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   34211篇
  免费   1835篇
  国内免费   218篇
耳鼻咽喉   199篇
儿科学   723篇
妇产科学   564篇
基础医学   4249篇
口腔科学   767篇
临床医学   2267篇
内科学   9158篇
皮肤病学   630篇
神经病学   2770篇
特种医学   1328篇
外科学   5771篇
综合类   207篇
一般理论   1篇
预防医学   806篇
眼科学   460篇
药学   2445篇
  4篇
中国医学   69篇
肿瘤学   3846篇
  2023年   196篇
  2022年   347篇
  2021年   725篇
  2020年   378篇
  2019年   494篇
  2018年   692篇
  2017年   519篇
  2016年   645篇
  2015年   719篇
  2014年   883篇
  2013年   1034篇
  2012年   1659篇
  2011年   1872篇
  2010年   1042篇
  2009年   919篇
  2008年   1608篇
  2007年   1923篇
  2006年   1780篇
  2005年   1828篇
  2004年   1758篇
  2003年   1716篇
  2002年   1690篇
  2001年   1057篇
  2000年   985篇
  1999年   978篇
  1998年   486篇
  1997年   390篇
  1996年   398篇
  1995年   294篇
  1994年   245篇
  1993年   258篇
  1992年   600篇
  1991年   532篇
  1990年   559篇
  1989年   495篇
  1988年   471篇
  1987年   462篇
  1986年   399篇
  1985年   405篇
  1984年   296篇
  1983年   208篇
  1979年   221篇
  1978年   150篇
  1977年   144篇
  1974年   136篇
  1971年   138篇
  1970年   133篇
  1969年   130篇
  1968年   141篇
  1967年   144篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
We evaluated whether we could predict the neurologic outcome in 55 out-of-hospital cardiac arrest patients using auditory brainstem responses (ABR). ABR patterns were classified into one of 3 types by evaluation of 5 components: type 1, with all 5 components; type 2, lack of at least one response between the 2nd and 5th components; type 3, with only the first component or no response. The relation between the ABR patterns on the 3rd day following resuscitation and the neurologic outcome on hospital discharge was evaluated. The specificity that the 5 awake patients had type-1 ABR was 38%. The sensitivity that the 10 brain dead patients had type-3 ABR was 60%. In the type-1 ABR patients, the negative predictive value that the patients were awake was 100%. In the type-3 ABR patients, the negative predictive value that the patients became brain dead was 90.9%. These results suggest that ABR on the 3rd post-resuscitation day may not be useful for predicting if patients are awake or become brain dead, although the loss of components may be a sign of morbidity, and the presence of the 2nd or later components indicates possible future prevention of brain death.  相似文献   
12.
13.
14.
The Carpentier-Edwards pericardial bioprosthesis has been markedly improved in the long-term results and valve-related complications including valve dysfunction, compared to the previous generation bioprosthesis. We report a patient in whom transient prosthetic valve regurgitation and hemolysis occurred early after mitral valve replacement using a Carpentier-Edwards pericardial bioprosthesis and were resolved by preservative therapy. The patient was a 77-year-old female diagnosed with severe mitral valve stenosis and insufficiency. She underwent mitral valve replacement with a Carpentier-Edwards pericardial bioprosthesis. Opening and closing of the three leaflets looked good on intraoperative transesophageal echocardiography (TEE). The only prosthetic valve regurgitation was evident at the central region where the leaflets form coaptation, and no abnormal findings were seen. Serum lactate dehydrogenase (LDH) was decreased to 405 U/l after surgery. However, LDH again began to increase on the 3rd day after surgery and it increased to 1,830 U/l on the 14th day after surgery. Hemolytic urine was detected on 10th day after surgery. PVL was not detected, but moderate abnormal regurgitation from the outside of the stent pocket was detected on TEE. Revision of valve replacement was considered, but LDH thereafter to 393 U/l on 41st day after surgery. The TEE was repeated, and only a trace of central jet was detected without abnormal regurgitation, unlike the previous examination. The patient did not develop any complications thereafter and was discharged on 47th day after surgery. LDH was nearly normal at the time of discharge.  相似文献   
15.
16.
17.
18.
Background/purpose: It is crucial to establish an accurate method for measuring skin pigmentation in cosmetic science and clinical dermatology. Here, we report a non-invasive precise method for measuring skin melanin content.
Methods: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert–Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method.
Results: A multiple regression analysis with an absorption spectrum of 500–700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards.
Conclusions: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation.  相似文献   
19.
Thyroid function tests were studied in 105 severely disabled children. Fifty-four cases (53%) showed following abnormalities. Serum TSH concentration was increased in 2 cases. Both serum T4 and T3 levels were decreased in 18 cases (17%). Only the serum T4 level was decreased in 25 cases (24%). Only the serum T3 level was decreased in 10 cases (9.5%). Two patients showed primary hypothyroidism. Two patients (monozygotic twins) were suspected to have subclinical hypothalamic-pituitary hypothyroidism caused by septo-optic-dysplasia. Abnormal thyroid functions were caused by anticonvulsants in most patients. The serum T4 level was correlated with the number of anticonvulsants, but not correlated with motor performance (daily activity) or feeding function. Four patients who had low T4 level or low T4 and T3 levels were received L-thyroxine supplementation, but no clinical improvement was observed. The serum TSH concentration was decreased and the TRH test showed hyporeaction in all of these cases. The low T3 level and normal T4 level were not related to anticonvulsant administration. Two of these patients were in poor nutritional condition, resulting in so called low T3 syndrome.  相似文献   
20.
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