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   369540篇
  免费   25258篇
  国内免费   8142篇
耳鼻咽喉   4888篇
儿科学   9890篇
妇产科学   6729篇
基础医学   29397篇
口腔科学   8899篇
临床医学   40405篇
内科学   43956篇
皮肤病学   4725篇
神经病学   20526篇
特种医学   9142篇
外国民族医学   33篇
外科学   42880篇
综合类   56451篇
现状与发展   14篇
一般理论   33篇
预防医学   36867篇
眼科学   5790篇
药学   32371篇
  449篇
中国医学   34327篇
肿瘤学   15168篇
  2023年   5788篇
  2022年   8804篇
  2021年   14387篇
  2020年   13621篇
  2019年   19375篇
  2018年   16883篇
  2017年   13987篇
  2016年   11528篇
  2015年   10735篇
  2014年   21963篇
  2013年   23442篇
  2012年   20022篇
  2011年   22065篇
  2010年   18134篇
  2009年   16185篇
  2008年   15562篇
  2007年   16123篇
  2006年   14204篇
  2005年   12285篇
  2004年   9937篇
  2003年   8741篇
  2002年   6855篇
  2001年   6159篇
  2000年   5077篇
  1999年   4354篇
  1998年   3572篇
  1997年   3365篇
  1996年   2888篇
  1995年   2753篇
  1994年   2653篇
  1993年   2112篇
  1992年   2157篇
  1991年   1852篇
  1990年   1650篇
  1989年   1474篇
  1988年   1383篇
  1987年   1188篇
  1985年   3900篇
  1984年   4904篇
  1983年   3420篇
  1982年   3910篇
  1981年   3650篇
  1980年   3254篇
  1979年   2974篇
  1978年   2600篇
  1977年   1957篇
  1976年   2198篇
  1975年   1665篇
  1974年   1452篇
  1973年   1294篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The pharmacokinetics and haemodynamic effects of isosorbide dinitrate (ISDN) have been investigated following administration of single doses as a sublingual (SL) spray (2.5 mg), sublingual tablet (5 mg) and peroral tablet (10 mg) in a randomised, placebo-controlled double-blind cross-over trial in 16 healthy volunteers.After the sublingual spray Cmax was higher (39.0 ng·ml-1) and tmax was shorter (3.9 min) than after the sublingual (22.8 ng·ml-1 and 13.8 min) and peroral (16.9 ng·ml-1 and 25.6 min) tablets. The AUC of ISDN did not differ following any of the three formulations (1031; 879; 997 ng·ml-1·min, for the spray, SL tablet and PO-tablet, respectively). Mononitrate metabolites of ISDN (IS-2-MN and IS-5-MN) and total nitrates in plasma increased in proportion to the administered dose. This indicates that the fraction of the dose absorbed was the same for all the formulations but that the extent of first-pass metabolism increased in the order sublingual spray < sublingual tablet < peroral tablet. Thus, compared to the spray, the relative bioavailability of ISDN was 48% and 28% from the sublingual and peroral tablets, respectively.The haemodynamic effects were quantified using the a/b ratio of the finger pulse wave and the systolic blood pressure and heart rate under orthostatic conditions. For the a/b ratio of the finger pulse, the maximal effect was higher (emax=130%) and the time to emax (temax) shorter (16.6 min) after the spray than the sublingual tablet (84.4% and 25.5 min) or peroral tablet (90.2 and 31.3 min). The onset of effect was within 3, 5 and 7.5 min after the spray, sublingual and peroral tablets, respectively. A larger change in the orthostatically-induced decrease in systolic blood pressure and increase in heart rate was obtained following peroral than sublingual administration despite the similar plasma concentrations of ISDN. This probably reflects the larger amount of pharmacodynamically active mononitrate metabolites formed after oral dosing. The integrated effect following administration of 2.5 mg ISDN as spray was similar to that of a sublingual tablet of 5 mg.  相似文献   
992.
Twenty-four patients treated with 150 mg amitriptyline per day for an episode of major depression underwent a standardized heart rate analysis (HRA) before therapy and after 14 days. The battery of cardiovascular reflex tests included the determination of the coefficient of variation (CV) while resting and during deep respiration, a spectral analysis of heart rate, the heart rate response to standing, and the Valsalva manoeuvre. The results of the initial HRA did not differ from a group of 24 normal control subjects matched for age and sex. On day 14 of treatment the patients showed significantly reduced values of heart rate variability in all tests (P<0.0001), probably due to the anticholinergic side effects of amitriptyline. Heart rate increased form 78.1 to 93.6 bpm on average (P<0.0001). Abnormal CV at rest was registered in 96% of the patients; during deep respiration 29% showed abnormal CV results. An abnormal spectral analysis was found in 100% of the cases (low frequency peak: 42%, mid-frequency peak: 100%, high frequency peak: 79%). The heart rate response to standing was abnormal in 75% and the Valsalva test in 33% of the cases. Eighty-eight percent of the patients fulfilled the criteria of a cardiovascular autonomic neuropathy under the conditions of amitriptyline therapy. As yet, the consequences of these changes for the patients have not been sufficiently elucidated.  相似文献   
993.
