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   90084篇
  免费   9550篇
  国内免费   6040篇
耳鼻咽喉   710篇
儿科学   1587篇
妇产科学   884篇
基础医学   8252篇
口腔科学   1725篇
临床医学   11206篇
内科学   11544篇
皮肤病学   964篇
神经病学   4136篇
特种医学   3590篇
外国民族医学   30篇
外科学   8916篇
综合类   18847篇
现状与发展   19篇
一般理论   4篇
预防医学   7721篇
眼科学   2308篇
药学   9988篇
  79篇
中国医学   6929篇
肿瘤学   6235篇
  2024年   381篇
  2023年   1400篇
  2022年   3516篇
  2021年   4541篇
  2020年   3670篇
  2019年   2938篇
  2018年   2965篇
  2017年   3105篇
  2016年   2832篇
  2015年   4091篇
  2014年   5170篇
  2013年   5512篇
  2012年   7696篇
  2011年   8026篇
  2010年   6058篇
  2009年   5174篇
  2008年   5715篇
  2007年   5455篇
  2006年   5148篇
  2005年   4294篇
  2004年   3469篇
  2003年   3248篇
  2002年   2556篇
  2001年   2045篇
  2000年   1538篇
  1999年   1185篇
  1998年   637篇
  1997年   697篇
  1996年   492篇
  1995年   409篇
  1994年   393篇
  1993年   241篇
  1992年   199篇
  1991年   178篇
  1990年   157篇
  1989年   127篇
  1988年   114篇
  1987年   86篇
  1986年   74篇
  1985年   42篇
  1984年   25篇
  1983年   25篇
  1982年   9篇
  1981年   7篇
  1980年   6篇
  1979年   5篇
  1978年   3篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Objective Pretargeting with radioactivity has significantly improved tumor to normal tissue radioactivity ratios over conventional antibody imaging in both animal studies and clinical trials. This laboratory is investigating DNA analogues such as phosphorodiamidate morpholinos (MORFs) for pretargeting using technetium-99m (99mTc) for detection. However, the unique properties of fluorescence activation and quenching combined with oligomers with their unique properties of hybridization may be particularly useful when used together for pretargeting with optical detection. The use of linear fluorophore-conjugated oligomer duplexes have been little used in animals, and to our knowledge, have not previously been considered for pretargeting applications. Methods A MORF/cDNA pair was selected such that when hybridized, the fluorescence of the Cy5.5-conjugated 25 mer MORF (Cy5.5–MORF25) is inhibited with a BHQ3-conjugated 18 mer complementary DNA (BHQ3–cDNA18). The short BHQ3–cDNA18 was selected to dissociate in the presence of a long cMORF25 in the pretargeted tumor, thus releasing the inhibitor from the Cy5.5 emitter. In this manner, the Cy5.5 fluorescence will be inhibited everywhere but in the target. The dissociation was first examined in vitro by adding the duplex to the cMORF25 both in solution and immobilized on polystyrene microspheres and by surface plasmon resonance (SPR). Thereafter, biotinylated cMORF25 immobilized on streptavidin polystyrene microspheres were administered intramuscularly in one thigh of hairless SKH-1 mice as target while an identical weight of the identical microspheres but without the cMORF25 was administered in the contralateral thigh as control. The animals then received IV the Cy5.5–MORF25/BHQ3–cDNA18 duplex or equal molar dosage of single-chain Cy5.5–MORF25 and were imaged. Results The SPR studies showed that the immobilized cDNA18 rapidly captured the flowing MORF25 to provide a duplex with a slow dissociation rate constant. Furthermore, when cMORF25 was next allowed to flow over the now immobilized duplex, the cDNA18 was unable to prevent dissociation of the heteroduplex and the formation and release of the cMORF25-MORF25 homoduplex. Images of animals obtained soon after receiving the Cy5.5–MORF25 singlet showed intense whole body fluorescence obscuring the target thigh. However, only 5 minutes after receiving the Cy5.5–MORF25/BHQ3–cDNA18 duplex, the target thigh was clearly visible along with only the kidneys. Conclusions This first study of optical pretargeting provides a proof of concept that oligomer pretargeting found to be useful with radioactivity detection is applicable with fluorescent detection as well. In addition, our results demonstrate that by using linear oligomers for optical pretargeting, chain lengths (and base sequences) may be manipulated to provide duplexes with stabilities and fluorescence inhibition optimized for pretargeting and other in vivo applications of optical imaging.  相似文献   
42.
43.
脾动脉栓塞治疗外伤性脾破裂28例临床疗效观察   总被引:3,自引:0,他引:3  
王佾 《中国综合临床》2002,18(8):729-730
目的:探讨脾动脉栓塞术对外伤性脾破裂的疗效及并发症的处理。方法:采用Seldinger法行脾动脉栓塞术治疗外伤性脾破裂28例。结果:所有患者出血立即停止,其中4例行2次栓塞。28例均有脾区疼痛,22例发热。脾动脉栓塞5天后血小板、白细胞上升近1倍,7天后恢复至正常范围。28例随访6-36月,查免疫球蛋白、CT等结果满意,未有再出血及发生暴发性感染。结论:脾动脉栓塞不但有良好的止血作用,而且能保留脾脏的免疫功能,可在非手术治疗失败时选用,是外伤性脾破裂的一种有效治疗方法。  相似文献   
44.
