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   54085篇
  免费   4483篇
  国内免费   2140篇
耳鼻咽喉   460篇
儿科学   1347篇
妇产科学   384篇
基础医学   6823篇
口腔科学   2512篇
临床医学   4607篇
内科学   7082篇
皮肤病学   255篇
神经病学   2082篇
特种医学   3147篇
外国民族医学   9篇
外科学   13867篇
综合类   7517篇
现状与发展   4篇
预防医学   2449篇
眼科学   605篇
药学   2840篇
  15篇
中国医学   1596篇
肿瘤学   3107篇
  2024年   96篇
  2023年   624篇
  2022年   1324篇
  2021年   1649篇
  2020年   1488篇
  2019年   1496篇
  2018年   1559篇
  2017年   1389篇
  2016年   1629篇
  2015年   1806篇
  2014年   3145篇
  2013年   3510篇
  2012年   2785篇
  2011年   3205篇
  2010年   2729篇
  2009年   2879篇
  2008年   2851篇
  2007年   2900篇
  2006年   2726篇
  2005年   2791篇
  2004年   2337篇
  2003年   1986篇
  2002年   1575篇
  2001年   1357篇
  2000年   1288篇
  1999年   1088篇
  1998年   861篇
  1997年   885篇
  1996年   763篇
  1995年   703篇
  1994年   619篇
  1993年   483篇
  1992年   466篇
  1991年   407篇
  1990年   344篇
  1989年   277篇
  1988年   286篇
  1987年   239篇
  1986年   240篇
  1985年   285篇
  1984年   226篇
  1983年   161篇
  1982年   190篇
  1981年   174篇
  1980年   158篇
  1979年   157篇
  1978年   135篇
  1977年   118篇
  1976年   81篇
  1973年   50篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
本文总结了14例应用刮治和自体骨移植术治疗大型牙源性角化囊肿的方法,14例植骨均成活,4例术后囊肿复发,再次手术,指出:与骨断切除治疗大型角化囊肿的方法比较,此法最大的优点是有利于保持患者面容和咀嚼功能,并对大型角化囊肿的手术原则,自体骨移植问题及手术注意事项进行了讨论。  相似文献   
72.
Melorheostosis is a benign sclerosing dysplasia with a very unusual and characteristic roentgenographic appearance. We reported a patient with melorheostosis in the left lower extremity followed up for 14 years. Although the extraosseous lesions only slightly enlarged, the bone scintigraphy showed the activity of the metabolism to be still high.  相似文献   
73.
Two iliac crest needle biopsies were taken from a 43-year-old lead-poisoned woman during and after completion of a Ca-EDTA treatment. By atomic absorption spectroscopy the first and second biopsy were found to contain 56, respectively 41.6 g lead/g wet tissue. In both biopsies 36% of the lead was extractable in 0.1 N HCl. Electron microbeam X-ray analysis proved to have too low sensitivity for quantitation of the lead in these biopsies. Laser microbeam mass analysis (LAMMA), performed only on the second biopsy, revealed a high and fairly constant residual lead concentration in all bone marrow cell nuclei (approximately 55 g/g) and a low lead concentration in the cytoplasm of the same cells (4–12 (g/g). The extracellular bone matrix lead was greatly concentrated in the superficial 3–6 m osteoid zone of the bony trabeculae and totally absent from deeper parts of the mineralized matrix. The LAMMA results are in good agreement with those of subcellular fractionation experiments and atomic absorption spectroscopy, provided that the relative volume fraction of nucleus and cytoplasm is accounted for. The high residual osteoid lead after completed chelation therapy indicates that lead has a stronger affinity for the organic than the mineral components of bone matrix.  相似文献   
74.
This paper reviews the literature on the role of dietary fat in calorie intake and body weight gain in humans and laboratory animals. An overview of 40 animal studies which compared growth on high-fat (HF) and high-carbohydrate (HC) solid/powdered diets indicated that the HF diet elicited greater weight gain in 33 out of 40 studies. Enhanced growth on the HF diet was often, but not exclusively, attributable to greater caloric intake. Additional evidence for the growth-enhancing effect of HF diets emerges from "diet option" and "supermarket" feeding studies in rats, and experimental and epidemiological studies in humans. Three principal factors that contribute to the different responses to HF and HC diets are (a) caloric density, (b) sensory properties and palatability, and (c) postabsorptive processing. It is concluded that both calorie intake and metabolic energy expenditure are biased towards weight gain when a HF diet is consumed, and that the high caloric density of high-fat diets plays a primary role in weight gain. Humans may be biologically predisposed to gain weight when a HF diet is consumed.  相似文献   
75.
Early erythroid precursors were studied in human bone marrow smears to provide more information on small proerythroblasts--"microproerythroblasts"--using a silver reaction to demonstrate silver stained nucleolar organizer regions (AgNORs) and light microscopic densitometry of large irregularly shaped nucleoli and cytoplasm stained for RNA. No significant differences were found for the density of such nucleoli and basophilic cytoplasm between characteristic large proerythroblasts with a nuclear diameter larger that 9 microm (K2 and K1 erythroblasts) and small proerythroblasts--"microproerythroblasts" representing a subpopulation of K1/2 erythroblasts (early basophilic erythroblasts), which are characterized by a smaller nuclear diameter. In addition, large irregularly shaped nucleoli of "microproerythroblasts" possessed numerous silver stained particles representing AgNORs similar to those of large proerythroblasts. The number of AgNORs in "microproerythroblasts" was slightly, but significantly, smaller than that in large characteristic proerythroblasts.  相似文献   
76.
