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   19505篇
  免费   948篇
  国内免费   90篇
耳鼻咽喉   88篇
儿科学   271篇
妇产科学   229篇
基础医学   2520篇
口腔科学   528篇
临床医学   1323篇
内科学   4611篇
皮肤病学   269篇
神经病学   1688篇
特种医学   985篇
外科学   3927篇
综合类   75篇
预防医学   496篇
眼科学   360篇
药学   1464篇
中国医学   46篇
肿瘤学   1663篇
  2023年   85篇
  2022年   184篇
  2021年   369篇
  2020年   160篇
  2019年   247篇
  2018年   363篇
  2017年   274篇
  2016年   304篇
  2015年   306篇
  2014年   418篇
  2013年   545篇
  2012年   827篇
  2011年   942篇
  2010年   489篇
  2009年   426篇
  2008年   775篇
  2007年   915篇
  2006年   939篇
  2005年   894篇
  2004年   832篇
  2003年   809篇
  2002年   816篇
  2001年   776篇
  2000年   790篇
  1999年   725篇
  1998年   241篇
  1997年   202篇
  1996年   165篇
  1995年   136篇
  1994年   131篇
  1993年   145篇
  1992年   524篇
  1991年   464篇
  1990年   435篇
  1989年   431篇
  1988年   416篇
  1987年   356篇
  1986年   355篇
  1985年   356篇
  1984年   200篇
  1983年   165篇
  1982年   83篇
  1979年   169篇
  1978年   124篇
  1977年   91篇
  1974年   124篇
  1973年   113篇
  1972年   81篇
  1970年   83篇
  1969年   101篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Tumor tissue from 57 cases of keratinizing-type squamous cell carcinoma of the uterine cervix that had been stored in the archives of Osaka City University Hospital between May 1986 and October 1994 were stained with periodic acid-Schiff (PAS) reagent following amylase and alcian blue to identify the presence of intracellular mucin and to assess the value and significance of demonstrating the presence of mucin. Nineteen specimens (33.3%) stained positive for mucin with alcian blue or PAS following diastase. The results of mucin staining were not significant in terms of survival by Kaplan-Meier's analysis.  相似文献   
992.
993.
Objective: This study aimed to examine the quality of life (QOL) in Japanese couples during the transition to parenthood with their first child.

Background: Relevant literature suggests that the health status of women drop during pregnancy and the postpartum period. However, less is known about their partner’s well-being during the transition to parenthood and little research has addressed the relationship between couples’ QOL across multiple domains.

Method: Participants included 9216 married Japanese men and women, including 3729 couples, who were expecting or raising their first child under the age of three. They independently completed questionnaires on baseline demographics and on WHOQOL-BREF.

Results: Men showed higher scores for psychological QOL, while women had higher scores for social and environment QOL. A significant interaction between gender and stage of transition to parenthood was found. The moderating effect of age between the stage and QOL was found for men on the physical and psychological domains. Couples’ QOL scores were weakly to moderately correlated.

Conclusion: Findings suggest that both men and women had lower QOL, with the exception of women’s physical QOL, after childbirth, but they showed different trends during the transition to parenthood across different domains of QOL.  相似文献   

