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   7476篇
  免费   314篇
  国内免费   33篇
耳鼻咽喉   77篇
儿科学   158篇
妇产科学   132篇
基础医学   951篇
口腔科学   176篇
临床医学   477篇
内科学   1868篇
皮肤病学   153篇
神经病学   927篇
特种医学   201篇
外科学   1126篇
综合类   23篇
预防医学   191篇
眼科学   180篇
药学   419篇
中国医学   10篇
肿瘤学   754篇
  2022年   50篇
  2021年   127篇
  2020年   80篇
  2019年   116篇
  2018年   144篇
  2017年   98篇
  2016年   99篇
  2015年   123篇
  2014年   184篇
  2013年   223篇
  2012年   341篇
  2011年   353篇
  2010年   205篇
  2009年   160篇
  2008年   291篇
  2007年   341篇
  2006年   298篇
  2005年   351篇
  2004年   287篇
  2003年   317篇
  2002年   289篇
  2001年   216篇
  2000年   252篇
  1999年   197篇
  1998年   82篇
  1997年   69篇
  1996年   55篇
  1995年   71篇
  1994年   71篇
  1993年   49篇
  1992年   179篇
  1991年   175篇
  1990年   153篇
  1989年   174篇
  1988年   153篇
  1987年   127篇
  1986年   117篇
  1985年   131篇
  1984年   104篇
  1983年   87篇
  1979年   79篇
  1978年   53篇
  1977年   57篇
  1976年   49篇
  1974年   51篇
  1973年   58篇
  1972年   53篇
  1970年   55篇
  1969年   56篇
  1968年   45篇
排序方式: 共有7823条查询结果,搜索用时 31 毫秒
41.
42.
The aim of this study was to fabricate an artificial bile duct for the development of a new treatment for biliary diseases. Eighteen hybrid pigs were implanted with a bile duct organoid unit (BDOU) made of a bioabsorbable polymer. Twelve of the transplanted BDOUs had been seeded with autologous bone marrow cells (BMCs) in advance. Six animals, the controls, were grafted with the scaffold alone with no BMCs seeded. The common bile duct was cut, the hepatic cut end of the native common bile duct was anastomosed to the BDOU and the other end was anastomosed to the duodenum. The controls underwent a similar operation. The neo-bile duct was removed at pre-determined time points and investigated histologically. All 18 recipient pigs survived until their sacrifice at 6 weeks, 10 weeks or 6 months. Histological examination revealed incomplete epithelialization of the neo-bile duct at 6 weeks and 10 weeks after transplantation. At 6 months, the organoid exhibited a morphology almost identical to that of the native common bile duct. No differences were found between the controls and BMC-seeded pigs. These results show that the artificial bile duct thus fabricated can serve as a substitute for the native bile duct.  相似文献   
43.
In the present case, a patient in whom limb apraxia and asymmetrical parkinsonism developed suggesting corticobasal degeneration, is reported. Neuropathologic examination revealed numerous tufted astrocytes in the precentral cortex in addition to the characteristic pathologic findings of PSP. Therefore, on the basis of clinicopathologic features, atypical progressive supranuclear palsy was diagnosed. In addition, the brain tissue of the present patient was investigated with an antibody specific for four‐repeat tau (4R‐tau). In the precentral cortex, numerous tau‐positive tufted astrocytes, pretangles, and threads were positive for 4R‐tau. Using a confocal microscopy we demonstrated that tufted astrocytes positive for 4R‐tau were adjacent to astrocytes positive for GFAP. The present findings suggest that accumulation of four‐repeat tau in astrocytes is a degenerative process rather than a reactive process.  相似文献   
44.
An 8-month-old boy had an anterior type of persistent hyperplastic primary vitreous in the right eye. Results of needle biopsy, performed because of elevated intraocular pressure, disclosed clusters of blastic cells. The eye was enucleated on the suspicion of retinoblastoma. Histological examination showed retrolental fibrovascular tissue and retinal dysplasia. Immunoreactive opsin was detected in the innermost structures and in photoreceptor-like cells of rosettes. We conclude that photoreceptor cells differentiated to express opsin, even when neighbouring cells were abnormally arranged. An immunocytochemical study of glial fibrillary acidic protein demonstrated glial proliferation in the inner layer of the retina but not in the preretinal space.  相似文献   
45.
