全文获取类型
收费全文 | 3879篇 |
免费 | 175篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 63篇 |
妇产科学 | 42篇 |
基础医学 | 535篇 |
口腔科学 | 71篇 |
临床医学 | 248篇 |
内科学 | 1220篇 |
皮肤病学 | 56篇 |
神经病学 | 218篇 |
特种医学 | 154篇 |
外科学 | 556篇 |
综合类 | 10篇 |
预防医学 | 214篇 |
眼科学 | 38篇 |
药学 | 218篇 |
中国医学 | 2篇 |
肿瘤学 | 400篇 |
出版年
2023年 | 21篇 |
2022年 | 35篇 |
2021年 | 61篇 |
2020年 | 35篇 |
2019年 | 50篇 |
2018年 | 73篇 |
2017年 | 46篇 |
2016年 | 45篇 |
2015年 | 56篇 |
2014年 | 92篇 |
2013年 | 110篇 |
2012年 | 189篇 |
2011年 | 193篇 |
2010年 | 122篇 |
2009年 | 95篇 |
2008年 | 187篇 |
2007年 | 233篇 |
2006年 | 245篇 |
2005年 | 219篇 |
2004年 | 208篇 |
2003年 | 188篇 |
2002年 | 200篇 |
2001年 | 83篇 |
2000年 | 102篇 |
1999年 | 109篇 |
1998年 | 51篇 |
1997年 | 65篇 |
1996年 | 50篇 |
1995年 | 35篇 |
1994年 | 32篇 |
1993年 | 39篇 |
1992年 | 74篇 |
1991年 | 80篇 |
1990年 | 72篇 |
1989年 | 67篇 |
1988年 | 73篇 |
1987年 | 56篇 |
1986年 | 52篇 |
1985年 | 41篇 |
1984年 | 30篇 |
1983年 | 42篇 |
1982年 | 19篇 |
1980年 | 17篇 |
1979年 | 26篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1971年 | 12篇 |
1970年 | 12篇 |
1965年 | 11篇 |
排序方式: 共有4075条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Yoshiyuki Kurata Machiko Oshida Hironori Take Takayasu Furubayashi Hirohisa Nakao Yoshiaki Tomiyama Yoshio Kanayama Nobuo Nagao Yasuto Okubo Takeshi Yonezawa and Seiichiro Tarui 《Vox sanguinis》1989,57(3):199-204
A new method was studied for eliminating HLA class I antigens from the surface of platelets without damaging the cells. Platelets were exposed to an acid solution (pH 3.0) to eliminate the antigenicity of HLA class I antigens. The reduction in antigenicities of HLA class I common antigen and individual HLA class I antigens by acid treatment was marked. Patients' sera which contained multispecific HLA antibodies reacted with PBS-treated platelets, but not with acid-treated platelets. No changes were observed in the antigenicities of glycoprotein Ib or glycoprotein IIb/IIIa. The viability of acid-treated platelets was 83%. Ultrastructural investigations revealed no significant difference between the PBS-treated platelets and acid-treated platelets. The platelet function studies showed that the aggregation of acid-treated platelets induced by various agonists was only slightly reduced compared with PBS-treated platelets. We propose that acid-treated platelets are promising for clinical use in patients refractory to platelet transfusions and may be superior to chloroquine-treated platelets for analysis of the specificity of antiplatelet antibodies. 相似文献
75.
Rodriguez CJ Sacco RL Sciacca RR Boden-Albala B Homma S Di Tullio MR 《Journal of the American College of Cardiology》2002,39(9):1482-1488
OBJECTIVES: The goal of this study was to determine whether the risk of ischemic stroke associated with increased left ventricular mass (LVM) is modified by physical activity (PA). BACKGROUND: Increased LVM is associated with an increased risk for stroke. Physical activity can decrease the risk of stroke and may have variable effects on LVM. METHODS: We used a case-control study design in a multiethnic population in northern Manhattan, New York, to study 394 case subjects who had a first ischemic stroke and 413 stroke-free control subjects. All subjects were interviewed and two-dimensional echocardiograms obtained to determine LVM. RESULTS: A sharp increase in risk of ischemic stroke was seen in the highest quartile of LVM (odds ratio [OR]: 6.14 [95% confidence interval [CI]: 3.04 to 12.38]). Thus, increased LVM was defined by the highest quartile of LVM. In multivariate analysis, the effect of increased LVM on the risk of stroke was significantly decreased by the presence of any level of PA versus no PA (OR: 1.59 [95% CI: 0.99 to 2.57] p < 0.07 vs. 3.53 [95% CI: 1.94 to 6.42] p < 0.0001). Although PA decreased the risk of stroke in all patients, the effect was stronger in subjects with increased LVM than among those without increased LVM (p = 0.033). CONCLUSIONS: Increased LVM is associated with an increased risk of stroke, especially among sedentary patients. Physical activity decreases the risk of stroke among patients with increased LVM to a level comparable to that of patients without increased LVM. Recommending PA may be a nonpharmacologic tool to reduce the stroke risk, especially among patients with increased LVM. 相似文献
76.
