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   8623篇
  免费   591篇
  国内免费   52篇
耳鼻咽喉   46篇
儿科学   225篇
妇产科学   269篇
基础医学   1430篇
口腔科学   183篇
临床医学   943篇
内科学   1708篇
皮肤病学   190篇
神经病学   871篇
特种医学   294篇
外国民族医学   7篇
外科学   748篇
综合类   42篇
一般理论   2篇
预防医学   738篇
眼科学   87篇
药学   671篇
中国医学   19篇
肿瘤学   793篇
  2024年   11篇
  2023年   64篇
  2022年   114篇
  2021年   219篇
  2020年   154篇
  2019年   204篇
  2018年   217篇
  2017年   175篇
  2016年   240篇
  2015年   248篇
  2014年   355篇
  2013年   425篇
  2012年   684篇
  2011年   806篇
  2010年   424篇
  2009年   385篇
  2008年   618篇
  2007年   663篇
  2006年   622篇
  2005年   589篇
  2004年   507篇
  2003年   410篇
  2002年   402篇
  2001年   62篇
  2000年   51篇
  1999年   68篇
  1998年   80篇
  1997年   80篇
  1996年   64篇
  1995年   43篇
  1994年   45篇
  1993年   36篇
  1992年   32篇
  1991年   15篇
  1990年   13篇
  1989年   8篇
  1988年   10篇
  1987年   9篇
  1986年   9篇
  1985年   15篇
  1984年   11篇
  1983年   11篇
  1982年   6篇
  1981年   5篇
  1980年   6篇
  1979年   7篇
  1976年   4篇
  1974年   9篇
  1970年   5篇
  1966年   3篇
排序方式: 共有9266条查询结果,搜索用时 15 毫秒
91.
Dietary supplements used by women during menopause are usually based on plant extracts containing isoflavonoids, daidzein and genistein. Genistein is a known inhibitor of many enzymes, including thyroid peroxidase (TPO). In the thyroid follicle, genistein acts as its alternate substrate for the formation of genistein iodinated derivatives. The aim of this study was to search for daidzein- and genistein-iodinated derivatives in urine of isoflavonoid-supplemented women. Additionally, selected phytoestrogens, steroid and thyroid hormones before and after three months of phytoestrogen supplementation were estimated. Urinary levels of free phytoestrogen increased significantly after therapy. They ranged between 0.3–1600, 0.6–670 and 0–206 nmol/L for daidzein, genistein and S-equol, respectively. Monoiodinated derivatives of genistein were observed (0–504 pmol/L) in 60% of the investigated samples. Steroid and thyroid hormone levels were within the normal range and were not significantly altered. The presence of monoiodinated derivates in human urine confirmed that genistein and daidzein may enter human thyroid follicles and influence TPO. Since the levels of the free thyroid hormones were not affected, we propose that the use of phytoestrogen dietary supplements is not associated with the development of thyroid-gland disorders in subjects with adequate iodine intake.  相似文献   
92.
捷克作为欧洲内陆的议会共和制国家,实施强制保险模式以保障民众健康。导致人口死亡的主要疾病为缺血性心脏病、脑卒中和肺癌,而糖尿病、AD及COPD近年来发病率显著增加。捷克的传统医学包括巴赫花疗法、特异性免疫调节自我疗法、法国耳针治疗等。中医药在捷克具有一定的接受度,尤其是针灸已在神经性疾病中得到广泛应用。但中草药在捷克的使用受到限制,且中医药执业尚未合法化。建议深化多层次、多领域交流合作,并通过加强高水平中医药学位教育,加大中药与非药物疗法宣传和普及力度,推动中医药在捷克的发展。  相似文献   
93.
Natural cell-mediated immunity against autologous tumor cells, autologous endometrial epithelium, and allogeneic epidermoid carcinoma cell line HeLa was tested in 8 patients with endometrial carcinoma and one patient with endometrial stromal sarcoma. The average cytotoxicity of unstimulated peripheral blood lymphocytes against autologous tumor and HeLa cells was weak but significant. Pretreatment of effector cells for 3-5 days with 300 U/ml recombinant interleukin-2 (rIL-2) resulted in increased cytotoxicity against malignant target cells in 7 out of 9 cases. The 2 patients' effector cells which were refractory to rIL-2 could be stimulated to appreciable lytic activity against the malignant target cells with a recently described cytokine which induces morphological differentiation of natural killer cells. Benign endometrial cells were weakly sensitive to rIL-2-activated lysis in 2 cases. The precursors of the rIL-2-activated killer cells were mostly CD16-positive and CD3-negative, and co-sedimented with endogenous natural killer cells in discontinuous density gradient centrifugations. These results indicate the rIL-2-activated killer cells have a capacity to distinguish between normal and malignant endometrial cells, and that the precursors of the lytic cells in this system belong to the same subpopulation of lymphocytes as endogenous natural killer cells. In addition, rIL-2 alone may not in all cases be sufficient for optimal generation of cytotoxicity against malignant cells.  相似文献   
94.