Influenza virus (IFV) was inactivated by treatment with degranulated fluid (DF) or myeloperoxidase (MPO) from human polymorphonuclear leukocytes in the presence of H2O2. Hemagglutinin and neuraminidase activities of the virus were also reduced by DF treatment. In addition, treatment with DF or MPO in the presence of H2O2 resulted in delayed migration of viral proteins in SDS-PAGE, indicating extensively modified viral proteins. Parallel with this aberrant migration, the radioactivity of each protein band on SDS-PAGE using [35S]methionine-labeled IFV was greatly reduced. Moreover, some of the modified viral protein did not migrate. A small amount of acid-soluble degraded viral peptide was also generated. The modification of the proteins was exhibited in all major viral proteins, including the inner proteins in the envelope. These results suggest that inactivation of IFV and protein modification by DF is due to MPO present in DF.  相似文献   
46.
47.
The pharmacokinetics and metabolism of carmofur (HCFU) were studied. Sixty-six patients were administered 100 mg of HCFU orally, and the plasma levels of the HCFU fraction (HCFUf) and 5-fluorouracil (5-FUra) were determined at 0, 1, 2, 4 and 6 hours. The average half-life of HCFUf and 5-FUra were 1.05 and 1.31 hours, and the average areas under the curves (AUC) of the plasma concentration were 6.51 hr X mcg/ml and 0.46 hr X mcg/ml, respectively. Surgical specimens of the tumors were obtained about three hours after the administration and assayed for HCFUf. 5-FUra fluorodeoxyuridine-monophosphate (FdUMP), deoxyuridine-monophosphate (dUMP), total thymidylate synthetase (TS total), and non-FdUMP-bound free enzyme (TS free). The TS inhibition rate (IR) was calculated by the follow method: IR = (TS total-TS free)/TS total X 100 levels of the TS total varied from not-detected (less than 0.10 pmol/g) to 20.5 pmol/g. The average FdUMP: dUMP ratio was 3.44 X 10(3), However, more than 80% inhibitions of TS were observed in nine cases (21.4%). The correlation indicates between TS IR and tissue FdUMP level or FdUMP: dUMP ratio were 0.57 and 0.62 in ovarian malignancies respectively. No significant correlations were observed between TS inhibition and levels of tissue 5-FUra or AUC of 5-FUra.  相似文献   
48.
The present study attempted to construct the Japanese version of Revised Self-Monitoring Scale (Lennox & Wolfe, 1984). Factor analysis of this scale yielded two factors: 1) Sensitivity to expressive behavior of others, 2) Ability to modify self-presentation. This scale and its two factors had acceptable internal consistency: these results were almost similar with the original study. In correlational analyses with other personality measures, this scale correlated positively with both Private and Public Self-Consciousness Scale and Maudsley Personality Inventory-E Scale, but positively or negatively with some scales of Yatabe-Guilford Personality Inventory (e.g., G, S: positively. I, T: negatively.). Moreover the correlations between the two factors and the above mentioned measures provided interesting results. The availability of this scale was discussed.  相似文献   
49.
The lenses of ICR/f-strain rats with hereditary cataract were monitored in situ by laser Raman spectroscopy. The lenses used were within the age of 3-10 weeks before lens opacification became manifest. The reduction of protein SH group content and the increase of protein S-S bond content were observed in ICR/f rats in the precataractous stage. No significant change in the water content was observed.  相似文献   
50.
This study was designed to investigate the effect of morphine on formalin-induced nociceptive responses in streptozotocin (STZ) induced-diabetic mice, noninsulin-dependent genetically diabetic db/db mice and their respective controls (ddY and +/+). In nondiabetic (ddY and +/+) mice, morphine (1–10 mg/kg, PO) dose dependently attenuated the biphasic nociceptive responses induced by SC injection of formalin to the hindpaw, demonstrating equipotency on both the first and second phases. Para-chlorophenylalanine (800 mg/kg × 2, PO) and pindolol (1 mg/kg, IP) reduced the effect of morphine on the first phase, sulpiride (10 mg/kg, IP) abolished the effect on both phases, while ketanserin (1 mg/kg, IP) had no effect. In STZ (200 mg/kg, IP)-diabetic mice, morphine weakly attenuated the nociception in comparison to control ddY mice, whereas it had comparable effects in both the first and second phases of control +/+ mice and db/db mice. The serotonergic agonist, meta-chlorophenylpiperazine (0.32–3.2 mg/kg, PO), dose dependently attenuated the biphasic nociceptive responses to formalin in both phases of diabetic mice; however, FR64822, a dopaminergic compound (0.1–10 mg/kg, PO), had little effect. We speculate that activation of both dopaminergic (DA)- and serotonergic-mediated mechanisms are potentially responsible for the effect of morphine on the first phase, while the DA-mediated effect is involved in the second phase. The DA-mediated mechanism, but not the serotonin-mediated one, appears to be altered in both STZ-diabetic and db/db mice. These results suggest that the attenuated effects of morphine might be due to a dopaminergic dysfunction in STZ mice, and that there might be other mechanisms compensating for this attenuation of dopaminergic function in db/db mice.  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