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   14658篇
  免费   1361篇
  国内免费   347篇
耳鼻咽喉   10篇
儿科学   304篇
妇产科学   181篇
基础医学   998篇
口腔科学   27篇
临床医学   1370篇
内科学   669篇
皮肤病学   37篇
神经病学   230篇
特种医学   200篇
外国民族医学   11篇
外科学   6695篇
综合类   2025篇
现状与发展   1篇
预防医学   356篇
眼科学   39篇
药学   885篇
  7篇
中国医学   249篇
肿瘤学   2072篇
  2024年   55篇
  2023年   205篇
  2022年   394篇
  2021年   556篇
  2020年   536篇
  2019年   519篇
  2018年   492篇
  2017年   549篇
  2016年   468篇
  2015年   593篇
  2014年   1013篇
  2013年   1023篇
  2012年   799篇
  2011年   1028篇
  2010年   852篇
  2009年   785篇
  2008年   707篇
  2007年   667篇
  2006年   738篇
  2005年   640篇
  2004年   557篇
  2003年   501篇
  2002年   430篇
  2001年   368篇
  2000年   254篇
  1999年   196篇
  1998年   177篇
  1997年   146篇
  1996年   117篇
  1995年   98篇
  1994年   123篇
  1993年   70篇
  1992年   72篇
  1991年   58篇
  1990年   74篇
  1989年   52篇
  1988年   56篇
  1987年   57篇
  1986年   38篇
  1985年   51篇
  1984年   45篇
  1983年   37篇
  1982年   34篇
  1981年   17篇
  1980年   25篇
  1979年   24篇
  1978年   27篇
  1977年   9篇
  1976年   10篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The regulatory effect of prostaglandin (PG) E2 and a cyclooxygenase (COX) inhibitor on Bacille Calmette-Guérin (BCG)-induced macrophage cytotoxicity in a bladder cancer cell, MBT-2, was studied in vitro. BCG stimulated thioglycollate-elicited murine peritoneal exudate cells (PEC) to induce cytotoxic activity and to produce cytokines such as interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and PGE2. NS398, a specific COX-2 inhibitor, and indomethacin (IM), a COX-1 and COX-2 inhibitor, enhanced viable BCG-induced cytotoxic activity and IFN-gamma and TNF-alpha production of PEC. However, NS398 and IM did not enhance these activities induced by killed BCG. Enhanced cytotoxicity was mediated by increased amounts of IFN-gamma and TNF-alpha. Exogenous PGE2 reduced cytotoxic activity and IFN-gamma and TNF-alpha production of PEC. These results suggest that PGE2 produced by BCG-activated macrophages has a negative regulatory effect on the cytotoxic activity of macrophages. Accordingly, a PG synthesis inhibitor may be a useful agent to enhance BCG-induced antitumour activity of macrophages.  相似文献   
102.
The discharge characteristics of sacral visceral afferents supplying the urinary bladder, urethra, colon and anus to mechanical stimuli were analyzed in the anaesthetized cat. The stimuli used were passive distension (urinary bladder, colon), isovolumetric contraction (urinary bladder), movements of the urethral catheter and mechanical shearing stimuli (mucosal skin of the anal canal). (1) In total 245 afferent units which projected in the pelvic nerve were isolated from the sacral dorsal roots. From one of the following organs, urinary bladder, colon, urethra and anus 117 afferent units were activated. By these stimuli from the bladder, urethra and anus 122 afferent units could not be activated, and as far as tested also not from the colon; in 6 afferent units the classification was unclear. (2) Afferent units from the urinary bladder and the colon responded consistently to passive distension of the respective organ. The units from the urinary bladder showed graded responses at intraluminal pressures of about 10–70 mm Hg and responded also to isovolumetric contractions of the organ. The thresholds of the units from the bladder to passive distension and contraction varied from about 5 to 20 mm Hg intravesical pressure. (3) The afferent units from the urethra and the anus did not react or showed some weak phasic and irregular responses to distension and contraction applied to the urinary bladder or to distension of the colon. They were consistently excited by low threshold mechanical stimulation of the urethra and anus, respectively. (4) The axons from the bladder, urethra and anus were presumably myelinated (conduction velocity above 2 m/s) and conducted at 10.3±6.1 m/s (n=34, mean±SD), 26.3±9.3 m/s (n=13) and 9.5±5.1 m/s (n=37), respectively. The axons from the colon conducted at about 0.5 to 16 m/s (n=20), 13 of them conducting at less than 2 m/s. About 75% of the axons which could not be activated by mechanical stimulation of the visceral organs were presumably unmyelinated (conduction velocity below 2 m/s). (5) Some ongoing activity was found in 9 out of 26 afferent units from the anus but, with one exception, the afferent units from the bladder, urethra and colon were silent. (6) It is concluded that the pelvic afferent units from the urinary bladder, urethra, colon and anus consist of distinct populations with characteristic response patterns. There is no indication from this investigation that the urinary bladder is supplied by sacral afferents which are only recruited at high intravesical pressures during passive distension and isovolumetric contractions and which are possibly associated with pain.Supported by the Deutsche Forschungsgemeinschaft  相似文献   
103.
