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   1269323篇
  免费   97167篇
  国内免费   1576篇
耳鼻咽喉   16361篇
儿科学   41155篇
妇产科学   35047篇
基础医学   190388篇
口腔科学   34880篇
临床医学   118609篇
内科学   248647篇
皮肤病学   27379篇
神经病学   103002篇
特种医学   47096篇
外国民族医学   265篇
外科学   179475篇
综合类   25866篇
现状与发展   3篇
一般理论   579篇
预防医学   105470篇
眼科学   28241篇
药学   93184篇
  6篇
中国医学   2034篇
肿瘤学   70379篇
  2018年   13667篇
  2017年   10502篇
  2016年   11473篇
  2015年   13237篇
  2014年   18196篇
  2013年   27738篇
  2012年   37972篇
  2011年   40385篇
  2010年   23311篇
  2009年   22449篇
  2008年   38145篇
  2007年   40794篇
  2006年   40375篇
  2005年   39516篇
  2004年   37970篇
  2003年   36340篇
  2002年   35264篇
  2001年   56217篇
  2000年   57305篇
  1999年   48326篇
  1998年   13505篇
  1997年   12296篇
  1996年   12745篇
  1995年   12000篇
  1994年   11175篇
  1993年   10475篇
  1992年   38352篇
  1991年   37829篇
  1990年   36661篇
  1989年   35386篇
  1988年   32854篇
  1987年   32147篇
  1986年   30636篇
  1985年   28913篇
  1984年   22042篇
  1983年   19277篇
  1982年   11439篇
  1981年   10404篇
  1979年   21013篇
  1978年   15458篇
  1977年   12825篇
  1976年   11878篇
  1975年   12854篇
  1974年   15628篇
  1973年   15400篇
  1972年   14562篇
  1971年   13587篇
  1970年   12814篇
  1969年   12092篇
  1968年   11278篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
A 37-year-old male with history of alcohol abuse presented to us with nausea, vomiting, and abdominal pain with ascites. He was diagnosed with alcoholic liver disease with coagulopathy and pancreatitis. During hospitalization, the patient developed intra-abdominal hemorrhage. He was treated with platelets, packed red blood cells and fresh frozen plasma without any improvement. Following this he was treated with activated recombinant factor VII (90 microg/kg), which resulted in normalization of the prothrombin time and the activated partial thromboplastin time and stabilization of hematocrit within a few hours. We review the current literature on the approved and off-label use of activated recombinant factor VII.  相似文献   
963.
Background Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism. Methods We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences. Results Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up. Conclusions This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.  相似文献   
964.
965.
This article examines evidence-based assessment practices for attention deficit hyperactivity disorder (ADHD). The nature, symptoms, associated features, and comorbidity of ADHD are briefly described, followed by a selective review of the literature on the reliability and validity of ADHD assessment methods. It is concluded that symptom rating scales based on the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994), empirically and rationally derived ADHD rating scales, structured interviews, global impairment measures, and behavioral observations are evidence-based ADHD assessment methods. The most efficient assessment method is obtaining information through parent and teacher rating scales; both parent and teacher ratings are needed for clinical purposes. Brief, non-DSM based rating scales are highly correlated with DSM scales but are much more efficient and just as effective at diagnosing ADHD. No incremental validity or utility is conferred by structured interviews when parent and teacher ratings are utilized. Observational procedures are empirically valid but not practical for clinical use. However, individualized assessments of specific target behaviors approximate observations and have both validity and treatment utility. Measures of impairment that report functioning in key domains (peer, family, school) as well as globally have more treatment utility than nonspecific global measures of impairment. DSM diagnosis per se has not been demonstrated to have treatment utility, so the diagnostic phase of assessment should be completed with minimal time and expense so that resources can be focused on other aspects of assessment, particularly treatment planning. We argue that the main focus of assessment should be on target behavior selection, contextual factors, functional analyses, treatment planning, and outcome monitoring.  相似文献   
966.
