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   6224篇
  免费   263篇
  国内免费   28篇
耳鼻咽喉   31篇
儿科学   101篇
妇产科学   75篇
基础医学   746篇
口腔科学   145篇
临床医学   438篇
内科学   1544篇
皮肤病学   90篇
神经病学   535篇
特种医学   275篇
外科学   1010篇
综合类   26篇
预防医学   160篇
眼科学   97篇
药学   488篇
中国医学   12篇
肿瘤学   742篇
  2023年   28篇
  2022年   63篇
  2021年   102篇
  2020年   67篇
  2019年   56篇
  2018年   119篇
  2017年   71篇
  2016年   103篇
  2015年   103篇
  2014年   132篇
  2013年   189篇
  2012年   290篇
  2011年   249篇
  2010年   140篇
  2009年   131篇
  2008年   282篇
  2007年   265篇
  2006年   278篇
  2005年   249篇
  2004年   253篇
  2003年   238篇
  2002年   246篇
  2001年   283篇
  2000年   225篇
  1999年   222篇
  1998年   76篇
  1997年   71篇
  1996年   44篇
  1995年   55篇
  1994年   46篇
  1993年   49篇
  1992年   156篇
  1991年   149篇
  1990年   149篇
  1989年   153篇
  1988年   125篇
  1987年   135篇
  1986年   137篇
  1985年   93篇
  1984年   81篇
  1983年   54篇
  1980年   33篇
  1979年   63篇
  1978年   37篇
  1977年   40篇
  1972年   29篇
  1971年   37篇
  1969年   33篇
  1968年   34篇
  1967年   27篇
排序方式: 共有6515条查询结果,搜索用时 15 毫秒
11.
The carcinogenic activity of endogenously synthesized N-nitrosobis(2-hydroxypropyl)amine(BHP) was investigated in male Wistar rats administered bis(2-hydroxypropyl)amine(BHPA) mixed in powder diet at a concentration of 1%, and sodiumnitrite (SN) dissolved in distilled water at concentrationsof 0.15 and 0.3%, for 94 weeks. Urinary excretion of BHP wasdetected in rats given 1% BHPA and 0.3% SN but not in the groupsreceiving either of these precursors alone. Nasal cavity, lung,esophagus, liver and urinary bladder tumors were found in animalstreated with combinations of 1% BHPA and 0.15 or 0.3% SN, suggestingthat the target organs of the endogenously synthesized BHP aresimilar to those affected when the carcinogen is administeredexogenously. The incidences of nasal cavity and lung tumorsreached 74 and 58% in rats given 1% BHPA and 0.3% SN, respectively.Tumors at sites other than target organs were only found atlevels similar to those previously reported for spontaneoustumors in male Wistars. The present results clearly indicatedthe tumor inducibility of a nhrosatable amine, BHA, throughan endogenous nitrosation by feeding to rats in conjunctionwith nitrite, and provide further suggestive evidence that endogenousnitrosations of environmental nitrosatable amines can be a potentialrisk factor in human cancer development.  相似文献   
12.
13.
14.
We report here an unusual case of fibrous histiocytoma in which an area of xanthogranuloma was observed histologically. Our case suggests that adult xanthogranuloma is a variant of fibrous histiocytoma.  相似文献   
15.
We identified the possible endogenous factor effective to modulate the binding of [3H]-labeled excitatory amino acid agonists and antagonists in the 100,000 x g supernatant of Triton X-100 (0.01%)-treated cell membranes from frog spinal cords. The factor inhibited the binding of [3H]glutamate to Triton X-100-treated cell membranes, to which the binding capacity of [3H]glutamate increased much more than that to intact cell membranes. The binding capacities of [3H]AMPA (an AMPA type agonist) and [3H]CPP (an NMDA type antagonist) to cell membranes remained low by Triton treatment, but they were enhanced significantly by the addition of the factor. The effect of the factor on the [3H]kainate binding was hardly observable. The factor may provide key information on receptor structures and the classification of receptor types concerning excitatory amino acids in the mammalian central nervous system.  相似文献   
16.