The D2-dopamine receptor antagonist raclopride was administered to eight healthy male subjects, who had previously experienced akathisia following antipsychotic drugs. The influence of administration rate on onset, severity and duration of akathisia and on prolactin response was studied. Raclopride 3,5 or 9 mg or placebo (P) was administered as single IV infusions during 10 min (R10 min/3 mg), 1 h (R1h/5 mg) or 4 h (R4h/9 mg) according to a randomized double-blind design. Despite a 24-fold difference in administration rate a similar peak raclopride concentration of about 350 nmol/l was obtained after all three infusions. Three of the eight subjects experienced akathisia following R10 min/3 mg and R1h/5 mg, respectively. After R4h/9 mg seven subjects experienced akathisia of longer duration but not more severe than after the short infusions. The incidence and duration of akathisia seem to be mainly related to the plasma raclopride concentrations over time, whereas the rate of administration might be more important for the severity. A maximal prolactin response was induced which was not markedly affected by the rate of administration.  相似文献   
994.
应用国产ELISA试剂盒对157例肝癌、肝硬化病人血清中抗-HCV及HBV-M进行检测,101例肝癌10例抗-HCV阳性,阳性率为9.9%;56例肝硬化6例抗-HCV阳性,阳性率为10.7%;肝癌组抗HCV与HBsAg双阳性率79%(8/101),HBsAg阳性率为723%(73/101),明显高于HCV感染率,说明HBV仍是乙肝流行地区的主要相关因素。14例抗-HCV阳性(包括可疑阳性),肝癌外周血中8例(57.1%)HBsAg阳性,推测HCV可单独作用但更常与HBV形成混合感染参与慢性肝病的癌变过程。  相似文献   
995.
采用综合治疗,抗炎,散瞳,局部治疗与全身应用免疫抑制疗法,治疗319例352眼外伤获得了满意的疗效,眼球挫伤104例,眼球穿孔伤93例,化学烧伤71例,眼炸伤46例。眼热烧伤5例,治疗包括及时清创胶粘或缝合,清除前房出血合理用皮质类固醇和免疫抑制剂等。眼球挫伤治愈率97.12%,穿透伤93.18%,热烧伤66.67%。319例眼外伤治愈率94.67%好转5.33%,并对各种治疗方法进行了讨论。  相似文献   
996.
联合抗青光眼手术治疗不易控制眼压青光眼的研究   总被引:1,自引:0,他引:1  
采用板层下巩膜床双咬切、睫状体剥离合并睛状体上腔植入硅橡胶条的抗青光眼联合手术治疗不易控制眼压的青光眼46例52眼,其中继发性青光眼27眼,原发闭角青光眼10眼,原发开角青光眼6眼,先天、青少年型青光眼7眼,虹膜角膜内皮综合征2眼。手术总有效率达94%。本术式具有小梁切除、睫状体剥离、睫状体扁平部引流的功能。作者认为用硅橡胶条作植入物,比异体或自体组织作植入物更为理想。  相似文献   
997.
From January 1986 to December 1991 we examined the eyes of 206 infants born at Westmead Hospital, Neonatal Intensive Care Unit who were less than 29 weeks' gestation at birth to determine the incidence of retinopathy of prematurity. Eighty-five infants (41.3%) had no retinopathy of prematurity (ROP) in either eye, 82 infants had stages 1 or 2 ROP (39.8%), 29 had stage 3 ROP (14.1%) and 11 had stage 4 ROP (5.3%). Of these, cryotherapy was performed in 18; six now have bilateral retinal detachment and are blind The more severe stages of ROP were significantly associated with an increase in the number of days of oxygen supplementation, an increase in the number of days of mechanical ventilation and the presence of patent ductus arteriosus. Infants receiving steroids for mechanical ventilator dependence had a significantly greater chance of requiring cryotherapy (11 or 22 receiving steroids versus seven of 43 without steroids; P < 0.01).  相似文献   
998.
医院综合效益评价案例分析   总被引:2,自引:0,他引:2  
运用层次分析法建立了医院综合效益评价指标体系,开发了医院综合效益九型评价图,用于显著评价结果。在此基础上进行了3个案例的评价分析。论述了通过对西南地区27所医院综合效益4年多的追踪分析所发现的共性问题,并提出了相应的管理对策。  相似文献   
999.
镉对肾脏的毒作用   总被引:6,自引:0,他引:6  
雄性Wistar大鼠24只,随机等分为4组,皮下注射不同剂量的CdMT。结果显示镉接触组尿钙和尿蛋白都高于对照组;肾皮质钠泵和钙泵活性低于对照组,体外试验也显示镉能抑制钙泵活性,GSH和半胱氨酸对这种抑制有保护作用;肾皮质GSH含量低于对照组,MDA含量则高于对照组,但肝脏的这两个指标无变化;高剂量组cAMP/cGMP的比值低于对照组。提示脂质过氧化和钙代谢障碍是镉引起肾损害的机理之一。  相似文献   
1000.
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