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   3701篇
  免费   155篇
  国内免费   12篇
耳鼻咽喉   13篇
儿科学   171篇
妇产科学   48篇
基础医学   477篇
口腔科学   80篇
临床医学   265篇
内科学   673篇
皮肤病学   70篇
神经病学   271篇
特种医学   111篇
外科学   479篇
综合类   92篇
一般理论   1篇
预防医学   229篇
眼科学   203篇
药学   421篇
中国医学   24篇
肿瘤学   240篇
  2023年   30篇
  2022年   81篇
  2021年   137篇
  2020年   72篇
  2019年   74篇
  2018年   108篇
  2017年   66篇
  2016年   97篇
  2015年   110篇
  2014年   126篇
  2013年   171篇
  2012年   255篇
  2011年   263篇
  2010年   134篇
  2009年   120篇
  2008年   185篇
  2007年   204篇
  2006年   185篇
  2005年   156篇
  2004年   138篇
  2003年   132篇
  2002年   143篇
  2001年   120篇
  2000年   104篇
  1999年   74篇
  1998年   30篇
  1997年   24篇
  1996年   38篇
  1995年   15篇
  1994年   6篇
  1993年   11篇
  1992年   31篇
  1991年   32篇
  1990年   39篇
  1989年   45篇
  1988年   40篇
  1987年   36篇
  1986年   29篇
  1985年   29篇
  1984年   25篇
  1983年   22篇
  1982年   15篇
  1981年   11篇
  1980年   14篇
  1979年   24篇
  1977年   13篇
  1974年   9篇
  1973年   6篇
  1971年   7篇
  1970年   9篇
排序方式: 共有3868条查询结果,搜索用时 15 毫秒
1.
The aim of this study was to examine the predictors of long-term survival (>24 months) in patients with gall bladder cancer. A retrospective review of 117 cases of gall bladder cancer resected between 1989 and 2000. The resections included 80 simple cholecystectomies and 37 extended procedures. Patients with survival >24 months (n=44) were compared with those having survival <24 months (n=73) for 17 prognostic factors. Overall median survival was 16 months with a 5-year survival of 27%. T status (P=.000) and adjuvant chemoradiotherapy (P=.001) were independent predictors of long-term survival. Survival advantage was seen in T3N+ve disease (P=.007) with extended procedures. Complete (R0) resection was attained in 30 patients with a 5-year survival advantage of 30% as compared with incomplete (R1) resection (P=.0002). Adjuvant chemoradiotherapy improved survival in simple cholecystectomy group (P=.0008) but no advantage was seen after extended procedures. Stage III (P=.001) and node-positive disease (P=.0005) had significant benefit with adjuvant therapy. Poor differentiation and vascular invasion were associated with poor long-term survival. R0 resection was associated with prolonged survival. Extended procedures improved survival in patients with T3N+ve disease. Addition of chemoradiotherapy made significant improvement in long-term survival in stage III and node-positive lesions and in patients undergoing simple cholecystectomy. R0 resection predicted long-term survival in gall bladder cancer. T3 N+ve disease had better survival after extended procedures. Adjuvant chemoradiotherapy improved survival in stage III and node-positive disease. Poor differentiation and vascular invasion were adverse predictors of survival.  相似文献   
2.
Histomorphological responses of the ovary of a freshwater percoid fish, Colisa (T.) fasciatus, to endosulfan or thiodan EC 35 treatment, a popular pesticide, have been described. In addition, general behavioral changes of the fishes after treatment have also been recorded. Adult sexually mature females were used in the present study and all fish were in the prespawning phase of the ovarian cycle. The experiment was conducted under natural room temperature and day-night length for 30 days. Experimental fish were maintained in 1 ppm endosulfan solution, which was changed on alternate days after feeding with minced goat liver. Treated fish revealed that (a) the ovarian activity was retarded; (b) the ovarian wall became thicker; (c) the diameter of oogonia and stage I oocytes was not altered but that of stage II and III oocytes was greatly reduced; (d) the percentage of oogonia, stage I, and atretic oocytes increased considerably but that of stage II and III oocytes diminished significantly; and (e) yolk in the stage III oocytes appeared clumped and damaged.  相似文献   
3.
Integrated Child Development Services (ICDS) is India's most comprehensive programme to increase the survival rate and enhance the health, nutrition, and learning opportunities of pre-school children and their mothers through a package of services. The present study was carried out to measure the impact of the preschool education component of the ICDS on the cognitive development of children in the age group of 3-5 years. The study design used was case/control (ICDS attending children v. Non-ICDS). Results of the study revealed the ICDS Anganwadi attendance had positive influence on the cognitive development of children. The mean cognitive score of the attenders was 40.7 as against a mean score of 30.3 in the case of non-attenders.  相似文献   
4.
Cyclohexanone was condensed with N-hydroxymethyl benzamide in conc. sulphuric acid to give alpha-methyl-benzamido-cyclohexanone (I). The reaction of (I) with thiosemicarbazide in ethanol resulted in alpha-methyl-benzamido-cyclohexanone thiosemicarbazone (II). Condensation of (II) with various aromatic aldehydes in the presence of ethanol afforded alpha-methyl-benzamido-alpha'-substituted-styryl-cyclohexanone thiosemicarbazones (III) in yields ranging from 40 to 50 percent. The compounds exhibited pronounced antiimplantation activity in female albino rats.  相似文献   
5.
6.
7.
8.
9.
Cytogenetics or the study of chromosomes has been an important tool in oncology. It localizes the abnormality on a particular chromosome segment as such but, the molecular analysis on the other hand focuses the exact gene of interest. Hence both are complimentary. Classical cytogenetics in combination with recent molecular techniques has given rise to various molecular cytogenetic analytical techniques such as florescent in-situ hybridization (FISH), spectral karyotyping (SKY) and comparative genomic hybridization (CGH). The role of telomeres and its concerned enzyme telomerase is important in carcinogenesis. This article summarizes the various cytogenetic techniques and presents an overall view of the importance of cytogenetcs in head and neck cancer.  相似文献   
10.
Entamoeba histolytica possesses significant acid phosphatase activity as compared to alkaline phosphatase activity. The acid phosphatase activity in the amoebic cells eluted at higher saline concentration as three distinct peaks at 200, 300 and 400 mM sodium chloride.  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