Shugo Mizuno Takashi Yano Shuji Isaji Shunichi Nakagawa Hajime Yokoi Yoshifumi Kawarada 《Journal of hepato-biliary-pancreatic sciences》1997,4(4):474-479
A 70-year-old woman with gastric cancer was referred to our hospital for further evaluation of a cystic mass in the head of the pancreas. Endoscopic ultrasonography (EUS) showed a mural nodule in the cystic mass. Endoscopic retrograde cholangio pancreatography (ERCP) revealed a cystic lesion with a filling defect caused by obstruction with mucus. Magnetic resonance cholangiopancreatography (MRCP) allowed visualization of the entire configuration of the cystic lesion despite the presence of mucus. Pancreatic juice was positive for K-ras point mutation. Pancreatoduodenectomy was performed, with a diagnosis of intraductal papillary adenoma or adenocarcinoma with gastric cancer. Pancreatography of the resected specimen showed a cystic lesion in the uncinate process, consistent with the MRCP findings. Histological examination revealed an intraductal papillary adenoma. MRCP is very useful for demonstrating the total configuration of cystic lesions and is not impeded by impacted mucin. Nevertheless, because of its lower spatial resolution, this noninvasive modality is of limited value in detecting mural nodules. At present, therefore, surgical indications for cystic lesion of the pancreas should be determined by comprehensively analyzing: size and sequential changes in size of the cyst; presence of mural nodules, cytologic examination for presence of malignant cells, and/or K-ras point mutation in pure pancreatic juice. 相似文献
77.
Yasu T Greener Y Jablonski E Killam AL Fukuda S Suematsu M Tojo SJ Schmid-Schönbein GW 《International journal of cardiology》2005,98(2):245-252
PURPOSE: To characterize the flow dynamics of albumin ultrasound contrast microspheres containing perfluoropropane (PFP) in normal and inflamed microvasculature. MATERIALS AND METHODS: Mesenteric microvessels of rats were examined after an intravenous injection of fluorocein-labeled erythrocytes or PFP microspheres by fluorescence intravital microscopy with and without local application of 10(-8) M platelet activating factor (PAF) as an experimental form of inflammation. RESULTS: All the microspheres passed freely through arterioles and capillaries. Mean velocities of the microspheres in each vessel were closely correlated with those of erythrocytes. Only a minor fraction of the microspheres was retained in the venules (> or =0.1 s stoppage) by attachment to endothelial cells. The frequency of microsphere retention in venules was significantly enhanced by PAF (2.6+/-2.1%, P<0.01 vs. control), especially in regions with leukocyte adhesion. Treatment with a monoclonal antibody to intercellular adhesion molecule-1, P-selectin or the common leukocyte antigen inhibited PAF-induced microsphere retention in venules (P<0.05). In the inflamed microcirculation, a small subgroup of microspheres becomes attached to venular endothelial cells in regions with leukocyte adhesion via interaction among microspheres, activated leukocytes and endothelial cells via adhesion molecules. CONCLUSION: In inflamed microcirculation, a small subgroup of microspheres becomes attached to venular endothelial cells in regions with leukocyte adhesion via interaction among microspheres, activated leukocytes and endothelial cells via adhesion molecules. These results suggest that ultrasonography with microspheres has the potential to evaluate inflammatory site distribution as well as tissue perfusion. 相似文献
78.
