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   34548篇
  免费   3373篇
  国内免费   2429篇
耳鼻咽喉   280篇
儿科学   540篇
妇产科学   388篇
基础医学   3719篇
口腔科学   743篇
临床医学   4548篇
内科学   5173篇
皮肤病学   325篇
神经病学   1356篇
特种医学   1244篇
外国民族医学   15篇
外科学   3625篇
综合类   6077篇
现状与发展   7篇
一般理论   2篇
预防医学   2394篇
眼科学   1007篇
药学   3956篇
  22篇
中国医学   2104篇
肿瘤学   2825篇
  2024年   134篇
  2023年   552篇
  2022年   1322篇
  2021年   1896篇
  2020年   1469篇
  2019年   1187篇
  2018年   1249篇
  2017年   1215篇
  2016年   1102篇
  2015年   1684篇
  2014年   2102篇
  2013年   1962篇
  2012年   2750篇
  2011年   2886篇
  2010年   1994篇
  2009年   1616篇
  2008年   1956篇
  2007年   1866篇
  2006年   1766篇
  2005年   1416篇
  2004年   1110篇
  2003年   949篇
  2002年   831篇
  2001年   685篇
  2000年   659篇
  1999年   646篇
  1998年   446篇
  1997年   428篇
  1996年   377篇
  1995年   352篇
  1994年   319篇
  1993年   183篇
  1992年   211篇
  1991年   163篇
  1990年   134篇
  1989年   123篇
  1988年   131篇
  1987年   124篇
  1986年   104篇
  1985年   86篇
  1984年   32篇
  1983年   32篇
  1982年   20篇
  1981年   24篇
  1980年   12篇
  1979年   11篇
  1978年   9篇
  1977年   4篇
  1976年   6篇
  1975年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
后腹腔镜手术在泌尿外科的应用   总被引:5,自引:2,他引:3  
目的 探讨后腹腔镜手术治疗泌尿系疾病的方法及疗效。方法 采用后腹腔镜手术治疗泌尿系疾病3 5例 ,其中肾上腺肿瘤及肾上腺囊肿切除 13例 ,肾囊肿去顶术 15例 ,精索静脉曲张高位结扎术 4例 ,UPJ成形术 1例 ,乳糜尿行肾蒂淋巴管结扎术 1例 ,肾切除 1例。结果  3 5例手术全部成功。手术时间 3 0~ 13 0分钟 ,术中平均出血 2 0ml。术后住院时间 1.5~ 14天 ,平均 4.5天。结论 腹腔镜手术治疗泌尿系疾病 ,具有损伤小 ,住院时间短 ,恢复快 ,并发症少等优点 ,值得临床推广应用  相似文献   
102.
BACKGROUND: At present, researches on differentiating from human adipose-derived adult stromal cells (hADASC) to neuron-like cells are focus on inducing by artificial-synthetic compound solution; however, hippocampal astrocyte conditioned medium (HCAM) can induce in vitro differentiation from hADASC to neuron-like cells is still unclear. OBJECTIVE: To observe whether HCAM can induce in vitro differentiation from hADASC to neuron-like cells. DESIGN: Randomized control study. SETTING: Department of Neurology, Taixing People's Hospital; Central Laboratory, North China Coal Medical College. MATERIALS: Donor of adipose tissue was donated by female volunteers suffering from caesarean section in the department of obstetrics & gynecology in our hospital and aged 20-35 years. Adipose tissue was collected from subcutaneous tissue of abdomen during the operation. In addition, 8 male newborn Wistar rats within 24 hours with average body mass of 20 g were provided by Animal Institute of Chinese Academy of Medical Sciences. Rabbit-anti-human Nestin polyclonal antibody, rabbit-anti-human glial fibriliary acidic protein (GFAP) polyclonal antibody, rabbit-anti-human neuro-specific enolase polyclonal antibody and mouse-anti-human microtubal associated protein 2 (MAP-2) polyclonal antibody were provided by Wuhan Boster Company. METHODS: The experiment was carried out in the Central Laboratory of North China Coal Medical College from October 2004 to June 2005. hADASC was cultured with HCAM and its growth and morphological changes were observed under inverted phase contrast microscope. Immunocytochemistry, immunofluorescence and Western blotting were used to evaluate the expressions of Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. MAIN OUTCOME MEASURES: Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. RESULTS: On the 3rd day of culture, partial hADASC started deformation from slender shuttle-shape cells to neuron-like cells. It suggested that cells stretched out apophysis, which were mainly double-pole or multiple-pole cells. Five days later, immunohistochemical detection suggested that expression of Nestin (10.5±0.037) was found out in cells; meanwhile, expressions of GFAP (38.4±0.052) and neuro-specific enolase (NSE) (15.7±0.023) were also found out in cells; however, expression of MAP-2 was not observed. Western blot indicated that, 5 days after effect of HCAM, Nestin was found out in hADASC; meanwhile, expressions of GFAP and neuro-specific enolase were also found out; however, expression of MAP-2 was not observed. CONCLUSION: HCAM can induce the differentiation from hADASC to neuron-like cells in vitro.  相似文献   
103.
