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   6426篇
  免费   506篇
  国内免费   117篇
耳鼻咽喉   16篇
儿科学   100篇
妇产科学   531篇
基础医学   993篇
口腔科学   82篇
临床医学   323篇
内科学   573篇
皮肤病学   153篇
神经病学   535篇
特种医学   118篇
外科学   314篇
综合类   643篇
预防医学   1599篇
眼科学   28篇
药学   541篇
  4篇
中国医学   143篇
肿瘤学   353篇
  2024年   6篇
  2023年   112篇
  2022年   188篇
  2021年   300篇
  2020年   313篇
  2019年   267篇
  2018年   263篇
  2017年   264篇
  2016年   277篇
  2015年   264篇
  2014年   481篇
  2013年   508篇
  2012年   405篇
  2011年   458篇
  2010年   354篇
  2009年   308篇
  2008年   262篇
  2007年   279篇
  2006年   237篇
  2005年   185篇
  2004年   213篇
  2003年   150篇
  2002年   111篇
  2001年   87篇
  2000年   80篇
  1999年   104篇
  1998年   44篇
  1997年   46篇
  1996年   43篇
  1995年   43篇
  1994年   34篇
  1993年   31篇
  1992年   34篇
  1991年   26篇
  1990年   24篇
  1989年   25篇
  1988年   20篇
  1987年   12篇
  1986年   10篇
  1985年   30篇
  1984年   48篇
  1983年   14篇
  1982年   16篇
  1981年   26篇
  1980年   12篇
  1979年   8篇
  1978年   7篇
  1977年   5篇
  1976年   6篇
  1974年   4篇
排序方式: 共有7049条查询结果,搜索用时 46 毫秒
1.
2.
3.
卵巢过度刺激综合征是辅助生殖技术常见的并发症,通常在排卵后2周或2周以上发生。然而自发性卵巢过度刺激综合征极其罕见,一些病例报道表明,自发性卵巢过度刺激综合征的发生与卵泡刺激素受体突变、高人绒毛膜促性腺激素水平、高促甲状腺激素水平、促性腺激素垂体腺瘤等有关。现报告1例双胎妊娠合并自发性卵巢过度刺激综合征的病例,并进一步探讨自发性卵巢过度刺激综合征的可能病因、诊断和治疗原则。  相似文献   
4.
目的:探讨二补助育汤对胚胎着床障碍模型小鼠子宫内膜形态及血管生成素-1(Ang-1)mRNA、血管内皮生长因子(VEGF)mRNA的表达和定位的影响。方法:24只ICR雌性小鼠随机分为空白组、模型组、戊酸雌二醇组、二补助育汤组,每组6只,用米非司酮建立胚胎着床障碍动物模型,各组给予相应药物灌胃,妊娠第5天处死小鼠后,检测各组妊娠率、平均着床位点数、子宫内膜Ang-1和VEGF mRNA表达量及其蛋白定位。结果:模型组小鼠平均胚胎着床位点数、Ang-1 mRNA、VEGF mRNA表达量明显低于空白组(均P<0.05);与模型组比较,二补助育汤组平均胚胎着床位点数、Ang-1 mRNA、VEGF mRNA表达量显著提高(均P<0.05)。结论:二补助育汤可提高子宫内膜Ang-1和VEGF蛋白表达量,促进子宫内膜血管生成,从而提高子宫内膜容受性。  相似文献   
5.
Accurate modeling of intratumor heterogeneity presents a bottleneck against drug testing. Flexibility in a preclinical platform is also desirable to support assessment of different endpoints. We established the model system, OHC-NB1, from a bone marrow metastasis from a patient diagnosed with MYCN-amplified neuroblastoma and performed whole-exome sequencing on the source metastasis and the different models and passages during model development (monolayer cell line, 3D spheroid culture and subcutaneous xenograft tumors propagated in mice). OHC-NB1 harbors a MYCN amplification in double minutes, 1p deletion, 17q gain and diploid karyotype, which persisted in all models. A total of 80–540 single-nucleotide variants (SNVs) was detected in each sample, and comparisons between the source metastasis and models identified 34 of 80 somatic SNVs to be propagated in the models. Clonal reconstruction using the combined copy number and SNV data revealed marked clonal heterogeneity in the originating metastasis, with four clones being reflected in the model systems. The set of OHC-NB1 models represents 43% of somatic SNVs and 23% of the cellularity in the originating metastasis with varying clonal compositions, indicating that heterogeneity is partially preserved in our model system.  相似文献   
6.
