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   2086篇
  免费   131篇
  国内免费   9篇
耳鼻咽喉   18篇
儿科学   56篇
妇产科学   32篇
基础医学   307篇
口腔科学   64篇
临床医学   156篇
内科学   528篇
皮肤病学   45篇
神经病学   141篇
特种医学   69篇
外科学   185篇
综合类   5篇
一般理论   1篇
预防医学   117篇
眼科学   54篇
药学   210篇
中国医学   2篇
肿瘤学   236篇
  2023年   16篇
  2022年   33篇
  2021年   66篇
  2020年   37篇
  2019年   44篇
  2018年   52篇
  2017年   31篇
  2016年   34篇
  2015年   70篇
  2014年   61篇
  2013年   90篇
  2012年   170篇
  2011年   151篇
  2010年   89篇
  2009年   72篇
  2008年   145篇
  2007年   173篇
  2006年   167篇
  2005年   142篇
  2004年   127篇
  2003年   132篇
  2002年   99篇
  2001年   21篇
  2000年   14篇
  1999年   25篇
  1998年   29篇
  1997年   16篇
  1996年   14篇
  1995年   18篇
  1994年   16篇
  1993年   14篇
  1992年   12篇
  1991年   7篇
  1990年   6篇
  1989年   6篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   5篇
  1980年   2篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1962年   1篇
排序方式: 共有2226条查询结果,搜索用时 15 毫秒
991.
992.
The development of nerve-sparing procedures is important in preventing bladder dysfunction following radical hysterectomy. In this study, we dissected 14 halves of 7 female pelvises (age range: 46-86 years; mean age: 74 years) to examine the origins, courses, and distributions of nerve branches to the bladder in females in detail, and 6 halves of 3 male pelvises (age range: 71-85 years, mean age: 78 years) to compare with the female specimens. Nerve branches to the bladder originated mainly from the inferior hypogastric plexus, but independent direct branches running along the ureter from the hypogastric nerve were also distributed particularly to the trigone in all female specimens. We classified these independent branches into four types according to their relationship to the ureter. In males the numbers of the independent branches were small and they were difficult to find. The present observations indicate that nerve distribution patterns to the bladder differ between females and males. In nerve sparing procedures for radical hysterectomy, the area between the ureter and the hypogastric nerve is important.  相似文献   
993.
The cytotoxic effect of eugenol on the expression of molecular markers related to the osteogenic differentiation of human dental pulp cells such as collagen synthesis and the expression of two osteogenesis-related genes, alkaline phosphatase (ALP) and bone sialoprotein (BSP), was studied using human dental pulp cells (D824 cells). Cellular growth and survival were decreased by treatment of cells with eugenol in a concentration-dependent manner. The incorporation rate of [3H] proline into the acid-insoluble fraction and the synthesis of type I–V collagens were also reduced by treatment of cells with eugenol in a concentration-dependent fashion. The mRNA expression of ALP was scarcely affected in cells exposed to eugenol, whereas the mRNA and protein expression of BSP was down-regulated depending on the concentrations of eugenol. The results suggest that because collagen synthesis and BSP expression play a critical role in hard tissue formation, eugenol used for endodontic treatment may give rise to cytotoxic effects to the normal function of stem cells reported to exist in human dental pulp tissue and periodontal ligament.  相似文献   
994.
995.
ObjectiveSodium butyrate (butyric acid; BA) is a major metabolic by-product of the anaerobic periodontopathic bacteria present in subgingival plaque. We examined the effects of BA and/or indomethacin on cell proliferation, the expression of cyclooxygenases (COXs), prostaglandin (PG) receptors (EP1-4), extracellular matrix proteins, such as type I collagen and osteopontin, and PGE2 production, using ROS17/2.8 cells as osteoblasts.MethodsThe rat clonal cell line ROS 17/2.8 was cultured with 0, 10?5, 10?4, and 10?3 M BA in the presence or absence of 0.5 μM indomethacin, for up to 7 days. The expression of COX-1, COX-2, EP1, EP2, EP3, EP4, type I collagen, and osteopontin was examined at the mRNA and protein levels using real-time PCR and Western blotting, respectively. The amount of PGE2 in the culture medium was measured by ELISA.ResultsProliferation of ROS 17/2.8 cells was not affected by the addition of BA. However, PGE2 production and the expression of COX-1 and COX-2 increased with the addition of BA. In contrast, indomethacin, an inhibitor of COX, blocked the stimulatory effect of BA. Furthermore, EP2 expression increased with BA treatment, whereas EP1 expression was not affected and the expression of EP3 and EP4 was not detected. The addition of BA also increased the expression of type I collagen and osteopontin. Indomethacin blocked about 50% of the stimulatory effect of BA on type I collagen, whereas it did not block the effect on osteopontin.ConclusionsThese results suggest that BA induces PGE2 production by increasing the expression of COX-1 and COX-2 in osteoblasts, and that an autocrine action of the produced PGE2, via EP1 or BA-induced EP2, is related to an increase in type I collagen expression by BA.  相似文献   
996.
997.
998.
The purpose of this study on the involvement of epigenetic control of the expression of solute carrier (SLC) transporters by DNA methylation and histone deacetylation in 4 colon cancer cells is to find the epigenetic control mechanisms of drug transporters in colon cancers. Human colon cancer cell lines (HCT116, HT29, SW48, SW480) were treated with 5-aza-2'-deoxycytidine (DAC), as a DNA methyltransferase inhibitor, followed by trichostatin A (TSA), as a histone deacetylase inhibitor. The mRNA expression and DNA methylation of several SLC transporters were analyzed by real-time polymerase chain reaction (PCR) and methylation-specific PCR, respectively. Among 12 SLC transporters possessing cytosine-phosphate-guanine (CpG) islands, thiamine transporter 2 (THTR2) (SLC19A3) gene showed a correlation between its mRNA expression level and DNA methylation status. TSA treatment increased histone H3 acetylation of THTR2 promoter region in all 4 colon cancer cell lines examined. HCT116 and SW48 cells showed a lack of THTR2 mRNA expression and methylation of its promoter, and DAC treatment induced its re-expression. In addition, the co-treatment with DAC and TSA increased THTR2 mRNA expression more markedly than DAC treatment in HCT116 and SW48 cells. In HT29 and SW480 cells that showed little methylation of THTR2 promoter, TSA treatment induced THTR2 mRNA expression markedly, but DAC treatment did not. In the 4 colon cancer cells examined, THTR2 mRNA expression is down-regulated by DNA methylation and/or histone deacetylation.  相似文献   
999.

