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   5949篇
  免费   394篇
  国内免费   31篇
耳鼻咽喉   60篇
儿科学   165篇
妇产科学   131篇
基础医学   719篇
口腔科学   209篇
临床医学   440篇
内科学   1365篇
皮肤病学   136篇
神经病学   263篇
特种医学   101篇
外国民族医学   4篇
外科学   957篇
综合类   198篇
一般理论   2篇
预防医学   474篇
眼科学   124篇
药学   598篇
中国医学   82篇
肿瘤学   346篇
  2023年   90篇
  2022年   42篇
  2021年   251篇
  2020年   205篇
  2019年   248篇
  2018年   237篇
  2017年   189篇
  2016年   221篇
  2015年   239篇
  2014年   291篇
  2013年   347篇
  2012年   524篇
  2011年   549篇
  2010年   286篇
  2009年   242篇
  2008年   387篇
  2007年   289篇
  2006年   292篇
  2005年   281篇
  2004年   221篇
  2003年   188篇
  2002年   192篇
  2001年   40篇
  2000年   51篇
  1999年   53篇
  1998年   31篇
  1997年   25篇
  1996年   21篇
  1995年   27篇
  1994年   25篇
  1993年   22篇
  1992年   21篇
  1991年   10篇
  1990年   20篇
  1989年   22篇
  1988年   19篇
  1987年   24篇
  1986年   14篇
  1985年   6篇
  1984年   8篇
  1983年   16篇
  1982年   15篇
  1981年   11篇
  1980年   7篇
  1979年   5篇
  1977年   9篇
  1975年   6篇
  1974年   7篇
  1973年   7篇
  1971年   5篇
排序方式: 共有6374条查询结果,搜索用时 171 毫秒
1.
Objective: To study the effectiveness of the smoking prevention module towards knowledge on smoking and its harmful effects and smoking refusal skills among secondary school students in Kelantan, Malaysia. Methods: A quasi experimental interventional study involving 166 non-smokers adolescents, aged 13 to 14 years old were carried out in two schools located in two different suburbs. Both schools had equal number of participants. One school was given the smoking prevention module for intervention while the control school only received the module after the study had been completed. The knowledge on smoking and its harmful effects and smoking refusal skill score were assessed using a set of validated Malay questionnaires at baseline, two weeks and eight weeks after the intervention. Repeated measure ANCOVA was used to analyse the mean score difference of both groups at baseline and after intervention. Result: Baseline analysis shows no significant difference in knowledge score between the study groups (p = 0.713) while post intervention, it shows significant inclination of knowledge score in intervention group and the difference was significant after controlling the gender [F(df) = 15.96(1.5), p <0.001]. The mean baseline for refusal skills score in the control and intervention groups were 30.89(6.164) and 28.02(6.241) respectively (p= 0.003). Post intervention, there is a significant difference in the crude mean and the estimated marginal means for smoking refusal skills score between the two groups after controlling for sex [F(df) = 5.66(1.8), p = 0.005]. Conclusion: This smoking prevention module increased the level of knowledge on smoking and its harmful effects and smoking refusal skill among the secondary school students. Thus, it is advocated to be used as one of the standard modules to improve the current method of teaching in delivering knowledge related to harmful effects of smoking and smoking refusal skill to the adolescents in Malaysia.  相似文献   
2.
Tick‐borne diseases (TBDs) have a large impact on animal health and the livelihood of livestock owners, particularly in developing countries. Although climatic and ecological conditions in Pakistan may favour the transmission of tick‐borne pathogens (TBPs), only a few systematic studies have been carried out on TBPs and the diseases that they cause in this country. To improve our understanding of the distribution of TBPs, 3,807 ticks were collected from ruminants (n = 369) on 108 livestock farms (semi‐arid zone = 36, arid zone = 72) in Punjab Province. After morphological identification ticks were pooled into 405 pools (Hyalomma anatolicum = 300, Rhipicephalus microplus = 89, Hyalomma dromedarii = 9, Rhipicephalus turanicus = 7) based on their species, locality of collection, and the host. DNA from each pool was screened by a Reverse Line Blot (RLB) hybridization assay for the presence of Anaplasma, Ehrlichia, Rickettsia, Babesia, and Theileria species. DNA from at least one TBP was found in 142 (35.1%) pools. Among the positive pools, 91 (64.1%) had a mixed infection with two or more TBPs, whereas 51 (35.9%) pools were infected with a single TBP. The detected pathogens not only included species that were known to be endemic in Pakistan, such as Theileria annulata (6.7%), Theileria orientalis (3.5%), Anaplasma marginale (5.7%), Anaplasma centrale (2.7%), Anaplasma ovis (1.5%), Babesia bigemina (0.7%), and Babesia bovis (0.2%), but also several TBPs that had not been reported to occur in Pakistan before. This included Ehrlichia minasensis (3.2%), an Anaplasma platys‐like organism (1.2%), Babesia occultans (0.2%), and Rickettsia massiliae (0.2%), as well as two previously uncharacterized species: Ehrlichia sp. Multan (18.0%) and Anaplasma sp. (BL099‐6) (2.22%). The pathogenicity of these novel species remains to be examined. This study shows that a much broader spectrum of TBPs is present in Pakistan than previously thought, including several zoonotic pathogens.  相似文献   
3.