Although the chromosome 18 alpha-satellite probe is considered to have a very low polymorphism rate, the routine use of this probe in prenatal diagnosis revealed rare variants in size and copy number of these sequences. A polymorphic signal was detected in preimplantation genetic diagnosis (PGD) for aneuploidy, in a patient with repeated early miscarriages. A third small signal of chromosome 18 alpha-satellite probe was observed in two of four evaluated embryos. Hybridization to the woman's metaphasic lymphocytes revealed that the small signal was localized in the pericentromeric region of chromosome 1. Reanalysis of blastomeres with telomeric probes for chromosome 18q confirmed the presence of only two copies of chromosome 18. Options for verifying PGD analysis results, to prevent misdiagnosis in cases of suspected polymorphism, are discussed. Although some authors speculate about a possible role of heterochromatin polymorphism in infertility, this rare polymorphism of 18 alpha-satellite sequences is in itself probably a normal variant. This is the third report of a cross-hybridization of the chromosome 18 alpha-satellite probe and the first report of the localization of the polymorphic 18 alpha-satellite signal to chromosome 1.  相似文献   
95.
Many pregnancies are lost during early gestation, but clinicians still lack tools to recognize risk factors for miscarriage. Thus, the identification of risk factors for miscarriage during the first trimester in women with no obvious risk for a pregnancy loss was the aim of this prospective cohort trial. A total of 1098 women between gestation weeks 4 and 12 in whom no apparent signs of a threatened pregnancy could be diagnosed were recruited. Demographic, anamnestic, psychometric and biological data were documented at recruitment and pregnancy outcomes were registered subsequently. Among the cases with sufficiently available data, 809 successfully progressing pregnancies and 55 subsequent miscarriages were reported. In this cohort, risk of miscarriage was significantly increased in women at higher age (>33 years), lower body mass index (< or =20 kg/ m(2)) and lower serum progesterone concentrations (< or =12 ng/ml) prior to the onset of the miscarriage. Women with subsequent miscarriage also perceived higher levels of stress/demands (supported by higher concentrations of corticotrophin-releasing hormone) and revealed reduced concentrations of progesterone-induced blocking factor. These risk factors were even more pronounced in the subcohort of women (n = 335) recruited between gestation weeks 4 and 7. The identification of these risk factors and development of an interaction model of these factors, as introduced in this article, will help clinicians to recognize pregnant women who require extra monitoring and who might benefit from therapeutic interventions such as progestogen supplementation, especially during the first weeks of pregnancy, to prevent a miscarriage.  相似文献   
96.
97.
98.
99.
100.
Background: Alongside metabolic diseases (esp. obesity), allergic disorders are becoming increasingly prevalent. Since both obesity and allergies are highly impacted by environmental determinants, with this study we assessed the potential link between metabolic implications and two distinct types of allergies. Methods: Using cross-sectional data from the German FoCus cohort, n = 385 allergy cases, either hay fever (=type I allergy, n = 183) or contact allergy (=type IV allergy, n = 202) were compared to age- and sex-matched healthy control subjects (1:1 ratio, in total n = 770) regarding their metabolic phenotype, diet, physical activity, sleep, gut microbial composition, and serum metabolite profile using suitable BMI-adjusted models. Results: Obesity and metabolic alterations were found significantly more prevalent in subjects with allergies. In fact, this relation was more pronounced in contact allergy than hay fever. Subsequent BMI-adjusted analysis reveals particular importance of co-occurring hyperlipidaemia for both allergy types. For contact allergy, we revealed a strong association to the dietary intake of poly-unsaturated fatty acids, particularly α-linolenic acid, as well as the enrichment of the corresponding metabolic pathway. For hay fever, there were no major associations to the diet but to a lower physical activity level, shorter duration of sleep, and an altered gut microbial composition. Finally, genetic predisposition for hyperlipidaemia was associated to both contact allergy and hay fever. Conclusions: Reflected by higher allergy prevalence, our findings indicate an impaired immune response in obesity and hyperlipidaemia, which is differentially regulated in type I and type IV allergies by an unfavourable lifestyle constellation and subsequent microbial and metabolic dysfunctions.  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