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   20994篇
  免费   1150篇
  国内免费   95篇
耳鼻咽喉   270篇
儿科学   476篇
妇产科学   373篇
基础医学   2782篇
口腔科学   2063篇
临床医学   1574篇
内科学   4380篇
皮肤病学   463篇
神经病学   1517篇
特种医学   429篇
外国民族医学   2篇
外科学   2215篇
综合类   143篇
一般理论   2篇
预防医学   2976篇
眼科学   255篇
药学   1471篇
中国医学   225篇
肿瘤学   623篇
  2023年   187篇
  2022年   384篇
  2021年   806篇
  2020年   559篇
  2019年   667篇
  2018年   779篇
  2017年   576篇
  2016年   614篇
  2015年   699篇
  2014年   933篇
  2013年   1106篇
  2012年   1652篇
  2011年   1827篇
  2010年   892篇
  2009年   649篇
  2008年   1230篇
  2007年   1279篇
  2006年   985篇
  2005年   890篇
  2004年   804篇
  2003年   712篇
  2002年   605篇
  2001年   399篇
  2000年   403篇
  1999年   313篇
  1998年   110篇
  1997年   80篇
  1996年   57篇
  1995年   73篇
  1994年   69篇
  1993年   55篇
  1992年   161篇
  1991年   134篇
  1990年   155篇
  1989年   130篇
  1988年   123篇
  1987年   78篇
  1986年   89篇
  1985年   70篇
  1984年   47篇
  1983年   51篇
  1979年   61篇
  1974年   40篇
  1973年   43篇
  1970年   58篇
  1969年   73篇
  1968年   54篇
  1967年   56篇
  1966年   48篇
  1965年   36篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Taking a patient-oriented approach to developing lifestyle interventions includes incorporating the patient into the program’s design, delivery, and evaluation. This commentary assumes that a patient-oriented approach has not yet been implemented and tested in exercise-based interventions designed for pregnant women. We outline and define a patient-oriented approach to conduct exercise-based research and review previous physical activity interventions designed for pregnant women to determine whether a patient-oriented approach was applied. In addition, pregnant women living with obesity may have unique barriers to engaging in prenatal exercise interventions that have not been previously addressed, such as having experienced weight stigma before pregnancy in healthcare and fitness settings. We propose suggestions for future trials to effectively take a patient-oriented approach when designing and implementing prenatal exercise interventions to address patient-informed barriers and incorporate suggested facilitators for physical activity. Given that prenatal activity levels are low and pregnant women may have unique barriers to engaging in exercise interventions, a patient-oriented approach may be an effective strategy to improve inclusivity and equity and, as a result, increase uptake and adherence to the intervention.  相似文献   
172.
Vaccine adjuvants are compounds that enhance/prolong the immune response to a co-administered antigen. Saponins have been widely used as adjuvants for many years in several vaccines – especially for intracellular pathogens – including the recent and somewhat revolutionary malaria and shingles vaccines. In view of the immunoadjuvant potential of Q. brasiliensis saponins, the present study aimed to characterize the QB-80 saponin-rich fraction and a nanoadjuvant prepared with QB-80 and lipids (IMXQB-80). In addition, the performance of such adjuvants was examined in experimental inactivated vaccines against Zika virus (ZIKV). Analysis of QB-80 by DI-ESI-ToF by negative ion electrospray revealed over 29 saponins that could be assigned to known structures existing in their congener Q. saponaria, including the well-studied QS-21 and QS-7. The QB-80 saponins were a micrOTOF able to self-assembly with lipids in ISCOM-like nanoparticles with diameters of approximately 43 nm, here named IMXQB-80. Toxicity assays revealed that QB-80 saponins did present some haemolytical and cytotoxic potentials; however, these were abrogated in IMXQB-80 nanoparticles. Regarding the adjuvant activity, QB-80 and IMXQB-80 significantly enhanced serum levels of anti-Zika virus IgG and subtypes (IgG1, IgG2b, IgG2c) as well as neutralized antibodies when compared to an unadjuvanted vaccine. Furthermore, the nanoadjuvant IMXQB-80 was as effective as QB-80 in stimulating immune responses, yet requiring fourfold less saponins to induce the equivalent stimuli, and with less toxicity. These findings reveal that the saponin fraction QB-80, and particularly the IMXQB-80 nanoadjuvant, are safe and capable of potentializing immune responses when used as adjuvants in experimental ZIKV vaccines.  相似文献   
173.
Quality of Life Research - As people around the world are facing the Covid-19 outbreak, their perception of oral health problems could be changed. This study aimed to evaluate the immediate effects...  相似文献   
174.
