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   2904篇
  免费   178篇
  国内免费   15篇
耳鼻咽喉   73篇
儿科学   33篇
妇产科学   59篇
基础医学   298篇
口腔科学   50篇
临床医学   232篇
内科学   865篇
皮肤病学   39篇
神经病学   123篇
特种医学   99篇
外科学   540篇
综合类   18篇
预防医学   78篇
眼科学   13篇
药学   175篇
中国医学   7篇
肿瘤学   395篇
  2023年   32篇
  2022年   48篇
  2021年   80篇
  2020年   41篇
  2019年   49篇
  2018年   82篇
  2017年   49篇
  2016年   81篇
  2015年   69篇
  2014年   81篇
  2013年   82篇
  2012年   189篇
  2011年   178篇
  2010年   115篇
  2009年   87篇
  2008年   155篇
  2007年   139篇
  2006年   115篇
  2005年   119篇
  2004年   125篇
  2003年   121篇
  2002年   148篇
  2001年   64篇
  2000年   70篇
  1999年   90篇
  1998年   36篇
  1997年   35篇
  1996年   24篇
  1995年   21篇
  1994年   17篇
  1993年   13篇
  1992年   70篇
  1991年   58篇
  1990年   56篇
  1989年   38篇
  1988年   39篇
  1987年   33篇
  1986年   43篇
  1985年   34篇
  1984年   27篇
  1983年   17篇
  1982年   8篇
  1981年   16篇
  1980年   11篇
  1979年   15篇
  1978年   10篇
  1977年   12篇
  1975年   6篇
  1970年   5篇
  1969年   12篇
排序方式: 共有3097条查询结果,搜索用时 15 毫秒
81.
A liquid crystal laser using a polymer-stabilized simple cubic blue phase (BPII) platform has been scarcely reported because the polymer stabilization of a BPII is relatively difficult compared to that of a body-centered-cubic BP (BPI). In this study, we succeeded in fabricating a dye-doped polymer-stabilized BPII laser with wide operating-temperature ranges over 15 °C including room temperature. A narrow and sharp single laser peak with a full width at half maximum of approximately 2 nm was derived from the photonic band edge effect of the BPII-distributed feedback optical resonator. As a result, the laser emission was a circularly polarized light, which matched the chirality of the proposed pure BPII.

A dye-doped polymer-stabilized simple cubic liquid crystalline blue phase (BPII) laser with wide operating-temperature ranges over 15 °C including room temperature was fabricated.  相似文献   
82.
BACKGROUND Autotaxin(ATX) has been reported as a direct biomarker for estimating the evaluation of liver fibrosis. But available data on ATX as a useful biomarker for the complications of liver cirrhosis(LC) are scant.AIM To assess the clinical usefulness of ATX for assessing the complications of LC.METHODS This multicenter, retrospective study was conducted at six locations in Japan. We include patients with LC, n = 400. The ATX level was evaluated separately in men and women because of its high level in female patients. To assess the clinical usefulness of ATX for the complications of LC, the area under the curve(AUC) of ATX assessing for the severe complications was analyzed in comparison with the model for end-stage liver disease score, albumin-bilirubin(ALBI) score, fibrosis-4 index, and aspartate aminotransferase-to-platelet ratio index.RESULTS The mean age was 68.4 ± 11.4 years, 240 patients(60.0%) were male. A total of 213(53.3%) and 187(46.8%) patients were compensated and decompensated,respectively. The numbers of patients with varix rupture, hepatic ascites, and hepatic encephalopathy were 35(8.8%), 131(32.8%), and 103(25.8%),respectively. The AUCs of ATX in men for hepatic encephalopathy, hepatic ascites, and varix ruptures were 0.853, 0.816, and 0.706, respectively. The AUCs of ATX in women for hepatic encephalopathy, hepatic ascites, and varix rupture were 0.759, 0.717, and 0.697, respectively. The AUCs of ATX in men were higher than those in women, as were all the other biomarkers used to detect encephalopathy and varix ruptures. However, for detecting ascites, the AUC of ALBI in men was more effective than using ATX.CONCLUSION ATX in men was more effective than any other biomarkers for detecting hepatic encephalopathy and varix ruptures.  相似文献   
83.
