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   33157篇
  免费   3713篇
  国内免费   998篇
耳鼻咽喉   399篇
儿科学   387篇
妇产科学   398篇
基础医学   1993篇
口腔科学   9712篇
临床医学   2308篇
内科学   2484篇
皮肤病学   613篇
神经病学   698篇
特种医学   442篇
外国民族医学   1篇
外科学   1835篇
综合类   3857篇
现状与发展   4篇
预防医学   1548篇
眼科学   309篇
药学   6401篇
  34篇
中国医学   2820篇
肿瘤学   1625篇
  2024年   71篇
  2023年   626篇
  2022年   670篇
  2021年   1292篇
  2020年   1437篇
  2019年   1405篇
  2018年   1348篇
  2017年   1299篇
  2016年   1359篇
  2015年   1324篇
  2014年   2030篇
  2013年   2536篇
  2012年   1932篇
  2011年   2026篇
  2010年   1596篇
  2009年   1435篇
  2008年   1397篇
  2007年   1461篇
  2006年   1357篇
  2005年   1308篇
  2004年   1126篇
  2003年   1040篇
  2002年   894篇
  2001年   811篇
  2000年   666篇
  1999年   577篇
  1998年   489篇
  1997年   499篇
  1996年   411篇
  1995年   384篇
  1994年   343篇
  1993年   252篇
  1992年   291篇
  1991年   215篇
  1990年   203篇
  1989年   211篇
  1988年   177篇
  1987年   157篇
  1986年   128篇
  1985年   158篇
  1984年   149篇
  1983年   107篇
  1982年   126篇
  1981年   116篇
  1980年   85篇
  1979年   67篇
  1978年   55篇
  1977年   67篇
  1976年   45篇
  1975年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
我军第二次部队人员牙周疾病捷径调查和分析   总被引:2,自引:0,他引:2  
目的:了解牙周疾病在我军部队人员中的流行情况。方法:采用世界卫生组织1997年版口腔健康调查基本方法和标准器材。结果:共调查1 269人,结果表明,我军现役人员男性牙龈炎患病率为21.12%,牙结石检出率为44.05%,早期牙周病患病率为2.75%,晚期牙周病患病率为0.39%。结论:根据本次调查结果和我军第一次口腔健康的牙周疾病监测,以及外军相关资料比照进行牙周疾病流行病学研究分析表明,我军牙周疾病患病率比较平稳,牙周疾病大部分处于早期阶段。  相似文献   
62.
BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue.  相似文献   
63.
The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.  相似文献   
64.
目的探讨目前老年护理医院院内感染病原菌及其耐药特征。方法对2000年4月-2004年3月徐汇区两家老年护理院出院病人的病史进行统计分析。结果两家老年护理院共计发生医院感染939例次,医院感染率12.86%,检出病原菌284株,阳性率30.28%;病原菌以革兰阴性菌为主,占44.65%,其次为真菌、革兰阳性菌,分别为29.12%、25.92%,位于前3位的病原菌分别为其他真菌(14.36%)、白色念珠菌(12.23%)、铜绿假单胞菌(8.69%);除嗜麦芽寡养单胞菌外,革兰阴性菌以亚胺培南最敏感,敏感率87%,对氨苄西林、阿莫西林的耐药率〉51%,对头孢哌酮、哌拉西林的耐药率〉33%;MRSA和MRSE的检出率高达86.76%和76.32%;混合感染率34.51%。结论老年护理院医院感染率高.真菌所占的比例高;细菌对抗菌药物的耐药性相当严重。  相似文献   
65.
介绍大型尿基复合肥装置在生产中引起产品养分偏差的原因及采取的操作措施。  相似文献   
66.
It has been reported that poor glycaemic control predisposes to oral candidal infection in diabetic patients. For instance, the carriage of Candida species and the density of candidal growth in the oral cavity is frequently claimed to be increased in patients with diabetes mellitus. However, the validity of these observations remains controversial. Hence, we review and discuss here the clinical data in the literature on the relationship between diabetes and oral candidal carriage and infection, and possible mechanisms associated with its pathogenicity.  相似文献   
67.
