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   407872篇
  免费   35425篇
  国内免费   16912篇
耳鼻咽喉   3889篇
儿科学   7331篇
妇产科学   4579篇
基础医学   67780篇
口腔科学   8825篇
临床医学   31116篇
内科学   70184篇
皮肤病学   7704篇
神经病学   25354篇
特种医学   8869篇
外国民族医学   161篇
外科学   30259篇
综合类   58762篇
现状与发展   79篇
一般理论   6篇
预防医学   19306篇
眼科学   5692篇
药学   49494篇
  89篇
中国医学   15416篇
肿瘤学   45314篇
  2024年   921篇
  2023年   6548篇
  2022年   13453篇
  2021年   17180篇
  2020年   14067篇
  2019年   12998篇
  2018年   12806篇
  2017年   13125篇
  2016年   13835篇
  2015年   15866篇
  2014年   24147篇
  2013年   26595篇
  2012年   23692篇
  2011年   26834篇
  2010年   22207篇
  2009年   22051篇
  2008年   22031篇
  2007年   21306篇
  2006年   19200篇
  2005年   17055篇
  2004年   14639篇
  2003年   12789篇
  2002年   10355篇
  2001年   8753篇
  2000年   7253篇
  1999年   6502篇
  1998年   6041篇
  1997年   5476篇
  1996年   4865篇
  1995年   4346篇
  1994年   3894篇
  1993年   3291篇
  1992年   2783篇
  1991年   2557篇
  1990年   2082篇
  1989年   1856篇
  1988年   1745篇
  1987年   1440篇
  1986年   1318篇
  1985年   2035篇
  1984年   1934篇
  1983年   1404篇
  1982年   1465篇
  1981年   1163篇
  1980年   1023篇
  1979年   829篇
  1978年   590篇
  1977年   465篇
  1976年   445篇
  1975年   304篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Summary Thirty-one patients with stage IIIB or IV non-small cell lung cancer (NSCLC) were treated with intravenous 10-EdAM on a weekly basis. The starting dose was 80 mg/m2, with subsequent doses adjusted depending on evidence of toxicity. There were 20 men and 11 women with a median age of 58 years (range, 33–75). Response was evaluated in 30 patients, 5 with evaluable but not measurable tumors and 25 with measurable indicator lesions. There were no complete remissions; 3 patients achieved partial remission. Nine patients had a minor response, 6 showed no change, and 12 had progressive disease. Median survival for all 31 patients was 43 weeks (range, 12–65+). During the first 3-week period, the 10-EdAM dose was reduced or withheld in 19 patients (because of stomatitis in 12, SGPT elevation in 3, skin rash in 2, and granulocytopenia in 2), escalated in 11 patients, and unchanged in 1 patient. A mean of 34–88 mg/m2of 10-EdAM (median, 50) was given per week during the first 5-week period. Myelotoxicity was infrequent and there was no significant nephrotoxicity. Considering the modest side effects of this treatment and the conservative dose-modification schedule which mandated substantial dose reductions, we conclude that 10-EdAM is a promising antitumor agent for NSCLC.  相似文献   
992.
993.
The edema-producing activity of NNAVPLA2, an acidic phospholipase A2 (PLA2) enzyme from Naja naja atra venom (NNAV), was less potent than that of TMVPLA2 II, a basic PLA; from Trimeresurus mucrosquamatus venom (TMV). These edema-forming effects were greatly suppressed by pretreatment of rats with diphenhydramine/ methysergide or compound 48/80, which reduced the tissue content of histamine and serotonin. Heparin abolished and suppressed the paw edema caused by protamine and TMVPLA2 II, respectively, but had no effect on the NNAVPLA2-induced response. In isolated rat peritoneal mast cells, both PLA2 concentration dependently induced the release of histamine and β-glueuronidase. Again, TMVPLA2 II was more potent than NNAVPLA2. This degranulation effect of mast cells caused by TMVPLA2 II and protamine was inhibited by heparin, while that caused by NNAVPLA2 was unaffected. The edema-forming and mast cell degranulation effects were greatly decreased in both PBPB-modified NNAVPLA2 and PBPB-modified TMVPLA2 II, in which the catalytic activity of the enzymes was completely lost. PBPB-modified TMVPLA2 II-induced paw edema was also suppressed by heparin. Furthermore, this edematous response was totally reversed in rat pretreated with aspirin in combination with diphenhydramine and methysergide. These results suggest that the edema-forming effect of PLA2 is probably dependent on the presence of catalytic, positive charge and pharmacological sites on its molecule.  相似文献   
994.