Background  

Natural killer (NK) cells play an important role in immune responses to virus infection. The cell population consists of CD56bright (bright-subset) and CD56dim (dim-subset) subsets that possess armed functions of cytokine production and cytolysis, respectively. How these subsets are involved in chronic hepatitis C virus infection (CHC) remains obscure.  相似文献   
1000.

Purpose

To date, there is no consensus on the detailed anatomy of the posterior cruciate ligament (PCL) and the most appropriate PCL reconstruction method. The purpose of this study is the detailed observation of separate small PCL bundles for better comprehension of detailed PCL anatomy to facilitate the design of anatomic PCL reconstruction.

Methods

Twelve cadaveric knees were used in this study. PCL was divided into anterolateral and posteromedial (PM) sections and then separated into about 20 small bundles of 1 mm in diameter while maintaining preservation of their attachment sites marked with fine coloured marker pens. The positional relationship between the femoral and tibial attachments of each small bundle was investigated.

Results

The small bundles of tibial and femoral attachments showed a topographical correlation. The anterior–posterior aligned bundles in the tibia corresponded to the bundles aligned in a low–high direction in flexion in the femur. The femoral attachment pattern was relatively similar in each specimen. However, the tibial attachment showed two patterns of small bundle footprint location: a parabolic type (6 of 12) and a transverse type (6 of 12). The posterior portion of the PM bundle was separately attached to the medial and lateral portions in the tibial attachment.

Conclusion

Small bundles of PCL showed a relatively layered arrangement between tibial and femoral attachments. Therefore, anatomic PCL reconstruction cannot be completed simply performed merely with straight bundles and circular bone tunnels.  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