The aim of the present study was to determine the protective effects of pomegranate juice in tris‐based extender on semen parameters, computer‐assisted sperm analysis (CASA) motion characteristics and field fertility of post‐thawed Nili Ravi buffalo (Bubalus bubalis) bull spermatozoa. Two consecutive ejaculates/collection from each of the five adult Nili Ravi buffalo bulls were collected with artificial vagina at 42°C for a period of 7 weeks, diluted in extender containing different concentrations of pomegranate juice (0.0%, 2.5%, 5%, 7.5% and 10%). Diluted samples were packed and frozen in 0.54 ml French straws. The addition of 10% pomegranate juice in extender significantly improved post‐thaw sperm morphology (%), motilities (CASA total motility, progressive motility (%) as well as VAP, VSL, VCL, STR, DAP, DSL) compared to the control group (p < 0.05). Plasma membrane, acrosome membrane and DNA integrity were significantly higher in extender with 10% pomegranate juice than the control group (p < 0.05). Field fertility rate (60.39% vs. 46.53%) was higher (p < 0.05) in extender with 10% pomegranate juice as compared to the control. It is therefore concluded that the addition of 10% pomegranate juice in tris‐based extender improves post‐thaw semen parameters, CASA motion dynamics and field fertility in Nili Ravi buffaloes.  相似文献   
4.
5.
全世界每年有超过2 000万台腹股沟疝手术。为了进一步标准化、减少并发症、改善手术结果,5个洲际疝协会(欧洲疝协会、美国疝协会、亚太疝协会、非洲中东疝协会、澳洲疝协会)、国际内镜疝协会以及欧洲内镜外科协会共同签署发布了腹股沟疝治疗国际指南(2018版)。笔者重点对其中有关日间手术的部分进行详细解读。  相似文献   
6.
7.
8.
Malignant melanoma is notorious for its remarkable morphological variation and aberrant histopathological patterns. However, melanoma with prominent cartilaginous transdifferentiation simulating chondrosarcoma is extremely rare. A 75‐year‐old male developed a swelling in his left inguinal region and was diagnosed with a metastatic melanoma, which was found to harbor a BRAF V600E mutation. Later on, the left inguinal lymph node was excised and immunohistochemistry done on the specimen revealed an undifferentiated component negative for S‐100 protein, HMB‐45 and Melan‐A and a cartilaginous component positive for S‐100 protein and diffusely positive for BRAF V600E mutation. To our knowledge, there are around 14 cases reported in the literature of malignant melanoma with pure cartilaginous transdifferentiation. In all cases, immunohistochemistry of the cartilaginous component was positive for S‐100, which is not an indicator of melanoma because cartilage expresses S‐100. BRAF mutational studies support that the tumor arose from a common melanoma cell that harbored the mutation and subsequently transdifferentiated. This case illustrates the importance of an accurate and thorough clinical assessment when it comes to the diagnosis of melanomas as they are notable for their impressive degree of morphologic variability. Moreover, this report helps shed light on the use of immunohistochemical analysis to reach a definitive diagnosis.  相似文献   
9.
10.
Objective: To analyze the effect of sirolimus and sunitinib in blocking the tumor growth and to evaluate the expressions of estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor-2 (HER2/neu) after treated with sirolimus and sunitinib. Methods: Thirty-two female Sprague Dawley rats at age 21-days old were administered intraperitoneally with N-Methyl-N-Nitroso Urea (NMU), dosed at 70mg/kg body weight. The rats were divided into 4 groups; Group 1 (Control, n=8), Group 2 (Sirolimus, n=8), Group 3 (Sunitinib, n=8) and Group 4 (Sirolimus+Sunitinib, n=8), being treated twice when the tumor reached the size of 14.5±0.5 mm and subsequently sacrificed after 5 days. The protein expressions of ER, PgR and HER2/neu of the tumor tissues were evaluated by using immunohistochemistry analysis. Results: Treatment with sirolimus alone lowered expressions of ER and PgR of breast cancer and reduced tumor size. There was no significant difference of ER and PgR expressions between control and sunitinib treated tumor. Sunitinib treated tumors reduce in diameter after the first treatment, however the diameter increases after the second treatment. Histologically, sunitinib treated tumor did not show any aggressive invasive carcinoma of no special type (NST) histological subtypes. In addition, all NMU-induced tumors are HER2/neu-negative scoring. Conclusion: Sirolimus is neither synergistic nor additive with sunitinib for breast cancer treatment.  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