OBJECTIVE: To examine psychosocial predictors of distress (mood disturbance, perceived stress, caregiver burden) in parents of children undergoing stem cell or bone marrow transplantation (BMT). METHOD: Measures of prior illness experiences, premorbid child behavior problems, family environment, social support, and parental coping behavior were obtained from the resident parents of 151 children prior to the children's admission for BMT. Parents subsequently completed assessments of their mood disturbance, perceived stress, and caregiving burden on a weekly basis through week +6 post-BMT, and then monthly through month +6 post-BMT. RESULTS: Significant changes were observed in parental distress across the course of BMT. After correcting for demographic and medical factors, several significant predictors of parental distress trajectories were identified, including prior parent and patient illness-related distress, premorbid child internalizing behavior problems, the family relationship dimensions of the family environment, and parental avoidant coping behaviors. Multivariable models were developed using a hierarchical modeling approach. The best-fit model accounted for approximately 50% of the variance in parental global distress. CONCLUSIONS: Subgroups of parents at higher risk for increased distress during the acute phase of transplant have been identified. These findings can help target parents who may be in greater need of intervention aimed at reducing transplant-related distress.  相似文献   
77.
分析47例骨髓穿刺干抽的临床和病理改变,干抽占同期1319例骨穿的3.6%。根据骨髓细胞的密度和间质纤维增殖的程度,把干抽的原因分为4类:高细胞伴间质细胞增多者19例(42.2%);间质细胞增多者14例(31.1%);高细胞者8例(17.8%)及低细胞者4例(8.9%)。主要疾病为:急性淋巴细胞白血病(25.5%),急性非淋巴细胞白血病(17.0%),慢性白血病(14.9%),骨髓转移瘤(10.6  相似文献   
78.
Intrasinusoidal infiltration of bone marrow (BM) may accompany several malignant lymphoproliferative disorders. In small B-cell lymphomas, this pattern is considered specific for splenic marginal zone lymphoma (SMZL) when exclusive or prominent, although it may occur in other subtypes of non-Hodgkin's lymphomas (NHLs) as a minor feature. Here we report 2 cases of mantle cell lymphoma (MCL) with a prominent intrasinusoidal BM infiltration pattern. Both patients presented with massive splenomegaly and peripheral blood involvement characterized by markedly atypical lymphocytes, but no lymphadenopathy. The cytological features and the phenotype of the lymphoma cells were diagnostic of MCL. The malignant B cells showed coexpression of B-cell markers (CD20+ and CD79a+), CD5 antigen, and cyclin D1 by immunohistochemistry. We discuss the specificity of an intrasinusoidal growth pattern in the bone marrow, emphasizing the importance of using a broader immunohistochemical panel in the differential diagnosis of intrasinusoidal BM infiltration by NHL.  相似文献   
79.
Thirty-two women with polycystic ovary syndrome (PCOS) wereallocated to two antiandrogen treatment regimens; 28 women completedthe trial. Twenty women were treated with ethinyloestradioland cyproterone acetate (EO-CA) cyclically for 6 months andeight women were treated with the gonadotrophin releasing hormone(GnRH) analogue, goserelin for 6 months. Effects on hirsutism,insulin sensitivity (estimated by glucose clamp technique),blood lipids and hormones were measured. Women treated withEO-CA showed a reduction in hirsutism (P <0.05), and decreasedserum androgen concentrations (P <0.001) as well as reducedinsulin sensitivity (P <0.05). In women treated with goserelin,serum androgen concentrations also decreased (P <0.001),but there was no significant reduction of hirsutism. This group,however, showed an improved insulin sensitivity (P <0.05)despite an unchanged body mass index. Bone mineral density wasunaltered in both treatment groups. The reduction in androgenconcentrations caused by EO-CA was not paralleled by increasedinsulin sensitivity, most probably due to the effect of ethinyloestradiolper se. In contrast, the reduction in androgen concentrationsby goserelin was accompanied by an improved insulin sensitivity.  相似文献   
80.
We describe studies aimed at maximizing the effector mechanisms responsible for eliminating target erythrocytes from the circulation in a fully homologous opsonization system in vivo. The effects on the subsequent fate of target erythrocytes were examined in both normal and decomplemented rats preinjected with a variety of rat IgG monoclonal antibodies (mAb) directed against different epitopes on the RTlAa, the classical class I major histocompatibiliy complex antigen of the DA rat. In general, the clearance of both DA and (DA × PVG)F1 erythrocytes in normal rats preinjected with various pairs of noncompetitive mAb was very rapid when compared with the overall clearance patterns seen with individual antibodies. With all mAb combinations containing IgG2b or IgG2a, an intact complement system was an essential requirement for augmenting the initial clearance and promoting hepatic sequestration of these target cells. The removal of (DA × PVG)F1 erythrocytes, expressing half as much antigen, was considerably slower than the DA cells for each antibody pair tested although a notable degree of heterogeneity was observed in the overall behavior of both types of target cells with different mAb combinations. Our results suggest that the limiting effects of low antigen density on the target cells combined with the use of mAb of an isotype like the rat IgG2a can be overcome using pairs of mAb that recognize different epitopes on the same target antigen.  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