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   116423篇
  免费   6067篇
  国内免费   138篇
耳鼻咽喉   1771篇
儿科学   5249篇
妇产科学   3943篇
基础医学   16113篇
口腔科学   2843篇
临床医学   8360篇
内科学   22041篇
皮肤病学   3363篇
神经病学   9015篇
特种医学   5070篇
外国民族医学   32篇
外科学   19141篇
综合类   1600篇
一般理论   29篇
预防医学   5870篇
眼科学   3396篇
药学   8082篇
中国医学   325篇
肿瘤学   6385篇
  2018年   895篇
  2017年   781篇
  2016年   1095篇
  2015年   1228篇
  2014年   1619篇
  2013年   2376篇
  2012年   3128篇
  2011年   3179篇
  2010年   1987篇
  2009年   1941篇
  2008年   3267篇
  2007年   3503篇
  2006年   3652篇
  2005年   3758篇
  2004年   3706篇
  2003年   3572篇
  2002年   3521篇
  2001年   7027篇
  2000年   6970篇
  1999年   5866篇
  1998年   1629篇
  1997年   1562篇
  1996年   1340篇
  1995年   1208篇
  1994年   1092篇
  1993年   1119篇
  1992年   3770篇
  1991年   3579篇
  1990年   3566篇
  1989年   3354篇
  1988年   2995篇
  1987年   2901篇
  1986年   2809篇
  1985年   2622篇
  1984年   1950篇
  1983年   1600篇
  1982年   932篇
  1981年   922篇
  1980年   766篇
  1979年   1830篇
  1978年   1353篇
  1977年   1117篇
  1976年   939篇
  1975年   1189篇
  1974年   1218篇
  1973年   1203篇
  1972年   1044篇
  1971年   982篇
  1970年   885篇
  1969年   788篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
A mutant form of ammodytoxin A, a neurotoxic phospholipase A2 from the venom of the long nosed viper Vipera ammodytes ammodytes, was prepared by site-directed mutagenesis, conjugated to a nanogold particle and inoculated into the antero-lateral aspect of one hind limb of female mice. Eight hours later the mice were killed, the soleus muscles of both ipsi- and contra-lateral hind limbs were removed, exposed to a silver enhancing medium and then prepared for transmission electron microscopy. Silver-enhanced particles were subsequently found concentrated in the peri-synaptic area, particularly within the synaptic gutter and the deep synaptic folds, and in many cases had been taken up into the cytoplasm of the terminal boutons of the motor axon. The results suggest that the presynaptic neurotoxicity of snake venom phospholipases A2 involves several components of the neuromuscular apparatus, including intracellular organelles of the motor nerve terminal.  相似文献   
95.
A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment.  相似文献   
96.
K Rehse  U Lükens  G Claus 《Archiv der Pharmazie》1987,320(12):1233-1238
Platelet Aggregation Inhibiting and Anticoagulant Effects of Oligoamines, VII: Benzene-1,3,5-trialkanamines Seventeen title compounds were synthesized. Platelet aggregation induced by collagen in vitro is inhibited by 9 of them at IC50 = 2–4 μmol/L. Seven compounds depress the formation of fibrin to ≦ 25 % of normal in concentrations below 50 μmol/L. Compound 15 [4-(2-thienylbutyl)benzene-1,3,5-trimethanamine is the first oligoamine which shows anticoagulant and antiplatelet effects at the same concentration (25 μmol/L).  相似文献   
97.
Phenytoin-induced gingival overgrowth is a recognized side effect in many cerebral palsy patients using diphenyl hydantoin for the control of seizures. Severe gingival overgrowth in these patients can affect normal masticatory function, lead to poor occlusal development, and compromise esthetics. This report addresses the complex nature of treating phenytoin-induced gingival overgrowth in a mentally retarded 20-year-old female patient. For this patient, full-mouth gingivectomy procedure was performed under general anesthesia in a single session. Post operative follow-up was uneventful. This article discusses major indications, contraindications, and protocols to be followed for periodontal surgical procedures done under general anesthesia.  相似文献   
98.
99.
The study presented here was conducted to evaluate the performance of the newly available RIDASCREEN Set (R-Biopharm AG, Darmstadt, Germany) for the detection of immunoglobulin G antibodies against Entamoeba histolytica. The sensitivity and specificity of this new enzyme-linked immunosorbent assay were evaluated using a panel of sera from 239 individuals. The assay was positive for 43 of 44 patients with invasive amebiasis, including all 18 patients with amebic liver abscess, while it was negative for 190 of 195 adult controls who were either healthy individuals or patients with other parasitic diseases. The kit was found to be highly specific (97.4%) and sensitive (97.7%) for detecting antibodies against E. histolytica in humans. Although antibody titers in patients with amebic liver abscess tend to be higher on average than in patients with invasive amebiasis, it is not possible to distinguish the two forms solely based on the results of this commercial test.  相似文献   
100.
The detection of antineuronal antibodies against cytoplasm and nuclei of Purkinje cells is considered to be an essential factor in the diagnosis of neurologic paraneoplastic syndromes. Published data rely on different immunological methods and relatively small numbers of patients. The clinical relevance of this phenomenon is not clear from the literature. A positive correlation between antibody detection and the appearance of neurologic paraneoplastic syndromes has been reported, but this finding has been questioned in critical reviews.  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