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   5296篇
  免费   266篇
  国内免费   18篇
耳鼻咽喉   16篇
儿科学   54篇
妇产科学   91篇
基础医学   717篇
口腔科学   171篇
临床医学   328篇
内科学   1416篇
皮肤病学   147篇
神经病学   307篇
特种医学   232篇
外科学   822篇
综合类   36篇
预防医学   156篇
眼科学   56篇
药学   388篇
中国医学   13篇
肿瘤学   630篇
  2023年   29篇
  2022年   56篇
  2021年   93篇
  2020年   66篇
  2019年   77篇
  2018年   97篇
  2017年   80篇
  2016年   110篇
  2015年   96篇
  2014年   128篇
  2013年   165篇
  2012年   259篇
  2011年   280篇
  2010年   154篇
  2009年   141篇
  2008年   231篇
  2007年   243篇
  2006年   236篇
  2005年   249篇
  2004年   248篇
  2003年   250篇
  2002年   257篇
  2001年   169篇
  2000年   200篇
  1999年   152篇
  1998年   55篇
  1997年   64篇
  1996年   65篇
  1995年   44篇
  1994年   46篇
  1993年   47篇
  1992年   121篇
  1991年   108篇
  1990年   105篇
  1989年   110篇
  1988年   89篇
  1987年   78篇
  1986年   76篇
  1985年   75篇
  1984年   71篇
  1983年   43篇
  1982年   27篇
  1981年   24篇
  1980年   16篇
  1979年   26篇
  1978年   32篇
  1977年   30篇
  1975年   18篇
  1973年   15篇
  1969年   17篇
排序方式: 共有5580条查询结果,搜索用时 15 毫秒
61.
Background: Nevus of Ota is common in Japanese women, but most patients are not examined ophthalmologically. Methods: We performed ophthalmologic examinations on 16 Japanese women who had had bluish pigmentation in the periorbital region, sclera, and conjunctiva since birth. Results: Fifteen patients had unilateral involvement, and one had bilateral lesions. The visual acuities were good, and the intraocular pressures were within normal range. All patients had a negative family history. Three patients had light pigmentation in the optic disc in the affected eye. Conclusion: We believe that optic disc pigmentation associated with nevus of Ota, as found in these three patients, may be common but have been rarely described.  相似文献   
62.
Repeat liver resection for recurrent colorectal liver metastases   总被引:11,自引:0,他引:11  
BACKGROUND: This study aimed to delineate the role of surgery for recurrent colorectal cancer in the liver and to identify prognosticators for better patient selection and outcome. METHODS: Data from 90 repeat hepatectomies (second = 75; third = 12; fourth = 3) for recurrent colorectal cancer were collected. RESULTS: After the second hepatectomy, the 3-and 5-year survival rates were 48% and 31%, respectively. Twenty-seven percent (20 of 75) of patients are alive without recurrence after a median follow-up of 27 months, and 9 survived more than 5 years. Four or more tumors, positive regional lymph node metastases, concomitant extrahepatic disease, and residual tumor were independent poor prognostic factors after the second hepatectomy. CONCLUSIONS: Repeat hepatectomy should be applied for recurrent colorectal cancer, when curative removal of the tumor is possible, although the benefit from treatment was limited in a patient with regional lymph node metastases, 4 or more metastases, or extrahepatic disease.  相似文献   
63.
