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   2163篇
  免费   129篇
  国内免费   34篇
耳鼻咽喉   6篇
儿科学   80篇
妇产科学   58篇
基础医学   259篇
口腔科学   61篇
临床医学   274篇
内科学   387篇
皮肤病学   19篇
神经病学   164篇
特种医学   319篇
外科学   219篇
综合类   53篇
预防医学   156篇
眼科学   16篇
药学   128篇
中国医学   1篇
肿瘤学   126篇
  2023年   15篇
  2022年   12篇
  2021年   20篇
  2020年   20篇
  2019年   32篇
  2018年   41篇
  2017年   20篇
  2016年   28篇
  2015年   35篇
  2014年   53篇
  2013年   63篇
  2012年   82篇
  2011年   93篇
  2010年   83篇
  2009年   55篇
  2008年   73篇
  2007年   107篇
  2006年   91篇
  2005年   74篇
  2004年   71篇
  2003年   68篇
  2002年   52篇
  2001年   56篇
  2000年   52篇
  1999年   61篇
  1998年   72篇
  1997年   86篇
  1996年   88篇
  1995年   56篇
  1994年   47篇
  1993年   47篇
  1992年   31篇
  1991年   31篇
  1990年   45篇
  1989年   57篇
  1988年   57篇
  1987年   46篇
  1986年   45篇
  1985年   41篇
  1984年   17篇
  1983年   27篇
  1982年   15篇
  1981年   15篇
  1980年   14篇
  1979年   10篇
  1978年   10篇
  1977年   22篇
  1976年   14篇
  1975年   14篇
  1968年   8篇
排序方式: 共有2326条查询结果,搜索用时 0 毫秒
71.
72.
Australia has a large migrant population with variable fluency in English. Interpreting services help ensure that healthcare services are delivered appropriately to these populations. However, the use of professional interpreters in hospitals is expensive. There are also issues with service availability and convenience. Mobile devices containing software with translating abilities have promising potential to improve communication between patients and hospital staff as an adjunct to professional interpreters. It is highly convenient and inexpensive. There are concerns about the accuracy of the interpretation done with such software and more research needs to be carried out to support or allay these concerns. For now, clinically important and medicolegal related interpretation should be undertaken by professional interpreters whereas less crucial tasks may be performed with the help of interpreting software on mobile devices.  相似文献   
73.
74.
Grief is a family affair, yet it is commonly viewed as an individual phenomenon. As an international, interdisciplinary team, we explore grief within a family context across theoretical, research, practice, and educational domains. Families are complex and working with this complexity is challenging but necessary for a holistic view of grief. We therefore encourage an increased focus on theorizing, researching, practicing, and educating using innovative approaches to address the complexities of grief within the context of families. Learnings from within each domain will affirm and enhance the development of family-level thinking and approaches.  相似文献   
75.
Thrombin causes subsecond changes in protein phosphorylation of platelets   总被引:1,自引:0,他引:1  
Carty  DJ; Spielberg  F; Gear  AR 《Blood》1986,67(6):1738-1743
We have developed a general quenched-flow approach to study platelet function as early as 0.3 seconds after stimulation. Phosphorylation of 20- and 40-kd proteins has been analyzed during the first five seconds of platelet response to thrombin from 0.1 to 5.0 U/mL and compared with the progress of aggregation and serotonin secretion. The onset time for aggregation and phosphorylation of both proteins was less than one second, although with lowest (less than 0.5 U/mL) thrombin levels, a lag of up to 0.6 seconds occurred before 40K phosphorylation increased. The thrombin sensitivity of aggregation and 20K phosphorylation was approximately twice that of 40K phosphorylation, with Ka values of 0.51 and 0.53 v 1.10 U/mL, respectively. External calcium was necessary for maximal 20K phosphorylation, since EDTA inhibited this by 30%. The 40K phosphorylation was not affected by EDTA. Platelet activation by thrombin thus induced biochemical changes well before one second. The quenched-flow approach may help to reveal relationships between phospholipase activation, calcium fluxes, and protein phosphorylation during these early periods of platelet function.  相似文献   
76.
Smythe  JS; Spring  FA; Gardner  B; Parsons  SF; Judson  PA; Anstee  DJ 《Blood》1995,85(10):2929-2936
This report describes the production and characterization of 13 rodent monoclonal antibodies to the human erythrocyte anion transport protein AE1 (syn. band 3). Eleven antibodies (4 murine and 7 rat) recognize epitopes dependent on the integrity of the third extracellular loop of the protein. Two antibodies (1 murine and 1 rat) recognize epitopes on the N-terminal cytoplasmic domain. Quantitative binding studies using radioiodinated IgG and Fab fragments of antibodies to extracellular epitopes on AE1 ranged from 77,000 to 313,000 (IgG) and from 241,000 to 772,000 (Fab) molecules bound at saturation. The results indicate that the epitopes recognized by different antibodies vary in their accessibility and suggest that there is heterogeneity in the organization of individual AE1 molecules in the red blood cell membrane. Quantitative binding studies on South East Asian ovalocytes using several antibodies to AE1 and an anti-Wrb show a marked reduction in the number of antibody molecules bound at saturation. These results are consistent with the existence of highly cooperative interactions between transmembrane domains of AE1 in normal erythrocytes and the disruption of these interactions in the variant AE1 found in South East Asian ovalocytes.  相似文献   
77.