ObjectiveIn traditional medicine, the seeds of Thai Mucuna pruriens (T-MP) are used to treat male dysuria and are believed to enhance fertility. However, information pertaining to the toxicity of T-MP and its interaction with other properties is limited. This study was thus conducted to evaluate the antioxidant capacity and subacute toxicity of T-MP in the reproductive system.MethodsTotal phenolic content and antioxidant capacity of T-MP seed extract were determined using total phenolic content, 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays. Male and female adult rats were treated orally with T-MP at a dosage of 150 or 300 mg/kg body weight for 14 consecutive days. Sex hormones and functional parameters in the liver and kidney were evaluated. Histopathology of all tissue was conducted using Masson’s trichrome staining. Sperm parameters, including concentration, morphology, acrosome reaction status and DNA damage, were also examined. Expression of tyrosine phosphorylated protein (TyrPho), androgen receptor and A-kinase-anchoring protein 4 (AKAP4) were investigated using the Western blot technique.ResultsT-MP seed extract contained phenolic compounds and exhibited high antioxidant capacity with no toxicity at the tested doses. It did not affect liver or kidney function parameters in the male rats, but increased estradiol, aspartate aminotransferase and alanine aminotransferase levels in the females. Additionally, it decreased serum progesterone and alkaline phosphatase levels in female rats. Serum and intratesticular testosterone levels were significantly lower in male rats that received a high dosage of T-MP. Histopathological changes were not observed in any tissue treated with T-MP. T-MP also significantly increased sperm concentration (but did not affect sperm parameters), and enhanced testicular TyrPho protein and androgen receptor and expression of AKAP4 in sperms.ConclusionT-MP seed extract exhibited antioxidant capacity and was not harmful to reproductive tissues. It also had a phytoestrogenic effect on females and increased the expression of testicular and sperm markers of male fertility.  相似文献   
7.
IntroductionLung cancer is the leading cause of cancer-death worldwide. The U.S. Preventative Services Task Force (USPTSF) approved screening for current or former smokers aged 55–80 based on the results of the National Lung Screening trial (NLST). Following the NLST, new evidence has emerged from clinical trials and updates to previous trials prior to the anticipated update to the USPSTF guideline. We review the new evidence on lung cancer screening with low dose computed tomography (LDCT) and the surgical implications.MethodsA review of new literature was performed pertaining to lung cancer screening since implementation of UPSTF guidelines. Articles for inclusion were identified by both authors’, then search of the Pubmed and Cochrane database was performed from January 1st, 2013 through February 4th, 2020 using the MeSH search terms: “lung cancer”; “screening”; “low dose CT”. The results of these studies are summarized.ResultsWe identified multiple prospective randomized control trials and meta-analysis since the NLST supporting lung cancer-specific mortality with screening. We identified new nodule classification systems and the development of risk-models which may reduce false positive rates and identify high risk patients not currently eligible for screening. Finally, we discussed the surgical implications of screening.ConclusionNew data supports NLST findings and show ongoing benefit to LDCT for lung cancer screening. Standardized LDCT screening classification has been shown to reduce harm and lower false positive rates. Further study is needed regarding use of risk-modeling. Screening will require an increase in the thoracic workforce to accommodate the amount of surgically operable cancers.  相似文献   
8.
ObjectiveWe analyse how reproductive health strategies have been incorporated into the everyday activities of the services and the resulting transformation of professional and user practices.MethodCartographic research taking a multi-sited ethnographic approach that seeks to reveal the processes of transformation. Data generation techniques featuring participant observation and situated interviews. Discourse analysis of the text corpus using three analytical axes based on three main lines of action promoted by the strategies.ResultsWe identified transformations in: 1) demedicalisation: an increase in midwives’ know-how and autonomy, changes in episiotomy practice and the facilitation of bonding practices; 2) warmth of care: incorporation of women's needs and expectations and improvements in the comfortableness of birth settings, especially in assistance at physiological birth; and 3) participation: actions that foster shared decision-making and the involvement of the persons accompanying women in labour.ConclusionsAbove all, transformation is visible in the incorporation of new attitudes, sensibilities and practices that have developed around the old structures, especially during physiological childbirth. The more technological areas have been less permeable to change. Risk management in decision-making and addressing diversity are identified as areas where transformation is less evident.  相似文献   
9.
10.
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