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   34420篇
  免费   1766篇
  国内免费   153篇
耳鼻咽喉   433篇
儿科学   645篇
妇产科学   608篇
基础医学   4682篇
口腔科学   1224篇
临床医学   2690篇
内科学   8181篇
皮肤病学   910篇
神经病学   2598篇
特种医学   1315篇
外科学   5440篇
综合类   234篇
一般理论   4篇
预防医学   1134篇
眼科学   549篇
药学   2310篇
中国医学   59篇
肿瘤学   3323篇
  2022年   367篇
  2021年   633篇
  2020年   303篇
  2019年   466篇
  2018年   635篇
  2017年   474篇
  2016年   533篇
  2015年   612篇
  2014年   805篇
  2013年   913篇
  2012年   1421篇
  2011年   1565篇
  2010年   841篇
  2009年   791篇
  2008年   1393篇
  2007年   1486篇
  2006年   1496篇
  2005年   1516篇
  2004年   1519篇
  2003年   1444篇
  2002年   1439篇
  2001年   1241篇
  2000年   1395篇
  1999年   1222篇
  1998年   424篇
  1997年   300篇
  1996年   313篇
  1995年   283篇
  1994年   253篇
  1993年   237篇
  1992年   812篇
  1991年   769篇
  1990年   689篇
  1989年   702篇
  1988年   682篇
  1987年   673篇
  1986年   679篇
  1985年   599篇
  1984年   433篇
  1983年   359篇
  1979年   342篇
  1978年   236篇
  1977年   206篇
  1975年   202篇
  1974年   226篇
  1973年   208篇
  1972年   198篇
  1971年   209篇
  1970年   205篇
  1969年   227篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Ten patients with severe hematologic malignancies (four with acute leukemia, three with multiple myeloma, one with prolymphocytic leukemia, one with malignant lymphoma and one with blastic crisis of chronic myelogenous leukemia) developed respiratory failure during the period between April 1986 and May 1990. Clinically, the patients manifested high-fever, dyspnea refractory to oxygen therapy, diffuse pulmonary rales and severe hypoxemia without evidence of cardiogenic pulmonary edema. Chest roentgenograms displayed diffuse alveolar infiltrates. Respiratory failure occurred as early as 48 hours and as late as 66 days after the administration of intensive anti-neoplastic chemotherapy. At that time leukocyte count was between 100/microliters and 54,900/microliters. Marked leukocytosis was observed in two patients with AML and PLL. Respiratory failure was preceded by sepsis in one patient with AML and by pneumonia in nine patients. DIC was diagnosed in four patients. All patients treated with high dose methyl prednisolone (mPSL) within 12 hours after the onset of respiratory failure. Only one patient required assisted ventilation. High dose mPSL had significant effect on seven of ten patients. But three patients died from progressive respiratory failure, sepsis, pneumonia and multi-organ failure.  相似文献   
992.
Measles‐rubella‐mumps vaccination is routine in many countries, but the mumps vaccine remains voluntary and is not covered by insurance in Japan. A 5‐year‐old Japanese boy who had not received the mumps vaccine was affected by mumps parotitis. Several days later, he presented with various neurological abnormalities, including akinesia, mutism, dysphagia, and uncontrolled respiratory disorder. Mumps encephalitis was diagnosed. Despite steroid pulse and immunoglobulin treatment, the disease progressed. Magnetic resonance imaging showed necrotic changes in bilateral basal ganglia, midbrain, and hypothalamus. At 1 year follow up, he was bedridden and required enteral feeding through a gastric fistula and tracheostomy. Mumps vaccination should be made routine as soon as possible in Japan, because mumps encephalitis carries the risk of severe sequelae.  相似文献   
993.
994.
995.
