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   89463篇
  免费   8823篇
  国内免费   7289篇
耳鼻咽喉   650篇
儿科学   826篇
妇产科学   985篇
基础医学   10678篇
口腔科学   1598篇
临床医学   12967篇
内科学   13129篇
皮肤病学   722篇
神经病学   5294篇
特种医学   3160篇
外国民族医学   56篇
外科学   8286篇
综合类   15332篇
现状与发展   22篇
一般理论   13篇
预防医学   5803篇
眼科学   2942篇
药学   9241篇
  102篇
中国医学   5820篇
肿瘤学   7949篇
  2024年   313篇
  2023年   1522篇
  2022年   4288篇
  2021年   5170篇
  2020年   3933篇
  2019年   3202篇
  2018年   3427篇
  2017年   2872篇
  2016年   2822篇
  2015年   4291篇
  2014年   5277篇
  2013年   4462篇
  2012年   6562篇
  2011年   7604篇
  2010年   4567篇
  2009年   3581篇
  2008年   4585篇
  2007年   4450篇
  2006年   4624篇
  2005年   4650篇
  2004年   2738篇
  2003年   2662篇
  2002年   2220篇
  2001年   1935篇
  2000年   2057篇
  1999年   2160篇
  1998年   1443篇
  1997年   1366篇
  1996年   1099篇
  1995年   1017篇
  1994年   842篇
  1993年   535篇
  1992年   601篇
  1991年   509篇
  1990年   466篇
  1989年   420篇
  1988年   347篇
  1987年   296篇
  1986年   228篇
  1985年   178篇
  1984年   81篇
  1983年   50篇
  1982年   41篇
  1981年   36篇
  1980年   24篇
  1979年   21篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的探讨多系统萎缩(MSA)的临床特征与疾病进展的特点。方法回顾性分析28例拟诊MSA患者的临床资料;用代表日常生活活动能力(ADL)的3个重要事件(辅助行走、依靠轮椅、卧床状态)对疾病进展进行评估;通过Kaplan-Meier曲线分析各亚组间的差异。结果3个以上系统受累26例(92.9%),普遍存在自主神经功能障碍。从起病进展为临床MSA平均2年;进展为辅助行走、依靠轮椅和卧床状态分别为3年、5年、7年。运动和自主神经系统同时受累的患者起病3年内疾病进展的危险性明显增加(P<0.01)。结论MSA是一种多系统受累的慢性进展性疾病,从起始症状到同时出现运动和自主神经功能障碍的间隔时间能够预测MSA功能衰退的进展。  相似文献   
992.
边防海岛战士心理健康状况及人格特征与应对方式的研究   总被引:3,自引:2,他引:1  
目的了解边防海岛战士的心理健康状况,人格特征及应对方式的关系。方法采用症状自评量表(SCL-90)、艾森克个性问卷(EPQ)和简易应对方式问卷对960名边防海岛战士进行心理测试,了解他们心理健康状况,人格特征和应对方式特点及其影响因素。结果(1)边防海岛战士SCL-90各因子分均显著高于军人常模;(2)边防海岛战士应对方式与心理健康状况密切相关,积极应对方式与SCL-90某些因子相关,消极应对方式与SCL-90各因子均呈显著正相关(P<0.01);(3)边防海岛战士在面对应激时所采取的应对方式与人格特征密切相关,消极应对方式与人格问卷中的P分(精神质)和N分(神经质)有显著或高度显著正相关(P<0.01),积极应对方式与人格问卷中的P分(精神质)呈负相关,和E分(内外向)呈正相关。结论边防海岛战士心理健康状况差于军人总体水平,人格特征及应对方式对心理健康水平有较大影响。  相似文献   
993.
