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   19135篇
  免费   1577篇
  国内免费   563篇
耳鼻咽喉   169篇
儿科学   304篇
妇产科学   555篇
基础医学   2509篇
口腔科学   403篇
临床医学   2102篇
内科学   3979篇
皮肤病学   233篇
神经病学   1175篇
特种医学   467篇
外国民族医学   3篇
外科学   2616篇
综合类   1466篇
现状与发展   3篇
一般理论   5篇
预防医学   1035篇
眼科学   741篇
药学   1574篇
  6篇
中国医学   569篇
肿瘤学   1361篇
  2024年   17篇
  2023年   208篇
  2022年   236篇
  2021年   681篇
  2020年   449篇
  2019年   484篇
  2018年   568篇
  2017年   504篇
  2016年   492篇
  2015年   663篇
  2014年   803篇
  2013年   924篇
  2012年   1387篇
  2011年   1490篇
  2010年   883篇
  2009年   717篇
  2008年   1088篇
  2007年   1094篇
  2006年   1140篇
  2005年   1114篇
  2004年   918篇
  2003年   785篇
  2002年   771篇
  2001年   538篇
  2000年   529篇
  1999年   481篇
  1998年   187篇
  1997年   192篇
  1996年   159篇
  1995年   113篇
  1994年   110篇
  1993年   76篇
  1992年   206篇
  1991年   188篇
  1990年   165篇
  1989年   146篇
  1988年   117篇
  1987年   111篇
  1986年   91篇
  1985年   62篇
  1984年   43篇
  1983年   31篇
  1982年   45篇
  1981年   39篇
  1980年   35篇
  1979年   36篇
  1978年   32篇
  1977年   19篇
  1975年   20篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
高压交变电磁场对心血管疾病康复的应用   总被引:2,自引:0,他引:2  
陈银海  张育君 《中国康复》1997,12(4):149-151
应用高压交变电磁场对134例冠心病及高血压病患者进行临床应用,结果显效67例,好转55例,无效12例;有效地改善了脂蛋白代谢,降低TG、Tc、LDL-c及致动脉硬化指数.升高HDL-c浓度;降低了高血压病患者的血压;改善了冠心病患者的心电图;同时可改善心功能参数及心室负荷。由此可见,高压交变电磁场能抗动脉粥样硬化,对心血管疾病有显著的治疗作用。  相似文献   
103.
We studied 11 head and neck squamous carcinoma (HNSC) cell lines and 46 primary tumors for p16 gene status by protein, mRNA, and DNA genetic/epigenetic analyses to determine the incidence, the mechanism(s), and the potential biological significance of its inactivation. Of the 11 cell lines, only 1 showed intact p16 and 10 lacked its protein and mRNA; DNA analysis of these 10 cell lines showed 2 homozygous deletions, 6 methylations at exon 1 and 2, and 2 with no detectable abnormalities. In primary tumors, 16 (34.7%) of the 46 showed detectable p16 protein and mRNA; of these, 12 had no DNA abnormalities and 4 had only exon 2 methylation. Loss of p16 expression was found in three tumors with concurrent mutation at exon 2 and methylation at exon 2 (two) and both 1 and 2 (one). Of the 30 tumors that lacked p16 protein, 27 also lacked mRNA, 1 had detectable p16 mRNA, and 2 failed RT-PCR amplification. Twenty-two of the thirty tumors showed DNA alterations and eight manifested no abnormalities; DNA alterations comprised 6 homozygous deletions, 2 concurrent mutations and methylation of exon 2, and 13 with methylation at exon 1 and exons 1 and 2 (12 with methylation only and 1 with mutation) at exon 1. Except for patients' gender (P = 0.02), no significant correlation between p16 and clinicopathological factors was observed. We conclude that in HNSC 1) intragenic p16 alterations are infrequent events, 2) methylation of exon 1 constitutes a common mechanism in silencing the p16 gene, 3) p16 inactivation may play an important role in the early development and progression of HNSC, and 4) no association between p16 alterations and conventional clinicopathological factors was noted in this cohort.  相似文献   
104.
Postoperative deep vein thrombosis in the Taiwanese Chinese population   总被引:1,自引:0,他引:1  
Reports of the incidence of postoperative deep vein thrombosis in the Chinese population of Taiwan are few in the literature. Over a 3 year period, the fibrinogen degradation products test, the pulse volume recorder, and venography were used to study 220 patients undergoing major operations at the Veterans General Hospital in Taipei, Taiwan. Deep vein thrombosis was found in 17 patients (7.7 percent). A comparison of the three diagnostic methods showed that the sensitivities of the fibrinogen degradation products test and the pulse volume recorder were 56.3 percent and 93.7 percent, respectively; the specificities, 97.4 percent and 95.7 percent, respectively; and the accuracies, 85.5 percent and 95.5 percent, respectively. These results support the combined use of the fibrinogen degradation products test and the pulse volume recorder for screening and diagnosing deep vein thrombosis.  相似文献   
105.

