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   32308篇
  免费   1566篇
  国内免费   116篇
耳鼻咽喉   368篇
儿科学   1044篇
妇产科学   911篇
基础医学   4239篇
口腔科学   965篇
临床医学   3042篇
内科学   6530篇
皮肤病学   652篇
神经病学   2898篇
特种医学   1100篇
外科学   3852篇
综合类   783篇
现状与发展   1篇
一般理论   9篇
预防医学   2776篇
眼科学   648篇
药学   2358篇
中国医学   186篇
肿瘤学   1628篇
  2023年   245篇
  2022年   351篇
  2021年   801篇
  2020年   480篇
  2019年   672篇
  2018年   924篇
  2017年   712篇
  2016年   776篇
  2015年   799篇
  2014年   1020篇
  2013年   1434篇
  2012年   2117篇
  2011年   2217篇
  2010年   1153篇
  2009年   1002篇
  2008年   1804篇
  2007年   1850篇
  2006年   1771篇
  2005年   1888篇
  2004年   1861篇
  2003年   1874篇
  2002年   1714篇
  2001年   728篇
  2000年   686篇
  1999年   668篇
  1998年   319篇
  1997年   264篇
  1996年   170篇
  1995年   166篇
  1994年   151篇
  1993年   140篇
  1992年   310篇
  1991年   257篇
  1990年   211篇
  1989年   237篇
  1988年   182篇
  1987年   201篇
  1986年   181篇
  1985年   165篇
  1984年   102篇
  1983年   88篇
  1982年   69篇
  1981年   64篇
  1980年   63篇
  1979年   110篇
  1978年   71篇
  1977年   82篇
  1975年   70篇
  1974年   76篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
OBJECTIVE: In our previous study, auditory event-related potentials (AERPs) in preterm 1-year-old children had a positive deflection at 150-350 ms that correlated positively with their 2-year neurodevelopmental outcome. In a study of the same subjects at age 5, our aim was to assess AERPs and their relationship to neuropsychological test results. METHODS: Preterm small (SGA, n=13), appropriate for gestational age (AGA, n=15), and control (n=13) children were assessed with an Easy paradigm presenting a large frequency change accompanied with occasional novel sounds, and a Challenging paradigm presenting small frequency and duration changes with a rapid rate. The preterm children underwent neurocognitive tests. RESULTS: Easy paradigm. The P1 response to frequency deviant was smaller and MMN larger in the preterm than in the control children. Challenging paradigm. The P1 response to standard, frequency, and duration deviants was smaller in the preterm than in the control children. The N2 response to frequency deviant was larger in the preterm than in the control children. AGA and SGA children had similar AERPs. The P1, N2, and MMN amplitudes correlated with verbal IQ and NEPSY language subtests. CONCLUSIONS: Small P1 response(s) appears to be typical for preterm children. SIGNIFICANCE: Small P1 response in preterm children may suggest altered primary auditory processing.  相似文献   
52.
BACKGROUND: Chlorofluorocarbon (CFC)-free metered-dose inhalers (MDIs) were introduced into Australia in 1999. Device care instructions were modified (e.g., CFC-free salbutamol inhalers to be washed weekly), but this information was not communicated directly to health care professionals. OBJECTIVE: This pilot study aimed to assess the level of awareness of device care protocols for CFC-free MDIs by patients and their pharmacists. SETTING AND DESIGN: Purchasers of CFC-free MDIs were recruited from four community pharmacies. They were interviewed regarding information sources, knowledge of propellant change, and awareness of and adherence to device care protocols. The dispensing pharmacists were interviewed for knowledge of CFC-free device care. The primary outcome variable was awareness of the relevant device care protocol. RESULTS: Thirty-nine patients were interviewed. Most patients (77%) were aware of the change to CFC-free propellant. Only nine patients (23%) were aware of the need to wash the device holder, and four patients (10% of total) complied with the specified protocol. One of the ten dispensing pharmacists could describe correct device care protocols for the CFC-free MDIs. CONCLUSIONS: Although most patients are aware that MDIs are now CFC-free, there is a low level of awareness of the device care required for these inhalers, and a very low rate of compliance with recommended practice. Although the clinical impact of failing to wash the device holder is unclear, this added instruction may have substantial implications for patient satisfaction and medication delivery. Pharmaceutical manufacturers need to highlight to health care professionals any clinically important changes in device care instructions, so that appropriate information may be passed on to patients.  相似文献   
53.
54.