应对方式的干预对边防海岛军人心理健康的影响   总被引:2,自引:2,他引:0  
目的通过改变边防海岛军人的应对方式来提高他们的心理健康水平,提高部队的战斗力。方法运用多种形式组合的综合心理干预对边防海岛军人的应对方式进行干预,选用症状自评量表(SCL-90)、简易应对方式量表对边防海岛军人行心理测量。结果采取综合心理干预的边防海岛军人的症状自评量表(SCL-90)各项因子分均低于未采取综合心理干预的边防海岛军人(P<0.01),与未采取综合心理干预的边防海岛军人相比较,采取综合心理干预的边防海岛军人更多地采取积极的应对方式(P<0.01)。结论通过综合心理干预,让边防海岛军人更多地采取积极的应对方式对待生活和对抗应激,对提高和维护边防海岛军人的心理健康水平,确保部队的战斗力具有积极的意义。  相似文献   
994.
目的探讨疏肝健脾法对肝癌患者肝动脉化疗栓塞后免疫功能的影响。方法103例中晚期原发性肝癌患者随机分为治疗组(n=52)及对照组(n=51)。两组患者介入治疗后均予西药常规护肝治疗及对症处理,治疗组在介入治疗前7 d开始服用疏肝健脾中药,介入治疗后随症加减,对照组单纯行肝动脉化疗栓塞。两组患者分别在第1次介入前、第2次介入后4周检查T淋巴细胞亚群。结果第1次介入前治疗组和对照组的NK细胞、CD3、CD4、CD4/CD8比值差异无显著性,P均>0.05。第2次介入后4周对照组的NK细胞、CD3、CD4、CD4/CD8比值均下降;而治疗组的NK细胞、CD3、CD4、CD4/CD8比值均升高,与治疗前比较有统计学意义,P均<0.05。结论疏肝健脾法可提高肝癌患者TACE后的免疫功能。  相似文献   
995.
PurposeTo evaluate the potential causal associations between type 2 diabetes and fasting glucose and HbA1c levels and the risk of primary open-angle glaucoma (POAG) in European and East Asian populations.MethodsWe selected genetic variants (P < 5 × 10−8) for type 2 diabetes (898,130 Europeans; 433,540 East Asians), fasting glucose, and HbA1c (196,991 Europeans; 36,584 East Asians) from three meta-analyses of genome-wide association studies (GWAS). The GWAS for POAG provided summary statistics (192,702 Europeans; 46,523 East Asians). Mendelian randomization (MR) analysis was accomplished using the inverse variance–weighted method, weighted-median method, MR Egger method, and MR-Pleiotropy RESidual Sum and Outlier test.ResultsGenetically predicted type 2 diabetes was potentially positively associated with POAG in the European ancestry (body mass index [BMI]–unadjusted: odds ratio [OR] = 1.07, 95% confidence interval [CI], 1.01–1.14, P = 0.028; BMI-adjusted: OR = 1.07, 95% CI, 1.01–1.15, P = 0.035), but not in the East Asian ancestry (BMI-unadjusted: OR = 1.01, 95% CI, 0.95–1.06, P = 0.866; BMI-adjusted: OR = 1.00, 95% CI, 0.94–1.05, P = 0.882). There was no evidence to support a causal association of fasting glucose (European: OR = 1.19, P = 0.157; East Asian: OR = 0.94, P = 0.715) and HbA1c (European: OR = 1.27, P = 0.178; East Asian: OR = 0.85, P = 0.508) levels with POAG.ConclusionsThe causal effect of type 2 diabetes on the risk of POAG is different in European and East Asian populations. The point estimates of fasting glucose and Hb1Ac with POAG are large but not statistically significant, which prompts the question of statistical power.  相似文献   
996.
β654-thalassemia is a prominent Chinese subtype of β-thalassemia, representing 17% of all cases of β-thalassemia in China. The molecular mechanism underlying this subtype involves the IVS-2-654 C→T mutation leading to aberrant β-globin RNA splicing. This results in an additional 73-nucleotide exon between exons 2 and 3 and leads to a severe thalassemia syndrome. Herein, we explored a CRISPR/Cas9 genome editing approach to eliminate the additional 73-nucleotide by targeting both the IVS-2-654 C→T and a cryptic acceptor splice site at IVS-2-579 in order to correct aberrant β-globin RNA splicing and ameliorate the clinical β-thalassemia syndrome in β654 mice. Gene-edited mice were generated by microinjection of sgRNA and Cas9 mRNA into one-cell embryos of β654 or control mice: 83.3% of live-born mice were gene-edited, 70% of which produced correctly spliced RNA. No off-target events were observed. The clinical symptoms, including hematologic parameters and tissue pathology of all of the edited β654 founders and their offspring were significantly improved compared to those of the non-edited β654 mice, consistent with the restoration of wild-type β-globin RNA expression. Notably, the survival rate of gene-edited heterozygous β654 mice increased significantly, and live-born homozygous β654 mice were observed. Our study demonstrated a new and effective gene-editing approach that may provide groundwork for the exploration of β654-thalassemia therapy in the future.  相似文献   
997.
