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   3540篇
  免费   392篇
  国内免费   11篇
耳鼻咽喉   12篇
儿科学   48篇
妇产科学   84篇
基础医学   383篇
口腔科学   78篇
临床医学   328篇
内科学   1011篇
皮肤病学   45篇
神经病学   478篇
特种医学   114篇
外科学   468篇
综合类   76篇
一般理论   4篇
预防医学   288篇
眼科学   99篇
药学   247篇
中国医学   37篇
肿瘤学   143篇
  2021年   34篇
  2020年   30篇
  2019年   30篇
  2018年   61篇
  2017年   33篇
  2016年   41篇
  2015年   43篇
  2014年   63篇
  2013年   156篇
  2012年   168篇
  2011年   214篇
  2010年   104篇
  2009年   117篇
  2008年   213篇
  2007年   217篇
  2006年   209篇
  2005年   191篇
  2004年   205篇
  2003年   162篇
  2002年   190篇
  2001年   33篇
  2000年   34篇
  1999年   34篇
  1998年   48篇
  1997年   39篇
  1996年   41篇
  1995年   31篇
  1994年   32篇
  1993年   31篇
  1992年   28篇
  1991年   35篇
  1990年   26篇
  1989年   24篇
  1988年   30篇
  1987年   39篇
  1985年   30篇
  1984年   31篇
  1983年   30篇
  1982年   51篇
  1981年   47篇
  1980年   53篇
  1979年   29篇
  1978年   29篇
  1977年   41篇
  1976年   30篇
  1975年   23篇
  1974年   34篇
  1973年   35篇
  1972年   27篇
  1963年   28篇
排序方式: 共有3943条查询结果,搜索用时 31 毫秒
91.
Renal cell carcinoma (RCC) is the most common cancer of the kidney. Cytogenetic studies of renal cell carcinoma have provided valuable insight into the chromosomal abnormalities involved in the genesis and progression of the disease, and have also helped in the classification of these tumors. Our objectives were to identify nonrandom chromosome abnormalities in renal tumors in a Southeast Asian population and also to determine if they differ from those in Western populations. Structural rearrangements of 3p were specific for clear cell RCC, with the most consistent structural rearrangement being a translocation between 3p13 and 5q22. Gains of chromosomes 7 and 17 were observed in three and two cases of papillary RCC, respectively. All male patients with papillary RCC were noted to have loss of the Y chromosome. Gains of chromosomes 3 and 7, and structural aberration of chromosome 3, were observed in patients with transitional cell carcinoma of the renal pelvis (TCC). Chromosomal abnormalities in clear cell RCC, papillary RCC, and TCC did not differ between the Southeast Asian and Western populations. The aberrations seem to be common sporadic events, both geographically and racially.  相似文献   
92.
ERN varies with degree of psychopathy in an emotion discrimination task   总被引:1,自引:0,他引:1  
It is hypothesized that anterior cingulate cortex (ACC) function may be disrupted in psychopathy. Since ACC is considered the generator of the error-related negativity (ERN), we expected the ERN to be sensitive to the degree of psychopathy among violent offenders. EEG was collected while offenders and controls responded to a standard letter flanker task and to a face flanker task that required discrimination between angry and fearful expressions. Offenders were as accurate as controls on the letter flanker task but made more errors in emotion discrimination on the face flanker task. ERNs elicited by letter flanker errors did not differ across groups but were markedly reduced in the offenders in the face flanker condition. These effects were related to the degree of psychopathy within the offender group. Source modelling of the ERN also indicated an atypical response for psychopaths when error monitoring required the discrimination of affectively based information.  相似文献   
93.
The act of eating requires a decision by an animal to place food in its mouth. The reasons to eat are varied and include hunger as well as the food's expected reward value. Previous studies of tastant processing in the rat primary gustatory cortex (GC) have used either anesthetized or awake behaving preparations that yield somewhat different results. Here we have developed a new preparation in which we explore the influences of intra-oral and non-contingent tastant delivery on rats' behavior and on their GC neural responses. We recorded single-unit activity in the rat GC during two sequences of tastant deliveries, PRE and POST, which were separated by a waiting period. Six tastants ranging in hedonic value from sucrose to quinine were delivered in the first two protocols called 4TW and L-S. In the third one, the App L-S protocol, only hedonically positive tastants were used. In the 4TW protocol, tastants were delivered in blocks whereas in the two L-S protocols tastants were randomly interleaved. In the 4TW and L-S protocols the probability of ingesting tastants in the PRE sequence decreased exponentially with the trial number. Moreover, in both protocols this decrease was greater in the POST than in the PRE sequence likely because the subjects learned that unpleasant tastants were to be delivered. In the App L-S protocol the decrease in ingestion was markedly slower than in the other protocols, thus supporting the hypothesis that the decrease in appetitive behavior arises from the non-contingent intra-oral delivery of hedonically negative tastants like quinine. Although neuronal responses in the three protocols displayed similar variability levels, significant differences existed between the protocols in the way the variability was partitioned between chemosensory and non-chemosensory neurons. While in the 4TW and L-S protocols the former population displayed more changes than the latter, in the App L-S protocol variability was homogeneously distributed between the two populations. We posit that these tuning changes arise, at least in part, from compounds released upon ingestion, and also from differences in areas of the oral cavity that are bathed as the animals ingest or reject the tastants.  相似文献   
94.
