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   26096篇
  免费   1490篇
  国内免费   72篇
耳鼻咽喉   226篇
儿科学   716篇
妇产科学   520篇
基础医学   3348篇
口腔科学   805篇
临床医学   1806篇
内科学   6830篇
皮肤病学   614篇
神经病学   2472篇
特种医学   770篇
外科学   3454篇
综合类   130篇
一般理论   9篇
预防医学   1834篇
眼科学   731篇
药学   1380篇
中国医学   74篇
肿瘤学   1939篇
  2023年   208篇
  2022年   330篇
  2021年   821篇
  2020年   462篇
  2019年   646篇
  2018年   958篇
  2017年   626篇
  2016年   645篇
  2015年   801篇
  2014年   940篇
  2013年   1283篇
  2012年   1849篇
  2011年   1858篇
  2010年   1103篇
  2009年   1015篇
  2008年   1647篇
  2007年   1652篇
  2006年   1613篇
  2005年   1458篇
  2004年   1266篇
  2003年   1202篇
  2002年   1121篇
  2001年   331篇
  2000年   263篇
  1999年   394篇
  1998年   185篇
  1997年   152篇
  1996年   134篇
  1995年   133篇
  1994年   122篇
  1993年   104篇
  1992年   179篇
  1991年   198篇
  1990年   158篇
  1989年   161篇
  1988年   140篇
  1987年   140篇
  1986年   109篇
  1985年   108篇
  1984年   105篇
  1983年   82篇
  1982年   64篇
  1981年   77篇
  1979年   80篇
  1978年   68篇
  1977年   49篇
  1976年   79篇
  1974年   48篇
  1973年   60篇
  1971年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
The relationship of IQ (measured by WAIS and all its subscales) and EEG broad band spectral parameters were studied in 40 right-handed, male volunteers ranging in age from 20 to 25 years old. EEGs were recorded in 20 derivations during rest with eyes opened. The results obtained reveal positive and negative correlations with abundant frontal participation in all bands. Mean frequency data show a frequency shift in a very narrow range suggesting that more relations in narrow band could be achieved. These results highlight the need of psychological tests that measure more homogeneous abilities and finer measurement technique to reveal clearly explainable correlations and demonstrate that EEG recordings do reflect intellectual abilities.  相似文献   
113.
Many of the unsatisfactory results in cosmetic surgery are due not to the technique employed itself but to the virtual changes that our work has imposed in other areas. These changes are especially evident in the face, due to the small dimensions of its organs. The surgeon should do a thorough evaluation of the area to be treated prior to the surgery and make her/him notice not only the usual existing asymmetries, but also the modifications which probably will be noticed in the neighboring parts after surgery, to avoid later problems. The surgeon will discover then the many irregularities a patient may have, which have not been noticed by the patient before. These, if not detected in time, are weapons that may act as a boomerang against the surgeon later.  相似文献   
114.
115.
116.
The present work evaluates the cytotoxic, genotoxic, and antimutagenic effects of Phyllanthus orbicularis (plant of genus Phyllantus) aqueous extract in Chinese hamster ovary (CHO) cells. P. orbicularis aqueous extracts are used in Cuban traditional medicine for their antiviral activity against Hepatitis B virus and A and B flu virus. The cytotoxicity of the extract was tested by means of colony-forming ability and growth-inhibition assays as well as by measuring the mitotic index. Apoptosis induction and cell-cycle kinetics were analyzed by cytofluorimetric methods. Chromosome aberration assays were performed to study the genotoxic and antimutagenic activity of the extract. Results show that doses of up to 100 microg/ml of the extract did not induce any cytotoxic effects. Cell survival and mitotic index decreased significantly at doses higher than 100 microg/ml as a function of dose as well as of treatment time. Moreover, continuous treatments of up to 18 h induced the appearance of a significant number of apoptotic cells. Following a 3-h exposure to a dose of 750 microg/ml, cells accumulated significantly in G(2)-M phase and remained blocked in G(1-) and G(2)-M phases after several posttreatments in fresh growth medium. The aqueous extract alone did not induce chromosome aberrations but, in combined treatment with H(2)O(2), significantly reduced H(2)O(2)-induced chromosome aberrations. Flow cytometric analysis of DCFH intracellular oxidation showed that the extract decreased the oxidizing power of H(2)O(2.) This ability could possibly explain the extract's antigenotoxic activity. Absence of cytotoxicity at the lower tested doses and the antimutagenic properties of the extract stimulate the interest in studying possible new pharmaceutical uses of P. orbicularis.  相似文献   
117.
