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   6165篇
  免费   332篇
  国内免费   235篇
耳鼻咽喉   33篇
儿科学   78篇
妇产科学   18篇
基础医学   963篇
口腔科学   556篇
临床医学   363篇
内科学   682篇
皮肤病学   79篇
神经病学   310篇
特种医学   88篇
外科学   789篇
综合类   512篇
现状与发展   1篇
预防医学   271篇
眼科学   31篇
药学   1585篇
  4篇
中国医学   201篇
肿瘤学   168篇
  2023年   50篇
  2022年   153篇
  2021年   173篇
  2020年   152篇
  2019年   172篇
  2018年   193篇
  2017年   160篇
  2016年   155篇
  2015年   143篇
  2014年   435篇
  2013年   407篇
  2012年   372篇
  2011年   413篇
  2010年   349篇
  2009年   319篇
  2008年   276篇
  2007年   260篇
  2006年   259篇
  2005年   230篇
  2004年   202篇
  2003年   168篇
  2002年   164篇
  2001年   120篇
  2000年   86篇
  1999年   91篇
  1998年   79篇
  1997年   73篇
  1996年   75篇
  1995年   54篇
  1994年   48篇
  1993年   39篇
  1992年   41篇
  1991年   35篇
  1990年   40篇
  1989年   40篇
  1988年   32篇
  1987年   34篇
  1986年   27篇
  1985年   84篇
  1984年   86篇
  1983年   84篇
  1982年   77篇
  1981年   57篇
  1980年   51篇
  1979年   52篇
  1978年   28篇
  1977年   24篇
  1976年   21篇
  1975年   14篇
  1973年   15篇
排序方式: 共有6732条查询结果,搜索用时 0 毫秒
31.
32.
Hb F, Hb A2 and i-antigen expression were investigated in adulthood acute leukemias. The study of i-antigen expression by immuno-agglutination and immunofluorescence showed that it is preferentially increased among AML patients. A similar result was obtained for F-cell frequency which was often increased in AML, while it was normal in ALL. Hb A2 level was significantly lower in AML than in ALL. These differences between AML and ALL red cell patterns further suggest that the leukemic clone involves the erythroid lineage in AML but not in ALL.  相似文献   
33.
The potassium titanyl phosphate (KTP-532) laser has been applied to otologic surgery with a proven record of both safety and efficacy. The aim of this study was to demonstrate the use, safety, and advantages of laser dissection in the surgical treatment of acoustic neuromas. The authors' experience with 111 patients in whom laser surgery was used in acoustic neuroma is presented, with emphasis on surgical technique employed and facial nerve functional outcome. The method of laser dissection did not result in deleterious neurologic sequelae or laser-specific complications. In addition, laser dissection afforded certain advantages to traditional techniques, especially in larger tumors. The facial nerve functional outcome as assessed by the House-Brackmann grading system revealed that 90.2% of small tumors, 72.2% of medium tumors, and 75.0% of large tumors achieved satisfactory (grades I and II) functional results. These results compare favorably with the literature describing nonlaser dissection techniques. The observations and results reported in this article demonstrate the safety of the KTP-532 laser in the posterior cranial fossa, and specific advantages that this technology may offer to the surgical armamentarium of the neuro-otologist are outlined.  相似文献   
34.
简要论述目前磷酸二氢钾的各种制备方法 ,评价各种方法的优缺点。认为电解法制备磷酸二氢钾是有利的 ,该方法产物纯度高 ,对环境污染轻微 ,工艺流程短 ,对设备的腐蚀弱  相似文献   
35.
