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   1073篇
  免费   80篇
  国内免费   6篇
耳鼻咽喉   14篇
儿科学   59篇
妇产科学   71篇
基础医学   149篇
口腔科学   31篇
临床医学   112篇
内科学   209篇
皮肤病学   25篇
神经病学   94篇
特种医学   110篇
外科学   107篇
综合类   17篇
预防医学   29篇
药学   85篇
肿瘤学   47篇
  2022年   4篇
  2021年   9篇
  2020年   9篇
  2019年   11篇
  2018年   17篇
  2017年   15篇
  2016年   12篇
  2015年   27篇
  2014年   24篇
  2013年   39篇
  2012年   41篇
  2011年   47篇
  2010年   48篇
  2009年   42篇
  2008年   37篇
  2007年   41篇
  2006年   44篇
  2005年   47篇
  2004年   31篇
  2003年   51篇
  2002年   41篇
  2001年   30篇
  2000年   35篇
  1999年   40篇
  1998年   40篇
  1997年   38篇
  1996年   41篇
  1995年   29篇
  1994年   25篇
  1993年   22篇
  1992年   13篇
  1991年   9篇
  1990年   14篇
  1989年   18篇
  1988年   22篇
  1987年   20篇
  1986年   14篇
  1985年   13篇
  1984年   9篇
  1983年   10篇
  1982年   8篇
  1981年   13篇
  1980年   5篇
  1979年   8篇
  1977年   5篇
  1976年   8篇
  1971年   4篇
  1947年   3篇
  1944年   2篇
  1907年   2篇
排序方式: 共有1159条查询结果,搜索用时 15 毫秒
91.
Inhibins and activins in pregnancy   总被引:3,自引:0,他引:3  
Human placenta, decidua, and fetal membranes are the major sites of production and secretion of inhibin A and activin A in maternal serum, amniotic fluid, and umbilical cord blood. These tissues also express follistatin-related gene and betaglycan, the binding proteins of activin A and inhibin A, respectively, recently identified. They show a different expression throughout pregnancy, suggesting new functional roles into gestational tissues. The availability of suitable assays for measuring inhibin A and activin A lead us the possibility to investigate their secretion in healthy pregnancy. In addition, several evidences underline the potential role and the clinical usefulness of their measurement in the diagnosis, prevention, prognosis and follow-up of different gestational pathologies such as: threatened abortion, placental tumors, hypertensive disorders of pregnancy, intrauterine growth restriction, fetal hypoxia. The measurement of inhibin A and activin A into the biological fluids of pregnancy will offer in the future further possibilities in early diagnosis, prediction, and monitoring pregnancy diseases.  相似文献   
92.
Periodontitis or Periodontal disease(PD) and Rheumatoid arthritis(RA) are two the most common chronic inflammatory diseases. Periodontitis is a biofilm associated destructive inflammatory disease of the periodontium caused by specific microorganisms. Rheumatoid arthritis is an autoimmune condition and is identified by elevated serum autoantibody titre directed against citrullinated peptides or rheumatoid factor. Periodontitis may involve some elements of autoimmunity. Recent studies have established that PD and RA show a common pathway and could be closely associated through a common dysregulation and dysfunction in inflammatory mechanism. The enzyme peptidyl arginine deiminase(PAD), expressed by Porphyromonas gingivalis(P. gingivalis) is responsible for the enzymatic deimination of arginine residuals to citrulline resulting in protein citrullination and its increased accumulation in RA.Citrullination by PAD may act as a putative biologic link between PD and RA. Association of Human leukocytic antigen-DR4 antigen has been established both with RA and PD. Several interleukins and inflammatory mediators(ILs) and Nuclear factor kappa beta ligand are linked to these common chronic inflammatory diseases. Antibodies directed against heat shock protein(hsp 70 ab) of P. gingivalis, P. melanogenicus and P. intermedia are raised in PD as well as RA. Both the conditions share many pathological and immunological similarities. Bacterial infection, genetic susceptibility, altered immune reaction and inflammatory mediators considered responsible for RA are also associated with PD. So it is plausible that a biological link may exist between PD and RA. Therapies aimed at modifying the expression and effect of inflammatory mediators and effector molecules such as matrix metalloproteinases, proinflammatory cytokines and autoantibodies of structural proteins may probably reduce the severity of both RA and PD.  相似文献   
93.
94.
Allopregnanolone is a neuroactive steroid present in the brain, but also measurable in systemic circulation. It exhibits anxiolytic and anticonvulsant effects and is able to produce hyperphagia. Since eating behavior disturbances and increased peripheral basal sympathetic activity have been reported in obese subjects, the present study investigated allopregnanolone and catecholamine (epinephrine and norepinephrine) responses to corticotropin-releasing hormone (CRH) in obese subjects. Blood was sampled from 39 obese (14 men and 25 women) and 57 normal-weight subjects (20 men and 37 women) and assayed for cortisol, allopregnanolone and catecholamines concentrations. In addition, 13 obese patients (5 men and 8 women) and 18 control subjects (9 men and 9 women) were submitted to a CRH test. Plasma allopregnanolone and norepinephrine levels were significantly higher in obese than in control subjects (p < 0.01), but plasma cortisol and epinephrine concentrations were comparable in both groups. No correlation was found in any group between plasma allopregnanolone and norepinephrine or epinephrine levels. Acute CRH administration significantly stimulated allopregnanolone secretion, with peak levels at 15 min in obese subjects, whereas maximal concentrations were reached after 60 min only in controls. In obese patients the allopregnanolone secretory incremental area was significantly higher than in controls (p < 0.02). CRH injection increased cortisol levels to a comparable extent in both groups. Plasma norepinephrine or epinephrine levels did were not significantly affected by CRH test in either group. In conclusion, obese subjects present higher allopregnanolone levels and a greater response to CRH than normal subjects. Since allopregnanolone has hyperphagic effects in rats, hypersecretion of the hormone in obese patients may represent one of the mechanisms underlying obesity.  相似文献   
95.