Abstract The anti-inflammatory properties of triclosan have been revealed in several recent studies, including an effect on histamine-induced inflammation. In other studies, the nature of the solvent has been shown to be of importance for the plaque inhibiting as well as the antibacterial potential of triclosan. This study was aimed at examining whether the nature of the solvent also may influence the anti-inflammatory capacity of triclosan and further to study a possible dose/response relationship. The study was performed as 3 separate, double-blind experiments, comprising 10, 11 and 12 healthy females. In all 3 experiments, 5 sites on the lower part of the back of the volunteers were intradermally exposed to one drop of 1% histamine dihydrochloride for 15 min. The size of the resulting wheals was recorded before and after 40 min of triclosan treatment. In experiment I. 4 different concentrations of triclosan in 2-fold dilutions in absolute alcohol (0.125%-1%) were applied on the histamine-induced wheals. In experiments 2 and 3, 4 different solutions containing 0.5% triclosan and a saline solution as negative control were used. The solvents in experiment 2 were as follows: (1) absolute alcohol (positive control). (2) propylene glycol (PG), (3) polyethylene glycol (PEG). (4) olive oil, and in experiment 3: (1) absolute alcohol (positive control). (2) Tween 80. (3) sodium carbonate, (4) soy oil. The results showed a dose/ response effect of triclosan and further that the solvent may be of importance for its anti-inflammatory potential.  相似文献   
55.
56.
Psychopathological reactions to fatherhood are probably not so infrequent as they would seem from psychiatric literature. In a material of paranoid psychoses, impending or newly established fatherhood was considered the main precipitating factor in 4 patients (i.e. 2.4%), compared with 7% of the female psychoses precipitated by pregnancy, childbirth or nursing. Two of the men were bachelors, insecure and inhibited, feeling compromised or helpless in the new situation. Two men were married, passive, avoidant in their personality, strongly dependent on their wives. The course and outcome varied according to the diagnoses; 2 cases having a favorable and 2 an unfavorable course and outcome. Physicians, including psychiatrists, should bear in mind that fatherhood is a possible precipitating factor for paranoid psychoses in male patients.  相似文献   
57.
Pregnancies in which fetal cardiac arrhythmias are present are associated with an elevated perinatal and neonatal mortality. In this group various major and minor fetal malformations, including heart malformations, are more common. FECG and phonocardiogram give some information on the type of arrhythmia in favorable cases. Real-time imaging detects fetal heart malformations and late signs of heart failure. Fetal echocardiogram is of great aid for the classification of the arrhythmia and for the detection of heart malformations. By applying combined real-time linear array and pulsed Doppler technique in cases of fetal cardiac arrhythmia, important information on the fetal circulatory state can be obtained. Estimations of the volume blood flow guide the clinician in the practical handling of these cases. Volume blood-flow estimations can probably detect imminent fetal heart failure. Therapeutic effects can be followed, and the timing of delivery can be optimized taking the circulatory state into account. Within the fetal heart rate range 50 to 250 beats/min adequate blood circulation is usually maintained in the fetus. The peak velocity, the acceleration, and the rising slope are all increased in the postextrasystolic beat, indicating the existence of postextrasystolic potentiation in the fetal heart. These three parameters can be related to the ventricular filling time, supporting the opinion that the fetal heart follows the rules of the Frank Starling relationship. Fetal arrhythmias constitute also an experimental model for the study of fetal cardiac physiology.  相似文献   
58.
S Zalányi  A Pál  E Szabó 《Orvosi hetilap》1989,130(4):173-175
Experiences with the methods are summarized. Follicular growth was monitored by ultrasound folliculometry (USFM) and estimation of serum estradiol (E2 values in physiologic cycles. USFM was found to predict follicular rupture-ovulation--more precisely than E2 values. Cases of disturbed folliculogenesis (persisting and luteinized unruptured follicle, cysts) are described. The wider use of USFM in Hungary is urged, because appropriate equipment is available while the chances of continuous hormonal monitoring are rather limited.  相似文献   
59.
Conflicting results have been published on the shape of the curve relating the change in lung ventilation to the change in alveolar or arterial PCO2 induced by increased inspired CO2 (the CO2 sensitivity). In this study eight human subjects with in-dwelling arterial cannulae were each exposed to five different levels of increased inspired CO2 (1-5%). Arterial PCO2 and ventilation were measured in the 7th minute of each period of CO2 exposure. Each CO2 exposure period was flanked by control periods in which similar measurements were carried out during air breathing. We found non-linear increases in both ventilation and arterial PCO2 with increasing levels of inspired CO2. When 5% CO2 in air was inspired the arterial PCO2 increased by about 15% of the inspired CO2 load. There was no significant non-linearity in the relation between change in alveolar ventilation (normalized to body surface) and change in arterial PCO2. The inter-individual variation in CO2 sensitivity was less when alveolar ventilation was normalized to the CO2 output rather than to body surface area. We conclude that the sensitivity to CO2 is close to constant within the range 0-5% CO2 in the inspired gas.  相似文献   
60.
Summary Modification of a type of end-to-side anastomosis that has been described before is studied. The recipient artery is occluded for only 3–4 minutes to complete the anastomosis by using only the running suture. The anastomotic site was studied by inspection and Scanning Electron Microscope (SEM) at different times after the operation on 30 rats.  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