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   128121篇
  免费   12232篇
  国内免费   8190篇
耳鼻咽喉   911篇
儿科学   1801篇
妇产科学   1839篇
基础医学   14007篇
口腔科学   2478篇
临床医学   16891篇
内科学   18541篇
皮肤病学   1369篇
神经病学   6233篇
特种医学   4237篇
外国民族医学   51篇
外科学   10816篇
综合类   23325篇
现状与发展   31篇
一般理论   17篇
预防医学   10317篇
眼科学   3260篇
药学   14296篇
  138篇
中国医学   8045篇
肿瘤学   9940篇
  2024年   502篇
  2023年   1911篇
  2022年   4615篇
  2021年   6022篇
  2020年   4749篇
  2019年   3900篇
  2018年   4083篇
  2017年   3966篇
  2016年   3585篇
  2015年   5557篇
  2014年   6931篇
  2013年   6927篇
  2012年   10145篇
  2011年   10742篇
  2010年   7605篇
  2009年   6244篇
  2008年   7615篇
  2007年   7379篇
  2006年   6786篇
  2005年   6339篇
  2004年   4536篇
  2003年   4134篇
  2002年   3655篇
  2001年   2872篇
  2000年   2830篇
  1999年   2631篇
  1998年   1638篇
  1997年   1607篇
  1996年   1245篇
  1995年   1203篇
  1994年   986篇
  1993年   592篇
  1992年   728篇
  1991年   680篇
  1990年   575篇
  1989年   521篇
  1988年   409篇
  1987年   429篇
  1986年   334篇
  1985年   265篇
  1984年   181篇
  1983年   137篇
  1982年   91篇
  1981年   77篇
  1980年   67篇
  1979年   69篇
  1978年   43篇
  1973年   46篇
  1972年   39篇
  1970年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
应用放射性配基结合分析法,检测了40例结直肠癌及部分癌旁正常粘膜组织中的雄激素受体(AndrogenReceptor,AR),同时分析了AR水平与临床病理学变化的关系。证实结直肠癌AR数目(33.7±23.3fmol/mg蛋白)明显低于癌旁5cm以外粘膜(53.9±32.4fmol/mg蛋白),P<0.01,而其亲和力则无变化;结直肠癌时AR数目变化与女性、直肠癌、高分化癌及早期癌关系密切。提示AR与结直肠癌关系密切,本实验为临床上结直肠癌的诊断及内分泌治疗提供了初步资料。  相似文献   
92.
对60例胃癌进行了粘液组织化学和癌胚抗原免疫组织化学研究。结果表明:胃癌发病率肠型和胃肠混合型占多数。60例胃癌中含大肠型粘液者占50例,而单纯含胃型粘液为极少数。癌胚抗原分布方式,肠型胃癌与胃肠混合型胃癌比较无显著差异性(P>0.05)。癌胚抗原的阳性率,胃肠混合型胃癌高于肠型胃癌,两者之间有非常显著差别(P<0.01)。认为选用能显示硫粘蛋白和氧乙酰基唾液酸粘蛋白的粘液组织化学方法,作为胃癌组织分型和确定胃粘膜肠化性质,对癌前病变诊断有一定价值。  相似文献   
93.
Freshly derived murine CD4+ T cells are divided into naive and memory cells based on the expression of CD45 isoforms. Cross-linking the T cell receptor CD3 complex either by plastic-bound anti-CD3 antibodies or the antibody presented on non-lymphoid Fc gamma receptor type II-positive Chinese hamster ovary cells in absence of competent antigen-presenting cells fails to activate naive cells to either secrete cytokines or to proliferate. In contrast, memory cells secrete their characteristic cytokines [interleukin (IL) 2, IL4, and interferon-gamma] and show significant proliferation to this stimulus. IL 1 however, is required for their optimal clonal expansion. Differential expression of IL 1 receptor mRNA in memory cells also correlate with their responsiveness to IL 1. Thus, these data reveal a basic difference in the requirements for activation of naive and memory CD4+ T cells.  相似文献   
94.
95.
