全文获取类型
收费全文 | 51031篇 |
免费 | 5394篇 |
国内免费 | 1943篇 |
专业分类
耳鼻咽喉 | 471篇 |
儿科学 | 408篇 |
妇产科学 | 466篇 |
基础医学 | 6198篇 |
口腔科学 | 1448篇 |
临床医学 | 4723篇 |
内科学 | 5812篇 |
皮肤病学 | 464篇 |
神经病学 | 3596篇 |
特种医学 | 1796篇 |
外国民族医学 | 1篇 |
外科学 | 4826篇 |
综合类 | 8747篇 |
现状与发展 | 4篇 |
一般理论 | 1篇 |
预防医学 | 7431篇 |
眼科学 | 926篇 |
药学 | 5530篇 |
74篇 | |
中国医学 | 3195篇 |
肿瘤学 | 2251篇 |
出版年
2024年 | 305篇 |
2023年 | 1114篇 |
2022年 | 2186篇 |
2021年 | 2596篇 |
2020年 | 2203篇 |
2019年 | 1739篇 |
2018年 | 1679篇 |
2017年 | 1930篇 |
2016年 | 1847篇 |
2015年 | 1990篇 |
2014年 | 3246篇 |
2013年 | 3698篇 |
2012年 | 3033篇 |
2011年 | 3526篇 |
2010年 | 2673篇 |
2009年 | 2785篇 |
2008年 | 2770篇 |
2007年 | 2753篇 |
2006年 | 2315篇 |
2005年 | 2072篇 |
2004年 | 1650篇 |
2003年 | 1439篇 |
2002年 | 1093篇 |
2001年 | 989篇 |
2000年 | 914篇 |
1999年 | 768篇 |
1998年 | 607篇 |
1997年 | 552篇 |
1996年 | 467篇 |
1995年 | 424篇 |
1994年 | 415篇 |
1993年 | 306篇 |
1992年 | 305篇 |
1991年 | 224篇 |
1990年 | 242篇 |
1989年 | 187篇 |
1988年 | 160篇 |
1987年 | 159篇 |
1986年 | 116篇 |
1985年 | 162篇 |
1984年 | 129篇 |
1983年 | 83篇 |
1982年 | 92篇 |
1981年 | 80篇 |
1980年 | 76篇 |
1979年 | 68篇 |
1978年 | 40篇 |
1977年 | 38篇 |
1976年 | 31篇 |
1975年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Paul Roderick Ruth Davies Chris Jones Terry Feest Steve Smith Ken Farrington 《Nephrology, dialysis, transplantation》2004,19(3):692-701
BACKGROUND: The demand for renal replacement therapy (RRT) in England has risen steadily, although from a lower base than many other developed countries. Predicting the future demand for RRT and the impact of factors such as the acceptance rate, transplant supply and patient survival, is required in order to inform the planning of such services. METHODS: A discrete event simulation model estimates the future demand for RRT in England in 2010 for a range of scenarios. The model uses current prevalence and current and projected future acceptance rates, survival rates and the transitions between modalities to predict future patient numbers. National population and mortality data, published literature and data from the UK Renal Registry and UK Transplant, are used to estimate unmet need for RRT, the impact of changing demography and incidence of Type 2 diabetes, patient haemodialysis (HD) survival and transplant supply. RESULTS: By 2010 the predicted prevalence will have increased from about 30,000 in 2000 to between 42 and 51,000 (900-1000 p.m.p.), an average annual growth of 4.5-6%. Changing transplant supply has a small effect on overall numbers but changes the proportion of patients with functioning graft by up to 8%. Even with an optimistic increase in transplant supply (11% p.a. for 5 years), numbers on HD will continue to rise substantially, especially in the elderly. The factors most influencing future patient numbers are the acceptance rate and dialysis survival. CONCLUSION: This model predicts a substantial growth in the RRT population to 2010 to a rate approaching 1000 p.m.p., particularly in the elderly and those on HD, with a steady state not being reached for at least 25 years. 相似文献
92.
大学生心理健康教育干预研究 总被引:11,自引:2,他引:9
目的 研究高校心理健康干预模式 ,提高大学生心理健康水平。方法 采取分层整群抽样的方法 ,运用SCL - 90自评量表对该院学生测试评分 ,分别进行实施心理健康干预模式 (心理教育、心理预防、心理训练 )前后状况调查 ,比较学生心理测试总体水平。结果 学校心理健康教育干预实施后一年 ,学生心理测试 8项因子分均值低于心理健康干预实施前 ,其中强迫、人际关系、焦虑、恐怖、偏执因子分实施前后有显著性差异 (P <0 0 5 )。结论 学校实施心理健康教育干预能有效地维护大学生心理健康 ,促进大学生心理发展 ,提高大学生心理素质 相似文献
93.
目的:探索中药水蛭、海螵蛸、阿胶、骨碎补在骨折愈合过程中的干预作用,了解它们各自的调节靶点,探索建构其基因组学的途径。方法:通过在大鼠胫骨打孔的方法建立单因素干扰模型,并将300只大鼠随机分为正常组、模型组和给药组(分别用4种中药给药),每组50只,分别在实验的第4、7、14、21、28天不同时间点采用原位杂交方法对各类mRNA的变化进行动态观察,分析骨愈合过程中Ⅰ、Ⅱ、Ⅲ型前胶原mRNA、转化生长因子TGF-β1mRNA、骨形态发生蛋白BMP-2mRNA以及血管内皮生长因子VEGF-mRNA的表达情况。结果:不同中药对不同基因的作用不同,作用的时间点不同,作用强度也存在差异。其中海螵蛸在骨折早期对Ⅰ、Ⅲ型前胶原mRNA、VEGF-mRNA、BMP-2mRNA的表达升高,后期Ⅱ、Ⅲ型前胶原mRNA表达水平下降,VEGF-mRNA、TGF-β1mRNA表达量维持于较高水平;骨碎补组较模型组在BMP-2mRNA、TGF-β1mRNA、Ⅰ型前胶原mRNA的表达上差异有显著性统计意义;阿胶对骨愈合早、中期Ⅰ、Ⅱ、Ⅲ型前胶原mRNA和TGF-β1mRNA的表达与模型组比较差异存在显著性统计意义;水蛭对VEGF-mRNA的表达具有一定的促进作用。结论:海螵蛸、水蛭对血管形成有促进作用,阿胶、骨碎补和海螵蛸对骨折软骨形成早期具有促进骨诱导的作用,并对成骨细胞的增殖及合成活性有较大影响。 相似文献
94.
