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   914篇
  免费   64篇
  国内免费   109篇
  2024年   1篇
  2023年   29篇
  2022年   53篇
  2021年   26篇
  2020年   35篇
  2019年   42篇
  2018年   29篇
  2017年   32篇
  2016年   50篇
  2015年   70篇
  2014年   101篇
  2013年   131篇
  2012年   63篇
  2011年   79篇
  2010年   34篇
  2009年   19篇
  2008年   31篇
  2007年   33篇
  2006年   22篇
  2005年   18篇
  2004年   20篇
  2003年   13篇
  2002年   19篇
  2001年   11篇
  2000年   11篇
  1999年   11篇
  1998年   9篇
  1997年   7篇
  1996年   4篇
  1995年   4篇
  1994年   6篇
  1993年   29篇
  1992年   7篇
  1991年   3篇
  1990年   7篇
  1989年   4篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   7篇
  1979年   1篇
  1977年   2篇
  1973年   3篇
排序方式: 共有1087条查询结果,搜索用时 15 毫秒
981.
AmisHashimoto’s thyroiditis (HT) is the most common type of autoimmune thyroiditis and is a risk factor for the occurrence of thyroid papillary carcinoma (PTC). The study aimed to explore the distribution of CARD9 rs4077515 polymorphism in HT and PTC patients, in order to evaluate its association with the occurrence and development of HT.Methods150 HT patients and 120 PTC cases were included. Genotypes of CARD9 rs40775155 polymorphism were sequenced and counted.ResultsA remarkable increase trend of rs4077515 AA genotype was found in HT cases in comparison with the control group, while GG genotype frequency exhibited a down trend. An excess of A allele was also detected in HT group. HT cases carrying AG and AA genotypes had high risk to receive hormonotherapy and needed a much larger dose. In comparison with HT cases, both AG and AA appeared more frequently in PTC patients, and are associated with the tumor size, LN metastasis and surgical margin. The AG (OR = 2.566, 95 % CI = 1.376–4.786) and AA (OR = 3.040, 95 % CI = 1.525–6.060) genotype carriers had a greater risk of developing PTC. The A allele of rs4077515 polymorphism was a risk allele for the onset of PTC among HT cases (OR = 1.775, 95 % CI = 1.260–2.502).ConclusionCARD9 rs4077515 polymorphism is likely to be a risk factor for HT in the Chinese Han population, it also contributes to the development of PTC for HT patients.  相似文献   
982.
983.
984.
Two species of the pompilid genus Agenioideus occurring in Japan are described: A . ( Agenioideus ) kokyo and A . ( A .) cinctellus . The former is new to science and the latter is recorded from Japan and Taiwan for the first time. A brief summary of the biology of A. cinctellus , distinguishing characters between A. ( A. ) ishikawai Shimizu, 1989 and its relatives, and a key to all Japanese species of this genus are presented. Psammochares cinctellus f. rufa Haupt, 1938 and A . ( A. ) pacificus Lelej, 1994 are newly synonymized with A. cinctellus . A new combination is proposed: A . ( A .) maculipes (Smith, 1870) (= Pompilus maculipes Smith), which is found in Southeast Asia to South Asia. Agenioideus ishikawai is newly recorded from Korea and China.  相似文献   
985.
Since the "seed and soil" hypothesis was proposed, the biological functions of the tumor microenvironment (TME), especially its stromal components, have received increasing attention. Cancer-associated fibroblasts (CAFs) are the major components of the stromal region, providing material support for tumor cell proliferation, migration, and invasion. Furthermore, CAFs are important mediators of suppressing immune responses by attracting the accumulation of immunosuppressive cells through cytokine/chemokine secretion. In this review, we summarized the major cytokines, chemokines and metabolites, including transforming growth factor-β (TGF-β), interleukin-6 (IL-6), C-X-C chemokine ligand (CXCL)12, C–C chemokine ligand (CCL) 2, prostaglandin E2 (PGE2), and other factors, by which CAFs suppress the immune systems in a variety of cancers. More importantly, we highlight potential therapeutic strategies to alleviate the immunosuppression produced by CAFs, thereby inhibiting tumor progression.  相似文献   
986.
