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   409篇
  免费   23篇
  国内免费   8篇
耳鼻咽喉   2篇
儿科学   18篇
妇产科学   3篇
基础医学   50篇
口腔科学   40篇
临床医学   34篇
内科学   55篇
皮肤病学   8篇
神经病学   23篇
特种医学   80篇
外科学   34篇
综合类   25篇
预防医学   10篇
眼科学   1篇
药学   24篇
中国医学   14篇
肿瘤学   19篇
  2023年   1篇
  2022年   3篇
  2021年   5篇
  2020年   7篇
  2019年   7篇
  2018年   7篇
  2017年   3篇
  2016年   11篇
  2015年   11篇
  2014年   14篇
  2013年   12篇
  2012年   12篇
  2011年   12篇
  2010年   19篇
  2009年   18篇
  2008年   13篇
  2007年   14篇
  2006年   18篇
  2005年   17篇
  2004年   12篇
  2003年   16篇
  2002年   13篇
  2001年   8篇
  2000年   7篇
  1999年   10篇
  1998年   26篇
  1997年   29篇
  1996年   18篇
  1995年   13篇
  1994年   19篇
  1993年   9篇
  1992年   4篇
  1991年   2篇
  1990年   5篇
  1989年   7篇
  1988年   8篇
  1987年   4篇
  1986年   6篇
  1985年   3篇
  1983年   1篇
  1982年   1篇
  1981年   6篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   4篇
  1975年   1篇
排序方式: 共有440条查询结果,搜索用时 15 毫秒
41.
Aims. This article aims to review the literature published to date on the types, current use, the biomechanical effects and adverse effects of maternity support belts for low back pain during pregnancy, to identify future research directions. Background. Lumbar/pelvic support belts are frequently recommended for the prevention and treatment of low back pain during pregnancy. Design. Systematic review. Methods. MEDLINE, CINAHL, the Cochrane Library and patents databases were electronically searched. Results. Maternity support belts belong to one of the four main types of maternity support garments, which are widely commercially‐available. Current research showed limited evidence in support of the commercial maternity products regarding the effectiveness in the prevention and/or treatment of low back pain during pregnancy, other than that from the manufacturers. However, potential stabilisation effect of maternity support belt was demonstrated in some studies. Adverse effects reported include increased pain, fetal heart rate changes, skin irritation and discomfort. Conclusions. There is insufficient scientific evidence to conclude that wearing maternity support belts reduces pregnancy‐related low back pain and/or pelvic girdle pain. Future research directions in the area of biomechanics and physiology are recommended. Relevance to clinical practice. This review provides comprehensive understanding of the effectiveness of maternity support belts for the relief of low back pain during pregnancy which will facilitate healthcare professionals in providing evidence‐based advice to their patients.  相似文献   
42.
43.
Summary.  A part of the 5′-noncoding region of echovirus type 9 isolates was sequenced, and an attempt was made for rapid virus detection in clinical samples obtained from 22 subjects hospitalized with aseptic meningitis. The sequence identity of 440-bp products amplified from the region by RT-PCR was 87.7% between the standard echovirus type 9(Hill strain) and the isolates. Specific IgM antibodies to Hill strain were positive in 45.5% by immunofluorescent antibody staining of virus-infected cells. A high detection rate of PCR products was observed in cerebrospinal fluids (CSFs; 54.5%) at admission, and in peripheral mononuclear cells (PMCs; 72.7%) at the end of hospitalization. Viral genomes were detectable for 2 days in serum samples, and for 6 days in PMC samples after onset of disease. When specific IgM antibody titers were less than 1:40, the amplification rate of viral genome from serum samples was 50.0%. These results indicate that the combination of specific IgM determination and viral genome amplification from CSFs will be a rapid and reliable method for early diagnosis. Received July 29, 1996 Accepted September 30, 1996  相似文献   
44.
Cation‐specific epithelial receptors on the tongue have been well demonstrated. However, active regions along the nucleus of the solitary tract (NST) for cations Na+, K+, NH4+ are still unclear, even though the best responses of NST neurons to taste stimuli vary depending on the cell. In the present study, the spatial distribution patterns of cation‐specific active regions in the NST are investigated. The tongues of urethane‐anesthetized Sprague‐Dawley rats (n = 25) were stimulated with artificial saliva (control), 0.5 M NaCl, 1.0 M NaCl, 0.5 M KCl, and 0.3 M NH4Cl. Then, the three‐dimensional positions of c‐Fos‐like‐immunoreactive (cFLI) cells in the NST were generated. The spatial distributions of cFLI cells in the NST were compared among five taste stimulations. cFLI cells were observed throughout the NST, irrespective of the stimulus; however, the intermediate‐medial central regions of the NST had higher numbers of cFLI cells than the other regions in all taste stimulations. Analysis of images revealed that the activated regions in the NST differed significantly depending on the cations. The intermediate‐dorsal‐central region and the caudal‐ventral region were activated by a 0.5 M concentration of sodium, the rostral‐ventral region and the intermediate‐dorsal/ventral region were activated by a 1.0 M concentration of sodium, the intermediate‐dorsal/ventral region was activated by potassium ions, and the rostral‐ventral region and the intermediate‐ventral central region were activated by ammonium ions. These results suggest that the responses of NST cells to cation salt ions are regulated differentially. © 2014 Wiley Periodicals, Inc.  相似文献   
45.
