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   3840篇
  免费   166篇
  国内免费   9篇
耳鼻咽喉   22篇
儿科学   59篇
妇产科学   44篇
基础医学   442篇
口腔科学   135篇
临床医学   261篇
内科学   1085篇
皮肤病学   58篇
神经病学   255篇
特种医学   138篇
外科学   564篇
综合类   21篇
预防医学   82篇
眼科学   10篇
药学   330篇
中国医学   5篇
肿瘤学   504篇
  2023年   25篇
  2022年   52篇
  2021年   92篇
  2020年   32篇
  2019年   40篇
  2018年   84篇
  2017年   44篇
  2016年   40篇
  2015年   71篇
  2014年   91篇
  2013年   105篇
  2012年   174篇
  2011年   159篇
  2010年   90篇
  2009年   92篇
  2008年   164篇
  2007年   163篇
  2006年   174篇
  2005年   178篇
  2004年   162篇
  2003年   169篇
  2002年   175篇
  2001年   102篇
  2000年   129篇
  1999年   112篇
  1998年   50篇
  1997年   40篇
  1996年   48篇
  1995年   44篇
  1994年   42篇
  1993年   31篇
  1992年   100篇
  1991年   96篇
  1990年   80篇
  1989年   79篇
  1988年   96篇
  1987年   65篇
  1986年   72篇
  1985年   74篇
  1984年   40篇
  1983年   54篇
  1981年   20篇
  1979年   28篇
  1977年   24篇
  1975年   15篇
  1974年   15篇
  1973年   17篇
  1972年   20篇
  1971年   15篇
  1967年   17篇
排序方式: 共有4015条查询结果,搜索用时 31 毫秒
1.
Objectives: To examine the factors associated with increase in lumbar spine bone mineral density (LS-BMD) by bisphosphonates (BPs) with active vitamin D analog (aVD).

Methods: Two independent postmenopausal osteoporotic patients treated by BPs with aVD for 24 months (Study 1: n?=?93, Study 2: n?=?99) were retrospectively analyzed.

Results: In Study 1, LS-BMD of the patients significantly increased for 24 m (5.4%, p?r2: 0.088, p?=?.02). While average sCa of the patients was 9.2?mg/dL before treatment, it increased time-dependently to 9.6?mg/dL for 24 m by treatment. As each patient had their LS-BMD five times during the study, there were four instances of %LS-BMD in each patient, resulting in 372 instances of %LS-BMD in Study 1. The smallest Akaike’s information criterion value for the most appropriate cut-off levels of sCa for %LS-BMD by treatment every 6 m was 9.3?mg/dL. The %LS-BMD by treatment for 6 m during 24 m period in patients with sCa ≥9.3?mg/dL (1.5%) was significantly higher than that in patients with sCa <9.3?mg/dL (0.8%, p?=?.038). The results of Study 2 were similar to those of Study 1, confirming the phenomena observed.

Conclusion: sCa was associated with an increased LS-BMD by BPs with aVD.  相似文献   
2.

Objective

This study assessed the association between the timing of first epinephrine administration (EA) and the neurological outcomes following out-of-hospital cardiac arrests (OHCAs) with both initial shockable and non-shockable rhythms.

Methods

This was a post-hoc analysis of a multicenter prospective cohort study (SOS-KANTO 2012), which registered OHCA patients in the Kanto region of Japan from January 2012 to March 2013. We included consecutive adult OHCA patients who received epinephrine. The primary result included 1-month favorable neurological outcomes defined as cerebral performance category (CPC) 1 or 2. Secondary results included 1-month survival and return of spontaneous circulation (ROSC) after arrival at the hospital. Multivariable logistic regression analysis determined the association between delay per minute of the time from call to first EA in both pre- or in-hospital settings and outcomes.

Results

Of the 16,452 patients, 9344 were eligible for our analyses. In univariable analysis, the delay in EA was associated with decreased favorable neurological outcomes only when the initial rhythm was a non-shockable rhythm. In multivariable analyses, delay in EA was associated with decreased ROSC (adjusted odds ratio [OR] for one minute delay, 0.97; 95% confidence interval [CI], 0.96–0.98) and 1-month survival (adjusted OR, 0.95; 95% CI, 0.92–0.97) when the initial rhythm was a non-shockable rhythm, whereas during a shockable rhythm, delay in EA was not associated with decreased ROSC and 1-month survival.