Loskutoff  DJ; Mussoni  L 《Blood》1983,62(1):62-68
Serum-free conditioned medium (CM) from cultured bovine aortic endothelial cells (BAEs) was fractionated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and analyzed for plasminogen activator (PA) activity by fibrin autography. Distinct size forms of PA with molecular weights (mol wt) of 100,000, 74,000, and 52,000 were readily identified by this approach. When fibrinogen and thrombin were added to CM containing these forms, approximately 55% of the total activity was found to associate with the resultant fibrin clot. The other 45% remained free in the supernatant. This relationship did not change at higher fibrin concentrations. Subsequent analysis revealed that only the larger PA forms (mol wt 74,000-100,000) were recovered in the clot. The 52,000 form did not bind to the polymerizing fibrin under these conditions. The fibrin-binding forms also bound to immobilized concanavalin-A and could be separated from those forms that did not interact with fibrin by concanavalin-A affinity chromatography. The PA activity of the separated forms was then compared by assessing their ability to cleave 125I-plasminogen. Although cleavage by the 52,000 mol wt form was apparent, little if any cleavage was initiated by the mixture containing the 74,000-100,000 forms. The addition of fibrin to this sample resulted in the generation of a potent PA activity. These results indicate that cultured BAEs produce multiple forms of PA that differ both in size and in behavior toward fibrin and concanavalin-A. These forms include molecules that functionally and immunochemically resemble human urokinase, and others that resemble human tissue-type PA.  相似文献   
78.
Thein  SL; Hesketh  C; Brown  JM; Anstey  AV; Weatherall  DJ 《Blood》1989,73(4):924-930
Two families, one of Anglo-Saxon-Dutch descent, and the other, West Indian black, have an atypical beta thalassemia characterized by an unusually high level of Hb A2 in the heterozygous state. Restriction endonuclease mapping showed a deletion of about 1.35 kilobase (kb) in the 5' region of the beta globin gene. Direct sequencing of a specific region of genomic DNA amplified by a new modification of the polymerase chain reaction defined the deletion to be 1,393 base pairs (bp) and to be the same in both families. The deletion extends from 485 bp 5' to the mRNA CAP site to the middle of the second intervening sequence. This deletion, together with three others previously described that remove the 5' end of the beta gene but leave the delta gene intact, are all associated with unusually high levels of Hb A2 in the heterozygous state.  相似文献   
79.
OBJECTIVES: We sought to assess the impact of contrast injection and harmonic imaging, on the measure by echocardiography of left ventricular (LV) remodeling. BACKGROUND: Left ventricular remodeling is a precursor of LV dysfunction, but the impact of contrast injection and harmonic imaging on the accuracy or reproducibility of echocardiography is unclear. METHODS: We prospectively collected LV images by using simultaneous methods. Then, LV volumes were measured off-line, in blinded manner and in random order. The accuracy of echocardiography was determined in comparison to electron beam computed tomography (EBCT) in 26 patients. The reproducibility of echocardiography was assessed by three blinded observers with different training levels in 32 patients. RESULTS: End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF), as measured by EBCT (195 +/- 55, 58 +/- 24 and 137 +/- 35 ml and 71 +/- 5%, respectively) and echocardiography with harmonic imaging and contrast injection (194 +/- 51, 55 +/- 20 and 140 +/- 35 ml and 72 +/- 4%, respectively), showed no differences (all p > 0.15) and excellent correlations (all r > 0.87). In contrast, echocardiography using harmonic imaging without contrast injection underestimated the EBCT results (all p < 0.01). Reproducibility was superior with rather than without contrast injection for intraobserver and interobserver variabilities (all p < 0.001). Values measured by different observers were different without contrast injection, but were similar with contrast injection (all p > 0.18). Consequently, intrinsic patient differences represented a larger and almost exclusive proportion of global variability with contrast injection for EDV (94 vs. 79%), ESV (93 vs. 82%), SV (87 vs. 53%) and EF (84 vs. 41%), as compared with harmonic imaging without contrast injection (all p < 0.005). CONCLUSIONS: For assessment of LV remodeling, echocardiography with harmonic imaging and contrast injection improved the accuracy and reproducibility, as compared with imaging without contrast injection. With contrast injection, variability was almost exclusively due to intrinsic patient differences. Therefore, when evaluation of LV remodeling is deemed important, assessment after contrast injection should be the preferred echocardiographic approach.  相似文献   
80.
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