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   36118篇
  免费   3200篇
  国内免费   1877篇
耳鼻咽喉   580篇
儿科学   555篇
妇产科学   839篇
基础医学   4235篇
口腔科学   600篇
临床医学   4271篇
内科学   6396篇
皮肤病学   823篇
神经病学   1937篇
特种医学   1312篇
外国民族医学   17篇
外科学   3636篇
综合类   4284篇
现状与发展   4篇
一般理论   7篇
预防医学   2352篇
眼科学   796篇
药学   3683篇
  24篇
中国医学   1651篇
肿瘤学   3193篇
  2024年   83篇
  2023年   489篇
  2022年   1152篇
  2021年   1527篇
  2020年   1112篇
  2019年   1166篇
  2018年   1294篇
  2017年   1102篇
  2016年   1056篇
  2015年   1564篇
  2014年   1918篇
  2013年   1916篇
  2012年   2671篇
  2011年   2817篇
  2010年   1811篇
  2009年   1351篇
  2008年   1934篇
  2007年   1874篇
  2006年   1876篇
  2005年   1832篇
  2004年   1333篇
  2003年   1274篇
  2002年   1102篇
  2001年   903篇
  2000年   829篇
  1999年   760篇
  1998年   502篇
  1997年   464篇
  1996年   388篇
  1995年   350篇
  1994年   303篇
  1993年   227篇
  1992年   329篇
  1991年   295篇
  1990年   225篇
  1989年   185篇
  1988年   216篇
  1987年   177篇
  1986年   137篇
  1985年   131篇
  1984年   90篇
  1983年   52篇
  1982年   34篇
  1981年   43篇
  1980年   32篇
  1979年   33篇
  1978年   28篇
  1977年   27篇
  1975年   22篇
  1973年   25篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
91.
Effects of stimulation of brainstem sites on hemodynamics and plasma catecholamine levels were assessed in cats under chloralose-urethane anesthesia. Pressor areas of the dorsal medulla (DM) and ventrolateral medulla (VLM) and the depressor area of the paramedian reticular nucleus (PRN) were stimulated electrically using a monopolar electrode, or chemically using sodium glutamate microinjection. Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in caval blood above the adrenal veins. Electrical stimulation of the DM and VLM produced increases in blood pressure and in plasma NE and EPI levels that were enhanced after acute vagotomies. The NE and EPI responses were attenuated after acute, bilateral adrenalectomies, confirming augmented adrenomedullary secretion, whereas the pressor responses were intact. Injection of sodium glutamate into the same pressor regions of the DM or VLM also produced pressor responses and elevated plasma catecholamine levels, indicating that the responses resulted from activation of neuronal perikarya. Stimulation of the PRN attenuated pressor and catecholamine responses during stimulation of the DM and VLM. The results indicate that pressor responses during stimulation of the DM and VLM are due at least partly to activation of perikarya in these regions, are associated with but not dependent on adrenomedullary activation, and are enhanced after vagotomy; and that neurons of the PRN exert inhibitory modulation of the pressor and adrenomedullary responses during stimulation of VLM and DM.  相似文献   
92.
Foropenseverewoundandthewoundafterdebridement,mostscholarsthinkthewoundshouldbeclosedindelayedfirst-phase.Meshrelaxingshortincision(MRSI)methodcanclosemoreskindeficiencyandhightensionopenwound,andavoidsubcutaneoushematomaandskinflapdrift.Intheexperiment,theexperimentalmodelonrattensionskinflaphasbeeninvolved,andthecontentofendothelin(ET)inratskinflaptissuehasbeenmeasuredinvariousperiodofwoundhealingaftermeshedrelaxingshortincisionsuturewithimmunohistochemistry,inordertodiscussprobablemechani…  相似文献   
93.
