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   9770篇
  免费   543篇
  国内免费   40篇
耳鼻咽喉   40篇
儿科学   178篇
妇产科学   182篇
基础医学   1306篇
口腔科学   445篇
临床医学   814篇
内科学   2652篇
皮肤病学   255篇
神经病学   994篇
特种医学   297篇
外科学   1168篇
综合类   26篇
一般理论   2篇
预防医学   457篇
眼科学   131篇
药学   559篇
中国医学   27篇
肿瘤学   820篇
  2024年   8篇
  2023年   72篇
  2022年   153篇
  2021年   290篇
  2020年   158篇
  2019年   230篇
  2018年   273篇
  2017年   217篇
  2016年   223篇
  2015年   276篇
  2014年   384篇
  2013年   475篇
  2012年   767篇
  2011年   788篇
  2010年   409篇
  2009年   372篇
  2008年   654篇
  2007年   671篇
  2006年   592篇
  2005年   641篇
  2004年   553篇
  2003年   496篇
  2002年   477篇
  2001年   100篇
  2000年   87篇
  1999年   90篇
  1998年   107篇
  1997年   74篇
  1996年   73篇
  1995年   68篇
  1994年   57篇
  1993年   40篇
  1992年   48篇
  1991年   46篇
  1990年   47篇
  1989年   44篇
  1988年   30篇
  1987年   35篇
  1986年   34篇
  1985年   23篇
  1984年   23篇
  1983年   24篇
  1982年   18篇
  1981年   8篇
  1980年   18篇
  1979年   9篇
  1976年   9篇
  1974年   8篇
  1970年   6篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
  1. The role played by endogenous lipocortin 1 in the anti-migratory action exerted by dexamethasone (Dex) on monocyte recruitment in an in vivo model of acute inflammation was investigated by use of several neutralizing polyclonal antibodies raised against lipocortin 1 or a lipocortin 1-derived N-terminus peptide (peptide Ac2-26). The efficacy of peptide Ac2-26 in inhibiting monocyte and polymorphonuclear leucocyte (PMN) recruitment was also tested.
  2. Intraperitoneal (i.p.) injection of zymosan A (1 mg) produced a time-dependent cell accumulation into mouse peritoneal cavities which followed a typical profile of acute inflammation: PMN influx was maximal at 4 h post-zymosan (between 15 and 20×106 cells per mouse), and this was followed by an accumulation of monocytes which peaked at the 24 h time-point (between 10 and 15×106 cells per mouse).
  3. Dex administration to mice reduced zymosan-induced 4 h PMN infiltration and 24 h monocyte accumulation with similar efficacy: approximately 50% of inhibition of recruitment of both cell types was achieved at the dose of 30 μg per mouse (∼1 mg kg−1, subcutaneously (s.c.)). Maximal inhibitions of 64% and 67% on PMN and monocyte recruitment, respectively, were measured after a dose of 100 μg per mouse (∼3 mg kg−1, s.c.).
  4. Dex (30 μg s.c.) inhibited monocyte (53%) and PMN (69%) accumulation in response to zymosan application in mice which had been treated with a non-immune sheep serum (50 μl s.c.). In contrast, the steroid was no longer active in reducing cell accumulation in mice which had been passively immunized against full length human recombinant lipocortin 1 (serum LCS3), or against lipocortin 1 N-terminus peptide.
  5. Treatment of mice with vinblastine (1 mg kg−1, intravenously (i.v.)) produced a remarkable leucopenia as assessed 24 h after administration. This was accompanied by a 60% reduction in 4 h-PMN influx, and by a 27% reduction in 24 h-monocyte accumulation, measured after zymosan administration. The inhibitory effect of Dex on monocyte recruitment was not significantly modified in vinblastine-treated mice, with 36% and 57% of inhibition calculated at the dose of 30 μg Dex, and 70% and 60% of inhibition at 100 μg Dex, in vehicle- and vinblastine-treated mice, respectively.
