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   4525篇
  免费   295篇
  国内免费   26篇
耳鼻咽喉   148篇
儿科学   102篇
妇产科学   36篇
基础医学   619篇
口腔科学   105篇
临床医学   311篇
内科学   1179篇
皮肤病学   76篇
神经病学   488篇
特种医学   122篇
外科学   719篇
综合类   22篇
预防医学   132篇
眼科学   73篇
药学   303篇
中国医学   8篇
肿瘤学   403篇
  2023年   44篇
  2022年   95篇
  2021年   175篇
  2020年   87篇
  2019年   109篇
  2018年   125篇
  2017年   93篇
  2016年   109篇
  2015年   101篇
  2014年   121篇
  2013年   144篇
  2012年   240篇
  2011年   253篇
  2010年   119篇
  2009年   117篇
  2008年   211篇
  2007年   203篇
  2006年   189篇
  2005年   156篇
  2004年   177篇
  2003年   182篇
  2002年   139篇
  2001年   146篇
  2000年   165篇
  1999年   143篇
  1998年   50篇
  1997年   37篇
  1996年   41篇
  1995年   28篇
  1994年   27篇
  1993年   28篇
  1992年   101篇
  1991年   73篇
  1990年   84篇
  1989年   105篇
  1988年   84篇
  1987年   71篇
  1986年   65篇
  1985年   60篇
  1984年   42篇
  1983年   29篇
  1982年   18篇
  1980年   19篇
  1979年   36篇
  1978年   20篇
  1977年   26篇
  1975年   15篇
  1974年   15篇
  1968年   14篇
  1966年   14篇
排序方式: 共有4846条查询结果,搜索用时 15 毫秒
101.
A 63-year-old woman complained of chest pain and was referred to hospital where she was found to have left pleural effusion and swelling, local heat and edema of the right lower leg. Initial pulmonary perfusion scintigraphy demonstrated multiple defects and pulmonary thromboembolism (PTE) was confirmed during the anticoagulant and thrombolytic therapy against thrombophlebitis. A Greenfield filter was inserted in the inferior vena cava to prevent recurrence of PTE from the thrombosis that was resistant to therapy. In-111-labeled platelet scintigraphy (platelet scintigraphy) showed abnormal uptake of platelets in the chest, femoral veins and abdomen, which suggested active thrombus formation in those regions, including the filter, and a risk of recurrent PTE. Therefore, the thrombolytic therapy was terminated and the anticoagulant therapy intensified. A computed tomography (CT) scan revealed thrombus at the filter, which was markedly decreased 1 month later on platelet scintigraphy. Pulmonary ventilation and perfusion scintigraphy revealed remarkable improvement of the PTE. In this case, platelet scintigraphy complemented CT in demonstrating the activity and localization of the thrombus and can be used to evaluate the risk of recurrence during thrombolytic therapy after insertion of a filter.  相似文献   
102.
The frequency of infection in recipients of allogeneic bone marrow transplants (BMT) who received oral new quinolones (NQ) was compared with that in BMT recipients who were given oral vancomycin/tobramycin (V/T). Between 1984 and 1997, our hospital treated 79 patients with V/T and 90 patients with NQ. Number of febrile days, duration of intravenous antibiotics administration, and frequency of documented infections were statistically the same for both groups. However, the frequency of grampositive bacterial infections, especially staphylococcal infections, was slightly higher in patients receiving NQ than in patients receiving V/T (p = 0.12). Of the patients who received NQ, those who underwent unrelated donor BMT procedures were generally febrile for slightly longer periods than those who underwent related donor BMT procedures (p = 0.10). These results suggest that oral NQ is as effective as oral V/T for the prevention of serious gramnegative bacterial infections in patients who undergo BMTs.  相似文献   
103.
A retrospective analysis of children with acute lymphoblastic leukemia (ALL) was performed to evaluate the current status of diagnosis and treatment of ALL in Japanese children. Clinical records of 670 children with ALL were collected and analyzed; these children had been diagnosed between 1991 and 1995 at the 53 institutions in 4 areas participating in the Japan Association of Childhood Leukemia Study. It was found that T-cell ALL was significantly less frequent in Tokai and Hokkaido than in Kansai and Chu-Shikoku. The overall induction rate was 92.4%. The estimated 7-year overall survival rate and event-free survival (EFS) rate were 76.0% +/- 1.9% and 61.4% +/- 2.1%, respectively. EFS rates were significantly different among the geographic areas. In female patients with B-cell precursor (B-pre) ALL and white blood cell counts at diagnosis (WBCsdiag) below 50.0 x 10(9)/L, favorable outcomes were significant. Favorable outcomes were not significant in B-pre ALL patients with a WBCdiag above 50.0 x 10(9)/L or in T-cell ALL patients. The EFS rate for infants was significantly worse than that for patients over 1 year of age. In B-pre ALL, but not in T-cell ALL, it was found that the higher the WBCdiag, the worse the EFS rate. Multivariate analysis showed that the following factors were significantly unfavorable for EFS: the Philadelphia chromosome, an translocations associated with chromosome 11q23, an acute unclassified leukemia, mixed-lineage leukemia, a WBCdiag above 100.0 x 10(9)/L, and male gender. Hyperdiploidy (> 50 chromosomes) was significantly favorable for EFS. For further tailoring of treatment and to improve the outcome in childhood ALL, a prospective large-scale study should be undertaken in Japan.  相似文献   
104.