BACKGROUND: Aim of this study is to estimate the effectiveness of epidural electric stimulation of spinal cord for the treatment of patients with severe peripheral chronic arteriopathy who can't be surgically treated or when surgical therapy failed. METHODS: A retrospective study was carried out on 18 patients with peripheral chronic arteriopathy at clinical stage I of Fontaine classification; average age was of 60.08 years an they had rest pain and dystrophic lesions. Five patients couldn't be surgically treated. Stimulator catheter was placed in the epidural space and its action was evaluated studying lesion demarcation and pain resolution. RESULTS: In 16 cases there was a good pain control and in 14 patients lesion demarcation, while in 4 cases there was cases no improvement and amputation was necessary. CONCLUSIONS: Epidural electric stimulation of spinal cord is a valid treatment in selected patients for ischemia pain control and limb savage.  相似文献   
96.
97.
BB-10010 is a genetically engineered variant of human macrophage inflammatory protein-1 alpha with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of BB-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S12, and progenitors with marrow repopulating ability (MRA). A single subcutaneous dose of BB-10010 caused a twofold increase in circulating numbers of CFU-S8, CFU-S12, and MRA 30 minutes after dosing. We also investigated the effects of granulocyte colony-stimulating factor (G- CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-10010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA even further to 38-, 33-, and 100- fold. Splenectomy resulted in increased circulating progenitor numbers but did not change the pattern of mobilization. Two days of treatment with G-CSF then increased circulating CFU-S8, CFU-S12, and MRA by 64-, 69-, and 32-fold. A single BB-10010 administration after G-CSF treatment further increased them to 85-, 117-, and 140-fold, respectively, compared with control. We conclude that BB-10010 causes a rapid increase in the number of circulating hematopoietic progenitors and further enhances the numbers induced by pretreatment with G-CSF. BB- 10010 preferentially mobilized the more primitive progenitors with marrow repopulating activity, releasing four times the number achieved with G-CSF alone. Translated into a clinical setting, this improvement in progenitor cell mobilization may enhance the efficiency of harvest and the quality of grafts for peripheral blood stem cell transplantation.  相似文献   
98.
BACKGROUND & AIMS: Nutrients and properties of lipases affect survival of lipolytic activity during aboral gastrointestinal transit. Whether different doses and formulations of bacterial lipase and diets affect steatorrhea was tested in pancreatic-insufficient dogs. METHODS: A dose of 0-600,000 IU of powdered and 135,000 and 300,000 IU of liquid bacterial lipase was given with a standard meal to 5 dogs with ligated pancreatic ducts. In 4 dogs, 0 or 300,000 IU (normal 6-hour postprandial amount) of powder bacterial lipase was also given with five meals containing 850 kcal with different nutrient caloric densities (mixture design). Coefficients of fat absorption during 72- hour fecal balance studies were used to assess treatments. RESULTS: With the standard meal, powder bacterial lipase reduced steatorrhea in a dose-dependent manner (P = 0.03), and 135,000 and 300,000 IU of the liquid form decreased steatorrhea more than powder bacterial lipase (P = 0.017 and 0.057, respectively). Coefficients of fat absorption with 300,000 IU of powder bacterial lipase correlated (r2 = 0.79; P < 0.001) with increasing proportions of fat calories in diets. CONCLUSIONS: Liquid bacterial lipase decreases steatorrhea more than powder, and 300,000 IU of powder bacterial lipase ingested with high-fat meals corrects canine pancreatic steatorrhea. The combination of adequate mixing of small amounts (milligrams) of bacterial lipase and high-fat meals abolishes canine steatorrhea and may abolish human pancreatic steatorrhea. (Gastroenterology 1997 Jun;112(6):2048-55)  相似文献   
99.
100.
BACKGROUND: Hepatitis G virus (HGV) is a blood-borne flavivirus that may cause acute and chronic transfusion-transmitted infections. Patients with complement component 1 (C1) inhibitor (C1-INH) deficiency may acquire blood-borne infections through infusion of plasma concentrates. STUDY DESIGN AND METHODS: Serum samples from 84 patients with C1-INH deficiency (19 who received unmodified C1-INH concentrates, 23 who received steam-heated concentrates, and 42 untreated patients) were tested for HGV RNA and hepatitis C virus (HCV) RNA by a nested polymerase chain reaction (PCR). The samples were also tested for antibodies to the E2 envelope protein of HGV (anti-HGV) and to HCV with enzyme-linked immunosorbent assays. RESULTS: Nine (11%) patients had serum HGV RNA; that is, 7 (17%) of 42 patients previously treated with C1-INH concentrates and 2 of 42 previously untreated patients. HGV RNA was as common in the 19 patients treated with unmodified concentrates as in the 23 given steam-heated concentrates (16 vs. 17%, p = 0.60). Anti-HGV was more common among the recipients of unmodified concentrates than among those given steam-heated concentrates (26 vs. 0%, p = 0.014). HCV RNA was more frequently detected in treated patients than in untreated patients (33 vs. 7%, p = 0.005) and in the 19 recipients of unmodified concentrates than in the 23 treated with steam-heated concentrates (58 vs. 16%, p = 0.003). Only one HGV RNA- seropositive patient had elevated serum aminotransferase activity, compared to 11 with HCV RNA. CONCLUSION: HGV was transmitted by both unmodified and steam-heated concentrates, but it caused persistent viremia in a minority of the cases and was rarely associated with liver disease.  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