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   2186篇
  免费   124篇
  国内免费   5篇
耳鼻咽喉   18篇
儿科学   131篇
妇产科学   48篇
基础医学   236篇
口腔科学   67篇
临床医学   160篇
内科学   567篇
皮肤病学   49篇
神经病学   76篇
特种医学   440篇
外科学   169篇
综合类   53篇
预防医学   59篇
眼科学   22篇
药学   85篇
  1篇
肿瘤学   134篇
  2023年   19篇
  2022年   22篇
  2021年   24篇
  2020年   21篇
  2019年   22篇
  2018年   24篇
  2017年   35篇
  2016年   27篇
  2015年   30篇
  2014年   60篇
  2013年   57篇
  2012年   62篇
  2011年   65篇
  2010年   54篇
  2009年   80篇
  2008年   61篇
  2007年   74篇
  2006年   63篇
  2005年   57篇
  2004年   68篇
  2003年   52篇
  2002年   41篇
  2001年   46篇
  2000年   34篇
  1999年   39篇
  1998年   99篇
  1997年   91篇
  1996年   91篇
  1995年   77篇
  1994年   49篇
  1993年   65篇
  1992年   29篇
  1991年   17篇
  1990年   32篇
  1989年   65篇
  1988年   55篇
  1987年   56篇
  1986年   63篇
  1985年   84篇
  1984年   44篇
  1983年   36篇
  1982年   30篇
  1981年   33篇
  1980年   41篇
  1979年   5篇
  1978年   21篇
  1977年   25篇
  1976年   22篇
  1975年   20篇
  1965年   5篇
排序方式: 共有2315条查询结果,搜索用时 0 毫秒
41.
OBJECTIVE: Most neonatologists include an apnea-free period in the criteria for the discharge of preterm infants. However, the length of time one should wait after the cessation of apnea before sending an infant home without a monitor is debated. We undertook this study in an attempt to define a minimal and safe observation period between the time of the last apnea episode and discharge. METHODS: We reasoned that in infants with idiopathic apnea of prematurity, the intervals between days on which apnea occurs gradually increase until some point at which clinically significant apnea ceases. Therefore, knowledge about the intervals between days on which apnea occurred just before the last apnea would provide a reasonable estimate of the minimal safe observation interval between the last apnea and discharge. We reviewed the charts of 266 infants born in 1993 and 1994 at 相似文献   
42.
43.
The present study investigated the effects of dietary oltipraz on cigarette smoke-related lipophilic DNA adduct formation. Female Sprague- Dawley rats were exposed daily to sidestream cigarette smoke in a whole- body exposure chamber 6 h/day for 4 consecutive weeks. One group of rats was maintained on control diet while another group received the same diet supplemented with either a low (167 p.p.m.) or high (500 p.p.m.) dose of oltipraz, starting 1 week prior to initiation of smoke exposure until the end of the experiment. Analysis of lipophilic DNA adducts by the nuclease P1-mediated 32P-post-labeling showed up to five smoke-related adducts. Adduct no. 5 predominated in both the lung and the heart while adduct nos 3 and 2 predominated in the trachea and bladder, respectively. Quantitative analysis revealed that the total adduct level was the highest in lungs (270+/-68 adducts/10(10) nucleotides), followed by trachea (196+/-48 adducts/10(10) nucleotides), heart (141+/-22 adducts/10(10) nucleotides) and bladder (85+/-16 adducts/10(10) nucleotides). High dose oltipraz treatment reduced the adduct levels in lungs and bladder by >60%, while the reduction in lungs in the low-dose group was approximately 35%. In trachea, the effect of low and high dietary oltipraz on smoke DNA adduction was equivocal, while smoke-related DNA adducts in the heart were minimally inhibited by high-dose oltipraz. In a repeat experiment that employed a 3-fold lower dose of cigarette smoke, oltipraz (500 p.p.m.) was found to inhibit the formation of DNA adducts in rat lungs and trachea by 80 and 65%, respectively. These data clearly demonstrate a high efficacy of oltipraz in inhibiting the formation of cigarette smoke-induced DNA adducts in the target tissues.   相似文献   
44.