BACKGROUND & AIMS: Percutaneous radiofrequency ablation is a recently introduced treatment for hepatocellular carcinoma, whereas ethanol injection is now a standard therapy. We compared their long-term outcomes. METHODS: Two hundred thirty-two patients with hepatocellular carcinoma who had 3 or fewer lesions, each 3 cm or less in diameter, and liver function of Child-Pugh class A or B were entered onto a randomized controlled trial. The primary end point was survival, and the secondary end points were overall recurrence and local tumor progression. RESULTS: One hundred eighteen patients were assigned to radiofrequency ablation and 114 to ethanol injection. The number of treatment sessions was smaller (2.1 times vs 6.4 times, respectively, P < .0001) and the length of hospitalization was shorter (10.8 days vs 26.1 days, respectively, P < .0001) in radiofrequency ablation than in ethanol injection. Four-year survival rate was 74% (95% CI: 65%-84%) in radiofrequency ablation and 57% (95% CI: 45%-71%) in ethanol injection. Radiofrequency ablation had a 46% smaller risk of death (adjusted relative risk, 0.54 [95% CI: 0.33-0.89], P = .02), a 43% smaller risk of overall recurrence (adjusted relative risk 0.57 [95% CI: 0.41-0.80], P = .0009), and an 88% smaller risk of local tumor progression (relative risk, 0.12 [95% CI: 0.03-0.55], P = .006) than ethanol injection. The incidence of adverse events was not different between the 2 therapies. CONCLUSIONS: Judging from higher survival but similar adverse events, radiofrequency ablation is superior to ethanol injection for small hepatocellular carcinoma.  相似文献   
996.
OBJECTIVE: The serum IgA/C3 ratio might be considered to serve as a diagnostic marker for patients with IgA nephropathy (IgAN), but its value as a marker of the severity of histological lesions or prognosis is unknown. METHODS: We studied the serum IgA/C3 ratio, using standardized reference material, in 86 patients with IgAN and in 32 with non-IgAN. The patients with IgAN were divided according to the severity of histological lesions (mild IgAN, n=29 and severe IgAN, n=57) based on Japanese clinical guidelines. RESULTS: The serum IgA level was significantly higher, while its C3 level was lower in patients with severe IgAN compared to those with non-IgAN. However, these levels were not different between patients with mild IgAN and non-IgAN. In contrast, the serum IgA/C3 ratio obviously differed among the three groups (2.47+/-0.96 vs. 3.63+/-1.44 vs. 4.72+/-1.86; p<0.01, ANOVA). Kaplan-Meier analysis of the patients with IgAN classified according to the mean serum IgA/C3 ratio revealed that the group with high serum IgA/C3 (4.5 and above) had a significantly poorer renal outcome (p<0.05, log-rank test), since the cumulative renal survival rate at 5 years was 84.4% vs. 100%. The ratio (%) of patients with severe IgAN in whom hematuria disappeared, was significantly higher in the low, than in the high serum IgA/C3 group (41.9% vs. 15.4%; p<0.05, t-test). CONCLUSION: The serum IgA/C3 ratio appears to reflect the histological severity of IgAN and could serve as a marker of the progression of IgAN.  相似文献   
997.
998.
999.
1000.
A clinical grade prototype of posterior multifunctional Jones matrix optical coherence tomography (JM-OCT) is presented. This JM-OCT visualized depth-localized birefringence in addition to conventional cumulative phase retardation imaging through local Jones matrix analysis. In addition, it simultaneously provides a sensitivity enhanced scattering OCT, a quantitative polarization uniformity contrast, and OCT-based angiography. The probe beam is at 1-μm wavelength band. The measurement speed and the depth-resolution were 100,000 A-lines/s, and 6.6 μm in tissue, respectively. Normal and pathologic eyes are examined and several clinical features are revealed, which includes high birefringence in the choroid and lamina cribrosa, and birefringent layered structure of the sclera. The theoretical details of the depth-localized birefringence imaging and conventional phase retardation imaging are formulated. This formulation indicates that the birefringence imaging correctly measures a depth-localized single-trip phase retardation of a tissue, while the conventional phase retardation can provide correct single-trip phase retardation only for some specific types of samples.OCIS codes: (170.4500) Optical coherence tomography, (170.4460) Ophthalmic optics and devices, (110.5405) Polarimetric imaging, (120.5410) Polarimetry, (170.4470) Ophthalmology, (110.4500) Optical coherence tomography  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