Kojima S Sakamoto T Ishihara M Kimura K Miyazaki S Yamagishi M Tei C Hiraoka H Sonoda M Tsuchihashi K Shimoyama N Honda T Ogata Y Matsui K Ogawa H;Japanese Acute Coronary Syndrome Study 《The American journal of cardiology》2005,96(4):489-495
Serum uric acid (UA) levels reflect circulating xanthine oxidase activity and oxidative stress production. Hyperuricemia has been identified in patients who have congestive heart failure and is a marker of poor prognosis in such patients. We investigated the relation between serum UA levels and Killip's classification suggestive of the severity of heart failure and whether hyperuricemia influences mortality of patients who have acute myocardial infarction (AMI). Using the Japanese Acute Coronary Syndrome Study database, we evaluated 1,124 consecutive patients who were hospitalized within 48 hours of onset of symptoms of AMI from January to December 2002. There was a close relation between serum UA concentration and Killip's classification. Patients who developed short-term adverse events had high UA concentrations. Serum UA levels, Killip's class, age, and peak creatine phosphokinase level were significant predictors of long-term mortality. The hazard ratio for patients in the highest quartile of UA was 3.7 compared with those in the lowest quartile for death after AMI after adjustment for independent factors that were related to mortality. The combination of the best UA cutoff (447 micromol/L) for predicting survival based on receiver-operating characteristics analysis and Killip's class significantly predicted the prognosis of acute and long-term AMI-related complications. In conclusion, our results suggest that hyperuricemia after AMI is associated with the development of heart failure. Serum UA level is a suitable marker for predicting AMI-related future adverse events, and the combination of Killip's class and serum UA level after AMI is a good predictor of mortality in patients who have AMI. 相似文献
79.
Expression of GPIV and Naka antigen on monocytes in Naka -negative subjects whose platelets lack GPIV
Hironori Take Hirokazu Kashiwagi Yoshiaki Tomiyama Shigenori Honda Yumiko Honda Hajime Mizutani Takayasu Furubayashi Takahiro Karasuno Tetsuo Nishiura Yoshio Kanayama Yoshiyuki Kurata Yuji Matsuzawa 《British journal of haematology》1993,84(3):387-391
Summary. The platelet antigen Naka was once considered to be a platelet-specific alloantigen and is carried on platelet membrane glycoprotein (GP) IV. Recent studies suggest that Naka -negative subjects lack platelet GPIV. GPIV is an important adhesive receptor and expressed on the surface of monocytes as well as of platelets. In the present study, flow cytometry was used to detect GPIV and Naka antigen on the surface of monocytes. Naka antigen was expressed on monocytes as well as on platelets in Naka -positive subjects ( n = 6) (P-GPIV-positive subjects). To our surprise, monocytes of Naka -negative subjects ( n = 7) (P-GPIV-negative subjects) having no anti-Naka antibody in their serum expressed GPIV and Naka antigen to almost the same degree as did the monocytes of P-GPIV-positive subjects. Competitive experiments using OKM5 (a monoclonal antibody against GPIV) and anti-Naka antibody showed that the epitope of anti-Naka antibody on monocytes was very close to that of OKM5. In two P-GPIV-negative subjects having anti-Naka antibody in their serum, GPIV and Naka antigen were not expressed on the surface of either monocytes or platelets. These results indicate that the GPIV molecules and Naka antigen are expressed on the surface of monocytes in the majority of P-GPIV-negative subjects, but that in a very few P-GPIV-negative subjects neither GPIV nor Naka antigen is expressed on the surface of their monocytes. We hypothesize that P-GPIV-negative subjects who carry neither GPIV nor Naka antigen on their monocytes produce anti-Naka antibody as a result of transfusion or pregnancy. 相似文献
80.
El-Samad H Kurata H Doyle JC Gross CA Khammash M 《Proceedings of the National Academy of Sciences of the United States of America》2005,102(8):2736-2741
Molecular biology studies the cause-and-effect relationships among microscopic processes initiated by individual molecules within a cell and observes their macroscopic phenotypic effects on cells and organisms. These studies provide a wealth of information about the underlying networks and pathways responsible for the basic functionality and robustness of biological systems. At the same time, these studies create exciting opportunities for the development of quantitative and predictive models that connect the mechanism to its phenotype then examine various modular structures and the range of their dynamical behavior. The use of such models enables a deeper understanding of the design principles underlying biological organization and makes their reverse engineering and manipulation both possible and tractable The heat shock response presents an interesting mechanism where such an endeavor is possible. Using a model of heat shock, we extract the design motifs in the system and justify their existence in terms of various performance objectives. We also offer a modular decomposition that parallels that of traditional engineering control architectures. 相似文献