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   2172篇
  免费   144篇
  国内免费   11篇
耳鼻咽喉   10篇
儿科学   49篇
妇产科学   31篇
基础医学   295篇
口腔科学   79篇
临床医学   118篇
内科学   670篇
皮肤病学   77篇
神经病学   170篇
特种医学   57篇
外科学   218篇
综合类   15篇
预防医学   86篇
眼科学   51篇
药学   164篇
中国医学   24篇
肿瘤学   213篇
  2023年   22篇
  2022年   44篇
  2021年   85篇
  2020年   27篇
  2019年   52篇
  2018年   70篇
  2017年   33篇
  2016年   51篇
  2015年   63篇
  2014年   66篇
  2013年   95篇
  2012年   123篇
  2011年   175篇
  2010年   89篇
  2009年   74篇
  2008年   99篇
  2007年   127篇
  2006年   110篇
  2005年   119篇
  2004年   115篇
  2003年   85篇
  2002年   83篇
  2001年   31篇
  2000年   39篇
  1999年   33篇
  1998年   20篇
  1997年   34篇
  1996年   26篇
  1995年   24篇
  1994年   21篇
  1993年   20篇
  1992年   43篇
  1991年   23篇
  1990年   19篇
  1989年   16篇
  1988年   18篇
  1987年   24篇
  1986年   21篇
  1985年   12篇
  1984年   9篇
  1982年   7篇
  1980年   5篇
  1979年   11篇
  1977年   5篇
  1973年   4篇
  1972年   4篇
  1971年   6篇
  1970年   6篇
  1966年   7篇
  1965年   5篇
排序方式: 共有2327条查询结果,搜索用时 187 毫秒
1.
Adolescence is a vulnerable period for developing anxiety-related mental disorders such as post-traumatic stress disorder (PTSD), which requires a long-term course of therapy when a traumatic event has been experienced during childhood. However, the biological mechanism underlying these age-dependent characteristics remains unclear. In the present study, we used early adolescent, late adolescent and adult (4-, 8-, and 15-week old) male mice to examine age differences in fear memory, fear extinction, and spontaneous recovery of fear. We also measured the activation of extracellular signal-regulated kinase (ERK) 2 in the dorsal hippocampus (dHip) and the basolateral amygdala (BLA) following a spontaneous recovery test. Our major findings were as follows: (1) early adolescent and adult mice did not recover the fear response; only late adolescent mice recovered the fear response. (2) The ERK2 in the dHip was more activated after the spontaneous recovery test in late adolescent mice than in adult mice, and the ERK2 in the BLA was more activated after the spontaneous recovery test in adult mice than in late adolescent mice. These results suggest that there exists a unique period in which spontaneous recovery occurs and that these late adolescent behavioral signatures may be related to alteration in the ERK2 phosphorylation in the dHip and BLA.  相似文献   
2.
Hidroacanthoma simplex (HAS) is a rare benign eccrine adnexal tumor. HAS is sometimes clinically or pathologically misdiagnosed as squamous cell carcinoma in situ (Bowen's disease; BD), seborrheic keratosis (SK) or other adnexal tumor. To date, there has never been a report focusing on dermoscopic features to distinguish HAS from BD and SK. We found the following dermoscopic findings to be characteristic of HAS: fine black dots/globules (75% of cases) and fine scales arranged annularly (100% of cases). In contrast, glomerular vessels, which are typically observed in BD, were not seen in any of the four cases. Cerebriform appearance and milia‐like cysts, which are typically observed in SK, were also not seen in any of the four cases. The existence of “scattered fine black dots/globules” and “fine scales arranged annularly”, and the absence of the glomerular vessels, may contribute to precise diagnosis of HAS. Even though HAS resembles BD or SK clinically, it can be distinguished from these by the characteristic dermoscopic features.  相似文献   
3.
Mutations in the gene encoding 11beta-hydroxysteroid dehydrogenase type 2, HSD11B2, cause a rare monogenic juvenile hypertensive syndrome called apparent mineralocorticoid excess (AME). In AME, defective HSD11B2 enzyme activity results in overstimulation of the mineralocorticoid receptor (MR) by cortisol, causing sodium retention, hypokalemia, and salt-dependent hypertension. Here, we have studied whether genetic variations in HDS11B2 are implicated in essential hypertension in Japanese hypertensives and the general population. By sequencing the entire coding region and the promoter region of HDS11B2 in 953 Japanese hypertensives, we identified five missense mutations in 11 patients (L14F, n = 5; R74H, n = 1; R147H, n = 3; T156I, n = 1; R335H, n = 1) and one novel frameshift mutation (4884Gdel, n = 1) in a heterozygous state, in addition to 19 genetic variations. All genetic variations identified were rare, with minor allele frequencies less than 0.005. Four of 12 patients with the missense/frameshift mutations showed renal failure. Four missense mutations, L14F, R74H, R147H, and R335H, were successfully genotyped in the general population, with a sample size of 3,655 individuals (2,175 normotensives and 1,480 hypertensives). Mutations L14F, R74H, R147H, and R335H were identified in hypertensives (n = 6, 8, 3, and 0, respectively) and normotensives (n = 8, 12, 5, and 0, respectively) with a similar frequency, suggesting that these missense mutations may not strongly affect the etiology of essential hypertension. Since the allele frequency of all of the genetic variations identified in this study was rare, an association study was not conducted. Taken together, our results indicate that missense mutations in HSD11B2 do not substantially contribute to essential hypertension in Japanese.  相似文献   
4.