目的 :探讨奶茶对大鼠体重和血清胆固醇含量的影响。方法 :将大鼠随机分为对照、脂对照、奶、茶和奶茶五组 ;高脂饲养的同时分别用水、奶、茶和奶茶进行灌胃 ,定期测定大鼠的血清胆固醇 (TC)。结果 :实验期间奶茶组大鼠体重的增长量高于其他三个高脂饲料组 ,且明显高于对照组 (P <0 .0 5 ) ;高脂饲料组大鼠的血清胆固醇含量明显增加 ,但增长量在高脂饲料组间差异无显著性 (P >0 .0 5 )。结论 :本实验浓度的奶茶对高脂饲料诱导的大鼠血清胆固醇升高未见有降低作用  相似文献   
94.
The case of a patient in whom acute pericarditis was the initial manifestation of an idiopathic hypereosinophilia is reported. Endomyocardial abnormalities were not found by echocardiography. Response to prednisone therapy was good; symptoms, pericardial effusion and eosinophilia early disappeared after therapy. Some clinical aspects of this uncommon disease are discussed.  相似文献   
95.
糖尿病酮症酸中毒诱因调查及防治对策   总被引:3,自引:0,他引:3  
目的 :探讨糖尿病酮症酸中毒 (DKA)诱发因素的防治对策 ;方法 :采用计数方法间接确定住院的 57例DKA各种诱因的发生率 ,两组间进行对比分析 ,找寻诱因产生的根源 ;结果 :感染为诱因者 3 5例 ( 61 .4% ) ,用药不当 8例 ( 1 4 .0 % ) ,医源性因素 6例 ( 1 0 .5% ) ;感染诱因中呼吸道感染 2 3例 ( 65.7% ) ;病程一年以上者感染诱发率高于病程一年以下者 (P <0 .0 5) ,医源性诱因 1 0 0 %发生在病程一年以下且无糖尿病病史的 2型糖尿病 ;结论 :感染是DKA的首要诱发因素 ,严格控制血糖是减少感染发生率的必要手段 ,要避免用药不当这个主要诱因有赖于加强卫生宣教 ,取得患者在治疗上的配合 ;糖尿病的早期诊断可防止医源性诱因的发生  相似文献   
96.
The identity and relative contributions of various sources of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) to recently deposited sediments collected in Newark Bay and its major tributaries were determined using polytopic vector analysis (PVA), a multivariate statistical technique relatively new in the chemometric literature. The concentrations of 2,3,7,8-substituted PCDD/Fs were assayed in eighty-one surface and near-surface sediment samples collected from the Passaic River, Hackensack River, Arthur Kill, Elizabeth River, Kill Van Kull, Port Elizabeth, and Port Newark navigation channels and Robins Reef, which is located in New York Harbor. PVA modeling revealed five predominant 2,3,7,8-substituted PCDD/F fingerprint patterns in geographically plausible distributions throughout the estuary. This was consistent with the current understanding of hydrodynamic and sedimentation conditions reported in the literature for Newark Bay. Three patterns contained 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), which is alleged to originate from a single industrial source on the lower Passaic River. One of the fingerprints containing 2,3,7,8-TCDD was present in moderate proportions (10–20%) in surface sediments near the site, but was generally observed in low abundance (<5%) elsewhere in the estuary. A fingerprint pattern characteristic of PCDD/F profiles in effluents from municipal sewage and waste water treatment plants was widely distributed in the estuary, but reached its highest relative proportions in the Elizabeth River. A third fingerprint pattern was highest in the Arthur Kill and lower Passaic River and closely matched the residue patterns found in several types of combustion sources. A fourth finger-print pattern in Hackensack River and lower Passaic River sediment matched the PCDD/F profile reported in PCB Aroclor® formulations. A fifth fingerprint pattern matched the profile in recycled pulp and paper mill effluents and was highest in Kill van Kull and upper Passaic River sediment. The majority of PCDD/Fs in sediment from Reaches B, C, and D of Port Newark and Port Elizabeth were attributable to sediments transported via the Arthur Kill and the Kill Van Kull. These results are consistent with those previously reported using principal components analysis, which indicated that 2,3,7,8-substituted PCDD/F patterns in the sediments of Newark Bay are consistent with discharges from multiple sources.  相似文献   
97.