妇产科手术泌尿系损伤防治方法的探讨   总被引:4,自引:2,他引:4  
目的 探讨妇产科手术泌尿系损伤的特点及防治方法,为临床妇产科手术中防止泌尿系损伤提供参考。方法 对我院妇产科手术中发生的泌尿系损伤的10例临床资料进行回顾性分析。结果 10例患者中输尿管损伤3例,均为术中发现,术中行输尿管端端吻合;膀胱损伤7例,其中5例于术中发现,2例术后形成膀胱阴道瘘,行膀胱修补术,所有病例均痊愈出院。妇产科损伤泌尿系的主要原因有输尿管解剖移位,盆腔粘连严重等。结论 绝大多数妇产科手术中的泌尿生殖系损伤是可以防范的,一旦发生,应及时发现,尽早修补预后良好。  相似文献   
104.
目的为明确Survivin作为膀胱肿瘤患者的肿瘤诊断和监测标志物的可能性,我们检测了Survivin在膀胱肿瘤和非肿瘤患者病变组织的Survivin蛋白及其mRNA表达情况。方法从我科住院病人和膀胱镜检患者中获取31例膀胱癌患者(实验组)和24例非肿瘤患者(对照组)的组织标本,用免疫组织化学法(IHC)和RT-PCR检测Survivin蛋白和基因在肿瘤组织和非肿瘤组织中的表达情况。并对结果行相应的统计学分析。结果IHC检测实验组和对照组Survivin蛋白的阳性率分别为74%(23/31)和4%(1/24),χ2检验P<0.001,IHC的阳性率与肿瘤的分级分期有一定的关系;实验组和对照组RT-PCR检测Survivin mRNA的表达阳性率分别为90%(30/31)和4%(1/24),χ2检验P<0.001。结论膀胱肿瘤组织Survivin蛋白和基因的表达量高于对照组,因此,Survivin有望成为膀胱瘤高危人群筛选,肿瘤诊断和监测的工具之一。  相似文献   
105.
European sea bass (Dicentrarchus labrax) are euryhaline fish that tolerate wide salinity fluctuations owing to several morphofunctional adaptations. Among the osmoregulatory sites (tegument, branchial chambers, digestive tract, urinary system), little is known about the kidney and the urinary bladder. The present study describes the ontogeny of the urinary system (kidney and urinary bladder) and focuses on the progressive expression of the Na+/K+-ATPase in the cells of these ion-transporting epithelia. A structural approach has shown that two pronephric urinary tubules are already present at hatching while the urinary bladder starts to differentiate. The glomus, an ultrafiltration site, occurs at day 5 (D5). The opisthonephros differentiates at D19/25 from the pronephric collecting tubules, then it rapidly grows longer and becomes folded. Na+/K+-ATPase immunolocalization and transmission electron microscopy show that ionocyte-like cells line the urinary tubules and the dorsal wall of the urinary bladder from D2/D5 on. Tubule ionocytes present a basolateral-localized fluorescence. Ionocytes of the collecting ducts and of the dorsal wall of the bladder present a fluorescence distributed in the whole cytoplasm. Fluorescence becomes stronger in later stages, suggesting a progressively increasing functionality of the urinary system in active ion transports. This observation is closely correlated with the ontogeny of osmoregulatory abilities. In juvenile and preadult fish kept in seawater, osmolality measurements demonstrate that urine is isotonic to blood. At low salinity, urine is hypotonic to blood in both stages. The capacity to produce hypotonic urine increases during ontogeny, a fact that suggests an increasing involvement of the urinary system in osmoregulation. The occurrence and the progressive functionality of the urinary system during the ontogeny, along with those of other osmoregulatory sites, are major adaptations allowing the sea bass to live in habitats of variable salinity such as lagoons and estuaries.  相似文献   
106.