BACKGROUND AND PURPOSE: The potential risk of prolongation of treatment time in cervical cancer has been reported for many low-dose rate (LDR) studies, with an estimated loss of local control ranging from 0.3 to 1.6% per day of treatment prolongation. Since the treatment schedule for fractionated high-dose rate intracavitary brachytherapy (HDRICB) is not directly comparable with that for low-dose rate studies, this report aims to evaluate the adverse effect of treatment prolongation specifically for cervical cancer treated with HDRICB. MATERIAL AND METHODS: From September 1992 to December 1997, 257 patients diagnosed with uterine cervical cancer (35 Ib, 26 IIa, 122 IIb, 10 IIIa, 57 IIIb, 7 IVa), who underwent external radiotherapy combined with between two and four courses of HDRICB and a minimum of 3 years of follow-up (median 57 months), were analyzed. Treatment consisted of irradiation of the whole pelvis with 44-45 Gy consisting of 22-25 fractions by 5 weeks, with the dose boosted to 54-58 Gy (with central shielding) for patients diagnosed as FIGO stage IIb-IVa bilateral parametrial disease. HDRICB was performed using an Ir-192 remote afterloading technique at 1-week intervals. The standard prescribed dose for each course of HDRICB was 7.2 Gy to point A for three insertions (before July 1995), or 6.0 Gy to point A for four insertions (after July 1995). Total prescribed point A doses (external beam radiotherapy+HDRICB) ranged from 58 to 71.6 Gy (median, 65.6 Gy) for stage IB-IIA, while analogous dosage for larger lesions (stage IIb-IVa) ranged from 59 to 75.6 Gy (median, 65.6 Gy). Kaplan-Meier and multivariate analyses were used to test the effect of treatment time on pelvic control rate (PCR) and cause-specific survival (CSS) at 5 years. RESULTS: Median treatment time was 63 days. For all stages of disease, the 5-year CSS and PCR were significantly different comparing treatment times of less than and greater than or equal to 63 days [83% and 65% (P=0.004], 93% and 83% (P=0.02), respectively]. These associations were also significant for stage Ib/IIa [97% and 79% (P=0.01), and 100% and 87% (P=0.02), respectively), but not for stage IIb [75% and 72% (P=0.79), and 93% and 87% (P=0.83), respectively] or stage III [66% and 49% (P=0.2), and 83% and 72% (P=0.21), respectively]. Multivariate analysis identified three prognostic factors for CSS, stage (P<0.001), tumor response to external RT (P=0.001), and overall treatment time (OTT; P=0.006). Prognostic factors for pelvic failure were stage (P<0.001), tumor response to external RT (P=0.001), and OTT (P=0.03). Prolongation of treatment time resulted in a daily decrease in pelvic control rate of 0.67% overall, and 0.43% for stage Ib-IIa, 0.57% for stage IIb, and 0.73% for stage III patients. CONCLUSION: Analysis of the data from the current study demonstrates that the adverse effect of treatment prolongation was observed later in the treatment course for the high-dose rate (HDR) series compared to the LDR analog, however, treatment-time prolongation still negatively influenced the cause-specific survival and pelvic control rate for both dosage groups.  相似文献   
96.
王伟 《护理研究》2006,20(5):1297-1297
喉镜是气管插管的必备工具,为在不影响其使用功能的同时避免交叉感染,我科使用避孕套保护喉镜,取得了良好效果。现介绍如下。  相似文献   
97.
目的应用超声多普勒方法评价冠心病患者的左室整体舒张功能及舒张功能障碍的发生率,探讨舒张功能障碍在冠心病无创诊断中的价值。方法对入选病人行常规检查,同时进行二尖瓣血流频谱、肺静脉血流频谱及二尖瓣环组织多普勒检查,对比临床标准与舒张功能障碍标准对冠心病的诊断率。结果舒张功能障碍标准对冠心病的检出率显著高于临床标准。结论舒张功能检查可作为冠心病诊断的初筛检查。  相似文献   
98.
INTRODUCTION: Levosimendan is an inodilatory drug with hemodynamic effects in patients with decompensated chronic heart failure. AIM: Short-term (one month) evaluation of clinical, hemodynamic and neurohormonal changes in patients with decompensated chronic heart failure undergoing levosimendan therapy. METHODS: Twenty-six (21 male) consecutive patients were studied, corresponding to 32 levosimendan administrations (bolus + 24h infusion), aged 56.7+/-13.0 years, with decompensated chronic heart failure, in NYHA functional class III-IV (78.1% in class IV), and cardiac index (CI) <2.5 l/min/m2. Clinical (NYHA class), non-invasive hemodynamic (echocardiography) and neurohormonal (Elecsys ECLIA NT-ProBNP) evaluations were performed before levosimendan administration and on days 1, 4, 10 and 30. RESULTS: 1) Until day 10, there was a progressive decrease in NT-ProBNP values and weight (p<0.001), with an increase in CI (p<0.001); 2) NYHA functional class improved progressively, with 76% of the patients in NYHA class II at day 30; 3) NT-ProBNP values at day 1 correlated inversely (r=-0.414; p=0.024) with CI at day 4; and 4) the absolute decrease in NT-ProBNP values at day 4 (relative to baseline values) correlated with weight loss at day 4 (r=0.495, p=0.005), day 10 (r=0.424, p=0.031) and day 30 (r=0.486, p=0.030). CONCLUSION: Levosimendan therapy in patients with decompensated chronic heart failure contributes to progressive NYHA class improvement. The variations seen in NYHA class and hemodynamics was reflected in changes in NT-ProBNP.  相似文献   
99.
Background  High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data. Methods and Results  The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients (mean SD, 0.005 cm−1 vs 0.011 cm−1; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP. Conclusion  This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum of patient BMI values and significantly improves attenuation-corrected perfusion images.  相似文献   
100.
胫骨结节骨骺炎是由于股四头肌肌腱对胫骨结节的过度牵拉造成的骨骺疾病,在刚从事运动训练的青少年及刚人体育院校学习的新生中发病率较高,尤其多见于田径、篮球、排球等项目专选的学生。笔者自2000年~2003年中,共收治了16例该病患者,均获满意疗效,现介绍如下。  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