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   898篇
  免费   50篇
  国内免费   1篇
耳鼻咽喉   66篇
儿科学   14篇
妇产科学   10篇
基础医学   155篇
口腔科学   13篇
临床医学   47篇
内科学   143篇
皮肤病学   50篇
神经病学   57篇
特种医学   15篇
外科学   130篇
综合类   1篇
预防医学   15篇
眼科学   3篇
药学   81篇
中国医学   2篇
肿瘤学   147篇
  2023年   3篇
  2022年   15篇
  2021年   16篇
  2020年   3篇
  2019年   14篇
  2018年   25篇
  2017年   16篇
  2016年   20篇
  2015年   32篇
  2014年   27篇
  2013年   35篇
  2012年   44篇
  2011年   27篇
  2010年   27篇
  2009年   19篇
  2008年   41篇
  2007年   35篇
  2006年   36篇
  2005年   34篇
  2004年   35篇
  2003年   43篇
  2002年   44篇
  2001年   48篇
  2000年   33篇
  1999年   22篇
  1998年   17篇
  1997年   10篇
  1996年   12篇
  1995年   5篇
  1994年   5篇
  1993年   8篇
  1992年   17篇
  1991年   22篇
  1990年   11篇
  1989年   15篇
  1988年   18篇
  1987年   19篇
  1986年   16篇
  1985年   19篇
  1984年   8篇
  1983年   9篇
  1982年   6篇
  1980年   5篇
  1979年   3篇
  1978年   3篇
  1976年   3篇
  1972年   3篇
  1971年   4篇
  1969年   7篇
  1968年   3篇
排序方式: 共有949条查询结果,搜索用时 109 毫秒
61.
Bicarbonate and nitric oxide levels are important humoral factors in the blood and are affected by the human body's physical condition. There are few reports, however, on changes in blood bicarbonate and nitric oxide levels during exercise and rest. Since urinary bicarbonate and nitric oxide metabolites reflect the levels of bicarbonate and nitric oxide in the blood, we studied circadian changes in 6 female athletes by monitoring their urinary pH and their levels of urinary bicarbonate and nitric oxide metabolites. Measurements were taken during exercise, rest and sleep. Six female athletes participated in a 3-day team handball training camp where they followed a schedule of exercise, rest and sleep. Urinary samples were collected immediately before and after handball training, at bed-time and upon waking. The urinary pH and levels of urinary bicarbonate and nitric oxide metabolites, including nitrite and nitrate, were examined with a blood gas analyzer and a NOx analyzer. The samples collected after handball training, as compared to the samples taken before exercise, showed a decreased pH, a decrease in levels of bicarbonate and little change in NO metabolites. During rest, urinary bicarbonate, NO metabolites and pH increased markedly in all 6 subjects. The levels of urinary bicarbonate, NO metabolites and pH significantly decreased upon waking. This study took into account the subjects' various physiological conditions when considering the significance of their changes in urinary bicarbonate, NO metabolites and pH during the 3 day handball training program. There were significant circadian changes in the urinary pH, and in the levels of urinary bicarbonate and nitric oxide metabolites, in the athletes involved in the exercise, rest and sleep program at team handball camp.  相似文献   
62.
Although capillary barrier deterioration underlies major inflammatory lung pathology, barrier-enhancing strategies are not available. To consider hyperosmolar therapy as a possible strategy, we gave 15-minute infusions of hyperosmolar sucrose in lung venular capillaries imaged in real time. Surprisingly, this treatment enhanced the capillary barrier, as indicated by quantification of the capillary hydraulic conductivity. The barrier enhancement was sufficient to block the injurious effects of thrombin, TNF-alpha, and H2O2 in single capillaries, and of intratracheal acid instillation in the whole lung. Capillary immunofluorescence indicated that the hyperosmolar infusion markedly augmented actin filament formation and E-cadherin expression at the endothelial cell periphery. The actin-depolymerizing agent latrunculin B abrogated the hyperosmolar barrier enhancement as well as the actin filament formation, suggesting a role for actin in the barrier response. Furthermore, hyperosmolar infusion blocked TNF-alpha-induced P-selectin expression in an actin-dependent manner. Our results provide the first evidence to our knowledge that in lung capillaries, hyperosmolarity remodels the endothelial barrier and the actin cytoskeleton to enhance barrier properties and block proinflammatory secretory processes. Hyperosmolar therapy may be beneficial in lung inflammatory disease.  相似文献   
63.
