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   1248篇
  免费   48篇
  国内免费   13篇
耳鼻咽喉   12篇
儿科学   39篇
妇产科学   18篇
基础医学   108篇
口腔科学   36篇
临床医学   80篇
内科学   386篇
皮肤病学   6篇
神经病学   101篇
特种医学   49篇
外科学   217篇
综合类   5篇
一般理论   6篇
预防医学   53篇
眼科学   24篇
药学   57篇
中国医学   1篇
肿瘤学   111篇
  2023年   9篇
  2022年   8篇
  2021年   23篇
  2020年   16篇
  2019年   24篇
  2018年   22篇
  2017年   14篇
  2016年   19篇
  2015年   23篇
  2014年   42篇
  2013年   64篇
  2012年   97篇
  2011年   115篇
  2010年   61篇
  2009年   63篇
  2008年   103篇
  2007年   118篇
  2006年   112篇
  2005年   100篇
  2004年   84篇
  2003年   64篇
  2002年   57篇
  2001年   10篇
  2000年   1篇
  1999年   6篇
  1998年   8篇
  1997年   7篇
  1996年   7篇
  1995年   7篇
  1994年   2篇
  1993年   6篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1983年   1篇
  1980年   1篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1966年   1篇
  1956年   1篇
排序方式: 共有1309条查询结果,搜索用时 31 毫秒
41.
42.
Carbon nanotubes (CNTs) exhibit unique properties which have led to their applications in the biomedical field as novel delivery systems for diagnosis and therapy purposes. We have previously reported that the degree of functionalization of CNTs is a key factor determining their biological behaviour. The present study broadens the spectrum by investigating the impact of the diameter of CNTs using two series of multi-walled CNTs (MWNTs) with distinct differences in their diameters. Both MWNTs were doubly functionalized by 1,3-dipolar cycloaddition and amidation reactions, allowing the appended functional groups to be further conjugated with radionuclide chelating moieties and antibodies or antibody fragments. All constructs possessed comparable degree of functionalization and were characterized by thermogravimetric analysis, transmission electron microscopy, gel electrophoresis and surface plasmon resonance. The MWNT conjugates were radio-labelled with indium-111, which thereby enabled in vivo single photon emission computed tomography/computed tomography (SPECT/CT) imaging and organ biodistribution study using γ-scintigraphy. The narrow MWNTs (average diameter: 9.2 nm) demonstrated enhanced tissue affinity including non-reticular endothelial tissues compared to the wider MWNTs (average diameter: 39.5 nm). The results indicate that the higher aspect ratio of narrow MWNTs may be beneficial for their future biological applications due to higher tissue accumulation.  相似文献   
43.
44.
Chronic kidney disease(CKD) patients face an unacceptably high morbidity and mortality, mainly from cardiovascular diseases. Diabetes mellitus, arterial hypertension and dyslipidemia are highly prevalent in CKD patients. Established therapeutic protocols for the treatment of diabetes mellitus, arterial hypertension,and dyslipidemia are not as effective in CKD patients as in the general population. The role of non-traditional risk factors(RF) has gained interest in the last decades. These entail ...  相似文献   
45.
Goal-directed movements involve a series of neural computations that compare the sensory representations of goal location and effector position, and transform these into motor commands. Neurons in posterior parietal cortex (PPC) control several effectors (e.g., eye, hand, foot) and encode goal location in a variety of spatial coordinate systems, including those anchored to gaze direction, and to the positions of the head, shoulder, or hand. However, there is little evidence on whether reference frames depend also on the effector and/or type of motor response. We addressed this issue in macaque PPC area V6A, where previous reports using a fixate-to-reach in depth task, from different starting arm positions, indicated that most units use mixed body/hand-centered coordinates. Here, we applied singular value decomposition and gradient analyses to characterize the reference frames in V6A while the animals, instead of arm reaching, performed a nonspatial motor response (hand lift). We found that most neurons used mixed body/hand coordinates, instead of “pure” body-, or hand-centered coordinates. During the task progress the effect of hand position on activity became stronger compared to target location. Activity consistent with body-centered coding was present only in a subset of neurons active early in the task. Applying the same analyses to a population of V6A neurons recorded during the fixate-to-reach task yielded similar results. These findings suggest that V6A neurons use consistent reference frames between spatial and nonspatial motor responses, a functional property that may allow the integration of spatial awareness and movement control.  相似文献   
46.
Dietary pattern may potentially impact on the pathogenesis of asthma and allergies. The Mediterranean Diet (MD) has significant health benefits due to its antioxidant and anti-inflammatory properties. The aim of this systematic review was to investigate the effectiveness of adherence to the MD against asthma and allergies in childhood. Hence, a systematic literature search was conducted on PubMed, ESBCO (Cinahl), Scopus, and the Cochrane Library databases up to 26 January 2022. The total number of articles obtained, after the initial search on the databases was conducted, was 301. Twelve studies were included, after the removal of duplicates and screening for eligibility. Our findings indicated a protective role of the MD against childhood asthma, but they also imply that the MD probably does not affect the development of allergies. Nevertheless, the heterogeneity and limitations of the studies highlight the need for randomized controlled trials that will focus on the pediatric population and hopefully provide more robust evidence.  相似文献   
47.
