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   2234篇
  免费   79篇
  国内免费   36篇
耳鼻咽喉   10篇
儿科学   80篇
妇产科学   72篇
基础医学   259篇
口腔科学   31篇
临床医学   147篇
内科学   408篇
皮肤病学   63篇
神经病学   263篇
特种医学   95篇
外科学   307篇
综合类   9篇
预防医学   311篇
眼科学   40篇
药学   126篇
中国医学   1篇
肿瘤学   127篇
  2023年   4篇
  2022年   18篇
  2021年   65篇
  2020年   31篇
  2019年   35篇
  2018年   46篇
  2017年   45篇
  2016年   51篇
  2015年   43篇
  2014年   73篇
  2013年   91篇
  2012年   168篇
  2011年   159篇
  2010年   89篇
  2009年   85篇
  2008年   161篇
  2007年   168篇
  2006年   157篇
  2005年   161篇
  2004年   149篇
  2003年   133篇
  2002年   131篇
  2001年   36篇
  2000年   32篇
  1999年   17篇
  1998年   22篇
  1997年   15篇
  1996年   11篇
  1995年   19篇
  1994年   13篇
  1993年   13篇
  1992年   5篇
  1991年   9篇
  1990年   8篇
  1989年   12篇
  1988年   6篇
  1987年   13篇
  1986年   10篇
  1985年   8篇
  1984年   5篇
  1983年   6篇
  1982年   2篇
  1981年   3篇
  1980年   3篇
  1979年   4篇
  1978年   6篇
  1976年   3篇
  1975年   1篇
  1973年   2篇
  1970年   1篇
排序方式: 共有2349条查询结果,搜索用时 15 毫秒
1.

Background

We have recently shown that human epididymis protein 4 (HE4) levels correlate with the severity of cystic fibrosis (CF) lung disease. However, there are no data on how HE4 levels alter in patients receiving CFTR modulating therapy.

Methods

In this retrospective clinical study, 3 independent CF patient cohorts (US-American: 29, Australian: 12 and Irish: 19 cases) were enrolled carrying at least one Class III CFTR CF-causing mutation (p.Gly551Asp) and being treated with CFTR potentiator ivacaftor. Plasma HE4 was measured by immunoassay before treatment (baseline) and 1–6?months after commencement of ivacaftor, and were correlated with FEV1 (% predicted), sweat chloride, C-reactive protein (CRP) and body mass index (BMI).

Results

After 1?month of therapy, HE4 levels were significantly lower than at baseline and remained decreased up to 6?months. A significant inverse correlation between absolute and delta values of HE4 and FEV1 (r?=??0.5376; P?<?.001 and r?=??0.3285; P?<?.001), was retrospectively observed in pooled groups, including an independent association of HE4 with FEV1 by multiple regression analysis (β?=??0.57, P?=?.019). Substantial area under the receiver operating characteristic curve (ROC-AUC) value was determined for HE4 when 7% mean change of FEV1 (0.722 [95% CI 0.581–0.863]; P?=?.029) were used as classifier, especially in the first 2?months of treatment (0.806 [95% CI 0.665–0.947]; P?<?.001).