We studied the time course of three electrophysiologic effects of propranolol after intravenous and oral administration and their relationship with plasma levels within the same subjects. Ten patients who had undergone cardiac catheterization for diagnostic purposes received 0.1 mg/kg of propranolol intravenously. Blood was drawn at intervals for 12 hr and heart rate and the effective refractory periods of the atrium (ERPA) and the atrioventricular node (ERPAVN) were determined at the same time. Eight patients continued treatment with propranolol by the oral route for up to 4 days (40 mg every 12 hr). Blood was sampled after each morning dose. Plasma concentrations of propranolol were measured by gas chromatography. Maximal lengthening of ERPA after propranolol (15.1% i.v. and 9.4% oral) was much less marked than that of ERPAVN (23.2% i.v. and 19.4% oral). Heart rate decreased 23.5% (i.v.) and 13.1% (oral). Effects were seen much sooner after intravenous (5-8 min) than after oral administration (86-146 min), but they lasted about twice as long after oral as after intravenous treatment.  相似文献   
118.
Sonographic patterns of Caroli's disease: report of 5 new cases.   总被引:1,自引:0,他引:1  
We have reviewed 5 cases of Caroli's disease, studied from 1982 to 1987, in order to define the validity of its sonographic signs. The "intraluminal portal vein" sign, found in all the cases, is emphasized. This sign may be easily identified and it is never encountered in other diseases. Recessive polycystic kidney disease was present in 3 cases, and congenital hepatic fibrosis was demonstrated in the 2 cases studied by liver biopsy.  相似文献   
119.
The Kleine-Levin syndrome (KLS) is characterized by periodic, sudden-onset episodes of hypersomnia, compulsive hyperphagia, and behavioral-emotional disorders (typically indiscriminate hypersexuality, irritability, impulsive behaviors), lasting from a few days to a few weeks, with almost complete remission in the intercritical periods. Depression, confusion, and thought disorders are frequently associated with the critical symptomatology, and they may suggest other psychiatric diagnoses (schizophrenia, mood disorder, conversion disorder) or a substance abuse. A diencephalic-hypothalamic dysfunction is suspected, even if this composite symptomatology cannot easily be linked to a simple mechanism. The aim of this article is to illustrate problems in differential diagnosis, using a case approach. History, course, and therapeutic intervention in a 21-year-old patient with KLS, associated with a clear psychiatric symptomatology and a critical affective pattern, is reported. Psychiatric correlates of KLS are discussed, including the relationship with affective disorders and the possible emotional impact of the attacks. Implications regarding a combined psychological and pharmacological treatment are also discussed.  相似文献   
120.
Medically unexplained physical symptoms are frequently endorsed by children and adolescents in both clinical and community samples. The aim of this exploratory study is to examine the prevalence of somatic symptoms in a sample of 162 Italian children and adolescents consecutively referred to a Division of Child Neurology and Psychiatry from emotional and/or behavioral disorders. The role of age, gender, and psychiatric status was considered as a variable. Each patient received a DSM-IV assessment, including a diagnostic structured interview (DICA-R). The sample was divided according to gender (96 males, 66 females), age (70 children younger and 92 adolescents older than 12 years), and psychiatric diagnosis (Anxiety, Depression, Depression/Anxiety, Other). The presence of medically unexplained somatic symptoms was based on the responses to the DICA-R. Somatic complaints were reported in 69.2% of the patients. Headache was the most frequent somatic symptom (50.6%). Younger children showed higher rates of abdominal complaints than adolescents. No gender differences in frequency of somatic complaints were reported. Subjects with anxiety and/or depression reported significantly higher rates of somatic complaints, namely headache, than subjects with other mental disorders. No differences in frequency of somatic symptoms were evident between patients with anxiety, depression, and comorbid anxiety-depression. Our data suggest that an unexplained somatic symptom can be often considered as indicative of a neglected anxiety and/or depressive disorder. A collaboration between primary care physicians, pediatricians, and child psychiatrists may promote early diagnoses and timely treatments and prevent negative social and scholastic consequences.  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