994.
OBJECTIVE: The aims of this study were to prove the presence of transient phrenic nerve palsy in children after cardiac surgery by successive recordings of diaphragmatic action potentials (DAPs), and to decide the indication of diaphragmatic plication in infants with postoperative phrenic nerve palsy. METHODS: The DAPs were recorded from 11 infants (age 0-54 months) under artificial ventilation after cardiac surgery. The successive DAP recordings were performed within 3-4 days (0W), 1 week (1W) and 2 weeks (2W) after operation to make a final decision for diaphragmatic plication to wean artificial ventilation. RESULTS: The patients were divided into 3 groups according to the DAP changes in successive recordings, namely, patients with normal DAPs at 0W, patients with transient depression of DAPs at 0W followed by recovery to normal DAPs by 1W and/or 2W, and patients with persistent depression of DAPs of the affected side necessitating plication of hemidiaphragm. CONCLUSIONS: In infants with phrenic nerve palsy after cardiothoracic surgery, persistently abnormal DAPs in repeated electrophysiologic examinations for at least 2 weeks after surgery are a useful guidance to support clinical and radiological evidence for an indication of diaphragmatic plication.  相似文献   
995.
The purpose of this study was to determine management guidelines for biopsy‐induced pneumothorax with the assistance of manual aspiration, mainly based on the duration of complicated pneumothorax. Data from 388 consecutive percutaneous needle lung biopsies were examined. Patients with pneumothorax on postbiopsy chest CT images underwent percutaneous manual aspiration with an 18‐G i.v. catheter. Frequency and management of biopsy‐induced pneumothorax and period to its disappearance were reviewed. Postbiopsy pneumothorax occurred in 133 of 388 (34.3%) procedures. Manual aspiration in 72 of these 133 patients was carried out immediately after biopsy. The pneumothorax had resolved completely on follow‐up chest radiographs without chest tube placement in 121 of the 133 pneumothoraces (91.0%). In cases requiring chest tube, the mean period from biopsy until resolution of the pneumothorax was 6.0 ± 5.3 days, but was only 2.4 ± 2.9 days when chest tube placement was not needed. Specifically, time until recovery was short both in those not requiring manual aspiration (2.1 ± 3.4 days) and in those with a pneumothorax that disappeared completely or almost completely after manual aspiration (1.9 ± 2.0 days). The almost equally short recovery periods in patients not requiring manual aspiration and those requiring immediate manual aspiration indicates the value of rapid management.  相似文献   
996.
The ATP-sensitive potassium channel (K+ATP) has been suggested as an important mechanism for the reactivity of vascular smooth muscle. We investigated the effects of K+ channel openers (lemakalim, pinacidil) on hypoxic pulmonary vasoconstriction (HPV) and angiotensin II (Ag II) induced vasoconstriction in isolated rat lungs (Sprague-Dawley rats: 300-450 g). Ventilation with hypoxic gas (2% O2, 5% CO2) was performed for 6 min after the injection of Ag II (0.1 microgram). Isolated lungs were perfused under constant flow (0.04 ml/g/min) using 20 ml of blood from donor rat. The perfusion pressure was used as the pulmonary artery pressure. Lemakalim or pinacidil was pre-administered through the reservoir. Pretreatment with pinacidil (10(-4) M) or lemakalim (10(-5) M) inhibited the pressor response to hypoxia, but did not inhibit the response to angiotensin II. Although the effect of lemakalim on HPV was reversed by administration of glibenclamide (10(-5) M) or tolbutamide (10(-3) M), the effect of pinacidil on HPV was not influenced by either drug. These results suggest that 1) K+ channel openers (lemakalim and pinacidil) inhibit the pressor response to hypoxia, and 2) lemakalim seems to act through K+ATP, whereas pinacidil may have other mechanisms of inhibition of vascular smooth muscle contraction. K+ATP may play an important role in the regulation of pulmonary vascular reactivity to hypoxia.  相似文献   
997.
For intracranial diseases, plasma atrial natriuretic peptide (ANP), antidiuretic hormone (ADH) and aldosterone were determined and their effects on the development of hyponatremia with central origin were studied. The subjects were 71 cases of intracranial diseases which were admitted to our hospital during a period of 1 year from March, 1989 to March, 1990. The diseases were broken down to subarachnoid hemorrhage 26 cases, hypertensive intracerebral hemorrhage 19 cases, head injury 12 cases, cerebral infarction 11 cases and 3 other cases. Serum-urine electrolytes, plasma ANP and ADH were determined in the acute stage on Day 1 to 4, in the hyponatremia stage on Day 5 to 14 and in the chronic stage on Day 15 downward. Hyponatremia was defined as the serum sodium level of 130 mEq/l or less. Cases evidently having other causes such as heart failure and renal insufficiency were excluded. In the normal control group of persons who were admitted to our hospital for a close checkup (n = 20), plasma ANP was 26.5 +/- 11.6 pg/ml (10-50); levels of 50 pg/ml or more were regarded as abnormally high. 1) Hyponatremia was found in 18 cases (25.4%), subarachnoid hemorrhage in 7 cases, hypertensive intracerebral hemorrhage in 4 cases, head injury in 5 cases and others in 2 cases. 2) The time of onset of hyponatremia was on the 8.3 hospital day. The duration was 7.2 days. The minimum serum sodium level was 124.6 mEq/l. 3) There was no significant change in the plasma aldosterone level at each stage.2+ Predicting development of hyponatremia from plasma ADH and ANP levels in the acute stage is difficult. Inadequate secretion of ANP rather than ADH appeared to be an important factor for the development of hyponatremia, but the plasma ANP level was not always abnormally high, so involvement of other sodium diuretic factors should also be kept in mind.  相似文献   
998.
Several studies have suggested that cyclooxygenase-2 (COX-2) plays a role in ischemic neuronal death. Genetic disruption of COX-2 has been shown to reduce susceptibility to focal ischemic injury and N-methyl-d-aspartate-mediated neurotoxicity. The purpose of this study was to examine the effects of COX-2 deficiency on neuronal vulnerability after transient forebrain ischemia. Marked upregulation of COX-2 immunostaining in neurons was observed at the early stage and prominent COX-2 staining persisted in the CA1 medial sector and CA2 sector over 3 days after ischemia. The immunohistologic pattern of COX-2 staining in these sectors gradually condensed to a perinuclear location. The degree of hippocampal neuronal injury produced by global ischemia in COX-2-deficient mice was less than that in wild-type mice, coincident with attenuation of DNA fragmentation in the hippocampus. Also, treatment with a selective COX-2 inhibitor, nimesulide, after ischemia decreased hippocampal neuronal damages. These results of genetic disruption and chemical inhibition of cyclooxygenase-2 show that inhibition of COX-2 ameliorates selective neuronal death after transient forebrain ischemia in mice.  相似文献   
999.
1000.
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