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   1631篇
  免费   78篇
  国内免费   2篇
耳鼻咽喉   26篇
儿科学   23篇
妇产科学   24篇
基础医学   258篇
口腔科学   74篇
临床医学   71篇
内科学   404篇
皮肤病学   26篇
神经病学   107篇
特种医学   79篇
外科学   201篇
综合类   6篇
预防医学   60篇
眼科学   140篇
药学   93篇
肿瘤学   119篇
  2023年   4篇
  2022年   11篇
  2021年   18篇
  2020年   8篇
  2019年   11篇
  2018年   17篇
  2017年   13篇
  2016年   21篇
  2015年   24篇
  2014年   64篇
  2013年   62篇
  2012年   56篇
  2011年   73篇
  2010年   48篇
  2009年   45篇
  2008年   88篇
  2007年   76篇
  2006年   74篇
  2005年   87篇
  2004年   77篇
  2003年   63篇
  2002年   64篇
  2001年   63篇
  2000年   51篇
  1999年   54篇
  1998年   22篇
  1997年   21篇
  1996年   25篇
  1995年   18篇
  1994年   12篇
  1993年   10篇
  1992年   46篇
  1991年   41篇
  1990年   30篇
  1989年   32篇
  1988年   29篇
  1987年   37篇
  1986年   32篇
  1985年   37篇
  1984年   25篇
  1983年   16篇
  1982年   11篇
  1981年   18篇
  1980年   9篇
  1979年   16篇
  1978年   7篇
  1977年   9篇
  1976年   8篇
  1975年   5篇
  1972年   4篇
排序方式: 共有1711条查询结果,搜索用时 15 毫秒
31.
BACKGROUND: A randomized, controlled clinical trial was conducted in 1991 to compare an intravenous megadose of methylprednisolone with a control drug (mecobalamin) for treating acute idiopathic optic neuritis. CASES: Sixty-six cases from 22 clinical centers throughout Japan were examined to evaluate the treatment on visual function parameters, such as visual acuity, visual field, color vision, contrast sensitivity, and critical flicker frequency. OBSERVATIONS: The methylprednisolone pulse treatment group showed faster recovery of visual function, particularly the visual acuity at 1 week (P<.05), Humphrey field analyzer mean deviation at 3 weeks (P<.05), and color vision at 1 week (P<.05). Recovery of contrast sensitivity at several different spatial frequencies was significant in the pulse treatment group at 1 (P<.01), 2 (P<.05), and 4 weeks (P<.05) after the start of treatment. Visual function test results at 12 weeks and 1 year were essentially the same in the two treatment groups. Side effects appeared more frequently in the pulse treatment group than in the control (P<.05). CONCLUSIONS: Pulse treatment does not appear effective for idiopathic optic neuritis even though visual function in the pulse treatment group of this trial recovered more quickly during the initial phase compared to the controls. More effective and specific treatment should be established for optic neuritis.  相似文献   
32.
BACKGROUNDS: Choroideremia is an X-linked hereditary eye disease that causes progressive degeneration of the choroid and retina and frequently leads to legal blindness in later life. Recent molecular genetic studies have revealed mutations involving the Rab escort protein (REP-1) gene localized at Xq 21. CLINICAL FEATURES: The clinical picture and rate of progression may vary among affected individuals in different families and within the same family. Usually, hemizygous males develop night blindness in their teenage years, followed by progressive peripheral visual field constriction and visual disability in late age. Heterozygous female carriers are mostly asymptomatic, but their fundi show characteristic pigment changes in the midperiphery closely resembling the fine mottling observed in the initial stage of the disease in males. MOLECULAR GENETICS: Assessment of the REP-1 gene in European and Japanese choroideremia patients has revealed a wide variety of mutations, including gross deletions and point mutations such as nonsense, frameshift, and splice-site mutations. All these mutations are thought to fail in intact REP-1 protein synthesis. CONCLUSIONS: The recent molecular studies may open a new chapter in the research on choroideremia and provide the groundwork for therapeutic potential as well as diagnosis and genetic counseling.  相似文献   
33.
· Background: Choroideremia (CHM) is an X-linked progressive dystrophy of the choroid, retinal pigment epithelium, and retina. Recently, the REP-1 gene was isolated and the causative mutations in the gene were detected in patients with CHM. In a previous study, we described a Japanese family with CHM who had a mutation in the REP-1 gene. In the present study, we performed extensive analysis of the REP-1 gene in patients with CHM from several institutions in Japan. · Methods: Twenty-six patients with CHM and 5 unaffected females from 22 independently ascertained families were examined. Exons 1–15 of the REP-1 gene were screened by single-strand conformation polymorphism. The DNA fragments suspected of any variations were directly sequenced. · Results: Fifteen different mutations, including one previously reported mutation, were detected in 18 families. In addition, carrier status was proven in four unaffected females found to be heterozygous for the mutant allele. · Conclusions: Fifteen different mutations of the REP-1 gene were detected in 18 Japanese families. There were no hot spots for the mutations and no missense mutations. The results show that REP-1 gene defects cause CHM in Japanese patients, and the mutations in these Japanese patients differed from the mutations reported for CHM patients in Europe, Canada, and America except for R267X and 1313delTC. These findings suggest that the mutations occurred independently in the Japanese patients. Received: 13 August 1998 Revised version received: 16 November 1998 Accepted: 9 December 1998  相似文献   
34.