Ten cases of pediatric fulminant hemophagocytic syndrome, encountered between 1986 and 1989, are described. They occurred in the summer, and the patients presented with fever, jaundice, hepatosplenomegaly, pancytopenia, coagulopathy, and abnormal liver function. Bone marrow studies revealed infiltration by atypical T-lymphoid cells, rare B immunoblasts, and mature histiocytes with hemophagocytosis. Initially, histiocytic medullary reticulosis was suspected in six cases. The clinical course was characterized by rapid deterioration, with a mean period of 16 days from onset of fever to death. The main causes of death were coagulopathy with multiple organ failure and opportunistic infection. In seven of eight cases studied by serologic assay and Southern blot hybridization, acute or active Epstein-Barr virus (EBV) infection was documented. It is suggested that an atypical or fulminant form of primary EBV infection distinct from classic infectious mononucleosis was prevalent in previously healthy children in Taiwan. Younger age involvement and seasonal clustering were characteristic of the disorder described.  相似文献   
98.
人体中氧氟沙星的立体选择性代谢   总被引:2,自引:1,他引:1  
5名健康志愿者日服单剂300mg氧氟沙星[(±)-Of1]后,采用立体选择性的RP-HPLC手性流动相添加剂法测定尿中S-(-)-Of1和R-(+)-Of1浓度结果显示Of1在人体内呈现立体选择性代谢。尿中排泄的S-(-)-Of1/R-(+)-Of1之比随时间变化。服药后2hS/R是0.875,24h增加到1.150.S-(-)-Of1的消除半衰期(t1/2)是4.57h;消除速率常数(k)是0.154h;药时曲线下的面积(AUC)为1.17mg·h-1.mL-1;R-(+)-Of1的t1/2为4.18h,k为0.168h-1,AUC是1.78mg·h-1·mL-1;经配对t检验这三对参数间有显著性差异,P值分别小于0.01,0.001和0.005.因此两对映体在人体内呈现立体选择性处置  相似文献   
99.
荧光定量聚合酶链反应检测乙肝病毒及其临床意义   总被引:3,自引:0,他引:3  
OBJECTIVE: To study the relationship between the serum contents of HBV DNA copies and the HBV serum index of immunology and the degree of hepatocyte injury in patients with HBV hepatitis. METHODS: The contents of HBV DNA copies were detected by fluorescence quantitative PCR (FQ-PCR), and the HBV serum index of immunology by ELISA. RESULTS: The contents of HBV DNA copies had a significant difference between HBeAg (+)/anti-HBe (-) group (42 patients) and HBeAg (-)/anti-HBe (+) group (57 patients) or HBeAg (-)/anti-HBe (-) group(11 patients) (P < 0.05), while there was no significant difference between HBeAg (-)/anti-HBe (+) group and HBeAg (-)/anti-HBe (-) group(P > 0.05). The contents of HBV DNA copies had no correlation with the severe degree of hepatocyte injury(P > 0.05). CONCLUSION: Anti-HBe is not the terminal sign of HBV replication. The severe degree of hepatocyte injury has not a direct correlation with the contents of HBV DNA copies.  相似文献   
100.
经阴道超声诊断子宫内膜癌   总被引:1,自引:0,他引:1  
目的 探讨应用经阴道超声(TVS)诊断绝经前后出血妇女子宫内膜癌的价值。方法 采用彩色多普勒超声诊断仪检测74例阴道异常出血的妇女,其中绝经前28例,绝经后46例,所有患者均取子宫内膜组织行病理对照。结果 TVS检测子宫内膜癌的敏感性、特异性、假阳性率、假阴性率、阳性预测值和阴性预测值,绝经前妇女依次为61.5%,50.0%,14.3%,23.8%,94.1%和54.5%,绝经后妇女依次为97.3%,55.6%,44.4%,2.7%,90.0%和83.0%。结论 TVS检测可作为子宫内膜癌首选的筛查方法,尤其对于绝经后妇女价值更大。  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