OBJECTIVE: To measure and compare Chinese mandibular genial tubercles measured anatomically and with computed tomography (CT). STUDY DESIGN AND SETTING: Spiral CT scans were taken of 40 adult human skulls; the superior genial spines were measured using anatomic and CT methods. RESULTS: The height and width of the superior genial spines, mandible thickness, and distance from the menton to the inferior and superior margins of the superior genial spines were 5.82 +/- 0.71, 6.98 +/- 1.35, 11.95 +/- 1.59, 11.08 +/- 2.05, and 16.91 +/- 2.30 mm from anatomic measurements and 6.17 +/- 0.71, 7.01 +/- 1.13, 12.19 +/- 1.64, 10.41 +/- 1.55, and 15.73 +/- 2.12 mm using spiral CT, respectively. The anatomic and CT measurements were correlated. CONCLUSION: Spiral CT of the genial tubercles can help locate the osteotomy in genioglossus advancement. SIGNIFICANCE: This study acquired reference data on Chinese genial tubercles demonstrating that CT measurements of the genial tubercles reflect their anatomy, which should allow accurately locate the osteotomy.  相似文献   
45.
FOREWORDPeritonealdialysisrepresentssoluteandfluidexchangemainlybetweenperitonealcapillarybloodanddialysissolutionintheperitonealcavity'CombinedwithhemodialySisandrenaltransplantation,peritonealdialysisisusedmainlyforthetreatmentofrenalfailure,particularlyforchronicfailure'In1976,Prof'Popovichdevelopedcontinuousambulatoryperitonealdialysis(CAPD)basingontheconceptofcontinuousequilibrationdialysis('1'Fromthenon,peritonealdialysisfounditsclinicaluse'Continuouscyclicperitonealdialysis(CCPD…  相似文献   
46.
MRI studies of first-pass contrast enhancement with polylysine-Gd-DTPA and myocardial tagging using spatial modulation of magnetization (SPAMM) were performed to assess the feasibility of a combined regional myocardial blood flow and 2D deformation exam. Instrumented closed-chest dogs were imaged at a baseline control state (Cntl) followed by two interventions: moderate coronary stenosis (St) achieved by partial occlusion of the left anterior descending (LAD) and moderate coronary stenosis with dobutamine loading (StD). Hypoperfusion of the anterior region (ANT) of the myocardium (LAD distribution) relative to the posterior wall (POS) based on the upslope of the signal intensity time curve from the contrast-enhanced MR images was demonstrated only with dobutamine loading (ANT:POS Cntl=1.077 ± 0.15 versus ANT:POS StD=0.477 ± 0.11, P<0.03) and was confirmed with radio-labeled microspheres measurements (ANT:POS Cntl=1.18 ± 0.2 ml/min/g versus ANT:POS StD=0.44 ± 0.1 ml/min/g; P<0.002). Significant changes in regional myocardial shortening were only seen in the StD state (P<0.02); the anterior region showed impaired myocardial shortening with dobutamine loading (P=NS), whereas the nonaffected POS region showed a marked increase in shortening when compared with Cntl (Cntl=0.964 ± 0.02 versus StD=0.884 ± 0.03; P<0.001). These results demonstrate that an integrated quantitative assessment of regional myocardial function and semiquantitative assessment of myocardial blood flow can be performed noninvasively with ultrafast MRI.  相似文献   
47.
Intravaginal misoprostol has been shown to be effective forcervical priming before a surgically induced abortion. The objectivewas to investigate the effectiveness of oral misoprostol incervical dilatation prior to vacuum aspiration between the 6thand 12th weeks of pregnancy. The results showed that in nulliparouspatients, the median cervical dilatation in the treatment group(7.8 mm) was significantly greater than that in the placebogroup (3.7 mm). In multiparous patients, the difference wasalso statistically significant (9.8 versus 6.0 mm). The easeof dilatation, assessed subjectively by the operating surgeons,was significantly improved in the treatment group. There wasalso a significant reduction in the duration of the operationand in the mean blood loss in the treatment group. The side-effectsencountered in the treatment group were mild and well acceptedby the women. Oral misoprostol is an effective and safe methodfor cervical dilatation prior to vacuum aspiration in firsttrimester pregnancy.  相似文献   
48.
我院多年来应用千捶膏和生肌玉红膏治疗感染性伤面。千捶膏用于去腐,生肌玉红膏用于生新。据我们观察二药有较强的抗感染作用,尤其有抗绿脓感染作用。应用千捶膏可以较快地达到脱腐作用,应用生肌玉红膏可以促进肉芽增生,达到伤面早期愈合,值得推广。  相似文献   
49.
磁刺激用平面线圈结构的优化研究   总被引:2,自引:0,他引:2  
文中建立了采用任意形状平面线圈磁刺激仪的RLC模型,给出了模型参数的计算方法。为了优化线圈,将磁刺激仪线圈的性能指标分为反映线圈输出性能的峰值磁能和反映线圈结构的几何变量。在磁刺激激活函数达到阈值条件下,调整平面螺旋线圈的结构并计算出依赖于线圈结构参数的输出性能值,从而,寻找最优的线圈几何参数。优化结果表明:线圈外半径是关键因素,给定阈值条件,选择合适的线圈外半径,可以大大降低线圈峰值磁能;另外,现在使用的圆环线圈并非最优,D形线圈优于圆环线圈。  相似文献   
50.
乙醇对人绒毛孕酮分泌的影响   总被引:1,自引:0,他引:1  
本工作利用灌流技术观察了四种不同浓度的乙醇(0.5%、1%、2.5%、5%)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。  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