BACKGROUND: Hepatitis C virus (HCV) viraemia is one of the factors for histological prognosis of chronic hepatitis C. METHODS: One hundred and thirty-five patients who received hepatic biopsies twice at intervals of 5 years or longer were followed up for a mean of 9.7 +/- 4.0 years were studied retrospectively. The amount of HCV viraemia present was measured as the concentration of HCV core protein by using the fluorescence enzyme immunoassay method. RESULTS: Multiple-regression analysis, using deterioration of the histological stage as a dependent variable, showed that greater age (P = 0.041), higher stage of hepatic histology at the start of follow up (P = 0.029), and higher serum concentration of core protein (P < 0.001) were independent factors affecting the deterioration of the liver's histological stage. At follow up, no significant difference in histological stage was seen between patients with serum HCV core protein > or = 100 pg/mL (n = 60) and those with serum core protein < 100 pg/mL (n = 75). The histological grade in patients with high serum core-protein levels tended to be significantly worse and the deterioration rate of the histological stage was significantly higher than in those with low HCV core protein levels (68 vs 35%, P < 0.001). The mutation rate of the HCV envelope-2/non-structural 1 (E2/NS1) nucleotide region was compared in two patients who had high serum concentrations of HCV core protein and whose histological stage had deteriorated with two patients who had low serum concentrations of the core protein and whose histological stages remained unchanged. No significant difference in E2/NS1 mutation was found. CONCLUSIONS: The amount of HCV viraemia was suggested to be a significant factor for determining histological outcome in patients with chronic hepatitis C. The mutation rate in the E2/NS1 region did not seem to be associated with the prognosis of chronic hepatitis C.  相似文献   
105.
Methyl bromide (MeBr) is used increasingly as a biocidal fumigant, primarily in agricultural soils prior to planting of crops. This usage carries potential for stratospheric ozone reduction due to Br atom catalysis, depending on how much MeBr escapes from fumigated soils to the atmosphere and on details of atmospheric chemical reactions. We present direct field measurements of MeBr escape; 87% of the applied MeBr was emitted within 7 days after a commercial fumigation. Covering the field with plastic sheets retarded MeBr escape somewhat but first-day losses were still 40%; thicker sections of sheets were relatively more effective than thin sections. We also measured gaseous MeBr concentrations versus depth in the soil column; these profiles display diffusion-like evolution. In soil, MeBr is partitioned among gas, liquid, and adsorbed solid phases. Calculated soil inventories agreed only roughly with applied amounts, probably due to nonequilibrium partitioning (during the first 30 min) and to uncertainties in partitioning coefficients. Fumigated fields may release less MeBr if they are covered by more gas-tight plastic films, if injection techniques are improved and injection is deeper, and if soil moistures, organic amounts, and densities are greater than in the soil studied here.  相似文献   
106.
Rats were given constant intravenous infusions of [3H]-leucine plus [1-14C]-2-ketoisocaproate (KIC). Specific activities of plasma leucine and plasma KIC reached plateaus by two to three hours. 3H specific activity of KIC was 85% +/- 2% of that in leucine. 14C specific activity of leucine was 36% +/- 2% of that in KIC. The 14C/3H ratios in leucine and KIC were constant from the earliest sampling time (one hour) at 0.65 +/- 0.03 and 2.20 +/- 0.07, respectively. In various tissues, 14C/3H in free leucine and in tissue protein were approximately equal, but in most organs these ratios were significantly greater than the ratio 14C/3H in plasma leucine. From these data we estimate that the fraction of leucine incorporated into protein in individual organs derived from extracellular KIC rather than extracellular leucine varies from zero (in liver and bone marrow) to 35% to 45% (in brain and heart), and comprises 12% in the body as a whole.  相似文献   
107.
