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   14915篇
  免费   815篇
  国内免费   64篇
耳鼻咽喉   291篇
儿科学   400篇
妇产科学   473篇
基础医学   2069篇
口腔科学   1110篇
临床医学   909篇
内科学   3313篇
皮肤病学   521篇
神经病学   1324篇
特种医学   415篇
外科学   2283篇
综合类   55篇
一般理论   3篇
预防医学   930篇
眼科学   202篇
药学   774篇
中国医学   76篇
肿瘤学   646篇
  2023年   101篇
  2022年   211篇
  2021年   523篇
  2020年   358篇
  2019年   430篇
  2018年   514篇
  2017年   364篇
  2016年   374篇
  2015年   482篇
  2014年   659篇
  2013年   755篇
  2012年   1171篇
  2011年   1250篇
  2010年   760篇
  2009年   634篇
  2008年   1060篇
  2007年   1033篇
  2006年   994篇
  2005年   964篇
  2004年   743篇
  2003年   658篇
  2002年   590篇
  2001年   80篇
  2000年   59篇
  1999年   89篇
  1998年   103篇
  1997年   112篇
  1996年   82篇
  1995年   83篇
  1994年   58篇
  1993年   61篇
  1992年   40篇
  1991年   43篇
  1990年   33篇
  1989年   23篇
  1988年   31篇
  1987年   23篇
  1986年   21篇
  1985年   12篇
  1984年   22篇
  1983年   20篇
  1982年   20篇
  1981年   20篇
  1980年   14篇
  1979年   10篇
  1978年   9篇
  1977年   10篇
  1976年   9篇
  1975年   15篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
We studied neuromuscular transmission in 16 patients with prior poliomyelitis by measuring single fiber electromyographic (SFEMG) jitter. This was compared with 3 indirect methods of assessing reinnervation: SFEMG fiber density, macro EMG, and the presence of fiber type grouping on muscle biopsy. In patients with acute poliomyelitis before the age of 10, there was a positive correlation between the extent of neuromuscular transmission impairment, demonstrated by increased SFEMG jitter, and the enlargement of the motor unit, as indicated by increased fiber density, increased macro EMG signals, and fiber type grouping on muscle biopsy. However, there was no correlation between any of these parameters and the presence or absence of new symptoms of weakness. These findings suggest that impaired neuromuscular transmission is most common in patients with prior poliomyelitis whose motor units have been maximally enlarged by axonal sprouting, but is independent of the presence or absence of new symptoms of weakness.  相似文献   
44.
Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP. Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA) analysis were performed upon clinical data, distribution of interictal spikes, and ictal chronology of seizures. From MVA, a final predictive model (FPM) was determined to better predict TPP and APP. Forty patients showed TPP (78.5%) and 11 patients APP (21.5%). Accuracy of ictal SPECT was higher in the unilateral (UIS) than in the bilateral (BIS) interictal spikes group (P = 0.05). FPM showed that patients exhibiting BIS, with shorter proportion of the electrographic seizure occurring after completion of tracer injection, and longer clinical than EEG seizure duration had more APP (P = 0.003). Generalized tonic-clonic seizures did not result in more APP. We concluded that analysis of ictal SPECT in TLE requires the knowledge of TPP and APP, the distribution of interictal spikes on temporal lobes and the ictal chronology of seizures. BIS showed that beyond a more complex epileptogenicity and seizure propagation, they may also lead to APP.  相似文献   
45.
46.
Sinotubular junction reconstruction in reimplantation type of valve-sparing aortic procedure can present some problem when a Valsalva graft is used. Since in the Valsalva graft the sinotubular junction height is predetermined, correct matching with native commissures height can be difficult. We propose a method by which it is possible to create a new sinotubular junction in Valsalva graft without altering its original configuration.  相似文献   
47.
This research was carried out to determine a potential role of leukotrienes in the acute hepatotoxicity induced by CC14 in rats. An inhibitor of leukotrienes biosynthesis, diethylcarbamazine (DEC, 25 and 50 mg ·kg-1 ip) exerted hepatoprotective effects, decreasing the activity of alanine aminotransfer-ase in serum and the concentration of liver triglycerides. DEC reduced histological damage of liver evidenced by electron microscopy. The hepatoprotective effects of DEC were dose-dependent. The results favor the role of leukotrienes in CC14 hepatotoxicity.  相似文献   
48.
49.
With a mean follow-up of 3 (1-6) years, we report on 21 patients who underwent multiple level cervical fusion, using autologous iliac crest grafts. Dis-cectomies were performed in 14 patients and cor-pectomies in another 7. Instrumentation was used in all patients with colectomies and in 2 patients who underwent 2-level and 3-level discectomies. Non-union occurred in 1 patient at 1 level. Graft displacement requiring reoperation was observed in 2 patients with massive corpectomies, in 1 of them as a consequence of trauma. In both patients complete bony fusion was obtained after reoperation and no other complications were observed. We conclude that the success rate with multiple-level fusion is comparable to that of single-level fusion when adequate fixation is achieved.  相似文献   
50.
BACKGROUND/AIMS: Hepatocytes (HEP) have been the major target for structural quantification in the liver, but an estimation of their total number (N), their percentage in relation to the global number of liver cells and the evaluation of the percentage of binucleated hepatocytes (BnHEPs) have never been performed with modern design-based stereological techniques. The establishment of sound technical guidelines and baseline quantitative data in non-pathological conditions are relevant to properly evaluate HEP hyperplasia and BnHEP responses. METHODS: In this study, we combined immunocytochemistry with sound design-based stereology for estimating the N of HEP and the N of non-hepatocytic cells (NHCs). For obtaining systematic uniform random sections (30 microm thick), a smooth fractionator sampling scheme was applied to the liver of five male Wistar rats (3 month old). Those sections were immunostained with polyclonal antibodies against carcinoembryonic antigen. Because biliary canaliculi were then marked, an unequivocal counting of mononucleated hepatocytes (MnHEP) and BnHEP was allowed. RESULTS: The N of HEP was estimated to be 1.93 x 10(9), with a coefficient of error (CE) of 0.02, corresponding to 129 x 10(6) HEP/g of liver. BnHEP represented 26% of total HEP number. The N of NHC was estimated as 1.31 x 10(9) (CE=0.02). CONCLUSION: The strategy here presented provides a reliable method for accessing the N of HEP (distinguishing MnHEP from BnHEP) in situations in which these parameters are relevant, namely for evaluating the magnitude of an hyperplastic liver response from its very early onset.  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