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   6909篇
  免费   343篇
  国内免费   52篇
耳鼻咽喉   78篇
儿科学   111篇
妇产科学   105篇
基础医学   910篇
口腔科学   539篇
临床医学   483篇
内科学   1726篇
皮肤病学   114篇
神经病学   894篇
特种医学   182篇
外科学   934篇
综合类   29篇
一般理论   4篇
预防医学   323篇
眼科学   157篇
药学   376篇
中国医学   28篇
肿瘤学   311篇
  2024年   5篇
  2023年   79篇
  2022年   177篇
  2021年   295篇
  2020年   186篇
  2019年   236篇
  2018年   272篇
  2017年   154篇
  2016年   194篇
  2015年   250篇
  2014年   308篇
  2013年   348篇
  2012年   546篇
  2011年   624篇
  2010年   312篇
  2009年   268篇
  2008年   481篇
  2007年   438篇
  2006年   414篇
  2005年   364篇
  2004年   337篇
  2003年   284篇
  2002年   254篇
  2001年   61篇
  2000年   43篇
  1999年   36篇
  1998年   46篇
  1997年   26篇
  1996年   33篇
  1995年   24篇
  1994年   19篇
  1993年   19篇
  1992年   21篇
  1991年   12篇
  1990年   15篇
  1989年   9篇
  1988年   5篇
  1987年   8篇
  1986年   11篇
  1984年   7篇
  1983年   8篇
  1982年   11篇
  1981年   6篇
  1980年   7篇
  1979年   4篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1972年   5篇
  1966年   3篇
排序方式: 共有7304条查询结果,搜索用时 15 毫秒
81.
Sport Sciences for Health - The generalized joint hypermobility (GJH) syndrome is a condition characterized by a connective tissue disorder that may negatively affect the muscle function and muscle...  相似文献   
82.
La radiologia medica - This study aims to analyze safety and effectiveness of PHIL® (Microvention, CA-USA) in peripheral endovascular embolization procedures, both in elective and emergent...  相似文献   
83.
84.
Alpha-2a-interferon (IFN) has demonstrable activity in advance and refractory multiple myeloma (MM), because of the in vitro synergism between IFNs and cytotoxic agents we report the preliminary results of a therapeutic trial of 50 patients with MM. Twenty-eight patients were randomized to receive melphalan plus prednisone (MP) and 22 were randomized to receive IFN plus MP (IFN-MP). Criteria for response, progression and relapse were those of the Southwestern Oncology Group. 95% of the patients receiving IFN-MP responded to therapy as opposed to 68% of the patients receiving MP (P less than 0.05). Response was independent of M-component immunoglobulin class but in stage III it was higher in the IFN-MP group than in the MP group (P less than 0.05). The combination IFN-MP was well tolerated without unusual or unexpected toxic effects. The response duration time was longer in the IFN-MP group than in the MP group (P less than 0.025). The median survival was 80 weeks in the MP group and in the IFN-MP group the 93% of patients were still alive after 90 weeks (P less than 0.025). Our results show that the use of the IFN as an adjuvant to MP improves the percentage of responders, the response duration time and the median survival of untreated patients with MM.  相似文献   
85.
Non-atopic asthma is the predominant phenotype in non-affluent parts of Latin America. We recently reported that infestation with Ascaris lumbricoides increased the risk of non-atopic asthma in less affluent areas of Brazil but the mechanism is unclear. The present study was conducted to determine whether helminth infestation is associated with heightened bronchial responsiveness (BHR), a common finding in asthma. A random sample of 50 asthmatic and 50 non-asthmatic controls (mean age 10.1 years) were selected from a larger cohort (n = 1,011) without knowledge of their helminth infestation status. Three stool samples were collected from each child on different days and each sample was analyzed by the Kato-Katz method for quantitative determination of helminth eggs. Bronchial provocation tests were performed with inhaled 4.5% hypertonic saline using the ISAAC Phase II standardized protocol. There was no difference between the prevalence of positive BHR in the asthmatics (20.4%) compared with the controls (14.6%) (P = 1.0). Helminth infestation was detected in 24.0% of children, with A. lumbricoides being the most common. Children with high load infestation (>or=100 eggs/g) were five times more likely to have BHR than children with low load or no infestation. Despite the small sample size the results of the present study suggest that the link between high load helminth infestation and non-atopic asthma may be mediated via heightened bronchial responsiveness, possibly due to an inflammatory response to the pulmonary phase of the helminth life cycle.  相似文献   
86.