  6. Treatment of mice with peptide Ac2-26 dose-dependently attenuated PMN influx at 4 h post-zymosan with a significant effect at 100 μg per mouse (45% of inhibition, n=9, P<0.05) and a maximal effect of 61% inhibition at the highest dose tested of 200 μg s.c. (n=14, P<0.05). No effect of peptide Ac2-26 (200 μg s.c.) was seen on zymosan-induced 24 h monocyte recruitment. In contrast, administration of 200 μg peptide Ac2-26 every 6 h was effective in reducing the number of monocytes harvested from the inflamed peritoneal cavities at 24 h post-zymosan: 9.40±0.58×106 monocytes per mouse (n=13) and 5.74±0.34 monocytes per mouse (n=14) in vehicle- and peptide Ac2-26-treated mice, respectively (P<0.05).
  7. Finally, peptide Ac2-26 produced a concentration-dependent inhibition of the rate of phagocytosis of mouse resident peritoneal macrophages as measured by flow cytometry, with a maximal reduction of 34% at the highest concentration tested of 100 μg ml−1 (n=8 experiments performed in duplicate; P<0.05).
  8. In conclusion, this study suggests that in vivo monocyte recruitment during acute inflammation is, at least in part, under the negative modulatory control of endogenous lipocortin 1 (as seen after administration of Dex by using the specific antisera) and exogenous lipocortin 1 mimetics (as observed with peptide Ac2-26). In addition to the neutrophil, we can now propose that the monocyte also can be a target for the in vivo anti-inflammatory action of lipocortin 1.
  相似文献   
42.
43.
Rolipram is a type IV phosphodiesterase inhibitor endowed with powerful immunomodulatory properties. In this study, we evaluated the effects of this drug on the development of the T-cell-mediated hepatitis inducible in mice by concanavalin A. The results indicated that prophylactic treatment with either 5 or 10 mg/kg rolipram injected intraperitoneally 24 h and 1 h prior to intravenous (i.v.) challenge with 20 mg/kg concanavalin A successfully ameliorated serological and histological signs of liver damage, so that the treated mice showed lower transaminase levels in the plasma and milder mononuclear cell infiltration of the liver as compared to vehicle-treated controls. Moreover, this effect was associated with profound modifications of circulating levels of cytokines released after concanavalin A injection, with the blood levels of interferon-gamma and tumor necrosis factor-alpha being significantly lower and those of interleukin-10 higher than those of the control mice. In particular, the increased blood levels of interleukin-10 might play an important role in the anti-hepatitic effects of rolipram as coadministering this compound with anti-interleukin-10 monoclonal antibody significantly reduced its anti-inflammatory action. These results suggest that rolipram may be useful in the clinical setting for the treatment of cell-mediated immunoinflammatory diseases such as immunoinflammatory hepatitis.  相似文献   
44.
Summary Experimental cerebral tumors have been induced by transplacental ENU. The morphologic study of the brains of treated rats revealed that cellular hyperplasias appear at the 30th day of extrauterine life in the paraventricular white matter, i.e., before the already known early neoplastic proliferations. Cytofluorimetric investigations failed to demonstrate differences between treated and control rats during the 1st month. On the contrary, adenylate cyclase activity is very high in that period. The duration of the latency period is discussed.This research was supported by Grants No. 79.00678.96 and No. 79.00664.96 of Progetto Finalizzato Control of Neoplastic Growth, Consiglio Nazionale delle Ricerche (C.N.R.), Rome  相似文献   
45.
