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   116701篇
  免费   11767篇
  国内免费   8726篇
耳鼻咽喉   963篇
儿科学   1355篇
妇产科学   981篇
基础医学   11614篇
口腔科学   1856篇
临床医学   14695篇
内科学   15420篇
皮肤病学   922篇
神经病学   5450篇
特种医学   4423篇
外国民族医学   49篇
外科学   12121篇
综合类   24817篇
现状与发展   27篇
一般理论   20篇
预防医学   9429篇
眼科学   2612篇
药学   12975篇
  130篇
中国医学   8482篇
肿瘤学   8853篇
  2024年   491篇
  2023年   1824篇
  2022年   4688篇
  2021年   5821篇
  2020年   4754篇
  2019年   3664篇
  2018年   3807篇
  2017年   3705篇
  2016年   3329篇
  2015年   5405篇
  2014年   6818篇
  2013年   6724篇
  2012年   9560篇
  2011年   10712篇
  2010年   7693篇
  2009年   6469篇
  2008年   7225篇
  2007年   6999篇
  2006年   6499篇
  2005年   5837篇
  2004年   4232篇
  2003年   3855篇
  2002年   3308篇
  2001年   2595篇
  2000年   2219篇
  1999年   1801篇
  1998年   1142篇
  1997年   1180篇
  1996年   864篇
  1995年   792篇
  1994年   601篇
  1993年   436篇
  1992年   373篇
  1991年   309篇
  1990年   281篇
  1989年   273篇
  1988年   204篇
  1987年   190篇
  1986年   137篇
  1985年   129篇
  1984年   60篇
  1983年   41篇
  1982年   34篇
  1981年   29篇
  1980年   18篇
  1979年   19篇
  1978年   7篇
  1973年   5篇
  1972年   6篇
  1971年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
目的 探讨严重创伤后肝细胞凋亡及坏死在急性肝功能障碍发病机制中的作用。方法复制多发性骨折合并休克的大鼠创伤模型,采用 Annexin-V-Flous、碘化丙锭(propidium iodid,PI)双标法经流式细胞仪检测创伤后各时间点肝细胞凋亡与坏死的数量变化,结合光镜、电镜和电泳观察细胞凋亡与坏死,并与肝功能变化相比较。结果创伤后早期肝细胞即发生凋亡和坏死,坏死肝细胞的数量进行性升高,与肝功能变化显著呈正相关;凋亡肝细胞在创伤后3h达高峰,部分凋亡肝细胞发生继发性坏死,其数量与肝功能变化显著正相关。结论肝细胞坏死与凋亡是严重创伤后肝功能损害的重要原因,坏死肝细胞是肝功能损害的直接因素,凋亡肝细胞通过发生继发性坏死加重肝功能损害。  相似文献   
22.
保留肾单位手术治疗早期小肾癌21例临床分析   总被引:1,自引:0,他引:1  
OBJECTIVE: To evaluate the clinical effects of nephron-sparing surgery in patients with early-stage small renal cell carcinoma. METHODS: Nephron-sparing surgery was performed in 21 patients with renal cell carcinoma including 1 with solitary kidney, 3 with unilateral tumor and contralateral renal compromise, and 17 with unilateral tumor and normal contralateral kidney. The diameter of the tumors ranged from 1.5 to 6.0 cm, with a mean of 2.8 cm. The tumor diameter in 17 patients with normal contralateral kidney was less than 4 cm (mean 2.5 cm) and the average diameter in 4 patients with contralateral renal compromise was 4.2 cm. Sixteen cases were in stage T(1), 4 in stage T(2), and 1 in stage T(3). Of the 21 patients, 4 underwent tumor enucleation, 10 polar nephrectomy and 7 wedge resection. RESULTS: All patients were followed up for an average of 40.8 months (7 to 66 months). One patient suffered a right lung and mediastinum metastasis 3 years after the surgery later and 1 with chronic glomerulonephritis required dialysis 27 months after the operation. No surgical complication or local recurrence were found in other patients. CONCLUSION: As a safe and effective therapy for early-stage small renal cell carcinoma, nephron-sparing surgery can be considered as the gold-standard therapy for patients with lesions less than 4 cm in T(1) and T(2) stages of localized unilateral tumor with normal contralateral kidney.  相似文献   
23.