987.
Quantitative analysis of the trace element content of human intervertebral discs (IVDs) is essential because it can identify specific enzymes or metabolites that may be related to human intervertebral disc degeneration (IVDD). The goal of this study was to assess the concentrations of copper (Cu), iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), sodium (Na), magnesium (Mg), potassium (K), phosphorus (P), and calcium (Ca) in serum samples obtained from patients with IVDD in comparison to healthy volunteers (a control group). The study group consisted of 113 Caucasian patients qualified by a specialist neurosurgeon for microdiscectomy. The control group consisted of 113 healthy volunteers who met the eligibility criteria for blood donors. The examined clinical material was the serum samples obtained from both groups.Based on the quantitative analysis of selected elements, there were statistically significantly (p 0.05) higher concentrations of Cu (1180 μg/L±800 μg/L vs. 1230 μg/L±750 μg/L), Zn (790 μg/L±300 μg/L vs. 850 μg/L±200 μg/L), and Mg (21730 μg/L±4360 μg/L vs. 23820 μg/L±4990 μg/L) in the serum of healthy volunteers compared to those in the study group. In addition, statistically significant changes were not detected in the concentrations of any elements among either sex in either the study or control group or in their body mass index (BMI) values (p > 0.05). In the serum samples from the study group, the strongest relationships were noted between the concentrations of Zn and Pb (r = 0.61), Zn and P (r = 0.69), Zn and Ca (r = 0.84), Zn and Cu (r = 0.83), Mg and Ca (r = 0.74), and Ca and P (r = 0.98).It has been indicated that, above all, the concentrations of Cu, Zn, Ca, and Mg depend on the advancement of radiological changes, according to the Pfirrmann scale. However, no influence on pain intensity was found, depending on the concentration of the assessed elements.The analysis indicates that the determination of serum Cu, Zn, Ca, and Mg concentrations may have diagnostic significance in predicting the onset of lumbosacral IVDD. The predictive evaluation of changes in the concentrations of selected elements in patients with degenerative lumbar IVD lesions appears to be a promising, cost-effective strategy.  相似文献   
988.
A new synonym in the ant genus Ponera , and a new species-record from Japan are reported following faunal surveys of Yakushima Island, Kagoshima Prefecture. Morphological comparison of type specimens with material collected on Yakushima and mainland Kyushu and Honshu reveals that Ponera yakushimensis Tanaka is a junior synonym of Ponera scabra Wheeler. Analysis of intraspecific variation in P. scabra is reported. Morphological comparison reveals that a recent putative distribution record of P. scabra from Yakushima was based on a misidentification of Ponera alisana Terayama. This is the first Japanese record of P. alisana , which was originally described from Taiwan. Geographic variation between the P. alisana types and specimens collected on Yakushima is discussed. A revised key to Japanese Ponera species is presented.  相似文献   
989.
Summary

Based on the accounts by various authors, an identification key has been constructed for the planktonic zoeae of the 70 species of Mediterranean Brachyura whose larvae are known. The key is based on primary (spines of the carapace, exopodite of the antenna, spines of telson forks) as well as secondary (setation of mouthparts, processes and spines on abdominal somites) morphological characteristics. It allows the identification of the zoeae of 64 species plus those of Liocarcinus genus (six species).  相似文献   
990.
Three new species of Paradiaptomus from southern Africa are described, Paradiaptomus peninsularis, P. hameri and P. warreni. Paradiaptomus peninsularis occurs in temporary blackwater pools on the peninsula of the Western Cape province, P. hameri in saline pools in the Western Cape province and P. warreni in mountain tarns in the Drakensberg Range in Kwazulu Natal and Lesotho. The genus Paradiaptomus was first established by Sars (1895) for Paradiaptomus lamellatus. There are five described species of Paradiaptomus endemic to Africa ( lamellatus, schultzei, similis, natalensis and rex) and P. greeni from India and Sri Lanka. The three new species have highly-weighted morphological characters which set them apart from each other and from any of the described species of Paradiaptomus.  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