目的: 分析右雷佐生联合磷酸肌酸钠对蒽环类药物致乳腺癌患者心脏损伤的预防作用及安全性。方法:收集200例女性乳腺癌患者,随机分为对照组、A组、B组、C组,每组各50例。对照组给予标准剂量的AC或EC方案化疗,A组在对照组基础上给予注射用右雷佐生,B组在对照组基础上给予注射用磷酸肌酸钠,C组在对照组基础上给予右雷佐生及磷酸肌酸钠,3周为1个化疗周期。比较各组化疗后心脏损伤发生率,分析蒽环类药物致心脏毒性的危险因素,并观察化疗前及化疗3个周期后患者心电图、心肌酶、血清B型利钠肽(BNP)和心肌肌钙蛋白I(cTnI)水平、左室射血分数(LVEF),以及不良反应发生率情况。结果:200例乳腺癌患者中,发生心脏损伤49例(24.5%)。4组之间的心脏损伤发生率具有显著差异(P < 0.05),心脏损伤发生率排序为对照组(50.00%) > B组(24.00%) > A组(16.00%) > C组(8.00%)。多因素Logistic回归分析结果显示,心脏保护方案的使用、化疗周期数 > 3、蒽环类药物累积剂量 > 400 mg与心脏损伤的发生相关(P < 0.05)。化疗周期数 > 3、蒽环类药物累积剂量 > 400 mg是蒽环类药物致心脏毒性的独立危险因素,而使用心脏保护剂则是保护因素。对照组化疗后心电图异常发生率高于A、B、C组(P < 0.05)。化疗前各组患者心肌酶、BNP、cTnI、LVEF比较,差异无统计学意义(P > 0.05);化疗后对照组BNP、cTnI水平高于A、B、C组(P < 0.05)。4组化疗期间不良反应发生率差异无统计学意义(P > 0.05)。结论:右雷佐生联合磷酸肌酸钠用于蒽环类药物致乳腺癌患者心脏损伤有良好的效果且安全性较好。  相似文献   
36.
Hydrothermally synthesized Linde type A (LTA) and faujasite X (FAU-X) zeolites are low-cost and environmentally benign inorganic carriers for environmental applications. In this study, (oxy)hydroxides were incorporated onto LTA and FAU-X zeolites to promote the phosphate adsorption. The performance of LTA-Fe and FAU-X-Fe was evaluated through batch adsorption assays. A complete evaluation was performed to recover phosphate from synthetic wastewater. The effect of pH, concentration, equilibrium, and kinetic parameters on phosphate adsorption and its further reuse in sorption–desorption cycles were evaluated. LTA-Fe and FAU-X-Fe are effective for adsorption of phosphate at neutral (e.g., pH 7.0 ± 0.2) and in a broad range of phosphate concentrations. Higher ratios of adsorption capacities were obtained by synthetic zeolites enriched with iron in comparison to their parent forms. The phosphate adsorption occurred through hydrogen bonding and complexation reactions between protonated iron hydroxyl groups and phosphate anions. The phosphate monolayer adsorption was followed by diffusion through the internal pores and 80% of the equilibrium adsorption was reached within 50 min. The LTA-Fe and FAU-X-Fe can be used for phosphate recovery from wastewater treatment plants. The use of LTA-Fe and FAU-X-Fe in a tertiary wastewater treatment stage could allow to reduce the phosphate–phosphorous content, reaching the regulatory levels (equal 1 mg L−1 total phosphorous). The phosphate adsorption using LTA-Fe and FAU-X-Fe does not require pH adjustment, and it is endothermic. The reusability of both iron zeolites is limited, and they can be finally disposed for soil amendment applications.  相似文献   
37.
Zeng X  He H  Yang J  Yang X  Wu L  Yu J  Li L 《Journal of ethnopharmacology》2008,118(3):485-494
AIM: Cardiac infarction is one of the main causes of death in both developing and developed countries over past decades. Currently available approaches for treating patients with this disease are not satisfactory. Traditional Chinese medicines have been increasingly paid attention to. The aim of this study was to characterize the dynamic protective effects of Guanxin No. 2 decoction (GX II) on cardiac dysfunction combined with the blood viscosity and myocardial hypertrophy parameters in myocardial infarction (MI) rats. METHODS: Male Sprague-Dawley rats (180-200 g) were randomly divided into three groups: sham-operated, coronary artery ligation (CAL), and CAL plus GX II (GX II, 10.0 g raw materials/kg/d, bid, p.o.). The experiment was carried out at 4 time points as the 3rd, 7th, 14th, and 28th day after ligation. RESULT: It was found that on the one hand, GX II could significantly improve the heart function, and remarkably decrease infarct size and inhibit ventricular remodeling. On the other hand, GX II showed some unique effects such as angiogenesis which was induced in the left ventricular tissue. This result was consistent with the finding of an augmented vascular endothelial growth factor (VEGF) expression in this area. CONCLUSIONS: The studies demonstrated that GX II exerted extensively beneficial cardioprotective effect on CAL rats, it might stimulate angiogenesis of ischemic region to compensate blood supply to the heart via upregulated VEGF expression.  相似文献   
38.