Conclusions

While assessing the effectiveness of epinephrine for OHCA, we should consider the time-limited effects of epinephrine. Additionally, consideration of early EA based on the pathophysiology is needed.  相似文献   
3.
Neurosonography by advanced transvaginal sonography has revealed normal and abnormal intracranial morphology. Transvaginal 3D sonography demonstrates bony structures, multiplanar analysis of inside detailed morphology, tomographic ultrasound imaging in any cutting sections, 3D sonoangiography and volume calculation of ventricles and/or intracranial lesions. Longitudinal assessment of normal and abnormal CNS development is easy by serial scanning. However, the transvaginal approach has several limitations due to its observation by use of a high-frequency transducer from the fetal parietal region. Evaluation of the brainstem and posterior fossa, which are located far from the parietal ultrasound windows of the anterior fontanelle or sagittal suture, is sometimes hard by transvaginal sonography. Visualization of bilateral temporal areas is getting difficult with advanced gestational weeks because of bilateral acoustic shadows due to ossification of parietal bones. Demonstration of frontal/occipital areas is sometimes impossible in late pregnancy due to scan-angle limitation of the transvaginal transducer. From our experiences, the main difference between transvaginal 3D ultrasound and MRI is demonstration of the whole gyral and sulcal formation and brainstem in the late second and third trimesters. Although MRI is a useful modality which can compensate for pitfalls of transvaginal 3D ultrasound, 3D ultrasound is sometimes superior to MRI in detecting cysts in cyst and intracranial calcification. Transvaginal 3D ultrasound is much superior to MRI in detecting bony structures and angioarchitectonics and in volumetric assessment. Regarding objective and accurate prenatal diagnosis, any less-invasive modalities can be used. After considering each advantage and disadvantage of transvaginal 3D ultrasound and MR imaging, it is suggested to use the different technologies according to what is to be detected and evaluated.  相似文献   
4.
We describe a case of 41-year-old Japanese man with Crohn's ileocolitis and cytomegalovirus infection, confirmed by histology of ileal ulcers. Although his colonoscopic and radiological features resembled those of intestinal tuberculosis, granulomas of typical Crohn's disease were evident on histology of biopsy specimens taken from the duodenum and colon. The lesions remain unchanged even after 1.5 years by oral administration of salazosulphapyridine 3g daily.  相似文献   
5.
AIM: To investigate the participation of adenosine receptors in the adenosine 5'-triphosphate (ATP)-induced relaxation in the corpus cavernosum penis (CCP) of rabbits. METHODS: The ATP-induced relaxation was assessed on the noradrenaline precontracted CCP of rabbits in the presence and absence of 8-(3-chlorostyryl)caffeine (CSC); an adenosine A(2A) receptor antagonist; alloxazine and MRS1754; adenosine A(2B) receptor antagonists; and ARL67156, an inhibitor of ecto-nucleoside triphosphate diphosphohydrolases. RESULTS: Adenosine and ATP relaxed the noradrenaline precontracted CCP of rabbits in a concentration-dependent manner. The adenosine- and ATP-induced relaxations were suppressed by alloxazine and MRS1754, but not by 8-(3-chlorostyryl)caffeine. ARL67156 potentiated the ATP-induced relaxation but not the adenosine-induced one. MRS1754 suppressed the ATP-induced relaxation potentiated by ARL67156. CONCLUSIONS: The above results suggest that, in the CCP of rabbits, the adenosine receptor mediating adenosine-induced relaxation is of the A(2B) receptor and the ATP directly causes relaxation through the A(2B) receptor on the CCP.  相似文献   
6.
Histamine-type 2 antagonists (H2-blockers) as represented by cimentidine have been shown to adversely affect renal allograft function, particularly when coadministered with cyclosporine, currently a major immunosuppressant. To determine whether or not a newer and more powerful H2-blocker, famotidine, would produce similar adverse effects, we assessed seven cyclosporine-treated renal allograft recipients with regard to changes in their renal function on or off the H2-blocker over a one-week period. Neither the administration nor withdrawal of famotidine (20–40 mg/day) resulted in any significant changes in serum creatine, BUN, urine output or cyclosporine trough levels, suggesting that famotidine can be safely administered as an H2-blocker to cyclosporine-treated renal allograft recipients.  相似文献   
7.
8.
9.
A 68-year-old man developed right homonymous hemianopic paracentral scotomas from acute infarction of the left extrastriate area. He was studied over the ensuing 12 months with visual fields, conventional MRI, functional MRI (fMRI), and diffusion tensor imaging (DTI). As the visual field defect became smaller, fMRI demonstrated progressively larger areas of cortical activation. DTI initially showed that the lesioned posterior optic radiations were completely interrupted. This interruption lessened in time and had disappeared by one year after onset. fMRI and DTI are innovative measures to follow functional and structural recovery in the central nervous system. This is the first reported application of these imaging techniques to acute cerebral visual field disorders.  相似文献   
10.
1. The relative proportions of beta 1- and beta 2-adrenoceptors were determined by radioligand binding studies in three different rat myocardial preparations: membranes prepared from rat ventricle (ventricular membranes), membranes prepared from rat isolated ventricular myocytes (myocyte membranes), and myocytes isolated from rat ventricle (myocytes). 2. Competition experiments using CGP 20712A or ICI 118,551 with [125I]-iodocyanopindolol ([125I]-ICYP) revealed high- and low-affinity binding sites in ventricular membranes. The concentration at which each beta-antagonist occupied 100% of its high-affinity binding sites was 300 nM for CGP 20712A (beta 1-adrenoceptor) and 50 nM for ICI 118,551 (beta 2-adrenoceptor). 3. The density of high-affinity (beta 1-adrenoceptor) and low-affinity (beta 2-adrenoceptor) binding sites for CGP 20712A was measured by a saturation experiment using [125I]-ICYP in the presence and absence of 300 nM CGP 20712A. In ventricular membranes, the proportions of high-affinity and low-affinity binding sites for CGP 20712A were 73% and 27%, respectively, whereas in myocyte membranes, the corresponding figures were 90% and 10%, respectively. The density of low-affinity binding sites for CGP 20712A in ventricular membranes, defined as [125I]-ICYP-specific binding in the presence of 300 nM CGP 20712A, was decreased by addition of 50 nM ICI 118,551, whereas that in myocyte membranes was not affected. 4. In myocytes, specific binding of [125I]-ICYP and [3H]-CGP 12177 was not detected by saturation experiments performed in the presence of 300 nM CGP 20712A.(ABSTRACT TRUNCATED AT 250 WORDS)  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