Although anti-bromodeoxyuridine (BrdU) antibodies are used for detecting proliferating cells, they may stain proliferating cells in phases following the S-phase, except for G1. Anti-Ki67 antibodies are widely used for detecting proliferating cells in all phases of the cell cycle (G1-, S-, G2-, and M-phase), but not in resting cells (G0-phase). Anti-cyclin D1 antibodies are used to detect proliferating cells in the G1-phase. The present study investigated the olfactory epithelium of mice by double immunostaining using antibodies to BrdU, Ki67. cyclin D1, and cytokeratin 14 (CK14). The cells positive to the anti-BrdU antibody, the anti-Ki67 antibody, and the anti-cyclin D1 antibody differed from the cells positive to the anti-CK14 antibody. Thus, we confirmed that the proliferating cells in all the phases of the cell cycle, including the G1-phase, were globosal basal cells, which were the precursors of the olfactory cells.  相似文献   
64.
To clarify the mechanisms of age-related changes in the olfactory epithelium, we investigated age-related changes in epidermal growth factor receptors (EGFRs) in the epithelium. We examined 3 mice at each of the following stages: embryonal (embryonic days 14 and 16), neonatal (postnatal days 1 and 7), adult (postnatal weeks 5 and 12), and aged (postnatal years 1.5 to 2). The olfactory epithelium of each mouse was stained with sheep anti-human EGFR polyclonal IgG by an immunohistochemical method. The EGFRs were observed in all layers of the olfactory epithelium at the embryonal and neonatal stages. They were identified only in the basal layer of the olfactory epithelium at adult and aged stages, and the number of regions in which EGFRs were identified in the basal layer of the olfactory epithelium decreased in aged mice compared to adult mice. We believe that a decrease in EGFRs in the olfactory epithelium induces the inhibition of cell proliferation, with resultant atrophy of the olfactory epithelium.  相似文献   
65.
We investigated age-related changes in proliferating cells and epidermal growth factor receptors (EGFRs) in mouse olfactory epithelium using an immunohistochemical method with the antiproliferating cell nuclear antigen (PCNA) antibody and the antihuman EGFRs antibody. Many PCNA-positive cells occurred in the surface and basal layers of the olfactory epithelium in the embryonal and neonatal mice. However, only some PCNA-positive cells occurred in the basal layer of adult mice, and only a few presented in the basal layer of aged mice. EGFRs were observed in all layers of the olfactory epithelium at the embryonal and neonatal stages, but were not identified in the olfactory epithelium at the adult or aged stages. We believe that a decrease in EGFRs in the olfactory epithelium induces the inhibition of cell proliferation, with the resultant atrophy of the olfactory epithelium.  相似文献   
66.
Specific chromosomal abnormalities, such as del(7q), t(12;14), 12 trisomy, or the rearrangement of 6p, are seen in approximately 30% of uterine leiomyomas despite their benign status. We investigated the association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q, which is one of the most common chromosomal abnormalities in uterine leiomyomas. This study covered 29 women with uterine leiomyomas who were treated with a GnRH agonist before surgery. The volume of the largest myoma nodule was measured by means of MRI before and at 12 weeks after the beginning of GnRH agonist treatment, and the percentage of the reduction in volume was calculated. Genomic DNA was extracted from leiomyoma tissue and peripheral blood, and amplified by PCR using fluorescently-tagged oligonucleotide primers of twelve microsatellite loci on chromosome 7. The PCR products were analyzed for loss of heterozygosity (LOH) using an automated fluorescent DNA sequencer. Of the 29 informative tumors, five (17%) showed LOH with deletion of the common region, D7S491. The mean percentages of the reduction in volume of the largest myomas with LOH or without LOH were 32+/-13 and 18+/-58%, respectively (not significant). One tumor showing interstitial deletion of both alleles (homo-deletion) reduced in volume by 19%. Another tumor showing an extraband increased in volume by 13%. Although tumor specific chromosomal deletion suggested the existence of tumor suppressor genes in this region, there was no significant association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q.  相似文献   
67.
