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   4594篇
  免费   225篇
  国内免费   26篇
耳鼻咽喉   20篇
儿科学   67篇
妇产科学   40篇
基础医学   445篇
口腔科学   93篇
临床医学   292篇
内科学   1301篇
皮肤病学   115篇
神经病学   311篇
特种医学   127篇
外科学   805篇
综合类   9篇
预防医学   86篇
眼科学   76篇
药学   219篇
中国医学   11篇
肿瘤学   828篇
  2023年   26篇
  2022年   39篇
  2021年   91篇
  2020年   62篇
  2019年   68篇
  2018年   102篇
  2017年   106篇
  2016年   111篇
  2015年   95篇
  2014年   131篇
  2013年   151篇
  2012年   290篇
  2011年   301篇
  2010年   193篇
  2009年   175篇
  2008年   267篇
  2007年   337篇
  2006年   311篇
  2005年   311篇
  2004年   312篇
  2003年   255篇
  2002年   295篇
  2001年   62篇
  2000年   44篇
  1999年   62篇
  1998年   58篇
  1997年   47篇
  1996年   38篇
  1995年   37篇
  1994年   26篇
  1993年   32篇
  1992年   47篇
  1991年   28篇
  1990年   42篇
  1989年   41篇
  1988年   32篇
  1987年   26篇
  1986年   22篇
  1985年   28篇
  1984年   20篇
  1983年   13篇
  1982年   10篇
  1981年   7篇
  1980年   13篇
  1979年   9篇
  1978年   15篇
  1977年   9篇
  1974年   7篇
  1973年   9篇
  1971年   6篇
排序方式: 共有4845条查询结果,搜索用时 15 毫秒
21.
22.
Many researchers have evaluated the motions of the shoulder girdle, especially scapular and humeral motion. However, few reports exist that describe motions of the acromioclavicular joint. The purpose of the present study was to analyze the 3D kinematics of the acromioclavicular joint during arm abduction using 3D MR images obtained by a vertically open MRI. Fourteen shoulders of seven volunteers were examined in seven static positions from 0 degrees to the maximum abduction in a seated position. 3D surface models of the clavicle and scapula were created, and the movements of the acromioclavicular joint from 0 degrees to each position were calculated using the volume-based registration technique. From these calculations, the translations were evaluated and the rotational motions were analyzed using the concept of the screw axis. In the anteroposterior direction, the clavicle translated most posteriorly (-1.9 +/- 1.3 mm) at 90 degrees of abduction and most anteriorly (1.6 +/- 2.7 mm) at maximum abduction. In the superoinferior direction, the clavicle translated slightly superiorly (0.9 +/- 1.9 mm). When analyzing relative motion of the scapula with respect to the clavicle, the scapula generally rotated about a specific screw axis passing through the insertions of both the acromioclavicular and the coracoclavicular ligaments on the coracoid process. The average rotation was 34.9 +/- 8.4 degrees.  相似文献   
23.
Pyoderma gangrenosum is a rare, chronic, inflammatory ulcerative skin disease of unknown etiology and pathogenesis. It is often associated with systemic disease. We describe a patient with pyoderma gangrenosum associated with ulcerative colitis and aseptic abscesses of the subcutis and spleen, which have been rarely reported previously. These manifestations were cleared by combined therapy with minocycline hydrochloride and diaphenylsulfone.  相似文献   
24.
BACKGROUND: There have been few multicenter studies using intravascular ultrasound (IVUS) to assess the process of atherosclerosis in a Japanese population with hypercholesterolemia that is being treated with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors for control of low-density lipoprotein-cholesterol. METHODS AND RESULTS: An open-label multicenter study is planned to evaluate with IVUS whether treatment with rosuvastatin for 76 weeks results in regression of coronary artery atheroma volume in patients who have coronary heart disease (CHD) and hypercholesterolemia. Sample size is 200 subjects with CHD who are to undergo percutaneous coronary intervention. The planned duration is between October 2005 and October 2008. CONCLUSIONS: The COSMOS study will be the first multicenter cardiovascular study in a Japanese population and may provide new evidence on the effects of rosuvastatin on the progression of coronary atherosclerotic lesions.  相似文献   
25.
26.
The correlation of changes in cortical neuron activity with water content and local cerebral blood flow was investigated in cats with brain edema produced by air exposure. The further effect of high-dose methylprednisolone on these factors was studied. Six hours after exposure of the brain surface to air, the water content of the white matter significantly increased. The local blood flow of the cortex and white matter significantly decreased with significant suppression of cortical neural activity (direct cortical response), indicating that ischemia was responsible for neural suppression. A single, large dose of methylprednisolone (30 mg/kg, i.v.) at the beginning of air exposure significantly reduced brain edema of the cortex and white matter 12 h after air exposure and improved the local blood flow of the cortex. Methylprednisolone also caused a remarkable improvement in cortical neural activity. This steroid effect on cortical neural function may play a role in the rapid neurologic improvement observed with their use in addition to the effect on brain edema.  相似文献   
27.
Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) has been suggested to be sensitivity-limiting factors of 5-fluorouracil therapy in cancer patients. We conducted a large-scale population study on the activity of TS and DPD in patients with various solid tumors. A total of 2590 clinically removed tumors, consisting of 1112 colon, 724 gastric, 520 breast, and 236 non-small cell lung cancers, were provided to measure TS and DPD activity. TS activity in the gastric, colon, and non-small cell lung cancers was significantly higher than in matched non-cancerous tissue (P<0.0002), but there was no difference in TS expression between tumor and non-cancerous tissue from breast cancer patients. Gastric, breast, and non-small cell lung cancers showed significantly higher DPD activity than their corresponding non-cancerous tissues, but colon cancers did not. There was no correlation between TS activity and DPD activity, and thus each enzyme was considered to be an independent sensitivity-limiting factor for 5-fluorouracil therapy. The median TS activity and median DPD activity in all specimens including gastric, colorectal, breast, and non-small cell lung cancers tested were 0.041 and 110.1 pmol/mg protein, respectively. We classified each of the type of carcinoma into 4 groups by using the median activity of TS and DPD as the cutoff values: a low TS/low DPD group, high TS/low DPD group, low TS/high DPD group, and high TS/high DPD group. About 50% of the gastric, 47% of the colon, 70% of the breast and 30% of the non-small cell lung cancers had high TS activity, and 60% of the gastric, 40% of the colon, 48% of the breast, and 87% of the lung cancers had high DPD activity. Moreover, breast cancer was characterized by high TS activity and lung cancer by high DPD activity as compared with gastric and colon cancers, and their high activity levels may influence to the effectiveness of 5-fluorouracil against cancers of these organs. The results for expression of TS and DPD in clinically dissected tumors would be useful to estimate the efficacy of 5-fluorouracil in the treatment of cancer patients.  相似文献   
28.
Using 2-dimensional electrophoresis and ion-pair chromatography, we have identified elements of proliferating cell nuclear antigen (PCNA) multiprotein complexes that are reactive to antibodies in sera from patients with systemic lupus erythematosus. Among the various elements of the complexes, a 37 kDa protein (PI 8.5) that specifically reacted with SLE sera, but not with sera from patients with other connective tissue diseases, was identified as glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Immunoblot analysis showed that SLE sera reactive with the 37 kDa protein specifically reacted with GAPDH, as did anti-GAPDH mAbs. The purified autoantibodies to GAPDH from lupus serum showed both nuclear speckled and cytoplasmic staining patterns in immunofluorescence on Hep-2 cells. In addition, enzyme-linked immunosorbent assay (ELISA) revealed the presence of anti-GAPDH autoantibodies in 47% of lupus patients. Longitudinal analysis of the reactivity of lupus sera to PCNA complexes showed the autoimmune response to spread from GAPDH to other elements of PCNA complexes, and the presence of anti-GAPDH antibodies was significantly correlated with increased levels of serum PCNA. Taken together, these findings suggest that GAPDH interacting with PCNA in association with its cellular function is a novel autoantigen recognized by lupus sera, and that GAPDH thus plays an important role in the induction of autoimmune responses against the PCNA complex.  相似文献   
29.
Human endometrial stromal cells (ESC) can produce a variety of chemokines, especially after inflammatory stimulation. Interferon-gamma-inducible protein-10 (IP-10) is a potent chemoattractant for lymphocytes, and belongs to the family of non-ELR CXC chemokines. The expression of IP-10 in ESC after stimulation with interferon-gamma (IFN-gamma), interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), or lipopolysaccharide (LPS) was evaluated using an enzyme-linked immunosorbent assay and Northern blot analysis. A small amount of IP-10 protein was detected in the culture media of unstimulated ESC. The expression of IP-10 mRNA was detected in ESC. IFN-gamma, IL-1 beta, TNF-alpha and LPS significantly stimulated the expression of IP-10 mRNA and protein in ESC. These results suggest that the production of IP-10 by ESC is regulated by inflammatory mediators. The modulation of IP-10 concentrations in the local environment may contribute to the normal and pathological processes of human reproduction by regulating leukocyte trafficking in the endometrium.  相似文献   
30.
In the present study, we evaluated the potential of bradykinin (BK) to induce the release of neutrophil and monocyte chemotactic activity (NCA and MCA) and cytokines from an alveolar type II epithelial cell line, A549 cells. BK stimulated A549 cells to release NCA and MCA in a dose- and time-dependent manner (P < 0.001). Checkerboard analysis revealed that both NCA and MCA involved chemotactic and chemokinetic activity. Molecular sieve column chromatography showed three molecular weight masses (near 19 kd, 8 kd, and 400 d) for NCA and several molecular weight peaks (near 66 kd, 25 kd, 19 kd, 16 kd, and 400 d) for MCA. The release of NCA and MCA was inhibited by cycloheximide and lipoxygenase inhibitors (P < 0.01). The NCA and MCA were inhibited by leukotriene B4 (LTB4) receptor antagonist (P < 0.01), and the concentration of LTB4 was high enough for NCA and MCA. Antibodies to interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) attenuated NCA (P < 0.01), and antibodies to monocyte chemotactic protein-1 (MCP-1), G-CSF, and transforming growth factor (TGF)-β attenuated MCA (P < 0.01). The levels of IL-8, G-CSF, MCP-1, and TGF-β increased time dependently (P < 0.01). BK also stimulated the release of ILeukin-6 from A549 cells (P < 0.001). The receptors responsible for the release of NCA, MCA, and individual chemokines involved both BKB1 and BKB2 receptors. These data suggest that BK may stimulate alveolar type II pneumocytes to release inflammatory cytokines, which then may modulate the lung inflammation.  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