RA Dr. U. Baur 《Der Gyn?kologe》2004,37(11):1055-1056
  相似文献   
45.
Some of the girls who live in Germany and have Muslim parents are threatened by female genital mutilation. This report describes the kinds and medical consequences of female genital mutilation as well as the criminal judgement. Female genital mutilation is considered as dangerous bodily harm, not as grievous bodily harm. Consent does not justify the infringement of rights. The argument that Islam justifies the infringement of rights is irrelevant by law. The human right of bodily intactness has priority over the right of religious freedom. Finally the legal regulations about dealing with personal data are presented. A legal compulsory registration still does not exist.  相似文献   
46.
Intraosseous schwannoma (neurilemmoma) is an extremely rare, benign neoplasm, constituting less than 0.2% of primary bone tumors. It infrequently involves the bones of the hand. We present a case of intraosseous neurilemmoma of the metacarpal. Received: 26 July 1999 Revision requested: 16 August 1999 Revision received: 16 September 1999 Accepted: 4 October 1999  相似文献   
47.
This research focuses on the development of enteric microparticles of lansoprazole in a single step by employing the spray drying technique and studies the effects of variegated formulation/process variables on entrapment efficiency and in vitro gastric resistance. Preliminary trials were undertaken to optimize the type of Eudragit and its various levels. Further trials included the incorporation of plasticizer triethyl citrate and combinations of other polymers with Eudragit S 100. Finally, various process parameters were varied to investigate their effects on microparticle properties. The results revealed Eudragit S 100 as the paramount polymer giving the highest gastric resistance in comparison to Eudragit L 100-55 and L 100 due to its higher pH threshold and its polymeric backbone. Incorporation of plasticizer not only influenced entrapment efficiency, but diminished gastric resistance severely. On the contrary, polymeric combinations reduced entrapment efficiency for both sodium alginate and glyceryl behenate, but significantly influenced gastric resistance for only sodium alginate and not for glyceryl behenate. The optimized process parameters were comprised of an inlet temperature of 150°C, atomizing air pressure of 2 kg/cm2, feed solution concentration of 6% w/w, feed solution spray rate of 3 ml/min, and aspirator volume of 90%. The SEM analysis revealed smooth and spherical shape morphologies. The DSC and PXRD study divulged the amorphous nature of the drug. Regarding stability, the product was found to be stable under 3 months of accelerated and long-term stability conditions as per ICH Q1A(R2) guidelines. Thus, the technique offers a simple means to generate polymeric enteric microparticles that are ready to formulate and can be directly filled into hard gelatin capsules.  相似文献   
48.
49.
50.
Alterations in PTH circadian rhythm and PTH target-organ sensitivity exist in adult GH-deficient (AGHD) patients and may underlie the pathogenesis of AGHD-related osteoporosis. GH replacement (GHR) results in increased bone mineral density, but its benefit in AGHD patients over 60 yr old has been debated. To examine the effect of age on changes in PTH circadian rhythm and target-organ sensitivity after GHR, we recruited 22 AGHD patients (12 were <60 yr of age, and 10 were >60 yr of age). Half-hourly blood samples were collected for PTH, calcium, phosphate, nephrogenous cAMP (marker of renal PTH activity), type-I collagenbeta C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker) before and after 1, 3, 6, and 12 months of treatment with GHR. Significant PTH circadian rhythms were present in both age groups throughout the study. After GHR, PTH decreased and nephrogenous cAMP, adjusted calcium, and bone turnover markers increased in both groups, suggesting increased PTH target-organ sensitivity. In younger patients, the changes were significant after 1 month of GHR, but, in older patients, the changes were delayed until 3 months, with maximal changes at 12 months. Older AGHD patients derive benefit from GHR in terms of improvement in PTH sensitivity and bone metabolism. Their response appears delayed and may explain why previous studies have not shown a positive effect of GHR on bone mineral density in older AGHD patients.  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