To evaluate the effect of interferon-γ-genetransduced cells, DS mice were inoculated into their footpads with syngeneic mammary adenocarcinoma SC42 admixed with interferon-γ producing mammary adenocarcinoma SC115Kγ, which had been established by an interferon-γ-gene transduction in another syngeneic mammary adenocarcinoma SC115 using retroviral vectors. These mice rejected both tumor cells and developed resistance to subsequent challenges with either SC115 or SC42 cells inoculated into their opposite posterior footpads. These results thus indicate that systemic immunological memory to each of the independent tumor cell lines developed in these mice. Although the SC42 cells admixed with irradiated SC115Kγ cells were rejected by these mice, the SC42 cells admixed with irradiated SC115neoR, in which the neo-gene had been transduced, were observed to proliferate. Tumor rejection was reversed by an in vivo administration of anti-interferon-γ antibody, thus suggesting that locally produced interferon-γ plays an important role in tumor elimination and immunological memory induction. In conclusion, interferon-γ-gene-transduced tumor cells are therefore considered to have a therapeutic potential for other types of malignant tumor cell lines.  相似文献   
64.
In order to clarify the characteristic features of myelitis with atopic dermatitis (AD), we compared the clinical, immunological and MRI findings between 14 myelitic patients with AD and 12 myelitic patients without AD. The myelitic patients with AD showed the following distinct features, compared with those without AD. (1) A preferential involvement of the cervical cord, as shown by neurologic as well as MRI examinations (14/14 vs. 5/12; P=0.0012), (2) paresthesia/dysesthesia as the predominant symptoms and a rare occurrence of definite muscle weakness (0/14 vs. 5/12; P=0.0120) and dysuria (1/14 vs. 8/12; P=0.0029), (3) a lower Expanded Disability Status Scale score (mean, 1.5 vs. 3.5; P=0.0018), (4) normal cerebrospinal fluid (CSF) findings including those for the IgG index and oligoclonal IgG bands and (5) a persistence of neurologic symptoms and MRI lesions during the follow-up periods (mean, 17 months). In addition, both the serum total IgE level and the frequency of specific IgE to Dermatophagoides farinae were significantly higher in the myelitic patients with AD (median IgE=1266 U/ml, specific IgE 14/14) than in those without AD (145 U/ml, P=0.0034 and 8/12, P=0.0331, respectively) and in 40 healthy controls (86 U/ml, P<0.0001 and 12/40, P<0.0001, respectively). Since myelitis with AD has distinct features and atopy to mite antigens appears to be the underlying cause of this condition, it may therefore be a distinct subtype of myelitis.  相似文献   
65.
RID=" ID=" <E5>Correspondence to:</E5> J. Yamamoto, M.D.  相似文献   
66.
We studied the effect of NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl) ureido]methyl]cyclohexane), a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on intracellular cholesterol esterification and the secretion of apolipoprotein B100 (apoB)-containing lipoprotein and bile acids in the human hepatoma cell line HepG2. NTE-122 markably inhibited [3H]oleate incorporation into cholesteryl esters in HepG2 cells incubated with 5 microg/ml 25-hydroxycholesterol as a stimulus for ACAT (IC50=6.0 nM). On the other hand, NTE-122 did not affect [3H]oleate incorporation into triglycerides and phospholipids and [14C]acetate incorporation into cholesterol. The stimulation of ACAT by 25-hydroxycholesterol caused significant increases in the secretion of radiolabeled cholesteryl esters, radiolabeled triglycerides and apoB mass. NTE-122 pronouncedly inhibited the secretion of radiolabeled cholesteryl esters in proportion to the inhibition of cellular cholesterol esterification, and it significantly reduced the secretion of radiolabeled triglycerides and apoB mass in HepG2 cells incubated with 25-hydroxycholesterol. Furthermore, NTE-122 increased the secretion of bile acids synthesized from [14C]-cholesterol. These results suggest that NTE-122 is capable of exhibiting anti-hyperlipidemic effects by reducing both the cholesterol content and the amount of secreted very low-density lipoprotein and enhancing the excretion of bile acid from the liver.  相似文献   
67.