95.
Depressive Symptoms and Associated Factors in Children With Attention Deficit Hyperactivity Disorder
Nancy LeBlanc PhD RN Diane Morin PhD RN 《Journal of child and adolescent psychiatric nursing》2004,17(2):49-55
PROBLEM: To compare depressive symptoms in children with attention deficit hyperactivity disorder (ADHD) to those in healthy children, and to explore the influence of individual and family factors on level of depression. METHODS: Individual interviews with 68 children, ages 7 to 12 years, in order to complete the Children's Depression Inventory. FINDINGS: Children with ADHD reported significantly more depressive symptoms than did children without ADHD; 14.7% of children with ADHD reached the threshold of a 19 point score, which suggests clinical depression. No significant effects of individual and family factors on level of depression were found. CONCLUSIONS: Children with ADHD are more inclined to experience depressive symptoms than are healthy children. To plan appropriate interventions, nurses evaluating and working with children with ADHD should always consider a possible coexistence of depressive symptoms. 相似文献
96.
内镜腔内手术的实验研究 总被引:5,自引:3,他引:2
目的探讨内镜腔内手术的可行性. 方法 6只家猪经皮建立胃内通道,腹腔镜引导下胃内模拟缝合止血操作实验. 结果 6只家猪均很好地耐受了手术.术后开腹检查所有胃壁缝合处无渗漏及其它脏器损伤.建立胃内通道时间、胃内缝合时间及总手术时间分别为(60.5±12.2)min、(26.5±5.78)min和(92.1±15.0)min. 结论内镜腔内手术在技术上是可行的. 相似文献
97.
立体着床模型--小鼠囊胚与子宫内膜的共培养 总被引:1,自引:0,他引:1
目的:建立小鼠囊胚体外着床的三维模型,为着床机制的研究提供重要工具.方法:将小鼠囊胚与其自身子宫内膜分别共培养在空气、含500,750和950 mL/L O2的混合气体与组织培养液的气液界面上,比较不同O2浓度下小鼠囊胚的贴附率,确定体外共培养的最佳O2浓度;同时将确认有囊胚贴附的子宫内膜取出作HE染色.结果:不同O2浓度下,囊胚的贴附率分别为64.75%,47.86%,42.37%和30.97%,x2检验提示其差异有显著性(x2=28.145,P=0.000);且随着混合气体中O2浓度的逐渐升高,囊胚贴附率呈逐渐降低趋势.因此50 mL/L CO2 950 mL/L空气对囊胚与子宫内膜的共培养是最有利的;同时,囊胚贴附子宫内膜后并无扩展行为而是直接侵入子宫内膜.结论:50 mL/L CO2 950 mL/L空气最有利于囊胚与子宫内膜的共培养;且囊胚贴附子宫内膜后不发生外延生长,而是直接侵入子宫内膜.本实验成功地建立了小鼠囊胚体外着床的三维模型. 相似文献
98.
D M McSherry 《Statistics in medicine》1986,5(5):497-502
The independence Bayesian model has been used widely in computer programs designed to support clinical decision-making. A reasoning strategy has been developed to enable these programs to conduct clinically pertinent dialogue and explain their reasoning. It has been implemented in a program for the diagnosis of acute abdominal pain based on the Bayesian model of de Dombal et al. Several features of the dialogue design have been adopted from artificial intelligence research, including shared initiative and critiquing. The program adopts a flexible goal-driven strategy, attempting to confirm the clinician's diagnosis or rule out the likeliest alternative. Symptoms and signs are selected in order of their expected weights of evidence in favour of the hypothesized disease. 相似文献
99.
Aoyama Takao Yamamoto Koujirou Kotaki Hajime Sawada Yasufumi Iga Tatsuji 《Pharmaceutical research》1997,14(11):1601-1606
Purpose. The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed.
Methods. MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis.
Results. The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 ± 73.8 nM (mean ± SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model.
Conclusions. The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may be useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine. 相似文献
100.
Modulation of cytokine production from an EpiOcular corneal cell culture model in response to Staphylococcus aureus superantigen 总被引:3,自引:0,他引:3
A Thakur PhD A Clegg MSc A Chauhan MSc MDP Willcox PhD 《Clinical & experimental ophthalmology》1997,25(4):43-45
The present study investigated the hypothesis that Staphylococcus aureus enterotoxin B (SEE) produces epithelial cell death and releases inflammatory cytokines that produce stromal infiltration during contact lens induced peripheral ulceration. Epithelial cells were incubated with different doses of SEB for various time periods. Culture supernatants were assayed for cytokines IL- lo, IL-6 and chemotactic agents IL-8 and LTB,. SEE induced the production of IL- I p and IL-8. Epithelial cells exposed for longer periods (48 h) with low concentrations of SEB produced significantly higher levels (N0.02) of IL-Ip and IL-8 (P<0.05) compared t o a 24 h exposure. SEB did not induce the production o f IL-6 and 相似文献