46.
The plasminogen activation system is one of the enzyme systems held responsible for bone and cartilage degradation in rheumatoid arthritis (RA). In this study, we evaluated the effect of tranexamic acid (TEA), an inhibitor of plasminogen activation, on urinary collagen cross-link excretion and radiological joint damage in rat adjuvant arthritis (AA) and on urinary collagen cross-link excretion in patients with RA. In the animal study, adjuvant arthritis was induced in male Lewis rats. From day 7 onward, high-dose TEA (500 mg/kg body weight, once daily) or placebo was administered orally. Study groups consisted of TEA-treated normal rats (C + TEA), placebo-treated normal rats (C + plac), AA rats treated with TEA (AA + TEA) or with placebo (AA + plac). To monitor joint destruction, urinary collagen cross-link excretion (pyridinoline, HP; deoxypyridinoline, LP) was measured by high-performance liquid chromatography at days 14 and 21. Radiological evaluation of joints was performed at day 21. In the patient study, TEA was administered to nine patients with RA as adjuvant medication (approximately 20 mg/kg body weight, three times daily) for 12 weeks. Urinary HP and LP excretion levels were measured before and during TEA treatment, and 4 weeks after the cessation of TEA treatment. In AA + TEA rats, a significant reduction of HP and a tendency towards a reduction of LP excretion were found compared with AA + plac rats (P < 0.05), at day 14, whereas the HP/LP ratio did not change. No difference was observed in HP, LP excretion, HP/LP ratio and radiological damage score between the TEA- and placebo-treated AA rats at day 21. In RA patients, a significant reduction of HP and LP excretion was found during the TEA treatment period (P < 0.05). After the cessation of TEA treatment, HP and LP excretion increased towards baseline levels. No effect on disease activity was observed. The plasmin antagonist TEA reduced the excretion of collagen pyridinoline cross-links in both experimental and rheumatoid arthritis. As such, this study not only supports the involvement of the plasminogen activation system in the destructive phase of arthritis, but also suggests a beneficial effect of therapeutic strategies directed against inhibition of matrix proteolysis.   相似文献   
47.
The origin of low-grade mucosa-associated lymphoid tissue (MALT)-type B- cell lymphoma is still unclear. Using a novel two-step procedure, we have sequenced the Ig VH genes expressed by cells from four patients with gastric low-grade MALT-type lymphoma. The nucleotide sequences of the complementarity determining region 3 (CDR3) of the genomic DNA were first amplified using consensus oligonucleotide primers, then sequenced. Based on the CDR3 sequence amplified from each MALT lymphoma, individual tumor-specific primers were synthesized and used directly in the polymerase chain reaction (PCR) to analyze the sequences of their Ig heavy-chain variable region. When compared with the germ-line sequence, many nucleotide substitutions, mainly in the CDRs, were found in the variable gene sequences of the four MALT lymphomas. The mutations showed a high replacement-to-silent ratio and were distributed in a way which suggested that the tumor cells had been positively selected through their antigen receptor. Our findings indicate that the MALT-type lymphoma B cells are hypermutated postgerminal center lymphocytes that have undergone antigen selection.  相似文献   
48.
A bleeding disorder with absent collagen-induced platelet aggregation and adhesion has been described in a patient whose platelets failed to express surface glycoprotein Ia. We studied the interaction of her platelets with subendothelium in an annular perfusion chamber and the interaction with purified human collagen type III in a rectangular perfusion system under flow conditions. Platelet adherence was almost completely absent both at low and high shear rates. The few platelets which adhered remained in the contact stage without subsequent spreading and aggregate formation. Addition of a monoclonal antibody, which was directed against the von Willebrand moiety of FVIII-VWF, to the blood, completely abolished platelet adherence at high shear rates and had a partial effect at low shear rates. These data indicate that von Willebrand factor plays a role in the initial attachment (contact stage) of platelets to subendothelium. We conclude that the bleeding disorder and excessively prolonged bleeding time in our patient are caused by a new specific defect of the platelet-vessel wall interaction.  相似文献   
49.
A 35-year-old black man with end-stage renal disease from biopsy-proven focal segmental glomerulosclerosis developed worsening function of his renal allograft 160 days after living related donor renal transplantation. Renal biopsy showed necrotizing and crescentic glomerulonephritis (NCGN) and presence of intraglomerular viral inclusions confirmed by immunocytochemical stain and in situ hybridization techniques to be cytomegaloviral in origin. Electron microscopy showed no immune complexes, and workup for other causes of NCGN was negative. The patient was treated with ganciclovir without other changes in his immunosuppressive regimen. After 8 weeks of ganciclovir therapy, a second renal transplant biopsy showed resolution of the glomerular process and disappearance of the cytomegalovirus (CMV) inclusions. The resolution of the glomerular process with treatment for CMV infection, and without other change in therapy, strongly supports a causative link between CMV and NCGN in this patient. This case represents the first report of CMV-associated NCGN in a renal transplant patient.  相似文献   
50.
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