Lymphoid neogenesis is the process by which ectopic lymphoid accumulations that resemble lymph nodes arise in nonlymphoid tissues. Such lymphoid accumulations, known as tertiary lymphoid organs (TLO), are observed in chronic autoimmunity and they propagate immune pathology by setting up local antigen presenting sites. Whether lymphoid neogenesis occurs in transplanted organs and contributes to rejection is not well understood. To begin to address this question, we retrospectively analyzed 319 murine cardiac allografts for microscopic evidence of lymph-node-like structures. We found 78 allografts that had either classical TLO, characterized by discrete T- and B-cell zones and high endothelial venules (HEV) expressing peripheral node addressin (PNAd) (n = 34), or PNAd(+) HEV without organized lymphoid accumulations (n = 44). These changes were present in both short- and long-lived allografts and were invariably associated with rejection. Importantly, they occurred in 78% of allografts undergoing chronic rejection (n = 85) but in only 7% of allografts undergoing primarily acute rejection (n = 184). These findings indicate that, like autoimmunity, alloimmunity is associated with lymphoid neogenesis in the target organ and suggest a role for local T-cell activation in chronic allograft rejection.  相似文献   
24.
红细胞调控白细胞免疫功能新的自然实验研究体系   总被引:4,自引:0,他引:4  
目的用血液免疫反应路线图实验体系评估红细胞在白细胞免疫活性中的作用。方法将0·3ml血浆加入0·2ml全血细胞悬液(全血细胞组)或0·2ml白细胞悬液(白细胞组)中,37℃温育1h,用免疫酶联法测定IL-8和IL-12水平,流式细胞仪测定白细胞膜CD4、CD8、CD35和CXCR4表达量。结果全血细胞组IL-8和IL-12水平(分别为5·96±4·26、9·84±2·23ρB·pg-1·ml-1)明显低于白细胞组(分别为15·09±9·86、13·59±3·69ρB·pg-1·ml-1,P<0·05),淋巴细胞CD4、CD35、CXCR4表达量(分别为37·79±12·00、154·66±70·00、34·40±20·45)明显高于白细胞组(分别为18·54±11·32、83·26±35·99、16·69±11·09,P<0.01),粒细胞CD35表达量(603·63±257·64)明显高于白细胞组(384·86±174·16,P<0.01)。成人全血细胞组淋巴细胞和粒细胞CD35和CXCR4表达量明显高于脐血全血细胞组(P<0·05或P<0·01)。结论红细胞是白细胞(包括T淋巴细胞、B淋巴细胞、NK细胞、树突状细胞、粒细胞等)免疫功能的调控者和指导者,脐血红细胞免疫调节功能明显下降;本研究为红细胞免疫调控活性测定提供了新的近似自然的方法。  相似文献   
25.
We previously reported that lymphatic mapping using isosulfan blue can be used to identify sentinel nodes (SNs). This study was undertaken to evaluate the feasibility of using the SN technique in treating early gastric cancer and to explore its usefulness for minimal invasive surgery. Twenty-three patients with early gastric cancer who underwent SN biopsy were retrospectively evaluated. Based on SN evaluation, individualized surgery was performed in five patients with T1N0M0 gastric cancer. When pathological examination of frozen sections revealed metastasis in SNs, we performed a standard D2 gastrectomy. Laparoscopic local resection was applied when the SN biopsy was negative. Our results showed that the success rate with SN biopsy in early gastric cancer was 100%, as were the accuracy, sensitivity, and specificity. All five patients with early gastric cancer had SNs negative for metastases both by frozen section and by postoperative pathology. Thus, all these patients underwent laparoscopic local resection without extended lymphadenectomy. We conclude that SN biopsy is a useful tool to individualize the operative procedure, and laparoscopic local resection can be safely performed using SN guidance in selected patients with early gastric cancer.  相似文献   
26.
本文应用核磁共振法(NMR)测定了几种混合体系的 HLB 值与混合体系中各组分的 HLB 值。实验结果表明,混合体系中各组分在核磁共振图谱中的积分曲线高度也具有加和性。混合体系的 HLB 值是体系中各组分 HLB 值的加权平均值。因此,对混合体系的 HLB 值可以应用 NMR 法直接测定,也可应用 NMR 法测定各组分的 HLB值,通过计算求得,计算值与实测值完全一致。  相似文献   
27.