Next-generation sequencing has revealed novel recurrent mutations in chronic lymphocytic leukemia, particularly in patients with aggressive disease. Here, we explored targeted re-sequencing as a novel strategy to assess the mutation status of genes with prognostic potential. To this end, we utilized HaloPlex targeted enrichment technology and designed a panel including nine genes: ATM, BIRC3, MYD88, NOTCH1, SF3B1 and TP53, which have been linked to the prognosis of chronic lymphocytic leukemia, and KLHL6, POT1 and XPO1, which are less characterized but were found to be recurrently mutated in various sequencing studies. A total of 188 chronic lymphocytic leukemia patients with poor prognostic features (unmutated IGHV, n=137; IGHV3-21 subset #2, n=51) were sequenced on the HiSeq 2000 and data were analyzed using well-established bioinformatics tools. Using a conservative cutoff of 10% for the mutant allele, we found that 114/180 (63%) patients carried at least one mutation, with mutations in ATM, BIRC3, NOTCH1, SF3B1 and TP53 accounting for 149/177 (84%) of all mutations. We selected 155 mutations for Sanger validation (variant allele frequency, 10–99%) and 93% (144/155) of mutations were confirmed; notably, all 11 discordant variants had a variant allele frequency between 11–27%, hence at the detection limit of conventional Sanger sequencing. Technical precision was assessed by repeating the entire HaloPlex procedure for 63 patients; concordance was found for 77/82 (94%) mutations. In summary, this study demonstrates that targeted next-generation sequencing is an accurate and reproducible technique potentially suitable for routine screening, eventually as a stand-alone test without the need for confirmation by Sanger sequencing.  相似文献   
48.
Understanding the mechanisms responsible for carbon nanotube (CNT) internalisation into live cells is considered critical both from a fundamental point of view and for further engineering of CNT-based delivery systems to intracellular targets. While several studies are focused on the development of such CNT-based delivery systems, attempts to systematically elucidate the cellular uptake mechanisms of CNTs are still rather limited. The aim of the present study is to evaluate the cellular internalisation of chemically functionalised multi-walled carbon nanotubes (f-MWCNTs) in the presence of different well-known cellular uptake inhibitors. Our data reveal how f-MWCNTs are able to translocate across cell membranes of both phagocytic and non-phagocytic cell lines. We have evidenced that at least 30-50% of f-MWCNTs are taken up by cells through an energy-independent mechanism. This characteristic makes nanotubes loaded with therapeutic or diagnostic cargos extremely interesting as the release of active molecules directly into the cytoplasm increase their biological activity and therapeutic efficacy.  相似文献   
49.
OBJECTIVE: This study aimed to show that during hypokinesia (HK), phosphate (P(i)) imbalance increases more with higher than lower physical activity and that P(i) absorption reduces more with higher than lower P(i) imbalance in subjects with higher than lower muscular activity. METHODS: Studies were conducted on 30 healthy male subjects during 364 days of HK. They were equally divided in three groups: unrestricted active control subjects (UACS), continuously hypokinetic subjects (CHKS) and periodically hypokinetic subjects (PHKS). CHKS were kept under average walking distances of 0.5+/-0.2 km day(-1) PHKS were kept under average walking distances of 0.5+/-0.1 and running average distances of 8.7+/-1.2 km day(-l) for 5 days and 2 days per week, respectively. UACS were placed under average running distances of 8.7+/-1.2 km day(-l). RESULTS: P(i) imbalance, serum, urine and fecal P(i) levels, and urine and serum calcium (Ca(2+)) levels increased significantly (p<0.05) and P(i) absorption, and serum intact parathyroid hormone (iPTH) and 1,25-dehydroxyvitamin D (1,25 (OH)(2) D(3)) levels decreased significantly (p<0.05) in CHKS and PHKS compared with their pre-HK values and their respective active control (UACS). However, the P(i) imbalance, serum, urine and fecal P(i) levels, and serum and urine Ca(2+) levels increased more significantly (p<0.05), and P(i) absorption and serum iPTH and 1,25 (OH)(2) D(3) levels decreased more significantly in PHKS than in CHKS. CONCLUSIONS: Higher P(i) imbalance with higher than lower physical activity shows that the risk of higher P(i) imbalance is inversely related to the intensity of physical activity. Lower P(i) absorption with higher than lower P(i) imbalance shows that the risk of lower P(i) absorption is inversely related to magnitude of P(i) imbalance. In conclusion P(i) imbalance increases more with higher than lower physical activity and that P(i) absorption decreases more with higher than lower P(i) imbalance indicating that during HK the use of P(i) decreases more with higher than lower physical activity.  相似文献   
50.
The Trellis Peripheral Infusion System is an over-the-wire 0.035 guidewire compatible device, designed to isolate a region of the peripheral vasculature to allow for lytic drug infusion and dispersion. We used it successfully through a percutaneous approach in two cases of acute thrombosis of a native lower limb artery. The total amount of rt-PA used was 12 and 9 mg, respectively and was delivered through bolus injections obviating the need for a supplementary continuous infusion of the agent. The time for dissolution of thrombus was 45 and 35 minutes, respectively. No complications were observed.  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