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   2081篇
  免费   146篇
  国内免费   9篇
耳鼻咽喉   11篇
儿科学   44篇
妇产科学   26篇
基础医学   317篇
口腔科学   35篇
临床医学   246篇
内科学   439篇
皮肤病学   21篇
神经病学   161篇
特种医学   127篇
外科学   260篇
综合类   21篇
一般理论   6篇
预防医学   186篇
眼科学   47篇
药学   117篇
肿瘤学   172篇
  2023年   19篇
  2022年   20篇
  2021年   37篇
  2020年   48篇
  2019年   56篇
  2018年   56篇
  2017年   53篇
  2016年   56篇
  2015年   54篇
  2014年   88篇
  2013年   116篇
  2012年   144篇
  2011年   153篇
  2010年   78篇
  2009年   80篇
  2008年   127篇
  2007年   125篇
  2006年   123篇
  2005年   139篇
  2004年   102篇
  2003年   81篇
  2002年   100篇
  2001年   20篇
  2000年   17篇
  1999年   15篇
  1998年   16篇
  1997年   10篇
  1996年   23篇
  1995年   16篇
  1994年   12篇
  1993年   13篇
  1992年   11篇
  1991年   16篇
  1990年   12篇
  1989年   12篇
  1988年   13篇
  1987年   12篇
  1986年   10篇
  1985年   11篇
  1984年   18篇
  1983年   21篇
  1982年   8篇
  1979年   5篇
  1976年   5篇
  1975年   5篇
  1973年   7篇
  1972年   14篇
  1970年   6篇
  1967年   4篇
  1937年   4篇
排序方式: 共有2236条查询结果,搜索用时 15 毫秒
1.
We thank Geluk and Zijlstra for their kind words as well astheir considerations and proposals. The latter hits right intothe heart of the issue: should one stick to the ‘anatomic’paradigm urging us to detect and treat coronary stenoses andcalcifications rather than follow  相似文献   
2.
In a prospective, randomized trial, 104 consecutive patients with displaced femoral neck fractures were allocated either to fixation with a sliding screw plate or 4 ASIF cancellous bone screws. The patients were reexamined at fixed intervals to determine the time of union. The 2-year-cumulated rate of union was 64 per cent in the plate group and 84 per cent in the screw group.  相似文献   
3.
Summary One hundred thirty-one breast carcinomas with medullary features, registered in the Danish Breast Cancer Cooperative Group from 1977–1982, have been histopathologically reviewed by two senior pathologists and classified as typical medullary carcinoma (TMC), atypical medullary carcinoma (AMC), and non-medullary carcinoma (NMC). Diagnostic criteria were based on those put forward by Ridolfiet al. and Fisheret al. The procedure was repeated with an interval of about one year by both pathologists. The diagnostic interobserver agreement was 72% with a Kappa of 0.55. The intraobserver agreement was 77% and 63% with Kappa values of 0.64 and 0.44, respectively. To see whether the observed inter- and intraobserver variability had any prognostic implications, diagnostic subgroups for both pathologists were analyzed with Kaplan Meier plots for recurrence-free survival (RFS) and with log rank tests. In the first evaluation pathologist 1 segregated a group of TMC with a significantly better RFS than for the NMC group, and pathologist 2 segregated a group of TMC with a corresponding strong trend. These findings could not, however, be reproduced in the second evaluation. The study indicates that the criteria of TMC and AMC as proposed by Ridolfiet al. need to be sharpened and simplified in order to reduce inter-and intraobserver variability. Larger studies with a control group of infiltrating ductal carcinomas are mandatory to elucidate the clinical importance of the diagnoses of Typical and Atypical Medullary Carcinoma of the breast.  相似文献   
4.
5.
This paper investigates the association between individually measured socioeconomic status (SES) and all-cause survival in colorectal cancer patients, and explores whether factors related to the patient, the disease, or the surgical treatment mediate the observed social gradient.  相似文献   
6.
In this ongoing study, patients with an estimated prostate size of no more than 20 gm are randomized to undergo either transurethral resection of the prostate (TURP) or transurethral incision (TUIP) at the 6 o'clock position. To date, 93 patients have been included, and 3 months postoperatively, 80 to 90 per cent of the patients in each group reported improvement. There was also a significant decrease in symptom scores and a significant increase in maximum urinary flow rate, with great variation within each group but without difference between the groups. In both groups, there appears to be some deterioration over time. Operating time, estimated blood loss, time to catheter removal postoperatively, and duration of postoperative hospital stay were all significantly in favor of TUIP. Loss of ejaculation was reported by 37 per cent of patients after TURP and by 13 per cent after TUIP (not statistically significant). There was no difference between the groups in the need for further surgery. Therefore, TUIP is recommended as an alternative to TURP in patients with small prostates.  相似文献   
7.