Research on the reliability of cardiovascular reactivity has focused on temporal stability and intertask consistency with only modest results. The present study evaluated the internal consistency reliability of cardiovascular reactivity in three large samples of adolescents and young adults (N=326, 136, and 142). Impedance cardiographic and blood pressure measures were recorded at rest and during standard laboratory stress tasks (math, video game, cold pressor). The reliability of cardiovascular reactivity within tasks, as assessed by Cronbach's alpha coefficient of internal consistency, ranged from alpha=.83 to .96 for 4-min to 5-min math tasks, and alpha=.65 to .94 for 3-min video game and cold pressor tasks. Although highly reliable within tasks, cardiovascular reactivity was less reliable across tasks, even within a single testing session. Possible reasons for the discrepancy between internal consistency and intertask consistency are discussed.  相似文献   
95.
Intimate partner violence (IPV) may increase as women in patriarchal societies become empowered, implicitly or explicitly challenging prevailing gender norms. Prior evidence suggests an inverse U-shaped relationship between women’s empowerment and IPV, in which violence against women first increases and then decreases as more egalitarian gender norms gradually gain acceptance. By means of focus-group discussions and in-depth interviews with men in 10 Bangladeshi villages, this study explored men’s evolving views of women, gender norms and the legitimacy of men’s perpetration of IPV in the context of a gender transition. It examines men’s often-contradictory narratives about women’s empowerment and concomitant changes in norms of masculinity, and identifies aspects of women’s empowerment that are most likely to provoke a male backlash. Findings suggest that men’s growing acceptance of egalitarian gender norms and their self-reported decreased engagement in IPV are driven largely by pragmatic self-interest: their desire to improve their economic status and fear of negative consequences of IPV.  相似文献   
96.
Gastrocutaneous fistula after gastrostomy tube removal may persist for a prolonged period. We present a case of a 58-year-old woman with a GCF that had persisted for 5 months following the removal of an endoscopically-placed gastrostomy tube (PEG). Conservative therapy with anti-acid medications and administering motility agents was unsuccessful. For the closure of the GCF, the endoscopic metal clips were used to close the fistula.  相似文献   
97.
Rotator cuff tears (RCT) is a multifactorial disease with genetic factors contributing for the disease etiology. We hypothesized that genetic variants in genes involved in extracellular matrix (ECM) homeostasis may alter susceptibility to RCT. We evaluated 20 polymorphisms of genes involved in ECM homeostasis in 211 cases of full-thickness tears of the supraspinatus (Nfemales = 130; Nmales = 81) and 567 age-matched controls (Nfemales = 317; Nmales = 250). Multivariate logistic regressions were carried out with age, gender, genetic ancestry (based on the analysis of 61 biallelic short insertion/deletion polymorphisms), and common co-morbidities (diabetes, dyslipidemia, and smoking habits) as covariates. We observed that carriers of the rare allele of both studied variants of TGFB1, as well as their G/A (rs1800470/rs1800469) haplotype, were less susceptible to RCT (p < 0.05). In contrast, carriers of the G allele of MMP9 rs17576 (p = 0.014) or G/G haplotype (rs17576/rs17577; p < 0.001) had an increased risk for tendon tears. The presence of the T allele of MMP2 rs2285053 (p = 0.033), the T allele of MMP3 rs679620 (p = 0.024), and the TT-genotype of TIMP2 rs2277698 (p = 0.01) was associated with susceptibility to tears, especially in females. In males, the A allele of COL5A1 rs3196378 (p = 0.032) and the G allele of TGFBR1 rs1590 (p = 0.039) were independent risk factors for RCT. The C/T COL5A1 (rs3196378/rs11103544) haplotype was associated with a reduced risk of tears in males (p = 0.03). In conclusion, we identified the genetic variants associated with RCT susceptibility, thereby reinforcing the role of genes involved in the structure and homeostasis of the ECM of tendons in disease development. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:192–201, 2020  相似文献   
98.
We followed a patient with manganese transporter deficiency due to homozygous SLC30A10 mutations from age 14 years until his death at age 38 years and present the first postmortem findings of this disorder. The basal ganglia showed neuronal loss, rhodanine‐positive deposits, astrocytosis, myelin loss, and spongiosis. SLC30A10 protein was reduced in residual basal ganglia neurons. Depigmentation of the substantia nigra and other brainstem nuclei was present. Manganese content of basal ganglia and liver was increased 16‐fold and 9‐fold, respectively. Our study provides a pathological foundation for further investigation of central nervous system toxicity secondary to deregulation of manganese metabolism. Ann Neurol 2014;75:608–612  相似文献   
99.
100.
A patient with combined folate and B12 deficiency due to tropical sprue failed to respond to the administration of N5-methyltetrahydrofolate when given by mouth or intravenously. After the injection of 1 μg of B12 intravenously the patient became asymptomatic and laboratory tests returned to normal. Failure of response to N5-methyltetrahydrofolate in the presence of B12 deficiency is evidence in favor of the “folate trap” hypothesis.  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