Conclusions

This study shows that plasma HE4 levels inversely correlate with lung function improvement in CF patients receiving ivacaftor. Overall, this potential biomarker may be of value for routine clinical and laboratory follow-up of CFTR modulating therapy.  相似文献   
2.
BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.  相似文献   
3.
OBJECTIVE: Visual symptoms are common in patients with preeclampsia, and are caused by various underlying pathological changes in the retina. Blurred vision may be one of these symptoms. We describe three cases in which the underlying retinal pathology of blurred vision was clarified using optical coherence tomography (OCT), a novel, non-invasive ophthalmic imaging technique that provides micrometer-scale resolution images of the human retina. METHODS: Three patients with preeclampsia complained of blurred vision postpartum. In all cases, ophthalmoscopy was performed at the bedside, followed by the assessment of best corrected visual acuity, slit-lamp biomicroscopy, fluorescein angiography (FLA), and OCT. In all cases, the presence of central visual defects was examined by an Amsler-grid. RESULTS: In one case, the symptoms were bilateral. In all affected eyes, the patients complained of a relative central scotoma. Ophthalmoscopy showed edema in the affected maculae, while OCT examination clarified a serous neurosensory detachment of the macula. In one case, a neurosensory detachment was also detected in the papillomacular region of a fellow eye with no symptoms. In two cases, FLA was performed, but only in one case could we detect late leakage and subretinal exudates. The serous detachments observed showed total resolution in all cases within 5 to 10 weeks, with restoration of visual acuity. CONCLUSION: In patients with preeclampsia, OCT may provide a useful method for the precise assessment of retinal changes, distinguishing retinal edema from serous neurosensory detachments. This finding may help to clarify the pathophysiological circulatory changes seen in preeclampsia.  相似文献   
4.
Renal excretion of endothelin in children   总被引:1,自引:0,他引:1  
Endothelin (ET) is a peptide with profound vasoconstrictive potential. First isolated from porcine endothelial cell supernatant, it is produced also by smooth muscle, epithelial and circulating cells. Besides vasoconstriction, a wide spectrum of biological activities of ET (via activation of membrane receptors) has been described. These include regulation of other hormones and neurotransmitters, cellular growth and proliferation, bronchoconstriction, and, in the kidney, natriuresis and water diuresis. ET exerts its effects mainly in an autocrine and paracrine fashion. A high concentration of ET is found in urine, compared with plasma originating mainly from the kidney itself. In this review we focus on the role of urinary excretion of ET in children. ET excretion was determined under different physiological and pathological conditions. In premature infants and newborns, the daily excretion of ET (corrected for body surface) was higher than in older children; it was constant, and comparable to the values in healthy adults after the age of 2 years. Renal ET excretion correlated positively with urine flow in both healthy and sick children. Conditions with tubular and/or collecting duct cell damage, such as severe hypoxia, hemolytic-uremic syndrome, renal transplantation, diabetes mellitus, chronic renal failure, and contrast media cytotoxicity were characterized by elevated urinary excretion of ET. In conclusion, the renal excretion of ET is influenced by several factors, probably reflecting the intrarenal ET production. ET has a low specificity with regard to renal injury. Received May 7, 1996; received in revised form January 14, 1997; accepted January 17, 1997  相似文献   
5.
Twenty-four-hour blood pressure and heart rate measurements were carried out in 14 newly diagnosed diabetics and in 28 diabetics with 5–13 years' duration of the disease; 8 healthy children were used as controls. Mean arterial blood pressure increased at night in 5, decreased slightly (less than 10%) in 5 and decreased markedly (more than 10%) in 18 diabetics with longer duration of the disease. The diurnal-nocturnal differences in heart rates were significantly lower in diabetics with relative "nocturnal hypertension" compared to the control group ( p < 0.05). A significant negative correlation was found between maximal arterial blood pressure during physical exercise and the diurnal-nocturnal differences in mean arterial blood pressure in diabetics ( r =−0.58; p < 0.02). In conclusion, we found elevated nocturnal blood pressure in a subgroup of children with longer duration of diabetes and without increased albumin excretion. However, longitudinal studies of blood pressure profiles are needed to identify the candidates for diabetic vasculopathy among diabetic children.  相似文献   
6.
Summary Several components of a system for structure generation are now well developed. HIPPO is a program that characterises a receptor binding site for potential target sites within the cavity that can be used in de novo design. The target sites include simple and complex hydrogen bonds, covalent bonds and bonds to metal ions. The SPROUT program for structure generation consists of two main components: the first is skeleton generation, followed by atom substitution to convert the solution skeletons to molecules. A new method of skeleton generation is presented here, where part skeletons are grown outwards from each target site. The part skeletons are then connected together to form solution skeletons. Finally the CAESA program is described, that ranks the output from SPROUT according to ease of synthesis.  相似文献   
7.
K Jellinek  T Tulassay  T Verebély  W Rascher 《Orvosi hetilap》1989,130(43):2299-300, 2303-4
Authors investigated the concentration changes of arginine vasopressin (AVP) and of atrial natriuretic peptide (ANP) in plasma. The renal characteristics of water- and sodium metabolism in the first 24 hours of the postoperative period in 11 children operated with acute appendicitis have been studied. Crystalloid infusion was applied in 60 ml/kg/24 h dose, in 5 cases however, 1 g/kg albumin vas also administered during the operation. In children getting crystalloid infusion (group "A") the initial AVP value was 29.9 +/- 8.8 pg/ml, which further increased to 58.2 +/- 15.2 pg/ml (p 0.05) by the 6. postoperative hour and even in the 24. hour it remained above the physiological value (19.9 +/- 5.3 pg/ml). During the observation time significant Na- and water retention developed. The albumin administration (group "B") stopped the further increase of AVP values, the Na-household remained in equilibrium and the water retention developed only in smaller degree. The ANP plasma concentration of both groups was in the normal range and did not change during observation time. Our data show that for the postoperative water retention first of all the increased AVP activity is responsible. The more intensive AVP secretion may be induced by the relative intravascular hypovolemia since by enhancing the plasma volume the further increase of postoperative hormone activity could be prevented.  相似文献   
8.
Baldauf ZB 《Neuroscience letters》2005,383(1-2):109-114
The distribution pattern of SMI-32-immunoreactivity (SMI-32-ir) of neuronal elements was examined in the visual cortical areas of marmoset monkey. Layer IV of the primary visual cortex (V1) and layers III and V of the extrastriate areas showed the most abundant SMI-32-ir. The different areal and laminar distribution of SMI-32-ir allowed the distinction between various extrastriate areas and determined their exact anatomical boundaries in the New World monkey, Callithrix penicillata. It is shown here that the parcellating nature of SMI-32 described earlier in the visual cortical areas of other mammals - including Old World monkeys - is also present in the marmoset. Furthermore, a comparison became possible between the chemoanatomical organization of New World and Old World primates' visual cortical areas.  相似文献   
9.
Effects of chemical mediators of anaphylaxis on ciliary function   总被引:2,自引:0,他引:2  
We assessed the effects of selected chemical mediators of anaphylaxis on CBF in vitro. Ciliated epithelial cells were obtained from the trachea of conscious sheep with a cytology brush and suspended in a perfusion chamber containing KH. Ciliary activity was viewed microscopically and recorded on videotape for subsequent slow-motion analysis of CBF. Prostaglandin E1 (10(-8) M to 10(-6) M), prostaglandin E2 (10(-10) M to 10(-6) M), and leukotriene-C4 (10(-8) M) increased CBF between 7% and 33%. Histamine caused ciliostimulation only at the relatively high concentrations above 10(-5) M (7% increase in CBF), whereas prostaglandin F2 alpha (10(-10) M and 10(-6) M) was without effect. In no preparation was ciliary discoordination observed. These findings indicate that several chemical mediators of anaphylaxis stimulate CBF and that the previously described impairment of mucociliary transport in stable allergic asthma or antigen-induced bronchoconstriction is probably not caused by a primary alteration of ciliary function.  相似文献   
10.
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