We conducted a double blind controlled trial in 28 Duchenne muscular dystrophy (DMD) patients with Deflazacort (DF), an oxazoline derivative of prednisolone which reduces its side-effects. Myometric muscle strength measurements, Scott Score and timed tests showed statistically significant improvement for the treated group (P less than 0.05). Side-effects after 9 months of treatment included mild cushingoid appearance in four patients (28%) and moderate in only one (7%), increased appetite in seven (50%), increased body hair in four (28%), irritability and hyperactivity in three (21%). Increased body weight was not prominent and was controlled with dietary measures. No patient had to be withdrawn from medication. More research and long-term follow-up are needed in order to establish the mechanism of improvement and the consequences of long-term steroid administration in DMD. In this regard DF appears as an alternative to prednisone preserving its benefits but with fewer side-effects.  相似文献   
967.
We examined binding to excitatory amino acid and inhibitory amino acid receptors in frozen hippocampal sections prepared from surgical specimens resected from 8 individuals with medically refractory temporal lobe epilepsy. The excitatory receptors studied included N-methyl-D-aspartate (NMDA), strychnine-insensitive glycine, phencyclidine, and quisqualate. The inhibitory receptors studied were gamma-aminobutyric acid type A (GABAA) and benzodiazepine. Excitatory and inhibitory amino acid receptor binding were differentially altered in the patients with temporal lobe epilepsy in comparison to 8 age-comparable autopsy control subjects, and changes in receptor binding were regionally selective in four areas. Binding to phencyclidine receptors associated with the NMDA channel was reduced by 35 to 70% in all regions in the hippocampi of the patients. In contrast, binding to the NMDA recognition site and its associated glycine modulatory site was elevated by 20 to 110% in the cornu ammonis (CA) 1 area and dentate gyrus of the hippocampus of the patients. Binding to these sites was unaffected in area CA4. Binding to the quisqualate-type excitatory amino acid receptor was unchanged in all regions except the stratum lacunosum moleculare CA1, where it was increased by 63%. GABAA and benzodiazepine receptor binding was reduced by 20 to 60% in CA1 and CA4, but unchanged in dentate gyrus. The data indicate that excitatory and inhibitory amino acid receptors are altered in the hippocampus of patients with temporal lobe epilepsy.  相似文献   
968.
Adult male Wistar rats were either socially isolated or group-housed for 6 weeks and then tested in an elevated plus maze. During isolation the rats received either water or two concentrations of the calcium channel inhibitors, diltiazem or verapamil, in drinking solutions (approximately 5 and 10 mg/kg daily). Isolated rats showed a significantly lower total number of arm entries, a lower percentage of open arm entries and negligible time spent therein than did group-housed animals. Verapamil, in the higher dose, prevented that effect of isolation. Treatment with diltiazem brought about a similar tendency, though the effect did not reach statistical significance. Chronic treatment of group-housed rats with either drug failed to influence their behavior in the plus maze. We conclude that certain calcium channel inhibitors may decrease the behavioral deficit in the elevated plus maze that follows chronic social isolation.  相似文献   
969.
970.
A recent paper in this journal (1) suggests that involving terminally ill patients in choices concerned with Cardio-Pulmonary Resuscitation (CPR) produces 'psychological pain' and therefore is ill-advised. Such a claim rests on anecdotal observations made by the authors. In this paper I suggest that drawing conclusions in ethics, no less than in science, requires a rigorous framework and cannot be relegated to personal observation of a few cases. The paper concludes by suggesting that patients, if we acknowledge their valid interest in making their own choices, must themselves be allowed to make a prior choice about choosing. Those who may not wish to choose may properly be relieved of this burden and may allow another to choose for them. Routinely allowing others to make choices for competent adults, however, is likely to decrease communication with the dying patient and to introduce an atmosphere of suspicion and fear and to exclude the competent patient from his/her rightful place in the community.  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