How to treat the iron tailings of mining solid waste with high value is an urgent problem on a global scale. In recent years, the application of iron tailings in the building materials industry has attracted the attention of many scholars. The conversion of iron tailings into green building materials helps achieve carbon neutrality and high-value utilization of solid waste, and promotes sustainable development. Although iron tailings have been extensively studied as supplementary cementitious materials, the performance of concrete is not ideal due to its low activity. In this study, the hybrid supplementary cementitious materials system was prepared by iron tailings, phosphorus slag, and steel slag, and the effects of supplementary cementitious materials type, iron tailings content, iron tailings grinding time, and supplementary cementitious materials content on concrete performance were studied. The compressive properties, iron tailings properties, pore structure, interfacial transition zone, and element distribution of hydration products of concrete were tested by compressive strength tests, X-ray Diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS), Mercury Intrusion Porosimetry (MIP), Backscattering Electron Tests (BSE), and Energy Dispersive Spectrometer (EDS). The results show that further grinding improves the iron tailings activity. There is a synergistic mechanism between steel slag and phosphorus slag in the composite supplementary cementitious materials, which overcomes the low activity defect of iron tailings and produces concrete with a compressive strength exceeding 40 MPa. The composite supplementary cementitious materials can optimize the interfacial transition zone of the concrete interface and reduce the calcium–silicon ratio of the hydration products. However, it will deteriorate the pore structure of the concrete matrix, cause part of the concrete matrix to be damaged and lead to a loss of compressive strength, and the loss is acceptable. This work broadens the methods of comprehensive utilization of iron tailings and also provides a reference for a more detailed understanding of the properties of iron tailings-based concrete.  相似文献   
39.
目的 通过1例飞蚊症和腹泻的药物不良反应,探索磷酸氯喹治疗新型冠状肺炎的药学监护要点.方法 询问患者和医生,查阅文献,对照不良反应因果关系.结果 磷酸氯喹治疗新冠肺炎的日剂量大于不良反应文献报道及美国眼科学会推荐的视网膜安全剂量,磷酸氯喹的眼毒性与单次剂量和疗程有关.结论 建议治疗前行眼部基线检查,治疗中加强监测.  相似文献   
40.
A magnesium phosphate cement-based engineered cementitious composite (MPC-ECC) was developed using polyvinyl alcohol (PVA) fibers and fly ash. In this study, the bond behavior of MPC-ECC with ordinary concrete was evaluated through single and double shear bond strength tests. The effects of the water to solid mass ratio (W/S), the sand to binder mass ratio (S/B), the molar ratio of MgO to KH2PO4 (M/P), the fly ash content (F), the borax dosage (B), the volume fraction of PVA fibers (Vf), and curing age on the bond behavior of MPC-ECC with ordinary concrete were examined. The results showed that as the W/S increased, the single and double shear bond strengths were gradually reduced. As the S/B increased, the double shear bond strength increased; the single shear bond strength first decreased up to an S/B of 0.1 and then increased. With the increase of M/P, the single and double shear bond strengths increased. With the increase of F, the single shear bond strength first increased up to an F of 30% and then decreased; the double shear bond strength decreased. With the increase of B, the single and double shear bond strengths increased first and then decreased, and their strength reached its maximum at a B of 6%. The increase of Vf improved the single and double shear bond strengths. The research results can provide some technical guidance for repairing concrete structures with MPC-ECC.  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