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   34633篇
  免费   1595篇
  国内免费   156篇
耳鼻咽喉   421篇
儿科学   582篇
妇产科学   585篇
基础医学   4504篇
口腔科学   1268篇
临床医学   2671篇
内科学   8275篇
皮肤病学   808篇
神经病学   2524篇
特种医学   1383篇
外科学   5573篇
综合类   236篇
一般理论   2篇
预防医学   1169篇
眼科学   509篇
药学   2374篇
中国医学   52篇
肿瘤学   3448篇
  2022年   378篇
  2021年   643篇
  2020年   300篇
  2019年   451篇
  2018年   637篇
  2017年   467篇
  2016年   514篇
  2015年   600篇
  2014年   807篇
  2013年   885篇
  2012年   1426篇
  2011年   1522篇
  2010年   860篇
  2009年   796篇
  2008年   1411篇
  2007年   1492篇
  2006年   1533篇
  2005年   1562篇
  2004年   1503篇
  2003年   1423篇
  2002年   1419篇
  2001年   1251篇
  2000年   1408篇
  1999年   1230篇
  1998年   432篇
  1997年   313篇
  1996年   330篇
  1995年   303篇
  1994年   251篇
  1993年   243篇
  1992年   815篇
  1991年   766篇
  1990年   692篇
  1989年   703篇
  1988年   689篇
  1987年   667篇
  1986年   677篇
  1985年   596篇
  1984年   436篇
  1983年   352篇
  1979年   344篇
  1978年   237篇
  1977年   199篇
  1975年   201篇
  1974年   226篇
  1973年   210篇
  1972年   199篇
  1971年   209篇
  1970年   203篇
  1969年   224篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The patients reported in our previous paper were followed further, by analyzing hair samples collected monthly for 4 or 5 months, while growing hair continues to reflect the individual dosage history of haloperidol. In patients in whom the drug had been discontinued, the portion of hair that reflected the change of dose continued to move upward. In hair of patients in whom the dosage was decreased by one-half, the portion of change was also shown to move upward. These results indicate the potential usefulness of hair for assessing the individual past dosage history of haloperidol.  相似文献   
102.
Simple and concise measures for health status are desirable in clinical practice. The Asthma Bother Profile (ABP), which consists of 23 items, has been developed to assess how much asthma bothers patients. The Airways Questionnaire 20 (AQ20) is a simple instrument which consists of 20 items. The purpose of this study was to investigate how the ABP and AQ20 evaluate the health status of patients with asthma. A total of 166 patients with chronic asthma (age: 48 ± 16 yr, 77 males) completed pulmonary function testing, measurement of airway hyperresponsiveness, dyspnea rating, assessments of their anxiety and depression (HADS; Hospital Anxiety and Depression Scale), and assessments of their health status. The health status was assessed using the ABP, AQ20, the short-form 36 health survey questionnaire (SF-36), the Living With Asthma Questionnaire (LWAQ) and the Asthma Quality of Life Questionnaire (AQLQ). The Japanese version of the ABP included only 15 'bother' items out of the original 23 items due to cultural differences. The scores on the ABP were widely distributed, whereas the scores on the AQ20 were skewed towards the milder end of the scale. The ABP had a strong correlation with the Avoidance and Distress constructs on the LWAQ, and Anxiety and Depression on the HADS (Rs = 0.56 ∼ 0.79), and its strongest correlation with the General Health (Rs = - 0.64) scale among the 8 subscales on the SF-36. The AQ20 had a less significant correlation with the LWAQ, AQLQ, and SF-36 than the ABP. The ABP and AQ20 were short and simple to complete, and both measures could easily be used in clinical practice. The ABP can evaluate patients more specifically with respect to distress and bother than the AQ20.  相似文献   
103.
