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   9774篇
  免费   781篇
  国内免费   203篇
耳鼻咽喉   35篇
儿科学   232篇
妇产科学   66篇
基础医学   1182篇
口腔科学   173篇
临床医学   690篇
内科学   2347篇
皮肤病学   65篇
神经病学   760篇
特种医学   504篇
外科学   805篇
综合类   830篇
现状与发展   2篇
预防医学   1431篇
眼科学   89篇
药学   925篇
  1篇
中国医学   402篇
肿瘤学   219篇
  2024年   32篇
  2023年   176篇
  2022年   600篇
  2021年   669篇
  2020年   403篇
  2019年   328篇
  2018年   354篇
  2017年   310篇
  2016年   309篇
  2015年   374篇
  2014年   579篇
  2013年   685篇
  2012年   453篇
  2011年   547篇
  2010年   419篇
  2009年   405篇
  2008年   400篇
  2007年   405篇
  2006年   287篇
  2005年   323篇
  2004年   212篇
  2003年   230篇
  2002年   198篇
  2001年   194篇
  2000年   162篇
  1999年   148篇
  1998年   148篇
  1997年   133篇
  1996年   111篇
  1995年   111篇
  1994年   108篇
  1993年   97篇
  1992年   100篇
  1991年   94篇
  1990年   76篇
  1989年   86篇
  1988年   51篇
  1987年   54篇
  1986年   49篇
  1985年   41篇
  1984年   53篇
  1983年   50篇
  1982年   43篇
  1981年   39篇
  1980年   24篇
  1979年   26篇
  1978年   14篇
  1977年   8篇
  1976年   10篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Research on the contribution of CRH receptor stimulation to energy homeostasis has focused on forebrain substrates. In this study, we explored the effects of caudal brainstem administration of the CRH receptor agonist, urocortin, on food intake and body weight, and on plasma glucose and corticosterone (CORT) in non-deprived rats. Urocortin (0, 0.3, 1, 3 microg) delivered, respectively, to the fourth and lateral ventricles yielded substantial suppression of food intake measured 2, 4 and 24 h later. A significant but more modest anorexia was observed between 24 and 48 h after injection. Intake responses did not differ between the injection sites, but body weight loss measured 24 h after lateral-i.c.v. injection was substantially greater than that after fourth-i.c.v. injection. Fourth-i.c.v. urocortin administration (3 microg) produced substantial elevations in plasma glucose and CORT that were not distinguishable in magnitude and duration from responses to lateral-i.c.v. delivery. Unilateral microinjection of urocortin into the dorsal vagal complex significantly reduced 24-h food intake at a dose (0.1 microg) that was subthreshold for the response to ventricular administration, suggesting that fourth-i.c.v. effects are mediated in part by stimulation of CRH receptors in this region of the caudal brainstem. The results indicate that similar effects can be obtained from stimulation of anatomically disparate populations of CRH receptors, and that interactions between forebrain and hindbrain structures should be considered in the evaluation of CRH contributions to food intake and body weight control.  相似文献   
102.
目的:为了正确了解中学生的营养状况,从而指导学生科学用膳,促进学生健康,提高学习质量.方法:以浙江台州中学学生为对象,进行一周的营养膳食调查.结果:经过计算、分析、比较,认为该校学生的蛋白质、热能、钙、维生素A等营养素摄入量不足,且热能来源比例不合理,有待合理调整和安排日常膳食.  相似文献   
103.