重症肌无力患者胸腺肥大细胞的形态数量和超微结构研究   总被引:2,自引:1,他引:1  
为探讨研究重症肌无力(MG)患者胸腺内肥大细胞的形态数量和其超微结构变化与MG发病的关系。方法对28例MG患者作胸腺肥大细胞的形态半定量分析和光镜观察,其中16例的胸腺进行电镜检查。结果MG胸腺不仅表现组织学异常,且肥大细胞数量明显增多,尤其是在非增生胸腺内出现大量肥大细胞,而在增生的髓质和生发中心区几乎见不到。电镜观察提示肥大细胞与上皮细胞、T淋巴细胞和毛细血管关系密切,且含多种形态的分泌颗粒。结论肥大细胞对胸腺细胞的分化成熟、胸腺屏障和胸腺功能,以及MG发病均起到一定的重要作用。  相似文献   
995.
Endotoxin-induced uveitis (EIU) can be produced by systemic injection of endotoxin (ET). It is not clear yet why exclusive ocular involvement occurs in this model. To clarify this question and to establish the sequence of inflammatory events, EIU was induced in Lewis rats by footpad injection of Salmonella ET. Ocular inflammatory response (anterior chamber cells and proteins), aqueous inflammation mediators (thromboxane B2, prostaglandin E2, leukotriene B4 and substance P) and MHC class 2 (Ia) antigen expression in the ciliary body were monitored for 72 hours. Thromboxane B2 was detected early in the aqueous humor, peaking already 1 hour after ET injection. Prostaglandin E2 & leukotriene B4 peaks and a second peak of thromboxane B2 were recorded 18 hours after ET-injection, at the time of maximal ocular inflammation. MHC-class 2 expression was first detected in the ciliary body stroma at the vascular level 6 hours after ET injection and was massively expressed in the ciliary body epithelium at 18 and 72 hours. It is hypothetized that ciliary body endothelium is particularly sensitive to the effect of ET and is the site of thrombocyte adherence. Vascular damage leads in succession to cellular infiltration, release of inflammation mediators and disruption of blood-ocular barrier. MHC-class 2 expression is a secondary phenomenon and is probably at the origin of additional tissue damage from immune effector mechanisms.  相似文献   
996.
Summary Biological monitoring for carbon disulphide (CS2) exposure performed using the iodine-azide test (IAT) and 2-thiothiazolidine-4-carboxylic acid (TTCA) test in urinalysis of workers with high exposure to CS2 (112–142 mg/m3, n = 34), workers with low exposure (4–7 mg/m3, n = 16), and non-exposed university workers (n =10). Pre-shift and post-shift urine specimens were collected on three consecutive days in the exposed and for only one day in the non-exposed. According to the findings the specificity and the sensitivity seem to be low for the IAT and high for the TTCA test. Contrary to a previous report all pre-shift urine samples showed negative IATs. The TTCA test was positive in pre-shift urine even after 32 to 63.5 h without exposure, and values tended to increase during consecutive days of exposure in highly exposed workers.The possible health implications of these findings should be further investigated.  相似文献   
997.
汪南华  王锐  冷宗康  彭司勋 《药学学报》1990,25(12):920-925
缩氨基硫脲类化合物有抗肿瘤、抗病毒和抗菌等多种药理活性。Barret等首次报道了乙二醛二缩氨基硫脲(Ⅰ)的抗疟活性。Klayman等研究了缩  相似文献   
998.
999.
Background and Objective: To further understand the precise process of the tumor cell degeneration after photodynamic therapy (PDT), laser hyperthermic therapy (LH), and combined treatments using an Nd:YAG laser. It is important to examine initial morphological alteration of tumor cells after these treatments. Study Design/Materials and Methods: In this study, nude mice bearing HeLa cell tumors were treated with PDT, LH, and combined treatments of the two. Tumor tissues obtained immediately after these treatments were analyzed using electron microscopy and morphometry. Results: In the combined treatments, which produced more severe effects on tumor cells, morphological features of apoptosis such as cytoplasmic condensation, blebs, and apoptotic bodies appeared in the cells, although the typical alteration in the nuclear chromatin was not seen. Conclusion: Cytoplasmic alterations may proceed more rapidly than nuclear alterations in the cellular degeneration induced by the single or combined treatments of PDT and LH.  相似文献   
1000.
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