本文报道以1%乙酸冲洗雌性Wistar大鼠膀胱和雌性新西兰白兔膀胱,分别获得其膀胱酸溶性提取物。AU-PAGE分析表明,两种膀胱粘膜酸溶性提取物都有十余条主蛋白带,而不含常见的杀菌物质溶菌酶和防御素样分子。琼脂糖弥散法杀菌试验显示,两种膀胱粘膜酸溶性提取物对致病性大肠杆菌ML-35p耐药株都有杀菌活性。进一步采用电泳凝胶琼脂糖弥散法杀菌试验分析,结果表明大鼠膀胱粘膜酸溶性提取物中有两条蛋白带具明显的杀菌活性,我们称这两条蛋白带为RatBP-1和RatBP-2。而兔膀胱粘膜酸溶性提取物的杀菌活性亦与两条被称为RabBP-1和RabBP-2的蛋白带相关。本文首次提示,在膀胱粘膜内存在抗菌蛋白,可能是膀胱粘膜杀菌作用的分子基础。  相似文献   
107.
Force generation and tissue glucose metabolism were measured in the urinary bladder smooth muscle from rats with streptozotocin-induced diabetes (7–8 wk duration). Bladder wet wt was almost 4–fold higher in the diabetic animals compared with the untreated controls. Morphological analysis showed that the growth was associated with hypertrophy of the smooth muscle component in the bladder wall. Force generation of isolated bladder strip preparations was measured in vitro at different ambient oxygen tensions. Activation of intramural nerves, with electrical field stimulation, induced contractions that were unaffected by reduction of oxygen tension down to Po2 100 mmHg for both control and diabetic muscle strips. At zero Po2 force was reduced by approximately 10–20% in both groups. High-K+ solution induced ‘tonic’ contractions that were slightly more inhibited by lowering Po2. At intermediate Po2 (between 100 and 20 mmHg) the diabetic muscle gave slightly higher force. At zero Po2 no significant difference could be detected between strips from control and diabetic animals. Oxygen consumption and lactate production in the preparations were determined at a Po2 of 290 mmHg and related to the volume of smooth muscle. At zero Po2 lactate formation increased 3- to 4-fold. The metabolic tension cost was lower at zero Po2 No differences in basal and contraction related metabolic rates could be detected between the two groups under normoxic and anoxic conditions. The maximal activity of lactate dehydrogenase (LDH) determined in tissue sampIes was about 2-fold higher in the diabetic bladder muscle. This increased enzymatic activity could thus not be correlated with any altered metabolic properties of the smooth muscle in the urinary bladder from diabetic rats.  相似文献   
108.
Expression of rat urinary bladder cathepsin E in benign papillomatosis induced by uracil and various stages of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced carcinogenesis was investigated immunohistochemically. Seven-week-old, male F344/DuCrj rats were used. In the normal urothelium of control rats, cathepsin E stained in all layers of cells, although in umbrella cells and some basal cells the reaction was relatively weak. In rats given a diet containing 3% uracil for 5 weeks immunoreactivity of cathepsin E in uracil-induced papillomatosis was consistently homogeneous in all layers, but weaker than in normal urothelium. In rats given 0.05% BBN in drinking water for 12 weeks and subsequently maintained without treatment for 48 weeks cells with little cathepsin E, never observed in normal urothelium, appeared at 5 weeks above the basement membrane in the earliest stage of BBN-induced urinary bladder cancer (simple hyperplasia). Throughout the neoplastic process, groups of cells with a little cathepsin E were randomly distributed, with expression in the urothelium being markedly unstable. Almost all areas of squamous cell proliferation in TCC were negative for cathepsin E. Instability of cathepsin E expression in rat urothelium therefore appears characteristic for carcinogenesis and offers the possibility of using this feature as an early biomarker for urinary bladder carcinogenesis.  相似文献   
109.
 This case report describes a chondroma of the bladder in a 63-year-old woman with clinical complaints of pain in the left fossa iliaca. The lesion was a tumour with a lobulated growth pattern composed of chondrocytes embedded in a chondroid matrix. Neither mitotic figures nor increased cellularity were present. Nuclei were inconspicuous. Immunohistochemical examination showed reactivity for S100 and vimentin. Received: 22 April 1997 / Accepted: 25 August 1997  相似文献   
110.
A new form of morphogenesis of pathological process, cystopathy, was distinguished on the basis endoscopy data and morphofunctional analysis of the urinary bladder in chronic cystitis. Cystopathy is characterized by predominance of diffuse degeneration and atrophy of the urothelium, stromal sclerosis, absence of inflammatory cell infiltration, and inhibition of biosynthetic reactions in urothelial cells (compared to chronic cystitis). Cystopathy results from regeneratory and plastic failure. Instability of the bladder epithelium can be a morphological marker of oncological risk.  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