A 34-year-old woman was admitted with an abnormal shadow on a chest X-ray film. Under a preoperative diagnosis of benign bronchogenic cyst, operation was carried out and the tumor was found to be originating from the right main vagal nerve in the mid-superior mediastinum. The vagal nerve was transected to remove the tumor. Pathological diagnosis was a neurinoma. Postoperative complication was chylothorax which was successfully treated with thoracic drainage and intravenous hyperalimentation.  相似文献   
5.
We previously selected a group of hypertension candidate genes by a key word search using the OMIM database of NCBI and validated 525 coding single nucleotide polymorphisms (SNPs) in 179 hypertension candidate genes by DNA sequencing in a Japanese population. In the present study, we examined the association between 61 non-synonymous SNPs and blood pressure variations and hypertension. We used DNA samples taken from 1,880 subjects in the Suita study, a population-based study using randomly selected subjects. Analyses of covariance adjusting for age, body mass index, hyperlipidemia, diabetes, smoking, drinking, and antihypertensive medication revealed that 17 polymorphisms in 16 genes (APOB, CAST, CLCNKB, CTNS, GHR, GYS1, HF1, IKBKAP, KCNJ11, LIPC, LPL, P2RY2, PON2, SLC4A1, TRH, VWF) were significantly associated with blood pressure variations. Multivariate logistic regression analysis with adjustment for the same factors revealed that 11 polymorphisms in 11 genes (CAST, CTLA4, F5, GC, GHR, LIPC, PLA2G7, SLC4A1, SLCI8A1, TRH, VWF) showed significant associations with hypertension. Five polymorphisms in five genes, CAST(calpastatin), LIPC (hepatic lipase), SLC4A1 (band 3 anion transporter), TRH (thyrotropin-releasing hormone), and VWF (von Willebrand factor), were significantly associated with both blood pressure variation and hypertension. Thus, our study suggests that these five genes were susceptibility genes for essential hypertension in this Japanese population.  相似文献   
6.
We report a case diagnosed as bilateral ureteritis cystica by ureteroscopic examination. A 51-year-old female was admitted with pyuria and proteinuria. Retrograde pyelography revealed multiple, small, smooth and round punched-out defects in the bilateral lower ureters. Ureteroscopic examination and punch biopsy were performed with a suspected diagnosis of ureteritis cystica. The histological examination revealed chronic ureteritis. This patient was given conservative treatment (chemotherapy) and careful follow-up.  相似文献   
7.
8.
9.
In human testis, expression of a novel member of the aldo-keto reductase family was identified. Based on its testis-specific expression, we termed this protein human testis aldo-keto reductase (htAKR). In addition to four major isoforms, the existence of multiple alternatively spliced products of htAKR was detected using RT-PCR followed by nested PCR. htAKR was a homologue of mouse liver keto-reductase, AKR1E1, with close similarity in their genomic organizations. htAKR4, the longest isoform, was expressed as a non-fused native form. It exhibited a limited activity toward 9,10-phenanthrenequinone, while no activity toward the steroids or prostaglandins was demonstrated. Using the laser capture microdissection technique and RT-PCR, expression of htAKR was detected in testicular germ cells as well as in interstitial cells. The levels of htAKR mRNA in the tissues obtained from seminoma were much lower than those in normal testes. A significant decline in the htAKR expression was observed when NEC8, a cell line originated from a human testicular germ cell tumour, was exposed to phorbol 12-myristate 13-acetate or 5alpha-dihydrotestosterone. These results indicate that the expression of htAKR, down-regulated in the testicular tumour, is possibly controlled by mitogenic and hormonal signals.  相似文献   
10.
The cellular localization of Babesia bovis rhoptry-associated protein 1 (RAP-1) and its erythrocyte-binding affinity were examined with anti-RAP-1 antibodies. In an indirect immunofluorescent antibody test, RAP-1 was detectable in all developmental stages of merozoites and in extracellular merozoites. In the early stage of merozoite development, RAP-1 appears as a dense accumulation, which later thins out and blankets the host cell cytoplasm, but retains a denser mass around newly formed parasite nuclei. The preferential accumulations of RAP-1 on the inner surface of a host cell membrane and bordering the parasite's outer surface were demonstrable by immunoelectron microscopy. An erythrocyte-binding assay with the lysate of merozoites demonstrated RAP-1 binding to both bovine and equine erythrocytes. Anti-RAP-1 monoclonal antibody 1C1 prevented the interaction of RAP-1 with bovine erythrocytes and significantly inhibited parasite proliferation in vitro. With the recombinant RAP-1, the addition of increasing concentrations of Ca(2+) accentuated its binding affinity with bovine erythrocytes. The present findings lend support to an earlier proposition of an erythrocytic binding role for RAP-1 expressed in B. bovis merozoites and, possibly, its involvement in the escape of newly formed merozoites from host cells.  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