We investigated the effects of a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl)ureido]methyl]cyclohexane), on ACAT activities in macrophages originating from several species and high-density lipoprotein (HDL)-induced cholesterol efflux in phorbol 12-myristate 13-acetate (PMA)-treated THP-1 cells. NTE-122 inhibited cell-free ACAT activities in human PMA-treated THP-1 cells and mouse J774.1 cells with IC50 values of 0.88 and 360 nM, respectively. NTE-122 competively inhibited the ACAT activity in PMA-treated THP-1 cells. NTE-122 also inhibited cellular ACAT activities in PMA-treated THP-1 cells, rat peritoneal macrophages and J774.1 cells with IC50 values of 3.5, 84 and 6800 nM, respectively. Furthermore, NTE-122 prevented cholesterol accumulation in PMA-treated THP-1 cells incubated with acetylated low density lipoprotein, simultaneously with HDL, while it caused accumulation of a significant amount of free cholesterol in the absence and even in the presence of HDL. NTE-122 also enhanced HDL-induced cholesterol efflux from established foam cells converted from PMA-treated THP-1 cells. These results suggest that NTE-122, capable of inhibiting macrophage ACAT activity in humans more strongly than those in the other species, exhibits anti-atherogenic effects by preventing the foam cell formation and enhancing the foam cell regression in humans.  相似文献   
68.
We report herein the rare case of a 79-year-old man who suffered permanent paraplegia after undergoing an otherwise successful total arch replacement for a ruptured aortic arch aneurysm. During cardiopulmonary bypass, perfusion to the distal aorta was maintained from the femoral artery, and postoperative aortography showed intact tributaries from the aorta including the intercostal arteries. Postoperative paraplegia is an extremely rare complication of operations on the aortic arch; however, we speculate that the paraplegia in this patient could be attributed either to a steal phenomenon involving the radicular artery, or to the anatomical particularity of the spinal cord artery described by Cole and Gutelius as the segmental system.  相似文献   
69.
We have developed a new in vitro method of quantitatively analyzing ciliary movement in the ependymal wall of the aqueduct in rats. An axial slice of the midbrain containing ependymal wall was placed in a culture dish filled with a culture medium containing latex beads 1 m in diameter at a concentration of 107 beads/ml. The movement of the beads caused by flow of culture medium generated by the to-and-fro ciliary movement was recorded by a high speed video system attached to an inverted phase-contrast microscope. Ciliary movement was expressed by the speed of the latex beads (m/s). Aqueductal ciliary movement in congenitally hydrocephalic HTX rats, congenitally hydrocephalic WIC-Hyd rats, and other normal rats was evaluated. The results suggest that in congenitally hydrocephalic WIC-Hyd rats the degree of hydrocephalus related strongly to the degree of ciliary dyskinesia, but in congenitally hydrocephalic HTX rats it did not. Considering this discrepancy, we attempted to see whether or not hydrocephalus was caused by artificial disturbance of ependymal ciliary movement in vivo. We found that continuous infusion of metavana date, an inhibitor of ciliary movement, into the III ventricle of normal Sprague-Dawley rats for 7 days induced dilatation of the ventricular system. Although the question whether or not disturbance of aqueductal ependymal ciliary movement is related to the development of human congenital hydrocephalus is debatable, the results of the present in vitro and in vivo experimental investigations appear to suggest that the disturbance of ciliary movement in the aqueduct could at least be one of the factors contributing to the inducement of hydrocephalus in experimental conditions.  相似文献   
70.
The synthesis and biological properties of 1-N-[4-(substituted)amidino and guanidino-2-hydroxybutyryl]kanamycins A and B are described. Reaction of 3,3",6'-tri-N-tert-butoxycarbonyl-amikacin with an appropriate amidinating or guanidinating reagent and subsequent deblocking gave a series of amikacin derivatives having an amidino or guanidino group on the 4"'-position. The corresponding kanamycin B analogs were also prepared by a similar procedure. Among these derivatives, 1-N-(4-formamidino- and guanidino-2-hydroxybutyryl)kanamycins A (7a and 7k) and B (11 and 14) exhibited antibacterial activity similar to the corresponding 4-amino analogs. The nephrotoxic potential of selected compounds is also briefly discussed.  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