A novel methodology for characterization of animal sperm shape involving the use of a spectral approach to multiscale curvature estimation is proposed. By using the derivative property of the Fourier transform, allied to Gaussian smoothing, accurate estimates of the curvature along the sperm contour can be obtained in such a way that the curvature peaks corresponding to the sperm head vertices can be effectively identified. The measurements derived from such a processing, namely the width of the basal region of the head, the centralization of tail implantation, and the multiscale bending energy, provide valuable resources for fertility and phylogenetic studies.  相似文献   
175.
A new technique to correct persistent left superior vena cava (LSVC) drainage into the left atrium is described in a 14-year-old patient with situs inversus, left atrial isomerism common atrium, and mitral valve regurgitation. During surgery, occlusion of the LSVC markedly increased the venous pressure, precluding its ligation. Because of the malposition of the heart and the unusual atrial anatomy, correction with an intra-atrial baffle was not attempted. After correcting the intra-cardiac anomaly, the LSVC was divided and anastomosed to the "right" atrial appendage using a segment of PTFE graft. The postoperative course was uneventful and an angiogram demonstrated excellent performance of the graft.  相似文献   
176.
Precordial exercise electrocardiographic mapping and exercise 201-thallium scintigraphy were simultaneously used on sixteen patients before, shortly after and three months after percutaneous transluminal coronary angioplasty (PTCA) to evaluate the immediate and late results of the intervention. In spite of the limited number of observations, positive exercise precordial mapping and or a reversible 201-thallium perfusion defect after PTCA seem to be indicative of failure of balloon dilatation or of development of restenosis in a given coronary artery. "Reverse minimum", that is the minimum in the resting precordial map which disappears on exercise, may be a sign of segmental coronary artery occlusion and well functioning collateral supply.  相似文献   
177.
The authors review the cases of traumatic rectal injuries admitted to the Emergency Service of the "Hospital das Clínicas", University of S?o Paulo Medical School, during the period of July 1981 to July 1988. Forty-five patients (62.5%) had their injuries due to gunshot, 14 (19.4%) due to foreign bodies on the rectum, 10 (13.8%) due to blunt trauma and 3 (4.1%) due to stab wounds. The intraperitoneal rectum was injured in 32 patients (44.4%) and extraperitoneal portion of the rectum in 40 patients (55.5%). On the intraperitoneal injuries the management adopted were simple suture (14 patients), associated with a colostomy (17 patients) and in one patient the Hartmann procedure was adopted. On the extraperitoneal wounds the management adopted were rectal repair (when feasible), colostomy, distal washout and drainage. The complications rate was 27.8%, and from them, the majority (70%) were related to infectious nature. Seven patients died (9.7%), four of them as a consequence of sepsis. The morbidity and mortality of the rectal injuries were closed related to infectious complications as a consequence of late diagnosis. For this reason, the authors consider that all efforts should be employed to establish the prompt diagnosis.  相似文献   
178.
目的:研究氢化可的松对豚鼠离体气管平滑肌收缩活动的影响。方法:用组胺和乙酰胆碱引起气管条明显收缩和张力增加。用氢化可的松20-30秒后,观察组胺和乙酰胆碱所引起的气管条收缩活动的改变。结果:用氢化可的松20~30s后,组胺和乙酰胆碱所引起的气管条收缩活动减弱、张力明显降低。结论:氢化可的松可以快速舒张豚鼠气管平滑肌。  相似文献   
179.
妊娠期雌二醇和催乳素与瘦素的关系   总被引:2,自引:0,他引:2  
目的 研究妊娠期间性激素与瘦素水平之间的关系。方法 在180例不同孕周的妇女中,按孕周分为<20周组,20-23周组,≥28周组,采用酶联免疫吸附法测定其外周血血清雌二醇(E2)和催乳素(PRL),放射免疫法测定血清瘦素水平,分析这些激素之间的相互关系。结果 E2和PRL均随妊娠进展而逐步升高(P<0.0001),组间均有显著差异(P<0.05)。各组瘦素水平均高于非妊娠组,但组间差异无显著性。瘦素水平与孕妇体重及体重指数显著相关(P0.01),与PRL也呈相关(P<0.05),而与E2无明显相关。结论 PRL水平与妊娠期瘦素水平升高有一定关系。  相似文献   
180.
目的:用定量超声方法对有骨折史的骨质疏松症患者进行骨量检查,方法用CUBA Clinical型定量骨密度超声仪对393例被疑为骨质疏松的患者进行检测,并根据病史按有无骨折中进行分组。分析二组患者宽频超声衰减(BUA)、超声速率(VOS)、强度指数(SI)与骨折次数的关系。结果:伴有骨折史的骨质疏松症虱的BUA、VOS、SI值都要比无骨折史的患者明显降低(P=0.000)。结论定量超声值与骨折的发生次数呈负相关,其测定值越低,骨折的发生次数越多;骨的质量下降是造成骨质疏松骨折的主要原因。  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