It has been reported that benzylamine reduces blood glucose in rabbits, stimulates hexose uptake, and inhibits lipolysis in mouse, rabbit, and human adipocytes. In the presence of vanadate, benzylamine is also able to improve glucose disposal in normoglycaemic and diabetic rats. Such insulin-mimicking properties are the consequence of hydrogen peroxide production during benzylamine oxidation by semicarbazide-sensitive amine oxidase (SSAO). The aim of the study was to determine whether other SSAO-substrates could share such potential antidiabetic properties. Thus, mafenide, a synthetic antimicrobial sulfonamide structurally related to benzylamine, and which has been recently reported to interact with SSAO, was tested in the above mentioned models, in parallel with methylamine, a proposed endogenous SSAO-substrate. All tested amines stimulated glucose uptake and inhibited lipolysis in rat and mouse fat cells. Methylamine and benzylamine, but not mafenide, reduced the hyperglycaemic response during a glucose tolerance test in rabbits while the three amines tested were devoid of insulin-releasing activity under both in vivo and in vitro conditions. In human adipocytes, mafenide did not stimulate glucose transport since it was not a high-affinity substrate for SSAO and generated less hydrogen peroxide than benzylamine or methylamine. Therefore, mafenide could not be considered as an antidiabetic drug despite being oxidized and exhibiting insulin-mimicking effects in rat and mouse adipocytes. By contrast, the endogenous substrate methylamine improved glucose utilization in all in vitro and in vivo models, leading to consider novel SSAO substrates as drugs with potential anti-hyperglycaemic properties.  相似文献   
104.
非骨水泥型假体周围早期骨密度变化临床观察   总被引:5,自引:0,他引:5  
为观察非骨水泥型假体置换术后周围骨密度的变化,对25例非骨水泥型人工假体置换患者分别于术后1周、3个月及6个月应用双能X线骨密度仪,按Grune[1]分7个测量兴趣区测量假体周围骨密度.结果显示假体周围骨密度术后3个月平均丢失11.7%,6个月平均丢失17.77%.其中以1和7区明显,1区术后3、6个月分别减少21.25%、25.55%(P<0.01),7区术手3、6个月分别减少22.80%、32.14%(P<0.01).说明假体置换术后早期周围骨密度均有不同程度的减少,其中以假体近端(1、7区)明显,且骨量丢失以术后前3个月最为显著.  相似文献   
105.
目的:探讨宫腔镜组织切除系统在输卵管间质部妊娠中治疗的可行性及安全性。方法:收集2019年4月至2022年4月江西省妇幼保健院妇科收治的采用宫腔镜组织切除系统治疗的16例未破裂型输卵管间质部妊娠患者的临床资料,回顾性分析患者的术前血β-人绒毛膜促性腺激素(beta-human chorionic gonadotropin,β-HCG)、B超情况、手术时间、术中出血量及术后血β-HCG正常时间等。结果:16例未破裂型输卵管间质部妊娠患者术前血β-HCG值为830~31 153 mIU/mL,平均(8 643.561±1 752.000) mIU/mL,B超下妊娠物最大为33 cm×28 cm,最小为11 cm×10 cm。均在检查镜下明确诊断为输卵管间质部妊娠,使用宫腔镜组织切除系统行间质部妊娠病灶清除术,其中2例中转腹腔镜,平均手术时间为34(20,92) min,平均术中出血量为46.6(10,250) mL,术程顺利,无明显并发症。术后平均住院时间2 d,血β-HCG恢复正常时间为(22.00±5.11) d,术后1个月复查B超均未见妊娠组织残留,术后半年随访过程中共5例患者成功受...  相似文献   
106.
婴儿钙营养缺乏的影响因素   总被引:3,自引:0,他引:3  
目的分析婴儿期钙营养状况的有关影响因素,为早期防治和改善婴儿钙营养状况提供科学依据。方法随机抽取武汉地区0~1岁婴儿,采用双能X线吸收法(DEXA)检测其骨密度(bone mineral density,BMD),将BMD值正常者列入对照组,BMD值异常者列入病例组,采用1:1配对病例对照研究,共计133对。采用统一自制的调查表进行问卷调查,对婴儿BMD的有关影响因素进行回归分析。结果经多因素条件Logistic回归分析,婴儿BMD的主要不良影响因素依次为早产适于胎龄儿、出生窒息、低出生体重、食欲不佳和呼吸道感染,OR值分别为0.465、0.301、0.598、0.560和0.616。添加动物食物量、户外活动时间和补钙剂量为BMD的有利因素,OR值分别为0.526、0.435和0.998。结论婴儿期BMD受到来自孕期、围产期、营养和疾病等多种因素的影响,应降低围产期高危因素,婴儿期要及时调整膳食结构,加强户外活动,适当补充钙剂和鱼肝油,改善婴儿钙营养状况。  相似文献   
107.