A variety of continuous and pulsed arterial spin labeling (ASL) perfusion MRI techniques have been demonstrated in recent years. One of the reasons these methods are still not routinely used is the limited extent of the imaging region. Of the ASL methods proposed to date, continuous ASL (CASL) with a separate labeling coil is particularly attractive for whole-brain studies at high fields. This approach can provide an increased signal-to-noise ratio (SNR) in perfusion images because there are no magnetization transfer (MT) effects, and lessen concerns regarding RF power deposition at high field because it uses a local labeling coil. In this work, we demonstrate CASL whole-brain quantitative perfusion imaging at 3.0 T using a combination of strategies: 3D volume acquisition, background tissue signal suppression, and a separate labeling coil. The results show that this approach can be used to acquire perfusion images in all brain regions with good sensitivity. Further, it is shown that the method can be performed safely on humans without exceeding the current RF power deposition limits. The current method can be extended to higher fields, and further improved by the use of multiple receiver coils and parallel imaging techniques to reduce scan time or provide increased resolution.  相似文献   
104.
After the chondrogenic potential of free grafts of perichondrium was shown in several experimental studies, perichondrium has been used to reconstruct cartilage tissue in various clinical situations. This study investigates the effects of human amniotic fluid on neochondrogenesis from free perichondrial grafts in a rabbit model. Since this fluid contains high concentrations of hyaluronic acid, hyaluronic acid-stimulating activator, growth factors, and extracellular matrix precursors during the second trimester, it may have a stimulating effect on neochondrogenesis. Perichondrial grafts, measuring 20 x 20 mm2 were obtained from the ears of 144 New Zealand young rabbits and were sutured over the paravertebral muscles. The rabbits were randomly divided into three groups with 48 rabbits per group. In group 1, 0.3 ml human amniotic fluid, and in group 2, 0.3 ml saline were injected underneath the perichondrial grafts. Group 3 formed the control group in which no treatment was given. Histologically, neochondrogenesis was evaluated in terms of cellular form and graft thickness at 2, 4, 6, and 8 weeks after surgery. In group 1, the mature cartilage was generated quickly and the cartilage plate in this group was significantly thick and extensive when compared with groups 2 and 3 at 8 weeks ( p<0.05 ANOVA). In conclusion, our study shows that human amniotic fluid enhances neochondrogenesis from free perichondrial grafts. The rich content of hyaluronic acid and growth factors possibly participate in this result.  相似文献   
105.
目的对不同体重老年腰椎管狭窄患者行单纯腰椎后路开窗减压手术,并评价其治疗效果。方法回顾性分析1996年12月~2002年12月间145例因老年腰椎管狭窄而采用单纯腰椎后路开窗减压手术治疗患者的病例资料,结合问卷调查患者对手术的满意程度,比较不同体重患者住院期间及术后症状改善情况,评估手术疗效。结果不同体重患者术后腰腿疼痛明显缓解、日常生活质量改善,患者对手术的满意率达67.59%。而且患者的各种统计数据表明,不同体重组之间差异无显著性意义(P>0.05)。结论体重在一定程度上影响老年腰椎管狭窄患者的手术治疗结果。单纯腰椎后路开窗减压手术,可以达到较为理想的治疗效果。  相似文献   
106.
女性压力性尿失禁的微创治疗   总被引:1,自引:0,他引:1  
目的探讨女性压力性尿失禁的发病机制和微创治疗方法。方法女性压力性尿失禁患者25例,经临床、尿动力学检查或膀胱尿道造影确诊,均为稳定性膀胱,无膀胱出口梗阻。采用无张力阴道吊带术(TVT),将吊带无张力置于尿道中段。结果手术时间平均(40±5)min;术中出血量平均(43±10)mL;术后平均留置导尿1.5 d;术后平均住院3 d。23例患者术后尿失禁症状均消失,其中2例患者术后出现尿潴留,留置导尿1周后好转,尿潴留症状消失,尿失禁未复发;2例尿失禁症状显著改善。结论TVT等微创术式因简单、微创、疗效好、并发症少等,目前是女性压力性尿失禁外科手术治疗的发展方向。  相似文献   
107.