淋巴瘤样肉芽肿与韦格内肉芽肿临床特点的比较   总被引:2,自引:0,他引:2  
戚务芳  蒋明  赵岩 《北京医学》2005,27(1):15-17
目的 总结淋巴瘤样肉芽肿病(lym phom atoid granulom atosis,LG)与韦格内肉芽肿( egener granulo Wm atosis,W G)的临床特点,从临床上加以鉴别。 方法 回顾性总结我院与北京协和医院 1989 年以来收治的 6 例 LG和20 例 W G 患者的临床资料,并进行比较。 结果 发热、咳嗽及呼吸困难在 LG 中较常见,流涕、鼻衄及关节痛以W G 为多,肺受累以 LG 为多,耳鼻喉、眼及肾病变在 W G 中明显增多,皮肤受损两者相似。W G 患者常有 c-ANCA 阳性及尿沉渣异常。 LG X 线胸片为双侧多发结节,边界不清,多无肺门、纵隔淋巴结肿大; G 则为双侧多发边界清晰W的结节, 易形成空洞, 肺门和纵隔淋巴结可肿大。LG 病理改变为血管中心性淋巴增生性病变, 浸润的细胞主要是小淋巴细胞和不同数量大的不典型淋巴细胞; 而在 W G 中可见坏死性血管炎及大量中性白细胞、浆细胞及少量嗜酸细胞浸润形成的肉芽肿, 部分有多核巨细胞。W G 经治疗后, 多数患者病情缓解; 则疗效不佳。 结论 LG 和 W G 在临 LG床表现、实验室检查、 影像及病理诸方面的差异有利于两者的鉴别诊断。  相似文献   
28.
While extensive evidence suggests that adrenoceptors play an important role in the control of growth hormone in the rat, there are few studies involving the direct measurement of growth hormone-releasing hormone (GHRH). We have therefore developed a radioimmunoassay for rat GHRH, and used it to investigate the modulation of GHRH release by noradrenaline from incubated rat hypothalamus in vitro. The GHRH radioimmunoassay had no significant cross-reactivity with other hypothalamic or GHRH-related peptides, and was sensitive to 4 pg/tube; intra- and interassay coefficients of variation were 6% and 12% respectively. Single incubated rat hypothalami produced a stable and readily measurable output of GHRH in successive 20 min incubations after an initial 60 min preincubation; the release of GHRH was increased in the presence of 56 mM KCI, but did not respond to KCI-depolarization when calcium was excluded from the medium. Stimulated GHRH release was identical to synthetic rat GHRH(1–43) on high-performance liquid chromatography and Sephadex G-75 chromatography.
Noradrenaline stimulated GHRH secretion in a dose-dependent manner in the concentration range 10−10— 10−6M, with a plateau in response at 10−7M. Stimulation with noradrenaline 10−7M was blocked by idazoxan 10−5M and attenuated by thymoxamine 10−5M, but was unaffected by timolol 10−5M. Both the α2-adrenoceptor agonist guanfacine, and the α1-adrenoceptor agonist methoxamine, specifically stimulated GHRH secretion.
It is concluded that noradrenaline stimulates the release of GHRH at both α1 and α2-adrenoceptors.  相似文献   
29.
目的观察JAK2激酶抑制剂AG490对结肠癌HT-29细胞侵袭以及对基质金属蛋白酶-2(MMP-2)表达的影响,探讨STAT3信号转导通路在结肠癌侵袭转移调控中的作用。方法应用JAK2激酶抑制剂AG490处理结肠癌HT-29细胞,Matrigel肿瘤体外侵袭模型检测肿瘤细胞侵袭;Western blot检测STAT3蛋白表达;逆转录-聚合酶链反应(RT—PCR)检测MMP2mRNA表达。结果AG490可抑制JAK2/STAT3信号转导通路活化及结肠癌HT-29细胞侵袭,在此过程中AG490在mRNA水平抑制MMP-2表达。结论STAT3信号转导通路参与结肠癌细胞侵袭调控,阻断STAT3通路活化可抑制结肠癌细胞侵袭,这一作用可能是通过抑制MMP-2表达实现的。  相似文献   
30.
《灵枢·官针》是关于中医古典针法的经典文献,其中所论刺痹法,内容丰富,手法多样,至今对临床仍有重要指导意义.刺痹法共有九种,毛刺法刺皮肤治浮痹,合谷刺刺肌肉治肌痹,恢刺与关刺刺筋腱治筋痹,输刺与短刺刺骨治疗骨痹.特殊操作类又有多针、多向刺法的齐刺、傍针刺和烧针刺法的焠刺,以治疗各种经久不愈的痹痛.研究这些古刺法,对于提高痹证的治疗效果,具有一定的指导意义.  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