目的探讨应用桥接钢板治疗长管状骨高能量损伤的临床疗效。方法应用桥接钢板的形式治疗长管状骨的高能量损伤37例。其中股骨粉碎性骨折12例,胫腓骨粉碎性骨折17例,肱骨粉碎性骨折3例,尺桡骨粉碎性骨折5例。结果全部病例得到随访,时间45d~2年,1年内骨性愈合34例,延迟愈合3例,无骨不连病例。根据自定的长管状骨愈合评价标准,本组优21例,良13例,中3例。结论长管状骨的高能量损伤骨折形式复杂,治疗较棘手,应用桥接钢板的形式进行治疗可最大限度地保留骨折部的血运,有利于骨折的按期愈合及减少并发症。  相似文献   
108.
The aim of this study was to assess the possibilities to use brewer’s spent grains (BSGs) left over from beer production for energy purposes, and to determine its calorific value and chemical composition. The research materials were samples of wet spent grain from a brewery in Poland. Three samples, that are different in ingredient composition, were examined. The examined samples of BSGs were characterised by humidity that is typical for this product (approx. 77–80%). Convective drying of the spent grain contributed to a reduction in the water content in the biomass to below 10%. Samples of dry spent grain that were examined contained a similar amount of ash (3.8–4.1% d.m.) and organic matter (91.0–91.9% d.m.). All the examined spent grain samples demonstrated similar volatile matter content—approx. 77.8–78.7% d.m. and calorific value—approx. 15.6–15.9 MJ/kg. The estimated calorific value for wet samples (approx. 1.4–2.0 MJ/kg) indicated that it is necessary to lower water content in the biomass in order to improve its energy properties.  相似文献   
109.
Cannabidiol (CBD) is widely available and marketed as having therapeutic properties. Over-the-counter CBD is unregulated, many of the therapeutic claims lack scientific support, and controversy exists as to the safety of CBD-liver interaction. The study aims were to compare the pharmacokinetics of commercial CBD and CBD metabolites following the ingestion of five different CBD formulations, determine the influence of CBD on food induced thermogenesis, determine the influence of food on CBD pharmacokinetics, and determine the influence of CBD on markers of liver function. Fourteen males (body mass index ≥ 25 kg/m2) were studied in a placebo-controlled, randomized, crossover design. On five occasions, different CBD formulations were ingested (one per visit). On two additional occasions, CBD or placebo was ingested following a meal. CBD servings were standardized to 30 mg. Considerable pharmacokinetic variability existed between formulations; this pharmacokinetic variability transferred to several of the metabolites. CBD did not influence food induced thermogenesis but did favorably modify early insulin and triglyceride responses. Food appreciably altered the pharmacokinetics of CBD. Finally, CBD did not evoke physiologically relevant changes in markers of liver function. Collectively, these data suggest that consumers should be aware of the appreciable pharmacokinetic differences between commercial CBD formulations, CBD is unlikely to influence the caloric cost of eating but may prove to be of some benefit to initial metabolic responses, consuming CBD with food alters the dynamics of CBD metabolism and increases systemic availability, and low-dose CBD probably does not represent a risk to normal liver function.  相似文献   
110.
The Smith-Watson-Topper parameter (SWT) in its original form was designed to estimate the fatigue life of metal materials in a uniaxial load state (tension–compression) in the range up to fatigue crack initiation, with non-zero mean values. This parameter is based on the analysis of both stress and strain. Therefore, the stress–strain criterion is the focus, rather than the energy criterion. This paper presents the original SWT model and its numerous modifications. The first part presents different versions of this parameter defined by the normal parameters. Then, it presents versions defined through the tangent parameter and the most promising parameter defined through the tangent and normal parameters. It was noted that the final form of the equivalent value is defined either by stress or by an energy parameter. Therefore, the possible characteristics from which the fatigue life can be determined are also presented.  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