Background  

To date, the literature has provided an abundance of evidence on the adverse outcomes of restraint use on patients. Reportedly, nurses are often the personnel who initiate restraint use and attribute its use to ensuring the safety of the restrained and the others. A clinical trial using staff education and administrative input as the key components of a restraint reduction program was conducted in a rehabilitation setting to examine whether there were any significant differences in the prevalence of restraint use pre- and post-intervention. Subsequent to the implementation of the intervention program, focus group interviews were conducted to determine the perspective of the nursing staff on the use of restraints and their opinions of appropriate means to reduce their use.  相似文献   
106.
107.
Purpose: To determine if adequate anaesthesia and akinesia could be obtained using an inferonasal quadrant sub-Tenons anaesthesia for cataract surgery.
Methods: The sub-Tenons method of local anaesthesia was used in 50 patients undergoing extracapsular cataract extraction and lens implantation. The technique followed was that described by JD Stevens in his study of 50 patients. Posterior sub-Tenons space was approached through a conjunctival incision in the inferonasal quadrant and the anaesthetic solution delivered by an irrigating cannula. The patients were assessed for residual ocular movements just before surgery. Effectiveness of anaesthesia was assessed during surgery using a verbal pain rating score. Scoring was based on the concept of a visual analogue pain score chart.
Results: Total akinesia was obtained in 20% patients and total anaesthesia in 24% patients. The remainder of the patients had adequate akinesia and anaesthesia to proceed with and complete the surgery.
Conclusion: This method provides satisfactory anaesthesia for cataract surgery.  相似文献   
108.
This review describes the usefulness of colour Doppler energy (CDE) (or power Doppler) imaging to measure vascularization in the female reproductive tract. CDE imaging is characterized by an increased sensitivity to flow, and thus may be useful in low-flow states and when optimal Doppler angles cannot be obtained. In addition, longer segments of vessels and more individual vessels can be visualized with CDE imaging. The role of CDE imaging in the evaluation of stromal vasculature in normal and in polycystic ovaries is described, and the relationship between follicular vascularity and outcome following in-vitro fertilization are discussed, together with the findings obtained from the evaluation of thecal arteriole of corpus luteum in early pregnancy. The fundamental role of CDE imaging in differentiation among ovarian masses is also reviewed. We summarize the role of CDE imaging in pregnancy, and describe two new applications of three-dimensional power Doppler sonography and the use of ultrasound contrast media. In conclusion, CDE imaging can replace conventional colour Doppler when the information on the direction of flow is not useful. Moreover, the technique appears superior to others for describing microvascular architecture and determining the presence or absence of flow.  相似文献   
109.
Quantitation of low hepatitis B virus (HBV) DNA levels in patients with chronic hepatitis B is important for monitoring natural history of disease and treatment efficacy. This study aimed to compare the quantitation range and analytical sensitivity of the newly developed COBAS TaqMan HBV test (TaqMan test) with the COBAS Amplicor HBV Monitor Test (Amplicor test), using the Eurohep HBV reference plasma and serum samples from patients. Serial dilutions (2.7x10(1)-2.7x10(8) copies/ml) of the Eurohep HBV reference plasma and 50 serum samples from chronic hepatitis B patients were tested by both assays. The TaqMan test could detect seven (2.7x10(2)-2.7x10(8) copies/ml) of eight dilutions of the reference plasma, while the Amplicor test could only detect three of them (2.7x10(3)-2.7x10(5) copies/ml). The HBV DNA values measured by the TaqMan test correlated very well with the theoretical Eurohep standard values (r=0.998, P<0.001). There were good correlations between the HBV DNA levels measured by the two assays on both the Eurohep reference plasma (r=0.993, P<0.001) and serum samples from patients (r=0.904, P<0.001). Compared to the Amplicor test, the TaqMan test had a higher sensitivity (50 vs. 300 copies/ml), shorter assay time (6 vs. 10 hr), and wider dynamic range (8 vs. 3 logs), and was more cost-effective in a clinical setting. These data indicate that the TaqMan test is an excellent tool for HBV DNA quantitation.  相似文献   
110.
The pleural space is modeled in two dimensions as a thin layer of fluid separating a deformable membrane and a rigid surface containing a bump. We computed the steady-state membrane configuration and fluid pressure distribution during relative sliding of the two surfaces. For physiologically relevant values of membrane tension, shear flow-induced pressures near the bump and far-field pressure gradients are similar to those measured in vivo within the pleural space (e.g. Lai-Fook et al.) [J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 56 (1984) 1633-1639]. Deformation of the membrane over the bump suggests that the pressure field generated by the sliding motion promotes an even layer of fluid in the pleural space, preventing asperities from touching. Results also suggest a possible mechanism for pleural fluid redistribution during breathing, whereby irreversible fluid motion is associated with the deformability of the membrane.  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