The biologic mechanisms involved in the intratumoral heterogeneous distribution of 18F-FDG have not been fully investigated. To clarify factors inducing heterogeneous 18F-FDG distribution, we determined the intratumoral distribution of 18F-FDG by autoradiography (ARG) and compared it with the regional expression levels of glucose transporters Glut-1 and Glut-3 and hexokinase-II (HK-II) in a rat model of malignant tumor. METHODS: Rats were inoculated with allogenic hepatoma cells (KDH-8) into the left calf muscle (n = 7). Tumor tissues were excised 1 h after the intravenous injection of 18F-FDG and sectioned to obtain 2 adjacent slices for ARG and histochemical studies. The regions of interest (ROIs) were placed on ARG images to cover mainly the central (CT) and peripheral (PT) regions of viable tumor tissues and necrotic/apoptotic (NA) regions. The radioactivity in each ROI was analyzed quantitatively using a computerized imaging analysis system. The expression levels of Glut-1, Glut-3, and HK-II were determined by immunostaining and semiquantitative evaluation. The hypoxia-inducible factor 1 (HIF-1) was also immunostained. RESULTS: ARG images showed that intratumoral 18F-FDG distribution was heterogeneous. The accumulation of 18F-FDG in the CT region was the highest, which was 1.6 and 2.3 times higher than those in the PT and NA regions, respectively (P < 0.001). The expression levels of Glut-1, Glut-3, and HK-II were markedly higher in the CT region (P < 0.001) compared with those in the PT region. The intratumoral distribution of 18F-FDG significantly correlated with the expression levels of Glut-1, Glut-3, and HK-II (r = 0.923, P < 0.001 for Glut-1; r = 0.829, P < 0.001 for Glut-3; and r = 0.764, P < 0.01 for HK-II). The positive staining of HIF-1 was observed in the CT region. CONCLUSION: These results demonstrate that intratumoral 18F-FDG distribution corresponds well to the expression levels of Glut-1, Glut-3, and HK-II. The elevated expression levels of Glut-1, Glut-3, and HK-II, induced by hypoxia (HIF-1), may be contributing factors to the higher 18F-FDG accumulation in the CT region.  相似文献   
104.
In patients with hepatic cirrhosis, the globus pallidus and putamen show high intensity on T1-weighted MRI. While the causes of this high signal have been thought to include paramagnetic substances, especially manganese, no evidence for this has been presented. Autopsy in four cases of hepatic cirrhosis permitted measurement of metal concentrations in brain and histopathological examination. In three cases the globus pallidus showed high intensity on T1-weighted images. Mean manganese concentrations in globus pallidus, putamen and frontal white matter were 3.03 ± 0.38, 2.12 ± 0.37, and 1.38 ± 0.24 (μg/g wet weight), respectively, being approximately four- to almost ten-fold the normal values. Copper concentrations in globus pallidus and putamen were also high, 50 % more than normal. Calcium, iron, zinc and magnesium concentrations were all normal. The fourth case showed no abnormal intensity in the basal ganglia and brain metal concentrations were all normal. Histopathologically, cases with showing high signal remarkable atrophy, necrosis, and deciduation of nerve cells and proliferation of glial cells and microglia in globus pallidus. These findings were similar to those in chronic manganese poisoning. On T1-weighted images, copper deposition shows no abnormal intensity. It is therefore inferred that deposition of highly concentrations of manganese may caused high signal on T1-weighted images and nerve cell death in the globus pallidus. Received: 12 August 1996 Accepted: 17 December 1996  相似文献   
105.
106.
Summary We investigated the frequency of personality disorders (PDs) and the relationship between the pressence of PD and the 4-month outcome of depression under adequate antidepressant therapy in a Japanese sample of 96 outpatients with non-bipolar major depression. The diagnosis of PD was made using a structured interiew method (the Structured Clinical Interview for DSM-III-R Personality Disorders) and after severe depressive symptoms were reduced. Any one kind of PD was found in 54.2% of the saple. The most frequent was avidant (34–4%), obsessived-compulsive (22.9%), narcisstic (18.8%), and dependent (16.7%) PDs. The frequencies of these PDs in our study except narcisstic PD, were about the same as those reported in previous studies with a matched setting for the PD diagnosis. Compared with patients without PD, a worse outcome was found in patients with PD, especially patients with multiple PDs from multiple PD clussters. There was no evidence that a specific PD or PD cluster especially worsens the outcome of depression.  相似文献   
107.
108.
109.
A 75-year-old man was admitted to our hospital with dysesthesia of the right lip, dysphagia and gait disturbance. He presented with right Wallenberg syndrome and brain MR image showed a fresh infarction in the right lateral medulla. Therapy with heparin and ozagrel sodium was started. For a time his symptom improved a little, but after 8 days he developed re-infarction, thrombocytopenia and DIC, while being treated with heparin for cerebral infarction. Heparin was discontinued, and these symptoms improved quickly. The clinical course and the positive anti-platelet factor 4-heparin complex antibody suggested that these symptoms were caused by heparin-induced thrombocytopenia (HIT). HIT should be included as a differential diagnosis for progression of ischemic stroke under heparin therapy.  相似文献   
110.
To find antiviral agents, various sulfonamidobenzophenone oximes (II) were synthesized from the appropriate m-sulfonamidobenzophenones by hydroxylamine reaction. The reaction products were generally obtained as syn/anti mixtures which were separable by fractional crystallization. The anti isomer had more potent antipoliovirus activity than the syn isomer. Various sulfonamidobenzamides (III) which were structurally related to II were synthesized by the reactions of amino-substituted benzamides with sulfuryl chloride or amines with (aminosulfonyl)benzoyl chloride. Antiviral activity was examined by the plaque-inhibition test. Compounds 5, 36, and 69 exhibited strong antipicornavirus activity. The structure-activity relationships are discussed.  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