for nausea and for the patient's overall satisfaction with the treatment, hemodynamic variables, and peripheral vasoconstriction. In the K-K9 group, a significant (P < 0.01) increase in nausea was recorded in all cases: from VAS of 0 mm to 25 +/- 6 mm. A similarly significant (P < 0.01) increase was registered in the sham group: from VAS of 0 mm to 83 +/- 8 mm. However, at the time of arrival in the hospital, nausea scores were significantly different between the K-K9 group and the sham group (P < 0.01). Although all patients had been vasoconstricted at the emergency site before treatment, there was a significant difference (P < 0.01) between groups with regard to the number of vasoconstricted patients at the hospital (4 and 46 constricted and dilated, respectively, in the K-K9 group versus 48 and 2 constricted and dilated, respectively, in the sham group). On arrival in the hospital, a significant difference (P < 0.01) in heart rate was noted between the K-K9 group and the sham group (65 +/- 6 bpm versus 98 +/- 8 bpm). The patients' overall satisfaction with the provided care was significantly higher (P < 0.01) in the K-K9 group (19 +/- 9 mm VAS) than in the sham group (48 +/- 12 mm VAS). Neither group experienced a significant change in blood pressure. K-K9 stimulation was an effective and simple treatment for nausea during emergency care and significantly improved patient satisfaction. IMPLICATIONS: Korean hand acupressure at the K-K9 point was effective in reducing nausea and subjective symptoms of motion sickness in emergency trauma transport of patients at high risk of motion sickness.  相似文献   
80.
OBJECTIVE: To assess the efficacy and the tolerability of flutamide as adjuvant treatment after radical prostatectomy for locally advanced, lymph node-negative prostate cancer. METHODS: Men with locally advanced, lymph node-negative prostate cancer were randomized after radical prostatectomy to receive either flutamide 750mg daily or no adjuvant treatment. Recurrence-free and overall survival were the study end points. Recurrence was defined as a PSA value greater than 5ng/ml or two values greater than 2ng/ml more than three months apart with increasing tendency or three values greater than 1ng/ml more than three months apart with increasing tendency or any clinical recurrence. RESULTS: 309 patients (157 in the control arm and 152 in the flutamide arm) were eligible for efficacy analysis. The median follow-up was 6.1 years. Recurrence-free survival was better in the flutamide group ( P=0.0041), there was, however, no detectable difference in overall survival ( p=0.92 ). Moreover, there was a considerable toxicity reported in the flutamide group. CONCLUSION: Although having some effect on disease recurrence, adjuvant flutamide treatment does not improve median-term overall survival after radical prostatectomy for locally advanced, lymph node-negative prostate cancer.  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