目的探讨多巴酚丁胺负荷超声心动图(DSE)和组织多普勒成像技术(TDI)在冠心病(CHD)诊断中的应用价值,以寻求一种敏感的、无创的CHD诊断方法。方法选择胸闷或胸痛怀疑CHD患者40例,应用TDI测量静息状态(Rest)下前壁中段收缩峰值速度(Vs),以及多巴酚丁胺峰值负荷状态(Peak)下前壁中段Vs,同时测量静息心率和负荷心率;所有入选对象均进行冠脉造影,并根据左前降支狭窄程度是否大于等于50%分为左前降支狭窄组(LST组)与左前降支非狭窄组(non-LST组)。分别比较Rest和Peak前壁中段LST组与non-LST组平均Vs差别等。结果Rest前壁中段LST组与non-LST组Vs差别无显著性意义;但Peak前壁中段LST组与non-LST组差别有显著性意义。结论DSE结合TDI是诊断冠心病有价值的定量分析方法。DSE在诊断CHD时的敏感性、准确性明显优于静息状态超声心动图。  相似文献   
108.
目的①观察安博维(厄贝沙坦)干预治疗后环孢素A(CsA)所致慢性肾毒性大鼠肾脏病理变化。②观察安博维对CsA慢性肾毒性大鼠模型肾骨桥蛋白(OPN)表达及间质ED1阳性巨噬细胞浸润的影响,以探讨安博维防护CsA慢性肾毒性的可能机制。方法给进低盐饮食SD大鼠灌胃20mg·(kg·d)-1剂量的CsA制作大鼠CsA肾毒模型,同时以10mg·(kg·d)-1剂量的安博维胃饲以预防肾毒性。于用药后第1、2、4周末时分别处死各组大鼠,免疫组织化学法测定OPN、ED1的表达,用HE染色观察肾脏病理变化。结果安博维能明显改善CsA肾中毒大鼠的一般情况,减少肾小管上皮细胞空泡变性和萎缩,减少间质炎细胞浸润及间质纤维化。免疫组化结果显示模型组肾小管-间质OPN与ED1表达较对照组增加(p<0.05);在试验各时间点,安博维组大鼠肾小管-间质ED-1阳性巨噬细胞数量及OPN表达较模型组显著减少(p<0.05);OPN仍高于对照组((p<0.05),ED-1阳性巨噬细胞数量在第1、2周末与对照组无差异(p>0.05),但在第4周末高于对照组(p<0.05)。结论安博维能减轻CsA慢性肾毒性的肾脏病理损伤,这一防治作用可能与其减少ED-1阳性巨噬细胞浸润及下调OPN表达有关。  相似文献   
109.
1. Single applications of solutions of capsaicin were made to the intact skin of anaesthetized rats and the effects on cutaneous blood flow and the firing of C-nociceptor afferents determined. Blood flow was measured by laser-Doppler flowmetry. C-fibre activity was recorded from filaments dissected from the saphenous nerve. 2. Following the application of a capsaicin solution (concentration > or = 1 mM) to rat saphenous skin, low frequency firing occurred in C-polymodal nociceptors that sometimes continued for > 10 min. At the some time, large increases in skin blood flow occurred exceeding 300% in some instances. 3. After the initial excitation, some C-polymodal nociceptors lost their sensitivity to pressure whilst their sensitivity to heat was lost or enhanced depending on the vehicle used. 4. Sensitivity of C-polymodal nociceptors to heat recovered in < 1 day following a single application of 33 mM capsaicin. Thresholds to mechanical pressure, however, were still significantly elevated by 123% on day 1, but had recovered on day 2. 5. Vasodilatation in response to saphenous nerve stimulation ('antidromic vasodilatation') was significantly reduced by 35%, 2 days after a single application of 33 mM capsaicin, but was normal at 4 days. 6. Following a single application of 33 mM capsaicin, skin substance P levels fell to only half the normal value at day 1 and remained at this level throughout the 4 day period examined. 7. It is suggested that the ability of relatively low concentrations of capsaicin to desensitize C-fibre nociceptors may underlie the analgesic action of topical capsaicin in man.  相似文献   
110.
The articular cartilages from the left knee of 30 rabbits immobilized in casts in functional position were studied under transmission electron microscope. The pathological changes which begin at early stage of immobilization included both degeneration and repair of cartilage. The striking morphological features observed were: (1) most chondrocytes in various layers of cartilage underwent progresive degeneration; (2) the concomitant abnormal proliferation of some chondrocytes happened in a brief period. The changes in mechanical stress caused by immobilization affected the nutrition of cartilage and finally led to its reactive structural reformation.  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