Preventive combined administration of granisetron 3 mg, methylprednisolone 500 mg, and metoclopramide 40 mg decreased the post-chemotherapy emesis from 56% in 68 control cases to 16% in 31 administered cases. All cases had non-small cell lung cancer and were treated with cisplatin 80 mg/m2, vindesine 3 mg/m2, and mitomycin C 8 mg/m2. YG character test in 23 cases revealed that emotional unstableness, characterized by the coupled rightward shift of the N (nervous) and I (inferior complex) components, was the important cause of emesis in those patients who failed to respond to the anti-emetic drugs shown above. Anti-emetic agents with different mechanisms and psychiatric counseling are needed in these emotionally unstable patients.  相似文献   
68.
Ovarian clear cell adenocarcinoma (OCCA) is known to be less responsive to cisplatin and most other anti-cancer drugs and to have a poorer prognosis than other ovarian cancers. We report a rare case of stage IIIc OCCA in a patient who has been treated postoperatively with cisplatin alone and continues to survive after 7.5 years. In this case, 25 mg/m2/day of cisplatin was administered for 5 consecutive days every 4 weeks. After remission, intermittent administration of cisplatin every 3 to 4 months was performed 8 times. This case suggests that induction and intermittent chemotherapy using consecutive low-dose cisplatin administration may be a useful treatment for OCCA.  相似文献   
69.
To investigate the role of cytokines in the pathogenesis of acute herpetic keratitis (HK), we examined the kinetics of cytokine expression in the corneas and the trigeminal ganglia (TG) of C57BL/6Cr (B6) mice after herpes simplex virus type 1 (HSV-1) infection and observed the influence of the targeted disruption of interferon-gamma (IFN-gamma) gene on the clinical course of HK and/or viral clearance. Following corneal infection with HSV-1 Amakata strain, all corneas developed a typical dendritic keratitis. Quantitative analysis using enzyme-linked immunosorbent assay (ELISA) revealed that the expression of interleukin-1alpha (IL-1alpha), IL-5, IL-6, and IFN-gamma in corneas and TGs significantly elevated immediately after infection, peaked between days 2 and 7 postinfection (p.i.), and then diminished. One exception was IFN-gamma, whose expression significantly persisted in the TGs until day 30 p.i. An additional experiment using IFN-gamma-/- (gko) mice revealed that there was no significant difference in the peak level of viral replication in corneas and TGs between gko and B6 mice, although gko mice showed a significant delay of virus clearance in both corneas and TGs (p < 0.005) and higher mortality rate than B6 mice after HSV-1 infection (p < 0.01). These data suggest that the production of proinflammatory cytokines closely correlates with the pathogenesis of HK, and that IFN-gamma plays an important role in enhancing viral clearance from the cornea and TG.  相似文献   
70.
Agents that disrupt functions of the endoplasmic reticulum (ER) induce expression of ER stress-response genes including ER chaperones. Increased expression of the major ER chaperone, Grp78, protects cells, including renal epithelial cells, from chemically induced injury and death in vitro. In this study, we determined if pharmacological manipulation of the ER stress-response gene is an effective strategy to protect the kidney from chemical stress in vivo. Treatment with trans-4,5-dihydroxy-1,2-dithiane (DTTox), a novel inducer of ER stress proteins, stimulated a time-and dose-dependent increase in Grp78 expression in the kidney, but it did not cause detectable injury. Furthermore, prior treatment with DTTox protected the proximal tubular epithelium against a subsequent challenge with the nephrotoxicant S-(1,1,2,2,-tetrafluoroethyl)-L-cysteine (TFEC). In contrast, activating a heat shock response did not have a protective effect. Prior treatment with DTTox did not reduce covalent binding of radiolabeled reactive metabolites of (35)S-TFEC to renal proteins, indicating that protection was not due to an effect on the metabolic activation of TFEC to the reactive metabolite(s) responsible for renal injury. Antisense grp78 expression in the renal epithelial cell line LLC-PK1 blocked the DTTox-induced Grp78 increase and ablated the protective effect against TFEC damage, indicating that the induction of grp78 expression and the ER stress response were critical for the protective effect of DTTox. These findings suggest that increased expression of Grp78 plays a major role in the protection of renal epithelial cells from reactive intermediate-induced chemical injury in vivo and that pharmacological manipulation is an effective strategy to prevent damage by some classes of nephrotoxicants.  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