OBJECTIVE: Therapeutic splenectomy in myelofibrosis with myeloid metaplasia (MMM) may result in extreme thrombocytosis and leukocytosis and accelerated hepatomegaly. We previously described initial palliative benefit from 2-chlorodeoxyadenosine (2-CdA) in such instances. The purpose of this study is to provide long-term follow-up on the durability of response in the initial cohort and in additional subsequent cases. METHODS: We retrospectively identified patients with histologically confirmed MMM who had palliative therapy with 2-CdA. Clinical characteristics and information on subsequent clinical course were abstracted at the time of diagnosis of MMM and at initiation of 2-CdA therapy until death. RESULTS: To date, we have used 2-CdA as palliative therapy in 14 patients with MMM. After a median of four cycles of therapy, responses for hepatomegaly occurred in 56% of patients, thrombocytosis 50%, leukocytosis 55%, and anemia 40%. Cytopenias were frequent but usually transient and without clinical consequence. Responses occurred usually by the second cycle; median duration of response was 6 months (range, 2-19) after completion of 2-CdA therapy. CONCLUSION: This study confirmed relevant and frequently durable palliation of symptoms in about half the patients. 2-CdA is a reasonable palliative option in postsplenectomy patients with MMM who have problematic myeloproliferation.  相似文献   
87.
The cutaneous postischemic hyperemia test, by means of laser Doppler flowmetry, was carried out on 71 normal, healthy lower extremities and 138 lower limbs suffering from peripheral occlusive arterial disease. The test, a new technique for evaluating the hemodynamics of limbs, permitted a clear distinction between normal, healthy subjects and patients suffering from arterial disorders. It was also seen that the degree of deterioration in the quantitative parameters was quite obviously related to the seriousness of the clinical picture. A comparison of the more severely and less severely affected limbs of each patient and the values taken bilaterally gave a correspondence of 98.6%. A therapeutic cycle consisting of the intraarterial administration of naftidrofuryl in 20 limbs achieved a statistically significant improvement in two parameters (tL and tR). Four limbs were treated with percutaneous transluminal angioplasty. After treatment the values obtained with the test were found to be absolutely normal. It is therefore suggested that this test be widely adopted in vascular diagnostic laboratories.  相似文献   
88.
The technique of "T" stenting, which incorporates wiring both the branches of a bifurcation lesion, dilating a balloon in the main branch during stent deployment in the side branch followed by deployment of stent in the main branch, provides excellent immediate results in terms of technical and procedural success. However, further innovations are mandated to optimize the long-term outcome, which with a restenosis rate of 63%, can be described as not encouraging.  相似文献   
89.
90.
Inhibitory interneurons expressing parvalbumin (PV) are central to cortical network dynamics, generation of γ oscillations, and cognition. Dysfunction of PV interneurons disrupts cortical information processing and cognitive behavior. Brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (trkB) signaling regulates the maturation of cortical PV interneurons but is also implicated in their adult multidimensional functions. Using a novel viral strategy for cell-type-specific and spatially restricted expression of a dominant-negative trkB (trkB.DN), we show that BDNF/trkB signaling is essential to the integrity and maintenance of prefrontal PV interneurons in adult male and female mice. Reduced BDNF/trkB signaling in PV interneurons in the medial prefrontal cortex (mPFC) resulted in deficient PV inhibition and increased baseline local field potential (LFP) activity in a broad frequency band. The altered network activity was particularly pronounced during increased activation of the prefrontal network and was associated with changed dynamics of local excitatory neurons, as well as decreased modulation of the LFP, abnormalities that appeared to generalize across stimuli and brain states. In addition, our findings link reduced BDNF/trkB signaling in prefrontal PV interneurons to increased aggression. Together our investigations demonstrate that BDNF/trkB signaling in PV interneurons in the adult mPFC is essential to local network dynamics and cognitive behavior. Our data provide direct support for the suggested association between decreased trkB signaling, deficient PV inhibition, and altered prefrontal circuitry.SIGNIFICANCE STATEMENT Brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (trkB) signaling promotes the maturation of inhibitory parvalbumin (PV) interneurons, neurons central to local cortical dynamics, γ rhythms, and cognition. Here, we used a novel viral approach for reduced BDNF/trkB signaling in PV interneurons in the medial prefrontal cortex (mPFC) to establish the role of BDNF/trkB signaling in adult prefrontal network activities. Reduced BDNF/trkB signaling caused pronounced morphologic alterations, reduced PV inhibition, and deficient prefrontal network dynamics. The altered network activity appeared to manifest across stimuli and brain states and was associated with aberrant local field potential (LFP) activities and increased aggression. The results demonstrate that adult BDNF/trkB signaling is essential to PV inhibition and prefrontal circuit function and directly links BDNF/trkB signaling to network integrity in the adult brain.  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