目的探讨超声引导下活体犬肝注射不同剂量的醋酸高渗氯化钠液(acetic acid hypertonic saline solution,AHS)后行射频消融(RFA),观察犬肝一次性毁损体积的变化。方法使用LDRF-120S多极RFA系统联合AHS对活体犬肝行RFA。健康成年杂种犬30只,随机分为5组(n=6)。A组:注射2ml AHS后立即行RFA;B组:注射2ml AHS后延时5min行RFA;C组:注射4ml AHS后立即行RFA;D组:注射4ml AHS后延时5min行RFA;E组:注射6ml AHS后立即行RFA。结果5组间平均起始阻抗差异无统计学意义(P>0.05);5组间平均消融时间差异有统计学意义(F=83.831,P<0.001),LSD-t检验分析各组间两两比较差异有统计学意义(P<0.001),在观察范围内E组平均消融时间最长;5组间平均毁损直径差异有统计学意义(F=53.488,P<0.001),在观察范围内E组平均毁损直径最大,LSD-t检验分析除D与E组间差异无统计学意义(P>0.05)外,其余各组间两两比较差异有统计学意义(P<0.001);网状纤维染色显示凝固坏死区及其邻近的正常肝组织均可见血管内血栓形成;E组在AHS注射过程中出现不同程度的外溢;A、B、C及D组14d内无动物死亡,E组死亡4只。结论活体犬肝局部注射AHS4ml后延时5min行RFA即可达到较理想的毁损体积。  相似文献   
68.
BACKGROUND: Steroid dependency is a major problem seen after therapy for idiopathic nephrotic syndrome in childhood. Although there is consensus about the usage of cyclophosphamide (CYC) in frequent relapsers, there is still a controversy concerning its usage in steroid-dependent nephrotic syndrome (SDNS). METHODS: In the present study, nineteen children with SDNS were treated with CYC: ten via the intravenous (i.v.) route, and nine via the oral route. Remission was then maintained with prednisolone. Oral CYC therapy consisted of CYC at a dose of 2 mg/kg per day for 12 weeks. Intravenous (i.v.) CYC therapy consisted of CYC 500 mg/m2 per month (with intravenous 3500 cc/m2 per 24 h one-third saline hydration) for 6 months. RESULTS: The cumulative dose of CYC was 168 mg/kg in the oral group and 132 mg/kg in the IV group. Daily oral CYC dose was 1.96~0.31 mg/kg, whereas i.v. CYC dose was 0.73~0.03 mg/kg. Long-term complications and side-effects such as alopecia, infection and hemorrhagic cystitis were not observed in the i.v. CYC treated group. In the long term, the dosage of prednisolone that held remission after CYC, the annualized relapse rates and the subsequent relapse time were significantly better in the i.v. CYC group, and the number of patients in remission for 2 years was significantly higher in the i.v. treated group (P<0.05). CONCLUSIONS: In SDNS, i.v. CYC has a long lasting effect with lower annualized relapse rates and longer subsequent relapse time with a lower steroid dosage required to maintain remission than oral CYC. The results of the present study showed the safety of the i.v. route, and it is the preferable treatment in noncompliant patients for its long lasting remission and simple and inexpensive follow up.  相似文献   
69.
目的 探讨实验性内听动脉阻断与术后听力改变的关系及术中听觉监控的方法。方法 实验兔乙状窦后进路暴露小脑桥脑角,下压小脑暴露内听道及第Ⅷ神经复合体,分辨出内听动脉,予阻断不同时间,分别行蜗神经直接复合动作电位(DCAP)和畸变产物耳声发射记录(DPOAE)。结果对照组DCAPN1波潜伏期值无明显改变。内耳血供阻断10s和30s组在压迫开始后3min,DCAPN1波潜伏期值均恢复为初始值。内耳血供阻断1min组在压迫开始后3h,DCAPN1波潜伏期值未恢复为初始值假手术组DPOAE幅值无明显改变,内耳血供阻断10s、30s对DPOAE幅值无影响,内耳血供阻断1min使得DPOAE幅值下降结论兔内耳血供阻断1min可能造成兔听觉不可逆损伤。DCAP、DPOAE能有效、持续地监控内耳血供阻断,是耳神经外科手术中实用的听觉监测手段。  相似文献   
70.
市售三厂家18种复方氨基酸注射液的质量评价   总被引:3,自引:0,他引:3  
目的对市售3厂家(A、B和E)共9批18种复方氨基酸注射液进行质量比较。方法参考国内外同类产品质量标准,从澄明度、透光率、性状、pH值、不溶性微粒、抗氧剂量、细菌内毒素和含量等方面进行比较。结果外观均为无色澄明液体,430nm波长处透光率均大于99%,pH在5.42~6.61间;A、B、E3厂不溶性微粒≥10、≥25μm的粒子数分别为1.41、0.32,0.83、0.21和1.55、0.56个/ml;抗氧剂的量分别为<33、近330和>500mg/L;细菌内毒素检查与含量测定符合中国药典及国家标准要求。结论不同厂家的产品质量确实存在一定的差异。  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