It has been well established that Lonidamine (LND), [1,(2,4 dichlorobenzyl)-1H-indazol-3-carboxylic acid], affects tumor growth and enhances the effect of X-ray both in vitro and in vivo. Nevertheless, difficulties arise if the available experimental data should be utilized to design clinical trials since schedules, routes of administration as well as dosages greatly differ from those currently employed in the clinic. With the aim to overcome these difficulties, experiments with modalities similar to those employed in the current clinical practice have been undertaken to evaluate: (i) the influence of the LND dosage on the antitumor effect; (ii) the time lenght of its administration for the optimal effect; (iii) the best schedule of treatment when LND is associated with radiations. The results may be summarized as follows: (i) antitumor effectiveness of LND, in terms of growth delay, increases with LND dosage. Moreover, the drug administered from the day of transplant significantly decreases the tumor takes. (ii) to exert the antineoplastic effect LND must be administered continuosly because if the treatment is interrupted the tumor regrows like an untreated one. (iii) the maximal response of the association X-ray-LND is elicited when the drug is given after irradiation treatment.  相似文献   
46.
In our Institute we have performed 124 vertical banded gastroplasties. Patients with a follow-up beyond 3 months were studied with a barium meal, in order to evaluate the efficiency of surgery and the eventual complications. Seventy-nine patients have had one or more X-ray investigations at various times after surgery (for a total of 136 studies). The first 20 patients were routinely studied at 1, 2 and 3 years after the operation; the next 32 patients were studied for features such as vomiting, poor weight loss or low food intake; the last 27 patients were studied with an early overlook beginning 3 months after surgery. We noted gastroesophageal reflux in eight (10.1%) cases, outlet dilatation in four (5%) cases, outlet substenosis (diameter 6-8 mm) in 13 (16.4%) cases, outlet stenosis (diameter ≤5 mm) in four (5%) cases, peanut-type deformation in three (3.7%) cases, and staple-line disruption in 17 (21.5%) cases. The staple-line disruption was correlated in the first part of the series with a reinforcement of such a suture, while the last 27 patients, with vertical stapling carried out with a 4-row stapler without reinforcement, did not present any disruption. The radiographic examination gives information about weight loss and side effects.  相似文献   
47.
BACKGROUND: Aim of the study: to compare AG versus MAC using propofol & remifentanil in a day surgery setting evaluating intra and postoperative clinical conditions and emergence times. METHODS: Propofol and remifentanil, either for general anesthesia (AG) then conscious sedation (MAC), have been administered to 218 patients undergoing mainly plastic or proctologic surgery as day hospital. AG was induced with propofol 1.5-2 mg/kg followed by a continuous infusion of 10 mg/kg/h and remifentanil infused at 10 micrograms/kg/h; MAC was started with propofol 3 mg/kg/h and remifentanil 4-5 micrograms/kg/h; during the maintenance phase of both AG and MAC, infusion rates of both drugs were adjusted according to clinical needs. Diazepam (0.05-0.06 mg/kg) and/or midazolam (2-3 mg) were given as premedication or coinduction as necessary. All patients received field infiltration with local anesthetics (lidocaine or mepivacaine); patients under GA were artificially ventilated with O2/air through IOT or LMA. Surgical and anesthesiological data were collected on specially designed records, with special attention to time intervals between anesthesia (FA) and surgery (FC) end and eyes opening (EO), orientation (OR), return of spontaneous breathing (SR), extubation (EST), sitting (SED), walking (CAMM), dressing (VEST) and discharge (DIM); data were analyzed with parametric and non parametric analysis of variance. RESULTS: All emergence intervals were longer under AG than under MAC: the earlier in the range of 4-5 vs 0.5-1 min; for the late intervals; FA-SED 24 +/- 18 vs 15 +/- 8, FA-PIED 65 +/- 48 vs 34 +/- 17, FA-VEST 69 +/- 58 vs 33 +/- 17, FA-CAMM 68 +/- 42 vs 39 +/- 19. Discharge times (83 +/- 67 vs 73 +/- 60) were similar between the two groups. Drugs consumption under AG were roughly double than under MAC; total dose infused of propofol (mg/kg/min) 0.118 +/- 0.044 vs 0.06 +/- 0.036; total dose of remifentanil (microgram/kg/min): 0.106 +/- 0.049 vs 0.066 +/- 0.027. AG resulted in a higher % incidence of intraoperative hypotension and bradycardia: hypotension 61.7 vs 25.7 and bradycardia 30.3 vs 12.4. SaO2 decreased more commonly during MAC than AG (20.9% vs 10.1); intraoperative itching was referred in 20% of MAC patients. Conversions rate from MAC to AG was 2.8%. Psychomotor agitation was more frequent following AG (14%) than MAC (2%); nausea (1%), vomiting, shivering (12%), headache (2%), ortostatic hypotension (2%) were similar between the two groups. Diazepam and/or midazolam caused a significant prolongation of recovery intervals, for both AG and MAC with a mean delay of the order of 100-200%. CONCLUSIONS: Propofol- remifentanil gave excellent conditions for a wide variety of day surgery procedures, offering good anesthesia with quick emergence; the addition of bdz, even at low doses, prolongs significantly discharge times.  相似文献   
48.