This work describes a lambda phage expression system, lambda foo, that produces foreign proteins fused to the surface of the virus particle. The lambda foo vector has multiple cloning sites for the insertion of a foreign DNA fragment and color selection for recombinants. Foreign proteins are fused to the C terminus of a truncated phage tail protein, pV, by a peptide linker. Conditional chain termination allows the assembly and fusion of multisubunit proteins. We have attached the complete Escherichia coli beta-galactosidase and the plant Bauhinia purpurea agglutinin by cloning their genes into the vector. The constructs express functionally active proteins on the phage particle surface and have been purified by affinity chromatography with an antibody for beta-galactosidase and a mucin as a ligand for Bauhinia purpurea agglutinin.  相似文献   
17.
A vascularized rib strut based on the anterior intercostal branch of the internal mammary artery was applied to provide rigid internal fixation of the chest wall after correction of pectus excavatum. The procedure is simple and has substantial advantages when compared with techniques using metallic struts or nonvascularized free rib grafts.  相似文献   
18.
The risk of cerebral infarction (CI) in an individual is dependent on the interplay between genetic risk factors and environmental influences. Binding of thromboxane A2 (TXA2) to its receptor (TP) modulates thrombosis/hemostasis and plays a significant role in the pathogenesis of CI. The aim of the present study was to investigate the relationship between human TP gene single nucleotide polymorphisms (SNPs) and haplotypes and CI in a Japanese population. A genetic association study was performed in 194 CI patients and 365 non-CI subjects by specifically characterizing 6 SNPs in the human TP gene (rs2271875, rs768963, rs2238634, rs11085026, rs4523 and rs4806942). Analysis demonstrated that there were significant differences in the overall distribution of genotypes and dominant or recessive models of rs2271875 and rs768963 between the CI and the non-CI groups. Multiple logistic regression analysis revealed that the C allele of rs768963 was significantly associated with CI (p = 0.029), even after adjusting for confounding factors (odds ratio: 2.41). Further, the C-T-C haplotype of rs768963-rs2238634-rs4806942 was significantly more frequent in the CI group (23.0%) than in the non-CI group (17.7%). These results suggest that specific SNPs and haplotypes may have utility as genetic markers for the risk of CI and that TP or a neighboring gene is associated with the increased susceptibility to CI.  相似文献   
19.
An ulnar recurrent adipofascial flap was raised and turned over to reconstruct massive defects around the elbow and forearm after wide resection of malignant tumours. Compared to the fasciocutaneous flap, the ulnar recurrent adipofascial flap has the following advantages: (1) a larger flap can be harvested without the problem of primary closure of the donor site, (2) the contour and scar of the donor site is reasonably acceptable since no tension is presented, (3) the flap can be turned over to cover a wider area, and (4) debulking of the flap can be performed during the operation if needed. The rotation arc of the ulnar recurrent adipofascial flap reaches a wide region, including the distal one-half of the upper arm, the elbow, and the proximal two-thirds of the forearm. Sensory deficit in the forearm was avoided in our patients because meticulous separation and preservation of the medial cutaneous nerve of the forearm was achieved without jeopardising the blood supply to the flap. The ulnar recurrent adipofascial flap is an easy and reliable option for one-stage reconstruction of massive defects around the elbow.  相似文献   
20.
Mortality rate of gastric cancer in Japan had been the highest in the world. Development of early detection and effective treatment was the most impor-tant social demand. For the early detection, Japan de-veloped “double contrast X-ray”, “endoscopy and en-doscopic biopsy”, and “mass screening system”. The Japanese nationwide registry collected data of 273,142 gastric cancer patients in the last 30 years. By the ef-forts of early detection, proportion of Stage I cancer increased from 22.5% to 58.1% in the registry. Cu-mulative 5 year survival rate of resected cases was improved from 37.5% (1962) to 68.8% (1991). Im-provement was remarkable for Stage-II; from 47.7% to 70.3%, and for Stage-III, from 26.4% to 45.0%.  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