Cognitive impairment has long been recognized as a complication of chronic kidney disease. However, there is little information available regarding regional cerebral blood flow (rCBF) in patients with peritoneal dialysis (PD). Therefore, we evaluated rCBF using brain single photon emission computed tomography (SPECT). We conducted a cross‐sectional study in our hospital. Eighteen consecutive PD patients who could visit the hospital by themselves without any history of stroke were examined by Technetium‐99 m‐labeled ethylcrysteinate dimer brain SPECT. An easy Z‐score imaging system (eZIS) was used to compare rCBF in PD patients with those in age‐matched healthy controls. We also evaluated cognitive dysfunction with the mini‐mental state examination (MMSE) questionnaire. Only one patient showed an MMSE score of 18 points, and the remaining 14 patients were considered as normal (MMSE ≥ 27), and three patients were considered to have mild cognitive impairment (24 ≤ MMSE ≤ 26). In all patients, rCBF in the posterior cingulated gyri, precunei, and parietal cortices was significantly decreased. The ratio of the reduction of rCBF in each region relative to that of rCBF across the whole brain correlated positively with the PD duration (r = 0.559; P < 0.05). The serum β2‐microglobulin level was significantly higher in patients who had a higher ratio of rCBF reduction compared with those with lower ratios. In conclusion, all PD patients in the present study had decreased rCBF irrespective of MMSE scores.  相似文献   
84.
Colloid osmotic pressure (COP) is important in calculating vascular permeability during hemodialysis (HD). However, few reports have directly measured COP in HD patients. Therefore, the currently published formulas may not be clinically optimal for predicting COP for HD patients. Here, the study aims were (i) to directly measure COP in HD patients and compare the measured and predicted COP values using four previously reported formulas, and (ii) to develop a formula for approximating COP using clinical parameters. We obtained 212 measured COP values using an osmometer; the average value was 22.0 ± 0.2 mm Hg. The predicted COP based on the four different formulas was positively correlated with the measured COP (0.87 < r < 0.89), but was significantly overestimated compared to it (P < 0.001). We also performed a stepwise analysis using serum albumin and non‐albumin protein concentrations and obtained the following simple formula for COP approximation: COP (mm Hg) = ?7.91 + 5.64 × albumin (g/dL) + 3.00 × non‐albumin proteins (g/dL). A positive linear correlation was observed between the measured COP and approximated COP using this formula (r = 0.90, P < 0.001). We calculated the mean Kr (plasma‐refilling coefficient) as a marker for determining dry weight in HD patients using the measured COP and approximated COP. No differences were observed between the mean Kr derived from the measured and approximated COP. We report here significant differences between measured and predicted COP values, and have devised a simple formula for COP approximation in HD patients.  相似文献   
85.
Primary squamous cell carcinoma is rarely observed, with a reported incidence of 0.04–0.07 % of all gastric cancers. An 81-year-old male underwent chemoradiotherapy for type 1 gastric cancer of the posterior wall of the cardiac region in 2005. The tumor disappeared after 1 year of therapy, following which an area of white epithelium, approximately 30 mm in diameter and continuous with the esophageal mucosa, became visible. Biopsy of the white epithelium indicated normal squamous epithelium. An elevated lesion was subsequently detected in the area of white epithelium on upper gastrointestinal endoscopy during a follow-up examination 5 years after therapy. As a biopsy of the same site indicated squamous cell carcinoma, we performed endoscopic submucosal dissection. Histopathological examination indicated high-grade fibrosis due to radiotherapy and showed a moderately differentiated squamous cell carcinoma invading the scarred portion. We describe a case where the developmental process of a squamous cell carcinoma was observed using endoscopy, including narrow band imaging with magnification. This carcinoma likely originated from squamous metaplasia that developed after chemoradiotherapy was administered for a gastric cancer.  相似文献   
86.
87.
Monoclonal antibody (mAb) drugs are desirable for the improvement of multiple myeloma (MM) treatment. In this study, we found for the first time that CD48 was highly expressed on MM plasma cells. In 22 out of 24 MM patients, CD48 was expressed on more than 90% of MM plasma cells at significantly higher levels than it was on normal lymphocytes and monocytes. CD48 was only weakly expressed on some CD34(+) haematopoietic stem/progenitor cells, and not expressed on erythrocytes or platelets. We next examined whether CD48 could serve as a target antigen for mAb therapy against MM. A newly generated in-house anti-CD48 mAb induced mild antibody-dependent cell-mediated cytotoxicity and marked complement-dependent cytotoxicity against not only MM cell lines but also primary MM plasma cells in vitro. Administration of the anti-CD48 mAb significantly inhibited tumour growth in severe combined immunodeficient mice inoculated subcutaneously with MM cells. Furthermore, anti-CD48 mAb treatment inhibited growth of MM cells transplanted directly into murine bone marrow. Finally and importantly, we demonstrated that the anti-CD48 mAb did not damage normal CD34(+) haematopoietic stem/progenitor cells. These results suggest that the anti-CD48 mAb has the potential to become an effective therapeutic mAb against MM.  相似文献   
88.
89.
90.
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