It is currently accepted that vinil infections may influence the development of atopy. In the present study we evaluated serum IgE levels as well as the prevalence of symptom-, indicative of utopic disease and EBV antibodies in 353 children aged from I month to 19 years. Antibodies against EBV were detected by immunofluorescence. IgE levels in serum were measured by en/. yme imimmoassay. Dividing ihe study population according to EBV seropositivity and age, we noted that the prevalence of high IgE levels (> 2 s. d.) was, in total, more frequent in the EBV negative (32. 9%) than in the positive subjects (27. 6%). Interestingly, this higher prevalence was found only in the groups aged under six, especially in the 7 to 29 month group, where it was statistically significant (p=0.037), whereas in the 6-19 year group the situation was reversed. Furthermore, selecting only the atopic children younger than 3 years of age with high IgE levels and clinical symptoms of atopy (wheezing and/or dermatitis) it was possible to demonstrate lower EBV seropositivity compared with the normal IgE controls for each group, even though these differences were not statistically significant. In conclusion, the results of our study suggest that, in our selected population, EBV infection in the first years of life is associated with a lower prevalence of high IgE levels.  相似文献   
49.
Objective To estimate the risk of specific adverse neonatal events resulting from the combined effects of prematurity and low birthweight in very preterm infants (delivered at 24–31 weeks of gestation)
Design A cohort study of specific adverse neonatal events in preterm infants born at between 24 and 31 weeks of gestation.
Setting Pavia, Italy.
Population Two hundred and thirty singleton infants with sonographically confirmed gestational age, delivered at 24 to 31 weeks of gestation.
Methods To evaluate the impact of a lower than expected birthweight on selected neonatal events independently of gestational age, we calculated birthweight standard deviation scores (differences between actual birthweight and fitted birthweight divided by fitted standard deviation) for each week of gestation.
Results After adjustment for gestational age and other confounders, there was a significant linear trend relating a decreasing birthweight SDS to an increased likelihood of neonatal death, intraventricular haemorrhage, severe respiratory distress syndrome, and acidosis. Compared with infants with SDS 0 ( 50th centile of birthweight), infants with birthweight SDS < −1 (< 16th centile) had increased odds for neonatal death [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.42–9.6], grade III-IV intraventricular haemorrhage (OR 17.5, 95% CI 4.04–75.9), and neonatal acidosis (OR 3.22, 95% CI 1.41–7.4). The significance of birthweight SDS as a predictor of neonatal outcome, however, was lower than that of gestational age.
Conclusions A lower than expected birthweight affects the likelihood of several adverse neonatal events in very preterm infants. However, a decreasing birthweight SDS affects neonatal outcome less than decreasing gestation does.  相似文献   
50.
We report the case of a young girl with recurrent sharp pain in the outer aspect of the ankle. She had no previous trauma. High-resolution US (HRUS) showed a complete intermittent dislocation of the peroneal tendons. Post-traumatic chronic peroneal instability is quite common, whereas complete dislocation is rare. HRUS is an important adjunct to clinical examination and radiographic evaluation of patients with musculoskeletal disorders of the foot and ankle [1]. This paper reports its value in non-traumatic recurrent dislocation of the peroneal tendons. Received: 23 May 1997 Accepted: 1 December 1997  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