The precise dynamic property of glucagon secretion in response to glucose concentration has not yet been elucidated, since in in vitro studies using pancreatic islets, the co-existence of pancreatic B cells modifies the mode of glucagon secretion, and in vivo studies, the exogenous insulin administration greatly affects pancreatic A cell function. In this study, to clarify the dynamic property of glucagon secretion in response to glucose concentration and the ability of glucagon to raise hepatic glucose production, an artificial endocrine pancreas was employed as a research tool. Our originally developed artificial endocrine pancreas prepared the glucagon and/or glucose infusion algorithm as the counterregulatory system. The principle of glucagon and glucose infusion algorithm is set as the proportional plus derivative modes of action to blood glucose concentration with time delay constant, as follows; Gn.I.R.(t) = Gp[BGp - BG(t - tau)] + Gd[-delta BG(t - tau)] + Gc G.I.R.(t) = Cp[BGp - BG(t - tau)] + Cd[-delta BG(t - tau)] where Gn.I.R.(t) and G.I.R.(t) are glucagon infusion rate and glucose infusion rate, respectively. BGp is the projected value of blood glucose concentration, and BG(t) and delta BG are blood glucose concentrations and the rate of change in blood glucose concentration at time t respectively. Gp and Gd are coefficients for glucagon infusion, and Cp and Cd are those for glucose infusion. Gc is the constant for basal glucagon supplementation. tau(min) is the time delay constant for glucagon and glucose infusion. In a depancreatized dog, the blood glucose concentration was maintained at the normoglycemic level with intraportal insulin infusion using this artificial endocrine pancreas for at least one hour, then hypoglycemia was induced by iv bolus insulin injection (0.1 U/kg). Glucagon was infused intraportally or glucose was infused into the peripheral vein when the counterregulatory system was operated according to each of these algorithm by variously changing the parameters. In the intraportal glucagon infusion algorithm, with the optimal parameters based on proportional plus derivative modes of action with a 10-min time delay (Gp/Gd/Gc/tau = 0.2/0.4/0.6/10), both the blood glucose response curves and plasma glucagon profiles simulated those seen in normal dogs. On the other hand, glucagon infusion based only on the proportional action failed to simulate the blood glucose response and plasma glucagon profile of normal dogs. When glucose was infused on the basis of the proportional action with a 20-min time delay (Cp/Cd/tau - 0.2/0/20), the insulin-induced hypoglycemia in depancreatized dogs could be restored to normoglycemia in the sa  相似文献   
108.
A 62-year-old woman admitted for rectal carcinoma suffered from a post-operative bacterial infection. Oxy-imino-beta-lactams including cefotiam (CTM) and cefozopran (CZOP) were prescribed for this case, but the patient developed a wound abscess followed by peritonitis. She recovered from the bacterial infection after drainage and recurrent washing of the abscess. An ephemeral aggravation of infectious signs was observed just after creation of an artificial anus, and CZOP was again administered, and no evident bacterial infection occurred. The patient recovered, then was followed as an outpatient to date. A CAZ-resistant (MIC, > 16 micrograms/ml) E. coli was recovered from pus of her wound abscess. Since the CAZ-resistance decreased (MIC, 64 micrograms/ml-->0.13 microgram/ml) by the presence of clavulanate (CVA) in this isolate, this strain was speculated to be an extended spectrum beta-lactamase (ESBL) producer at an early stage of infection. A similar strain was also isolated from the feces. Therefore, we immediately took measures to block the nosocomial spread of this microorganism, and we succeeded in preventing a nosocomial outbreak of this strain. It was later confirmed by PCR analysis and DNA sequencing analysis that this CAZ-resistant E. coli strain produces an ESBL (SHV-5-2a = SHV-12). This is the first report of a case of infection with SHV-derived ESBL producing E. coli strain in Japan. We are concerned that further dissemination of this kind of microorganism might occur in the near future also in Japan, as it has been widely observed in European countries and the US. We believe that it will be very important to distinguish the type of beta-lactamases for rigorous bacterial infection control with the prudent use of antibiotics. In other words, we in Japan must recall that various gram-negative bacterial species that produce TEM-, SHV-derived ESBLs, Toho-1, AmpC, or IMP-1 are already widespread. Thus, we should take this fact into consideration when we do antibiotic susceptibility tentings and interpretation of the results for promotion of accurate chemotherapy.  相似文献   
109.
An 80-year-old woman was admitted with cardiogenic shock; she arrived in a deep coma with systolic blood pressure of 44 mmHg. An electrocardiogram showed ST elevation in I, aVL, V5 and V6, suggesting myocardial infarction in the lateral area of the left ventricle. A chest roentgenogram showed right pulmonary edema without cardiomegaly. Transthoracic and transesophageal echocardiograms revealed severe mitral regurgitation and a flailing anterior mitral valve leaflet, suggesting a ruptured papillary muscle. The patient was initially treated with high-dose dopamine, dobutamine and norepinephrine. Intraaortic balloon pumping was initiated after the patient's condition stabilized. She underwent emergency mitral valve replacement with a prosthetic valve. Complete rupture of the anterior papillary muscle was confirmed. Histological examination revealed necrosis of the anterior papillary muscle with inflammatory changes. She recovered uneventfully. Postoperative coronary angiography demonstrated subtotal occlusion of the first diagonal branch, and left ventriculography demonstrated akinesis of the lateral segment. This was a rare case in which subtotal occlusion of the first diagonal branch caused rupture of an anterior papillary muscle leading to severe mitral regurgitation.  相似文献   
110.
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