We report a rare case of anterior mediastinal thymic cyst together with a thymoma and its intracystic dissemination. More attention should be given to intramural nodules, especially in patients with an anterior mediastinal thin wall cystic lesion.  相似文献   
35.
36.
37.
BackgroundLocomotive syndrome (LS) was proposed by the Japanese Orthopedic Association and refers to a scenario in which imminent future nursing care services will be required by elderly adults to manage the functional deterioration of their locomotive organs. It is a social imperative to clarify the risk factors and treatment strategy for LS. However, the relationship between LS and adult spinal deformity (ASD) in those who are treated with spinal corrective surgery remains largely unknown.MethodsForty consecutive patients who had ASD and underwent spinal surgery for their disorder were included in this study. Locomotive dysfunction was evaluated using the 25-item Geriatric Locomotive Function Scale-25 (GLFS-25) questionnaire and physical performance tests including the one-legged standing test, the two-step test, the stand-up test, the handgrip strength, and gait speed test which were measured preoperatively, 6 months after surgery, and 1 year after surgery.ResultsOf the patients with ASD treated surgically, 95% of them had LS preoperatively and LS prevalence decreased significantly 1 year after surgery by 67.5% compared with the preoperative rate. Among physical performance tests, the walking stride and one-legged standing test improved significantly after spinal corrective surgery. The GLFS-25 items for the domains of pain, mobility, and domestic life improved overall postoperatively, whereas items in the self-care domain did not and the item for difficulty in putting on and taking off trousers and pants worsened.ConclusionsSpinal corrective surgery significantly improved physical performance tests as well as the frequency and severity of LS in patients with ASD. However, some GLFS-25 items can worsen after surgery and require attention.  相似文献   
38.
To clarify the significance of newly appearing abnormal Q waves and their disappearance in patients with Kawasaki disease, regional myocardial perfusion and glucose metabolism at rest in the fasting condition were assessed by positron emission tomography (PET) with 13N-ammonia and 18F-fluorodeoxyglucose (FDG), and regional wall motion by left ventriculography in regions with persistent and transient abnormal Q waves in 14 patients. PET identified 3 groups of abnormal myocardial segments: segments with hypoperfusion without increased FDG uptake, those with hypoperfusion and increased FDG uptake, and those with normal perfusion and increased FDG uptake. Almost all the segments with persistent or transient abnormal Q waves had abnormal PET findings. PET demonstrated evidence of metabolic activity in 57% of segments with persistent abnormal Q waves and 67% of those with transient abnormal Q waves. Regional wall motion, scored from 0 (normal) to 4 (dyskinesia), was not significantly different between segments with persistent and transient abnormal Q waves (2.3 ± 1.3 vs 2.2 ± 1.2). The persistence of abnormal Q waves on serial electrocardiograms was significantly shorter in metabolically active than in inactive segments (19 ± 17 vs 92 ± 27 months). In conclusion, in patients with Kawasaki disease, the new appearance of abnormal Q waves is a reliable clue to the presence of ischemic myocardial injury and a high proportion of them are associated with metabolically active myocardial regions. The disappearance of abnormal Q waves does not necessarily mean the normalization of regional myocardial perfusion, metabolism or function, and their early disappearance may imply “viability” in the associated myocardial region.  相似文献   
39.
40.
Nb2 cell is a rat lymphoma cell line that responds to lactogens such as prolactin and human growth hormone (hGH) with an increased rate of proliferation. We explored the relationship between the biochemical events induced by hGH and its derivatives and their receptor binding activities. hGH stimulated RNA, DNA and protein synthesis of Nb2 cells as a function of time. Stimulation of RNA and protein was maximal at 2-3 h and 12 h, respectively, after the addition of hGH. DNA synthesis, measured by the rate of [3H]thymidine incorporation, reached a maximum after 18-h incubation with hGH. Stimulation of DNA synthesis was elicited by hGH in a dose-dependent manner between 0.45 and 45 pmol/l. The activity of the 20 K hGH variant in stimulating DNA synthesis was approx 30% of that of hGH. In contrast, S1-hGH, which lacks a sequence of ten amino acids (140-149) of hGH, showed a 3.2-fold greater activity than hGH. F1 (amino-terminal sequence 1-134 of hGH) was only 0.06% as active as hGH, and the activity of F2 (C-terminal 42 amino acid residue of hGH) was less than 0.01%. Both fragment 1-15 and 32-46 were without effect. The relative potencies of these hGH derivatives in stimulating DNA synthesis were similar to their relative abilities to inhibit [125I]hGH binding to lactogenic receptors on Nb2 cell. Nb2 cells provide a suitable model to study the relationship between receptor binding and the biochemical events induced by lactogens.  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