Hierarchically porous MIL-101(Cr) (H-MIL-101(Cr)) with meso/macro-pores was directly prepared via nanofusion progress by using butyric acid as a modulating agent. In the methyl orange (MO) adsorption experiments, H-MIL-101(Cr) showed a high adsorption capability of 369.8 mg g−1, which was 1.52-fold greater than that of pristine MIL-101(Cr) (P-MIL-101(Cr)). While in the oxidation reaction of indene and 1-dodecene tests, H-MIL-101(Cr) presented much higher catalytic efficiency, with turnover frequency (TOF) values of 0.7242 mmol g−1 min−1 and 0.1492 mmol g−1 min−1, respectively, which were 28% and 34% greater than that in the case of P-MIL-101(Cr). Thus, compared with P-MIL-101(Cr), H-MIL-101(Cr) exhibited better removal efficiency and higher levels of activity in the oxidation reactions of indene and 1-dodecene. The unique structure of H-MIL-101(Cr) also contributed to its superior performance in these processes.  相似文献   
998.
Porcine epidemic diarrhea (PED), characterized by diarrhea, vomiting, and dehydration, is an acute enteric infectious disease of pigs. The disease is caused by porcine epidemic diarrhea virus (PEDV), which infects the intestinal mucosal surface. Therefore, mucosal immunization through the oral route is an effective method of immunization. Lactic acid bacteria, which are acid resistant and bile-salt resistant and improve mucosal immunity, are ideal carriers for oral vaccines. The S1 glycoprotein of PEDV mediates binding of the virus with cell receptors and induces neutralizing antibodies against the virus. Therefore, we reversely screened the recombinant strain pPG-SD-S1/Δupp ATCC 393 expressing PEDV S1 glycoprotein by Lactobacillus casei deficient in upp genotype (Δupp ATCC 393). Mice were orally immunized three times with the recombinant bacteria that had been identified for expression, and the changes of anti-PEDV IgG and secreted immunoglobulin A levels were observed over 70 days. The results indicated that the antibody levels notably increased after oral administration of recombinant bacteria. The detection of extracellular cytokines on the 42nd day after immunization indicated high levels of humoral and cellular immune responses in mice. The above results demonstrate that pPG-SD-S1/Δupp ATCC 393 has great potential as an oral vaccine against PEDV.  相似文献   
999.
1000.
Steel is one of the most important industrial materials, which mainly comes from the smelting of iron ore. In view of the huge steel consumption every year, the exploitation of vast reserves of siderite ores is significant for improving the self-sufficiency rate of iron ore resources and ensuring the strategic security of the iron and steel industries. This paper investigated the influence of temperature, time, and other parameters on the magnetic properties of roasted siderite ores using the method of suspended roasting and analyzed the washability of roasted ores under weak-magnetic-field conditions using the magnetic separation tube experiment. The findings of the study explained the iron phase transformation process, i.e., FeCO3 was transformed into Fe3O4 by suspension magnetization roasting. Furthermore, the saturation magnetization of the roasted ore increased in due time at a constant temperature range of 550–750 °C and a roasting time of less than 5 s. It also increased with increasing temperature and constant time. The roasted ore achieved the best magnetic characteristics after roasting at 750 °C for 5 s. After low-intensity magnetic separation, the iron grade of the concentrate changed to 55.12%, with a recovery rate of 90.34%. The study results provide a reference for the development and application of siderite suspension magnetization roasting technology.  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