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   160584篇
  免费   33300篇
  国内免费   2411篇
耳鼻咽喉   5314篇
儿科学   5647篇
妇产科学   2572篇
基础医学   4618篇
口腔科学   1782篇
临床医学   27656篇
内科学   49376篇
皮肤病学   7613篇
神经病学   15845篇
特种医学   6803篇
外科学   42804篇
综合类   443篇
现状与发展   72篇
一般理论   13篇
预防医学   7893篇
眼科学   3683篇
药学   1630篇
中国医学   14篇
肿瘤学   12517篇
  2024年   515篇
  2023年   4811篇
  2022年   1187篇
  2021年   3201篇
  2020年   6100篇
  2019年   2318篇
  2018年   7533篇
  2017年   7440篇
  2016年   8519篇
  2015年   8587篇
  2014年   15731篇
  2013年   16112篇
  2012年   6082篇
  2011年   6183篇
  2010年   10683篇
  2009年   14553篇
  2008年   6512篇
  2007年   4800篇
  2006年   7236篇
  2005年   4594篇
  2004年   3765篇
  2003年   2729篇
  2002年   2818篇
  2001年   3885篇
  2000年   3082篇
  1999年   3294篇
  1998年   3800篇
  1997年   3579篇
  1996年   3480篇
  1995年   3322篇
  1994年   2037篇
  1993年   1662篇
  1992年   1446篇
  1991年   1480篇
  1990年   1119篇
  1989年   1231篇
  1988年   1089篇
  1987年   899篇
  1986年   950篇
  1985年   771篇
  1984年   631篇
  1983年   601篇
  1982年   619篇
  1981年   503篇
  1980年   467篇
  1979年   369篇
  1978年   396篇
  1977年   473篇
  1975年   333篇
  1972年   321篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Background Hydatid disease is the most severe helminthic zoonosis, with an important public health problem especially in rural areas in Turkey. The aim of this study was to review the problems and advantages encountered in surgical treatment of 43 patients who were ventilated with one-lung ventilation during last four years. Methods Patients, operated with one-lung ventilation, constitute the study group. Data related to symptoms, radiographic findings, performed surgical procedures, perioperative and postoperative morbidity, hospitalization time, and cyst recurrence were collected from each individual's records. Results Cystotomy and capitonnage were performed in all cases. Perioperative complications were seen in 5 patients. Four of these 5 patients had double-lumen endotracheal tube malpositioning. In one patient hypoxemia developed. The most common postoperative complication was atelectasis. One patient had recurrent cysts. There was no perioperative or postoperative death. Conclusions We prefer cystotomy and capitonnage because it is a fast and effective technique with limited postoperative complications. One-lung ventilation prevents the exposure of lower lung areas from massive aspiration, which may cause acute obstruction of airways, and contamination by cyst contents from the operative part of the lung that causes recurrent disease. One-lung ventilation in pulmonary hydatid cyst surgery may be preferred owing to lower mortality and morbidity rates.  相似文献   
112.
SONI NANDA  MD    VINEET RELHAN  MD    CHANDER GROVER  MD  DNB  MNAMS    B.S.N. REDDY  MD  MNAMS 《Dermatologic surgery》2006,32(3):387-392
BACKGROUND: Suction blister epidermal grafting is an established technique for the treatment of resistant and stable vitiligo especially over small and cosmetically important areas like the face. However, certain areas, such as lips and eyelids, require special considerations because of their anatomic peculiarities. PATIENTS AND METHODS: The current study was carried out on six patients of stable eyelid vitiligo, not responding to medical treatment. Suction blister was obtained from the thigh using the suction apparatus and the roof was grafted on to the dermabraded eyelid. Certain precautions were taken during the procedure, which will be highlighted in the current study. RESULTS: Response was excellent in all the patients in 3 to 6 months, with no complications. CONCLUSIONS: If carried out properly, suction blister technique is the procedure of choice for cosmetically important sites like eyelids.  相似文献   
113.
Genetically modified keratinocytes and fibroblasts are suitable for delivery of therapeutic genes capable of modifying the wound healing process. However, efficient gene delivery is a prerequisite for successful gene therapy of wounds. Whereas adenoviral vectors (Ads) exhibit superior levels of in vivo gene transfer, their transductional efficiency to cells resident within wounds may nonetheless be suboptimal, due to deficiency of the primary adenovirus receptor, coxsackie-adenovirus receptor (CAR). We explored CAR-independent transduction to fibroblasts and keratinocytes using a panel of CAR-independent fiber-modified Ads to determine enhancement of infectivity. These fiber-modified adenoviral vectors included Ad 3 knob (Ad5/3), canine Ad serotype 2 knob (Ad5CAV-2), RGD (Ad5.RGD), polylysine (Ad5.pK7), or both RGD and polylysine (Ad5.RGD.pK7). To evaluate whether transduction efficiencies of the fiber-modified adenoviral vectors correlated with the expression of their putative receptors on keratinocytes and fibroblasts, we analyzed the mRNA levels of CAR, alpha upsilon integrin, syndecan-1, and glypican-1 using quantitative polymerase chain reaction. Analysis of luciferase and green fluorescent protein transgene expression showed superior transduction efficiency of Ad5.pK7 in keratinocytes and Ad5.RGD.pK7 in fibroblasts. mRNA expression of alpha upsilon integrin, syndecan-1 and glypican-1 was significantly higher in primary fibroblasts than CAR. In keratinocytes, syndecan-1 expression was significantly higher than all the other receptors tested. Significant infectivity enhancement was achieved in keratinocytes and fibroblasts using fiber-modified adenoviral vectors. These strategies to enhance infectivity may help to achieve higher clinical efficacy of wound gene therapy.  相似文献   
114.
115.
116.
117.
Hydration and Cognitive Function in Children   总被引:3,自引:0,他引:3  
Adequate fluid intake is critical for survival. While adults are at liberty to drink fluids as wanted, children and infants are dependent upon caregivers for food and fluid. Children are at greater risk for dehydration than adults due to their higher surface-to-mass ratio. Additionally, children have different thirst sensitivities and body cooling mechanisms than adults. Children differ from adults in total body water content, and boys and girls differ in body water content with maturation. Research in young adults shows that mild dehydration corresponding to only 1% to 2% of body weight loss can lead to significant impairment in cognitive function. Dehydration in infants is associated with confusion, irritability, and lethargy; in children, it may produce decrements in cognitive performance.  相似文献   
118.
BACKGROUND AND PURPOSE: Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. METHODS: To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH < or =2 cm was estimated, using the number of dotHSs and risk factors for stroke. RESULTS: The number of dotHSs associated with the diameter < or =2 cm was 9.2 +/- 11.5, significantly larger than that with the diameter > or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). CONCLUSION: Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH.  相似文献   
119.
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   
120.
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