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   3901篇
  免费   245篇
  国内免费   9篇
耳鼻咽喉   43篇
儿科学   170篇
妇产科学   67篇
基础医学   464篇
口腔科学   275篇
临床医学   300篇
内科学   572篇
皮肤病学   83篇
神经病学   137篇
特种医学   164篇
外科学   710篇
综合类   81篇
一般理论   4篇
预防医学   189篇
眼科学   99篇
药学   439篇
  1篇
中国医学   33篇
肿瘤学   324篇
  2023年   36篇
  2022年   84篇
  2021年   147篇
  2020年   86篇
  2019年   98篇
  2018年   141篇
  2017年   110篇
  2016年   123篇
  2015年   136篇
  2014年   176篇
  2013年   242篇
  2012年   312篇
  2011年   308篇
  2010年   168篇
  2009年   153篇
  2008年   186篇
  2007年   175篇
  2006年   124篇
  2005年   92篇
  2004年   94篇
  2003年   69篇
  2002年   72篇
  2001年   73篇
  2000年   50篇
  1999年   55篇
  1998年   40篇
  1997年   43篇
  1996年   45篇
  1995年   31篇
  1994年   26篇
  1993年   20篇
  1992年   53篇
  1991年   39篇
  1990年   39篇
  1989年   50篇
  1988年   31篇
  1987年   44篇
  1986年   32篇
  1985年   30篇
  1984年   31篇
  1983年   28篇
  1982年   22篇
  1981年   22篇
  1980年   21篇
  1979年   20篇
  1977年   23篇
  1976年   20篇
  1975年   19篇
  1974年   24篇
  1973年   16篇
排序方式: 共有4155条查询结果,搜索用时 15 毫秒
61.
Virus Genes - Citrus yellow mosaic badnavirus (CMBV) causes mosaic disease in all economically important citrus cultivars of India, with losses reaching up to 70%. CMBV belongs to the genus...  相似文献   
62.
Oral and Maxillofacial Surgery - To compare the intraoperative utility of bur and saw and to examine the pattern of lingual split during bilateral sagittal split osteotomy of mandible. This study...  相似文献   
63.
Carbon doping from a Ti precursor in TiO2 synthesized by a hydrothermal method was studied. The structural, optical and morphological study of the deposited material was carried out using X-ray diffraction, UV-vis spectroscopy and scanning electron microscopy characterization techniques. The elemental composition of the TiO2 deposited with different precursor concentrations was studied using X-ray photoelectron spectroscopy and electron dispersive X-ray spectroscopy. The amount of elemental carbon in the TiO2 matrix is found to be increased as the Ti precursor concentration is increased, which strengthens the proposed idea of carbon doping via a Ti precursor.

Interstitial carbon doping is possible directly from a Ti precursor (titanium(iv) isopropoxide) without using any other carbon source.  相似文献   
64.
Accurate assays of plant antioxidants and other phytochemicals require efficient extraction conditions and enable rigorous assessments of crop varieties and production systems. This study assessed the extraction of phytochemicals and antioxidants from conventionally or organically grown red and golden beets (Beta vulgaris L.), using twenty solvent (S1–S20) mixtures containing water, methanol, and ethanol alone or with acids (ascorbic, formic, acetic). Red beetroot extracted with methanol with or without acid had the highest betanin content (2791.0 μg/g and 8222.3 μg/g of fresh weight [FW], respectively) and golden beetroot extracted with methanol/ascorbic acid/water had the highest vulgaxanthin I (193.7 μg/g and 15.0 μg/g of FW, respectively). The radical-scavenging activity and total phenolics in beetroot extracts reflected the different extraction efficiency of each solvent. UHPLC-QTOF-MS was used to identify twenty-seven phytochemicals, including 23 betalains, 2 amino acids, and 2 phenolic acids. Chemometric approaches discriminated the beet varieties and different extracts within one variety based on the composition and abundance of the key phytochemicals. The red beetroot extracted with aqueous ethanol with or without acid (S5, S7, S8, S9), and golden beetroot extracted with methanol-containing solvents (S15 for conventionally and S20 for organically) had the highest levels of phytochemicals, suggesting that these conditions efficiently extract key phytochemicals.  相似文献   
65.
66.
A urethrocutaneous fistula is a common complication after hypospadias repair, but congenital fistula is a rare anomaly. We present a 16-year-old boy with this unusual anomaly. Its etiology, embryology, and management are discussed in brief.KEY WORDS: Adolescent, congenital fistula of penile urethra, urethroplasty  相似文献   
67.
68.
Unequal accumulation of drugs in pigmented and nonpigmented iris has been known for some time. However, at low concentrations of the sympathetic neurotransmitter norepinephrine, the accumulation is equal in both types of irides. The spontaneous and potassium-induced release of 3H was studied in isolated rabbit irides labeled with 0.1 micron [3H]norepinephrine ([3H]NE). The spontaneous outflow and the tissue 3H content were similar in both types of irides, but the potassium-induced release was significantly higher in nonpigmented iris. When irides were labeled with [3H]NE in the presence of 1 micron desmethylimipramine, the potassium-induced release was still significantly higher in nonpigmented than in pigmented iris, although the tissue 3H content was higher in the latter. Subcellular distribution of [3H]NE in both types of irides is presented. The data indicate that [3H]NE is distributed unequally in both types of irides in spite of equal tissue accumulation. The binding of NE by the pigment cell suggests an additional site of loss, or site of uptake, of the transmitter in melanin-containing tissues. The physiological significance of such an unequal release in relation to the evolutionary adaptation of the eye to light is discussed.  相似文献   
69.
70.
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