Lower tract localisation studies have been the gold standard in diagnosing various kinds of prostatitis. Four clinical categories are recognised: acute and chronic bacterial prostatitis, nonbacterial prostatitis, and prostatodynia. In acute bacterial prostatitis Gram-negative bacteria are the most common pathogens isolated. The roles of Gram-positive bacteria in chronic bacterial prostatitis and of Chlamydia trachomatis in nonbacterial prostatitis are contentious. Treatment of these various forms of prostatitis has been a challenge to the clinician. The lack of penetration of various drugs into the prostatic tissue, because of poor lipid solubility, ionisation, protein binding, and unfavourable pH gradients from the plasma to the prostatic fluid, may be the main reasons for poor results. The minimum inhibitory concentration (MIC) of antibacterial drugs used, and the concentration of drugs actually obtained in the prostate, combined with the influence of pH and inoculum size, and the effect of prostatic fluid and prostatic extracts on MIC are important factors in determining at least the theoretical efficacy of various drugs in the treatment of prostatitis. The new fluoroquinolone ofloxacin, the first quinolone to be approved for the treatment of chronic bacterial prostatis, has excellent penetration into human prostate and high in vitro activity in human urine and prostatic tissue. From a theoretical standpoint, ofloxacin should be ideal in the treatment of chronic bacterial prostatis. Comparative studies have shown its superiority to carbenicillin. Several noncomparative studies have also been reported. The initial results are promising, but further investigations are needed.  相似文献   
8.
9.
We have used the patch-clamp technique to characterize three anion channels in the ventricular membrane of the choroid plexus epithelium from Necturus. The most frequently occurring channel had a nonlinear IV-curve. The conductance in excised patches with 112 mM chloride at both sides was 28 pS at 0 mV, increasing towards positive membrane potentials. The selectivity ratios were P NaP Cl 0.1 and . SITS and furosemide (1 mM) on the inside reduces chloride flux to 0.15 and 0.37 times the control value. In attached patches, the most commonly observed channel had a conductance of 7.5 pS. The single-channel current for this channel reversed direction at 15 mV hyperpolarization, indicating accumulation of chloride to a factor of 1.8 above equilibrium. External stimulation of the tissue by theophylline, IBMX and dbcAMP, or by hypotonic shock did not increase the activity of this channel. In very few excised patches, we have observed a chloride channel with a conductance of 7 pS with 112 mM chloride at both sides. The 7 pS channel appears to be identical to a 2 pS channel found in attached patches. The 2 pS channel was not normally active in attached patches but was activated in 28% of the patches by external stimulation. Finally, in few excised patches we have found a 375 pS channel which inactivates within seconds when membrane potential is stepped from 0 mV to a value that differs more than 10–20 mV from zero. The channel did not conduct gluconate but and P NaP Cl 0.1. Internal SITS and furosemide (1 mM) reduced chloride flux to 0.3 and 0.5 times the control value. The channel was never seen in attached patches. The current carried through these channels can not account for the transepithelial steady state Cl-flux measured by microelectrodes. KCl exit from the cell is suggested to be carried by KCl-cotransport or by channels that are too small to be seen in patch-clamp experiments.  相似文献   
10.
Elderly people (age 75 years; n=48 males and 34 females) were studied in order to elucidate gender differences in elderly subjects on the determinants of muscle power (force and velocity) during a stretch-shortening cycle. All subjects performed three maximal counter-movement vertical jumps using both legs, on a force platform (Kistler 9281 B). The eccentric (Ep) and concentric (Cp) phases of the jumps were analyzed. The Ep was further divided into an acceleration phase (Epacc: from the start of the downward movement to the maximal negative velocity) and deceleration phase (Epdec: from the maximal negative velocity to the end of the downward movement). Jump height for the men was higher than for the women (P < 0.001). During both Epacc and Epdec no significant differences were observed between males and females in force and power generation. However, the men had a higher peak muscle power during the Cp, which may be explained exclusively by the velocity determinant (P < 0.001). No specific gender-related strategy appeared to influence the motor pattern of the movement. The comparable eccentric force generation of the leg extensors in both genders suggests a similar ability to cope with eccentric muscle actions during everyday activities. In contrast, the marked lower capacity for concentric contractions in women may result in an impaired performance, especially in activities where intense and rapid movements are essential, for example when reversing a forward fall. This may be one reason why elderly women are more prone to falls than are elderly men. Accepted: 19 September 2000  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